DEPARTMENT OF THEINTERIOE REPORT OF THE CHIEF ASTRONOMER, 1909 'PENDIX No. 2 DOS STROPHYSICAL WORK BV J. S. PLASKETT. B.A. OTTAWA GOVERNMENT PRINTING BUREAU 1911 9-10 EDWARD VII. SESSIONAL PAPER No. 25a A. 1910 27 1911 CALIFORNIA. APPENDIX 2. REPORT OF THE CHIEF ASTRONOMER, 1909. ASTRO PHYSICAL WORK J. S. PLASKETT, B.A. 143 9-10 EDWARD VII. SESSIONAL PAPER No. 25a A. 1910 CONTENTS. PAGE. Introduction 147 Papers published during the year 150 The Spectrographs 151 The DQSjgn. of Spectrographs for Kadial Velocity Determinations 152 The'Opfrcal Parts.'/ ;. \ \ 153 Mechanical Design. .' .*. 161 The .Nelv'^injgie-PMStn 3p/5e.trograph 163 Tfie Optical 'Parts."/ :."'.' IG3T The Guiding Telescope , 164 The Comparison Apparatus. . 164 Slit and Slit Diaphragms 164 The Mechanical Parts. 165 The Spectrograph Box 165 The Supporting Cradle 166 Temperature Control '. ^ 167 Adjustment of the Instrument 168 The new Spectrograph in practice 169 Camera Objectives for Spectrographs 170 Measurement and Reduction of Stellar Spectra 175 The Spectro-Comparator 177 Measures of ft Geminorum 183 The Ccelostat Telescope 207 Radial Velocities 209 Binaries under Observation 210 New Spectroscopic Binaries. . 210 8 Aquihe 212 The Orbit of Orionis 214 Lines in /? Orionis 215 Summary of Measures 216 Summary of Mean Velocities per night 221 Appendix A, W. E. Harper. The Orbit of 6 Aquilae 225 Measures of Aquilse 226 Summary of Corrections 231 Final Elements. 232 Previous Observations 233 Additional Note on Allegheny Determination 235 The System of e Herculis 236 Early Observations of c Herculis 238 Ottawa Measures of c Herculis 239 Normal Places 240 The Spectroscopic Binary ^ Bob'tis 241 Previous Observations 241 Ottawa Observations 242 Elements of Orbit 244 144 REPORT OF THE CHIEF ASTRONOMER 145 SESSIONAL PAPER No. 25a Appendix B. J. B. Cannon. PAGE. The Spectroscopic Binary a Coronas Borealis. . . 245 Lines Measured 245 Measures of a Coronaee Borealis . . . 246 Elements 249 Appendix C. R. E. DeLury. The twenty-three foot Solar Spectrograph 251 Optical Parts 251 Mountings 251 Slit Attachment 252 Camera and Plate Holders 253 Guide Plate for the Sun's Image 253 Some Results 254 Appendix D. R. M. Motherwell. Double Star Measures 257 Comet 1908 c (Morehouse) 258 Occupations of Stars by the Moon 259 Instruments used on Boundary and Geodetic Surveys 260 Aberration of the Stellar Camera Objective 260 Tests for Spherical Aberration 261 Testing for Chromatic Aberration 266 Changing the Distance between the Components of the Outer Combination 267 Tables 268 Appendix E. Measures. Orionis Record of Spectrograms 278 Measures ,. 286 Aquilse Record of Spectrograms 378 Measures 380 t Herculis Record of Spectrograms 406 Measures ; 409 Boo'tis Record of Spectrograms , 454 Measures 455 Corona? Borealis Record of Spectrograms 482 Measures 484 8 Aquilse Record of Spectrograms 535 Measures.. ., 536 738385 25a 123 9-10 EDWARD VII. SESSIONAL PAPER No. 25a A. 1910 ILLUSTRATIONS. PAGE. 1. Diagram of Refraction through Prism 153 2. New Single-Prism Spectrograph 164 3. New Single-Prism Spectrograph 164 4. Spectrograph Box 166 5. New Single-Prism Spectrograph, ready for use 168 6. Long-Focus Objectives with three prisms 174 7. Short-Focus Objectives with three prisms 174 8. Objectives tested with one prism 174 9. Spectro-Comparator 178 10. Diagram of Spectro-Comparator 178 11. Diagram of Spectro-Comparator 178 12. Form of Silvering on prism 178 13. Coelostat House 208 14. Coelostat Telescope Mechanism, looking north 208 15. Ccelostat Telescope Mechanism, looking south 208 16. Velocity Curve of ft Orionis 222 17. Final Velocity Curve of Aquilse 232 18. M. Deslandre's Observations 234 19. Deslandres' 1902 Observations 234 20. Allegheny Observations. Ottawa Curve 234 21. Velocity Curve of e Herculis 238 22. Velocity Curve of rj Bootis ." 244 23. a Coronse Borealis, Curve from Hydrogen lines and Calcium line 250 24. Velocity Curve of a Coronse Borealis 250 25. Solar Spectrograph 252 26. Rear end of Solar Spectrograph 252 27. Slit Mechanism of Solar Spectrograph 252 28. Front end of Solar Spectrograph 252 29. Focal Curves of Solar Spectrograph 254 30. Reproductions of Solar Spectra 254 31. Morehouse's Comet 258 32. Morehouse's Comet 258 33. Morehouse's Comet 258 34. Morehouse's Comet 258 35. Morehouse's Comet 2i58 36. Morehouse's Comet 258 37. Stellar Camera 260 38. Determination of Focus 261 39. Zonal Disc 262 40. Zonal Differences of Focus ; 264 41. Zonal Differences of Focus 264 42. Zonal Differences of Focus 264 43. Curvature of Field at different Zones 264 44. Curvature of Field at different Zones 264 45. Chromatic Aberration Curve 267 46. Zonal Differences of Focus 268 47. Star Photographs at different Separations 268 146 REPORT OF THE CHIEF ASTRONOMER 147 SESSIONAL PAPER No. 25a APPENDIX 2. ASTKOPHYSICAL WOEK BY J. S. PLASKETT, B.A. OTTAWA, March 31. 1909. W. F. KING, C.M.G., LL.D., Chief Astronomer, Department of the Interior, Ottawa. SIR, I have the honour to submit the following report upon the work carried on in the Astrophysical Department and in the other departments of the work ot % the Observatory under my direction during the past year. It gives me pleasure to report satisfactory progress in all lines and to state that the work accomplished both in quality and quantity shows gratifying improvement over the records of previous years. As in previous years also it has been found necessary to spend considerable time in preparatory work, in testing, adjusting, and perfecting the instruments and appliances used, and in experimenting to determine the best methods of procedure. Although the time spent 011 such work necessarily diminishes the quantity of routine work accomplished, it is in my opinion time well spent, if through such investigations and experiments we are in a position to do a larger quantity of more accurate work. Consequently, much of my time during the past year has been devoted to investigations bearing on improvements in instruments and methods, of which full details will be given later. It gives me much pleasure to be able to speak in the highest terms of the very satisfactory work done by my assistants, Messrs. Harper, Motherwell, DeLury. Cannon and Parker. As heretofore, the principal work has been the determination of the radial velo- cities of stars by means of the spectroscope, and in this work observations have been chiefly confined to known spectroscopic binaries for the determination of the elements of their orbits. However, observations on some stars with early type spectra have also been secured during times when sufficient binaries have not been available, and in measuring up the plates we have found the velocities of four of these stars to be vari- able; 8 Herculis, y Aquarii, i Andromeda?, Persei. The two latter, it has since been learned, had been previousy found variable at the Yerkes Observatory, but not pub- lished, so that our discovery was independent. The elements of the orbits of five spectroscopic binaries have been obtained, least squares corrections being applied in every case. The stars are 6 Aquilae, a Coronas Borealis, 77 Bob'tis, c Herculis, ft Orionis. These stars will be discussed in detail below, but it may be of'interest to mention that only in one case, rj Bootis, have the observa- tions been entirely satisfied by velocity curves due to simple elliptic orbits. In 6 Aquilse and e Herculis a secondary disturbance due possibly to a third body, has been present. In a Corona? Borealis the elements deduced from the hydrogen lines and the calcium, K t line differ from those obtained from the magnesium A4481-4, while in ft Orionis the amplitude of the velocity seems to be variable. This latter is of especial interest on account of the measures made at Yerkes and Lick Observatories showing- its velocity to be constant within the apparent errors of observation. 148 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 Besides the binaries above, whose orbits have been determined, there are twelve others under observation, on three or four of which the work is well advanced. On the remainder, however, a considerable number of observations are still required. About 90 per eent of the binaries observed here are stars of early type, in the major- ity "of which tie lines in the spectra are broad and diffuse, in some cases unsymme- trioeflly so, and consequently difficult of measurement. In such cases the agreement aiao-hg the Irndsin a plate is poor and the error of measurement is high, the probable errors of single plates being as great as 7km. per second in some cases. It is evident that, unless there is a large range of velocity, the elements of the orbits of such stars are subject to considerable uncertainty, and indeed in several cases the star has had to be abandoned pn this account after considerable work had been done on it. The instrumental equipment for. this work has been increased since my last report by the addition of a new single-prism spectrograph designed by myself, and con- structed, except the optical parts, entirely in our own workshop. Owing to press of repair and other work it was not completed and put into commission until about the first of March, but it has fulfilled all expectations both as regards shortening of ex- posure time and in respect to its stability and freedom from flexure. The displace- ment of the spectrum lines produced by a revolution of 180, this producing the maxi- mum amount of flexure, is quite unmeasurable and is not- even certainly visible under high power magnification; there is no question but that it is the most stable single- prism spectograph ever constructed. The difference between it and the previous instrument, which was for its type a rigid example, is very marked, the displacement in the early instrument being equivalent to a velocity of over 100km. per second. My investigation on the fields given by different types of camera objectives for spectrographs was completed, and a concise account of the performance of all the ob- jectives " tested will be given below and will also appear in the Astrophysical Journal in May. Since my previous report a new single material Brashear objective for the new single prism spectrograph has been received and tested. Its angular aperture is about 50 per cent greater than the original one and when received, owing to tho greater difficulty in correction, it had a small amount of positive aberration. By the kindness and through the skill of Mr. McDowell this aberration was finally removed and the objective is now practically perfect for its purpose. A special short focus objective by Ross has also been received and tested, giving beautiful definition and a fairly flat field. Thus, the requirements for all types of camera objectives have been successfully met, and there are now available suitable objectives for all classes of radial velocity and other spectroscopic work. The investigation on the effect of increasing the slit width on the errors of mea- surement in radial velocity work has been continued with the two different dispersions now available. The new single-prism spectrograph and a short focus objective with the three prism instrument have been tested, giving results that bear out and extend those previously obtained. It is shown that, so far as early type spectra are concerned, both accidental and systematic errors approach a minimum value for a slit 0- 051mm. wide and that the use of a narrower slit, instead of increasing the accuracy as has generally been supposed, has to a certain degree the opposite effect, to say nothing of the proportional increase of exposure required. A detailed report of this work will be postponed to allow it to be finally completed. In presenting the work on radial velocities and allied investigations in detail, I have adopted the same plan as last year, of having each observer give the details and results of the work he has been engaged on. Consequently, below will be found, besides my own remarks on radial velocities in general, my description of the new spectrograph, the investigations on camera objectives and on the effect of slit width, and the orbit of ft Orionis, the orbits of Q Aquilse, 77 Bob'tis and c Herculis by Mr. Harper, and the orbit of a Corona? Borealis by Mr. Cannon. Mr. Parker, the third observer in radial velocity work, besides measuring many miscellaneous plates, spent REPORT OF THE CHIEF ASTRONOMER 149 SESSIONAL PAPER No. 25a a great deal of time on the binary T Tauri, but owing to difficulties due to causes out- lined above was unable to obtain a satisfactory orbit and further observations next season will probably be necessary. Work with the coelostat telescope in spectroscopic investigations of the sun has made satisfactory progress, although not as much has been accomplished as we had hoped. This has been due to various unavoidable constructional delays in having the 23-foot spectrograph and its attachments completed, to a long delay while the solar research laboratory was torn up for the installation of underground pipes and an elec- tric pump for draining the transit house piers, and to a very thorough investigation of some peculiar properties in the plane grating used as the dispersion piece in the spectrograph. This investigation, which is fully described by Dr. DeLury below, showed that only by masking part of the grating could even fair definition be secured, while the best definition is necessary for accurate results in the determination of the solar rotation. A number of plates for this purpose have been secured and some pre- liminary measures by Dr. DeLury will be given. An illustrated description of the coelostat telescope and mechanism will be given by myself, and a description of the spectrograph and attachments by Dr. DeLury. Mr. Motherwell has used the equatorial on three half nights per week in micro- metric measures of double stars and has obtained a number of good measures, although his, as well as all other work with the telescope, has been much handicapped by the exceptionally poor observing weather of last fall and early winter. For nearly four months, smoke and cloud prevented almost all observations. This was especially unfor- tunate on account of the presence of Morehouse's comet, an especially interesting ob- ject, photographically, which this bad weather prevented from being photographed here more than half a dozen times. However, Mr. Motherwell will give an account in Appendix D of the double star measures obtained, of the occultations of stars by the moon observed, and of the photographs of the comet secured. A full account of an interesting and useful investigation by Mr. Motherwell on the aberration of the 8" Brashear Photographic Doublet, used in making the comet pictures, will be given. When this instrument was first tested by me, soon after the Observatory was completed, it was found to give halos around the stars of medium intensity, while in the brighter stars this halo had become so fully exposed as to make images of uniform intensity and of large diameter. This difficulty I ascribed to spherical aberration, but this diagnosis was opposed by the makers of the lens. I suggested to Mr. Motherwell as a suitable and useful subject for investigation to determine by Hartmann's method of extra-focal exposures the amount of spherical aberration present. His thorough tests showed the lens to have negative aberration to the extent of about 3 -5mm., which in our opinion was quite sufficient to account for the halo observed. A suggestion of Mr. McDowell that it was due to chromatic aber- ration was found by Mr. Motherwell not to be the case. The matter remained in abey- ance for some time, when on a further suggestion from Prof. Hastings the separation of the elements of the front component was changed to remove the halo, supposedly a ' ghost ' due to internal reflections. However, a test showed no improvement on the original positions in the slight change proposed. Further correspondence with Mr. McDowell resulted in a suggestion from him to increase the separation by about 2mm., which would practically remove the aberration. On this being done and the distance adjusted so that, the aberration was removed, the halo disappeared which was a strik- ing confirmation of our contention that it was caused by aberration. A recent letter from Mr. McDowell admits that we were right as he had proved by refiguririg a lens giving a similar halo. In consequence, the objective will be sent to Alleghney to have this aberration removed and with its already very flat field we should have an unequalled star camera. In this regard, I would urge upon you the desirability of supplying the camera with a separate mounting. Its attachment to the equatorial telescope results in seriously 150 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 limiting its usefulness; for when star photographs are being made, no work, other than the guiding, can be done with the equatorial. A separate mounting, however, would enable the two to be used independently and much more use could be made of the camera than is possible at present. The quantity of repair and other work has increased so greatly, that the two mechanicians, Mr. Mackey and Mr. Lucas, the latter having been appointed since nay last report, have not been able to keep up with all the work required. Repairs and minor alterations in the field instruments used in the Geodetic and Boundary Surveys, occupy about one-half their time, leaving the remainder for new work. The new single-prism spectrograph, the mechanical parts of the solar 23-foot focus spectro- graph, and new hardened steel pivots on the meridian circle are the principal pieces of work accomplished. Besides these are numerous smaller pieces of work. Scarcely a day passes that some work does not come in. The equipment of the machine shop has been increased by a 14 inch by 7 foot Hendry Norton lathe, which is installed and in use. With two lathes there is now no possibility of delaying work for lack of tools. The lathe is the tool most used in machine work and frequently cases occurred where both men required the lathe at the same time; in consequence the work could not be done to the best advantage. The workshop is too small for the tools and the amount of work done, and moreover the light in it is not of the best. It is desirable that, as soon as possible, provision be made for a suitable workshop above ground with ample room and light. The necessity and economy of a suitably equipped workshop for the Observatory are so evident, and the probability of an increase in its capacity being required is so great, as to justify the question of a more suitable location than the present one being carefully con- sidered. The field instruments and others of a portable nature have been most carefully looked after by Mr. Motherwell, who has kept a careful record of their movements. This work has become, with the increase in the staff and in the number of instru- ments, one of considerable labour and trouble and takes much of his time in the spring and fall. The Saturday open nights of the telescope for the public continue to be well patronized, the average attendance on fine nights being upwards of fifty, and much intelligent interest is manifested by many of the visitors in astronomy. This interest is further fostered by the papers presented at the evening meetings of the Royal Astronomical Society of Canada, of which the majority are given by officers of the Observatory. It may not be amiss here to refer also to the value of the work done by the members of the Observatory staff in the afternoon or technical lectures given alternately with the evening ones. These lectures and papers presenting in most cases original work in different lines of astronomy have been of great value, not only in keeping us acquainted with each other's work but also in encouraging researches along original lines which have been frequently of distinct value to science. The following papers by members of the staff of the Astrophysical Division have been published since the date of the last report: 1. The spectroscopic Binary L Orionis, by J. S. Plaskett and W. E. Harper, Astro- physical Journal XXVIL, p. 272, May, 1908. 2. Effect of increasing the slit-width upon the accuracy of Radial Velocity Determinations, by J. S. Plaskett, Astrophysical Journal XXVIII., p. 259, Nov., 1908. 3. The spectroscopic Binary \f, Orionis, by J. S. Plaskett, Astrophysical Journal XXVIII., p. 266, November, 1908. 4. The Orbit of t Orionis, by J. S. Plaskett, Astrophysical Journal XXVIIL, p. 274, November, 1908. 5. The Astronomical and Astrophysical Society of America, by J. S. Plaskett, Journal of the Royal Astronomical Society of Canada II., p. 255, September-October, 1908. REPORT OF THE CHIEF ASTROXOMER 151 SESSIONAL PAPER No. 25a 6. The Keduction of Cadmium by Mercury and the Electro-Motive Force of Cadmium Amalgam, by R. E. DeLury and G. A. Hulett, Journal of the American Chemical Society, volume 30, No. 12, p. 1805, December, 1908. 7. Comet 1908 (Morehouse), by R. M. Motherwell, Journal of the Royal Astron- omical Society of Canada III., p. 28, January-February, 1909. 8. The Orbit of 6 Aquilse, by W. E. Harper, Journal of the Royal Astronomical Society of Canada VIL, p. 87, March-April, 1909. Besides the above the following papers are to appear shortly, the work on them having been completed and sent to the publishers: 9. Camera Objectives for Spectrographs, by J. S. Plaskett, Astrophysical Journal, May, 1909. 10. The Spectroscopic Binary ft Orionis, by J. S. Plaskett, Astrophysical Journal, July, 1909. 11. The design of Spectrographs, by J. S. Plaskett, Journal of the Astronomica r Society of Canada, May-June, 1909. In addition to the above the Astrophysical Division have sent in the titles of the following seven papers to be read before the Royal Society of Canada at their meet- ing, May 25, 1909 : 12. A new Single Prism Spectrograph, by J. S. Plaskett. 13. Slit width and Errors of Measurement in Radial Velocity Determinations, by J. S. Plaskett. 14. The spectroscopic Binary ft Orionis, by J. S. Plaskett. 15. The System of c Herculis, by W. E. Harper. 16. Aberration of a Stellar Camera Objective, by R. M. Motherwell. 17. Convection and Stellar Variation, R. E. DeLury. 18. The Orbit of a Corona? Borealis, by J. B. Cannon. In general the work represented by these papers will appear in detail below, ar- ranged sometimes in a little different form, and including as a rule the whole of the original measurements and data which were abbreviated or left out in the published papers. THE SPECTROGRAPHS. During the year just passed the Ottawa spectrograph, illustrated and described in the 1907 report, has been used almost entirely, the new single-prism spectrograph not having been ready for service until about March 1, 1909. The former instrument has been used mostly in the single-prism form, the three prisms having been used only for some plates of ft Orionis and a few others. The spectrograph has not been changed in any way since the last report, and its performance has continued satisfactory. Nothing further need be added about this instrument, except that towards the close of the year the Zeiss Tessar objective of 300mm. focus, referred to in the last report, was temporarily mounted for the purpose of continuing the tests on the effect of slit- width on errors of setting so far as applies to a dispersion of three prisms with a short focus camera. This mount will be placed in a permanent form as soon as time can be found in the workshop, and used on solar type binaries too faint to be obtained with the long fdcus camera. Before proceeding to describe the new single-prism spectrograph, which was briefly referred to in my last report, it has seemed desirable to enter more fully than was there done into the principles on which its design was based, and for this purpose I can not do better than give here a paper on ' The Design of Spectrographs,' which I read at an afternoon technical meeting on May 25, 1908, and which will appear in the May-June number of the Journal of the Royal Astronomical Society of Canada. 152 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 THE DESIGN' OF SPECTROGRAPHS FOR RADIAL VELOCITY DETERMINATIONS. Read before R.A.S.C., May 28 3 1908. ' The subject of spectroscopy is so broad that one can not hope in a single paper to do more than touch upon a single aspect of it, and, even then, one must further limit his treatment to a particular application of this phase. Consequently, I propose to present some considerations bearing upon the design of spectrographs suitable for the accurate determination of stellar radial velocities. This branch of spectroscopy is comparatively new and is still probably only in the experimental and tentative stage. The present practice in this line has, however, reached a certain uni- formity and the general theoretical principles governing the design of spectroscopes may be applied to the case under consideration, modified, of course, in many ways by the experience of the various observers. The question is one of a judicious combina- tion of theory and experience, and I propose to present my own views, founded, of course, on theoretical considerations, but modified partly by the practice of other spec- troscopists, partly by my own experience in the work and by the results of special investigations bearing on the most suitable form and dimensions of the instrument. ' The determination of the radial velocities of stars by means of the spectroscope is one of the most exacting of astronomical investigations, and requires the closest atten- tion to all details to ensure accurate values. This will be more readily recognized when the smallness of the displacement of the spectral' lines on which the velocity depends is known. Thus, in the Ottawa Spectrograph a velocity of 20km. per second, which is greater than the average velocity of the stars, causes a displacement at Hy, the centre of the measurable range, of about ^2700 inch for 'the single-prism, and about %oo inch for the three-prism form of the instrument. The accidental errors arising in the measurement of this displacement, in spectra with good lines, are, however, not so much to be feared as systematic displacements of the lines as a whole, of which no evidence is given in the measurements, caused by flexure of the parts of the spectro- graph, by temperature changes in the prisms and lenses and also in the metal frame, by faulty adjustment of the focal positions of camera and collimator, as well as by numerous other causes. Some idea of the magnitudes of these displacements may be gained from the following figures. An hour's exposure in one of the modern spectro- graphs introduces flexure displacement equivalent, in some positions of the telescope, to a velocity of 10km. per second. A change of temperature of 1C. in the prism dis- places the lines by about 20km., which may be increased further by the expansion of the metal parts. An inaccuracy in the focal setting of the camera of only 0-1 mm. ^50 inch, may, when combined with poor guiding, cause a displacement of about 5km. It does not follow that such displacements necessarily cause a corresponding error in the velocity as they may be compensated for, partially at any rate, by a similar dis- placement of the comparison lines. But the possibility remains, and inaccurate results can only be prevented by constant and careful attention to all details. It becomes, therefore, a question of equally great importance with proportioning the optical parts to give accurately measurable spectra in the shortest possible exposure time, to so design the whole instrument that systematic errors due to the above or other causes may be provided for and eliminated as far as possible. The design of a spectrograph may be most conveniently attacked under two sep- arate headings: 1. The character and proportions of the optical parts. 2. The mechanical connection of these parts into a symmetrical and stable whole, with suitable auxiliary devices for controlling the temperature, applying comparison, &c. 153 SESSIONAL PAPER No. 25a The Optical Parts. ' Up to the present, prisms of dense flint glass have been the sole dispersing medium used for radial velocity work. Gratings, so useful in other branches of spectroscopy, have not yet been applied in this work, chiefly on account of the division of the incident pencil into a number of spectra with the consequent loss of light, and also on account of the difficulty of maintaining their position invariable without distorting the sur- face. Prisms have very decided advantages over gratings in this respect as, when set at minimum deviation, a small angular rotation of the prism will scarcely displace the spectrum lines, while with a grating the angular displacement of the lines is double that of the prism. The optical parts of a spectrograph are then : 1. The slit, whose width is usually between 0-025 and 0-051mm., one and two thousandths of an inch, on which the star image is condensed by the telescope. 2. The collimating lens placed at its focal distance from the slit and consequently rendering the incident pencil parallel. 3. The prism or prisms placed at minimum deviation for some particular wave-length usually near Hy. 4. The camera lens which forms an image of the spec- trum on the photographic plate. ' As the terms dispersion, resolving power, purity, &c., will be frequently used and as the prism angle, thickness of base, c., require computing, it seems preferable to give here a short synopsis of the theory involved and the formulae used, particularly as these are not readily available in a suitable form or collected together in one place. 'When a pencil of parallel white light is incident upon a prism, the direction is changed, the light is deviated, and it is also decomposed into its constituent colours forming a spectrum, the wave-lengths of the light giving rise to these colour-sensa- tions, diminishing as you go from red to violet. The fundamental formula determin- ing the direction after refraction is, i being the angle of incidence, r of refraction, sin i = fi sin r. jj. is the index of refraction which varies for different materials and for different wave lengths in the same material, increasing as the wave length diminishes. In all spec- troscopes the prisms are used at the position of minimum deviation, which, it may be easily shown, requires the angles of incidence and emergence to be equal. The dis- cussion will therefore be confined to this particular case, resulting in a considerable simplification. A + e =180 A e + 2r = 180 _ A ...r:-; = a + & ; a = &, A + , i = a + r = - , and as sin i = fj. sin r, 4? . A + e sin - . J sin - 2 . Fig. 1. If a is aperture of incident pencil just filling prism, I = a sec i. t = 2 I sin = 2 a sec i sin . 2 2 154 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 ' If 6 the deviation and /j. the index are given to find A or the angle of the prism, A + f) A sin - - = fj. sin and reducing and simplifying sin - 2 A = 2 sin" 1 ' The dispersion of a prism is usually defined as the ratio of the change in deviation dO to the change in wave length or-j . As the deviation varies with the index of refrac- u A tion and as the latter varies with the wave length we may put d = dQ^ d^ bijt d A d fi d X A + $ * . A sin - 2 9 A n . A - sin 2 sin - 2 2 ' d u A + 6 cos i PflS COS A A 2 sin - 2 sin - I/I - sin 2 * / . 4' \/! - j 2 sm- - , o? ^ 2 sin i 2 , also - = - - = - tan t. aw W u. ' To obtain we require a relation between X and p.. The simplest is obtained from d A Hartmann's interpolation formula. Y\Z an " consequently A ) - d 6 dO d i c 2sm 2 V- ~ n . Z A \! - <"- sm " g- ' Let us now consider resolving power or the ability of the prism to separate lines close together in the spectrum. Lord Eayleigh has shown, in the case of the image of REPORT OF THE CHIEF ASTRONOMER 155 SESSIONAL PAPER No. 25a an infinitely narrow slit produced at the focus of a telescope lens, that the linear dis- tance of the first diffraction minimum from the principal maximum is given by the equation. m A / where a is the aperture and f the focus of the lens and m is a constant, 1-0 for rec- tangular and 1-2 for circular apertures. J _ m ^ f" ~^ ^ is then the least angular distance at which two rays can be seen separated. Calling the angle dQ we have m A d 6 = a For the case of a prism we have ^ a = I cos i, t = 2 I sin a cos i d /* Combining we get the minimum condition of resolution m A ' = ^/ ' a fi Again, omitting the constant m, we have *-!**U, a a a and multiplying by j ; we get d_6 d_ft _ J_ where ^r is the minimum value which permits resolution of close lines. -= or the a A d A ratio between the mean wave length of a pair of lines which can just be resolved in a spectroscope and the difference in wave length between the two components is called the resolving power of the spectroscope and is usually designated by the letter R. ds ' The linear dispersion -=-j- where f= focal length of camera is d s dO R ' The resolving power R refers to infinitely narrow lines through an infinitely nar- row slit. When, as necessarily occurs in practice, neither of these two conditions holds, we speak of the purity of the spectrum or the practical resolving power for wide slit?. Schuster has given a simple expression for the purity which is always a fraction of the theoretical resolving power R. This expression has been elaborated by Wadsworth. 156 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 and later stilt Schuster has given tables for determining the purity. But as no appre- ciable error will be introduced in the relative values used in this work, it has seemed preferable to adhere to the simple form. If d = slit width and \j/ = angular aperture of the collimator = , the Purity P= , . f d \j/ + X ' We have now obtained all the formulae necessary to compute the data for any opti- cal system and to compare the efficiency of different forms of spectroscopes. To take a concrete case, which is more applicable for our purpose than a general discussion, I propose to consider the question of the most suitable aperture to be given a single- prism spectrograph which is being constructed for the Dominion Observatory. The present spectrograph, which is arranged to be used with either one or three prisms, has a collimator of 35mm. aperture, 525mm. focus and two cameras, one for each form of 525mm. focus. It performs excellently for both purposes, but when, as often happens, both single and three prisms are required 011 the same night, the change from one form to the other is somewhat tedious, requiring 15 or 20 minutes, and moreover, what is far more important, such change involves uncertainties as to the temperature condi- tions of the optical parts and therefore corresponding uncertainties as to the accuracy of the velocities' obtained. a 1 In order to fill the collimator lens completely with star light its aperture ratio -> must be the same as that of the equatorial. The aperture ratio of the Ottawa telescope is 1 to 15, consequently the focal length of the collimator must be 15 times the aper- ture. This aperture is limited on the lower side by the condition that sufficient purity must be obtained, purity being proportional to the aperture at a practicable width of slit, to so separate lines and blends of lines that sufficiently accurate identifications of lines and the true wave lengths of blends may be obtained. It is limited on the upper side by the difficulty of obtaining homogeneous prisms of large size, by the increased absorption of such prisms, and by the increased size and weight of the instrument. In all the spectrographs used in radial velocity work the apertures lie between 30 and 51mn?., and these see:n to be about the practical limits. It remains to determine the most suitable. ' The basis of the discussion* rests upon the results obtained for the effective dia- meter of the star image given in my paper on ' The Star Image in Spectroscopic Work,' No. II, which was read here last fall and published in the Astrophysical Journal, March, 1908. The results of a number of experiments, photographs of star images, spectra and trails, went to show that only very rarely is the effective diameter of the image less than 2 sees, of arc (about 0- 055mm.) at the focus of the refractor. Generally the diameters of images and the widths of spectra and trails are considerably greater, increasing to over 0-lmm. with longer exposures. As the theoretical diameter of the central disc is only 0-57" (about 0-015mm.) and, as the condensing system of visual objective and photographic correcting lens is practically perfect, the enlarge- ment in diameter is undoubtedly due to atmospheric disturbances. These consist pro- bably partly of a blurring or spreading out of the central disc and partly of small displacements in all directions from its mean position. In consequence there results considerable loss of light at the slit jaws with the widths usually employed, and further experiments showed that the proportion transmitted varied almost directly with the width until this reached 3 or 4 sees. I reproduce below part of the table for slit trans- mission given in the paper referred to: * An able discussion of this subject on somewhat similar lines, to which I am much indebted, has been given by Newall (M. N. 65, p. 608). REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a SLIT TRANSMISSION. 157 Slit Width. Comparative exposure for equal intensity of spectrum. Linear mm. Angular sees. Observed. Corrected for loss by diffraction. 0-025 O'OSl G'076 0-102 0-91 1-82 2-73 3 64 100 40 27 25 100 50 35 32 ' This table shows that if the slit width can be increased the exposure is propor- tionally diminished, double the slit width halve the exposure, which means, of course, i increase in the output and in the practical range of the equipment, But on the other hand, a widening of the slit, other conditions remaining unchanged, decreases the accuracy of measurement of the resulting spectra. This loss of accuracy is due to two causes: first, diminished purity rendering uncertain identifications and wave lengths of blends; second, increased diffuseness of the spectral lines rendering mea- surements more difficult. We will take up these two considerations separately and find under what conditions the slit may be widened without loss of accuracy. ' The equation for purity of spectrum, P = - R, shows that the purity is d\l/ + A almost proportionally diminished as the slit width is increased as d^ is, even for slit 0- 025mm., nearly ten times A. To increase the purity of a spectrum only two courses are open to diminish the slit width or increase the resolving power. As we wish to widen the slit the resolving power of the spectroscope must be increased, which may be done in three ways. A d 1. By increasing the aperture of the prism or prisms R = -y-r = a -yy or R varies directly with the aperture. 2. By increasing the number of prisms. 3. By shifting the region of spectrum under observation towards the violet. The resolving power varies inversely as the cube or slightly higher power of the wave length. This will be seen directly when we compute resolving powers, but it follows at once by differentiating Cauchy's form of dispersion formula. D ri /u. = J + y2 + y4+.... or simply /* = A + T2 _ d X ~ Ji 3 ( The use of the second method increases the dispersion which is usually not allow- able on account of the proportional increase of exposure time entailed. The third method can not be used with a refractor and glass prisms on account of the strong absorption of ultra violet light by the glass of the lenses and prisms. With a reflector and a quartz or ultra-violet glass spectrograph it might be applicable. We are there- fore practically limited to the use of a larger prism and consequently larger collimator and camera lenses. 158 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 ' The size of prisms in use in radial velocity work, as previously stated, lies between about 30 and 51mm. Prisms of 51mm. aperture are successfully used in the Yerkes Spectrograph, but Frost's experience as also that of Hale in large spectro-helio- graph prisms shows that the limit is nearly reached. ' In discussing the necessary conditions for using a wider slit, let us take as an example a comparison between the efficiencies of single-prism spectrographs of 35mm., the aperture of the present instrument, and 51mm. aperture, the latter having been decided upon, after careful consideration, as the aperture of the new instrument. A spectrograph of such aperture, outside of considerations of the homogeneity of larger prisms, is the practical limit as regards size and weight that can be attached to a 15-inch equatorial. ' The glass generally used for the prisms is Jena glass 0-102, Dense Silicate Flint, and this was chosen for the spectrographs here. It is very colourless considering its density and dispersion. The indices of refraction of the particular melting from which the present prisms were made, as furnished by the makers, are as follows : Wave Length. Index of Refraction. 00006563cm 1-6413 1-6467 1-6603 .00005893cm .0000-1862 cm ' From these values substituted in the Hartmann formula p = p. + c A-AO the values of the three constants /x , c and A - A = -00002190. It = 1-61146. log c = 6- 115595. 'From these constants were calculated for a number of wave lengths p and- . From "A d ~- , R was obtained for prisms of 35 and 51mm. aperture, and of refracting angle 63 50', this being the angle required to deviate the ray at minimum, A 4415, 60. The formulae used were previously derived and are : d /< A + 6, . J a A . sin 23 2 Wave Length. " dM lA .K Prism 35 mm. R Prism 51 mm. 4862... 1-6603 l2 f 14420 21010 4550 1'6667 2343 18470 26910 4415 ] 6701 2636 20780 30280 4341 l'672l 2822 22250 32420 4102 1 ' 67!)6 3490 27520 40100 4000 l'833 3983 31400 45750 3970... 1-6848 4119 32380 47180 RUI'ORT OF THE CHIEF ASTKOXOMER 159 SESSIONAL PAPER No. 25a ' The resolving power for the two apertures obtained, the purity of spectrum for different slit widths is readily calculated from P = -7- r - ^ in this case, being a V 4- X M.5 or -0667. The results are given in the following table for the wave length 4341 or Hy, this being the usual central ray. PURITY OF SPECTRUM. Slit Width. Prism 35 mm. Prism 51. mm. 0025 45% 6697 040 3114 4537 051 : 2518 V 367O 063 ... . . 2084 3036 076 1755 2558 ; These figures show that with the larger prism the slit may be made 50 per cent wider and still have practically the same purity of spectrum, and consequently the same accuracy of velocity determinations. ' The slit transmission table previously given showed that an increase in slit width of 50 per cent when below 0-076mm. increased the quantity of star light transmitted hy nearly 50 per cent ; consequently, other conditions being equal, half as many more spectra could be made in a given time. But an increase in the size of the prism means also an increase in the quantity of light absorbed by the glass of the prism, although the amount reflected will be the same. We can obtain an accurate knowledge of the quantity of light absorbed in the two prisms of O. 102' glass from VogePs experiments (Astrophysical Journal, V., p. 75), who showed that Hy light transmitted through 100mm. of O. 102 glass suffered absorption of about 47 per cent. The absorption for -prisms of 35 and 51mm. aperture, average length of path 39 and 57mm. respectively, may be readily calculated by the formula I I I K u , where # is thickness of glass d:or which absorption is required, a is thickness for which percentage transmitted is K, I intensity of incident, 7 X of transmitted beam. We obtain for prism of 35mm. aper- ture 78 per cent, of 51mm. aperture 71 per cent transmission. If 100 be intensity of incident pencil for small prism, then 150 will be intensity of pencil giving equal purity with large prism. After transmission intensities will be 78 and 150 x -71 or 106-5, respectively, and the required exposures will be inversely proportional or as 3 to 4, a very considerable gain. Even when the slight additional absorption in the thicker camera and collimator lenses is considered a substantial saving of time will result by the use of the larger prism. ' We have tacitly assumed in the foregoing discussion that a decrease of purity entails loss of accuracy in the velocity values. This is undoubtedly true for complex spectra such as those given by solar or allied type stars, spectra in which are hundreds of lines and in which every decrease in purity means increased uncertainty in the wave lengths of the more complex blends of lines thereby produced. In the case of early- type stars, however, such as those of the hydrogen or helium groups, where there are only few lines, and these single, there can be no trouble with blends, and the question of the purity of the spectrum has not so much weight. On such grounds there would be no material advantage in using the larger aperture. However, a consideration of the second effect produced by widening the slit the increased diffuseness of the spec- tral lines will show a similar advantage for the larger aperture even where purity does not come into question. 25a 13 160 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 ' This may be best shown, as before, by considering a special case and we may take the same example with advantage. The present single-prism spectrograph has a colli- mator objective of 35mm. aperture and 35 x 15 or 525mm. focus. The camera has a focus of 525mm., and therefore the image of the slit on the plate will be of the same size, and the minimum width of line will be the width of the slit. The new spectro- graph will have a collimator of 51mm. aperture and 51 x 15 or 765mm. focus. The camera will be of about 455mm. focus. Hence the image of the slit on the plate will be diminished in the proportion of 455 to 765 or about %. If the camera were of the same focus as the one now in use, 525mm., the image of the slit would be diminished to about Ko. Hence the slit can be made in the one case %, in the other J %, the width with the present spectrograph, and have the lines of the same width, and consequently equally accurately measurable. The gain in efficiency is thus about equal under the latter consideration and that of the maintenance of equal purity, and we may there- fore consider that a decided advantage may be obtained in stars of all types by in- creasing the aperture of the prism. Such conclusions are, of course, subject always to- the test of actual use under similar external conditions before they can be accepted as final. ' However, some experiments that I made here last winter on the effect of widening the slit upon the accuracy of velocity determinations* substantiate the above conclusion, and I will therefore give a short summary of some of the results reached. As previously stated, when the slit is widened, the purity is diminished and the lines become broader and more diffuse. To simplify the investigation, the question of the effect of purity was eliminated by qhoosing a star, ft Orionis, for the test whose lines are single and moderately sharp. There remains, then, only the question of the effect of the increasing breadth and diffuseness of the lines on the accuracy of the measures. Evidently such a question can only be settled by making and measuring a number of spectra at each slit width. Six plates were made for each slit width 0-025, 0-038, 0-051, 0-076mm. for two dispersions, (a) single-prism 525mm. camera, (b) three-prism 525mm. camera and six each at slit widths 0-025, 0-051 and 0- 076mm. for a dispersion of three prisms and camera of 275mm. focus. In all 66 plates were made, of which I have to thank Mr. Harper for measuring 18 and thus lightening the considerable labour in- volved. Owing to the different dispersions, different lines were measured in the three sets, but as the main dependence can be placed on the three lines Mg A.4481-400, He A4471-676, Hy 4340-634, the results from these three lines only are given. Com- putations using all the star lines measured were also performed without, however,, changing the conclusions reached. ' There are evidently two kinds of error to be considered, accidental and systematic. Under the first will be considered the accidental errors of the setting of the microscope wire on the individual lines in a plate, resulting in a mean velocity for that plate- differing from the true velocity in a greater or less degree depending upon the quality of the lines. The systematic error of a plate is the displacement of the star lines as a whole with respect to the comparison lines. This may be due, as previously stated,, to one or more of several causes change of temperature, flexure, faulty adjustment or aberrations in the optical train, &c. As the lines are in general equally affected, such displacement will not be apparent in the measure of a single plate. It is only by comparing the velocities of a number of plates of a. star of constant velocity that such an error can be detected. ' To compare the accidental errors for the different slit widths it will be necessary,, to prevent systematic displacements from affecting the result, to treat the measures for each of the six plates for one slit width separately, to obtain the residuals from the mean velocity of each plate and finally the probable error of measurement of an aver- age star line from these residuals. Some idea of the relative magnitude of the sys- * Since published in the Astrophysical Journal, Vol. XXVIII, p. 259. REPORT OF THE CHIEF ASTRONOMER 161 SESSIONAL PAPER No. 25a tematic errors may be obtained by treating the- velocities from each of the six plates. However, this result will not be that due to systematic error only, as the velocity from each plate will also be affected by accidental errors. The results of the measures and computations are given below: PROBABLE ERRORS. Dispersion. Slit Width. Accidental Prob. Error, Average Line. Systematic Prob. Error, Single Plate. Single Prism 0'025 + 4'5 km. +1'7 km. 525 mm. Camera 038 051 24 23 2 7 3'0 Three Prisms ... 076 0'025 43 + 23 7'7 +15 >25 mm. Camera 038 051 21 2'5 1-3 0'7 Three Prisms . .... 076 025 21 +2'9 0'9 +2'1 275 mm. Camera 051 '076 29 3'8 3-0 2'9 ' These results were to a considerable extent unexpected. The great difference in the apparent quality for measurement of the spectra made with slit 0-025 and -076mm., especially with the single-prism, would lead one to expect a marked increase in the errors of setting, but this is not very distinctly shown, not at all in the higher disper- sion. The systematic errors, however, are very markedly increased in single-prism plates, so much so as to prohibit the use of slits wider than 0-051nim. In a higher dispersion spectroscope this increase has disappeared, and, so far as the rather small number of plates shows, it is slightly more accurate in the case of dispersion (&) to use slits 0-051 and 0-076mm. than slits 0-025 and 0-038mm. It is evident that these results corroborate the conclusions previously reached, by showing that increase in resolving power removes or diminishes the loss of accuracy when the slit is widened. Consequently, with the 50 per cent greater resolving power and the 60 per cent greater ratio of collimator to camera focus, it is probable that the slit-width may be increased 50 per cent without affecting the accuracy of the results and with a corresponding increase in the output. Mechanical Design. ( The question of the most favourable dimensions of the optical parts having been discussed, there remains the mechanical structure connecting these parts into one stable whole. Owing to the attachment of the instrument to a moving telescope and the consequent varying direction of gravity on the parts, the prevention of flexure is one of the most difficult of the problems to be overcome, and this is especially the case where the instrument is to be attached to a telescope of moderate size, where its weight can not exceed a certain small limit. The weight of our spectrograph com- plete with temperature case, attaching truss, &c., can not much exceed 100 Ibs., and the problem is consequently a much more difficult one than in the case of the Yerkes equipment, for example, where the spectrograph weighs about 500 Ibs. Most of the early and some of the recent spectrographs have lacked sufficient stiffness and stability to prevent line displacements due to flexure of the parts. A displacement of the camera and plate of only one one-thousandth of an inch is equivalent in a single- prism spectrograph to a velocity of about 50km. per second. It is evidently a difficult 25a I3i 162 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 matter in the extended form of a single^prism instrument to reduce this flexure to an inappreciable amount. No material is perfectly rigid and when we consider that even its own weight deforms the strongest material available, the difficulty of the problem will be realized. ' Until very recently all spectrographs were attached to and overhung the end plate of the telescope and thus, like a beam fixed at one end, were subjected to the maximum amount of flexure. An improvement in the principle of attachment was applied at the Lick Observatory recently, in which the spectrograph proper is made self-contained and is held in an independent cradle at two points of support. It is thus like a beam supported at both ends and the flexure is thereby much reduced. ' The original spectroscope belonging to the Observatory was by Brashear of an adjustable universal type and was not, for this very reason, suitable for radial velocity determinations. Braces were added to stiffen the frame as much as possible, but it could not be freed from flexure. Many of the results obtained were uncertain and its use was discontinued as soon as a new combined one and three-prism spectrograph, designed by myself and very satisfactorily constructed by Mr. Mackey in the Obser- vatory workshop, was completed. ' This instrument, whose general form is readily obtained from the figures, page 78 in my report to the Chief Astronomer for 1906-7, has many original features, has given excellent satisfaction and produced reliable results. It is, as will be noticed, a form of the first class mentioned attached only to the end plate of the telescope. It was designed and partly constructed before anything was learned of the new type. More- over it was desired for the sake of economy of time and money to combine single and three-prism instruments in one (since found by experience to be a mistake), and this could not be advantageously effected in the new form. ' The form of truss designed has some advantages over previous instruments, and has probably less flexure than any other of the same type and weight. The main difference lies in the close grouping of the triangular truss at the lower end and the addition of the substantial diagonal brace, which serves the two purposes of stiffening the outer end of the prism box and lower end of the camera when used in three-prism work, and of tying the outer end of the camera when used with a single prism. The maximum flexure of the three-prism instrument is equi- valent to l-8km. only, while the maximum flexure of the modern Bonn three-prism instrument, the only one for which data have been published, is about 70km. For an hour's exposure with the Bonn instrument there is a flexure of 7km., while a similar exposure with both single and three-prism forms here shows no appreciable flexure. The maximum flexure with our single prism is much greater, about 100km., equivalent to a linear displacement of about 3 /4oo inch. This great difference in the two forms is due to two causes. First, to the threefold greater kilometre value for the same linear displacement. Second, to the much more extended form of the single-prism instru- ment. Calculations have shown that the amount of flexure is nearly that caused by the actual extension and compression of the truss members due to their own weight, and consequently it can not be avoided or imich reduced in this form of instrument. However, the flexure occurring during a two hour's exposure is only slight except at such great hour angles as are rarely used. ' Both forms of instrument are frequently required on the same night, for stars of varying brightness and type. The time lost in making the change from single to three prism or vice versa, and the uncertainty in the temperature conditions prevailing after the change, close temperature regulation being equally as important, perhaps more important than avoidance of moderate flexure, were considerations leading to the decision, which had the approval of Dr. King, to design and construct a separate single- prism spectrograph, with separate temperature control and attaching stand, so that 'he (-Iiiuigo could !> made in a minute or two, and without disturbance of tempera- ture. REPORT OF THE CHIEF ASTRONOMER 163 SESSIONAL PAPER No. 25a ' Besides using a larger prism for the reasons fully entered into above, the oppor- tunity was taken of changing the mode of attachment to the telescope. Curtiss, of Ann Arbor, designed a form of single-prism instrument modelled after the Lick pat- tern, which has two points of support, one near the slit and the other near the base of the prism. The spectrograph proper consists of a triangular brass box with angles of about 120, 30, 30. The prism is at the obtuse and the slit and camera at the acute angles of the triangle. The camera end hangs out unsupported and flexure will still occur though in a much diminished degree. ' The form I have designed and am now having constructed in the workshop fol- lows that of Curtiss in that it is of the box form, but the design and construction of the box and the method of attachment to the telescope are different. The box is made of hard cast-steel plates (saw steel) much stiffer than brass, is rigidly braced and cross braced, and is provided with three points of support in a cradle of T iron attached to the end plate of the telescope. Two of the points are similarly situated to those of Curtiss, while the third acts near the camera end. The two first are attached by a kind of universal joint, so that no strain can be induced in the box by any bend- ing of the cradle. The third support, near the camera, consists of a pair of counter- balancing levers, one on each side of the box, arranged to equalize the pressure on the three supports in any position of the telescope without it being possible to ever induce any strain in the box itself. By this means it is believed that no measurable or even noticeable flexure will occur. ' A simple triangular box of this form without projections of any kind is much more readily adapted for temperature regulation than the complicated shape of the regular truss form. Moreover, any stratification in the temperature case is much less likely to occur, and if it does, can not do nearly so much harm as if it were acting on only one member of the truss. A further improvement will be the introduction of a non-conducting material, such as vulcanized fibre in the supporting arms between the cradle and the box, so that heat \vill not be conducted away at these points and unequal temperature and possible distortions take place. ' In the present spoctrograph, conduction through the arms of the truss is so great as to cause a gradual drop of the temperature in the prism box, as the outside tempera- ture falls, of about 0-1C. every one or two hours. The distance between the spectro- graph box, which will be entirely covered with thick felt, "and the inside of the felt- lined outer case will be uniform, the heating wires will be uniformly distributed, and consequently little difficulty with inequalities of temperature should result. ' Although until the instrument is completed and tested, no definite statement can be made, I have little doubt that the new spectrograph will be a considerable improve- ment over the present or any existing single-prism instrument.' TflK NEW SINGLE-PRISM SPECTROGRAPH. The Optical Parts. After the dimensions of the optical parts of the new instru- ment had been determined as above they were ordered from the J. A. Brashear Co., in the early part of 1908. Some correspondence was carried on in regard to the ' Isokumatic ' Collimator objective in reference to the yellowish colour of the middle component. It was, how- ever, decided to use it in preference to the less absorbing ordinary objective, on account of the flatter colour curve given by the former. Consequently an ' Isokumatic ' of 51mm. (2 inches) free aperture and 765mm. focus was ordered and received at the same time as the other optical parts, about the end of last March. Although no direct tests have as yet been made, there is no question of its being a first class objective, as otherwise the good definition now obtained would not be possible. The prism of Jena glass O. 102 had its angle 63 30' computed, so that the central ray for this instrument A.4325 had a deviation of 60. The length of the side of the prism was made 110mm., 164 9-10 EDWARD VII., A. 1910 so as to transmit the full pencil from the collimator, and the height 57mm. in order that any effect produced by pressure or unequal temperature of the supports might be minimized. The prism is a beautiful piece of glass and the tests have shown it to be of first rate optical quality, and fears as to its possible lack of homogeneity groundless. The camera objective, owing to the excellent performance of the Brashear Single Material in the previous instrument, was chosen of the same type and is of 57mm. aperture, a sufficient margin above 51mm. to transmit the full usable pencil, and 455mm. focus. It was tested soon after being received and, although it gave a flat field, the definition was not as good as that given by the original objective, and a pre- liminary test showed this to be .due to spherical aberration. The objective consists of two widely separated converging elements of very light crown glass, and consequently the resulting positive aberration can only be removed by departure from spherical surfaces. The amount to be removed in the case of the original objective of 45mm. aperture and 525mm. focus was quite within the possibilities of ordinary figuring, but when the aperture ratio is increased to so large an extent as from f!2 to f8, it becomes a much more difficult problem to deal with. In this case it was only after the intro- duction of a special method and with the great personal skill of Mr. McDowell in figuring, that the aberration was finally removed, and the objective gave practically perfect -definition and a widely extended flat field. A full description of the tests, with the plotted fields resulting from different objectives, is given in full in another place. The Guiding Telescope. Instead of reflecting the light used for guiding down a tube parallel with the collimator and there further reflecting it to the guiding teles- cope so placed as to also receive light reflected from the front surface of the prism, the guiding telescope has in this case been placed about 15cm. above the slit, where star light coming from the inclined speculum-metal jaws is reflected by a right-angled prism to a small objective placed at its focal distance along the optical path from the slit. The resultant parallel pencil is then received by the bent guiding telescope shown, Fig. 2, which can be rotated to any convenient direction. Two reflections are hereby avoided, resulting in some saving of light and probably better definition. It had been found in the previous instrument that the method of guiding by light reflected from the front prism surface was never used, and consequently in the new spectrograph this needless complication was omitted. It may be said, however, that the position of the guiding telescope is in some positions of the equatorial, not quite so convenient as if it were lower down. The Comparison Apparatus. Experience has shown that in actual work more than one metal is never used as electrode, and consequently the rotating wheel with four sets of electrodes used previously has been omitted here, and one pair of adjust- able electrodes of the alloy of iron and vanadium, whose spectrum is exclusively used for comparison, has been substituted. These terminals are mounted on a brass plate which swivels on two points attached to the top of the guiding telescope, and when not in use is simply turned back upon the latter, thus leaving the star light unobstructed. Directly below the terminals in the optical axis is screwed the short tube shown, in the upper end of which is a piece of ground glass and in the lower a small condensing lens with an angular aperture twice that of the collimator. Both of these are adjustable and ensure in every case a uniform pencil of spark light incident upon the collimatoi objective and prism. Slit and Slit Diaphragms. The slit is of the Huggins type of reflecting slit, with polished speculum metal jaws inclined at an angle of 3i, so that the reflected pencil of star light and consequently the prism which intercepts it is entirely out of the way of the direct pencil. One jaw is fixed and the other movable micrometrically, a single divi- sion representing -001 inch (025mm.). The slit has a tangent screw slow motion to enable it to be placed exactly parallel to the refracting edge of the prism, and is very PLASKETT ASTROPHYSICS. FIG. 2 New Single-Prism Spectrograph. 25a-p. 164 PLASKETT ASTROPHYSICS. FIG. 3 New Single-Prism Spectrograph. REPORT OF THE CHIEF ASTRONOMER 165 SESSIONAL PAPER No. 25a rigidly attached to the end of the heavy collimator tube. To the end of this tube is also screwed the attachment holding the sliding diaphragms, which serve to limit the star and comparison spectra. Rectangular openings of the proper width, in this case a single opening 0-4mm. for star spectrum and two openings l-5mm. separated by a tongue 0-45mm. for comparison spectrum, are placed directly opposite one another on a plate which is moved by means of a knurled wheel transversely between stops across the slit. To expose the spark spectrum all that is necessary is to turn down the spark apparatus, turn the knurled wheel above mentioned about a quarter turn, and close the switch which controls the current through the step-up transformer used for pro- ducing the spark, this switch being on the telescope tube about a foot above the spark apparatus. To change back to star spectrum the operations are reversed, the whole cycle occupying only about ten seconds. The Mechanical parts. As outlined above the instrument consists essentially of two parts 1. A rigid, hollow, triangular shaped, steel box containing at the obtuse angle the prism, and at the two acute angles the slit and plate and comprising the spectrograph proper; 2. The T iron frame or cradle attached to the end plate of the telescope, in which the spectrograph proper is flexibly supported, and which serves to keep it collimated without flexure of this support producing any stresses in the box itself. The Spectrograph Box. The box consists of two triangular shaped plates made of hard saw steel about l-7mm. thick forming the sides, while the edges consist of plates of the same material and thickness, 79-4mm. (34 inches) wide. In addition to the edges there are a number of internal braces and supports of the same material, well shown in Fig. 4, which gives a good idea of the construction of the box. These braces as well as the edges of the box have pieces of small angle iron securely riveted along both edges, to which the side plates are firmly screwed. These angle irons are not shown in the figure, as the frame was first put together, the angles then riveted on and finally the plates screwed to these angles and to the internal castings, the heads of the screws being shown on the side of the box in Fig. 2. It was constructed in this manner to prevent as far as possible any internal stresses in the frame of the box. In addition there are iron castings A, B, C, D, E, F, Fig. 4, planed to exactly the same width as the edges and braces. A, may be called the main casting, having a hole bored through the centre through which the principal supporting shaft passes. The two legs projecting from the triangular part are bored out to fit the collimator and camera tubes. The casting, D, is also bored out for the collimator tube and forms the end plate of the box, while the casting, F } is bored out to carry the upper end of the camera tube. C, and, E, have clearance around them and do not touch the collimator tube, the upper support being attached to the centre of C. The part, B, has the third supporting shaft screwed into the centre of each side, and also forms the connection between the box proper and the camera end. The latter is made separate, so that camera objectives of different focal lengths may be used if desired. The prism is mounted in a separate cast-iron cell, but is prevented from touching the metal at any point by facings of hard rubber about 3mm. thick, and is kept in its adjusted position by hard rubber stops. It is held firmly in this position in the cell by the gentle pressure produced by three small clamp screws passing through the top of the cell and bearing upon one of the facings of hard rubber 3mm. thick, above mentioned, resting on top of the prism. The base of the cell is surfaced flat, and rests in its compartment on one of the side plates, to which it is rigidly attached by five screws passing through slotted holes to permit of adjustment for minimum deviation. Collimator and camera tubes are provided with racks and pinions for adjustment, their position being read on millimetre scales, the one attached to the camera being provided with a vernier, reading to tenths of a millimetre. The collimator tube is provided with two clamp screws, one at the top and one at the bottom bearing, while 166 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 191O the camera tube has a single clamp screw at the front end. The pinion and clamp wheels and the scales are well shown in Figs. 2 and 3. The camera attachment, whose form and construction can be fairly well obtained from Figs. 2 and 3, is built in box form of the same material, and is firmly screwed to the casting, B, Fig. 4, it and the spectrograph box thus forming what is to all intents and purposes one continuous piece. Between the sides of the camera box, swivels the plate holder attachment which is quite similar in form to the one used with the other spectrograph. It consists essen- tially of a semi-cylinder 79 -4mm. long, 101 -6mm. diameter, pivoted along its axis- between the sides of the box to permit a wide range in plate inclination. This cylinder is constructed from a section cut from a piece of 4-inch brass tubing 1 , on the ends of which pieces of heavy brass plate are screwed and soldered, and on the plane of section is fastened the brass camera back provided with screws for clamping the holders firmly in place. The plate holder carrier has solidly constructed ways permitting lateral movement of about 15mm., enabling a number of narrow spectra to be made side by side on the same plate if desired. The axis on which the camera back rotates is pro- vided with knurled clamping wheels, while other screws moving in concentric slot:* enable adjustment and firm clamping to be effected in any desired position, read off on graduations 011 the cylinder. As will readily be seen from its design and construction and from the character of the material from which it is made, this spectrograph is exceedingly rigid and the flexure produced by changes of position, however supported, would be very small. This flexure, however, is reduced to a vanishingly small quantity by the new supporting system used in this instrument. The self-contained spectrograph box is, as has been indicated above, supported flexibly on three points in the carrying cradle. The Supporting Cradle. This truss made of lg" T steel is attached at the upper end to a heavy ring casting, which is fastened by the same three swivel bolts used for the other spectrograph to the end plate of the telescope, the mode of attachment being shown in Fig. 3, which with Fig. 4, well shows the form of the truss. It is evident that the only flexure of this truss in a direction parallel to the sides of the spectro- graph will be that due to the extension of one arm and compression of the other in each pair, and this will hence be very slight. Owing to the fact that these two pairs of trusses had to be separated about 20cm. at the lower end, to admit the spectrograph with oxitside temperature case between them, it is evident that flexure in a direction at right angles, parallel to the movement in right ascension, will be greater. This is minimized as much as possible by joining the two ends by a solid webbed casting and by introducing cross braces at the upper end of the truss as shown. At small hour angles, however, which it is desirable for many reasons to use as far as possible, the component of the weight in this direction will be very small and the flexure negligible. Even at large hour angles which arc sometimes required, the flexure cannot be great. In any case from the method of attaching cradle and box, to be presently described, no flexure of the cradle can induce any stresses in the box and the only effect of such flexure will be to slightly alter the axis of collimation of the spectrograph. This can not, however, induce any displacement of the spectral lines, not only on account of it* relatively small magnitude but also because it can occur practically only parallel to the spectrum lines and to the refracting edge of the prism, which will have no effect on the position of the line. The principal and central support -and connection between cradle and box con- sists of a shaft 1 inch (25-4mm.) diameter passing through the hole in the main cast- ing. This shaft is left the full size of the hole only for about 2mm. at the centre, so that the box is free to swivel in every direction around the centre to the extent of 2 or 3 degrees. This swivelling motion is, however, limited, by projecting points on the shaft at the ends of the hole, to one parallel to the motion in right ascension and to the slit, rotation around the axis of collimation being prevented. Consequently any flexure of the cradle can not induce any distorting stress in the box. PLASKETT ASTROPHYSICS. 25a p. 16G FIG. 4 Spectrograph Box. IlKPORT OF THE CHIEF ASTRONOMER 167 SESSIONAL PAPER No. 25a The upper supporting shaft has a transverse hole in the centre through which a pin screwed into casting C passes, thus allowing longitudinal motion parallel to the axis of collimation as well as swivelling motion in every direction. The third point of support consists of shafts rigidly screwed into the centre of each side of casting, -B. A second short shaft at each side carried by plates screwed to the cradle, as shown (Figs. 2 and 3), is placed about 2 -5cm. from the first in a direc- tion which, if produced would nearly pass through the centre of mass of the box. A lever attached to these two shafts at each side in such a way as to allow more than sufficient motion without binding, carries a counterbalancing weight, the combined resultant upward thrust of the two 011 the box being computed to equal the propor- tional part of the weight that should be carried by this support. The box is hence carried equally on the three supports without any possibility of distortional stresses occurring in it due to flexure of the cradle, the only effect of such flexure being to slightly change the axis of collimation, which at the utmost can only induce displacements of the second order in the position of the spectral lines. Temperature Control. Every precaution having been taken, successfully as will be seen later on, against flexure, there remains, as the other main cause of systematic displacements possibly more dangerous than flexure, displacement due to changes of temperature in the optical and mechanical parts of the instrument. The changes in temperature between day and night or even between evening and morning at Ottawa are considerable, averaging about 8C. for the former and 6 for the latter. In many cases the temperature in the dome becomes 10C. lower than that in the temperature case, rendering satisfactory maintenance of constant temperature in the case a diffi- cult matter. As mentioned in the two previous reports, such difficulty was experienced and the temperature in the prism box dropped gradually about 0-1C. per hour as the tempera- ture in the dome became lower. When practically the whole of the inside of the case was covered with the heating coils this drop was not so great, but was not entirely overcome. It was believed to be due to the conduction of the heat through the metal parts of the attaching truss, the collimator tube, &c., exposed to the outside air and that, although the temperature inside the case undoubtedly remained nearly constant, the temperature inside the prism box would diminish with the lowering of the outside temperature owing to the greater loss of heat through the exposed supports. To overcome this as far as possible in the new instrument all of the shafts attach- ing the box to the cradle were cut at points about 3cm. from the box, just inside the outer case, were bored out and threaded, and a piece of vulcanized fibre separating the ends about 7mm. screwed in. This fibre, seen dark on the shafts in Fig. 3, is a poor conductor of heat, prevents direct metallic conduction from the box inside the tem- perature case to the cradle outside, and the only part of the spectrograph exposed is the slit head. The temperature inside the outer case is automatically controlled by a pair of electric contact thermometers placed not, as in the previous instrument, one on each side of the prism box. but one in the front near the upper end and one at the back near the camera. Each of these thermometers controls the heating coils in the corresponding half of the outer case. It was hoped by thus arranging the thermometers and coils to keep the temperature over the whole interior of the case more nearly uniform than pre- viously. These thermometers act in exactly the same way as in the former instru- ment described in the. 1907 report. When the temperature in the case rises the mer- cury in the open capillary makes contact with an adjustable platinum wire and the resulting battery current attracts the armature of a relay, thus breaking the heating- circuit; similarly when the temperature falls the mercury recedes from the platinum terminal, the relay armature is released and current is turned on the heating coil?. In practice the regulation is very good, current in the coils as indicated by pilot lamps turned on and off every few seconds. To smooth down any remaining irrejru- 168 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 larities the whole exterior of the spectrograph box is covered with a layer of half -inch thick felt, small hinged doors being made over the indexes and scales of collimator and camera. The temperature case is in this instrument constructed of wood chiefly on account of its greater ease of construction, of its greater heat insulating power, and of the smaller danger of short circuits in the heating coils over one made of aluminum. Moreover, owing to the simple form of the spectrograph, a wooden case can easily be made amply strong. This case is made of -inch thick pine, lined inside with felt about f-inch thick and is divided into three sections, the line of junction of the body of the case necessarily following the supporting shafts. The third section, which was necessary for constructional reasons, is a small box-shaped piece at the camera end. All joints between the sections and the joints around the doors in the case, necessary for the adjustment and clamping of collimator and camera and of the contact wires in the thermometers, are carefully padded with felt to be air-tight. This case, which is shown in Fig. 5, is attached securely to the supporting cradle and does not touch the spectrograph proper, the openings around the end of the collimator tube and the sup- porting shafts being made large enough for free clearance and at the same time heat- tight by washers of felt. On the felt lining on the inside of this case is stretched about 1,200 feet No. 28 single silk covered German silver wire, arranged in four circuits of 300 feet each, two of these circuits in multiple are controlled by each of the electrical contact thermome- ters, each governing the coils in its own section of the case. This wire is distributed as uniformly as possible over the inside of the case, the space between the felt cover- ings of the case and spectrograph being about 2- 5cm. and uniform throughout. By the division of the heating coils into two sections, their uniform distribution, and the uniform space between spectrpgraph and case, the temperature throughout the case should be maintained nearly uniform and not much trouble with unequal temperature should occur. There is no question that some method of mechanical stirring of the air inside the case would give better results, but the difficulty of additional weight and complication with possible vibration prohibit its use. The temperature control so far as it has been tested works admirably. There is as before a slight drop in the temperature of the prism box when the external tempera- ture drops rapidly, but that does not last long, and by applying the control in the afternoon, thoroughly ventilating the dome so that considerable of the cooling will have taken place, the temperature remains steady for the night. Adjustment of the instrument. After the instrument was completed there were several adjustments to be made before any measurable spectra could be obtained. The first of these was to set the slit at the principal focus of the collimator lens. This was done by Schuster's method of alternate focussing of collimator and observing teles- cope on the same spectral line, the prism being placed alternately to one side and the other of the position of minimum deviation. This method gives satisfactory results, successive values agreeing within two or three-tenths of a millimetre and the mean of several being taken. The prism was easily set to minimum deviation for the lino Fe, 4325-9. This particular line was chosen on acount of the very irregular results given by the line H p in the numerous measures of ft Orionis, and the consequent determination to shift the central line towards the violet in the new instrument. The measures above referred to show that more accordant results are obtained with the lines to the violet end of the spectrum than with H p , and as resolving power, purity, and linear dispersion are all greater there, this should result in a further increase in accuracy. The camera focus is determined in precisely the same way, as with the pre- vious instrument, by making adjacent spectra through the refracting edge and base half of the prisms, and determining the focus by the continuity of the lines. A slit is cut in the side of the spectrograph box into which a semicircular diaphragm can be PLA S KETT ASTROPH YblCS. FIG. 5 New Single-Prism Spectrograph, ready for use. 25a p. 168 REPORT OF THE CHIEF ASTRONOMER 169 SESSIONAL PAPER No. 25a placed and rotated, so as to occult first one and then the other half of the light pencil. The inclination of the plate, determined of course at the same time, is about 16 -5, the same as with the first objective of this type. A very curious and at the same time very useful property of the new spectrograph is the constancy of focus of the system for different temperatures. With the two pre- vious instruments, the focal setting increased with increase of temperature about 012mm. per degree centigrade. Between the temperatures of and 20, all so far tested in the new spectrograph, the camera setting remains unchanged at 27-69 as determined by a number of careful tests. This with the absolute constancy and rigidity of the new instrument is a point of very great value in obtaining accurate results, as it obviates the necessity of testing the focus each time the instrument is used with the possibility of mistakes in the determination of the true setting. It is difficult to explain why there should be this difference, although it is probably due to the fact that the parts connecting camera objective and plate are of steel in the new instrument instead of brass, whose coefficient of expansion is greater. At any rate the combination of brass collimator tube, whose setting is un- changed, and steel camera tube gives settings for camera focus constant at all tem- peratures so far observed. If the collimator tube had been steel or the camera tube brass, there would have undoubtedly been a change in the setting with change of temperature. The New Spectrograph in practice. As stated above the instrument was only com- pleted in the beginning of March, and consequently has not been in use long enough to enable its advantages and disadvantages to be fully determined. There is, however, no question that spectra of better quality for measurement will be obtained with it than with the single-prism form of the previous instrument in which the lines were occasionally, especially with the longer exposures somewhat blurred and diffuse, due to flexure or temperature change or both. As will be seen later, flexure in the new instrument is absent, and owing to its compact form any temperature changes should have much less effect on line displacements. As a matter of fact the temperature regulation is much better with the new instrument and no spectra yet obtained, even with very long exposure, show any trace whatever of diffuseness of the lines. Again, the constancy of the camera focus is another factor tending to better results, as one is always sure of the true focus and no fear of systematic displacements due to poor focus can arise. Tests have been made similar to those of last year, on the relative freedom from accidental and systematic errors of spectra made at different slit-widths. These show, that on the whole in early type stars with this instrument more accurate values are obtained with a slit about 0-051mm. wide than with slits narrower or wider. The comparative exposures required with the new instrument at slit-width 0-051mm. and the previous single-prism instrument at slit-width 0- 038mm., which gives about the maximum accuracy obtainable with it in early type stars, shows an advantage, so far as can be at present determined, of about 25 per cent for the new instrument. To offset this, however, it must be* stated that, owing probably to the increased absorption of the larger prism, the intensity of the spectrum at the violet end is appreciably less and for equal intensity of the K line, sometimes required, most of the advantage will be lost. In the case of stars in which the extreme violet is not required, however, there is a considerable saving in time and increase in output by the use of the new instrument. This loss in the violet may be due possibly to other causes than absorp- tion of the prism, such as in the guiding or the position of the corrector and form of the colour curve, and if such is the case, and this will be shortly tested, it may to a great extent be overcome. Careful tests of the flexure of the new instrument have been carried out showing exceedingly satisfactory results. The method of testing was to attach the speetro- graph to the telescope, the latter being pointed to the meridian. If 'the telescope is 170 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 turned in declination pointing first to the south and then to the north horizon, it is evident that the spectrograph will have rotated in its own plane through 180, and there will have been induced in it the maximum possible double flexure. In these two positions spectra were made through a suitable slit diaphragm, the one used for focussing in which the adjacent spectra touch each other being the best, as any dis- placement of the line between the two exposures will at once be evident. Three sets of exposures of the comparison spark were made on the one plate, by sliding the camera back in its ways between exposures, two for flexure and one with the spectro- graph stationary for comparison. Examination of these plates showed no measurable flexure. In some of the lines a very slight displacement could just be detected under high power magnification, but this if due to flexure was quite beyond measurement. As a matter of fact, on the plate being given to Mr. Harper with the request to select from the three the spectrum in which no movement had occurred, he found it impossi- ble to determine which spectra were affected by flexure. As the flexure present during any reasonable exposure can only be a small fraction of that given by the method above described, it is quite evident that the spectra will be absolutely free from any line displacement due to flexure of the spectrograph. It may be of interest to state that flexure tests made of the instrument with the counterbalancing weights removed, and with consequently only two points of support, also showed remarkable freedom from flexure. Although the flexure was slightly more perceptible it was again quite immea- surable, showing the great stability and rigidity of the form of construction adopted. The previous single-prism spectrograph showed when first constructed a flexure of about OSSnun., equivalent to a velocity of 70km. per second. When tested at the same time as the new one it was found the flexure had increased to nearly -060mm., equivalent to over 100km. per second. As a displacement of the sharp comparison lines equivalent to a velocity of two or three kilometres would be measurable, it is at once seen how much more stable the new instrument is. It is, so far as I can learn, more stable than any other single-prism spectrograph in existence. . The new single-prism instrument, owing to its greater aperture and its design, is necessarily heavier than the three-prism spectrograph and some changes were neces- sary in the arrangement of the counterweights for balancing. As will be seen from Figs. 2 and 5, the centre of mass is considerably to the left of the optical axis, and in order to properly balance in declination, weight would have to be added to the oppo- site side of the tube near the object glass. Conseqtiently rods for carrying weights were attached to both north and south sides of the tube near the objective, and the telescope can now be easily placed in good balance whatever attachment is used. A counterweighted stand for attaching and detaching the new spectrograph, and for carrying it when not in use is provided. It is of quite similar construction to that used with the previous instrument, and allows the spectrograph to be fastened to the telescope in about a minute. With the separate relay box and set of plug contacts, both spectrographs may be maintained at constant temperature, and the change from one prism to three prisms or vice versa made in two or three minutes without disturb- ance of the temperature regulation, in either case. There will now be given the results of the tests of the new ' Single Material ' and the ' Ross Special Homocentric ' lenses, and, for completeness, the whole paper, as it will later be published in the Astrophysical Journal, will be given. CAMERA OBJECTIVES FOR SPECTROORAPHS. It is well known that the camera objectives in general use in stellar spectrographic work have a very limited field of good definition, not exceeding in general 2, which covers, in the usual dispersion of three prisms, about 200 tenth-metres. While this is a sufficient range for spectra of the second type, which are rich in lines, it is not sufficient for early-type spectra which may contain only one or two lines in this region, and in which, consequently, the errors of measurement will be high. As practically REPORT OF THE CHIEF ASTRONOMER 171 SESSIONAL PAPER No. 25a the whole photographic region of the spectrum, Hp to K, may be obtained in one ex- posure with either, refractor or reflector, it is evident that a considerable gain in the measurable material in such spectra would be obtained, without increase in exposure time, if a camera lens giving a considerably wider field were available. Various attempts at the solution of this problem have been made, of which the most successful known to me is that described by Hartmann.* This objective made by Zeiss, known as the ' Chromat,' is constructed of the same material as the prisms, and is composed of two simple meniscus elements, one positive, one negative, separated by a small air space. As there is no chromatic correction the spectra are brought into focus by inclining the plate towards the violet about 16 from the normal to the axis with a dispersion of three prisms. According to Hartmanii this objective gives a flat field of 14. A Zeiss ' Chromat ' has been in use in Ottawa for considerably over a year, entirely fulfilling expectations and giving, after slightly increasing the separation of the elements, the whole field used, from H p to H8 (about 8), almost absolutely flat with excellent definition. There can be no doubt that the field would extend farther if necessary. Unfortunately, as was learned upon inquiry from Zeiss, this type of objective cannot be successfully made of a larger angular aperture than about f!2. This was confirmed by the performance of a shorter focus lens of the same type (aperture ratio f8) constructed by Brashear which gave inferior definition. More recently, however. Hoss Limited, London, have designed and constructed especially to conform to our requirements a lens similar in form to their ' Homocentric,' consisting of four separ- ated elements, but following the principle of the ' Chromat ' in being entirely made of the prism material and consequently requiring inclination of the plate to bring the spectrum into focus. This lens, which will be more fully discussed later, gives, at an .aperture ratio of f5-6, excellent definition and a flat field. The above remarks apply to a dispersion of three prisms for which this type is especially adapted. If it were used with one prism, in addition to the limitations as to aperture, the plate in- clination required (about 50) would be inconvenient and practically inadmissible in radial velocity work. There are consequently required, short-focus objectives giving a flat field with three prisms, and objectives giving a flatter field than the regular trip- let with a single prism. This need, together with what had already been accomplished by Hartmann and Zeiss, was laid before the J. A. Brashear Co. who, with their usual willingness, put their best efforts at our disposal and, in collab- oration with Prof. Hastings, produced two eminently successful objectives. In both of these the employment of one kind of glass only is followed, although not, as in the ' Chromat,' of the same material as the prisms, and the consequent chromatic differ- ences in focus are overcome by inclining the plate. The objective first produced, to which they have given the name ' Single Material ' is composed of two widely separ- ated positive elements of crown glass of the lowest dispersion and is especially adapted for use with one prism, giving exquisite definition and a field flat within 0-lmm. over the whole visible and considerably into the ultra-violet spectrum. The other is similar to the ' Chromat ' in form but made of light crown glass, giving also a flat field and good definition with three prisms with a plate inclination of only slightly over half that of the ' Chromat.' The limiting aperture ratio of the former of these objectives is about f8, of the latter f!2, so that evidently they can not supply the need of short-focus lenses of /6 or thereabouts for either single or three-prism work. The only prospect of success in this respect seemed to lie in some of the modern anastigmat photographic lenses, and a number of different makes were accordingly obtained for trial. The definition of several of these, though good enough for ordinary Zeitschrift fiir Instrumentenkunde, September, 1904. 172 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 photographic work, would not stand the critical test of spectrum photography owing probably to some residual spherical aberration. Two, however, the Ross ' Homocentrie ' and the Zeiss l Tessar,' gave good definition and the forms of their fields were accord- ingly determined. It may not be out of place to give a brief description of the method employed in determining the fields of the ten lenses tested. The dispersion for eight of them was pro- duced by the Ottawa spectfograph, having the following optical constants: Hastings ' Isokumatic ' collimator objective of 35mm. aperture and 525mm. focus ; one or three prisms of Jena glass O. 102, angles 63 50' each; ray at minimum deviation \4415. Two of the objectives were tested with a new single-prism spectrograph having ' Isoku matic' collimator of 51mm. aperture and 763mm. focus, O. 102 prism of angle 63 30', ray at minimum A4325. The positions of focus in different parts of the field were determined by a modifi- cation of Hartmann's method* of extra-focal exposures. By means of a revolvable semi-circular diaphragm behind the collimator lens and an occulting diaphragm in front of the slit, a narrow strip of spectrum, photographed through the half of the prisms near the refracting edge, was placed between and touching two narrow strips made through the base half of the prisms. Evidently, when the plate is in the focus of the camera lens for any particular line in the spectrum, the adjacent portions of this line will be continuous, while, if not in focus, the central section will be displaced to red or violet of the outside sections, the direction and magnitude of this displace- ment giving a measure of the position of the focal point for the line in question. Two such plates, one inside and one outside the focus, will suffice to determine the Jorm of the field. In order to avoid the labour of measurement and computation and on account of the diffuseness of the lines and consequent inaccuracy of measurement, when the plate is more than a millimetre from the focus, I have generally preferred to make a number of spectra, by the method outlined above, at camera settings about 0-25mm. apart within and without the focus. Five of these have in general sufficed to determine the focal curve and, as the camera back can be moved laterally, they can all be made on one plate, thus allowing ready comparisons. Simple inspection of these spectra under a microscope or even by a hand magnifier enables the focus of any line to be determined to about 0-05mm. by observing at which of two successive spectra the central section has opposite displacements with respect to the outside sec- tions. Interpolation to the above accuracy can then generally be made. This takes only one-tenth the time and is probably equally as accurate as the method of measure- ing the displacements and computing the distance from focus. I may say that the camera setting in our regular work is always determined in this way, enabling the plate to be certainly placed considerably within 0-lmm. of the true focus. This method is probably open to the objection that it will not give the true focal point when the system has aberration, but it must be remembered that, to prevent systematic displacements in radial velocity work due to non-uniform illumination of the collimator objective, this method, which determines the focus by the absence of such displacement, is certainly the one that should be used. Moreover, in this case tests at full aperture, so far as the focus can be determined by definition, confirmed the results of the former method, and there is no reason to doubt the accuracy of the focal curves determined. * Zeitschrift fur Instrumentenkunde, 24, 1, 1904. REPORT OF THE CHIEF ASTRONOMER 173 SESSIONAL PAPER No. 25a The following ten lenses, given in the order of procuring and testing, were tested for their curvature of field. OBJECTIVES TESTED FOR FIELD. Number Objective. Aperture. Focal Length. Tested with dispersion of 1. 2. . 3 . 4 5'. '. 6 . 7. 8. . 9 . 10. Brashear Single Material 45 45 40 48 45 45 45 57 57 40 525 525 254 305 525 525 375 480 457 254 1 Prism, 3 Prisms. 3 Prisms. 3 Prisms. 3 Prisms. 3 Prisms. 3 Prisms. 3 Prisms. New I Prism, 3 Prisms. New 1 Prism. 3 Prisms. Zeiss Chroinat Ross Hoinocentric Zeiss Tessar , Brashear Light Crown it Telescope Flint .... it O. 102 ("Chromat") ii Triplet ii Single Material Ross Special Hontoctntric The form of field of each- of the lenses is given in the accompanying figures where the horizontal lines represent differences of focus of one millimetre, the wave length and angular distance from the optical axis are shown by the vertical lines, and the diameters of the circles representing the observed points are 0-2m.m. Wherever the curves are not horizontal indicates that the inclination of the plate holder required changing slightly, but this of course has no effect on the form of the field. In order to group the curves according to the type and purpose of the objectives, the order given in the above table has been changed and those of longer focus used with a dis- persion of three prisms will be first considered (Fig. 6). Brashear Single Material (No. 1.) This consists of two simple converging lenses, the front double convex, the rear convex meniscus, of crown glass of lowest index, separated by nearly one-third the focal length. As will be seen later, this objective gives a beautiful field with one prism, but is strongly concave towards the lens with three prisms, with about the same cur- vature of field as the regular Hastings Triplet. The inclination of the plate towards the violet is slightly over 5. Allowing deviation from focus of 0-lmm., slightly over 2 of field is usable. Zeiss Chromat (No. 2). This consists of two strongly curved meniscus elements of Jena glass O. 102, the front diverging, the rear converging and of about half the focus of the combination. When received it gave a field convex towards the lens as shown in the upper curve. When the separation between the elements was increased from 2-25 to 4- 5mm. .the field became almost absolutely flat over the whole 8, giving at the same time excellent definition. Inclination of the plate towards the violet about 16. Brashear Light Crown (No. 5). This is a lens of the same form as the ' Chromat ' except that it is made of light crown glass. With the original separation the field was concave but became flat on decreasing the separation from 4-8 to 3 -2mm. This change in separation resulted in loss of defining power. The objective was re-figured at the new separation and gave good definition and field flat over practically the whole range. Inclination of plate to- the violet about 9. 174 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 Brashear Telescope Flint (No, 6). An objective similar to the previous one only made of telescope flint glass. The field was originally convex but became flat on increasing the separation from 4-8 to 7 -9mm. Refiguring did not give so much improvement as in the light crown objective. Field is now practically flat. Inclination of plate to the violet is about 13-5. Brashear Triplet (Hastings) (No. 8). This is a lens of the same type as used in the Mills, Bruce and Lowell spectro- graphs. The field is, as shown, strongly concave towards the objective with a usable portion, allowing deviation of 0-lmm., of about 2-5. The definition at the centre of the field is about the same as in the ' Chromat/ but towards the margins even when in focus is much inferior. All the above objectives are of relatively long focus, small angular aperture, about f 12, tested with dispersion of three prisms. Let us now examine the fields given by shorter focus objectives, using the same dispersion (Fig. 7). Boss Homocentric (No. 3). This standard photographic objective gives good definition but a strongly concave field. An increase in separation from 59 to 124mm. appears to flatten the field, but at the expense of defining power and the lens is not usable at the increased separation. Useful field is not more than 2. Zeiss Tessar (No. 4)- This objective was one of the standard form taken from the stock of Bausch and Lomb. It gives good definition and a field very slightly convex. This convexity is removed by an increase in separation from 41-0 to 41 -7mm., but with a slight loss in defining power, so that it is probably preferable to use it at the normal separation. Another lens of the same series, aperture, and focus was tested, giving practically the same field but considerably poorer definition. This is of interest as showing the differ- ences between the performance of two objectives presumably identical and indicates the desirability of specially selecting and testing the lens to be used from a number. Brashear 0. 102 ('Chromat') (No. 7). This objective of the same type and material as the Zeiss Chromat but of larger angular aperture, gives a field nearly flat with a separation of 6-3mm., but with poor definition even after refiguring. This shows that this type can not be success!' ully constructed of larger aperture ratio than fll, say. Inclination of the plate to the violet about 16. Ross Special Homocentric (No. 10). This objective was, by the kindness of the makers, Messrs. Ross, Limited, espe- cially computed and constructed for us. It has an aperture ratio of f5-6, is of prac- tically the same form as their Homocentric, but with all four elements of O. 102 glass. It gives beautiful definition and a field nearly flat, usable over 8. Change of separa- tion is -without appreciable effect on the form of field. Inclination of plate lo the violet about 16. Two types of objectives of medium and long focus have been tested with a dis- persion of one prism (Fig. 8). 1" Zeiss Chromat Brashear Triplet PLASKETT ASTROPHYSICS. 2 3 4 I Separation 4.8 mm. 3.2 3.2Refigured 4.8 mm. 7.9 7.9Refigured 2.25mm. 4.5 4600 4415 H 4200 FIG. 6 Long Focus Objectives with three prisms. Ross Homocentric Zeiss Tessar Brashear O. 102 ("Chromat") Ross Special Homocentric J I PLASKETT ASTROPHYSICS. 1 2 3 4 - 9- o e- -e e e- I i Separation 59 mm. 124 41.0 41.7 6.3 6 '3 refigured 4600 4415 H 4200 H FIG. 7 Short Focus Objectives with three prisms. ~ co *"^ (O .= o .S d "3 a,.- 12 25a p. 174 RKPORT OF Till: CHIEF ASTRONOMER 175 SESSIONAL PAPER No. 25a Brashear Singfe Material (Nos. 1 and 9). Both of these objectives, whose form was described above, are of the same type, ~No. 1 of an aperture ratio fll-5; No. 9, f8. When used with three prisms they give the strongly concave field shown in Fig. 6, but with a single prism the field is almost absolutely flat over the whole range of visible and as far into the ultra-violet spectrum as the prism will transmit. The definition given is excellent and the objectives leave nothing to be desired for single-prism work. The inclination of plate to the violet is about 16. I am glad to express here my appreciation of the efforts, as well as my admiration for the skill of Mr. McDowell in figuring these objectives. As both com- ponents are converging, the only means of removing the positive spherical aberration is by departure from spherical surfaces. While, as Mr. McDowell says, this was com- paratively easy for No. 1, of the smaller angular aperture, it taxed even his skill to remove it entirely in the other, and it was only after a second trial and the use of a special device that the objective was finally made perfect. Brashear Triplet (No. 8). This, as with three prisms, gives a field concave towards the objective but with considerably less curvature. The usable field is somewhat over 2. Definition good. The final resiilts of the investigation may be summarized as follows: For a dispersion of three prisms with a camera of fairly long focus two objectives are much superior to the others, the Zeiss ' Chromat ' and the Brashear Light Crown. The former gives a flatter field and slightly better definition than the latter, but on the other hand the smaller plate inclination of 8 instead of 16 and the smaller absorption of the Brashear are an advantage. The definition of either of these is fully equal to the regular triplet in the centre of the field and much superior at the margins. For short-focus lenses with three prisms both the Zeiss ' Tessar ' and the Ross ' Special Homocentric ' give good definition and flat fields. The Ross can be used of shorter focus than the Tessar, and gives exquisite definition, but the field of the Tessar is flatter and the plate is normal to the axis. In single-prism work the Brashear ' Single Material ' is much superior to the type .of Triplet usually employed, both in definition and extent of field and can not be surpassed or even equalled for its purpose. MEASUREMENT AXD REDUCTION OF STELLAR SPECTRA. With the exception of some plates measured on the spectro-comparator, which will be fully described below, all of the measurements have been made with the Toepfer microscope, and reduced by the modified Hartmann method previously described and explained. When the new single-prism spectrograph was brought into use it was found necessary to obtain tables, similar to those previously prepared, for the reduc- tion of the spectrograms. As before, plates of the comparison spectrum were made at three temperatures, as far separated as the time and season would permit, and these plates were measured. c From these measures the constants of the Hartmann interpolation formula ).-)(, = s ~ f s were computed, losing as the three standards different sets of lines, for the purpose of determining which would give the best agreement over the whole range of spectrum. It was not thought necessary, after the work of Mr. McLean, described in the 1907 report, to use the complete formula, (A -4,)"' as he showed that with the previous single-prism instruments, the best agreement was given when a = 1. 25a 14 176 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 It was found that standards chosen at the middle and near the ends of the spec- trum gave the best agreement on the whole and these, with the measures corresponding and the constants for the three temperatures, are given. TABLE OF CONSTANTS. 4864-943 4311-162 3930-450 Temp. C. _____ *0 logc A. *i S-2 3 2-8.. 75-9840 50-9383 20-5074 176-9410 5-4249320 2229 -851 8-6.. 75-9851 50-9168 20-4543 176-9951 5-4250393 2230 595 15-6.. 75-9557 50-8696 .20-3763 176-9751 5-4248560 2231-943 Forming the differences between the s' a and the log. of the ratio we have : Temp. s i * C. $i S t ^2 "~^3 *i 3 *i *s 2-8... 25 0457 30-4309 55-4766 9 '65462 8-6 25-0683 30 4625 55 '5308 9 65459 15-6 25-0861 30 4933 55-5794 9-65452 The changes in these differences and in the log. of the ratio are only about half those given with the other single-prism spectrograph. This is undoubtedly due to the fact that the camera setting remains unchanged with change of temperature in the new instrument, and, consequently, only the change in the angular dispersion appears, instead of that due to angular dispersion plus that due to increase in distance of the focal plane from the camera objective. Averaging up the differences as far as possible, an increase of temperature of 1C. o o increases s. - s t by -008 revolution, and diminishes log. -by-00001. ! - s Forming an arbitrary series with these differences from the last two columns of the previous table, keeping them as close as possible to the observed values and com- puting 2nd and 3rd columns we have for differences of 10. Temp. C. .,-., -, ,-.; log r -10... 25-0070 30-3675 55-3745 9-65475 0. 25-0376 SO'4169 55-4545 9-65465 + 10. 25 0681 30*4664 55-5345 9-65455 +20. 25"0985 30 "5160 55-6145 9-65445 Again, taking the arbitrary equidistant values of s. 2 for these four temperatures, which make the micrometer reading for the iron line at minimum deviation X4325-9 Temp. C. i S 2 s s o logo \ -10.. 75-9260 50'9190 20-5515 75-9516 50-9200 20-5031 176 '91 29 5 ' 4250327 2229 ' 197" + 10 75-9891 50-9210 20"4546 176'9736 5 ' 4248342 2231 ' 163 + 20 76'0205 50'9220 20'4060 177 ' 0327 5 ' 4246277 2233 ' 137" REPORT OF THE CHIEF ASTRONOMER ~~" 177 SESSIONAL PAPER No. 25a as near as possible to 50-0000, we obtain the "following values for s, s 2 s 3 and from them the three constants of the formula: From these constants were computed the micrometer readings for all the star and comparison lines employed, and in addition the velocities corresponding to one revolution of the micrometer screw for each star line. This latter is obtained by dif- ferentiating the dispersion formula and applying Doppler's principle resulting in 299860 (X - ;L) 2 ^ c The velocities per revolution, as compared with those for the original single prism, are given for a few lines below to give some indication of the difference in dispersion. Velocities per Revolution. Temperature + 10 C. Wave Length. Old One Prism. New One Prism. 4861-527 1454-4 1604-5 4713-308 1336-6 1473-7 4549-766 1209-0 1332-1 4481-400 1156-5 1273-9 4395-286 1091-1 1201-3 4340-634 1050-1 1155-8 4260-640 990-6 1089-9 4202-161 947-7 1042-3 4143-928 905-4 995-4 4101-890 875-2 961-9 4026-352 821-5 902-4 3970-177 728-1 858-3 3933-825 756-0 830-9 These velocities show that the new instrument has very approximately ten per sent less linear dispersion than the old. This, of course, is due almost entirely to the shorter focus camera lens used, as the prisms are nearly alike and the angular dis- persion similar. The Spectro-comparator. The Spectro-comparator, which was briefly referred to in my last report, has not >een used except on a few plates of Geminorum more to test the capabilities of the nstrument than for the purpose of obtaining definite measures of the velocity of this star. Before giving these measures, however, it may be well to shortly describe the instrument, its principle and the methods of measurement These have been very fully lescribed by its inventor, Dr. Hartmann, in the publications of the Astrophysical Dbservatory of Potsdam, Volume XVIIL, Part 1, and consequently need not be gone into in great detail here. The principle of measurement depends upon the direct comparison in a special form of double image microscope of the star spectrum, whose velocity is required with a standard spectrum of the sun, whose velocity at the instant the spectrum was made, 25a 14J L78 DEPARTMENT OF TEE INTERIOR 9-10 EDWARD VII., A. 1910 can be readily computed. The difference in the displacements of the star and the sun Lines with respect to the same metallic comparison lines on each plate is measured by a micrometer screw, and this linear displacement can be at once converted into kilo- metres by multiplication by a known or easily computed constant. By adding to this radial velocity that of the sun with respect to the earth, with the proper sign, we obtain the velocity of the star with respect to the earth, and this can be readily reduced to the sun in the well known way. The instrument of which a photograph is shown in Fig. 9 and diagrams in Figs. 10 and 11 was constructed by Zeiss in a very workmanlike manner. It con- sists essentially of a table T, Fig. 10, which carries at E t and E 2 the standard solar and the star spectrum respectively, and of a single ocular double objective microscope carried above the table on the bracket R f Fig. 11, which combines and compares the images of the two spectra. The table T, which as Fig. 11 shows, is inclined at 45 to the horizontal for con- venience in measuring, slides at its lower portion on the steel cylinder Z 35mm. dia- meter and at its upper part on the steel bar J. It is moved on these bearings over a range of 12cm. by rack and pinion of which the knurled wheel is shown at K and is clamped in any position, read off on the scale and vernier N, by the clamp screw near K. At the upper part of the table a carriage B 2 slides transversely in ways, adjust- ment being made by the screw G, while a secondary carriage A 2 , having a slit 1cm. wide and 12cm. long, through which the star spectrum is illuminated by the plane mirror shown in Fig. 11 is oriented by the tangent screw D s and the opposing spring F., so that the spectrum, clamped on it may be placed parallel to the motion of the table T. The carriage B lt which carries the standard or fundamental solar spectrum, has an orienting table A lf adjusted by the screw D 1 and spring F lf and slides in ways parallel to the motion of the table T. It is moved by means of the micrometer screw 8 of 0-5mm. pitch, having a range of movement slightly over 2cm. The head is divided into 100 parts so that the movement of the sun spectrum can be read direct to 0-005mm. and estimated to 0-0005mm. The double microscope, Fig. 11, by which these two spectra are observed is sup- ported by the bracket R on which the arm R 1 slides, moved by the screw //, the position being read on the scale W. The tubes carrying the objectives 1 O x are attached at a tixed distance from one another to a plate L, movable in ways on the arm R^ by the screw Q. At the upper ends of the objective tubes, which are provided with rack and pinion movement for focussing, ai-e the prisms P, P 2 , which reflect the light from the spectra on E l and E 2 to the compound prism P, P t . On the hypothenuse of the prism P, is a surface silvered in the form shown in Fig. 12, and the two prisms are then Fig. 12. "indented together with Canada Balsam. The proper proportioning of the widths of the silver strips enables one to see, on looking through the eyepiece, a narrow strip of a -ji 25a-p. 178 PLASKETT ASTROPHYSICS. FIG. 10. FIG. 11. REPORT 01'' THE CHIEF ASTRONOMER 179 SESSIONAL PAPER No. 25a star spectrum between and touching two strips of sim spectrum, and also on either side a narrow strip of the star comparison between and touching strips of sun comparison . spectrum. The compound prism P 3 P t , with the eyepiece, is carried on a slide Z/movec by rack and pinion V, so that the distance between the eyepiece and the objectives and consequently the magnification of the two spectra may be changed at will. This is to enable them, even though of different dispersions, to be made apparently identi- cal in the field and hence readily and accurately comparable. The adjustment of the spectra on the machine is a comparatively simple matter, only taking a few moments. The standard or fundamental solar spectrum usually made on a lantern or process plate in order to obtain sufficient contrast, is placed on its carriage, and clamped by a pair of spring microscope clamps. The carriage is then moved by the pinion K until the centre of rotation of the orienting arrangement is directly under the microscope 1, which is in this case at the reading 132-3 on the scale ~Y. The whole microscope system is now moved by the screw Q until the solar spec- trum is centrally situated with respect to the central silver strip in the field. By moving the carriage back and forwards the spectrum can be rapidly oriented. The star spectrum may be similarly oriented while it is made central by the screw G. There then remains only to adjust the magnification of the separate spectra, the com- parison lines of the two appear coincident in the whole extent of the field of view. By moving the ocular by the rack and pinion V, the magnification of one spectrum is increased and of the other decreased. This will evidently disturb the focus, but this can be easily corrected by adjusting the objectives 0^ and 2 by their focussing screws seen in Fig. 9. This will again slightly change the magnification and the process may need to be repeated, but a little practice soon enables one to equalize the apparent dis- persion very quickly. Before making any measurements it is necessary to divide the fundamental solar spectrum into regions, indicated by small ink dots, and numbered for identification. These regions are so chosen that there is a slight overlapping of the field in adjacent regions with the magnification to be employed. The dots, which are brought under the wire in the measurement, are placed, as nearly as possible, in the centre of a group of good solar lines and at the same time so that the field includes a number of good comparison lines. The regions selected in a series of good fundamental solar spectra made on May 14, 1908, on Seed process plates are given in the following table. In addition in the third column of the table are given the velocities corresponding to one revolution of the micrometer screw. These velocities were computed from the mea- surement of lines on the fundamental spectrum by the micrometer screw of the com- parator. These linear measurements were used to obtain the constants of the Hart- mann formula, and from these constants the velocities corresponding to the wave length of each region were computed. 180 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 CONSTANTS OF FUNDAMENTAL SPECTRA, 1519-1526. Exposed May 14, 1908. No. of Region. Wave Length. Vel. per Rev. S. No. of Region. Wave Length. Vel. per Rev. S. 1 4867-0 582-1 14... 4374 ' 5 364 '2 2 4807'0 555-4 15 4346 '5 352'1 3 4754-0 531-9 16 4322 '8 341'8 4 4709-6 512-0 17.... 4298-2 331 1 5 4669-0 494-0 18 4273'3 320'4 6 4628 '7 476-0 19 4249'9 310'4 7 4590-2 459-1 20 4226'S 300'6 8 4554 6 443-2 21 4206-0 291'7 9 4523-9 429-7 22 4184'3 282'1 10 4492 415'7 23 4157 ' 2 271'2 11 4460-3 401-7 24 4139-5 263 '4 12 4429-6 388'3 25. 4117 '8 255-7 13 4402-1 376-2 26 4099'0 246 '7 Region. 3 4 5 6 7 13... 1-37646 1 ' 42045 1 ' 47137 14 . 1'32312 1'36175 1 ' 40594 15 1-24332 1'27409 1'30846 1' 34727 16 1-17577 1-20095 1 ' 22877 1 ' 25961 1'29412 17 1-13813 1-16116 1-18647 1 ' 21436 1 ' 24533 18 1-10239 1-12355 1-14671 1 ' 17207 1 ' 20008 19 1-06833 1-08786 1'10914 1 ' 13236 1" 157 84 20 1-03576 1-05385 1-07349 1'09483 1" 11815 21 1-00457 1-02139 1'03958 1'05928 1 ' 08072 22 D'97452 0-99028 1'00710 1'02535 1 ' 04514 23 G'94533 G'95996 24 0-91718 G'93098 25 0-88998 0-90283 26 G'86348 0-87555 The magnification of the two spectra may be varied between about 10 and 40 fold by means of two pairs of objectives and three oculars. Moreover, by suitably varying these the silver strips on the prism may be varied in apparent width to suit star spectra of different widths. It has been found that a magnification of about 20 seems to give better and easier measurements than either higher or lower powers, and it has gener- ally been used, although tests have been made with different powers. When the plates have been adjusted as described above, the line in the centre of, the field is set on the dot towards the red end at which it is deemed advisable the mea- surement should begin. This is determined by the appearance of the star spectrum and of its comparison lines. It has not been generally taken lower down than No. 5, at wave length A.4669, as below that the comparison spectrum is not so good and no gain in accuracy would result. Towards the violet end the measurement is carried until the star spectrum becomes too weak for accurate comparisons, frequently about dot 20, wave length A.4227. However, in a well exposed star spectrum the measure- ment could be extended over the whole range on the plate from Hp to H8, although in my opinion nothing would be gained in accuracy by such procedure over that obtained by the use of a less number, say 12 or 15 regions. The measurement pro- ceeds according to a regular scheme of alternation of star and comparison settings, REPORT OF THE CHIEF ASTRONOMER 181 SESSIONAL PAPER No. 25a so that at each region there are two settings on the star and two on the comparison lines, one by forward and one by backward rotation of the screw in each case. As soon as the measurement is completed, both star and fundamental spectra are reversed on the machine to overcome personality in the settings and the same regions are again measured. It has been my experience that the most difficult part of the measurement is the determination of the point of coincidence of star and fundamental spectrum. Although with solar type stars of a considerable range in type, there is so little difference in the lines as to cause no trouble, nevertheless there are frequently apparently accidental irregularities in some of the lines in a region which render it difficult to determine the exact point of coincidence. The field extends over a considerable angle, and the eye can only observe at the most two or three lines at a time. These may be brought into the best coincidence, while lines in another part of the field may be better suited by a slightly different setting, and the best average is sometimes troublesome to obtain. These irregularities are chiefly due, I think, to irregular deposition of the silver grains fin the comparatively coarse structure of the fast plates, to local distortions of the photographic film, to possibly non-uniform intensity of the star spectrum throughout its width and to other causes of a similar nature rather than to constant differences in the spectrum of star and sun. Such differences can be noted in the case of some lines, but these seem to be few compared with the accidental deviations observed. This difficulty does not exist to so great an extent with regard to the emission lines. Pro- vided the comparison spectra are of nearly the same intensity, coincidences can be easily, quickly, and accurately obtained. The accidental deviations observed in the apparent positions of star lines serve to explain the comparatively high residual some- times obtained in the direct measurement of good lines in solar type spectra. After the measurement is completed the reduction of the separate measures to velocities is a simple matter. The difference in the settings for coincidence between emission and absorption spectra, multiplied by the velocity per revolution at the region under consideration gives the velocity at once. These differences are, however, tabu- lated for both positions of the plate, and the mean of the two for each region multi- plied by the velocity factor gives the velocity for the region, while the velocity for the plate is obtained from the mean of the regions. This considers all the regions as of equal weight, whereas such is not the case. In some parts of the spectrum the lines are more numerous or of better quality, and moreover as the dispersion increases, as we go towards the violet, greater weight should be given. There are then two courses open, to give weights according to the quality of the regions, increasing these as we go towards the violet, or to give weights propor- tional to the ^dispersion. The latter method is much simpler, and should give prac- tically the same values as the more complex method and better values than the simple mean. Moreover, Hartmann has developed a very simple method of obtaining the velocity from the differences. If we call the differences with red to right d^ and with red to left d 2 , then the mean d = I (d^ + d 2 ), which multiplied by the velocity factor s, gives velocity sd for the region. Its weight is proportional to- , and hence the weighted mean velocity can be very simply represented by j~ As a = | (a t + a,) we 27 can avoid taking the means of the differences by changing it to 7 - . If we take 2 2 s the velocity values per revolution of the fundamental spectrum and form the expres- sions log ( " T | between all the regions which are likely to be used, the only pro- 182 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 cedure necessary to obtain the weighted mean velocity is to add all the differences together and add to the logarithm of the sum the tabulated value of the above expres- sion. To the velocity of which this sum is the logarithm, must be added the computed radial velocity of the sum when the spectrum was made, and we have the radial velocity of the star with respect to the earth, which reduced for diurnal and annual motion will give us the velocity with respect to the sun. As mentioned previously, onty a few plates of ft Geminorum made with the three- prism spectrograph have been measured, principally as a test of the capabilities of the instrument. It can practically be used only with spectra of the second and third classes, those with numerous well defined lines, allied to the spectrum of the sun. Our single-prism spectrograph has been almost entirely employed on stars of early type spectra, which can not be economically or accurately measured with the spectro- comparator. However, work on some solar type spectroscopic binaries with a short- focus camera on the three-prism spectrograph is about to start, and for the measure- ment of such spectra the comparator is especially suited. One spectrum of /3 Geminorum No. 1373, of only moderately good quality, was- selected as a test plate and has been measured fifteen times with different fundamental spectra, different arrangements of objectives and oculars and with two different ocular prisms. The measures and their summary given below enable an estimate of the accuracy obtainable in measurement to be formed. Further ten additional plates of ft Gem- inorum have been measured with constant conditions in the comparator, which enables an estimate to be formed of the instrumental errors to be expected in the making of the spectra. These also with a summary are given below: REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a j8 GEMINORUM 1373. SOI,AU STANDARD 1360. 183 Observer Measurer / Region. * d t d V u 7 053 049 052 24-84 -0-06 8 47 48 48 22-18 + 2-60 9 53 54 53 24 01 + 0-77 10 55 51 53 23-53 + 1-25 11 (50 51 55 23-87 + 0-91 12 50 48 49 20-58 + 4-20 13 64 57 61 25-07 -0-29 14 65 65 65 26 32 -1-54 15 64 60 62 24-68 + 10 16 64 62 63 24-57 + 0-21 17 67 66 66 25-34 -0-56 18 72 73 73 27 45 -2 67 19 78 69 73 27-01 -2'23 20 79 74 76 27-51 -2-73 21 70 73 72 25 56 -0-78 22 74 73 73 25-33 -0-55 23 71 68 70 23-94 + 0-84 24 76 71 73 24-38 + 40 25 71 75 73 23 80 + 0-98 26 87 78 82 25-91 -1-13 27 84 76 80 24-48 + 0-30 28 85 90 88 26-40 + 1-62 29 91 91 91 26-57 + 1 79 30 87 71 79 22-51 + 2-26 31 89 90 89 24 03 + 0'75 1758 1683 Mean +24-78 ?d =3441 Vs-Vo = Vo = Va = Vd = 24-85 0-21 21-97 0-16 \OK = -53668 log/ = -85865 log(Vs-Vo) = 1-39533 V = + 2'93 r= +1-10 184 DEPARTMENT OF THE INTERIOR /3 GEMINORUM 1373. SOLAR STANDARD 1461. 9-10 EDWARD VII., A. 1910 Observer 1 r j -p Measurer r~ ' r> Region. rf, *2 d V V 1 049 051 050 24-90 -0-32 2 49 51 50 24 21 + 37 3 48 47 48 22-61 + 1-97 4 48 51 49 22-56 + 2-02 5 50 55 53 23-84 + 0-74 6 54 51 52 22-85 + 1-73 7 52 53 53 22-76 + 1-82 8 57 57 57 23 88 + 0'70 9 59 63 61 24-99 -0-41 10 64 62 63 25-21 -0-62 11 66 65 65 25-43 -0-85 12 68 65 66 25-25 -0-67 13 70 67 69 25-87 -1-29 14 73 70 71 26-04 - 1-46 15 64 70 67 24-05 + 0-53 16 68 73 71 24-94 -0-36 17 72 72 72 24-80 -0 22 18 74 72 73 24-60 -0-02 19 75 74 74 24-43 + 0-15 20 76 82 79 25'55 -0-97 21 82 80 81 25-62 -1-04 22 78 80 79 24-47 +0-11 23 85 84 84 25 -4S -0-90 24 78 87 83 24-68 -o-io 25 93 82 88 25-55 -0-97 1652 1658 .Mean. -f-24'58 = 3310 -V-Vo= + 24-63 Vo= + 0-52 Va= - 21-97 Vd= - 0-16 log log/ log (Vs-Vo) 51983 '87155 1-39138 r = 0-71 - V = + 3-02 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a |8 GEMINORUM 1373. 4 SOLAK STANDARD 1461. 185 Observer \ T Measurer J Jl Region . d t d, d F n 3 055 051 053 24 96 1-06 4 45 52 . 48 22-10 + 1-80 5 47 53 50 22 4 Measurer J ' b ' V ' Region. d, d 2 d V V 4 049 049 049 22 56 ^-2-12 5 52 51 51 22-94 + 1-44 6 53 54 54 23.73 + 0-65 9 60 r>7 58 24-91 -0-53 8 53 52 .53 22 21 4-2-16 9 64 57 60 24 58 -0-20 10 65 61 63 25-21 -0-83 11 67 C4 66 25-82 -1-44 12 63 67 65 24-87 -0-49 13 68 69 68 25-50 -1-12 14 73 70 72 26 41 -2 03 15 67 64 65 23-34 4-1-04 16 67 67 67 23 54 -1-0-84 17 68 73 71 24-47 -0-09 18 73 71 72 24-26 -0-12 19 69 70 69 22-78 -^1 60 20 76 74 75 24-26 4-0-12 21 83 83 83 26-25 -1-87 22 78 84 81 25-09 -0-71 23 79 79 79 23-96 ^0 42 24 81 82 81 24-08 ^-0-30 25 89 87 88 25-59 -1-21 1497 1485 Mean. . . .4-24-38 V*-Vo = 4- Vo = 4- V = - Vd = - 24-44 0-54 21-07 0-16 log = -47451 = -91356 8-Vo) = 1-38807 V = 4- 2-85 r = -f- 81 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a |3 GEMINORUM 1373. SOLAR STAM>AKO 1462. 187 Observer I T Measurer r- 2d = 3318 V-Vo = + 24-68 Vo = + 0-48 Va = - 21-07 Y,i. = - o-ir, log log/ log (V*-Vo) 52088 87155 1-39243 = o-; Region. *, *, d F n 1 052 051 051 25-40 -0-72 2 48 49 49 23-72 + 0-96 3 55 50 52 24-50 + 0-18 4 47 47 47 21-64 + 3-04 5 50 54 52 23-39 + 1-29 i> 52 51 52 22-85 + 1-83 7 60 54 57 24-48 + 0-20 8 58 57 57 23-88 + 0-80 61 62 62 25-40 -0-72 10 65 62 63 25-21 -0-53 11 64 61 63 24-65 + 0-03 12 73 70 71 27-16 -2-48 13 74 66 70 26-25 -1 57 14 67 69 68 24 94 -0-26 15 65 67 66 23-69 + 0-99 16 72 67 70 24-58 +0-10 17 70 69 69 23-77 + 0-93 18 - 72 72 72 24 '26 40-42 19 74 74 74 24-43 + 0-25 20 78 76 77 24-90 -0-22 21 84 79 81 25-62 -0-94 22 82 82 82 25-40 -0-72 23 83 79 81 24-57 +0-11 24 82 81 82 24-38 + 0-30 25 94 87 90 26-13 -1-45 1682 1636 Mean + 24-68 V = + 3 03 188 DEPARTMENT OF THE INTERIOR GEMINORUM 1373. SOLAR STANDARD 1462. 9-10 EDWARD VII., A. 1910 Observer | j g p Measurer ) ' * ' Region. rf, *, d V D 3 053 049 051 24-03 + 0-73 4 46 51 49 22-56 + 2-20 5 55 52 53 23-84 + 0-92 6 56 54 55 24-17 -fO-59 7 47 55 51 21-90 + 2-86 8 54 60 57 23-K8 +0-88 62 61 61 24-99 -0-23 10 58 67 63 25 21 -0-45 11 59 68 63 24 65 ^0-11 12 69 68 69 26 40 -1 64 13 72 67 69 25-87 -1-11 14 68 K5 67 24-58 + 0-18 15 70 64 67 24-05 4-0-71 16 72 71 72 25-2U -0-53 17 72 74 73 25-15 -0-39 18 72 71 72 24 26 + 0-50 19 78 77 77 23-42 -0-66 20 80 82 81 28 19 -1-43 21 85 80 82 25-94 -1-18 22 83 81 82 25-40 -0 64 23 88 85 86 2(5-08 -1-32 24 89 91 90 26-76 -2-00 25 89 84 85 25-26 -0-50 1577 1577 Mean f24'76 Vs-Vo = Vo = Va= Vd= = 3154 + 24-98 + 0-33 - 21-K7 - 0-16 log = -49886 log/= -89871 log (Vs-Vo) = 1-39757 V = + 3-18 = 0-79 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a ft GEMINORUM 1373. SOLAR STANDARD 1462. 189 Observer \ T c T> Measurer J J - & * r ' Region. <*? d, d F V 1 049 047 048 23-91 + 0-27 2 41 51 48 23-24 + 94 3 50 51 50 23-55 +0-63 4 50 45 48 22 10 + 2-08 5 53 51 52 23-39 + '79 8 54 56 55 24-17 + 01 7 QQ 59 60 25-76 -1-58 8 5fi 58 57 23-88 + 30 y 57 59 58 23-76 + '42 10 5<> 60 60 24-01 + -17 11 59 64 61 23-86 + -32 12 6' 66 63 24-10 + 08 13 65 server 1 r c p Low Power Ocular. Measurer / Region. *, -(I.' -2-31 14 73 64 09 2531 -1-00 15 69 65 67 24-05 -f-0'26 16 71 66 68 23-88 +0-4:-; 17 66 69 68 23-43 +0-88 18 72 70 71 28-93 + 0-38 19 73 66 70 23-11 + 1-20 20 75 77 76 24*68 -0-27 21 81 73 77 24-35 + 0-04 22 87 74 80 24-78 -0-47 23 80 73 77 23-35 + 0-9(1 24 86 83 84 24-97 -0-66 25 97 85 91 38-42 2 11 1575 1495 Mean. . ....+24-31 = 3070 Vo= + 24-32 Vo= + 33 Va= - 21 97 Vd= - 0-16 log = -48714 log /= -89871 log (\V- Vo)= 1-38585 r= + 74 V-= 2-52 Ifl-II'ORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a P GEMINORUM 1373. SOLAR STANDARD 1465. 191 Observer. I T Measurer. J J> Region. ' , d. d V V 3 051 055 053 24-96 -0-90 4 48 50 49 22-56 + 1-50 5 47 45 46 20-69 + 3-37 6 48 51 49 21-53 + 2-53 7 51 57 54 23-19 +0-87 8 51 48 50 20-95 + 3-11 g 61 64 62 25-40 -1-34 10 63 57 60 24-01 +0-05 11 66 65 66 25-82 -1-76 12 68 67 67 25-63 -T57 13 67 63 65 24-37 -0-31 14 71 63 67 24-58 - 0'52 15 72 65 69 24-77 - 0'71 16 65 66 65 22-83 + 1-23 17 72 68 70 24-12 -0-06 18 69 70 70 23-59 + 0-47 19 72 70 71 23-43 + 0-63 20 75 75 75 24-25 -0-19 21 82 76 79 24-99 -0-93 22 83 82 82 25-39 -1-33 23 85 77 81 24-57 -0-51 24 89 84 87 25-87 -1-81 25 88 90 89 25-84 -1-78 1544 1508 Mean + 24'06 Srf = 3052 Vs-Vo Vo Va Vd 24-17 0-27 21 97 0-K) log = "48458 log/ = 89871 log(Vs-Vo) = 1-38329 V = + 2-31 r= + 1-02 192 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 ft GEMINORUM 1373. SOLAR t TANDARD 14fi8. Observer Measurer / T c T> J< b ' * Region. <*i d a d V i/ 3 054 056 055' 25-91 -1-74 4 50 54 52 23-94 + 0-23 5 49 50 50 22 94 + 1 68 6 53 51 52 22-85 + 1-32 7 55 56 55 23 62 +0-55 8 57 48 53 22-21 -1-1-96 9 57 61 59 24-17 o-oo 10 65 66 65 2 Measurer. / J - b> " Region. d, d. rf F V 3 023 020 021 9'89 +0-47 4 22 22 22 10-13 + 0-23 5 19 18 19 8'55 + 1-83 6 24 21 23 10-11 +0-25 7 28 25 26 11-16 -0-80 8 25 23 24 10-06 -fO'30 9 26 28 27 11-06 -0'70 10 22 24 23 9 20 + 1-16 11 32 26 ?9 11-34 -0-98 12 28 24 26 9-95 +0-41 13 30 21 26 9-75 + 61 14 26 30 28 10 27 + 0-09 15 30 38 34 12-21 -1 85 16 26 26 26 9-13 + 1-23 17 29 36 32 11-02 -0-66 18 27 25 26 8'76 + 1-60 19 36 24 30 9-90 + 0-46 20 38 31 35 11-32 -0-96 21 37 28 32 10-12 + 0-24 22 36 32 34 10-53 -0-17 23 41 35 38 11-53 -1-17 24 40 37 39 11-59 -1-23 25 38 36 37 10-74 -0-38 683 630 Mean. + 10-36 Sd = 1313 Vs-Vo Vo Va Vd = - = + = + 10-40 33 8-67 0-22 log = -11826 log/ = -89871 log (Vs-Vo) = 1-01697 V = + 1-84 r = + 0-63 198 DEPARTMENT OF THE INTERIOR ft GEMINORUM 1417. 9-10 EDWARD VII., A. 1910 Observer \ T T> Measurer) J ' b ' r " Region. <*, d, d V 11 3 061 058 059 27-79 + 0-80 4 65 65 65 29-93 -1-34 5 59 58 59 26-54 12-05 6 66 64 65 28-56 + 0-03 7 67 65 66 28-34 + 0-25 8 65 64 65 27-24 + 1-35 9 74 69 71 29-08 -0 49 10 73 77 75 30'01 -1-42 11 75 76 76 29-73 -1-14 12 77 76 76 29-08 0-49 13 78 75 77 28-87 -0-28 14 82 74 78 28-61 -0-02 15 78 79 78 28-00 + 0-59 16 80 76 78 27-39 H-1'20 17 79 77 78 26-87 i-1 72 18 83 84 84 28 31 + 0-28 19 85 85 85 28-06 + 0-53 20 91 87 89 28-78 -0-19 21 96 96 96 30-36 -1-77 22 96 96 96 29-73 - 1-14 23 92 94 93 28-21 + 0-38 24 94 100 97 28-84 -0 25 25 105 98 101 29-32 -0-73 1821 1793 Mean + 28-59 V*-V = Vo = Va = Vd = = 3615 + 28-63 + 0-33 - 27-36 - 0-19 log = 55811 log/= -89871 log(Va-Vo) = 1-45682 V = + 1 41 r = + 0- REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a ,3 GEMINORUM 1424. 199 Observer \ MeasUrer J Region. *' Region. *, d, d F i; 3 065 062 063 29 21 + 1-43 4 65 62 64 29-47 + 1 17 5 66 65 65 29-24 +1-40 6 65 72 69 30-32 +0-32 7 74 68 71 30-49 + 0-15 8 73 69 71 29-75 + 0-89 9 70 78 74 30-31 + 0-33 10 80 76 78 31-22 -0-58 11 79 72 76 29-73 +0 91 12 84 79 81 30 99 -0-35 13 88 87 88 33-37 -2-73 14 85 79 82 30 08 +0-56 15 88 95 91 32-67 -2-03 16 - 88 92 90 31-61 -0-97 17 93 87 90 31-00 -0-36 18 89 94 92 31-00 -0-36 19 93 89 91 30-04 + 0-60 20 87 89 88 28-78 + 1-88 21 98 98 98 31-00 -0-36 22 99 97 98 30-35 + 0-29 23 99 105 102 30-94 -0-30 24 105 106 105 31 22 -0-58 25 108 111 110 31-93 -1-29 1941 1932 Mean + 30-64 Sd = 3873 Vs-Vo = + 30-67 Vo = -r 0-33 Va = - 29-19 Vd = - 0-11 log log/ log (Vs-Vo) 58805 89871 1-48676 r = 0-74 V = + 1-70 202 DEPARTMENT ()!' THi: INTERIOR 9-10 EDWARD VII., A. 1910 GEMINORUM 1460. Observer 1 T e TJ Measurer/ J> h ' r< Region. d, d, d V V 3 065 .064 064 30-15 + 1-91 4 68 63 66 30 39 + 1-67. 5 66 70 68 30-59 + 1-47 6 66 66 66 29-00 +3-06 7 68 70 69 29 63 +2-43 8 70 71 71 29-75 + 2-31 9 76 80 78 31 95 + 0-11 10 83 82 82 32-82 -0-76 11 85 83 84 :52'86 -0-80 12 86 82 84 32 14 -0-08 13 90 83 87 32-62 -0-56 14 93 89 91 33-38 -1-32 15 94 88 92 33-03 -0-97 16 93 89 91 31 96- +0-10 17 101 97 99 34 11 -2 05 18 92 92 92 31-00 + 1-06 19 95 100 98 32 35 -0-29 20 102 105 103 33-31 -1-25 21 102 105 104 32 90 -0-84 22 102 108 105 32-52 -0-46 23 107 104 105 31-85 + 0-21 24 117 119 118 35-08 -3-02 25 113 121 117 33-96 - 1'90 2034 2031 Mean + 32'06 Zd = 4065 log = 60906 log/ = 89871 log (Vs-Vo) = 50777 Vs-Vo = + 32-19 r - 1 14 Vo = + 0-33 V = - 29 24 Vd = 0-09 V = 4 3-19 Region. <*i d-n d F V 5 053 056 055 27-17 + 3 94 6 61 63 62 29-51 + 1-60 7 71 69 70 32-14 -1-03 8 67 67 67 29-69 + 1-42 9 70 73 71 30-51 + 0-60 10 73 73 73 30-35 + 0-76 11 76 77 77 30-93 + 0-18 12 77 80 78 30-29 + 0-82 13 83 86 85 31-98 -0-87 14 89 87 88 32-41 -1-30 15 88 92 90 31-69 -0-58 Ifi 95 93 94 32-13 --1-02 17 % 97 96 31-81 -0'70 18 100 103 102 32-68 -1-57 19 104 102 103 31-97 -0-86 20 104 103 104 31-26 -0-15 21 115 108 in 32-38 - 1-27 1422 1429 Mean + 31'11 RKPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 13 GEMINORUM 1472. SOLAR STANDARD 1520. 203 Observer \ Measurer < = 2851 Vs-Vo = + 31-23 Vo = + 0-38 Va = - 29'41 Vd = - 0-21 l log (Vs- >.{- 45500 1-03958 1-49458 r= + 0-94 V = + 1-99 204 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 / GEMINORUM 1500. SOLAR STANDARD 1519. Observer ) T o TJ Measurer f' L b> P ' Region. *i d 2 d V v 5 061 064 062 30-63 + 0'20 6 66 66 66 31-42 -0-59 7 64 64 64 29-38 + 1-45 8 61 66 64 28-36 + 2-47 9 73 69 71 30-51 + 0-32 10 69 70 70 29-10 + 1-73 11 77 78 77 30-93 -o-io 12 79 . 77 78 30-29 +0 54 13 86 78 82 30-85 -0-02 14 91 89 90 32-77 -1-94 15 87 80 84 29-58 + 1-25 16 92 88 90 30-76 + 0-07 17 100 92 % 31-79 -0-96 18 98 102 100 32-04 -1-21 19 104 106 105 32-59 -1-76 20 106 103 105 31-56 -0-73 21 112 104 108 31-50 -0-67 1426 1396 Mean, , 30-83 V-Vo= VO = Va= Vd-- +30-91 + 0-41 - 29 14 - 0-15 log= -45056 lo*/= 1-03958 log(Vs Vo)= 1-49014 V = + 2-03 r= 0-81 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a (3 UEMINORUM 1502 205 Observer I T TJ Measurer I 1 *' b> *' Region. *, d, d F V 3 059 065 062 29-21 + 1-98 4 69 62 65 29-93 + 1-26 5 65 65 65 29-24 +1-95 6 64 70 67 29-44 +1-75 7 67 68 68 29-20 +1-99 8 73 71 72 30 17 + 1-02 9 82 76 79 32 36 -1-17 10 83 81 82 32-82 -1-63 11 79 80 80 31 30 -0-13 12 85 90 87 33 29 - 2-10 13 89 87 88 33-00 -1-81 14 80 86 ' 83 30-44 + 0-75 15 88 88 88 31 59 -0-40 16 90 85 88 30-91 +0-28 17 89 91 90 31-02 +0-17 18 89 91 90 30 33 +0'86 19 99 100 99 32-68 -1-49 20 100 100 100 32 34 -1-15 21 98 100 99 31-31 -0-12 22 108 102 105 32-32 -1-13 23 101 93 97 29-42 +1-77 24 108 114 111 33 00 -1-81 25 110 113 111 32-22 -1 03 1975 1978 Mean +31'19 = 3953 Vs-Vo .-= + 31 31 Vo = + 0-33 Va = - 29-09 Vd = - 0-12 log = '59693 log/= '89871 log (Vs-Vo) = 1-49564 V = + 2-43 r = +0-93 206 hi:r.\l!T.\LE\'T OF THE INTERIOR 9-10 EDWARD VII., A. 1910 a GEMINOKUM 1.V27. SOLAR STANDARD 1520. Observer X y p Measurer / ' ' Region. i *. d F " 5 047 053 050 24-70 + 2-16 6 51 52 52 24 75 + 2-11 7 55 58 56 25-71 + 1-15 8 62 61 62 27-48 -0-62 9 58 64 61 2621 -fO'65 10 60 64 62 25-77 + 1-09 11 69 65 07 26-91 -0-05 12 66 72 69 26-79 ^0-07 13 74 73 73 27-46 - 0-60 14 75 79 77 28 04 -1-18 15 83 74 79 27-82 -0-96 16 85 82 83 28-37 -1-51 17 86 82 84 27-81 -0-95 IS 87 .79 83 26-59 + 27 19 93 90 91 28-25 -1-39 20 90 90 90 27-05 0-19 1141 1138 Mean. . . +26-86 2d = 2279 Vs-Vo = + 26-99 Vo = + 0-38 Va = - 24-85 Vrf = - 0-24 log = -35774 log/ = 1-07349 log(Vs-Vo) = 1-43123 V = + 2 37 r = 77 SUMMARY OF COMPARATOR MEASURES OF /3 GEMINORUM 1373. Solar Standard. No. of Regions. Velocity. Residual O - C. Probable error of Single Region. 1360 .. 25 + 2 93 0'21 + 1'10 1461 25 +3'02 0'31 ~0'71 1461 23 + 2'23 + 0'49 81 1462 22 +2'85 -0 13 0'81 1462 25 +3'03 -0'31 0'77 1462 23 +3'18 0'46 0'79 1462 26 + 2'50 + 0'22 0'68 1462 23 + 2'52 4-0'90 0-74 1465 23 + 2'31 +0"41 1'02 1468 23 +2'30 +0'42 0'80 1517 22 +2'51 + 0'21 0'79 1519 17 +3'05 0'33 0'72 1520 17 +3'29 0'57 0'65 1524 17 +2'41 -f 0'31 0'84 Mean velocity + 2 72. Mean P. E. 0'80. Probable error of single measure = rh 0-24km. Probable error of mean velocity = rt 0- 065km. Plate No. No. of Regions. Velocity. Residual. Probable error of Single Region. 306 23 + T84 + 0'37 +0 - 63 373 2' 72 -0'51 0'80 417 23 1'41 + 0'80 0'68 .424 23 1-58 + 0'63 0'88 443 23 3 03 -0-82 0'84 452 23 1'70 + 0-51 0'74 460 23 3' 19 -0'98 ri4 472 17 1'99 + 0'22 0'94 .500 17 2 03 + 0'18 0'81 .502 23 2'43 -0-22 0-93 527 .' 16 2 37 -0'16 77 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a SUMMARY OF MEASURES OF 11 PLATES OF /3 GEMINORUM. 207 Mean velocity + 2 21. Mean P. E. 0'83. Probable error of plate = r 0-40. Probable error of mean = d 0-12. As the summaries and probable errors above show, the error of setting on a single region is on the average in the several measures of the plate No. 1373 d= 0-SOkm., and :>nly slightly greater db 0-83 for the other plates. Hartmann obtained a probable error f r0-67km., somewhat smaller than above. The difference may be due partly to his greater skill and experience in measurement and partly possibly to better quality of pectra. If a better spectrum than 1373 had been selected and it were measured with ,he best of the fundamental spectra, I have no doubt the probable error would be con- liderably diminished. The measures of the 11 plates of ft Geminorum give an indication of the syste- matic discrepancies to be expected in the production of the spectra, although some Blowance should, be made for accidental errors of measurement. A total range of l-8km. is shown and the probable error of a plate is rtO-40km. These plates made under average conditions, no special care being taken, and the plates are of iverage quality only. A systematic difference between these measures and other deter- minations by the old method of measurement at this, and other observatories of slightly rver a kilometre + 3 -5km. with micrometer microscope, + 2 .2km. with comparator is present. These plates have only been measured by the comparator, and hence it can- not be determined yet whether this difference is in the plates or in the method of measurement, but the latter seems the more probable. It is interesting to note in :his connection that there is a gradual and systematic increase in the velocity of the lifferent regions from the red to the violet in all the star plates measured, but no xplanation of the cause of this discrepancy can be offered. It is unquestionable that 1 this were removed the probable error of a single region would be materially reduced. Finally, it is probable that, as mora experience is gained with the instrument, the accuracy of the measures will be considerably increased. THE COELOSTAT TELESCOPE. Although the optical and mechanical parts of this instrument have been ready for nearly two years, the shelter and connecting passage and tunnel were not finally com- pleted until about July, 1908, and it was not possible to make any use of the installa- tion until some time after that date. The spectrograph, which is described by Dr. DeLury in Appendix C, was erected and adjusted as soon after as possible, but owing to the inferior quality of the grating, the work has been much handicapped. 25a 16 208 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 The telescope itself performs admirably and as it has not yet been described, it seems desirable to mention here its principal features. Essentially the optical parts of the installation consist of the coelostat mirror, which reflects the sun's light in a southerly direction to a secondary plane mirror, j which in turn reflects the beam north to a concave mirror forming a solar image 80 feet south in the basement of the observatory building. A general view of the coelostat and secondary mirror, and of the shelters and connecting passages for the beam is given in Fig. 13. The coelostat and secondary mirror are covered by a house on wheels, which can be easily rolled back (and is thus shown in the figure) by a convenient mechanism over the louvred passageway which contains the" concave mirror. Between the latter and the basement of the Observatory is another ventilated passage and a tunnel. The house and passages are constructed of wood, covered with galvanized iron painted white, and all very thoroughly ventilated by galvanized iron louvres to prevent as far as possible temperature stratification or disturbance in the course of the beam. It would have been preferable to continue the ventilated passage along the whole course of the beam from the coelostat to the Observatory wall, but this was not possible on account of the necessity of a driveway. This difficulty 'was overcome by making a tunnel for the last 20 feet, or so, through which the beam passes to the focus. As the latter is usually five feet or so outside the wall, this leaves an unventilated distance of about 15 feet, which apparently has no very serious effect on the definition. A general view of the telescope looking north is given in Fig. 14, and another view looking south towards the Observatory in Fig. 15. The coelostat has a plane mirror 20 inches in diameter which rotates, on an axis, in or parallel to its plane, which is parallel to the axis of the earth and driven by clockwork at half the diurnal rate. The whole instrument is moved bodily east and west by the sheave and cable, shown in the figures, on cast-iron ways resting on a cement pier. The purpose of this movement is to enable the coelostat inirror to receive the sun light more nearly normally by placing it towards the west in the morning and the east in the afternoon. The ways are long enough to permit of sufficient movement to prevent any intercep- tion of the return beam from the concave, which passes under the secondary mirror. The beam of sunlight from the coelostat mirror is reflected in a constant direction so long as the declination remains the same, but evidently any change in the declination of the incident light entails a similar change in the direction of the reflected light, and it is necessary to have a movable secondary mirror to receive this beam and direct it towards the image forming concave. This change of direction oJ] the reflected beam, due to the change of declination of the sun, is provided for by attaching the mirror to a carriage rolling on ways in a north and south direction, the mechanism for changing the position of the secondary being identical with that used! for moving the coelostat and the concave mirror, and being well shown in the figures. During the winter when the sun is low in the sky, the secondary has to be brought close to the coelostat, and in the summer away from it. The secondary mirror, also oi 20 inches diameter, can be quickly adjusted in inclination by quick and slow motions so as to send the beam directly to the concave mirror. The latter of 18 inches diameter and 80 feet focus is movable in the north and south direction over ways about 20 feet long, in order to be able to vary the position of the image for different purposes. It is also adjustable vertically and has slow motions provided for moving around a vertical and horizontal axis in order to place any desired part of the image, say, on the slit of the spectroscope or in any other required position. The beam of light from this mirror passes directly under the sec- ondary mirror through the opening in its support, and is inclined downward 3i, the same inclination being given to the ways on which the concave mirror carriage moves. This inclination was adopted in order to enable the coelostat to be raised a little above - 25a p. 208 PLASKETT ASTROPHYSICS. FIG. 14 CtElostat Telescope Mechanism, looking noith. PLASKKTT ASTROPHYSICS. 25a p. 208 FIG. In Coelostat Telescope Mechanism, looking south. REPORT OF THE CHIEF ASTRONOMER 209 fe ^SIGNAL PAPER No. 25a the surface of the ground, and to keep the beam some distance away from the roof of the tunnel. The coelostat was made by the J. A. Brashear Co., in 1905, for eclipse purposes, and the secondary and concave mirrors in 1907. The designs and drawings for the remainder of the mechanical parts were made by myself, while the mechanism was con- structed by the Victoria Foundry. It was found necessary, owing to the vibration of the secondary mirror support and carriage by the wind, to design one of a heavier pattern, which has been constructed by the same firm since the photographs were made, and entirely overcomes the difficulty. The definition given by this equipment is much better than was expected from the somewhat unfavourable conditions, such as the low position of the coelostat, and the presence of the unventilated tunnel through which the beam passes. Its location north of the Observatory is also objectionable on account of radiation or convection from the building, affecting the beam between coelostat and sun. However, as the position of the installation was the only one available, we were forced to make the best of these adverse conditions and as the result shows successfully. In the early morning and the late afternoon when the mirrors are in their normal condition the definition is very good, but this is soon deteriorated by the irregular figure produced by the heating action of the sun on the mirrors. However, by keeping them shielded from the sun's rays except during actual use, this causes no especial difficulty in solar rotation work. RADIAL VELOCITIES. The work of determining the radial velocities of stars has been actively carried on during the last year, the addition to the staff enabling a considerable increase in the number of measurements made, and in the amount of computational work accom- plished. So far as observing is concerned, however, the weather has not been as good as in the previous year. In April and May there were considerably fewer observing nights, many of them also being rendered practically useless by haze. June, July and August were good, but they were followed by three months in which very few useful spectra we^-e obtained owing to continuous dense smoke at first and afterwards to cloudy weather. The remainder of the year has been of about average quality. There have been photographed in the year, 1,010 spectra, 18 sun for use with the spectro- comparator and 992 star spectra on 160 nights. Of these 218 have been made with the three-prism, 698 with the one-prism and 94 with the new one-prism spectrograph. Of these spectra, 775 have been measured and reduced. Probably a number of (spectra made previous to April 1, 1908, have also been measured during the past year, S'but we have no record of the exact number. Detailed measures, which in this report have all been collected together at the iend (Appendix E), have been made of 635 plates, of which 581 are used in obtaining !the orbits of the five binary stars discussed below. The other 54 are measures of two ;8tars whose orbits are not yet completed. The remaining 138 plates measured are 'chiefly of spectroscopic binaries under investigation, but they also include a number of plates of some early type stars not known to be binaries. The five binaries discussed below with the number of plates used for each are : Star. Right Ascension Declination. No. of Plates. /3 Orionis h. 20 15 16 13 m. 10 06-2 30-4 56-5 49-9 - 8 - 1 + 27 + 31 + 18 19' 7 3 4 54 273 54, 103 106 45 + 43 in 1908 9 Aquilse a Coronae Borealis.. e Herculis 17 Bootes 25a 16i 210 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 The 34 measures of 8 Aquite which follow are given for the reason that there seems little prospect of obtaining an orbit and little use, owing to the uncertainty of the results and the small range in velocity, in carrying the work on this star any fur- ther. The binaries under observation here at present are given in the following table. In two of these stars T Tauri, B.D. - 1 1004, and \> Orionis, the work is well advanced, but on many of the others not much has yet been done : BINARIES UNDER OBSERVATION. R.A. Declination. tf> Persei . r Tauri . 7 Camelopardalis B. D. - 11004.. v Orionis 7 Geminoruin .... w. Ursse Majoris . . 93 Leonis 7 Corvi o Herculis B.A.C. - 5890.... a Ophiuchi 7 Aquarii h. m. 1 37 4 36 4 49'3 5 36 6 1-8 6 31-9 10 48-2 11 43 12 11 17 11 17 21-3 17 30 22 16 + 50 + 22 + 53 14 16 43 20 16 24 5 12 11 36 35 11 47 9 43 46 5 9 57 37 53 Mag. 43 4'2 4-7 5-1 4-6 2'9 4-7 4-8 3'3 37 4'8 2'9 4-1 Type. Ia2 Ib Vila Ib IVa.b VIII a Ia2 XII Via VII b XII XIII b Vila The majority of these stars have, as will be noticed, early type spectra and in many of them the lines are very diffuse; consequently many plates are required before a satisfactory orbit can be obtained, an example of this being given in the preceding table of the binaries completed, where the average number of plates used is well over 100. In the measures of stars not known to be binaries, those that were observed having in every case spectra of the hydrogen or helium type generally with diffuse lines, the following four stars were discovered to be variable in their velocity: NEW SPECTROSCOPIC BINARIES. Star. R. A. Declination. Mag. Type. 5 Herculis h. 17 22 23 3 m. 11 16-5 33 2 52 4 4- 24 _ ^ + 42 + 35 57 53 43 30 37 4'4 4'4 VII b VII a A I b 7 Aquarii i Andromedse Persei . . . . In addition to the above, ft Orionis is definitely announced as of binary character, but as it is more fully discussed later, nothing more need be said about it here. 8 Herculis. Practically the only lines measurable in this spectrum are the hydrogen series, and these are very diffuse and difficult to measure. Consequently, the measures are REPORT OF THE CHIEF ASTRONOMER 211 SESSIONAL PAPER No. 25a subject to much uncertainty, and it was only after several plates had been obtained that its binary character was established. The velocities are as follows: Plate Number. Date. Velocity. Plate Number. Date. Velocity. 1907. 1908. 839 June 12-79 - 27 1404 March 16 '93 - 44 894 27*74 - 9 1480 April 13 83 - 73 929 July 9 '66 - 35 1495 15-89 - 47 1512 22-89 - 57 1908. 1532 May 15-85 - 47 1541 18-81 18 1392 March 8'9 - 59 The variability in its velocity was discovered by Mr. Harper. y Aquarii. This star is of the hydrogen type, having Mg. 4481, Fe 4549, Ca 3934, in addition to the hydrogen lines, and the measures are consequently much more reliable than the previous star. They are: Plate Number. Date. Velocity. Plate Number. Date. Velocity. 1908. 1908. 1745 July 29-86 - 18 1790 August 17'81 - 40 1770 August 5 '81 8 1847 28-70 _ n 1779 7-81 4- 3 1858 31-77 + 23 Its variability was discovered by Mr. Cannon. i Andromedce. The spectrum of this star is similar to that of y Aquarii, having the hydrogen Mg. 4481, and K lines, although possibly not so well defined. Its variability was dis- j covered by Mr. Cannon, and it was announced in the Journal of the Eoyal Astronomi- cal Society of Canada, Vol. II., No. 5. I learned afterwards that it had been informally (announced by Prof. Frost at the Put-in-Bay meeting, of the Astronomical and Astro- | physical Society of America. Although present at the meeting, I had taken no notes jand had forgotten its announcement. The discovery here was consequently entirely independent. The velocities of all the plates measured here are given: Plate Number. Date. Velocity. Plate Number. Date. Velocity. 1908. 1908. 1772 August 5 ' 87 - 6 1954 November 9 58 1781 7-87 11 1963 13-60 + 14 1832 26-87 - 12 1969 n 16 69 + 29 1922 October 9 '76 - 36 1971 20-59 - 13 1928 12-71 14 1977 21-63 + 7 1939 19-63 + 6 1995 December 2 55 + 1 212 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 Persei. The spectrum of this star is of the helium type, and is principally characterized by the extreme breadth and diffuseness of the lines. Frost and Adams, in 1903, pub- lished the measures of some plates which agreed well within errors of observation in giving it a positive velocity of 85km. per second. They surmised that later plates might show the velocity to be variable. Consequently, I thought it desirable to obtain a few plates here, and their measures by Mr. Cannon soon showed that the star was a binary. I have since learned personally from Prof. Frost that this had been a long time established by them. The following are all the velocities measured here: Plate Number. Date, G. M. T. Velocity. Plate Number. Date, G. M. T. Velocity. 1 1908. 1908. 1946 J953 1958 1964 October 30 37 November 6 '66 9'77 13-65 4- 120 + 143 + 54 - 2 1974 1998 1999 November 20-83 December 2 '69 4'72 + 45 + 32 + 51 8 Aquilce. Mr. Parker has spent considerable time at work on 8 Aquila3 without being able to obtain a period, and it looks as if the small range, combined with the poor quality of the spectrum, will prevent any orbit being determined. Mr. Parker has also been unfortunate in the other binary on which he has been engaged, T Tauri, which has very bad lines in its spectrum and over which he has spent a great deal of time. He has, however, determined the period as nearly 1-5 days, but it has not been thought desir- able to complete the work until further plates are secured next season. Consequently no measures of it will be given in this report, but a summary of the measures and; some data concerning 8 Aquilse are given below, while the detailed measures are given in Appendix E. This star (a = 19 h 20 m -5, 8 = 2 55') was discovered to be of variable velocity by Campbell and Curtis from observations made at the Lick Observatory in 1900-03.* Observations were begun upon it here in August, 1906, and since then some thirty- four plates have been measured and computed. 8 Aquila? is taken as the typical star in Group XL, according to Miss Maury's classification.-!- The principal lines in the spectrum are those of hydrogen, iron, magnesium and titanium. All, and especially those of hydrogen, are broad and not defined, the region measured being from Hp to X 4005. These will be found in Table I. The range of resulting radial velocities, as seen in Table II. is not large ( - 15 to - 47kms.), and, as yet the period cannot be determined from the curve of the present observations. * L.O.B., 1903, A. J. XVIII., 306. t Annals Harvard College Observatory, Vol. 28. REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a TABLE I. 213 .TRINC IPAL LINES MK^ LSUKEU IJN AyiilLA;. Wave-Length. Element. Wave-Length. Element. 4861-527.. H 4274-922 Ti & Cr 4549'766.. Fe & Ti 4271-760 Fe 4634-139.. Ti 4260-640 Fe 4501-448 Ti 4246-9% Y 4481-400.. . Me 4227-010 Fe 4443-976 Tl 4216 351 Fe 4404 '927 Fe 4198-494 Fe 4395286.. Ti, V, Zy. 4143-i>28 Fe 1374-905 ' Ti 4102-000 H 4340-634 H 4071-901 Fe 4325-939 Fe 4063'756 Fe 4320-992 So 4045-975 Fe 4282722. .. . .'. Fe 4005-429... Fe TABLE II. TABLE OF OBSERVATIONS OF S Plate. Date, G. M. T. Velocity. 368 1906, August, 6 "73 -41 -g kma 377 i, 15'65 45'2 382 ti 24-65 45'1 390 Sept. 10-64 25'0 399 27-61 29'0 413 Oct. 23 57 37 7 803 1907, May, 31 '79 29'9 818 June 2 10 ' 80 42'8 904 July, 2 76 19'5 923 M 8'75 28'0 930 i. 9'68 15'6 JI38 ,. 10'68 18'6 966 n 25-68 16'5 980 Aug. 3'61 25'7 982 ,i 5'68 29'4 !l034 Sept. 6'65 25'4 1049 (a) ., 18-58 25'9 1049 (b) M 18'58 28'0 1543... 1908, May, 18 '83 21'9 : 1550 . ., 22'85 40 1 1575 June, 3 ' 83 28'2 ;1575 ,i 3'83 3 1 '6 1584 M 5'85 35-5 1633 H 24'77 29'5 1642 ti 26'78 39'8 1650 27'75 40*9 ;1660 July 3-77 21-9 J1678 i! 8'75 36'4 1690 ...... i. 10-77 26'1 1695... . it 11 '77 34'6 1703 M 13 '78 47 - 1753 n 31 '69 30'7 11754 n 31 '72 39"! 1768 29'7 1783 i. 'l573 31'9 1837 n 27 '62 -39'5 214 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 THK ORBIT OF ft OR ION IS. As was mentioned in rny report of last year, under a description and discussion of the effect of slit-width on the errors of setting, this star showed such a difference in the mean velocities obtained on two nights (mean of 10 plates on March 20, 24 -9km.; mean of 12 plates on March 24, 20 -6km.) as to lead to a strong suspicion of the varia- bility of its velocity. This suspicion was strengthened by plates obtained on other nights up to April 13, 1908, and it was decided on account of its brightness and its interesting history to follow it closely as soon as it again came into position where it could be observed. The radial velocity of ft Orionis was first determined at Potsdam by Vogel and Schemer* in the years 1888-1891, in the beginning of photographic determinations of radial velocity. From their measures of the 14 plates, velocities varying between about + 3 and + 34kms. per second were obtained. They suspected a variation in the star's velocity due to orbital motion, but were unable to obtain evidence of its periodi- city, and the accuracy of these early measures was scarcely sufficiently high to decide the question. The next published measures of the star's velocity were by Frost and Adamsf from plates obtained in 1901-1902. They found values ranging between + 14-9 and + 23 -4km., but they attributed this range to the character of the lines in the star's spectrum and concluded that their results showed no indication of variability in velo- city. The measures of 5 plates of ft Orionis obtained at the Lick Observatory^: indi- cate a range of 10km. from + 15 to + 25km., in its velocity, but Campbell and Curtis in discussing these measures attribute this range to the small number of lines avail- able, to their poor quality, and to over-exposure of some of the negatives. They con- sider that proper exposure would considerably reduce the observed range, and conclude that their results do not give any evidence of variability of velocity. However, a recent personal communication from Prof. Campbell informs me that they have sus- pected variation, but owing to press of their regular programme have not followed up the matter. There seemed to be no question of the smalmess of the range in velocity, if any, and it was evident that the only hope of obtaining anything definite, considering this! arid the fairly large accidental errors of a velocity determination owing to the charac- ter of the lines of the spectrum, was to obtain several plates on each night the star was observed and use their mean velocity as the velocity of the star at their mean epoch. As the star is bright, a spectrum can be obtained in ten minutes or less with the three-prism spectrograph, and in about two minutes with the one-prism. Conse- ; quently not much time is required to obtain half a dozen plates and unless the period is very short no error due to change of phase can enter. The probable error of a night's observation will by this means be considerably red\iced and a much better chance obtained of determining its period of variation. Plates were accordingly obtained whenever possible until the star became inac- cessible in April, 1908, and observations were continued during the present season until March 23, 1909. Owing to the very smoky and cloudy weather last fall, very fe 2128 13 15 36 320-65 + 30-2 + 61 2129 13 15-41 320-65 + 15-7 - 8'4 2130 13 15-46 320-66 + 28-8 + 4'7 2141 15 14 54 322-62 + 18'6 + 7'3 2142 15 15-11 322-63 + 24-5 - 14 2143...' 15 15-15 322-63 + 27 2 + 1-3. 2144 15 15-19 322-64 + 21-8 - 41 2151 16 12-25 323 52 + 31-4 J - 5-3- 2162 16 12-36 323 52 + 27'6 + 1'5 2153 16 12-44 323-53 + 34-4 + 8'3 2154 16 12-52 323-53 + 40-9 + 14 '8 2155 16 12'59 323-54 + 33 + 6' 2156 16 13 12 323-55 + 35'8 + 9'7 2157 17 13-48 324-57 + 29-9 + 39 2153 17 13 '56 324-58 + 26'2 + 0'2. 2161 18 12-41 325-53 + 37'1 +ir& 2162 18 12-46 325-53 + 31 3 + 5-7 2163 18 12-51 325-53 + 28 3 + 2-7 2164 18 13-06 325-54 + 35-8 + 10'2 2165 18 13-10 325-55 + 31'2 + 5'6 2166 18 13-14 325-55 + 30-5 ~ 4 !> 2177 26 10-36 333-44 + 24'6 + 3'4 2173 26 10 51 333 45 + 17'8 - 3'4 2179 26 10-56 333 46 + 24-9 + 3'7 2180 26 11-01 333-46 + 23'5 + 23 2181 i 26 11-11 333-47 + 22'4 + 1'2 2184 26 11-16 333-47 + 16'2 - 50 2183 i 26 11-21 333-47 + 20'5 - 0'7 2184 28 11-21 335-47 + 16'3 - 3'6 2185 , 28 11-25 335-48 + 23'2 -L- 3-3 2186 , 28 11-29 335-48 + 14-2 - 5'7 2187 , 28 11-41 335-48 + 14-3 - 5'(> 2188 , 28 11-44 335-49 + 10'6 0-3 2189 , 28 11-47 335-49 + 18'4 - 0'9 2195 , 29 12 53 336'54 + 14-9 - 4'3 2196 29 12'57 336 '54 + 17'9 - 1'3 2197 29 13-01 336-54 + 26'4 - 7'2 2198 29 13-05 336 54 + 22'1 - 29 2201 i 30 12-29 337 52 + 14-0 4'7 2202 30 12-41 337-53 + 17 '3 - 1'4 2203 , 30 12-45 337-53 +25-0 + 6'3 2204 , 30 12'48 337-53 + 14'2 4'5 2205 i 30 15-47 337-66 +21 + 2'3 2206 2207 30 30 16-04 16 24 337-67 337-68 + 22-6 + 22'3 + 41 + 3'8 2211 i 31 17'16 338 '72 + 19'8 + 1 "2 2212.. 31 17-20 338 '72 + 23'2 + J'6 2213 31 17-24 338 '73 + 16'0 26 2214.. .. i 31 17'29 338 '73 + 16 "6 2"0 2215 .. . February 2 11 '14 340 "47 +24'8 + 4'6 2216... n 2 11'23 340'48 +23"! + 2'9 2217 i 2 11 '26 340 "48 +23 6 + 3'4 2218 2 11-29 340 "48 + 22"5 + 2"3 2219 2 11 41 340 '49 + 16'5 3-7 2220.. 2 11-45 340-49 + 21'5 + 1'3 2236 6 12'29 344 ' 52 + 18 '2 - 7-7 2239 6 12-50 344 ' 53 4-20-0 5'9 2240 . i 6 12'52 344-53 + 2l"0 4-rt 2241 6 16 12 344-68 + 21'9 4"0 2242 6 16 '43 344 70 + 19 1 6'8 2243 7 15-11 345'63 + 21 ' 5"l 2244 7 15-25 345 64 + 21-9 - 42 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a ft ORIONIS. SUMMARY OF MEASURES. Continued. 219 Plate Number. Date. G.M.T. Julian Date. Velocity. Residual. 2245 1909. Kebruary 7 15 37 2,418,345'65 4-18'0 - 8'1 2249 8 13 32 346'56 +31-6 + 5'2 225(1 i 8 13 36 346-56 H-25'9 O'O 2251 8 13'41 346-57 +21'8 - 4'1 2252 8 14'01 346-58 + 17 6 - 8'3 2203 . . .. t 8 14 05 346-58 + 24'1 - 1*8 2251 8 14'09 346.59 + 23'3 - 2'6 22*55 10 12 07 348'50 +29'6 + 4'4 22C . 10 12 12 348-51 +23 3 .- 1-9 2267 t 10 12 16 348'51 + 16'9 - 8-3 22'.h , 10 12'21 348'51 + 12'8 -12'4 2269 i 10 12 33 348-52 + 20'3 - 4'9 2270 10 12 '37 348 '53 + 23 - - 2'2 2272 . .. , 11 11 26 349 48 + 18'9 - 5'8 2273 1 11 11'32 349 48 + 33'4 + 8"7 2274 2275 11 11 11-35 11'38 349-48 349-49 + 30-8 + 19'7 + 6-1 - 50 2276 11 H'46 349-49 + 17"3 - 7 4 2277 . 11 11 '49 349-49 + 23'5 - 1'2 2278 2279 .... '.'.'.'.'.' 13 13 12-27 12 '49 351 52 351'53 + 22 2 + 22'0 - 14 - 1-6 2L'H' , 13 12'53 351-54 + 21'4 - 22 2284 20 12'29 358 '52 + 17"7 - 1'4 22S5 20 13 '05 358'54 + 22'6 + 3'5 22M1 20 15'12 358'63 + 19'8 + 0'7 22>* 21 12 '51 359-53 + 21'0 + 2'3 2289 21 13'07 359 54 + 18 "2 0'5 2290 . 21 13'17 359 4 55 4. 18 -4 0'3 2291 21 13 27 359 56 +18'7 O'O 2292 22 12 02 360'50 + 19'7 + I'l 2293 22 12 '15 360 '51 +25 '1 + 6'5 2294 i 22 12'30 360'52 + 20"2 + 1'6 2295 2309 22 , 27 12 45 11 '35 360-53 365 '48 +20-2 + 22'0 + 1-6 3'4 2311 . . 28 11"56 366 "50 + 22'2 3'8 2312 2313 28 i 28 12-07 12 "18 366-50 366 '51 + 22-0 + 23-7 - 4-0 2'3 2311... 28 12 '27 366 ' 52 + 25'3 0'7 2315 .1 28 12 '39 366 '53 +22'4 3'6 2316 ii 28 12'50 366 "53 + 22'8 3'2 2317 2318 .... March 2 ii 2 11-05 11 "19 368-46 368 "47 + 25-9 + 24 "4 00 1'5 2319 ... n 2 11 -29 368 "48 +24'2 1"7 2320 3 11'36 368 "48 +21'6 4'3 2364... ii 13 12 "12 379 ' 51 + 18'6 I'l 2365.... 2366 13 ii 13 12-24 12 '36 379-52 379'52 + 18-4 + 20'3 - 1-3 + 0'6 2367 13 12 -46 379-53 + 17 "6 2'1 2368.. t. 13 12 '57 379'54 + 19 "3 0*4 2372 n 15 11 '45 381 '49 + 16 '9 1'8 2373 2374... 2375.... 2376.... 15 15 15 n 15 11-56 12-05 12-13 12 "21 381-50 381-50 381-51 S81 ' 52 + 20'5 + 17'6 + 18-9 4-1fi-9 + 1-8 - 1-1 + 0-2 2'5 2386... . 11 18 11 "42 384 " 49 + 19 '5 I'l 2387 * M 18 11 "52 384 "50 + 20"0 0*6 E388 .t 18 12 '02 384'50 4-21 7 4-V1 2389 .. n - 18 12 '12 384 "51 + 21"0 + 0"4 2390. . . 20 12 "16 386 ' 51 4.90-0 9- 1 2391 . . n 20 12 '26 386 "52 4- 1 8 3 fi-0 2392 . n 20 12 '38 386 "53 + 23-4 0"9 2393 . n 20 12 '48 QQfJ W 4-91 '0 2-4 2394... n 20 12 "58 QQf! -K.A i OQ-1 1 <> 2397 n 21 13 "38 QQ7 Kf. i O9-O 1 -fi 239x .. ii 21 1Q-4C y&7 -t\7 i OK-O O'^ 2399... 21 14-00 3R7-?i8 4-94-8 - 0-7 220 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 /3 ORIONIS. SUMMARY OF MEASURES Continued. Plate Number. Date. G.M.T. Julian Date. Velocity. Residual. 2400... 1909. March ....21 14-14 2,418,387'59 + 25'5 O'O 2402 22 11-51 388*49 + 26'0 O'O 2403 22 12'02 388'50 + 25'0 I'O 2404 22 12'13 388'51 + 21 "1 4'9 2405 22 12 35 388 '52 +21 '2 - 4"8 2420 23 11'46 389 49 + 23'1 - 3'0 2421 23 11-57 389'50 +24'4 - 1-7 2422... 23 12-05 389'50 -u25'9 0'2 2423 23 12 '13 389 '51 + 26'2 + O'l 2424 23 12'27 389 52 + 25'5 06 2425. 23 12'38 389 '53 -t-25"7 0'4 In the preceding table are given the plate number, the Greenwich mean and Julian dates, the weighted mean velocity for the plate, and finally the residual obtained by scaling from the final velocity curve. The velocities on each night were obtained by taking the weighted means of the plate velocities, the weights being assigned, as before stated, partly on the basis of apparent quality, partly according to the internal agree- ment of the measures. In the following table of mean velocities are given various data concerning the observations of each night, as the date, Julian date, velocity, phase, the number of plates, the dispersion used, the weight assigned and finally the residual obtained by scaling from the curve: REPORT OF THE CHIEF ASTRONOMER 221 SESSIONAL PAPER No. 25a |8 ORIONIS. SUMMARY OF MEAN VELOCITIES PER NIGHT. Date. Julian Date. Mean Velocity. Mean Phase. No. of Plates. Spectro- graph. Weight. Residual. 1908. Jan. 20 2,417,961-65 22-3 (55 24 IL 16 + 1-40 2? ... 968-71 19-7 7'71 12 III S 6 -1-50 March 20.... 2,418.021-54 24-9 16-74 10 IIIL 10 + 0-45 24.... 025-54 20-6 20-74 12 6 -1-47 30.... 031-52 15-1 4-82 4 6 -3 46 April 3.. 035-52 27 3 8-82 4 4 +3-87 M 4 036.52 28-2 9-82 3 3 +3-28 is!".' 045-52 24-2 18-82 3 3 +0-93 Sept. 7 192 92 27-1 12-92 2 2 + 1-10 Oct. 13 228-92 16-8 5-12 4 5 -1-76 Nov. 21.... 267-79 22-3 19 4 3 + 1-08 28.... 274 69 21-4 7-09 3 2 + 1-32 Dec. 1 ... 277-77 20-1 10 17 4 1 -5-19 5.... 281-69 25-9 14-09 4 2 -1-36 21.... 297-68 23 8-18 4 IL 2 +0-85 22.... 4549-642 1204- Mir 4481-400 1151 H 4340-634 1044 Fe 4233 328 964 He 4143 928 898 Si 4131 047 889' Si 4128-211 887' H 4101-890 868' H 3970-177 774- Ca 3933-825 749' Practically all the plates made have been used in the discussion, even although one or two have not been of the best quality, No. 865 being a case in point. In the preliminary curve for this year (P = 17-120) No. 873 gave an abnormally high residual ( - 28km.) and following out a suggestion of Mr. J. S. Plaskett, to whom I am much indebted for help during this work, the result was omitted from consideration in the least-square solution, as an excessive residual tends to distort the elements out of all agreement with the mean values, as obtained from the remaining observations. The following table gives all the data of the plates, the phase being reckoned from periastron, Julian Day 2,417,731.504, using the period finally determined, 17-1,12 days. TABLE II. MEASURES OF 6 Plate No. Julian Date. Phase. No. of lines. Wt. Velocity. Residual. 803.... 1907. 2,417,727-814 13-425 4 5 - 24 + 0'2 '819.. 737787 6-284 4 5 - 39 + 31 i [841 739-836 8-333 4 5 - 38 0-4 854 741-813 10-310 4 5 - 42 - 5-9 i ' 865 747778 16 275 1 2 + 45 + 16-0 905 759-777 11-162 5 4 - 40 - 5-2 924.. . ... 765777 0-050 5 4 4- 30 -19-5 931 766-711 0-984 7 5 - 30 + 9-8 942 770-703 4-976 4 A - 40. + 5'7 946 . 773*713 7-986 3 3 - 43 - 5-0 959 777764 12-037 5 - 40 - 7'8^ 969 784760 1-921 4 4 - 40 - 1-8 ; 1001 798-660 15-821 5 4 + 19 + 6'2 1012.. 801-692 1-741 4 3 - 39 - 20 1013 803-573 3 622 6 4 - 51 l-l 1027 815-630 15-679 3 3 + 10 + 1-1. ' 1028 815-669 15-718 2 5 + 11 + i-o 1033.. 825-612 8'519 4 3 - 38 - 06 1038.. 831-635 14-572 4 f - 8 t 36 1043 833-673 16 610 7 3 + 55 + 10 5 1050 837-614 3-438 4 4 - 47 - 0-4 1072 849-543 15-367 5 4 + 3 1-3 1073 849-559 15-383 4 5 + 4 + 2-1 1074 849-589 15-413 6 5 7 9-4 1080 850-502 18-326 3 2 + 28 - 26 1081.. 850-521 16-345 5 3 + 33 ! O'S 1082.. . 850-548 16-372 6 4 + 30 3-8 1085 850-613 16-437 8 5 4- 25 -10-5 1086 850-642 16-466 5 3 + 36 - 10 1089 851-528 0-240 5 4 + 18 --12 1091.. 851-570 0-282 3 2 + 28 + 9-2 1092... 851-589 0-301 5 2 + 23 26 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a TABLE If. MEASURES OF 6 AQUIL.E --Continued. 227 Plate No. Julian Date. Phase. No. of lines. Wt. Velocity. Residual. 1093 1907. 2,417,851-605 317 5 3 + 26 + 2-6 1094 851-625 337 2 1 + 12 - 9 iioo 867-510 16-223 1 1 + 28 + 1'7 1101 867-574 16-287 3 3 + 33 + 40 1106 . 874-535 6-135 4 2 - 44 4- 1-4 1128 884-437 16-038 5 5 + 16 - 4-0 1129 884-452 16-052 5 5 + 32 T-11'6 1146 . 896-500 10-988 4 2 - 33 - 2'8 1149.. 898-448 12-936 3 1 - 31 - 3-4 1150.. 898-526 13-014 5 3 - 20 + 7'2 1154 899-445 13-933 4 3 - 18 + 1-8 1155 899-458 13 946 3 2 - 30 - 10-0 1157. 903-529 0-905 3 3 - 33 + 3'9 1533 1908. 2,418,077-871 4 126 5 3 - 50 - 3-0 1544. 080-873 7-128 2 2 - 37 + 3-0 1576 096-857 6-000 3 3 - 48 - 5-0 1583 098-821 7'964 5 3 - 31 -f 7-0 1604 105-814 14-943 7 3 - 11 - 5-0 1605 . 105-843 15'000 6 3 - 15 -lO'O 1626 115-774 7'805 7 4 - 29 + 9-3 1634 . 117-824 9'855 7 5 - 29 + 7-5 1^43.. 119-821 11-852 6 5 - 30 + 3-0 1651 120781 12-812 9 5 - 32 - 4-0 1659 126-729 1-648 2 2 - 36 - 0-5 1679.. . . 131-785 6'704 5 3 - 39 + 2-0 1691.. 133-812 8 731 5 3 - 41 - 4-0 1696 '. 134-799 9'718 5 4 - 34 H- 2-5 1704 136-818 H'737 6 2 - 33 + o-o 1708 W764 12-683 5 4 - 26 + 33 1716. 138-809 13'728 7 5 - 19 + 2-5 1727 148-687 6 494 5 5 - 37 + 4'6 1730 149-735 7-512 5 4 - 39 -f- 0-0 1731 149755 7 '562 5 3 - 41 - 2-2 1732 150-760 8'597 5 3 - 33 + 4-3 1733 150-840 8-617 2 2 - 41 - 3-8 1735 151743 9-551 6 3 - 43 - 6-5 1736 151-756 9-564 2 1 30 + 65 1747 153-740 11-547 5 3 - 31 + 3-0 1755 154-744 12-551 5 2 31 - i-o 1756 154-764 12*571 5 3 - 26 + 4-0 1762 159-619 316 7 3 + 35 +10-0 1766 159-687 0-384 4 3 + 33 + 13-0 1767 159-722 0-419 5 3 + 16 + 3-0 1769 159*784 481 3 2 4- - 8'0 1776 161-708 2 395 4 2 - 41 + 1-5 1777 161-740 2 443 7 4 - 39 4 4-0 1789 , 171-763 12-458 5 3 - 21 + 9-0 1794.. 173-697 14-392 5 3 . - 24 -10-0 1799 174-635 15-328 8 2 + - 10 1800. 174*658 15-351 6 2 2 - 3-0 1801.. 174-695 15-398 6 3 + 7 + 4-5 1807 175-581 16-273 6 2 + 29 + i-o 1808 175-605 16-297 7 2 + 26 - 3-0 1810 175-645 16-337 5 2 + 22 -10-0 1811 176-645 0-228 5 3 + 35 + 4-0 1812.. 176-664 0-247 5 1 4- 39 +10-0 1813 176-681 0-264 2 + 35 + 6'0 1814 177-659 1 242 6 4 - 30 - 1-5 1815 = . .. 177-680 1-263 8 4 33 - 40 1822... 178702 2'285 7 5 - 35 + 7'0 1835. 181-584 5'165 5 4 - 49 - 30 1864.. 188-678 12'259 8 5 - 33 - 17 1875.. 193-529 O'OOO 5 4 + 51 - 20 1876.. 193-570 0'040 5 4 + 51 + i-o 1878.. . . 2,418,196-625 3-094 5 4 - 48 - 2-0 228 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 The observations of 1907 and 1908 were grouped separately and the period which suited best was 17-120 days. The phases for this period were computed, being reckoned from an initial epoch T , Julian Day 2,417,727, the date of the first observation. The observations of the two years were now combined and grouped into 18 normal places. Weights were assigned to these groups depending not only upon the sum of the weights of the individual plates, but upon the number of nights involved. The maximum weight was taken as 5. In the weighting of the individual plates, not only the quality of the plate per se, but the agreement among the various lines was taken into account. The groups are given in Table TIL TABLE III. NOEMAL PLACES. Mean Phase. Mean Velocity. Wt. Mean Phase. Mean Velocity. Wt. 1'09 -22-3 3 5-49 -31-3 2 2-13 -11-7 1 6-47 -38'2 3 2-66 + 0-7 3 7'96 -48-9 2 3-09 + 13 3 1 9 46 -44'5 1 3-42 + 24-9 2 10-73 -40-5 2 3'72 +34-3 3 12-05 -36 4 2 4 31 +51-0 1 13-93 -37-4 5 4'54 +33-6 1 16-28 -33-0 2 4-72 + 22-5 3 17-05 -26-7 3 Using the graphical method* of Dr. King, various values of e and to were tried, those finally decided upon as suiting the grouped observations best being e = 680, w = 20 , JT = 49km. and time of periastron passage, T, 4-30 days from initial epoch. Thus for preliminary elements we have : P = 17-120 days e =0-680 to =20 T = Julian Day 2,417,731-30 y = - 25 -3km. With these elements it was decided to make a least-square solution for the normal places. Using the differential equation of Lehmann-Filhes-f /d z\ I -T 1 = sin u sin v o I -T 1 = oy + (c os u + e cos w) o K + I cos o> -- ; -- ^ (2 + e cos v) IKoe K + I ; -- - [sin u + e sin u = 100ge v = iosr W = 10&o * Astrophyeical Journal, XXVII., 125, 1908. t A+ronomische Nachrichten 3242. Final elements (simple solution). REPORT Or T11K CHIEF ASTRONOMER 229 SESSIONAL PAPER No. 25a There result the following normal equations : 40-000a;4- 9-571j/- 15-914z-11.075 + 5-696V + 4-981U-+ 18-200 = + 16-015y- 19-3402- 13- 924tt + 6-444v + 2-043W- 6-419 = + 242-6972 + 11 .554it - 327-008V + 255 -472; + 14-267 = ,+ 19-651 it- 4-122t;+ 1.212w- 4-459 = + 486.538V-372-234M-- 36-352 = + 413-976K'- 102-105 = Whence the corrections to the first approximations: Sy = -0-6 km. Be = + -Oil SIT =+ 2 - 1 km. 8T = + 134 days. P=- -004 days. 8w = 5-27 The resulting elements with their probable errors, as determined at a later stage, are: P= 17-116 days -008 days. e = 0-691 d= -017 a>=25-27 riz 2-l T = J. D. 2,417,731-434 =fc -100 days. K= 51.1 km. dt 3-20 km. y = -25-9km. d= 0-64 A= 83-0 km. B= 19-2 km. The residuals from the curve using these corrected values of the elements seemed themselves to lie on a curve, which repeated itself approximately twice during the period of the principal star and having an amplitude of about 8 km. The way the residuals from the observed velocities grouped themselves was not mere chance, there was no doubt that there was some secondary disturbance. The assumption was therefore made that there was a third body whose period was commensurable with the period of the principal star, it going through all its phases in half the time required for that of the principal star. The orbit of the third body was considered circular and the secondary curve taken to cross the primary from above at a time T', Julian Day 2,417,732-634. Taking K f as 4km. and considering as the angle at any time from T' the extra terms in the differ- ential equation are: - sin $dK' +*pr K'. cos $. dT'. Correcting now our values of the computed velocity for each of the eighteen normal places by an amount representing that due to the third body we have a new set of eighteen observation equations connecting the eight unknowns. In these equations, for sake of homogeneity, we put x = 8y y = dK z = -^-? - 8fi = 13525-67 ftp ( I* - e y% u = K . de V .W 49 -355 37*. w = K . oo) y = oA" v' = ' 2 ~ A" . ^7" 2-937 230 9-10 EDWARD VII., A. 1910 There result the following normal equations: 40'OOOa; +. 9'394t/ - 16'283s + 15-353.V - 19'924z + 176-1840 -22'704u -28-003M + 20-361M +82-772w + 24-41 It- + 405- + 7-o2Stt' + 3 349i/ -- 33 400 = + 016w -f. 11- 548?/' + 2- 222r' 4 50 734 = + 43 '949w 7 ' 554V -27- 991t/ - 30 492 = 4 '072w - >- 165/ - 4 273r' -102-683 = -17 105w - 6872/' + 9 534v' _ 8 337 = + 17. 037w + 2- 279?/' -10 776r' 4 9 934 = + 20' 463//' 4- 1 950i-' + 54 446 = (I + 19 533r' - 1 '088 = II Whence the following corrections are obtained : 8T = + -0?0 days. 8 y = - 0.-01 km. SK= -L4 km. 8P= --0017 days. 8e = + -007 = -l-Skm. = +.159 days. The resulting values of the elements with their probable errors, as determined at a later stage, are: P = 17-114 days =t -008 days e = 0-698 =t .017 w = 25- 39 it; 2 -45 T = J. D. 2,417,731-464 -092 days. K = 49-7 km. rb 3 -31 km. First approximation (solution y =-25-91 km. zt 0-66 km. [ (with secondary oscillation.) T- J. D. 2,417,732-793 -. -349 days. K'= 2-7 km. rt 1-02 km. A. = 81-04 km. B= 18-36 km. The size of the corrections in some of the elements, and the fact that the residuals (computed observed) as obtained direct were not in all cases in close agreement with those obtained from the differential equation, i.e., by substituting the values of the corrections in the observation equations, made another solution necessary. The values of to and y were, however, considered established as the corrections were very small and the remaining six unknowns were, with the last elements as the basis, formed anew into eighteen observation equations. In these equations y = 100 K (1 - > K .de K (1 - ,)! a/r'. . 8T = Ar-.ar 13534-86^. 49 6906 1 9825 dT'. There result the following normal equations: 14-733*/- 19-8892-28-221W+ 3- 499 v + 11.503/4 -938y'+ 1-153 = + 174-454z + 23-938w - 61-517v - 10.663/ - 26-344^ + 17-185 = + 87-120w- 4.059V- 23.403?/'- 2-458i/+ 7-668 = + 23.7080+ -794/+ 9-359t/- 9-616 = + 21-4110'+ 1-2901/+ 1-868 = + 18-584v'- 4-992 = REPORT OF THE CHIEF ASTRONOMER 231 SESSIONAL PAPER No. 25a Whence the corrections : 8K= -0-02 km. 8P= -0-0022 days. 8e = +0-0037 ST = +0-039 days. $K' = -0-05 km. 82" = + 0-080 days. The corrected values of the elements with their probable errors, as determined at this stage, are : P = 17-1121 days rt -005 days ") 0-6943 == -013 25- 39 J. D. 2,417,731-503 zhr -070 days 49 -68 km. H= 2-28 km. - 25.91km. J.D. 2,417,732-873 -416 days 2-65 km. rb 0-86 km. 80- 84 km. 18- 52 km. e = T = K = K K' = A = B = Second approximation (solution with secondary oscillation). This solution should have been sufficient, but when substituting directly in the observation equations and comparing the residuals with those obtained in the ordinary way, there was one fairly large difference 0-40km., two were 0-30km. and the rest varied between 0-0 and 0-2 km. Furthermore, the probable errors of some of the quantities, particularly K, seemed too large. It was decided then to compute the probable errors corresponding to the previous corrections made. They are collected in the accompany- ing Table IV. : TABLE IV. SUMMARY OF CORRECTIONS. Elements. Preliminary Values. First Corrected Values. Second Corrected Values. Third Corrected Values. P. . 17'120d 17'116d + '008 17 '114 d + - 008 17'112d + '005 e 0'680 0-691 + '017 0'698 + '017 Q'6943 + '013 5km. +0'86km fT 485 km. 292 km 251 km. 235 km. The values for P, y, T' and K' were now considered determined. The probable errors, especially those in K, did not seem to be as low as they should be. As the prob- able error in CD in the later determination was larger than in the preceding one, it was thought advisable to take e, M , T and K and see if by another solution lower prob- able errors would be had, and a better agreement between the ephemeris and equation. 232 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 As before, for the sake of homogeneity, let y = Ade z = Kd< K (1 - )! ' = 48-930737'. And the resulting normal equations are: 14-480z-28-036?/- -077z + 3-931w-3.236 = 85.688t/+ -38?z - 3-660w + 4-604 = 17.243s -17-072M- 1-533 = 24-149W + -080 = from which corrections result as follows: 8K = + 0-29km. 8e = + 0-0009 &0 = + 0-1743 8T = + 0-0013 days The final elements, taking into account the secondary oscillation, are then as fol- lows. The Allegheny results as discussed later are, for purposes of comparison, given here : P = e = CD = T = K = B = a sin i = P' = T' = K = a' sin i' = OTTAWA. 17-112 .005. 0-695 =t -010 25-57 rfc 1.54 J. D. 2,417,731-504 -024 49-97 km. =t 1-35 km. 25-91 km. 0-66 81.31km. 18- 63 km. 8,452,100 km. 8- 556 days J.D. 2,417,732-873 =fc -416 ALLEGHENY. 17-117 -0042 0-685 =t -Oil !7-53 =t l-58 1907, Aug. 28, -697 == -034 dys. 44-69 km. =t= 1-15 km. - 30-10 km. , 73.88km. 15-50 km. 7,665,000 km. 8-558 days. 1907, Sept. 9, -176 -368 days time when secondary crosses primary from above. 2- 65 km. rt 0.86 2-39 km. =t 0-77 km. 311,800 km. 281,000 km. What seems peculiar is that the least-square solution diminished the period in each case, although from a comparison of the 1907 and 1908 observations, when plotted the period would seem to be fixed about 17-120 days. The successive approximations in each case decreased the sum of the squares of the residuals, as seen from Table IV. The final approximation gave ^pvv =238 -3km., practically the same as the previous one. The agreement, however, between the equation and ephemeris is much improved, the greatest difference being 0-27km. ; the average 0-lokm. and the probable errors are much lower. Table V. contains the phases for the normal places, reckoned from peri- astron with the period finally adopted, 17-112 days; the corresponding velocity with its weight, and the residuals as computed directly. 25a-p. 232 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a TABLE V. NORMAL PLACES. 233 No. Mean Phase from T Mean Velocity. Wt. Residuals C - I.. 13-810 -22-33 - 3 +1-85 2 14-871 -H'75 1 + 4'2l 3 15'378 + 0'66 3 +0'85 4 15-740 +13-33 1 -3 21 5 16 143 +24'87 2 -1'55 6 16 385 + 34'34 3 -0'44 7 0-019 + 51-00 1 + 0'38 8 0-166 + 33-60 1 + 4'75 9 0-346 + 22'48 3 -3 03 10 1 102 -31 31 2 +5'95 11 2-107 -38'20 3 -3'16 12 3-533 -48 93 2 + 1-93 13 5 070 -44-50 1 -1'17 14 -357 -40-50 2 -1 53 15 7'694 -36 42 2 -2'39 16 9-527 -37'38 5 +0'36 17 11-932 -33 00 2 + 07 18 12*713 -26'74 3 -2'3l The curve representing the final elements is shown in Fig. 17, the dotted lines being the velocity curves of the primary and secondary components and the heavy continuous line the resultant of these two. The final solution reduces the quantity 2,pw of the residuals for the normal places from 485 to 238-3. The least-square solutions, with the assumption of a secondary disturbance, seem, therefore, to have materially improved the values of the elements. The probable error of a normal place of weight unity as determined by r = -6745 2 pw where n is the number of normal places and p. the number of unknowns is zb 2.75km. The probable error of a plate as derived from the residuals in last column, Table II., which are scaled directly from the curve is for the 1907 observations dt 4-5km., and for those of 1908 =t 3-5km. Grouping the two years together the probable error of a plate is =b 4 -Okm. Previous Observations. There remains a discussion of M. Deslandres' observations of 1901 and 1902. These were tried in connection with our 1907 observations to determine the period more accurately than could be done by using our own alone. The only period which suits Deslandres' observations alone is the one which he suggests, viz., 16-7 days. If the two observations of 1901 were omitted the other observations will give a better curve when a period of 17-112 days is used. Fig. 18 shows Deslandres' observations using his period of 16-7 days. Fig. 19 shows his 1902 observations using our period of 17-112 days. He suggested an eccentricity of about 0-6; such a value for e with K = 45 km. and w = 27, gives a curve represented by the broken line in Fig. 18, while a similar value for K and w, with an eccentricity 0-4 is represented in the con- tinuous curve and appears to suit the observations as well as, if not better, than the other. The velocities he gives as relative only ; I have added 14 km. to each to bring them into agreement with the general run of mine. As his measures depended upon one line only, A 4481. and among themselves gave a more or less uncertain determination of the elements, I decided in my preliminary determination to confine myself to our own observation?. Xow that a definite solution lins been secured, it is well to look at them anew. For convenience the data is repro- 234 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 duced here, the tenth of a day being assumed. As stated before, 14km. is added to each velocity determination. The phase with the period 16-7 days is reckoned from the date of first observation of 1902, being Julian Day 2,417,964-4, the phase with the period 17-112 days is reckoned from my own periastron time. M. DESL ANDRES' OBSERVATIONS. Julian Date. Phase P = 16-7. Phase P = 17112 Velocity. 2,415,568-5 , 4'7 10 '221 + 11 583'5 30 8 109 + 34 964-4 O'O 12-545 - 2 969'4 5'0 '0-433 - 36 971-4 . 70 2 433 - 46 982-4 . 13 13-433 6 989-4 8-3 3-321 - 40 2,416,010-4 12'6 7'209 - 39 011-4 ..* 13'6 8'209 - 36 012-4 14'6 9-209 - 43 015-4 0'9 12-209 - 25 020-4 -. 5'9 D'097 - 22 029-3. . . . 14'8 8-997 - 31(? 040-3 9'1 2-885 - 46{? 047'3 16'1 9-885 - 24 048'S. 04 10 885 052'3. 44 14'885 + 39 054'3. . 6'4 16-885 - 44 057-3.. .. 9'4- 2-773 - 48 069'3- 4'7 14-773 + 10 071 '3 6'7 16-773 - 26 072-3. 7'7 0-661 - 50 076-3 11'7 4'661 - 47 086-3 50 14'661 + 2 088'3. . 7'0 16 661 - 15 2,416,095-3. .. . 14'0 6-549 - 54 It is rather hard to say how best to make use of these early observations. Though the measures are liable to accidental errors of considerable magnitude they may, owing to the interval of some six years which has elapsed between the two series of observations, have an important bearing on whether or not any changes in the elements have taken place during that time. Our 1908 observations seemed to be slightly greater positive than the velocities for 1907 for the corresponding phase. This may have been accidental, the difference being at most less than 2 km. If the absolute velocities of Deslandres' observations were known, it would decide whether the velocity of the system has been changing or not during these six years. If his two observations of the year 1901 are as they appear in his paper, we must conclude that the period has been changing during the interval. If we omit these two and use the remaining twenty-four of 1902 with our elements we get what appears on the face of it to be a much better agreement of the observations with the curve. There is one discrepancy. The observations fall short of the curve by a common amount, 1-5 days. The number of periods elapsed between the two epochs is in round numbers 1 - 5 125. By increasing the period T - or -012 days, this would be remedied, but while 125 this value of 17-124 days would not make much difference in Deslandres' observations, the least-square solution in our own shows it to be improbable. Here is a suggestion: Is it not probable that the presence of the third body will cause a rotation of the line of apsides similar to that caused by the sun and moon on the earth? A motion of the apse line in the direction of decreasing and at the uniform rate of x 360 or ll '112 0'2524 per period would account for this discrepancy. This motion, if it exists, 25a-p. 234 o 25a 234 REPORT OF THE CHIEF ASTRONOMER 235 SESSIONAL PAPER No. 25a would, in addition to decreasing to and consequently the slope of the curve near peri- astron, also cause the maximum positive velocity to increase and the maximum nega- tive velocity to decrease numerically. These questions seem to call for further work on the star at some future time. I do not think the data is sufficient at present to make any definite assertion regarding any change in the elementS>3them8elvesiio9Tiu^ B rtfiw ,ei- AJJ-I- 7 -KT^ - m & 8 '5?i/ B Hf^**A l 4 ktf -L-J. Additional N ^t^^fi^ r ^eg^n^QlJ^^r^nfiuon of me Orbit. Since the foregoing /w*fe completed, ^ort 7e *A. J., 27-2-1908. REPORT OF THE CHIEF ASTRONOMER 243 SESSIONAL PAPER No. 25a King and, using these, twenty-one observation equations of the form of Lehmann- Filhes were formed. They were then transformed into the following normal equa- tions, where for. sake of homogeneity these substitutions were made : x y z u oy dK A'.de 1000. "' (TT? K (1 - )t K dT. The normal equations are: 116 OOOx - 11-974?/ 4- 1'8302 54' 535 a - 14'444r 57-796; 4- 19'935i< - 2'354v - 20'565w 4- 6'260 = + 2-376i< - 13-460v - T2l2w - 28'055 = 2'404t< - 4-352v + 3'883w - 19'760 = 59-931w - 13-1040 - 62'528w - 4 '652 = 45 343?; + 14"515w + 40 '046 = 69-129w + 7-200 = The solution of these equations gave as corrections: Sy = - -02km. SK = + -43 " 8e = + -050 8 1 + 3-41 -0'08 3... 271'7 -4'90 1 -0'33 -0 26 4 15'5 + 7'25 6 +0'28 -0'08 5 333-0 -6 90 16 + 0'02 -0 56 6. 112 1 + 5'50 3 4-0-11 4-0-14 7 255'6 -3 40 1 + 39 -0 03 8... . 0'6 + 6 20 1 fl'50 -0-13 9 138 '3 + 3-90 1 4-0'45 -t-0'29 10.. 435-5 -6'20 5 -0'96 4-0-01 11.. 417 '7 -7'60 9 -0-98 -O'Ol 12.. 480'8 + 1-63 11 -0 21 4-0 03 13.. . . 463'G -0-30 3 fl'19 4-0-12 14... . * 0'9 46-00 3 4-1-25 -0-04 15... 48'1 +7'65 8 -1-17 + 02 16.. . . 111-4 + 6-60 9 4-1-16 4-0'02 17 161-9 + 2-80 3 4-1-02 O'OO 18... 169-5 -0-97 3 -2-23 o-oo 19.. 238-4 -3-60 7 0'70 -0'32 20... 276 '7 6'60 9 I 1 81 -0'02 21... 359-4 -7 '00 12 rO'49 -0 06 244 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 j The probable error of a plate as determined from the last two columns of the table, is d= 1-04 / 2 p giving the data of the plates and using the formula r= -6745 km. per second. The curve, Fig. 22, is plotted from the corrected elements given in the following table. These are considered close approximations to the true values until observations in all phases of the star have been secured with the three-prism spectro- graph when a final determination will be made: ELEMENTS OF ORBIT. Elements. Graphical. Corrected. Period P. 492 days. 495 3 days. Eccentricity c 0-25 0-300 Longitude of apse w. 300 298 '98 Half amplitude K. 7'8km. 8 23km. Velocity of system y -0'57 km. -0.60 km. Periastron passage 2*. J. D. 2417730 J. D. 2417729-48 Projection semi-major axis a sin i 53,474,000 km. DVV. . 186'1 122'7 o n O a o 25a-p. 244 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 245 APPENDIX B. THE SPECTEOSCOPIC BINAEY, a COEON^ BOEEALIS. J. B. CANNON. The star a Coronse Borealis (a = 15 h 30 m ; 8 = + 27 30, was discovered to be a binary by Hartmann from measures of six plates taken at Potsdam in 1902 and 1903.* It was under observation at this Observatory during the years 1907 and 1908. In all 103 plates were secured, 46 in 1907 and the remaining 57 in 1908 ; the instrument used being the single-prism spectroscope. This star belongs to the class la 2 in the Vogel classification. The spectrum shows the dark lines, Hp, Hy, Hs, He, the magnesium line A 4481, the iron line A 4549, the calcium line A 3934 and a few other very faint lines. The hydrogen lines are all very broad and diffuse and very difficult of accurate measurement. He is so diffuse that it has not been measured at all. The line A 4481 varies in character, in some plates well defined, in others diffuse. The line A 4549 is very faint and has only been measured in a very few cases. The line A 3934 is in general a fairly good line, being weighted about the same as Hy and H$. In the measurement of nearly every plate it was found that the lines A 4481 and A 4549 gave entirely different velocities from the H lines and E. It was decided therefore to consider only lift , Hy, H s and K in the first measurements and the elements determined in this treatment are from the considera- tion of these alone. The lines measured, together with the velocities per revolution of the micrometer screw (0-5 pitch), are given in Table I. TABLE I. LINES (MEASURED) IN a. COUON/E BOREALIS. Element. Wave-Length. Velocity per revolution. ... HIV Hydrogen 4861 527 1451 4340-634 1044 M 4101-890 868 cium 3933-825 749 These lines vary in quality and were weighted accordingly. The whole plate was then weighted, regard being had, first, to the appearance of the spectrum, and second and more particularly, to the number of lines measured and the agreement in the mea- surements. The velocities found were plotted successively and gave a period of between seventeen and eighteen days. Trials of several periods ranging between these, gave 17-35 as the most satisfactory. There were available measurements of three plates of 1902 and ten of 1903 taken at Potsdam*, and it was found that on plotting these with the observations obtained here that if the period were increased to 17-355 days, they would, with one exception, lie very close to the curve. Table II. contains *A. N., 163, 31, 1903. 246 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 the number of the plate, the Julian date, the phase computed from the time of perias- tron finally accepted, and period 17-355 days, the weight of the plate, the velocity and the residual between the observed velocity and that compiited from the corrected elements. In order to obtain observations in which the errors might be reduced and a curve drawn showing smaller residuals, the one hundred and three observations were com- bined into fourteen groups. Plates of both years were combined indiscriminately, those at nearly the same phase being grouped together. The weight of each plate (Table II.) was taken into account and the weighted mean of each group computed, with the mean phase. (Table III. contains the mean phase from T mean velocity, weight and residual of these normal places.) TABLE II. MEASURES OF a CORON.E BOREALIS. Plate No. Year. Julian Day. Phase. Wt. Velocity. Residual. 784 . 1907. 2,417,720-74 13-041 4 -40 + 12'5 790 725 '63 0-576 4 + 32 o- 794 725'75 0-696 3 + 44 -10- 800 . 727-72 2-666 3 + 17 + 17' 808 735-69 10-636 3 -37 + 15' 813 737 64 12-5*1 4 -30 + 3' 830 738'74 13-681 2 -26 o- 837 739 73 14-671 4 - 17 - 3'5 845 740-69 15-641 3 - 1 - 8' 850 f 741-69 16'641 4 +11 - 1-6 861.. 747 '67 5-266 2 + 17 - 4-5 869 748-64 6 236 4 + 9 - 4'5 880 752-65 W246 1 -41 + 20' 888 , 753 62 H'216 2 -27 - 3' 892 - 754-64 12-236 4 -28 + r 912 761-64 1-876 2 + 25 -13-5 917 762-64 2'876 3 +30 + 2'5 919 ! 765'65 5 '886 3 + 8 0' 927 ( 766'61 6 '846 3 - 5 + 4'5 936 767 '58 7-816 4 + 8 -15- 939 f 769-68 9-916 3 -29 -lo- 941 ( 770-64 10-876 1 -30 - 7" 944 773-62 13-851 2 -26 + 0'5 951 ... 775'62 15-851 3 -19 +J5' 956 777'67 0-546 3 + 32 o- 973 M 789-58 11-466 2 -16 - 9' 978 ' 791-54 14-421 3 -24 + 1'5 986 794-69 0'216 2 + 12 + 16- 1060 and 10GI . . . 839 '77 10'38'i 2 -25 + 4" 1006 800-69 6 216 2 -14 + 18' 1014 803-63 9-156 2 - 7 - 8'5 1017 810'63 16'161 1 -14 + 13' 1022 ' 811-66 17 151 I + 5 + 15' 1026 815-50 3-676 3 +30 4' 1032 825-57 13-741 2 -22 - 3-5 1037 831'67 2'486 2 + 3 - 0'5 1047 and 1048 837 '53 8 '356 3 -15 + 5' 1083 and 1084 850'56 4'016 4 +26 - 2'5 1393 1908. 2,418,010-92 8'186 3 - 5 + 0'5 1402 017'87 15'136 3 -17 + 1 1493 t( 047'80 IG'356 3 - 6 -15- 1571 and 1572 096'69 7'181 3 -15 + 12'5 1581 098'73 9'221 - 1 - 5 -10- 1601 M 105-71 16-201 3 + 7 + 5'5 1608 . .... 110-58 3 716 3 + 9 + 17' 1623 and 1624 115-69 8'831 4 -14 + r 1628 and 1629 117-64 10'776 3 -11 - 11-5 1638 and 1639 . . 119-66 12 796 4 -21 - 65 1646 and 1647 . . 120-68 13 '816 3 -21 - 45 1652 124-64 0-421 3 + 42 -11- 1656 and 1657 126 64 2'421 3 + 27 + 10 1655... M 129-70 5-481 3 + 12 - 1- REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a TABLE II. MEASURES OF n UOBON* BOREALIS Continued. 247 Plate No. Year. Julian Day. Phase. Wt. Vel lt>73 and 1674 1908. 2,418,131-62 7'401 4 1683 and 1684 133-57 9'351 3 1692 H 134-68 10 461 2 1697 and 1698 136 65 12-431 4 1711 138-68 14-461 4 1721 and 1722 147-54 5-966 6 1739 152-65 11-076 2 1748 and 1749 154 57 12-996 6 1764 .' 159-64 0-711 4 1773 and 1775 . . 161-60 2'671 7 1798 174-54 15-611 2 1809 ( 175-62 16-681 3 1816 and 1817 18^7 178-55 179-54 2-266 3-256 6 2 1836 181-61 5 326 4 1841 and 1842 182-54 6'256 7 1852 . 185-56 9-276 2 1861 188-53 12-246 4 1865 ( 189-56 13-276 1 1882 and 1883 199 54 5'901 8 1894, '95, '96 and '97 ... 1949, 1950 and 1951.... 1991 ! 204 50 247-45 278-42 10-861 1-746 15-861 10 6 1 Velocity. Residual. 3 -18 -29 -24 -17 -44 -36 +37 + 43 -16 - 3 +41 + 27 +10 + 8 -15 -30 -15 + 11 -21 + 46 + 8 - + 2- 7'5 3 5- + 7" + 20- + 8'5 - 3 - 8-5 + 6 + 13- - 4- + 2-5 + 2- - 3-5 - 0-5 + 3-5 -12' - 35 - 2- - 7-5 -20- TABLE III. NORMAL PLACES OF a CORON/E BOREAHS. No. Mean Phase. Mean Velocity. Wt. Residual. 1 12 656 - 29-77 6 + 2 '37 2 . . . 13'777 - 23-54 2 - 2'34 3 14-664 - 18-50 3 - 2'29 4 5 15-831 16 '723 5-77 + 5'00 2-5 1'5 - 36 + 6"22 6 0-556 + 34-63 4 2'17 7.. 2-302 + 37'14 6 - 0'71 8 3-559 + 24 33 3 + 2 '66 9 5'657 + 11-10 4 -- 2 '47 10. G'250 + 2 '41 4 + 1'46 11. . 7 '968 6'71 4 - 1'65 12... 9-444 - 17'27 2 + 0'31 13 . 10 517 - 22'21 3 + 0"25 14*. .... irooo - 24 35 3 + 0'75 From the radial velocity curve the elements of the orbit were determined by the graphic method of Dr. King.* These were: P =17-955 days T = J. D. 2,417,725-55 K = 33 km. e = -28 o> = 309 y = Okm. * Astro. Journal, Vol. XXVII. 248 9-10 EDWARD VII., A. 1910 To obtain elements which would give a curve more nearly suiting the normal places, a least-square solution was made. On the advice of Mr. Plaskett, the period 17-355 days was taken as fixed, and the fourteen observation equations (formed by the method of Lehmann-Filhes*) were determined without considering 8/j.. From these the following normal equations result: + 48* - 0-4500?/ + 3-7267.: + M799w + 2'81f>6t- -14" 1350- n = + 24'045l# - 7 2422z + 4420z< - '1050v - 4'1083-n = + 23-Ol08s - -2779w - -8737r + 3'9440-n = + 19-5267M + 17'5676r +63 4280- n = + 17'8291r +67 9099- n = Where x = 8y y = 8K z = K8e u = -K8o> V i / i O \ 3 (I - e-)t The solution of the above equations gave the corrections to the element: 8 y = + .635km. 8K = - -031 km. 8e = - -015 So, = - 3- 76 8T = - -449 days, and hence the following new elements: y = + -635km. K= 32- 969 km. e = -265 to = 305 -24 T = 2,417,725-101 J. D. P = 17-355 days. An ephejneris computed with these elements reduces the value of ^pvv from 498-94 to 217-35, but the differences found between these residuals and the observation equa- tion residuals were in some cases rather large, and at a suggestion by Mr. Harper whom I owe much for other valuable suggestions as well a second solution was made. This time K was omitted owing to the small correction obtained in the first solution, and the new observation equations contain only four unknowns, and hence only four normal equations follow: 48x + 2'0615# -f 1-11495 + 2'0989w +6'1200-n = + 24'8703y + -27503 + '3566u -9'4127-n = + 19-72842 +18'666H -5 8754- n = + 19-2174w - 4-4691 -n = in which x = 8y y = z = - E8 - 316 ; Comparing these with the corresponding elements from the other lines, the main differ- j ences are seen to be in the values of y and e. In the work which has been done on the radial velocities of stars other than binary, j some stars have been found, certain of whose lines gave consistently different veloci- j ties from other lines. Among them is o Ceti, the emission and absorption lines giving i a considerable difference in the value of the radial velocity; so with nearly all Novae. ! Nova Aurigse has been discussed at some length by several astronomers and a similar phenomenon has been noted. Explanations have been suggested as to the cause of the different displacement of different lines. These consist chiefly of two, first, a lagging envelope producing the lines of less displacement towards the red end of the spectrum, and second, an ever-expanding envelope coming from a continuously productive source. How far such conditions would go to explain a state of affairs such as we find in a Coronse, it is difficult to say. We may also look upon the system as receding with a velocity of 6-69 km. per second the velocity given by the magnesium line and con- stantly expelling hydrogen and calcium vapors, the velocity of expulsion affected by the periodic recurrence of physical conditions, brought about by the changing relative positions of the stars in the orbit, which conditions fail to influence magnesium in any way so far as changes in the lines are concerned. This is quite plausible, for in 250 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 the spectroscopic study of the Sun's surface, regions have bei'ii found, such as .sun- spots, the spectra of which show certain lines considerably affected in character and position, while other lines denoting other elements remain unchanged. After the first part of this work had been completed, Mr. Jordan issued from the Allegheny Observatory his publication on the Orbit of a Coronse Borealis. Comparing his results with those obtained here from the lines H 1, Hy, HS and K, it was seen that, although on the whole they agreed fairly well, there was considerable difference in the values of e. This is largely due no doubt to the fact that Mr. Jordan used the line (Mg) A 4481, together with the above lines in the determination of his elements. However, the fact that the plates we obtained here were measured by several men and all agreed that the Mg line gave large discrepancies seems to justify the separate treatment. The accompanying curves represent Fig. 23, the hydrogen and calcium curve, and Fig. 24 the curve from the hydrogen and calcium lines, and that from th.e mag- nesium lines. "7 * co S S + + + + S 8 i i 25a-p. 250 REPORT OF THE CHIEF ASTRONOMER 251 SESSIONAL PAPER No. 25a APPENDIX C. THE TWENTY-THREE FOOT SOLAR SPECTROGRAPII. RALPH E. DELURY. This instrument is adapted for analyzing with great dispersion the light of the sun and of laboratory sources, such as the electric spark, arc, flame, &c., and is prim- arily intended for investigating the conditions in the sun. It is situated in the base- ment of the Observatory in the Solar Research Room, which is connected on the north side by a cement tunnel to the louvred passage of the Coelostat House from which the image of the sun is directed to the spectrograph, and on the east side to the Chemi- cal Laboratory, which is used also as a photographic dark-room in which are developed the photographs of the spectra taken in the spectrograph. The spectrograph may be described under the following heads: (a) Optical Parts; (&) Mountings; (c) Slit- Attachment; (d) Camera and Plate- Holders ; (e) Guide-plate for the Sun's Image. (a) Optical Parts. The optical parts are: a slit with metal jaws 1-3 in. (3-4cm.) long, mounted so as to leave 1 in. (2 -5 cm.) clear, and provided with a micrometer, for adjusting the width of the slit, reading to thousandths of an inch; a six-inch (15cm.) collimating lens of 22 ft. 10 in. (695 -5 cm.) focal length for yellow light; and one of the earlier Michelson plane gratings of speculum metal having a 4-25 in. by 4-75 in. (10-8 cm. by 12cm.) surface ruled 12,700 lines to 1 in. (500 lines to 1mm.). These parts are arranged after the plan described by 0. Von Littrow in 1863 (see Kayser Handbuch iler Spectroscopie 1, 513). In this arrangement the slit is placed at (or near) the focus of the lens and the dispersing system (in this case the grating) is placed on the other side of the lens in such a manner that the dispersed light returns through the lens which focuses it near the slit, as illustrated in Fig. 25, which represents a vertical section through the middle of the spectrograph and mountings. 8 is the slit, L the lens, placed at its focal distance from the slit arid G is the reflecting grating placed just behind the lens L, and tilted so that its ruled lines are parallel to the slit. The beam of light to be examined passes through S spreading out to fill L, which renders it, parallel before it reaches G, which disperses it and reflects or diffracts it back through L. By tilting the top of the grating slightly towards the slit the diffracted light is made to pass back through the lens which focuses it below the slit where it may be examined with an eye-piece or photographed in the plate-holder ((7). By rotating G about a vertical axis on either side of the normal, the different parts of the different orders of spectra are diffracted back through the lens L, and by sliding the lens for- ward I'll- backward the light of the different wave-lengths may be focussed sharply at C. * (Ij) Mountings. The two tilting- movements of the grating mentioned in (a) were provided in the cell of the grating by the John A. Brashear Co., from whom it was purchased. The forward tilt is given by screw J and suitable springs pressing against the back of the grating; and a screw placed on the side gives the means for ad- justing the lines of the grating parallel to the slit. The grating in the cell rests on the stand G', the axis of which fits into a cylindrical socket in the bottom of 252 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 the end, B, of the spectrograph, and by turning a handle K" (Fig. 26), attached to a worm which works in the toothed sector, K, which is attached rigidly to the axis of G', the grating may be rotated about this axis which passes through the centre of the plane of the grating, thus reflecting any desired part of the spectrum of any order through the lens to C. By means of the vernier-pointer, V, readings to tenths of a degree may be made 011 the graduated arc E and a record of these readings with the corresponding wave-lengths of the spectra reflected to G is kept, so that by turning K" until V points to the proper angle, any desired wave-length may be reflected to the centre of C and the grating may be clamped in this position by tightening the screw- clamp K'. The lens may be shifted and clamped at any focus by means of the handle H, and the position of the pointer F is read on a millimetre scale attached to the bottom of B, as shown in Fig. 26. Ordinarily the side represented in Fig. 26 is facing downwards and a mirror is placed below the scale and the arc so that the reading may be made conveniently. In addition to these movements of the grating and lens, the mountings permit of rotation of the spectrograph as a whole about its axis, i.e., about the line joining the centre of the slit and the centre of the lens. This idea was sug- gested by Mr. Plaskett (Report Chief Astronomer for the year ending March 31, 1907 r p. 58) and employed by Newall (Monthly Notices 68, 7, Nov., 1907), and used also in the spectrograph mounted vertically and used with the vertical telescope of the Mount Wilson Solar Observatory. It facilitates the study of the rotation of the sun, by enabling the observer to reflect the limbs of the sun at opposite ends of any diameter always tangentially to the slit, as described in detail under (c), in Fig. 25, A and B are the two ends resting on the supports A! and B' which rest on the cement piers P and P' built on the cement floor. The end A is of half-inch cast brass. It has a V- groove running around its circular rim into which the semi-circular cast-iron support A' is bevelled to fit. The back, of A is a rectangular box 3 in. by 11 in. by 14 in., over which the wooden box is tightly screwed and clamped. The axis of B, which is of cast-iron, rests in a cylindrical bearing in the brass support B'. The box on B pro- jects 3 in. on top and 16 in. on the sides and bottom to give good support for the lens and grating and to provide a surface to which the box is screwed tightly. The bot- tom of B is milled smooth to give easy bearings for the grating and lens mountings- The box is painted black on the inside and is provided with diaphragms, M, to pre- vent as much as possible the diffused light reflected from the lens and grating from striking the photographic plate in the holder, C. There is a hinged door, D, just above the grating and lens so that these may be conveniently reached. The spectrograph thus rests at its two ends on the supports A' and B' on which it may be rotated about its axis. The rim of A is toothed (T, Fig. 25) and into these teeth fits a gear attached to T* (Fig. 27), which is supported in A' and which may be turned by means of the handle T f (Figs. 27 and 28). The circular face of A is gradu- ated in degrees and by means of the vernier attached to A' the angle may be read to tenths of degrees. This is necessary in determining the ' East and West ' line by allowing the image of the sun to drift across the face of A tangentially to some arbi- trary line on A. From this angle read on the vernier, the position of the diameter of the sun's. disc which lies in the plane of the sun's equator, is easily found since the inclination of these two lines to each other at any time is known, and hence the arbi- trary line on A may be made parallel to any required diameter of the sun's image. The mountings were constructed by the Victoria Foundry Co. from designs mad.? in accordance with the suggestions of Mr. Plaskett who supervised the construction of the spectrograph. The mechanisms for rotating the grating and the spectrograph were skillfully constructed by Messrs. Mackay and Lucas. (c) Slit-Attachment. The slit-attachment is shown in Fig. 27. It was designed by Mr. Plaskett and made by the John A. Brashear Co., a, ~b, c, d are 45 reflecting prisms mounted on 25a p. 252 REPORT OF THE CHIEF ASTRONOMER 253 SESSIONAL PAPER No. 25a brass plates which are supplied with racks and pinions e, e, e. When the sun's image is placed concentric with the circular front of the spectrograph, the prism d is moved to take the light from any desired point near the sun's east limb and reflects it to the prism c, which directs it down through the slit to the lens and grating. In a similar way the larger prism, a, reflects to the west limb through the prism b f whose tapering ends form a V-shaped space into which the tapering end of c fits closely, so that the spectrum from the east limb is placed closely between two strips of the spectrum from the west limb. The widths of these strips may be varied by moving the plate holding the prisms & and c back and forth, and by means of two little slides placed directly over the ends of the slit. When desired the shutter, f, may be used to keep the light passing through the slit from reaching the lens. In place of the plate bearing the prisms & and c, the attachment, h, may be used and by means of two adjustable screws which serve as stops between which it may be shifted so that two spectra of any desired widths may be taken in succession, the one being placed between two strips of the other, the V-shaped openings and the V-shaped slides providing the means for adjusting the widths of the strips. The prism arrangement is intended for obtaining plates for measuring the rotation of the sun or for any inves- tigations where it is desirable to take the spectra simultaneously, while the attachment, h, is designed for taking spectra in succession, and of course the time of an exposure will be less in using it than in using the prisms which diminish the intensity of the light considerably. (d) Camera and Plate-holders. The plate-holders are made to take a 2-5 in. x 12 in. plate, a hinged back with three springs pressing the back of the plate at its edges holding the plate firmly in place without danger of bending it. The plate-holder, C, Fig. 28, is slid into the frame C', Fig. 27, and clamped, as shown in Fig. 28. _The frame C' can be raised or lowered by rack and pinion as shown, so that several strips of spectra may be put side by side on the same plate, and spaced as desired by reference to the millimetre scale on the right hand side. The plate-holder fits over a 1-5 in. opening in A, Fig. 27. The frame C" may be tilted slightly so that the plane of the photographic plate may be made to follow more closely the focal surface of the lens. (e) Guide-plate for the Sun's Image. In Fig. 28 is shown the guide-plate R, screwed tightly over the slit-attachment. R has a number of concentric circles and a diameter scratched on its surface and blackened so as to be easily visible. These circles are concentric with the circular front of the end-piece A. The figure shows the sun's image placed concentric with these circles. At each end of the diameter of these circles is a small rectangular open- ing, back of which is a little slotted silver-plated shutter which runs in bevelled slides. These shutters may be adjusted by means of the millimetre scales on the edges of the two rectangular openings, so that the slots are tangential to the same circle whose diameter is read off directly, the distance between the nearest ends of the rectangular openings being 200 mm. In the same manner the diameter of the solar image is mea- sured. Back of these slots the prisms are adjusted to give the maximum brightness in the light reflected from the grating, and thus the spectrum from a point in the image near one limit may be placed between two strips of the spectrum from a part of the image at the other end of the diameter. To get any desired latitude on the sun's disc, the image is allowed to drift across the guide-plate tangentially to the diameter the arbitrary line mentioned above scratched on the plate and the vernier reading taken of the angle corresponding to this ' east and west line ' which makes a known angle at any time with the sun's equator. The handle T" is then turned to place the diameter in the desired position. One slit will thus be placed at a certain latitude north of the 254 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 sun's equator and the other at the same latitude south of the equator, and the displace- ment of the spectral lines resulting therefrom will give a measure of the rotation of the sun in this latitude by turning T" so that the slits are placed at the same latitude, but on the opposite sides of the equator to those of the former position the same dis- placement should result if: (1) the sun's equator has been accurately determined, (2) the image in both cases is concentric with the circles on the guide-plate, and (3) the rotation of the sun is the same for the same latitude in both hemispheres. Taking the mean of the two measures from plates taken in succession would eliminate most of the errors introduced. SOME RESULTS. The spectrograph was mounted in August, 1908. The cement piers, P, P' (Figs. 26, 27, 28), are made so as to make the axis of the spectrograph coincident with the axis of the concave mirror in the coelostat house, when the image from it is placed in the middle of the face, A, of the spectrograph, P being a few inches higher than P', giving the proper inclination (about 3^). The spectrograph was adjusted and numerous test photographs were taken in the various parts from A 3800 to A 6000. To keep the light reflected back from the surfaces of the lenses from striking the photographic plate the ordinary method of putting a strip across the lens, parallel to the plate, was tried; also, in some tests, the lens was tilted forward so as to throw the reflected light below the photographic plate. This latter method does not alter the character of the lines very much and possesses the advantage of doing away with the strip which masks the central part of the grating and lens. It was soon found that the character of the spectral lines in the different orders from either the left or right inclinations of the grating was not as good as desired. By directly reflected light the grating appears to have three areas of different reflecting powers and it was found that the spectra from these areas did not harmonize. The best spectra were obtained by masking the two smaller areas and using the remaining strip which constituted the right three-fifths of the grating. Even from this part of the grating the spectral lines are poor. In the first and second orders the spectra from the grating tilted to the right are much more intense than those obtained when the grating is tilted to the left, while the reverse is the case in the third order, and furthermore the lines are sharper when the grating- is tilted to the left. Consequently the rotation plates obtained were made with the grating tilted to the left and the left two-fifths of the grating masked together with the central strip placed over the face of the lens to cut off the reflected light. The focal curves, for left and right inclinations of the grating were obtained in the first three and part of the fourth orders, for the whole grating with the central strip masked. These are plotted in Fig. 29, the dotted lines being the photographically determined curves and the continuous lines, those visually determined. It will be seen that the locus of the foci for any wave-length in the different orders, instead of being a straight line of constant focus, is a curve (nearly a straight line) of varying focus. This is very likely due to the character of the reflecting surfaces between the scratches on the grating, for it may be assumed that the diamond scratching-point distorted the strips between the scratches in such a way as to make one side of the surface slightly convex and the other slightly concave, as might easily happen since on one aide of the diamond-point the speculum is scratched or furrowed, while on the other side it is not. At any rate the grating is not what it should be for the work planned for this spec- trograph. This work must necessarily deal with the exact positions and character of the spectral lines and any large or small changes in these. It is chiefly the minute changes that are of interest at present in solar investigations, and the very best possi- ble definition of the spectrum lines is required for a satisfactory measurement of these changes. It is hoped that a new grating of first quality may soon be secured, as such is necessary to yield satisfactory results. Everything else is now in readiness for the careful study of solar problems. 25a p. 254 REPORT OF THE CHIEF ASTRONOMER 255 SESSIONAL PAPER No. 25a In addition to rotation-plates, plates of the sun spot spectra were obtained when- Wer the conditions were suitable. Samples of both are shown in Fig. 30. In the .following table the measurements of a sample rotation-plate (L 413) are given. In taking these plates long exposures (10 or 12 minutes in the third order near 4300) were necessary owing to the fact that a very small area of the grating was used. Dur- ing this interval the sun's image would become blurred and distorted, thus allowing light from different points on the sun's surface to pass through the slits. The poor values in the following table are probably partially due to this cause and partially also to aberrations produced by some of the curious properties of the grating and to the very poorly defined lines produced. Many of the lines were so poor that measurements of them were not made and many of the finer lines were spread out and weakened so as to be almost invisible. It is hoped that the new grating will remedy these defects. Measurements of plate L 413, 0-0, slits 226mm. apart, diameter of the sun 232 mm. : x Mean of 5 mm. readings middle strip Mean of 5 mm. readings lower strip. Mean of 5 mm. readings upper strip. Mean difference. 25\ Velocity km. per sec. 4136-678 2-9828 3-0314 3-0430 0-0544 0-0488 1-77 4137-156 3-5233 3-5650 3-5931 557 499 1-81 4140-089 G'7876 6-8342 6-8411 500 448 1-62 4147-836 15-4109 15-4623 15-4711 558 500 1-81 4149-533 17 2990 17-3517 17-3520 529 474 1-71 4150-411 18-2771 18-3256 18-3411 513 460 1-66 4154-071 22-5768 22-6215 22-6324 502 450 1-62 4154-667 23-0205 23-0724 23-0828 571 512 1 85 4154-976 23-3789 23-4309 23 4333 532 477 1-72 4157-948 26-6898 26-7408 26-7492 452 405 1-46 4157-948 . 26-6868 26 7431 26-7558 627 562 2-03 4158-959 27-8144 27 8550 27-8718 490 439 1-58 4163-818 33 2268 33-2824 33-2919 604 542 1-95 4169-110 39-1097 39-1550 39-1763 560 502 1-81 4171-068 41-2803 41-3317 41-3462 587 526 1-89 4174-095 44-6767 44-7188 44-7331 489 438 1-57 4175-806 46-6005 46-6480 46-6549 510 457 1-64 4176-739 47-6361 47-6780 47-6990 524 470 1-69 4179-025 50-1899 50 2346 50-2450 499 447 1'60 4179-025 50 1928 50-2358 50-2405 454 407 1-47 4181-919 53-4269 53-4799 53-4878 571 512 1 84 4182-548 54-1376 54-1827 54-1958 517 463 1 66 4187'04 59-3360 59-3872 59-3987 570 511 1 83 4187-943 60-1723 60-2212 60-2388 577 517 1-85 4187-943 60-1754 60-2208 60-2423 562 504 1-81 4196-372 69-5688 69-6076 69-6247 474 425 1-52 4199-267 | 72-7938 72 8540 72-8663 664 596 2-13 4199-267 72-8065 72-8626 72-8720 608 545 1-95 4201-089 74-8526 74-9020 74 9137 553 496 1-77 4202 '919 76-8960 76-9398 76-9492 485 434 1-55 4203-730 77-8073 77-8667 77-8677 599 537 1-92 4204-622 78-7510 78-8003 78-8116 550 493 1-76 4207-291 81-7826 81-8279 81-8413 520 466 1-66 4208-766 83-4393 83-4904 83-4972 545 488 1-74 4213-812 89-0824 89-1385 89 1469 601 539 1-92 4216-351 91-9078 91-9656 91-9685 593 532 1-89 4220-509 96-5671 96-6150 96-6305 557 499 1-77 4233 328 110 4159 110 4651 110-4745 539 483 1-71 4236 112 113-1064 113-1574 113-1659 553 496 1 76 4236-279 113-2910 113 3460 113-3567 604 542 1-92 4230-279 113-2911 113-3482 113-3563 612 549 1 94 4238-970 116-3636 116-4092 116-4177 499 447 1-58 4246-966 126-2158 126-2723 126-2819 613 550 1 94 4258-774 139-0965 139 1464 139-1514 524 470 1-66 4265-418 147-6064 147-6630 147-6666 584 524 1-84 4268 915 150-7909 150-8440 150-8464 543 487 1-71 4271-325 153-4834 153 5426 153-5454 606 544 1 91 4271-934 154-6638 154-7190 154-7275 595 533 1-87 25o19 256 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1913i Measurements of Plate L 413 (Continued). X Mean of 5 mm. readings middle strip Mean of 5 mm. readings lower strip Mean of 5 mm. readings upper strip. Mean difference. 25X Velocity km. per sec. 4274-958 157-5662 157-6159 157 6230 0-0533 0-0478 1-68 4279-643 162-8316 162-8856 162-8923 574 515 1-81 4282-565 166-1090 166-1575 166-1650 523 469 1-64 4283-169 166-7867 166-8456 166-8437 580 520 1-82 4287-566 171 7201 171-7671 171-7684 477 427 1-49 4288-310 172-5555 172-6182 172-6188 630 565 1-98 4289-525 173-9153 173-9697 173 9714 553 496 1-73 4289-885 174-3185 174-3698 174-3829 579 519 1-82 4290-080 174-8803 174-9256 174-9400 525 475 1-66 4390-377 175-0671 175-1189 175-1266 557 499 1-74 4291-114 176-2785 176-3263 176-3375 534 479 1'67 4295-383 181-0754 181-1309 181-1437 619 555 1-94 4300-211 185-9150 185-9642 185-9754 548 491 1 71 4300-211 184 -701.1 184-7533 184-7603 557 499 1-74 4302 692 187-4850 187-5400 187-5453 577 517 1'80 4312 462 200-4632 200-5002 200-5203 571 512 1-78 4316-962 205 6104 205-6557 205 6737 543 487 1-69 4320-907 207-9588 207-9978 207 0193 498 446 1-55 4321-119 208-1885 208-2350 208-2553 567 508 1-76 4331-811 220-2219 220-2719 220-2817 549 492 1-71 4337-216 226 3078 226 3617 226-3729 595 533 1-85 4338-084 227 2934 227-3348 227-3580 530 475 1-64 4338-430 227-6796 227-7315 227-7403 563 505 1-75 4339-617 229-0152 229 0619 229-0751 533 478 1-65 4339 882 229-3068 229-3559 229-3787 605 542 1-87 4343 861 233-7958 233-8477 233-8647 604 542 1-87 4344-451 234-4621 234-5066 234-5309 567 508 1-74 4344-670 234-7022 234-7509 23f7669 567 508 1 75 4344 670 234-7023 234-7510 234-7679 572 513 1-77 4351-216 242-0735 242-1259 242-1400 595 533 1-84 4351-216 242-0719 242-1223 242-1343 564 506 1-74 Mean .... 1-77 The scale, which is practically constant over the whole plate, is 1 A. U. = 141 , mean difference . S\ /Tr , .. , ,. ,,,. mm., hence 2&\ = . The velocity is - - (Velocity of light) 1415 A 299860 km. per second. Heliographic latitude of the centre of the sun's disc wf A 6 26' when plate L 413 was taken, consequently the velocity at the equator, as detei 232 1 mined by this plate is ~ 1-77 = 1-83 km. per second. This value is th 226 cos 6 26 linear velocity of the sun's limit at the equator, as measured, and will evidently giv the synodic period of the rotation, the value for which is 1-86, as given by Adams. T reduce to the sidereal period requires the addition of 044km., making the velocit l-97km. The generally accepted value is approximately 2-05km. per second, ami th deficiency in the present case may be safely ascribed to errors introduced by the grating REPORT OF THE CHIEF ASTRONOMER [SSIONAL PAPER No. 25a 257 APPENDIX D. j OUBLE STAR MEASURES. PHOTOGRAPHS OF COMET MOREHOUSE. OCCULTATIONS OF STARS BY THE MOON. FIELD INSTRUMENTS. ABERRATIONS OF THE STELLAR CAMERA OBJECTIVE. R. M. MOTHER WELL. DOUBLE STAR MEASURES. Three half nights each week have been devoted to micrometer and photographic i>rk, including the series of tests made on the camera objective. Micrometer work Is consisted principally of the determination of the position angles and distances of 5ual double stars, the working list being prepared from Burnham's Catalogue of juble Stars. An endeavour is being made to measure only those which have not been insured for some time or whose motion is such as to require frequent measurements. The fllar micrometer used, is the Warner and Swasey type, and it has been found ither unsatisfactory in the determination of position angles owing to there being no rick-motion screw for moving the position circle. A self -registering attachment wld be a great improvement as the present arrangement requires the frequent use of ihand-lamp which dazzles the eye. Considerable difficulty has also been experienced i keeping the eye-piece clear of frost in the winter, each setting of the micrometer- lad or position-circle requiring several clearings of the glass. Following are the measures made during the past year, each measure being the i?an of eight settings for position angle and four double-distance measures : , Star No. Date. Position Angle. Distance. Star No. Date. Position Angle. Distance. 151... 1908'786 279 1'34 7117... 1908-464 298-2 Cloudy. 269.. 1908 765 113'9 5'78 7318 1908-317 184-3 3'81 1427.... 1908-921 313'9 3'28 1908-575 186'8 4'01 1750.. 1908-921 249 '1 17 "24 7429 "5 1909-429 252'9 9 39 2040.. 1908-921 218 '8 4'21 7450. 1908'575 15'2 8'70 2043.... 1908-921 328'5 1908-617 14 3 9-21 2536.... 1908'996 305'3 2 73 1908 631 14'0 9 53 3398.... 1908-996 6'4 1909-412 14-9 8-91 4452 1909 341 43 3 2'60 1909-429 13 9 9 32 4530... . . 1909-086 139 '6 6'12 7451 1908-317 255'4 16 64 4890 1908-247 196' 5'14 1908 ' 464 254-1 17 11 1909'086 196 7 4'88 1908-575 254'8 16'57 1909-303 197'0 5'11 1908-617 256-0 16 17 5011.. 1908'247 45 '5 1'88 1908-631 254'6 16 "65 5014.. 1909'202 235-9 3'50 7458 . 1908' 575 288'9 3 24 1909-303 234 3-39 7<>04 . 1908 464 211-9 17-12 1909 841 235 5 3'40 1908-497 211 9 16 89 5125... 1908-304 146 5 3-43 1908-575 214 16 59 5319.. 1908-304 176'9 2'50 7642. 1908-575 89 8 1'77 1908'426 177-3 2 "78 7915 1908'439 18'2 5-03 5337 1908'977 295 '2 30 '78 1903-492 20 5 38 1909-183 294 4 31 50 1908-617 18 4 5'48 1909 -202 294 "8 31 ' 89 5388 1!K)8 247 117-4 3'88 1909-399 294 3 31 "Oil 1908 426 115 5 3 43 6780.. 1909-183 353-4 T 1909-303 106-7 6'57 1908-522 138'0 3'7i 6035 1909-078 178-9 16 32 1908'575 138 '3 1909-086 181-7 16-10 1908'581 138 '6 4'0 1909-183 179-3 16-50 1908 613 137 '8 3-9 1909-399 179-4 16-41 9905. 1908 600 271 '1 6211 1908-426 359-2 2'60 9969 1908 " 600 155-7 Cloud 6386 1909-360 119-0 2'99 9977. 1908 '641 170 1 4-1 7927 1908-617 127-0 33-08 1908 '765 171 '0 43 1908-631 125 3 33'24 1908 ' 786 171 "8 3-5! 1909-429 126-5 33-21 10061. 1908 ' 765 185 '3 7"! 7930 1908 '617 ISO'S 24'94 10072 1908 "613 9 12'2 1908-631 180-5 24'93 10305. 1908'522 74 '2 8003 1908-309 312-4 4'15 10385 1908 '581 lll'O 3-51 1908-445 313'3 4'17 10685 1908 ' 522 164 '6 1*8 8082 1908-309 22'8 8'11 10709 1908'C13 158 '3 3 P S 1908-426 22'6 7'98 10742. 1908 '613 349 '2 22"9' 1908-439 25'4 7'91 1908 ' 765 351 '5 t >3'8 ! 1908-445 24'4 7-95 10773 1908 '522 309 "3 3'3' 8303 1908-309 258-5 2'67 1908' 5 U 307 ' 9 1908-445 258 '7 1908 ' 581 307'5 3'7i 1908-617 259 '7 2-53 1908 78(5 307 "8 3-4' 8364 1908-617 81 '6 2'71 1908 ' 805 308 '8 til 1908-746 78'2 2-8^ 10901 1908 '013 112'6 K-fi; 1908-765 79-4 2'70 1908 ' (541 112'0 5-fi! 1909-429 78'2 3 00 12043 1908 ' 765 34 3 5'9' 8384. . . 1908-624 79'0 1'49 12753 1%8 ' 765 160 '1 3'0 8404 1908-631 338 '4 27 '15 COMET 1908c (MOREHOUSE). This comet was visible for over three months, but dense smoke and umisua!' cloudy weather prevented any attempt at obtaining an extensive series of photograpl Single exposures were made on seven different nights, with the Brashear DoubJ attached to the equatorial telescope. A filar micrometer was used in guiding and \v very satisfactory in preventing drifting but, owing to the smallness of its field, d not permit of the head of the comet being shifted appreciably from the centre of t camera field. Had it been possible to so shift the head, more of the tail would ha been included in the photograph. The following table gives the date and duration of each exposure : Plate. Eastern Standard Time. Beginning of Exposure. Duration. Remarks. 31.. 1908. h m 6 45 6 10 7 25 7 15 6 15 5 30 h 1 1 1 1 m 5 55 55 o 25 Very smoky. Clear . Clear but unstead; Very clear. Clear, high wind. 32 it 19 33 H 31 34 November 1 35 ii 13 36 it 26 PLASKETT ASTROPHYSICS. 25a p. 258 FIG. 31 & 32 Morehouse's Comet. PLASKETT ASTROPHYSICS. FIG. 33 & 34 Morehouse's Comet. PLASKETT ASTROPHYSICS. 25a-p. 258 FIG. 35 & 36 Morehouse's Comet. REPORT OF THE CHIEF ASTRONOMER 259 SESSIONAL PAPER No. 25a An exposure of one hour was made on October 20, but the smoke was too dense. In the course of the exposure the head of the comet passed over an eighth magnitude :star without perceptibly dimming it. Fig. 31. The dense smoke accounts for the faintness of this photograph, but still it is the most interesting one of the set, on account of the knots in the tail about one and a half degrees from the head. This portion seems to have separated from the head and drifted off while new matter has been given out. There has also probably been a motion southward on the part of this detached mass, greater than that of the comet as the new matter in the tail connects with the north side of the knots, while the south- ern part is altogether clear of the tail. The curved form of the central and southern portions of the detached mass is also worthy of notice. The new matter is connected to the head by a narrow neck and on either side rays extend back about 0-5 degrees. Fig. 32. This photograph is even more faint than Fig. 31, but the head shows con- siderable detail. The new portion of the tail spoken of in Fig. 31 has apparently been forced back by the rays on either side, they being joined together now just back of the head. Although only three days have elapsed between these exposures we can readily see that, during this interval, the comet has been very active internally. Figs. 33 and 34 indicate a continuation of this activity. Fig. 33 shows several : distinct knots in the tail about one to one and a half degrees from the head. Beyond these the tail gradually widens out, being uniform on the north side but broken on the south side. Fig. 34, one day later, shows the same knots farther away from the head and more diffused. They seem to have been separated from the nucleus, the bright por- tion next to the head in Fig. 33 broadening out here into a fan-shaped tail. Beyond the knots the tail has widened slightly. Fig. 35 shows a very bright tail extending out about two degrees with short rays on both sides of the head. As in Fig. 33 the north side of the tail is uniform, while 'the south side shows several offshoots. The comet was apparently in a very active state at this time, but thirteen days elapsed before I had an opportunity for another exposure, and Fig. 36 shows a much fainter and divided tail. Evidently the activity has become much less, the faintness of the tail being partly due to its division into 'two parts, but more particularly to a change in the conditions governing the state of the comet's head. Are these changes in appearance due to some internal state or are they due to changes in the surrounding medium? While this set of photographs can lay no claim to completeness, it demonstrates clearly the necessity for frequent exposures at as close intervals as possible if we wish to know with any degree of accuracy the changes actually taking place. It also shows that these exposures should not be too long, otherwise one plate might be a combina- | tion of several phases. No other comets were visible here in 1908, but several exposures were made toward the close of the year in search of Halley's comet. The end of July or the early part of August, 1909, should see the discovery of this famous celestial visitor. Photo- graphy will doubtless first reveal its presence and on account of this it is desirable that the stellar camera should be available for work every night. With the present mount- ing of the camera this means the suspending of all work with the equatorial at such times when the comet may be observed. This is much to be regretted as both the j equatorial telescope and the camera are excellent instruments, and it is hoped that a : separate mounting may be provided for the camera at an early date. Halley's comet will not return for.at least seventy-five years, but every year brings with it new comets; so if our Dominion Observatory is to take a foremost place in the discovery and study of these strange visitors, the equipment necessary for camera work should be provided at once. OCCULTATIONS OF STARS BY THE MOON. The observations of occupations have been made mostly with the 15-inch equa- torial telescope as its superior mounting and clock-work render it much more satisfac- 260 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 I tory than the 4J-inch Cooke telescope. Predictions have been made by the graphical ! method of Wm. F. Rigge, but less than 10 per cent of the predicted oecultations were observed owing to cloudy weather. Following are the observations: OCCULTATIONS OF STARS BY THE MOON. Date. Phenomenon. Star. Limb. G.M. Time of observation. 1908. April 9 Disappearance 17 Cancri Dark h. 6 7 8 13 11 12 16 5 12 16 17 16 17 16 17 m. 53 2 8 41 28 52 30 19 35 25 35 24 12 30 s. 53 2 55'6 36 5 23-3 11-1 16-8 41'0 1'8 15-8 6-1 37'8 59'7 50'0 31 57-4 ,,13 June 11.. Reappearance. Disappearance Bright o 1 Librae Dark M 12 v* Scorpii October 13. Reappearance. ... Disappearance Bright. . . n Tauri November 1. y Capricorni Dark 1909. y Cancri Bright March 12 Reappearance /3 1 Scorpii March 14 Dark Disappearance 565 Scorpii. Bright. Reappearance Dark Disappearance Reappearance 63 Ophiuchi Bright Dark INSTRUMENTS USED ON THE BOUNDARY AND GEODETIC SURVEYS. The instruments used on these surveys have all been carefully catalogued and' stamped, an index system being used which shows the office number, description of instrument, price, date of receival, name of maker, location and disposal of each instru- ment. A separate account is also kept of the instruments as taken out by each party in the spring, so that each man can readily see what instruments he is held responsible for. Following is a list of the principal instruments used during the season of 1908 : Name of Instrument. Number Used. Name of Instrument. Number Used. Barometers 20 Heliotropes 8 Balances 5 Levels 11 Binoculars 18 Plane Tables 5 Cameras 18 Sextants 2 Chronometers 14 Tapes.. 25 Clinometers 4 Telescopes it Compasses 25 Transits 47 ABERRATION OP THE STELLAR CAMERA OBJECTIVE. The stellar camera used in the Dominion Observatory, Ottawa, for photographing star clusters, nebulae, comets, or any other celestial objects covering a wide field, is fitted with a Brashear photographic doublet of 203mm. aperture and 1060 -3mm. focus. The camera tube (Fig. 37) is bolted to the telescope tube opposite to its place of attachment to the declination axis. This method of mounting is rather unsatisfactory, however, as the telescope tube intercepts a large portion of the light on the west side of the plate. The effective field has a diameter of about 11 20', so the camera is well adapted in this respect to its work. The tube containing the objective is nickelled and moves freely in the main metal tube, the position of focus being adjusted by a rack and pinion with a clamp screw to hold it in the required position. This position is read on PLASKETT A STROPHYSICS. FIG. 37 Stellar Camera. 25a p. 260 REPORT OF THE CHIEF ASTRONOMER 261 SESSIONAL PAPER No. 25a a millimetre scale. A metal shutter covers the objective and the plates are held in a metal frame fitted with springs. When accurate guiding is required the micrometer wires in the telescope are used, the great focal length of the refractor, as compared with the camera, rendering the guiding a simple matter. The following description of the lens is given by Dr. Brashear : ' The general construction is that which was first found by Petzval years ago, and has proven itself quite the best, where great angular aperture with sharp defini- tion is required. The curves have been somewhat modified from our experience in the construction of other lenses particularly those made for Dr. Max Wolf, of Heidel- berg, Germany. It departs, however, from the ordinary practice of opticians in being corrected for short wave-lengths of light. This would be quite objectless in a camera which is to be used for portraits, but is not without moment in astronomical photo- graphy. The materials employed were specially chosen for their transparency, the flint being very light and the crown very white. The focal lengths of the front and rear combinations are in a ratio of about 7 to 12, while the focal length of the system is very nearly five times the aperture. The focal length we may find very slightly modified : indeed it is our custom to balance the inevitable zonal differences of magni- fication, which difficulty is found the most formidable to all constructors of astronom- ical photographic objectives.' The camera gives a more uniformly defined field than most cameras of this type, but the definition is not sufficiently sharp to produce clear cut images. When a long exposure is made to reach faint stars there are three resulting forms of image. The fainter stars give a clear cut image, the next in brightness give an image with a dark centre surrounded by a halo, while the brighter stars give an image of uniform density but much enlarged. This variation in the images must be due to aberration, either spherical or chromatic, producing, instead of point images, discs of sensible size, possi- bly with a centre somewhat more intense than the surrounding portion. The differ- ence in the appearance of the images of stars of different brightness on the negative is thus readily explained by the light of the fainter stars not being sufficient to form a halo, as in the next brighter stars, while in the very bright stars the light is strong enough to make the halo as dense as the central portion. The only question is whether this aberration is spherical or chromatic. The most simple test for the presence of zonal errors in a lens is that of Hart- mann, the theory involved being very simple, and the equipment for the experiment FIG. 38. being within reach of any one. This method involves the determination of the point of intersection of rays of light passing through the lens at opposite ends of a diameter and equidistant from the centre. 262 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 Let L (Fig. 38) be the lens under test and consider two rays passing through a, ~b, so that Oa = Ob. These rays converge to a point A which is called the focus of these rays. If these rays are intercepted at A we find them in a single point, but if inter- cepted at E l or E 2 we find them separated by a distance d^ or d 2 - These distances may be measured with a micrometer, or photographic plates may be placed at E lf E 2 , and the distances between the resulting images measured. This latter method has been employed in the present test. Measuring the distances OA 1} OA, and d lf d 2 , we can easily obtain the correct posi- tion of focus. Let Then A = OA, OA d. = 4, = A, = A E, F. = d. d (A 1 -A l ). This is a simple geometrical property requiring no proof. Again, consider two rays passing through at of, V. If the lens is correctly ground these two rays will converge to the point A as did a and &, and so with rays from all parts of the lens. But unfortunately this is a difficult condition to obtain, the best of lenses being but a close approximation to it. In place of converging to A, a' and &' converge to some other point, say A', giving what is called zonal aberration, so that if we focus our camera for a and fe, it is out of focus for ',&', and we get a disc about our image. Take two rays at a distance Oa from the centre but on a diameter perpendicular to a, ~b, and consider their focus. If the lens is symmetrical for this zone, then the four rays will meet at the point A, their common focus, but if not symmetrical there will be two different foci for the two pairs of rays. This difference is called axial astigma- tism and can be revealed in the Hartmann test for aberration. FIG. 39 Zonal Disc. REPORT OF THE CHIEF ASTRONOMER 263 SESSIONAL PAPER No. 25a The lens is covered with a zone plate of the form shown in Fig. 39. The aper- tures are placed in ten zones of 15, 25, 35, 45, 55, 65, 75, 85, 94 and 98 mm. radius respectively. Each pair of openings is duplicated by a second pair at right angles in order to determine the axial astigmatism. In the case of the zones of 15, 25, 35, 45, 55, 65, 85 and 94 mm. radius, symmetrical pairs of apertures are placed 90 apart, but in the zones of 75 and 98 mm. radius the apertures are only 45 apart, so the outer part of the lens is more thoroughly tested than the centre. This is necessary owing to the greater amount of light admitted by the outer zones. By making an exposure at E t and another at E 2 , we can determine two positions of focus for each of the ten zones, these two positions being perpendicular to each other. An extra aperture in the zone plate enables one to identify the angle for the several zones and so avoid confusion in the determination of astigmatism. The first zone plate used had apertures of 10 mm., but the diffraction at the edges was so great that in place of solid dark spots there were circular dark rings which did not permit of accurate measurement. The second zone plate used had a diameter of 203 mm. with apertures of 5-5 mm. These plates were made of medium weight bristol board. Exposures of 6 minutes were made on Capella. In order to avoid as much as possible chromatic aberration, Seed Process plates were used, their band of sensitive- ness being narrow and confined chiefly to the blue and violet light beyond A 4600. A plate with a wider range of sensitiveness would give images so elongated radially by chromatic aberration as to render accurate measurements very difficult or impossible. All measures were made on the Zeiss comparator, the graduations reading to thousandths of a millimetre and readily estimated to ten thousandths. Test plates were first made with 4x5 Seed plates, to determine the correct time of exposure, a plate-adapter being used in the regular plate-holder. The positions corresponding to E l and E 2 were at 22 mm. and 67 mm., respectively, on the focussing scale on the camera tube. This gave the distance A^-A^ equal to 45 mm. In the appended results the focus given is that which would be used in setting according to the above men- tioned scale. The actual focus of the camera was determined as follows: The tele- scope was set midway between Castor and Pollux and a photograph taken, with the camera at its usual focus (47-5 mm. on the scale) and the zone plate removed. The distance between the images 011 the photographic plate was measured and found to be (2 = 79-5260 mm. From the Ephemeris we have E. A. Dec. Castor, 7 h 28 m 43 8 -9 + 32 5' 28'M3 Pollux, 7 h 39 m 41 8 -284 + 28 14' 56"-34 The difference in E. A. is O h 10 m 57 s - 384 = 2 44' 20" -76 Zenith distance of Castor is 57 54' 31". 87 Zenith distance of Pollux is 61 45' 3" -6 From cos a = cos b cos c + sin & sin c cos A, we have a = 4 30' 48" = the distance between Castor and Pollux. Hence, from the cotangent of a and the value of d we have the focus required f = 1060-3 millimetres. When the Correct time of exposure had been obtained, the regular 8 x 10 plates were used and a series of exposures made at E t and E.,. Although the original object in view was to test for spherical aberration at the centre, this was extended to cover the whole field of the lens and images were made extending across the plate from south to north, in order to determine the curvature of field. Nine images were obtained within the focus and nine without, their respective positions being: 264 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 Position A, 5 -3 from centre towards south end. (I T) JO (( (( II (I " C, 2- 5 " " " " a ill " " E, at centre. " F, 1 from centre towards north end. " G, 2- 5. " " " " TT AO (( (I 1C (i " I/ 5. 5 " " " " Owing to the uncertainty of the weather, exposures at positions A, B, C, D and E were made on one plate without the focus, and then exposures were made on another plate at the same positions within the focus. Exposures at F, G, H and I were then made on two other plates. This unfortunately caused a slight change in the adjust- ment of the camera and the result was an unaccountable dip in the curvature of the field. Further test plates were made at positions E, F and H, which showed clearly that the dip was not due to any fault of the lens, the resulting curve being quite uni- form, as shown in Figs. 43 and 44. The several plates were first measured for aberration and astigmatism. A sum- mary of the results is given in the appended tables and curves. As stated before, the positions E^ and E t correspond to 22 mm. and 67 mm. on the scale attached to the camera. The camera was set at 47-5 mm. to determine the focus f = 1060.3 mm. So we have 4 = 1034-8 mm. and A 2 -A 1 = 45 mm. To obtain the actual focus for each zone in the following results we must add 1034.8 mm. to each given focus. Position A shows a negative aberration of 3 -61 mm. " B " " " 3- 82 mm. " C " " " 3-75 mm. " D " " " 3-63 mm. " E " " " 3.60mm. " F " " " 3- 63 mm. " G " " " 3.64mm. H " " " 3.82mm. " I " " " 3.63mm. Such a marked aberration, extending so uniformly across the field, shows beyond any doubt the cause of the diffuse appearance of the images already referred to. The curves in Figs. 40 and 41, each division representing 1 millimetre, show very clearly the magnitude of the aberration and its uniformity across the field from south to north. Another plate R, made on the east side of the field, shows a similar aberration, curve P, Fig. 42, representing it graphically. Taking the mean focus for each zone we find the astigmatism so small as to be neglected at the centre of the field but increasing as we move outward. A closer exam- ination reveals the fact that where

=135. So we see that the apparent variation in astigmatism is due to the position of the plate and consequent distortion of some of the images rather than to any defect in the lens. As already stated, the Seed Process plate used has its maximum sensitiveness about \ 4300 in the blue light. Thinking perhaps the lens had originally been tested with yellow light, owing to the difficulty of obtaining monochromatic lighfr*in the blue, it was consequently decided to test the len by visual or yellow light. Cramer Iso- A*/ il ZS Z6 Z7 )** ZS zr &6 Z6 Z.7 Zd PLASKETT ASTROPHYSICS. IS 46 SS 66 76 &f 91 9a 2oa -p. 264 FIG- 40 Zonal Differences of Focus. PLASKETT ASTROPHYSICS. us H M to Zb zr n Z3 & Z5 FIG. 41 Zonal Differences of Focus. M ** 23 36 Iff SS OJ TJ* (fff 94 30 ,00 /V FIG. 42 Zonal Differences of Focus. PLASKETT ASTROPHYSICS. zz 3 -e/ 23 2.1 22 Z.4 4S T Z2 zs 24 ZS 56 T ^2 66 "T ZZ, & FIG. 43 Curvature of Field at different Zones. 7S: ZS Z6 s PLASKETT A STROPH YSICS. ' 3' f S' 25a p. 264 FIG. 44 Curvature of Field at different Zones. REPORT OF THE CHIEF ASTRONOMER 265 SESSIONAL PAPER No. 25a chromatic plates were substituted for the Seed Process plates and a yellow screen was placed just above the plate-holder to cut out the blue and violet light. The Cramer plate was used as it has a band of sensitiveness in the yellow-green light about X 5650, as well as the band of sensitiveness to blue and violet light possessed by all plates. Three exposures were made within the focus and three without, their positions being: Position L, 50' from centre to south. M, at centre. N, 5tf from centre to north. The exposure in each case was 5 minutes. Comparing these with positions A to I, we find the aberration less by about 0-6 mm. Position L showing negative aberration of 2.77mm. " M " " " 3.03mm. " N " " " 2- 78 mm. But it is not small enough to indicate any special adjustment of the lens surface to yellow light. The uniformity of the aberration is shown in L, M, N, Fig. 42. The astigmatism is similar to that shown by the Seed Process plate. A uniform increase of about 3-5 mm. in the focus, as compared with the blue light, is due partly to refraction of the light in passing through the yellow screen. The screen being about 6 mm. thick, the refraction would lengthen the focus by about 2 mm., the refractive index of glass being about 1-57. The remaining 1-5 mm. is due to the difference in focus of blue and yellow light. Combining the results of positions A to I (see table XIV.), we have the focus of each zone of the lens at nine different points extending from 5 -3 on one side of the centre to 5 -5 on the other side. Figs. 43 and 44 show the curvature as given from these foci, the coordinates being the diameter of the field in degrees and the zonal foci in millimetres. As in the case of the aberration these curves are very uniform, indi- cating a difference of about 2. 5 mm. between the focus at the edge of the field and that at the centre. Since the zonal foci of the lens vary so much from the centre to the edge no one position of focus is suitable to all the lenses. To obtain a uniform field and at the same time get as sharp a definition as possible, we must study the effect produced by the various zones when out of focus. If we set, for example, the camera at the focus of the zone with radius of 65 mm., then other zones will be out of focus and there will be discs or circles of confusion about each image. The density and size of these circles depend on the extent to" which the several zones are out of focus and also on the area of these zones. The diameter of these circles of confusion may be determined as follows : (F-F ~) *-*r< where d = diameter of circle of confusion, r - radius of zone, F = focus of zone, F = locus at which the camera is set. This determines for us the circles of confusion but it does not give us any idea of the effect on the image. A circle of confusion of 20" diameter and produced by a zone of 15 mm. radius would not be nearly so injurious to the image as one of the same diameter produced by a zone of 75 mm. radius. We see that simply determining the circles of confusion for the several zones will not give us the effect of the circles on the images, and so will not aid us in adjusting the camera to obtain the best imag?s 266 9-10 EDWARD VII., A. 1910 possible under existing conditions. We must determine at what position of focus the lens is most efficient. The following formula by Hartmann gives a test for the effi- ciency of a lens at various foci : 200000 Sr 2 (ff-ffp) ~F\T ~^~ where T = efficiency of lens, F = focus of zone, F = focus at which the camera is set, r = radius of zone. (100000 is introduced simply to transfer the decimal point and so avoid exceed- ingly small numbers.) According to this test an objective is moderately good when T is greater than 1-5, good when T is between 0-5 and 1-5, and exceedingly good when T is less than 0-5. But as this criterion of efficiency refers to telescope objectives where the field of view and angular aperture are small, it is not an accurate test for photo- graphic objectives of wide aperture. Using the above formula, the best positions of focus at the several positions, A, B, C, etc., were obtained. Table XV. gives these foci, the diameters of the circles of confusion, and the efficiency of the lens. Curve 8 f Fig. 44, shows the combined results for the several positions A to I. From this curve it may be concluded that the best uniform field would be obtained by setting the camera at 25-75 mm. or 26-0 mm. Testing for Chromatic Aberration. f Although the foregoing tests revealed a much greater spherical aberration than is consistent with the production of good negatives, objection was taken to the statement that this aberration was the cause of the observed defects in the images. Accordingly it was decided to test for chromatic aberration also. The camera was detached from the telescope and mounted on a table, the source of light being an arc-lamp about 400 yards distant. The spectrograph was placed with the slit at the focus of the camera which was in line with the collimation tube. A cardboard disc was placed over the camera objective, the light entering through two ' oblong openings, 3 mm. by 8-5 mm., symmetrically placed on a common diameter. Exposures were made with the slit first inside the camera focus and then outside, isochromatic plates being used to obtain the D lines. Images of the slits in the disc were thus obtained as produced by light of various wave-lengths. By measuring the distances between these images at twelve points and applying the Hartmann formula ; the focus of the camera was obtained for twelve different wave-lengths, as shown in the following table: Wave-length. Focus. A 5893, D 41-93 mm. 5500 41-24 " 5180 40-33 " 4880F0 39-30 " 4737 39-07 " 4520 38-62 " 4370 38-73 " 4230 38-79 " 4115 39-00 " 4020 39-71 " 3933, K 39-98 " 3780. . 40-88 " REPORT OF THE CHIEF ASTRONOMER 267 SESSIONAL PAPER No. 25a Fig. 45 represents graphically the various foci and the chromatic aberration. The minimum focus is about Hy and, while there is a range of 3-12 mm. in focus in the region between A 5893 and A 3780, there is less than 1 mm. range in the photographic region. J) m K FIG. 45 Chromatic Aberration Curve . Comparing this with the test for spherical aberration we have (a) Minimum spherical aberration of - 3 -6 mm. (b) Maximum chromatic aberration in photographic region of 1 mm. Even if we allow for the chromatic aberration of 3 mm. at \ 5893, the light here is not rich enough in actinic properties to produce the observed halo. It seemed, therefore, unnecessary to continue the investigation re chromatic aberration. Changing the Distance between the Components of the Outer Combination. Prof. Hastings, of Yale University, who had been kept informed of the results of these tests, suggested that there might be sufficient internal reflection between the components of the objective to produce the observed halo and that this might be elim- inated by increasing or decreasing the separation. Although we still felt that the defect was due to spherical aberration, this suggestion coming from the designer of the lens claimed our most careful attention and a series of tests were accordingly made. The original separation (one thickness of a postage stamp) was removed and new separations of various thicknesses used. Little blocks built up from bristol board were used until the best adjustment was obtained, after which hard rubber blocks were used. The following table shows the tests and results: Date. Separation of Components. Focus.* Spherical Aberration. Description of Images. 1908. Jan 004 inches. 47 ' 5 mm. - 3'6 mm. Described in first part of appendix. 1909. Jan. 12. . . 0'012 M 4^-0 M No change. i 26. ... Tissue paper. 47-5 ,i Feb. 2. ... 47'5 H i" and " discs were placed on lens to cut off outer portion, but there was very little improvement. .. 25 Apr. 20 0-132 inches. 0-070 M 26'5 ,, 36-5 + 2'4 mm. - 0-5 .. Images about the same as originally. Images much improved. Halo greatly reduced. May 25 0-077 i, 36-0 ,, - 0-3 ,. Images much the same as with .070 separation. ' Focus here refers to the scale on the camera tube. 268 DEPARTMENT OF TEE INTERIOR 9-10 EDWARD VII., A. 1910 Curve a, Fig. 46, shows the aberration with a separation of 0-004 inches, curve ft shows the aberration with a separation of 0.132 inches, and curve y shows the aberra- tion with a separation of 0-070 inches. Figure 47 shows cuts of the Pleiades takvn with the different separations. Examining the above table it is seen that increasing, the separation, shortened the focus and changed the aberration. Coincident with the change in aberration there was a decided change in the star images. Aberrations of - 3-6 mm. and + 2-4 mm. were accompanied by a very marked halo, while with an aberration of - 0-5 mm. the halo was negligible. Changing the separation to 0-070 inches has undoubtedly improved the objective as the field remained practically unchanged, and the halo was so small as to be neglected. But that this improvement has been effected by the removal of internal reflection does not seem at all probable. On the contrary, the above results seem to me to be but additional proof that the observed halo has been caused by spheri- cal aberration, as was stated at the beginning of this appendix. It is not at all likely that the aberration and the halo would disappear simultaneously if the halo were caused by internal reflection. Note. Since the conclusion of the above work a communication has been received from the makers of the objective, stating that they also believe the defect to be due to spherical aberration and expressing their willingness to remove it without additional charge. TABLE I. ZONAL Foci : POSITION A. Radius of Zone rfi d, Focus. Mean. Astigmatism. 15 mm 45 mm. 0-6450 mm. 6826 21'86 +0-20 25 135 0-6333 1-0432 0-6938 1-1627 21-47 21-28 21 66 -0-19 -0'37 35 90 45 1-0746 1-5131 1-1201 1-5651 22 03 22 12 21-65 + 0-38 + 0'23 45 135 1-4948 1-9259 1-6115 2-0621 21-66 21-73 21-89 -0 23 0"44 55 90 45 1-9921 2-4355 1-9715 2-3590 22-62 22-86 22-17 +0-45 +0'26 65 135 o 2-4166 2-8795 2-4523 2-8646 22 34 22'56 22'tiO -0-26 0"05 75 90 22'5 2-9851 3 4195 2-7288 3-1358 22-66 23 47 22 61 + 0'05 -0'15 67'5 3-5344 3-0497 24'lfi + 0'54 112 5 3-4794 3 -lOWi 23 77 '' +0'15 85 ;.. 157-5 45 3-3935 4-0807 3-2266 3-3663 23-07 24'66 23-62 -0-55 + 0'29 94 135 o 4-0195 4-5566 3-4899 3-7376 24-09 24 72 24 37 -0-28 90 24 '72 98 22'5 4 '8567 3 '7280 25 '46 + 0'20 67'5 112-5 157-5 4-8157 3 8320 25-0(5 25-26 -0-20 ' *o 10 CV d, d, Focus. Mean. Astigmatism. 15 mm 45 mm. 0-7003 mm. 0-6365 23 '57 -0'04 25 135 7023 i'1571 0-6334 1-0546 23-66 23 54 23-61 + 0-05 -O'lO 35 90 45 1-1701 1-6446 1-0470 1 4542 23-75 23'88 23 64 +0-11 + 0'05 45 135 1-6394 2-1303 1-4625 1-8615 23-78 24 02 23 83 -0 05 -0 10 55 90 45 2-1444 2-6238 t'8404 2-2009 24-22 24-47 24 12 +0-10 + 0'05 85.... 135 o 2 6415 3'1652 2-2368 2'5791 24-37 24-80 24-42 -0-05 -O'Oo 75 90 22'5 3-1857 3-7187 2-5686 2'8718 24-91 25-39 24-85 + 0-06 -O'Ol 67'5 3-7533 2'8700 25 50 + 10 112'5 3-7401 2-8848 25'40 O'OO 85 .. 157 5 45 3 7206 4-8530 2-8957 3 1223 25 30 26'20 25 40 -o-io -I-0-07 94 135 4 3522 4 -95(50 3 1638 3 3371 26-06 26-89 26 13 -0-07 -0'09 08 " 90 22'5 5-0073 5'2 15 3 3159 3 3850 27 07 27 32 26-98 + 0-09 -0'04 67 5 5 2741 3-3635 27'48 + 0'12 112-5 5 '2528 3-3800 27 '38 +0'02 157-5 5 2405 3-4089 27-26 27 36 -o-io 270 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 TABLE IV. ZONAL Foci : POSITION D. Radius of Zone. d, d 2 Focus. Mean. Astigmatism. 45 mm. 0-7204 mm. 0-6208 24-17 -0-03 25 . . 135 0-7128 1-1883 0-6106 1-0255 24-24 24-15 24-20 + 0-04 -0-02 35 90' 45 1-1963 1-6786 1 0292 1-4273 24-19 24-32 24-17 + 0-02 -t 0-04 45 135 1-6764 2-1796 1-4340 1-8131 24 25 24-57 24-28 -0-03 -0-02 55 90 45 2-1843 2-6726 1-8102 2-1618 24-61 24-88 24-59 + 0-02 -o-oi 65 135 2-7039 3-2398 2-1805 2-5165 24-91 25-33 24-89 + 0-02 -0-02 75 90 22'5 3-2503 3-7991 2-5140 2-8022 25-37 25-90 25-35 + 0-02 + 0-03 67'5 3-8159 2-8151 25'90 4-0-03 112-5 3 8110 2-8295 25'83 -0'04 85 157-5 45 3-8084 4-4340 2-8193 3-0715 25-86 26-58 26-87 -0 01 +0-01 94 135 4-4454 5-0594 3-0862 3-2538 26-56 27-39 26-57 -o-oi -0'03 98 90 22'5 5-0882 5-3326 3-2528 3-2971 27-45 27'81 27-42 + 0-03 + 0'01 67'5 5'34i<5 3-3117 27 '78 -0'02 112'5 5-3394 3-3005 27'81 -fO'Ol 157-5 5-3453 3-3101 27-79 27-80 -o-oi TABLE V. ZONAL Foci: POSITION E. Radius of Zone. di d 2 Focus. Mean. Astigmatism 15mm 45 mm. Q'7243 mm. 0'6159 24-32 + 0'03 25 135 0-7189 1-1937 0-6145 1 -0189 24-26 24-28 24 29 -0-03 -0-02 35 90 45 1-2020 1-6S84 1-0215 1-4238 24-33 24-41 24-30 + 0-03 + 0'0l 45 135 1-6907 2-1965 1-4277 1-8049 24-40 24'70 24-40 o-oo o-oo 55 90 45 2-1948 2-6918 1-8038 2-1478 24-70 25'03 24-70 o-oo + 0'02 65 135 2-7202 3-2594 2-1765 2-5023 25-00 25 '46 25-01 -o-oi o-oo 75 90 22'5 3 2631 3-8166 2-5050 2 '7969 25 46 25-97 25-46 o-oo -O'Ol 67'5 3 '8365 2'8062 25'99 + 0'01 112'5 3-8381 2-8112 25-97 -0 01 85 157-5 15 3-8347 4-4596 2-8057 3-0610 25 99 26 ' 68 25-98 +0-01 O'OO 94 135 4-4751 5-0876 3 0733 3 2357 2f>-68 27'51 26-68 o-oo o-oo 98 90 22'5 5-1113 5'3623 3-2509 S'2966 27-51 27 '87 27-51 00 -0'02 67'5 5-3789 3 29! H 27'89 O'OO 112 5 5 3738 3-3000 27'88 -o-oi 157-5 5-3729 3-2913 27-91 27'89 + 0-02 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a TABLE VI. ZONAL Foci : POSITION F. 271 Radius of Zone. di d, Focus. Mean. Astigmatism. 15 mm. ... 45 mm. G'7396 mm. 0'6078 24'70 + 0'11 25 135 0-7315 1-2242 0-6130 1-0149 24-48 24-60 24 59 -o-ii -0'04 35 90 45 1-2304 1-7274 1-0127 1-4155 24-68 24-73 24-64 + 0-04 +0-01 45 135 1-7267 2 2431 1 4160 1'7927 24-72 25 01 24-72 o-oo -0'03 55 90 45 2 '2483 2-7507 1-7875 2-1330 25-07 25-35 25-04 + 0-03 + 0'01 65 135 2-7761 3-3281 2-1567 2-4797 25-33 25-79 25'34 -o-oi -O'Ol 75 90 22'5 3 3424 3-9033 2-4826 2 '7731 25-82 26 '31 25-80 + 0-02 -0'02 67'5 3-9215 2-7751 26-35 -t-0'02 112'5 3-9230 2-7794 26-34 + 0'01 85 157-5 45 3-9134 4-5513 2-7826 3-0286 26-30 27'02 26-33 -0-03 O'OO 91 135 4-5709 5 1894 3-0376 3 '2095 27-03 27'80 27-02 +0-01 -0'04 98 90 22'5 5-2240 5-4615 3-2063 3-2621 27-88 28'17 27-84 + 0-04 -0'05 67'5 5-4831 3-2539 28-24 + 02 112-5 5-4846 3-2448 28-27 + 0-05 157'5 5-4797 3-2630 28-21 23-22 -o-oi TABLE VII. ZONAL Foci : POSITION G. Radius of Zone. *, d 2 Focus. Mean. Astigmatism. 15 mm 45 mm. 0-7307 mm. G'6203 24-29 -hO'04 25... 135 0-7256 1-1958 0-6228 1-0336 24-22 24-14 24-25 -0-03 -O'lO 35 90 45 1-2129 1 ' 7039 1 0297 1-4425 24 34 24 '37 24 24 +0-10 + 0'01 4 135 1-6995 2-2025 1-4409 1-8339 24-35 24-55 24-36 -o-oi -O'lO 55 90 45 2-2164 2 '7161 1-8137 2'1758 24-75 25'00 24-65 +0-10 + 0'03 65 .. 135 o 2-7339 3'2652 2-1962 2'5402 24-95 25'31 24-97 -0-C2 -0'12 75 90 22'5 3-2975 3-8418 2-5100 2 '8348 25-55 25-89 25-43 + 0-12 -0'07 67'5 3-8710 2-8123 26-06 + 0'10 112-5 3-8743 2-8281 26'01 + 0'05 85 157-5 45 3-8565 4 ' 5039 2-8481 3'0808 25-88 26 '72 25-96 -0-08 + 0'04 94 135 o 4-5072 5-1090 3-1024 S'2893 26-65 27 '38 26-68 -0-03 -0'13 98 90 22'5 5'1685 5-3913 3-2472 3-3340 27-64 27 '80 27-51 + 0-13 -0'08 67'5 5-4340 3-3009 28'00 + 0']2 112-5 5-4298 3-3093 27 '96 + 0'08 157-5 5-3990 3-3450 27-78 27-88 -o-io 25a 20 272 9-10 EDWARD VII., A. 1910 TABLE VIII. ZONAL Foci : POSITION H. Radius of Zone. * <*t C? 2 Focus. Mean. Astigmatism. 15 mm . 45 mm. 0-7033 mm. 0-6505 23-38 +0'04 25 135 0-7010 1-1515 0-6528 1-0961 23-30 23-05 23 34 -0-04 -0 31 35 . 90 45 1-1775 1-6507 1-0610 1-4920 23-67 23-64 23-36 + 31 + 0-07 45 135 1-6408 2-1198 1-5005 1-9152 23-50 23-64 23 57 -0-07 -0-27 55 90 45 2-1580 2 6321 1-8560 2-2501 24 19 24-26 23-91 + 0-28 + 0-06 65 135 2-6458 3-1527 2 '2870 2-6581 24-14 24-41 24-20 -0-06 -0-26 75 90 22'5 3-2126 3-7121 2 5830 2-9610 24-94 25'03 24-67 +0-27 -0 16 67'5 3-7705 2-9036 25-42 +0-23 112-5 3-7646 2-9178 25-35 +0-16 85 157-5 45 3-7126 4-3805 2-9823 3-1994 24-95 26-01 25-19 -0-24 +0-06 94 135 4-3703 4-9372 3 2255 3-4590 25-89 26-46 25-95 -0-06 -0 33 98 90 22'5 5-0597 5-2258 3-3340 3-4928 27-13 26-97 26-79 +0-34 -0-19 67'5 5-3153 S'4031 27-43 + 0-27 112'5 5 3021 3'4164 27-37 + 0-21 157-5 5-2219 3-5158 26 89 27-16 -0-27 TABLE IX. ZONAL Foci : POSITION I. Radius of Zone. rf, d% Focus. Mean. Astigmatism. 15 mm 45 mm. 0-6675 mm. 0-6798 22'29 + 0'14 25 135 0-6580 1-0786 0-6869 1-1508 22 02 21 'T 7 22 15 -0 13 -0-53 35 90 45 1-1344 1-5761 1-1005 1-5551 22-84 22'65 22-30 +0-51 + 0'17 45 135 1-6518 1-9937 1-5765 2-0341 22-32 22-27 22-48 -0-16 -0-55 55 90 45 2-0805 2-5249 1-9245 2-3421 23-38 23-34 22-82 +0-56 +0-16 65 135 2 5131 2 '9778 2-3998 2-8323 23-02 23-06 23-18 -0-16 -0-59 75 90 22'5 3-1123 3-5401 2-6623 3-1225 24-25 23'91 23-65 +0 60 -0-30 67'5 3-6580 2-9877 24 77 + 0-56 112-5 S'6314 3-0360 24-51 +0 30 85 157-5 45 3-5107 4 '2245 3-1646 3-3275 23-67 25'17 24-21 -0-54 +0-20 94 135 4-1720 4-7029 3-4060 3 '6958 24-77 25 '20 24-97 -0-20 90 25 20 98 22'5 5 "0145 3'6885 25-93 + 0'15 67'5 112-5 157-5 4-9712 3-7578 25-63 25-78 -0-15 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a TABLE X. ZONAL Foci: POSITION L. 273 Radius of Zone. a, d% Focus. Mean. Astigmatism. 15 mm 45 mm. 0'8580 mm. 0-5011 28 41 + 0-03 25 135 0-8478 1-4122 0-4980 8305 28-35 28-34 28-38 -0-03 -0-02 35 90 45 1-4257 2-0004 0-8345 1-1616 28-38 28-47 28-36 + 0-02 -0-04 45 135 2-0018 2-5920 1-1533 1-4647 28-55 28'75 28-51 + 0-04 +0'03 55 90 45 2-5883 3-1567 1-4712 1'7504 28-69 28-95 28-72 -0-03 -0-05 65 135 3-1968 3-8030 1-7537 2-0479 29-06 29-25 29 00 + 0-06 -o-oi 75 90 22'5 3-8094 4'4142 2-0455 2-2996 29-28 29'59 29-26 +0-02 -0-08 67'5 4 '4469 2-2925 29-69 -+0 02 112 '5 4-4305 2-2881 25-68 H-O-OI 85 ... . . 157-5 45 4-4525 5'1293 2-2920 2-5171 29-71 30-19 29-67 +0-04 -0-05 94 135 5-1351 5-7911 2 4940 2-6695 30-29 30'81 30 24 +0-05 -0-04 98 90 22'5 5-8120 6-0783 2-6555 2-7200 30-89 31-09 30-85 + 0-04 -0-06 67'5 6'0767 2 '6950 31-17 +0'02 112 '5 6'0729 2 '6946 31-17 +0'02 157-5 6-0908 2-7050 31-16 31-15 +0-01 TABLE XI. ZONAL Foci : POSITION M. Radius of Zone. tf, d, Focus. Mean. Astigmatism. 15mm 45 mm. 0'8617 mm. 0*5145 28'18 + 0'02 25 135 0-8519 1-4154 0-5111 Q'8238 28-13 28'44 28-16 -0-03 -0'02 35 90 45 1-4309 2-0053 0-8295 1-1647 28-49 28-47 28-46 + 0-03 -0-06 45 135 2-0039 2-5951 1-1490 1-4685 28-60 28 '74 28-53 + 0-07 -0 01 55 90 45 2-5865 3-1740 1-4601 1-7598 28-76 28'95 28-75 +0-01 -0-08 65 135 3-2043 3 '8230 1-7498 2-0360 29-11 29-36 29-03 +0-08 O'OO 75 90 22'5 3-8263 4 '4467 2-0381 2-2842 29-36 29-73 29-36 o-oo +0-03 67 '5 4-4591 2'2817 29-59 -0 11 112 '5 4-4541 2 ' 2803 29'76 + 0-06 85 157-5 45 4-4353 5-1375 2-2760 2-4931 29-74 30'30 29-70 + 0-04 +0-05 94 . 135 o 5-1476 5 '8073 2-5197 2 '6596 30-21 30'86 30-25 -0 04 "-O'Ol 98 90 22'5 6-8189 6'0981 2-6630 2 '6932 30-87 31 '21 30-87 o-oo + 0-02 67 '5 6'1118 2'7059 31'19 o-oo 112'5 6-0862 2 '7090 31-14 -0'05 157-5 6-0983 2-6950 31-21 31-19 + 02 25a 204 274 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 TABLE XII. ZONAL Fo 31 : POSITION N. Radius of Zone. di d 2 Focus. Mean. Astigmatism. 45 mm. 0'8573 mm. 0-4968 28-49 + 0-07 25 135 0-8578 1-4272 0-5042 0-8332 28-34 28-41 28-42 -0-08 -0-05 35 90 45 1-4232 2-0043 0-8235 1-1518 28-51 28-58 28-46 + 0-05 -0-02 45 135 o 2-0138 2'6017 1 1536 1-4565 28-61 28'85 28-60 +0-01 + 0'04 55 90 45 2-5934 3-1837 1-4642 1'7478 28-76 29-05 28-81 -0-05 00 65 135 3-2112 3-8245 1-7647 2-0250 29-04 29-42 29-05 -0 01 +0-01 75 90 22'5 3-8307 4-4507 2-0334 2-2902 29-40 29-71 29-41 - O'Ol -0-04 67'5 4 '4655 2'2819 29 '78 + 0-03 85 112-5 157-5 45 4-4729 4'4521 5'1540 2-2797 2-2895 2-5082 29-81 29-72 30-27 29 : 75" + 06 -0-03 0-02 94 . 135 5-1560 5 '8248 2-4981 2-6439 30-31 30-95 30-29 + 0-02 + 03 98 90 22'5 5-8086 6'0993 2-6549 2 '6965 30-88 31-20 30-92 -0-04 O'OO 67'5 6 '1101 2'7062 31-19 - O'Ol 112 '5 6 '1006 2 '6947 31'21 + 01 157-5 6-0933 2-6951 31-20 31-20 o-oo TABLE XI [I. ZONAL Foci: POSITION R. Radius of Zone. di ' d 2 Focus. Mean. Astigmatism. 15mm 45 mm. 0'6950 mm. 0-6533 23 20 + 0-18 25 135 0-6707 1 ' 1187 0-6506 riooo 22-84 22'69 23-02 -0-18 -0'23 35 90 45 1-1413 1-6051 1-0780 1-5079 23-14 23'20 22-92 + 0-23 + 0'08 45 135 o 1-5904 2-0648 1-5168 1-9508 23-03 23'14 23-12 -0-09 -0'30 55 90 45 2-0968 2-5811 1-8769 2-2793 23 74 23'90 23-44 + 0-30 + 0-12 65 135 2-5683 3-0716 2-3143 2'7009 23-67 23-94 23-78 -o-ii -0-28 75 90 22 5 3-1285 3-6463 2-6173 2-9964 24-50 24'70 24-22 + 0-28 -0'09 67'5 3-6927 2 '9238 25'11 + 0'32 112'5 3-6642 2-9616 24 89 +0-10 85 . 157.5 45 3-6180 4 '2992 3-0345 3'2352 24-47 25'68 24-79 -0-32 + 0-15 94 135 4-2542 4'8501 3-2864 3 "5156 25-39 26 '09 25-53 -0-14 -0'30 98 90 22 5 4-9240 5-1406 3-3800 3-5317 26-68 26 '67 26-39 + : 29 -0'12 67-5 5-2145 3-4394 27'12 + 0-33 112-5 5-1649 3 '4780 26'89 +0-10 157 5 5-1125 3 5791 26-47 26-79 -0-32 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a TABLE XIV. ZONAL Foci. 275 Radius of Zone. Position. A B C D E F 15 mm . ... 21-66 21-65 21.89 22-17 22-60 22-61 23 62 24-47 24-72 25-26 22-69 22-76 22-92 23 22 23 56 23-99 24-57 25-31 26-18 26-51 23-61 23-64 23-83 24-12 24-42 24-85 25-40 26-13 26-98 27-36 24-20 24-17 24-28 24-59 24-89 25-35 25-87 26-57 27-42 27'80 24-29 24-30 24-40 24-70 25-01 25-46 25-98 26-68 27-51 27-89 24-59 24-64 24-72 25 04 25-34 25-80 26-33 27-02 27-84 28-22 25 .. 35 45 55 65 75 85 94 98 G H I L M N 15 mm 24-25 24-24 24-36 24-65 24 97 25-43 25 96 26-68 27-51 27'88 23-34 23-36 23 57 23 91 24-20 24-67 25-19 25-95 26-79 27 16 22-15 22-30 22-48 22-82 23-18 23 65 24-21 24-97 25-20 25-78 28-38 28-36 28-51 28-72 29-00 29-26 29-67 30-24 30-85 31-15 28-16 28-46 28-53 28-75 29-03 29-36 29-70 30-25 30-87 31 19 28-42 28-46 28-60 28-81 29-05 29-41 29-75 30-29 30-92 31-20 25 35 45 55 65 75 85 94 98.. TABLE XV. Plate. Best Focus. Confusion Circle. Efficiency. A.. 24 5 44'2 11-46 B... 25'5 38 '5 13-43 C.... 26 25 39-2 13-11 D. 2H'75 37'9 13 01 E 26'8 38-5 12-77 F.... 27-00 43-1 12-56 G.... 26 7 417 12'71 H.. 26 00 41'00 13-08 I 25-00 36-00 10-52 L 30'20 33-3 9-64 M 30 '25 33-0 9-47 N 30 30 31-7 9 38 276 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 TABLE XVI. ZONAL TEST. Settings 6'5 & 51 '5 ; Separation 0'132 inches. Radius of Zone. d, *, locus. Mean. 15 11.111 . ...... 45 mm. 0-6422 mm. 0-7178 21-25 25 135 0-6389 1-0595 0-7130 1-1848 21-27 21-24 21-26 35 90 45 1-0605 1-4779 1-1895 1-6885 21-21 21-00 21 22 45 135 1-4683 1-8743 1-6827 2-1880 20-97 20-76 20-98 55 90 45 1-8729 2-2487 2-1754 2-6728 20-82 20-56 20 79 65 135 2-2606 2-6086 2-6841 3-2090 20-57 20-18 20- 6 75 90 22'5 2-6180 2-9475 3-297 3-7395 19 91 19-83 20-04 85 67-5 112-5 157-5 45 2-9587 2-9633 2-9505 3-2795 3-7468 3-7468 3-7495 1 3160 19 86 19-87 19-82 19-43 19-84 94 135 3 2858 3-5285 4-3213 4-8575 19 44 18-93 19-43 98 90 22'5 3-5398 3-6505 4-8555 5 0963 18-97 18'78 18-95 67-5 112-5 157'5 3-6643 3-6723 3-6566 5-0935 5-0755 . 5 0691 18-83 18-89 18-86 18-84 TABLE XVII. ZONAL TEST. Settings 16 '5 & 61 '5 ; Separation 0'070 inches. Radius of Zone. d, f Focus. Mean. 15 mm .....' o 45 mm. 0-6014 mm. 0'7332 20'23 25 135 0-5953 Q'9944 0-7372 1-2348 20-10 20'07 20-16 35 ; 90 45 0-9931 1-3921 1-2375 1-7460 20-03 19'96 20'05 45 135 1-3905 1'7970 1-7501 2'2300 19 93 20'08 19-95 55 90 45 1-7882 2'1784 2-2236 2'7251 20-06 19-99 20'07 65 135 2-1720 2'5940 2-7159 3 "2068 19 99 20'12 19-99 75 90 22'5 2-5899 2 '9884 3 2110 3 '6893 20-09 20'14 20 11 85 67'5 112-5 157-5 45 2-9855 2-9914 2-9805 3'4127 3-6896 3-6926 3-6919 4 1765 20-13 20-14 20-10 2Q-24 20-13 94 135 G 3 4084 3-7945 4-1754 4 ' 5940 20-22 20 '36 20-23 98 90 22'5 3-7910 3 ' 9770 4-6020 4"7611 20-33 20 '48 20-35 67-5 112-5 157-5 3-9740 3-9755 3-9755 4-7611 4-7650 4 7735 20-47 20-47 20-45 20-47 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a TABLE XVIII. SETTINGS 16 5 AND 61 '5; 0'077 SEPAKATION 277 Radius of Zone. * *, d 2 Focus. Mean. 15 45 mm. 0-5717 mm. 0-7561 19-38 135 0-5830 0-7540 19-38 25 0-9550 1-2645 19-36 35 * ... 90 45 0-9549 1-3335 1-2662 1-7745 19-35 19-31 19-36 45 135 1-3365 1-7208 1-7831 2-2832 19-28 19 34 19 30 55 90 45 1-7228 2-0918 2-2750 2-7819 19-39 19-31 19-37 65 135 2-0909 2-4909 2-7681 3-2762 19-36 19-44 19 34 75 90 22-5 2 4915 2-8593 3-2844 3-7774 19-41 19-39 19-43 85 67'5 112-5 157-5 45 2-8637 2-8707 2-8585 3-2567 3 7804 3-7829 3-7694 4-2874 19-39 19-42 19-41 19-43 19-40 94 135 3 2742 3-6387 4-2702 4-7187 19-53 19-59 19-48 98 90 22-5 3-645H 3-7929 4-7240 4-9030 19-60 19-63 19-60 67'5 112-5 3-7942 3-8191 4-9054 4-8918 19-63 157-5 3-7988 4-8958 19 66 19-64 278 DEPARTMENT OF THE INTERIOR H g SI 30. O 9-10 EDWARD VII., A. 1910 N -C -Sum :O r -Sum a * I N IN N d O-3i-t-*--COt t- t- O t- o i> to rH ; rH rH IN rH rH *OC^IN(NOOOCO>OO : : : : - ' ' ' ' '<=>& woiNoo^rH : : : : 00 to to i i i i i i i i i i :::::.:::: i i i i i : : : : rH rH *> O CO IN OlOOOOO O <* -O -OO 1C 00 (N 00 TH to O 00 ooocoto eo ^t"ro so?ot^rH IN cC'-f io.eo cc(NeccoeOrH =INO i i i i i i i i i i : i : i i i i i i i (NrH t-(~- rHrH OO *<$ Or-( r r r :IM ; - r : r 280 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910, Remarks. i 3* .ta O f- 1 . Pq PH PH P-i PH PH PH P-i P-i P-i P-i PH PH P-i PH PH P-i PH & PH H PH PH PH 0- # . &io fQ ' v 02 | = = ; ; ; ; ; i| = :r |=|=| = = ;| = : | 43 CO 1O CD CD O CD 8-8 8 ' 8 - 'S 8 1 l-l " "" rH i i i i i : i j I w B P3 W 2 t> o C -Saiu < to o) oo i - oo o^ to o o IQ oc * i~t i i lr"*t-"TtO O _ _ 30 i | Sum iH ii i 1 iH i < iH 1 1 1 1 1 1 J 1 I 1 II i QX Cb 02 "So . V w* fe - = = = = SH - = =fe = r =a = = = = =>' = = = - = H - = = = ^ 00 ' e ' TH 000 i ^ i-HIN O Oi-lrH iH rH O O rH i-l iH rH O O O O O O O l-l iH r-l IM i-i l-l O O O O uoi^ina g O OOOb-IMOO **''O} O ..-c^O > '*'O > OO'' ; ; i I 1 i : T 1 ... ,_! . . . ,_| . . . ,1 . T-H i i i : : : i i : : : i i : : : : i : i : : : . 1 Oi-ieO CO ; CN -. OJ OO O Is..... ' 00 00 1 1 . i i i : i i : ' i i : : : i : : : : i : i : : : IQ o w * : O sO sO IO O O -sOO -O -O ec 5% '- 5O OO rH i 1 T-I iH : O : = lO T- I N -CO . . . . I 1 1 1 I 1 -H T-I T-I T 1 N < N II . . . . ' z boo sb CO tcco 1 1 : i 1 1 i i i : : : : : i i : : i : : : : : i i : : ; OOOtHOOOOO CO8oi^o8o*M8o'S^M5s5lo8oT-i'5<^8 ; *5.t^t-t^t^^oococ OV -O N N -OO 5 s ! N i -in -CO iH -if) -iH -C<1 ( : : t : : i : : i i : : i : : : . : i : : : . : i : : O COCO 5 -M -O OW O * lOi-l :::+::+:'+::: i i : : : : i : : i i i ::::::: i ::::: i ::: ss o -001010 -o -o 10 to- f'-coecKN .er> ...- ! 284 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910' O S v Sum eo--ooo s - a M j 1 rj l^ 8 IM rH (N c<5 TMO << i REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 285 286 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 1008. Jan. 20. G. M. T. 15 h 00 m j8' ORIONIS 1241 . Wt. Mean of Settings. Corrected Star Settings. Disp' in rev na Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. 2 54-0256 U 53'1058 3 2 53-0008 53-4440 0048 4490 0350 0467 + 40-28 53-40 3" 2 45-2624 45-2628 2724 0337 + :>5-17 Weighted mean -f 41 ' 64 V a -17-93 Va- - -09 Curvature - 28 l'J08. Jan. 20. G. M. T. 15 h 00" Radial velocity + 23'3 /3 ORIONIS 1241 b. Wt. Mean of Settings. Corrected Star Settings. Disp 1 in rev" 9 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. 2 54-7354 2 53-1094 2 54'0270 3 45-2712 '2755 '0368 + 38'41 3 54-0008 0048 0350 + 40-28 2 45-2684 1 53-4328 4360 0337 +38-54 Weighted mean . V a Vd Curvature. -17-93 09 - '28 + 39-23 Radial velocity + 20'9 1908. Jan. 20. G. M. T. 15 h 00 j8 ORION IS 1241 c. Measured by \ T q p rA <, KirTT Observed by J J ' b ' L LASKET1 - Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 3 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp 1 in rev" 8 Velocity. 54-7640 53-1358 54-0552 45 '2960 2 1 54-0360 53-4715 0130 4485 0448 0462 + 51-56 + 52-83 3 45-2952 2727 0340 + 35-49 Weighted mean +43'74 V a -17-93 Vd '09 Curvature . - '28 Radial velocity + 25'4 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a ^ORION IS 1247 . 287 1908. Jan. 20. Observed by \ T e T> G. M. T. 15" If, Measured by ) J " S " P^SKETT. Wt. Mean of Settings. Correc ted Star Settings. Disp' in rev 1 " Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in re\ ns Velocity. > "2 3 3 54-7385 54-0270 54-0012 53-4384 2 2 2 53 1054 45-2652 45-2653 2737 0350 +36-53 0052 4434 0354 0411 + 40-74 + 47-00 Weighted mean . 4-42 03 -17 93 09 28 V,* Curv Radial velo ft ORIONIS 1242 1908. Jan. 20. G. M. T. 15 h 15 m ature . . . city . 4- 2J 7 1KETT. b. Observed by \ T q p Measured by / J ' b - FLAJ Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev 1 " Velocity. 2 1 54-7430 54 0320 54-0078 53-4467 2 3 2 53-1110 45 2740 45-2692 2783 0396 + 41-34 0078 4467 0380 0444 + 43 76 50-75 Weighted mean + 44 22 V a . ... -17 93 09 28 Vrf Curva Radial veld ft ORIONIS 1242 1908. Jan. 20. G. M. T. 15 h 15 m ture jity + 25 9 KBIT. c. Observed by' \ T p Measured by JJ- ** Wt. Mean of Settings. Corrected Star Settings. Disp* in rev ns Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp 4 in rev ns Velocity. 2 1 3 2 54-7111 54-0022 53-9678 53 4174 2 2 2 53 0790 45-2307 45 2378 2655 0268 + 27-97 9990 4500 0292 0477 +33-61 + 54-55 Weighted Rad 25o21 mean +37 98 93 09 V a . -17 V Velocity 2 2 2 2 54 7244 54-0125 53-9841 53-4295 2 3 53-0980 45-2705 45-2622 2820 0433 + 45-1! oooo 4445 0302 '0422 + 34-76 48-26 Weighted mean +43'09 V a -17-93 Vd - '09 Curvature '28 Radial velocity +24'8 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 289 1908. Jan. 20. G. M. T. 15" 47 m p ORIONIS 1244 a. Observed by "I T d D . Measured by J J -S- PLASKKTT - Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev 118 Velocity. 2 54-7275 2 53-0998 > 54-0201 3 45-2686 2811 0424 + 44 25 3 53'!>956 0050 0358 + 41 20 2 45-2611 2 53-'J3>5 4410 0387 43-11 Weighted mean .... V a Vd Curvature . + 42-82 -17-93 09 - '28 Radial velocity +24'5 $ ORIONIS 1244 6. 19U8. Jan. 20. Observed by | T s PL , SKKTT G. M. T. 15" 47 m Measured by)' ' Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Setting.*. Corrected Star Settings. Disp' in rev 01 Velocity. 2 2 3 54-7310 54-0209 53-9910 53-1264 2 3 2 53-1050 45-2620 45-2632 2723 0336 +35-07 9990 4340 0292 0317 + 33 61 36-25 Weighted mean +34'82 V a -17-93 V d - -09 Curvature.... - '28 Radial velocity +16'5 ORIONIS 1244 e. 1908. Jan. 20. Observed by\ T p .__ G. M. T. 15" 47'" Measured by j j ' S ' PLASK TT- Wt. Mean of Settings. Corrected Star Settings. Disp' in rev 1 " Velocity. Wt. Mean of Settings. Corrected Star . Settings. Disp' in rev" 8 Velocity. 2 2 3 2 54-7336 54-0231 54-0019 53-4S95 2 3 2 53-1058 45-2684 45-2638 2780 0393 + 41-02 0090 4460 0392 0437 + 45-11 49-97 Weight Rat 25a 21i ed mean h 44-75 V a .. -17 93 - -09 - -28 Vd Curvature lial velocity +26-4 290 DEPARTMENT OF THE INTERIOR 1908. Jan. 20. - G. M. T. 15 h 53'" 3 ORIONIS 1245 , 9-10 EDWARD VII., A. 19K Observed by\ T p Measured by/ d ' te ' ^ LASKETT - Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 3 Velocity. Wt. Mean of Settings. Corrected Star ' Settings . Disp 4 in rev ns Velocity. 2 54-7272 2 . 53-1018 1 54 '0156 3 45-2650 2763 0376 +39-24 3 53 "9966 '0090 '0392 -f-45'12 2 45-2622 2 53-4315 4430 0407 46-54 Weighted mean Curvature. -17-93 - -09 - "28 +43"27 Radial velocity. + 25.0 ,3 ORIONIS 1245 b. 1908. Jan. 20. Observed by \ r a p ._ G. M. T. 15 h 53 m Measured byj U- Wt. Mean of Settings. Corrected Star Settings . Disp 1 in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings . Disp' in rev" 8 Velocity. 2 2 3 * 2 54-7467 54 0342 54-0184 53-4430 2 3 2 53 1202 45-2774 45-2760 2750 0363 + 37 '89' 0074 4340 0376 0337 + 43 27 38-53 Weight Rao ORIONIS 124J 1908. Jan. 20. G. M. T. I5 h 53 m ^d mean + 40-07 V -17-93 - '09 - -28 Curvature . . ial velocity + 21.8 )C. Observed by\ , g p LA Measured by / ' Wt. Mean of Settings. Corrected Star Settings . Disp' in rev ns Velocity. Wt. Mean of Settings. Corrected Star Settings . Disp 1 in rev" 8 Velocity. 2 54 '7458 2 53-1193 2 54-0321 3 45 2750 2740 0353 +36-84 3 54-0084 '0034 0336 j-38'67 2 45-2742 2 53-4436 4390 0367 41-97 Weighted mean +38'81 Va -17-93 Vd - -09 Curvature "28 Radial velocity + 20'5 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a ORIONIS 1249 . 291 1903. Jan. 20. Observed by \ T ^ PT.,,,-, G. M. T. 16 h 37 m Measured by/ J ' b> FLASK Wt. Mean of Settings. Corrected Star Settings. Dispt in rev ns Velocity. Wt. Mean of Settings. Corrected Star Settings . Dispt in rev n! Velocity. 2 2 3 2 51-7444 54-0334 54-0037 53-4376 2 3 2 53-1200 45-2714 45-2782 2663 0291 +30-37 9987 . -4320 0289 0297 + 33-26 33-96 Weighted i Radial ' /3 ORIONIS 12 V, 1908. Jan. 20. G. M. T. 16 h 17 lean . . -- +32 35 10 3KETT. V a . 17-93 09 28 + 1< Vd Curvature T elocitv r o. Observed by \ T a p Measured by j J " b ' PLA Wt. Mean of Settings. Corrected Star Settings. Dispt in rev" 8 Velocity. Wt. Mean of Settings. i Corrected Star Settings. Dispt in rev ns Velocity. 2 1 3 2 54 7364 54-0227 54-0078 53-4296 2 2 2 53 1070 45-2606 45'2G24 2715 0327 +34 13 0138 4350 0440 0327 + 50 64 37 40 Weighted 11 Radif ORIONIS 1247 1908. Jan. 20. G. M. T. 16 h 17 m lean +42 14 V a 17 93 09 28 Va- Curvature . tl velocity ... . -1-2.' J-8 JKETT. b. Observed by\ T p Measured by J J ' b - FLAS Wt. Mean of Settings, Corrected Star Settings. Disp 4 in rev ns Velocity. Wt. Mean of Settings. Corrected Star Settings. Dispt in rev"' Velocity 9, 54 7274 2 53-0931 \ 54-0096 ... .* .... 3 45 2634 2794 0397 + 41-43 3 53-9963 0135 0437 + 50-29 2 45-2577 \ 2 53 4377 4557 0534 61-06 Weighted mean +49'66 V a -17-93 Va- - -09 Curvature . '28 Radial velocity +31 '3 292 DEPARTMENT OF THE INTERIOR 1908. Jan. 20. G. M. T. 16 h 17 n ,8 ORIONIS 1247r. 9-10 EDWARD VII., A. 191t Observed byl T <. p Measured by f Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 9 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. 2 1 1 1 54-7402 54-0234 53 9742 53 4253 2 3 2 53-1140 45-2624 45-2770 2660 0273 .28-4, 9760 4260 0071 0237 + 8 17 27-10 Weighted mean . V a Curvature. Radial velocity . . -17-9.-! 09 - -28 + 24-15 + 5-8 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 293 1908. Jan. 20. G. M. T. 16 h 27" 13 ORIONIS 1248 c. Observed by Measured by Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 9 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" s Velocity. 2 54 '7472 2 53 1250 1 54 0420 3 45-2991 2891 '0504 + 52 60 2 54-0294 0174 0505 + 58-12 2 45-2836 2 53-4593 4493 0470 53-75 Weighted mean +54'51 V a -17-93 Vd.-.. "09 Curvature .... - " 28 Radial velocity. + 36-1 1908. Jan. 20. G. M. T. 16 h 37' ORIONIS 1249 h. Observed by\ T o p IAairFTT Measured by } J - S ' ^ LASKETT - Wt. Mean of Settings. Corrected Star Settings. Disp' in rev ns Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp 4 in rev" 9 Velocity. 2 54 ' 7478 2 53 '1232 2 54-0356 3 45-2788 2680 0293 + 30-58 2 54-0084 0004 '0306 + 35'22 45 '2844 2 53-4450 ' 4355 0342 39-11 Weight \ C Radial j8 ORION 1908. Jan. 20. G. M. T. 16 h 37'" ed mea T a n.. + 34-J (4 -17 93 09 28 j . _ /urvatu velocitj IS 124 re T + 16 KKTT. Sc. Observed by\ T o p Measured by / J - b - FLA6 Wt. Mean of Settings. Corrected Star [Settings. hPret Velocity. Wt. Mean of Settings. Corrected Stir Settings. Disp' in rev n " Velocity. 2 2 2 2 54-7362 54-0240 53-9998 53-4435 2 3 53-1092 45-2725 45-2704 2760 0373 +38-93 0040 4473 0342 +39-36 0451 51-57 Weight 1 C Radial ed mea r a a +42-6 6 -17- - )3 99 28 Td /urvatu velocitj re. . T + 24-5 5 294 1908. Jan. 27. G. M. T. 15 h 30" /3 ORIONIS 1285 a. 9-10 EDWARD VII., A. 1910 Observed by J. S. PLASKETT. Measured by W. E. HARPER. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected- Star Settings. Disp' in rev" 8 . Velocity. 2 56 '2642 2 54-8480 2 H 56-2207 55-S517 2768 "4083 0470 0539 + 35-17 39 '88 i 1 42-3191 42-3130 3130 0520 + 32 61 Weighted mean +35'81 V a -20-08 - -16 c Rad j8 ORIONIS 11 1908. Jan. 27. G. M. T. 15 h 30 m urvature 30 al velocity. 5856. IV +15 3 KETT. RPKR. bserved by J. S. PLAS [easured by W. E. HA Wt. Mean of Settings. Corrected Star Settings. Dispt in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Dispt in rev" 8 Velocity. 2 2 2 1 57-3371 56-2462 56-1983 55-3500 2 2 H 54-8307 42-3000 42 3092 3283 0673 + 42-20 2724 4241 0426 0697 + 31-88 51-53 Weighted mean +39'72 V a -20-08 Vd - -16 Curvature... '30 Radial velocity +19'2 1908. Jan. 27. G. M. T. 15 h 30". j8 ORIONIS 1285 c. Observed by J. S. PLASKETT. Measured by W. E. HARPEK. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity 2 57-3127 2 54-8130 2 56-2255 2 42 2834 . 2 2 56-1773 55 3222 2718 4147 0420 0603 +31-43 44-62 11 42-2936 3293 0683 + 4283 Weighted mean +39'38 V a -20-08 Vd - -16 Curvature... . - '30 Radial velocity + 17 9 m REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 205 1908. Jan. 27. G. M. T. 16 ! '09 m . /3 ORIONTS 1286 a. Observed by J. S. PLASKKTT. Measured by W. E. HARPER. Mean of Settings. Corrected Star Settings. Disp' in rev" 9 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev ns Velocity. 57 '2727 2 54-7770 56-1937 2 42-2466 56-1589 55-2850 289 4130 0571 0586 + 42-73 43-36 H 42-2512 3227 0617 + 38'6 Weighted mean +42'20 V a -20-03 Vd - '19 Curvature - '30 1908. Jan. 27. G. M. T. 16 h 09" Radial velocity +21'3 /3 ORIONTS 1286 I Observed by J. S. PLASKETT. Measured by W. E. HARPER. Mean of Settings. Corrected Star Settings. Disp 4 in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Dispt in rev" 8 Velocity. 57'3533 2 54-8539 56-2652 2 42-3240 56:2297 55-3552 2848 4074 0550 0530 + 41-16 39 21 I* 42 3241 3192 0582 + 36-50 Weighted mean +39 17 V a -2008 Vd - '20 Curvature . . - ' 28 Radial velocity + 18' 7 1908. Jan. 27 G,M. T. (3 ORIONIS 1286 c. Observed by J. S. PLASKETT. Measured by W. E. HARPER. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Comcted Star Settings. Disp' in rev" 8 Velocity. 2 57-3761 2 54-8777 2 56-2915 2 42-3443 2 2 56-2610 55 38% 2S98 4175 0600 0631 + 44 90 46-68 2 42-3548 3296 0686 +43-02 Weighted mean +44'87 V a -20-08 Vd - '19 Curvature . . . . - ' 30 Radial velocity 24-3 296 DEPARTMENT OF THE INTERIOR 1908. Jan. 27. G. M. T. 17 h 17'" (3 ORIONIS 1289 a. 9-10 EDWARD VII., A. 1910 | Observed by J. S. PLASKETT. Measured by W. E. HARPER. Wt. Mean of Settings. Coi rected Star Settings. Disp 1 in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. ' Disp 1 in rev 1 Velocity. 2 { 7 '3477 2 54 '8500 2 56 '2633 3 42 '3258 3168 0558 + 34'99 2 56-2241 1671 0627 + 46-92 2 42-3286 U 55-3630 3070 0474 35-07 Weighted mean + 38 ' 62 V a -20-08 V d -19 Curvature . . - '30 Radial velocity +18'1 /3 ORIONIS 1289 I,. 1908. Jan. 27. G. M. T. 17 h 17'" Observed by\ T a p IA< , KFTT Measuredby/ J - b Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev 119 Velocity. 2 1 3 2 57-3801 56-2921 56-2507 55-3890 1 2 3 2 54-8794 42-3664 42'3584 3275 0665 + 41 70 2780 4155 0482 0611 + 36'07 45 21 Weight \ I ,ed mean . . 1-40-46 V a -20-08 19 30 Curvatu ladial velocit re v. +19-9 1908. Jan. 27. G. M. T. 17 h 17"' /3 ORIONIS 1289 e. Observed by | T p .,.,.,, Measured by J J ' b " ASKBTT. Wt. Mean of Settings. Corrected Star Settings . Disp 1 in rev ni Velocity. Wt. Mean of Settings. Corrected Star Settings . Disp' in rev" 8 Velocity. 2 57-3608 2 54 ' 8612 2 56-2675 3 42'3602 3425 0815 + 51-11 3 56-2378 2900 '0602 + 45'05 2 42 '3378 2 55-3721 4200 0656 48-54 Weighted mean ..................... + 48 '19 V a - ... - 20-08 Curvature '30 Radial velocity + 27'8 . REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a ft ORION IS 1290 , litOS. Jan. 27. Observed by ;. M. T. 17 h 28 m Measured by 297 Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. t Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 9 Velocity. o 57 3519 2 54-8582 2 56-2658 2 42-3268 '3156 0546 -f 34'24 3 56-2260 2800 0502 + 37-56 2 42 3308 Weighted mean + 36'28 V a - 20-08 Vd "19 Curvature... - '30 Radial velocity + 15' 6 1908. Jan. 27. G. M. T. IT 1 ' 2S' ORION IS 1290 L Observed by Measured by P rA . KI , TT ^ FLASKETa - Wt. Mean Corrected of Star Settings. Settings. Disp' in rev"' Velocity. Wt. Mean of Settings. Corrected Star Settings . Disp' in rev" 3 Velocity. 2 57-3527 , 2 54-8536 2 56-2622 . . . 2 42 '3223 3190 0580 + 36-37 3 56-2360 ! '2940 0642 + 48-04 2 42-3224 9 55-3534 I 4074 0530 39-21 ! Weighted mean + 42'18 V a - 2C-08 V d -19 Curvature '30 Radial velocity. + 21-6 1908. Jan. 27. G. M. T. 17 h 28'" ORIONIS 1290 e. Observed by Measured by Mean Wt. of 57-35% 56-2706 56 2320 55-3704 Corrt'Cted Star Settings . Dispt in rev" 3 Velocity. Wt. 2 . . . 3 2810 4i:;4 0512 0590 + 38-31 43-65 2 Mean of Settings. 54-8680 42-3490 42-3368 Corrected Star Settings . 3313 Disp* in rev" 9 0503 Velocity. + 31 54 Weighted mean + 36 70 V a - 20-08 Vd '19 Curvature... - '30 Radial velocity. + 298 9-10 EDWARD VII., A. 1910 1908. Mar. 20. G. M. T. ll h 51 m ORIONIS 1405. Wt, Mean of Settings. Corrected Star Settings. Disp' in rev ns Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp 1 in rev n Velocity. o 63-3300 2 58-7869 2 61-3502 2 36-2090 2170 1265 + 44 '48 9 61 '31 21 3064 1259 + 52-05 2 36-1858 59-7292 7236 1271 52-00 Weighted mean +48'37 V a -24'86 Vd - -14 Curvature '28 Radial velocity +23 1 1908. Mar. 20. G. M. T. 12 h 07 m j8 ORIONIS 1406. Observed byl T Measured by J J - Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp 1 in rev" 8 Velocity. 2 63 '3238 2 58 '7846 2 61'3466 li 36-2180 2235 1330 + 46'76 2 ' 61-3115 3095 1290 + 53-33 2 36-1886 ii 597150 7122 1157 47-33 1908. Mar. 20. G. M. T. 12 h 21 Weighted mean + 49 50 V a -24-86 Vd '14 Curvature "28 Radial velocity + 24'3 ORIONIS 1407. Observed by\ T Q p ., Measured by. I Jl b ' Fl - ASKETT - Wt. Mean of Settings. Corrected Star Settings. Disp' in rev 1 Velocity. Wt. Mean of . Settings. Corrected Star Settings. Disp 1 in rev" 8 Velocity. 2 63-3248 2 58 '7786 2 61-3441 2 36-1872 '2090 '1185 + 41-66 3 61-2936 2941 1136 + 46'% 2 36-1721 u 59-7240 7260 1295 52-98 Weighted mean +46'72 V a -24-86 Vd -14 Curvature... - '28 Radial velocity - 21 4 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a j8 ORIONIS 1408. 299 1908. Mar. 20. Observed by) T s p ..,__, G. M. T. 12 h 32'" Measured by/ J> &1 Wt. Mean of Settings. Corrected Star Settings. Disp' in rev Velocity. Wt. Mean of Settings. Corrected Star Setting?. Dispt in rev 115 Velocity. 2 2 2 63 3338 61-3533 61-3036 59-7392 2 2 M 58-7904 36-2218 36-1832 23i5 1410 + 49-58 2946 7302 1141 1337 +47-17 54-70 Weighted mea Radial j8 ORIONIS 14C 1908. Mar. 20. G. M. T. 12 h 46 m n -4- fin 15 9 v a 24-86 14 28 + 24 Curvature velocity >9. Observed by\ T T> r .. Measured by/ J '- rLA ^ r t Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. D'sp' in rev" 3 Velocity. 9 63 3224 1 58'7782 2 61 3452 2 36 2226 '2365 1460 +51-33 > 61 3028 3048 1243 + 51-39 2 36'lSOl H 59 7364 7390 1425 58-30 Weighted mean -53'25 V a -24'86 Vd 14 Curvature. . . - '28 Radial velocity +28'0 1908. Mar. 20. G. M. T. 13 h 00 m j8 ORIONIS 1410. Observed by\ T Measured byf j - Mean of Settings. Corrected Star Settings. Disp 4 in rev" 1 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 9 Velocity. 63-3280 2 58-7856 61-3492 2 36 2229 2265 1360 + 47'82 61-3050 * '3010 1205 + 49-81 2 36-1906 59 7178 7136 1171 47-91 Weighted mean V* ...... Curvature . . -24-86 14 - '28 Radial velocity +233 300 DEPARTMENT OF THE INTERIOR 1908. March 20. G. M. T. 13 h 12 m ORIONIS 1111. 9-10 EDWARD VII., A. 191O Observed i>y J. S. PLASKETT. Measured by W. E. HARPER. Wt. Mean of Settings. Corrected Star Settings. Oisp' in rev ns Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev na Velocity. e 63 1088 2 58-5R47 3 61 ' 0842 61-2989 + '1184 + 48'95 2 35'! 15'. 10 H 59-5095 59-7259 1294 52-94 2 0-9851 36' 2203 1298 + 45-64 Weighted mean +48'85 V a -24-86 Vd -17 Curvature '28 Radial velocity +23'5 ft ORIONIS 1412. 1908. March 20. Observed by J. S. PLASKETT. G. M. T. 1.3 h 27' n Measured by W. E. HARPER. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp 1 in rev" 8 Velocity, 2 3 2 63-1178 61-0974 59-5242 2 2 2 58-5736 35-9727 36-0000 61-3005 59-7314 1200 1349 + 49-60 55-18 36-2215 1310 + 46-06 Weighted n V lean + 50 1 8 > 4'86 17 28 Va Gun 'ature Radial velocity +24'9 1908. March 20. G. M. T. 13 h 47 ft ORIONIS 1413. Observed by J. S. PLASKKTT. Measured by W. E. HARPED Wt. Mean of Settings. Corrected Star Settings. Disp' in rev"* Velocity. Wt. Mean f Settings. Corrected Star Settings. Di I-' in R.-v - Wi c ty. 2 63-3873 2 58-8412 3 1| 61-3699 59-7810 61-3083 59-7205 1278 1240 + 52-83 50-73 2 2 36-3010 36-2495 36-2455 1550 + 54-W Weighted mean +52'86 V - -24-86 V d -17 Curvature - '28 Radial velocitv +27'5 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 301 1908. March 20. G. M. T. 13 h 57 m /iJORIONIS 1414. Observed by J. S. PLASKKTT. Measured by W. E. HARPER. Wt. Mean . f Settings. Corrected Star Settings. Disp in rev 118 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. 2 63 "3927 2 58-8485 3 2 61 3695 59 '7945 61-3015 59-7270 1210 '1350 + 50-02 53'38 2 2 36-2981 36 2572 36 2350 1445 + 54-40 Weighted mean...: +52'23 V a -24-86 Va- - -17 Curvature '28 Radial velocity +26'9 1908. March 24. G. M. T. 12 h 03' ft ORION IS 1426. Observed by J. S. PLASKETT. Measured by W. E. HARPER. Wt, Mean of Settings. Corrected Star Settings. Disp< in rev" s Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev"' Velocity. 2 63-3J55 2 58-7935 2 1.', 61-2946 59 7192 61 2780 59-7040 0975 '1075 + 40-35 43-98 H 2 36-1955 36-1592 36-2300 1395 + 49-05 i Weighted mean + 44 "05 V a -24 36 Va- 16 Curvature - "28 Radial velocity +19'2 1908. March 24. G. M. T. 12 h 15" ORIONIS 1427. Observed by J. S. PLASKKTT. Measured by W. E. HARPER. Wt, Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings, Disp' in rev n " Velocity. 2 63-3382 2 58'7912 2 1 61-2918 59-7208 m-2798 59-7098 0993 1133 + 41-09 46'35 2 2 36-2085 36-1682 36-2340 1435 + 50-45 Weighted mean +45'89 V a -24-36 Vd - -16 Curvature.... - '28 Radial velocity + 21 " 1 302 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 j /3 ORION IS 1428. J908. March 24. Observed bj 1 T a Pr AC1K -,, TT G. M. T. 12 h 23 m Measured by / d Wt. Mean of Settings, Corrected Star Settings. Disp' in rev" 9 Velocity. Wt. Mean of Settings. Corrected Star Settings. ' Disp' in rev"' Velocity. 2 2 U 63-3148 61-2682 59-6971 2 2 2 58-7726 H6-1838 36-1522 6i-2772 59-7060 0967 1095 + 40'01 44-80 36- 2255 | '1350 -^47-47 Weighted mean +44'03 V a -24-36 Vd - -16 Curvature - "28 Radial velocity +19'2 1908. March 24. G. M. T. 12 h 36 m /30RIONIS 1429. Observed by i Measured by/ ' Wt. Mean of Settings. Corrected Star Settings. Dispt in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp 1 in rev" 8 Velocity. 63'3133 2 58'7619 61-2675 59 '6988 61-2825 59 ' 7160 1020 1195 + 42-21 48 '89 2 2 36-1559 36 '1282 36-2215 1310 + 46-06 Weighted mean + 45 " 43 V a -24-86 Vd - -16 Curvature. - '28 Radial velocity +21'6 1908. March 24. G. M. T. 12 h 42 /3 ORIONIS 1430. Observed byl T Measured by / J< Wt. Mean of Settings. Corrected Star Settings. Dispt in rev"' 1 Velocity. Wt. Mean of Settings. Corrected Star Settings. Di.sp' in rev na Velocity. 63 '3288 2 58-7792 2 14 61-2808 59 ' 7068 61-2795 59 ' 7075 0995 '1110 + 41-17 45-41 a 2 36-1830 36-1581 36-2190 1285 + 45-18 Weighted mean +43'65 V a -24-36 Vd - '16 Curvature. . '28 Radial velocity. . . + 18 ' < REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 303 1908. March 24. G. M. T. 12 h 52 ra /3 ORIONIS 1431. Observed by) T o T> Measured by } J - S - PLASKETT - Wt. Mean of Settings. - Corrected Star Settings. Dispt in rev ns Velocity. Wt. Mean of Settings. Corrected Star Settings. Dispt in rev" 8 Velocity. 2 63-3248 2 58-7802 2 H 61-2775 59-6884 6P2775 59-6890 0970 0925 + 40-14 + 37-84 2 2 36-1932 36-1520 36-2350 1445 + 50-81 Weighted mean +43'39 V a -24-36 Va - '16 Curvature ... " 28 Radial velocity . + 18-6 1908. March 24. G. M. T. IS* 16 /3 ORIONIS 1433. Observed by\ T s P IA( , KFTT Measured by/ J ' b ' FLASKETT - Wt. Mean of Settings. Corrected Star Settings . Disp* in rev ns Velocity. Wt. Mean of Settings. Corrected Star Settings . Dispt in rev" 9 Velocity. o 63-3394 - ? 58-7740 2 n 61-2791 59-6956 61 2816 59 7020 ioii ' 1055 + 41-84 43-16 2 2 36-1666 36-1490 36-2106 1201 + 42-23 Weighted mean + 42 34 V a - 24-36 Vd - '16 Curvature. . . ' 28 Radial velocity .... + 17 ' 5 /3 ORION CS 1434. 1908. March 24. Observed by ) T q p G. M. T. 13 h 32 m Measured by/ J ' S< * aA8K Wt. Mean of Settings. Corrected Star Settings . Di.sp* in rev 118 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. 2 2 1 63-3430 61-2968 59-7385 2 1 2 58-7969 36-2018 36 174-4 61-2790 59 7215 0985 1254 + 40-76 51-30 36-2210 1305 + 45-88 Weighted Rac 25a 22 mean + 44-08 V a - 24-36 16 28 V d Curvature lal velocitv f- 19'3 304 DEPARTMENT OF THE INTERIOR 1908. March 24. G. M. T. 13" 39" 3 ORIONIS 1435. 9-10 EDWARD VII., A. 1910 Observed by ) T ^ p .,,.___, Measured by J J ' S< L LA8KETT - wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings . Disp' in rev"" Velocity. 2 63-3082 2 58'7515 2 1 61-2508 59-6761 6i-2727 59-7034 0922 1069 + 38-15 43-32 li 2 36-1366 36-1180 36-2126 1221 + 42 93 Weighted mean + 40" V fl - 24-36 Vd 16 Curvature.... - '28 Radial velocity. . + 16 ' 1 1908. March 24. G. M. T. 13 h 48" ORIONIS 1436. Observed by\ T ^ p ^ KV TT Measured byj I J> b ' Fl - ASKKTT - Wt. Mean of Settings. Corrected Star Settings . Disp in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings . Disp* in rev" 8 Veloci ty. 2 63-3496 2 58-8030 2 14 61 2902 59-7106 61-2762 59 '6876 0957 0921 + 39-60 37 ' 68 ? 36-2066 36-1692 36-2310 1405 + 49'40 Weighted mean +41 96 V - 24-36 Vj - -16 Curvature. . . ... - '28 Radial velocity +17'2 1908. March 24 G. M. T. 13 h 5-6 j8 ORIONIS" 1437. Observed by \ T ^ p .,,_, Measured by / J - b ' "******< Wt. Mean of Settings. Corrected Star Settings. Disp' in rev"' Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. 2 63 3020 2 58 '7548 ! 4 61-2558 59-6798 61-2800 59-7050 0995 1085 + 41-17 44-39 2 2 36-1466 36-1222 36-2180 1275 + 44-88 Weighted mean +43'51 V - 24-36 V d - -16 Curvature.. . . - '28 Radial velocity. + 18-7 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 305 1908. March 24. G. M. T. 14 h 07" ft ORIONIS 1438. Observed by ) T p ..,., Measured by/ J ' b ' ^ LASKETT - Wt. Mean of Settings. Corrected Star Settings. Disp 4 in rev" 9 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp 1 in rev ns Velocity. 2 63-3504 2 58-8022 li 61-3018 59 7345 61 2780 59-7125 0975 1160 + 40-54 47'46 H 2 36-2016 36-1784 36 2170 1265 4-44-48 Weighted mean + 43 75 Va - 24-36 Va '16 Curvature.... - 28 Radial velocity + 18 1908. March 30. G. M. T. 12 h 19" IB ORIONIS 1439. Observed by \ T p A^CPTT Measured byj j ' h ' FLASKETT - Wt. Mean of Settings. Corrected Star Settings. Disp' in rev ns Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 V elocity. ?, 63-3002 2 58 '7534 3 H 61-2444 59-6804 2993 7304 0870 1066 + 35-86 43-48 2 2 36-1192 36'1146 1568 1087 + 38-11 Weighted mean +38'31 V - 23-39 Vrf -21 Curvature... - '28 Radial velocity + 14 ' 4 13 ORIONIS 1440. 1908. March 30. Observed by \ T Q Vr Al G. M. T. 12" 29- Measured b y } J ' S " P ^KETT. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev"' Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. 2 2 H 63-3356 01-2894 59-6994 2 2 2 58-7895 36-1602 36-1642 r 3087 7132. 0964 0894 + 39-74 40-54 1480 0999 +35-02 Weigh te V V Cv Radial > 25a 22 d mean +38 24 23-39 21 28 t . irvaturt elocity > + 14- 4 306 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 1908. Mar. 30. G. M. T. 12 h 38 m /S ORIONIS 1441. We. Mean of Settings. Corrected Star Settings. Disp* in rev n8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. 2 63 '4150 2 58'8640 2 1 61-3622 59 '7768 3042 7148 0919 0910 + 37-88 37-12 $ 36-2522 36-2426 1620 1139 + 39-93 Weighted mean +38'39 V a -23-39 Vd -21 Curvature... - '28 Radial velocity + 14 ' 5 1908. Mar. 30. G. M. T. 12 h 49 m j8 ORIONIS 1442. Observed by\ T Measured by/ J ' Wt. Mean of Settings. Corrected Star Settings. Disp* in rev na Velocity. Wt. Mean of Settings. Corrected Star Settings. Dispt in rev 118 i Velocity, j 2 63 '3596 2 58-8129 2 14 61-3220 59-7322 3175 7220 10f>2 0982 + 43-36 40-06 11 2 36-1715 36-1666 1572 1091 + 38-25 i Weighted mean +40'84 V fl -23-39 Vd - -21 Curvature. . . - ' 28 Radial velocity + 17 " 1908. April 3. G. M. T. 12 h 16 m ORIONIS 1448. Observed by I T PlAS . KIi , TT Measured by f J " b> ^ LASKETT - Wt. Mean of Settings. Corrected Star Settings. Dispt in rev" 9 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev ns Velocity. 2 63 3573 2 58'8206 2 l| 61-3387 69 7S41 61-3037 59-7160 1232 '1195 + 50-93 48 '89 i 1 36-2340 36-2156 36-2126 1184 + 41 63 Weighted mean +48'02 V fl -2269 Vd - '16 Curvature. . - "28 Radial velocity + 24 ' 9 . REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 307 1903. April 3. G. M. T. 12 h 28 m 13 ORIONIS 1449. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev ns Velocity. Wt. Mean of Settings . Corrected Star Settings . Disp' in rev ns Velocity.. 2 63-3266 2 58-7829 2 H 61-3045 59-7338 61-3024 59-7320 1219 1355 + 50-39 55-43 2 2 36-2068 36-1722 36-2285 1380 +48-52 Weighted mean +51'08 V a -22-69 V d -16 Curvature. . . - - 28 Radial velocity .... +27 "9 908. April 3. G. M. T. 12 h 40 m ORIONIS 1450. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 3 Velocity. Wt. Mean of Settings. Corrected Star Settings. Dispt in rev ns Velotity. 2 63-3216 2 58-7768 2 14 61 3092 59-7388 61-3124 .>! 742* 1319 1463 + 54-53 59-85 1 2 36-2098 36-1714 36-2325 1420 +49.93 Weighted mean +55'28 V a -22-69 Va- - '16 Curvature... "28 Radial velocity +32'2 1908. April 3. G. M. T. 12" 53" /3 ORIONIS 1451. Observed by "I T Measured by[ J ' Wt. Mean of Settings. Corrected Star Settings. Disp' in rev 1 Velocity. Wt, Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. 2 63-3301 2 58-7860 2 H (>!. W62 59-7310 61-3007 59-7260 1202 1295 + 49-69 52-98 !' 36-2164 36-1830 -36-2275 1370 + 48-47 Weighted mean . . .. +50'22 V a -22-69 V d "16 Curvature... - '28 Radial velocity. + 27-1 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 1908. April 4. G. M. T. 12 h lit'" ORIONIS 1457. Observed by\ T o p Measured byP' b< FLASKim - Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. " i ~ iS. Veloei^ 2 63-3698 i 2 58-8305 j 3 2 61-3515 59-7708 61-3069 59-7224 1264 125!) + 52-25 51-51 2 , 2 36-2996 36-2358 36-2580 1638 -5759 Rad /5 ORIONIS 14E 1908. April 4. G. M. T. 12 h 28 m V a . . -22-41 22 - -28 Vrf. Curvatu ial velocity. re. h29'9 ,KETT. >8. Observed by\ T ^ ,, Measured by/ J - b ' FLAS Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev 115 Velocity! 2 2 14 63 3566 61 3314 59-7500 2 H 2 58-8112 36-2475 36-1956 61 3004 59-7196 ii99 1231 449-57 50-36 36-2460 1551 + 54-6?; Weighted mean . . , 1-51-34 V a -22-40 23 - '28 Va Curvatui e Radial velocity + 27 ' 4 P ORIONIS 1459. 1908. April 4. Observed by \ T PrA6 . KB . TT G. M. T. 12" 38-" Measured by j 1 J ' h ' FLASKE "- Wt. Mean of Settings. Corrected Star Settings. Disp' m rev 1 " Velocity. Wt. x Mean of Settings. Corrected Star Settings. Disp* in rev nil Velocitj 2 3 n 63-3648 61-3354 59-7F62 2 H 2 58-8227 36 2782 36-2194 61-2944 59 71EO 1139 1185 + 47'09 48-47 36-2500 1625 + 57-K i Weight ed mean h 49-93 v a . -22 40 23 - '28 V d Curvatu re Radial velocity +27 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 309 1908. April 13. G. M. T. 12" 10' |8 ORIONIS 146<. Observed by { T s Measured by J J ' \ Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 9 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. 63'3830 58-8337 61 '4037 36-1867 a 61-3453 59-7340 3210 7090 1087 1852 + 44-81 34-75 1 36-2037 1690 1209 + 42-38 Weighted mean +4203 V a ... -2023 Vd - -28 Curvature . . - '28 Eadial velocity +21 '3 /3 ORIONIS 1470. 1908. April 13. Observed by\ T PlASKETT G. M. T. 12" 22 m Measured by J J ' ~ r t. Mean 1 Corrected of Star Settings. Settings. Disp' in rev"" Velocity. Wt. Mean of Settings. Corrected Star Settings. Dispt in rev" 8 Vel ocity. 63 '3425 ! 58-7861 36-1305 36-1485 61-3570 ' 61-3030 -3230 59 7213 7440 1107 1202 + 45-63 49-03 1700 1219 +42-73 Weighted mean + 45-75 -20-23 - -25 - -28 V,* .. Curvature Ra /3 ORIONIS 1' 1908. April 13. C. M. T. 12" 34"' dial velocity 425-0 3KKTT 171. Observed by \ T Q p, . Measured by J J< b ' r Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 9 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp 1 in rev" 9 Velocity 63-3504 58-7960 61-3650 36-1787 ?! 61-3036 59-7275 3156 7400 1033 1162 + 42-58 47-40 ii 36 1611 1876 1395 + 48-89 Weighted mean V (t 45'61 -202:? Vd ........... - -26 Curvature ..... "28 Radial velocity ... + 24 8 310 DEPARTMENT OF THE INTERIOR 1908. Sept. 7. G. M. T. 21 h 52" ORIONIS 1873. 9-10 EDWARD VII., A. 1910 Observed by J. B. CANNON. Measured bv J. S. PLASKETT. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. - Dispt in rev ns Velocity. 2 63 '3948 2 58-8286 2 61 '4080 2 36-1061 2 2 61-2458 59-6682 2498 6722 0008 0208 + 2-18 + 8'46 1 35-9859 9890 0168 -5'87 Weighted mean + 3'08 V +25-29 Vd + -09 Curvature . - '28 Radial velocity . + 28'2 /J ORIONIS 1874. 1908. Sept. 7. Observed by J. B. CANNON, G. M. T. 22 h 10 m Measured by J. S. PLASKETT. Wt. Mean of Settings. Corrected Star Settings. Dispt in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp 1 in rev ns Velocity 2 2 2 2 63-3952 61-40H4 61-2468 59-6584 2 2 1 58-8342 36-1037 35-9972 - 2495 6600 6050 0086 + 2'06 + 3-50 0025 0033 -i'ia Weight I ed mean h 1-99 1-25-2(1 1- -09 + 27-1 V a - Vd - Curvatu i,adial velocin re - -28 T. . . 1908. Oct. 13. G. M. T. 21 h 19" j3 ORIONIS 1935. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev ns Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp< in rev" 9 Velocit 2 63 '3! isn 2 58'8313 2 61-4043 o 36 1175 2 61-2224 2270 0175 -7-19 1 36-0062 9982 0076 -2'6 1 59-6723 6760 0210 + 8-54 Weighted mean ............. - 2'00 +20-66 Va Curvature. -05 '28 Radial velocity . +18'3 / REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 311 1908. Oct. 13. G. M. T. 21 h 48 m ft ORIONIS 1936. Melted b Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev ns Velocity. 2 63 3(526 2 58 '7965 2 61-3762 2 36-0878 3 H 61-1940 59-6216 2285 6576 0160 0062 -6-58 + 2-52 1 35-9778 oooo 0058 -2 03 Weighted mean - 3'27 V a +20-66 Vd - -10 Curvature .... - '28 Radial velocity .................. + 17 ' 1908. Oct. 13. (i. M. T. 22 h 19" ft ORIONIS 1937. Observed by 1 T r, Measured by/ J ' S ' Wt. Mean of Settings. Corrected Star Settings. Disp* in rev ns Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev ns Velocity. 2 63-3670 2 58-8030 2 61 3727 2 36-0830 2 1 61-2064 59-6093 2414 6423 0031 0091 -T27 3'70 i 36-9604 9875 0183 -6-50 Weighted mean - 2 '71 V ffl +20-65 Vd -14 Curvature... - '28 1908. Oct. 13. G. M. T. 22 1 ' 47" 1 Radial velocity +17'5 ft ORIONIS 1938. Observed by \ T o p .,-,, Measured by/ J ' b ' FLASKETT - Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 3 Velocity. Wt. Mean of SeUings. Corrected Star Settings. Disp' in rev 8 Velocity. 2 63-3806 2 58-8156 2 61 3922 2 3>'1048 3 2 61-2124 59-6301 * '2 '04 6386 0141 0123 - 5'FO 5-20 1 35-9790 9840 0218 - 7'62 Weighted mean ............ - 5 '90 Curvature.. Radial velocity . . . . 18 - '28 +20-65 + 14 3 312 DEPARTMENT OF THE INTERIOR 1908. Nov. 21. G. M. T. 18 h 24" p ORIONIS 1978. 9-10 EDWARD VII., A. 1913 Observed by I T c p Measured by/ J ' h - Fr ' Wt. Mean of Settings. Corrected Star Settings. Disp' in rev na Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. 2 P3 3468 2 58 7938 2 61'3628 2 36-1436 1 i 61-2132 59-6547 2282 6700 0159 0462 + 6-55 18-75 4 36-0681 0766 0285 + 9 95 Weighted mean + 10 ' 46 V a + 6'82 Vd -02 Curvature. . . ' 28 Radial velocity +17'0 1908. Nov. 21. G. M. T. 18 h 43"' /3 ORIONIS 1979. Observed by \ T Measured by/ J ' Wt. Mean of Settings. Corrected Star Settings. Dispt in rev" 8 Velocity. Wt. Mean of Settings. Correcte d Star Settings. Dispt in rev" 8 Velocity, 2 63'3061 2 58-7652 2 61 '3300 2 36-1120 li 61 ' 1662 '2174 \ 36-0187 0387 0106 + 3'7 1 59-6141 6591 0353 + 14-39 Weighted mean +10'83 V + 6 82 Vd -05 Curvature.... - "28 Radial velocity + 17 ' 3 1908. Nov. 21. G. M. T. 19 h 05'" /3 ORIONIS 1980. Observed by ) T o Measured by/ J ' b ' Wt. Mean of Settings. Corrected Star Settings. Disp* in rev 118 Velocity. Wt. Mean of Settings. Corrected Star Settings, Disp 4 in rev ns Velocity 2 63-3533 2 58 '7995 2 61-3671 2 36-1350 3 2 61-2382 59 6646 2480 6745 0357 0507 + 14-72 20-58 li 36-0917 1090 0609 + 21-34 Weighted mean + 18'08 V a .. + 6-82 Vd -09 Curvature. . . - ' 28 Radial velocity. + 24'5 / REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a ft ORIONIS 1981. 313 1908. Nov. 21. G. M. T. 19 h 33 Observed by } T p Measured by/ J> b ' * Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev ns Velocity. 2 63 '3651 2 58'8100 2 61 '3788 2 36-1536 3 H 61 2564 59-6711 2540 6700 0417 0462 + 17-19 18'75 1 36-1135 1120 0639 + 22 40 Weighted mean + 18'56 V a + 6-82 V* - 13 Curvature . . '28 Radial velocity + 25'0 ft ORIONTS 1984. 1908. Nov. 28. Observed by \ T p A KKT T G. M. T. 16 h 05 m Measured by/ J> &> 1 ft. 2 2 3 u Mean of Settings. Corrected Star Settings. Disp' in rev ns Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev n> Velocity. 63 3672 61-3818 61-2562 59-6454 2 2 2 58-8125 36-1472 36-1186 2518 -0395 6418 -0180 + 16-28 7-34 1236 0755 +26-47 Weig hted mean f 17-35 f 3'79 f '15 f21'0 V& Curvature - "28 Radial velocity ,3 ORIONIS 1985. 1908. Nov. 28. Observed by \ f ~ p G. M. T. 16 1 ' 34'" Measured by/ J - [ 2 2 3 2 Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev n8 Velocity. 63-4001 61-4112 61 2867 59-7043 2 2 li 58-8418 36 1728 36-1352 f, , 2527 6713 0405 0475 + 16-65 19 37 1155 0674 + 23-63 Weig ited mean + 19-10 3'79 10 V a + Vd + Curvature Radial velocity. . . - -28 + 22-7' 314 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 1908. Nov. 28. G. M. T. 17 h 08 m ft ORIONIS 1986. wt. Mean of Settings. Corrected Star Settings. Disp* in rev ns Velocity. Wt. Mean of Settings. Corrected - Star Settings. Disp* in rev" 8 Velocity. 2 63-3743 2 58-8170 2 61'3865 2 36-1450 3 1| 61-2439 59-6728 2340 6645 0217 0407 + 8-94 16-60 2 36-1220 1290 0809- + 28-3(5 Weighted mean + 16 '91 V a + 3 79 V<* + -05 Curvature... - '28 Radial velocity +20'5 1908. Dec. 1. G. M. T. 17" 53-* ft ORIONIS 1987. Observed by \ T q p .-___ Measured by/ J- S. PLABKBTT. wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev na Velocity. 2 63-3748 2 58 '8267 2 61-3934 2 36-2127 2 1 61-2490 59-6^24 2005 6385 0200 0420 + 8-33 17 13 1 36-1757 1573 0668 + 1'3'44 Weighted mean + 14 31 V a + 2'42 Vd. "04 Curvature.. - '28 Radial velocity + 16 ' 4 1908. Dec. 1. G. M. T. 18" 18 ft ORIONIS 1988. Sr^^felj. S. PLA.SKKTT. Wt. Mean of Settings. 63-3353 61 3527 61-2276 59 6515 Corrected Star Settings. 2515 6735 Dispt in rev"" 0392 0497 Velocity. + 16-16 20-27 Wt. Mean of Settings. 58-7876 36'l(i71 36-1272 Corrected Star Settings. 1123 Disp' in rev" 0643 Vel + 22-54 Weighted mean +18'78 V a + 2-42 V d - '09 Curvature . . - '28 Radial velocity + 20-9 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 315 1908. Dec. 1. G. M. T. 18 h 36" /3 ORIONIS 1989. Observed by"! T p ., Measured by/ J ' b ' ^ LASKETT - Wt. Mean of Settings. Corrected Star Settings. Disp* in rev n " Velocity. Wt. Mean of 1 Settings. Corrected Star Settings. Disp* in rev" 9 Velocity. 2 63-3437 2 58-7973 2 Gl'3587 2 36-1794 2 i 61-2166 59-6620 2335 6760 0212 0522 + 8-74 21-29 l\ 36-1287 1015 0535 + 18-75 Weighted mean .. +1406 V a . + 2'42 Vd - -12 Curvature - "28 Radial velocity + 16 ' 1 /3 ORIONIS 1990. 1908. Dec. 1. Observed by\ T s p G. M. T. 18 h 52 Measured by/ J ' h ' rLA8K Wt. Mean of Settings. Corrected Star Settings . Disp* in rev" 8 Velocity. Wt, Mean of Settings. Corrected Star Settings . Disp* in rev" 8 Velocity. 3 2 63 3478 61-3679 61-2397 59-6724 58-8000 36-1850 36-1648 2520 6830 0397 0592 + 16-36 24-15 1 1320 0839 + 29-41 Weighted mean . V-,. + 21-13 2-41 -4- Vd 16 - -28 Curva ture . . Radial velocity +23"! 1908. Dec. 5. G. M. T. 16 h 10 (3 ORIONIS 2003. Observed by J. B. CANNON. Measured by J. S. PLASKETT. Mean of Settings. 63-3465 61-3690 61-2456 59-6764 Corrected Star Settings . 6518, Disp 4 in rev ns 0410 .0553 Velocity. + 16-95 22-62 Wt. Mean of Settings. 58-8090 36-2298 36-2074 Settings . 1715 Dispt in rev" 8 0810 Velocity. + 28-48 Weighted mean +22'16 V a + "63 Vd .. + '10 Curvature '28 Radial velocity. +22'6 316 DEPARTMENT OF THE INTERIOR 1908. Dec. 5. G. M. T. 16 h 22 m ORIONIS 2004. 9-10 EDWARD VII., A. 1910 yvS^fy}*'*-^- Wt. Mean of Settings. Corrected Star Settings. Dispt in rev" 8 Velocity. Wt. Mean , Corrected of Star Settings. Settings . l)isp< in i-ev" 8 Velocity, 2 63 3170 2 58'7790 . 2 61-3390 2 36-1924 2 61.2216 2275 0470 + 19-43 1 36-1868 -1886 0981 + 34-49 i 59-6557 6610 0635 25-98 Weighted mean +24'67 V a + '63 Vd + '08 Curvature . . - '28 Radial velocity + 25 1 P ORIONIS 2005. 1908. Dec. 5. Observed by | T s PlASKFTT G. M. T. 16 h 38'" Measured by/ ' Wt. Mean of Settings. Corrected Star Settings , Dispt in rev" 8 Velocity. Wt. Mean of Settings. Corrected T) . t ^i-ir r, . in rev" 8 Settings. ; Velocity. 2 2 63 3054 61-3304 61-2269 59-6314 2 2 H 58-7707 36-1884 36-1715 1 2415 6450 0610 0485 + 25-22 19-84 i775 : -0876 + 30-59 Weig hted mean + 25-22 63 05 V a + Curvature "28 Radial velocity +25(6 1908. Dec. 5. G. M. T. 16 h 53'" P ORIONIS 2006. Observed by\ T s p, A<4K -,, TT Measured by j' ' I ' ASKEr1 ' Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. 2 63-3019 2 .58 '7614 2 61-3242 2 36'1852 3 61-2261 59-6262 2480 6480 0675 .0515 + 27-90 21 07 1 36-1782 1872 0967 +34-00 Weighted mean +27"14 V a + -63 Vd + '03 Curvature. . . - '28 Radial velocity. + 27'5 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 317 1908. Dec. 21. G. M. T. 15>> 24" ORION IS" 2054. Observed by) T p Measured by J J ' b - JfLA8K ' Wt, Mean of Settings. Corrected Star Setting. Disp' in rev" s Velocity. Wt. S 54 7148 54-0045 53-9654 .. ... 9630 0198 22'90 53-4020 4000 0218 25-05 I Mean of Settings. 53-0909 45 2924 45-2894 Corrected Star Settings. Disp' in rev ns . Velocity. 2907 0318 33 39 Weighted mean . . + 28'28 V a - 6-51 V d + -04 Curvature . '28 Radial velocity +21 '5 ORIONIS 2055. 1908. Dec. 21. Observed by T. H. PARKER. G. M. T. 15 h 29 Measured by J. S. PLASKETT. 2 2 H Mean of Settings. Corrected D - . Star ' p Setting*. mrev " 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp 1 in rev" s Velocity. 54-7334 53-9890 53-4172 2 1 2 53-1065 45-2957 45-2891 9690 i 0258 3990 -0208 + 29-84 23-90 2907 0318 +33-39 Weigt ited mean . -28-65 f 03 V a . V& - 6-51 Curvature Radial velocity . 28 +21-9 1908. Dec. 21. G. M. T. 16'' 54 )8 ORIONIS 2057. Observed by T. H. PARKER. Measured by J. S. PLASKETT. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev"' Velocity. Wt. Mean of Settings. Corrected Star Settings. C isp* in rev n * Velocity. 2 56 '6288 2 53-0900 2 54-7099 H 45-2802 2926 0327 + 34-34 2 53-9683 "9695 '0263 +30'42 2 45-2730 1 53-4072 4080 0298 34 24 Weighted mean +32'57 V fl . ..' - 6-53 V d . - -07 Curvature '28 Radial velocity +25'7 318 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 jS ORIOXIS 2058. 1908. Dec. 21. Observed by T. H. PARKER. G. M. T. 17 h 00 m Measured by J. S. PLASKETT. Wt. Mean of Settings. Coi'rected Star Settings. Disp 4 in rev" 3 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 3 Velocity. 2 2 it li 56-6155 54-6935 53-9424 53-3996 HH (Mr-ilM 53-0753 45'2t>86 45-2681 2853 0267 428-04 ! 9585 4140 0143 C358 + 16-54 41-14 Weight I ft ORTONIS 25. Ob Me re 7 , ... + 22-0 KETT. served by \ T o p asuredby J J - b - iLA * Wt. Mean of Settings. Corrected Star Settings. Disp 4 in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Dispt in rev" 8 i Velocity. < 2 2 ? 63-3046 61-3280 61-2436 59-6639 > 40"' /3 ORIONIS 2071. Observed by W. E. HARPER. Measured by J. S. PLASKETT. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. . Dispt in rev" 8 Velocity. 2 63 "3263 2 58-7844 2 61 '3499 2 36 2102 3 61-2612 2580 0775 + 32-04 1 36'2124 1964 1059 + 37-23 1 59-6928 6920 0935 38-25 Weighted mean +34'32 V a - 7-36 V d + -12 Curvature . . - " 28 Radial velocity +26'* 1908. Dec. 23. G. M. T. 1508 m j8 ORIONIS 2072. Observed by J. B. CANNON. Measured by J. S. PLASKETT. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Dispt in rev" 8 Velocity. 2 63 ' 3214 2 58-7812 2 61 '3398 2 36-2100 24 if 61-2460 59-6670 2500 6703 0695 0738 + 28-73 30-19 1 36-2152 1995 1090 + 38'32 Weighted mean +31'09 V a ... - 7-36 V d + '09 Curvature.. . - "28 Radial velocity +23'5 1908. Dec. 23. G. M. T. 15 h 20'" ORIONIS 2073. Observed by \ T o p Measured byJ J ' b> ^ LASKET Wt. Mean of Settings. Corrected Star Settings. Dispt in rev"" Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 ' Velocity. 2 63 '2965 2 58-7615 2 61 ' 3207 2 36-1910 3 U 61-2222 59-6362 2470 6595 0665 0630 + 27-49 25-77 1 36-1928 1954 1049 + 36-88 Weighted mean +28'73 V a - 7 36 Vd + -07 Curvature.... - '28 Radial velocity +21'2 r REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a p ORIONIS 2075. 321 1908. Dec. 26. G. M. T. 15" 50 m Observed by \ r ^ p rA ^KPTT Measured by /' b ' ^ LASI Wt. Mean of Settings. Corrected Star Settings. Disp' in rev ns Velocity. Wt. Mean of Settings. Corrected Star Settings. Dispt in rev ns Velocity. 2 2 3 63-3319 61-3525 61-2697 59-6900 2 2 H 58-7877 36-1851 36-1791 .::::;':' ::: 2622 6850 0817 0885 +33 77 36-21 1882 0977 + 34-45 Weig hted mean ..... h34 52 f- -01 V a - 8 68 Curvati re 28 Radial velocity +25'6 ft ORIONIS 2076. 1908. Dec. 26. Observed by \ T e Vr G. M. T. 16" 00"> Measured by ) J " & ' PLA SKTT. Mean Wt. of 1 Settings. Corrected Star Settings. Disp' in rev ne Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp 4 in rev" 8 Velocity. 2 63-3051 2 61-3204 :. 61-2357 1J 59-6614 2 2 li 58 7573 36-1624 36-1630 2590 6874 0785 0919 + 32-45 37 60 1950 1045 + 36 74 Weig hted mean h 34-81 V a .... - 8-68 01 - "28 V d Curvatu Radial veloi re :itv.., . +25-9 1908. Dec. 26. :. M. T. 16'- 09" ORIONIS 2077. 3r^4}j-s.r"s Mean Corrected of Star Settings. Settings. 63-3424 61-2012 59-6842 *2450 6730 Disp 4 in rev ns Velocity. 0645 +26-66 0765 31-30 25a Wt. Mean of Settings. 58-7943 36-1993 36-2132 Corrected Star Settings . 2082 Dispt in rev 1 " 1177 Velocity. + 41-38 Weighted mean + 31 ' 48 V a - 8 68 Vrf - -02 Curvature ... - '28 Radial velocity +22'5 322 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 1908. Dec. 26. G. M. T. 16 1 ' 18'" /3 ORIONIS 2078. Observed by) T -r> r . Measured by }J. S. PLASKKTT. Wt. Mean of Settings. Corrected Star Settings . Disp 1 in rev ns Velocity. Wt. Mean of Settings. Corrected Star Settings . Disp* in rev na Velocity. 2 63'3147 2 58 ' 7684 2 61-3334 2 36-1610 2 61-2290 2410 0605 + 25-01 1 36-1507 1900 0995 + 34-98 1 69-6970 7120 1135 46-45 Weighted mean +30 92 V a - 8'68 V d -04 Curvature ... - ' 28 Radial velocity +22'0 /3 ORIONIS 2079. 1908. Dec. 27. Observed by \ T p G. M. T. 14'> 07"' Measured by } J - b " l LASKKI Wt. Mean of Settings. Corrected Star Settings . Disp 4 in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings . Disp* in rev'" Velocity. 2 2 3 2 63-3248 61-3453 61-2754 59-7087 2 2 1 58-7809 36-1593 36-1787 2750 7115 0945 1150 + 39-07 47-05 2140 .1235 4:; 42 Weighted mean 42 45 15 V - 9'08 Vd Curvature 28 Radial velocity +33'2 1908. Dec. 27. G. M. T. 15 h 10 ra ORIONIS 2080. Observed by\ T p Measured by }J- S. PLASM.TI. Wt. Mean of Settings. Corrected Star Settings . Dispt in rev Velocity. Wt. Mean of Settings. Corrected Star Settings . Disp' in rev" s Velocity 2 63'3504 2 58 ' 8064 2 61-3730 2 36'18?3 3 1 61-3054 59-7017 2780 6790 0975 0825 + 40-31 33'75 4 36-1975 2095 1190 4 41-84 Weighted mean +39'02 V a - 9-08 Vd ""> Curvature. . - '28 Radial velocity + 29'7 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 323 1908. Dec. 31. G. M. T. 15 h 19'" ft ORIONIS 2082. Observed by W. E. HARPER. Measured by J. S. PLASKETT. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev"' Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp 1 in rev 08 Velocity. 2 54 "7142 2 53-0938 >i 54'OllS 2 45 2860 2855 0368 + 38 53 2 53 '9684 '9790 0224 +25 '84 2 45-2716 2 53-4146 4225 0323 37-03 Weighted mean , + 33'80 V a - 10-77 Va- : 'GO Curvature... - '28 1908. Dec. 31. G. M. T. 15>> 23 Radial velocity + 22'7 jS ORIONIS 2083. Observed by W. E. HARPER. Measured by J. S. PLASKETT. Mean Wt. of 1 Settings. Corrected Star Settings. Disp' in rev 1 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in re\ ns Velocity. 2 54 ' 7063 2 53'0866 2 54-0015 'H 45-2868 2850 0363 + 38-00 2 ! 53-9690 '9860 0294 + 33'92 ? 45-2719 1 53 4065 4215 0313 35-88 Weighted mean + 35'72 V a - 10-77 Vd -00 Curvature .... '28 Radial velocity . + 24'7 1908. Dec. 31. G. M. T. 15" 29"' ft ORIONIS 2084. Observed by W. E. HARPER. Measured by J. S. PLASKETT. Wt. Mean of Setting. Corrected Star Settings. Disp* in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. 2 54 ' 6938 2 53-0745 -> 53-9878 2 45'2702 28i2 0325 + 34 02 2 53 9587 *'9880 0314 + 36'23 2 45-2600 1 53-3888 4160 0258 29 57 Weighted mean + 34'01 V a - 10-77 Va 'GO Curvature - '28 Radial velocity + 23'0 324 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 P ORIONIS 2085. 1908. Dec. 31. Observed by W. E. HARPKK. G. M. T. IS* 57 m Measured by J. S. PLASKETT. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev 118 Velocity. Wt. Mean of Settings. Corrected Star ' Settings. Disp' in rev lls Velocity. 2 2 3 li 54-6997 53-9927 53-9592 53-4022 2 2 2 53-0777 45-2854 45-2717 2895 0408 + 42-71 9835 4255 0269 0353 ' + 31-03 40-46 Weighted Rac p ORIONIS 209 1909. Jan. 6. G. M. T. 16 h 49'" mean + 37-57 V a .. - 10-77 oo - '28 Vd... Curvature, ial velocity . . 4- 26-5 ARPER. SKKTT. 2. Observed by W. E. H Measured by J. S. PL-? Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. Wt. Mi an of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. 2 54'7150 2 53 '0905 2 54-0102 U 45-2713 '2730 '0243 + 25-44 3 63-9756 9860 0294 + 33-92 2 45 '2734 li 53-1128 4230 0328 37-60 Weighted mean +32'72 V a .: -1321 Vd - '16 Curvature . - ' 28 Radial velocity +19'1 1909. Jan. 6. G. M. T. 16 h 53 P ORIONIS 2093. Observed by W. E. HARPER. Measured by J. S. PLASKETT. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 9 Velocity. Wt. Mean of Settings. Corrected Star Settings- Uisp' in rev"" Velocity. 2 54-7120 2 53-0884 2 54-0046 2 45 2787 '2750 '0263 + 27-48 3 53-9727 9800 '0294 + 33'92 2 45 '2773 H 53-4136 4250 0348 39-89 Weighted mean +33'30 V a -13-21 Va- - 16 Curvature. . - "28 Radial velocitv... . +19 '6 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a /3 ORION IS 2034. 325 1909. Jan. 6. Observed by W. E. HARPEK. G. M. T. 17 h 13 Measured by J. S. PLASKETT. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. 2 2 3 2 54 7235 54-0160 53-9S67 53-4193 2 2 2 53-1074 45-2957 45-2876 2830 0343 +35-81 9850 4143 0284 0241 + 32-77 27-63 Weight I p ORTONIS 20< 1909. Jan. 6. G. M. T. 17 h 16"' ed mean ... - f 32-17 + 18-5 ABFER. VSKETT. v a .. -13-21 16 - -28 Vd Curvatu Radial velocit, 15. < re f Observed by W. E. H Measured by J. S. PL. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 9 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev ns Velocity. 2 2 2 1 56-6440 54-7198 53-9780 53-4356 2 2 2 53-0990 45-2880 45-2821 2815 0328 + 34 34 9830 4380 0264 0478 + 30-46 54-79 Weight ed mean h 34-89 V a . -13 21 16 - '28 Vrf. Curvature Radial velocity |8 ORIONIS 2105. 1909. Jan. 7. C G. M. T. 12 h 49 m ] + 21 2 LASKETT. >bserved by \ T q T> Measured by / J - b ' * Wt. Mean of Settings. Corrected Star Settings. Uisp* in rev"' Velocity. Wt. Mean of Settings.. Corrected Star Settings. Disp in rev ns Velocity. 2 54 7033 2 53-0832 2 53-9964 1 45-2868 3 li 53-9532 53 4150 9600 4215 0168 0433 + 19-43 49-76 2 45-2834 2902 0313 +32-87 Weighted mean +30'57 V a -13-59 V b ' ^ LASKETT - Wt. Mean of Settings. Corrected Star Settings. Disp* in rev 118 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. 2 54-7190 2 53'0925 1 54-0072 2 45 '2938 2i H 53-9772 53 4133 9715 4097 0283 0315 + 32 73 36-20 2 45-2933 2931 0342 +35.91 Weighted mean +34'66 V a -13-59 Vd - -11 Curvature. . . - ' 28 Radial velocity +20'7 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 327 190!). Jan. 7. G. M. T. 16 h 27 m ORIONIS 2111. Observed by\ Measured by/ p T . KWTT ^ LA8KETT - Wt. Mean of Settings . Corrected Star Settings . Disp* in rev 11 " Velocity. Wt. Mean of Settings. Corrected Star Settings . Diap' in rev" 8 Velocity. 2 63 3019 2 58'7700 2 61 3278 H 36-2038 2023 0693 + 24-46 2 61 2471 2315 0829 +34-37 2 36-2253 1 59-6883 6760 1068 43-81 Weighted mean + 33 16 V a - 13-59 V d - '11 Curvature - '28 1909. Jan. 7. G. M. T. 16 h 37 m ORIONIS 2112. Radial velocity +19'2 Observed by \ j s PTASKETT Measured by / ' Wt. Mean of Settings. Corrected Star Settings . Dispt in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev ns Velocity. 2 63-2779 2 58 '7484 2 61*3033 36-2003 2120 0790 + 27-86 3 61'2146 2236 0750 + 31 '51 2 36-2131 o 59-6353 6455 0763 31 30 Weighted mean + 30'60 V a - 13*59 \d - *11 Curvature - '28 Radial velocity + 16 6 1909. Jan. 7. G. M. T. 16'- 56 ORIONIS 2114. Observed by) T Measured by f' L \Vt. Mean of .Settings. Corrected Star Settings . Dispt in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Diap' in rev 1 " Velocity. 2 63-2829 1 58-7582 > (il'3072 li 36-1955 2045 .0715 + 25-22 8 61 ' 2181 *'2220 0734 + 30'43 2 36'2146 li 59 G679 6695 1003 41-14 Weighted mean V a .......... V d Curvature... + 31 '80 - 13-59 - 'It - "28 Radial velocity +17'8 328 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 8 ORIONIS 2117. 1909. Jan. 8. Observed by T. H. PARKER. G. M. T. 15 h 48 m Measured by J. S. PLASKETT. Wt. Mean of Settings. Corrected Star Settings . Disp' in rev"' Velocity. Wt. Mean of Settings. Corrected Star Settings . Disp' in rev 118 Velocity. 2 1 2 1 54-6880 53-9760 53-9517 53-3882 2 2 2 53-0662 45-2638 45-2622 2850 0261 + 27-41 9750 4113 0318 0331 + 36-78 38-04 Weighted mean + 33-28 - 13'% 09 28 V, Curvatu Radial veloc ft ORIONIS 2118. 1909. Jan. 8. G. M. T. 15 h 52 m IV re ity. . . + 18-9 KER. KETT. bserved by T. H. PAR [easured by J. S. PLAS Wt. Mean of Settings. Corrected Star Settings. Disp' in rev na Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. 2 2 2 1 54-7077 53-9948 53-9690 53-4030 2 2 2 53-0872 45-2898 45-2837 2935 0346 + 36 33 9730 4060 0298 0278 + 34-47 31-84 Weigl ited mean + 34-69 V a - 13-96 - -09 - -28 Curvature Radial velocity , . + 20-3 1909. Jan. 12. G. M. T. ll h 55 m /3 ORIONIS 2122. Observed by \ T c p .,,.. Measured by) J ' b> ^ LASKKI l - Wt. Mean of Settings. Corrected Star Settings. Dispt in rev 118 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev 1 " Velocity. 2 54 7074 2 63-0858 2 53 9968 2 45 '2886 5* 53-9694 53-4238 9735 4275 0303 0493 +33-80 54-97 2 45-2856 2905 0316 + 34-92 Weighted mean + 41 '91 V a ... - 15-39 Vd + -23 Curvature - '28 Radial velocity + 26'5 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 329 1900. Jan. 12. G. M. T. 11" 59'" j3 ORIONIS 2123. Observed by \ T p A , KPTT Measured by {' ' ^ LASKETT - Wt. Mean of Settings. Corrected Star Settings. Disp< in rev" 9 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. 2 54 ' 7088 2 53-0880 2 53 9990 2 45-2791 2 53-9836 53-4085 9836 4105 0428 0323 + 47'75 36-01 1 45-2727 2890 0301 + 33-26 Weighted mean + 41 42 V a - 15-39 V d + -23 Curvature... - '28 Radial velocity + 26'0 11)09. Jan. 12. G. M. T. 12 h 09' j8 ORIONIS 2124. Observed byl T Measuredby/ J - Mean Corrected Mean Corrected of Star . "P,,, Velocity. Wt. of Star Disp Velocity. Settings. Settings. Settings. Settings. 54-7008 2 53-0750 53-9928 2 45-2813 53-9598 9700 0268 + 29-90 2 45-2783 2905 0316 + 34 92 53-4100 4225 0443 49-39 Weighted mean + 35 ' 97 Va - 15-39 Vd + '23 Curvature - '28 1909. Jan. 12. G. M. T. 12'' 12 ra Radial velocity . . + 20'5 p ORIONIS 2125. Observed by 1 T p .OKITTT Measured by/ 1 '' b ' ^ LASKETT ; Wt. Mean of Settings. Corrected Star Settings. Disp' in rev 118 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev n> Velocity. 2 54-7110 2 53-0858 2 54-0045 2 45-2870 I 53-9770 53-4077 9775 * -4105 0343 0323 + 38-27 36-01 2 45-2840 2905 0316 + 34-92 Weighted mean +36'77 V a -15-39 Vrf + '23 Curvature. ...'... - '28 Radial velocity +21 '3 330 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 ORIONIS 2120. 1909. Jan. 12. G. M. T. 12 h 15" Observed by 1 y PLASKETT Measured by/'*' ft ' ^ LASKETT - wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. ' Dispt in rev ns Velocity. 2 54'7047 2 53-0813 2 54-0000 2 45-2910 2.1 ll 53-9770 53-4113 9830 4180 0398 0398 + 44-40 44 37 1 45-2885 2910 0321 + 35-47 Weighted mean + 42'60 V a -15'39 Va- + '23 Curvature - '28 Radial velocity +27;2 1909. Jan. 12 G. M. T. 12 h 18"' ORIONIS 2127. Observed by ) T o Measured by/ >J< b " Wt. Mean of Settings. Corrected Star Settings. Dispt in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Dispt in rev" 8 Velocity. 2 54-7144 2 53-C960 2 64-0082 2 45'2991 I- 1 Ul *-w 53-9767 53-4291 9765 4224 0333 0442 +37-15 49-28 2 45-3000 2945 0356 + 39-34 Weighted mean +40'91 V a -15-39 Vd + '23 Curvature. .. - '28 Radial velocity + 25 ' 5 1909. Jan. 13. G. M. T. 15 h 36 m j8 ORIONIS 2128. Observed by J. B. CANNON. Measured by J. S. PLASKETT. Wt. Mean of Settings. Corrected Star Settings. Dispt in rev ns Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. 2 54-7086 2 53' 09*20 2 54-0031 2 45 ' 2968 2 2 53,9775 53-1281 9790 4275 0358 0493 + 41-41 56-65 2 45-3012 2980 0391 4 41'06 Weighted mean +46"i V a -15-81 Vd - -09 Curvature . . - '28 Radial velocity +30'2 REPORT OF THE CHIEF ASTRONOMER 331 SESSIONAL PAPER No. 25a j8 ORIONIS 2129. 1909. Jan. 13. Observed by W. E. HARPER. G. M. T. 15 h 41'" Measured by J. S. PLASKETT. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. 2 54 7082 2 53-0893 2 54 -0002 2 45-2978 2i 1* 53-9730 53-4061 9748 4068 0316 0286 + 36-54 32-86 1* 45-2852 2810 0221 + 23-20 Weighted mean +31'90 V a -15-81 Vd -09 Curvature . . - "28 Radial velocity +15'7 1909. Jan. 13. G. M. T. 15 h 46" /3 ORIONIS 2130. Observed by W. E. HARPER. Measured by J. S. PLASKETT. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. 2 54 '6985 9 53-9934 2 1 53-9782 53 4029 9880 4115 0448 0333 +51-82 38-26 Wt. Mean of Settings. Corrected Star Settings. Disp* in rev n " Velocity. 2 53-0813 2 45-2892 2 45-2940 2984 0395 + 41-48 Weighted mean +44 97 V a -15-81 V d - -09 Curvature "28 Radial velocity +28'8 1909. Jan. 15. G. M. T. 15 1 ' 11'" ORIONIS 2142. Observed by J. B. CANNON. Measured bv J. S. PLASKETT. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. 54-7058 2 53-0911 2 53-9996 2 45-2970 I 53'<752 53-4083 * -9790 4105 0358 0323 + 4i-40 37-14 2 i 45-3055 3021 0432 + 45-36 Weighted mean + 41 ' 28 V a -16-50 Vd - -04 Curvature - '28 Radial velocity.. 24-5 332 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 j8 ORIONIS 2141. 1909. Jan. 15. Observed by J. B. CANNON. G. M. T. 14 h 54 m Measured by J. S. PLASKETT. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in Rev" 8 Velocity. 2 2 2 1 56-6150 54-7025 53-9628 53-3821 2 2 3 53-0735 45-2772 45-2777 9778 3975 0346 0193 + 40-02 22-18 2940 0351 + 36-86 Weighted mea V^.. n f 35-47 -16-50 Vrf . . -04 Curva . Radial ve /3 ORIONIS 2113. 1909. Jan. 15. G. M. T. 15" 15 m ture . - '28 locity 1-18-6 CANNON. PLASKETT. ! Observed by J. B. Measured by J. S. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. I- 1 WtO tO WH 54-7162 54-0069 53 9895 53-4092 to to to 53-0946 45-2937 45-3062 9844 4040 0412 0258 + 47-65 29-65 3061 0472 + 49-56 Weighted mea V, .... n + 44-08 - 16 50 04 - '28 Vrf .. Curvature Radial ve ft ORIONIS 2144. 1909. Jan. 15. O G. M. T. 15 h 19 m M ocity + 27-2 TON. KETT. oserved by J. B. CANI "easured by J. S. PLAS Wt. Mean of Settings. Corrected Star Settings . Disp* in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings . Disp 1 in rev" 8 Velocity. 2 54-7053 2 53-0782 2 53-9945 2 45-2864 1 53-9672 9750 0318 + 36-78 2 45-2847 2920 0331 + 34-76 1 53-4103 4200 0118 48-03 Weighted mean .. + 38'i V a - 16-50 Vd - -04 Curvature. ... - '28 Radial velocity + 21 ' 8 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 1909. Jan. 16. G. M. T. 12 h 25" ORIONIS 2151. Observed by I T Q, Measured by T- b ' 333 Wt. * Mean . f Settings. Corrected Star Settings . Disp< in rev"- Velocity. Wt. Mean of Settings. Corrected Star Settings . Disp' in rev 1 " Velocity. 2 54 '0926 2 53-0657 2 53-9756 2 45-2780 1 2 53'9598 53-3854 9850 4104 0418 0322 -t-48'25 36 00 3 45-2970 3130 0541 + 56-61 Weighted mean + 48'35 V a - 16-82 V d + -13 Curvature ... - "28 Radial velocity. + 31-4 l!Ht!l. Jan. 16. G. M. T. 12 h 36'" ORIONIS 2152. Observed by) T Measured by / J - Wt. Mean of 54 6990 53 9982 53-97:38 53-4168 Corrected Star Settings . Disp' in rev" 8 Velocity. 9820 4210 0388 0428 + 44-78 48-18 Wt. Mean of Settings. 53 0859 45-2919 45-2978 Corrected Star Settings . 2995 Disp* 0406 Velocity. + 42-63 Weighted mean +44'60 V -16-82 V/ + -13 Cur vature. ... - '28 1909. Jan. 10. G. M. T. 12 h 44'" Radial velocity +276 ORIONIS 2153. .Vt. Mean of Settings. Corrected Star Settings . Disp 1 in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings . Disp* in rev" 8 Velocity. ) 51-7003 2 53-0787 54-0022 9 45-2970 2 1 1 53-9786 53--J072 3886 4160 0454 0378 + 52-51 43-44 o 45 3131 3100 0511 +53-66 Weighted mean + 51 ' 38 V a - 16-82 Vd + -13 Curvature - "28 Radial velocity. . + 34-4 334 9-10 EDWARD VII., A. 19K /3 ORIONIS 2154. 1909. Jan. 16. Observed byjj g p IASKKTT G. M. T. 12 h 52'" Measured by / d ' Wt. Mean of Settings. Corrected Star Settings. Dispt in rev" 9 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity 2 2 2 1* 56-15114 54-6911 53-9844 53-4059 2 2 2 53-0724 45-2845 45-3008 0025 4220 0593 0438 + 68-59 49-23 3100 0511 +53-; Weightec Ra |8 ORIONIS 21 1909. Jan. 16. G. M. T. 12 h 59 m mean + 57-88 13 f 40'<) JKETT. V a -16-82 + Curvature dial velocity - '28 55. Observed by \ T a T> T . , AT j i f d t5. JT LA5 Measured byj Wt. Mean of Settings. Corrected Star Settings. Disp* in rev ns Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp 1 in rev" 8 Velocit] 2 2 2 2 56-6278 54-7078 54-0014 53-9853 2 2 2 2 53-4202 53-0880 45-2940 45 313G 4220 0438 49-2 9875 0443 +51-03 3130 0541 + 53-6 Weightec Ra /3 ORIONIS 21 1909. Jan. 16. G. M. T. 13 h 12'" mean + 51-01 ; 13 f 33-0 iKETT. V a -IG'82 Vd r . + Curvature dial velocity . - '28 56. Obseived by\ T a p Measured by J J> " rLAk Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocit; 2 54-7101 2 53-0934 2 54-0028 2 45-3008 4 2 i 53-9856 53-4297 9845 4250 0413 0468 +47-77 53-78 3 45-3214 3140 0551 + 58-C Weighted mean + 52'82 V a -16-82 Vd + '13 Curvature '28 Radial velocity + 35'8 REPORT OF THE CHIEF ASTRONOMER iESSlONAL PAPER No. 25a 335 1!K)9. Jan. 17. G. M. T. 13 1 ' 48" /3 ORION IS Mlf>7. Observed by 1 T a Measured by >' & Wt Mean of Settings. 54-6992 53-9936 53-9741 53-3965 Corrected Star Settings. Disp' in rev" 9 Velocity, Wt. Mean of Settings. 2 53 0802 2 45-2896 UVi'i 0418 0273 + 48-34 31 37 2 45-3062 Corrected Star Settings. 3102 ! Velocity. 0513 +53-87 Weighted mean , V a Vd Curvature . + 47 -17-11 - -28 Radial velocity + 29' 1909. Jan. 17. G. M. T. 13'- 56" J3 ORIONIS 2158. Observed by ) T Measured by / J ' \Vt. Mean of Settings. Corrected Star Settings. Disp 1 in rev 118 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp in rev 119 V elocity. 2 54'6898 2 53'0742 7 53-9898 2 - 45 '2874 2 53-9655 9835 0403 + 46-61 2 45 2947 3010 0421 + 44-21 2 53-3969 4130 0348 39 99 Weighted mean +43'60 V a -17-17 Vd + '05 Curvature '28 Radial velocity +26'2 1909. Jan. 18. G. M. T. 12* 41" ft ORIONIS 2161. Observed by 1 T c p ,,, Measured by / J> b> FLASKKTT - Wt. Mean of Settings. Corrected Star Settings. Dispt in rev" 9 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev ns Velocity. 2 2 2 H 2 54-7073 53 9976 53-9851 53-4217 2 2 24 53-0908 45-2916 45 3141 9880 4220 044S 0438 + 51-81 50-37 3160 0571 +59-96 Weight I 5a 24 ed mean , H -54-84 u '05 V a -17-17 Vd Curvatu Jadial velocity re 28 7 . ... (-37 1 336 9-10 EDWARD VII., A. 1910 1909. Jan. 18. G. M. T. 12 h 46 P ORIONIS 21<>2. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. 2 54-7174 2 53-0979 2 54'OUl 2 45 '3097 s 2 53-9987 53-4185 9900 4098 04(58 0316 + 54-12 36 34 2 45-3267 3105 0516 + 54-1^ Weighted mean +49'06 V tt -17 17 V d + '05 Curvature. . "28 1909. Jan. 18. G. M. T. 12 h 51 m Radial velocity +31'3 /3 ORIONIS 2163. I J. S. PLASKETT. Wt. Mean of Settings. Corrected Star Settings. Dispt in rev 118 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocil 2 54-7067 2 53-0858 2 53-9965 2 45-2994 3 1 53 9771 53-4107 9820 4147 0388 0365 + 44'87 41 94 2 45-3122 3001 0475 + 49M Weighted mean . -17 51 Curvature . - '28 + 46 05 + -08 Radial velocity . . + 28 ' 3 1909. Jan. 18. G. M. T. 13 h 06"' /S ORIONIS 2164. Observed by) T PrA5 , KRTT Measured by / J< h - ^ LASKETT - Wt- Mean of Settings. Corrected Star Settings. Dispt in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev"" Velocity. 2 54-7077 2 53-0867 2 63-9990 2 45-2983 :::::::.. 2 2 53-9926 53-4235 9954 4261 0521 0479 +59-16 54-04 3 45-3107 3060 0471 + 49 46 Weighted mean +53'J V a -17-57 Va + '08 Curvature "28 Radial velocity +35'8 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 337 1909. Jan. 18. G. M. T. 13 h 10 m ORIONIS 2105. Observed by\ T q p rAt , K1 , TT Measured by) J ' b ' FLASKETT " Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev 118 Velocity. 2 54 '7128 2 53-0967 2 54 0073 2 45-3114 3 1 53-9885 53-4284 9830 4215 0398 0433 + 45-93 48-66 2 45-3277 3100 0571 +5366 Weighted mean Vd Curvature -17-57 +48'96 + -08 "28 Radial velocity +31'2 ft ORIONIS 2166. 1909. Jan. 18. Observed byl T s p TA< , KltTT G. M. T. 13 h 14 Measured by/ J ' b ' ^ Wt. Mean of Settings. Corrected Star Settings. Disp' in rev"* Velocity. Wt. Mean of Settings. Corrected Star Settings. Dispt in rev" 8 Velocity. 2 2 U l| 54-7106 53-9998 53-9796 53 4221 2 2 3 53-08% 45-3060 45-3184 9805 4225 0373 0443 + 43 14 50-95 3065 0471 + 49-46 Weigh Rs ted mean h 48-25 h 'OS 1-30-5 V a . 17 57 Vd Curvature 28 idial velocity . . . ft ORIONIS 2177. 1909. Jan. 26. Observed byl T , p TAt , KFTT G. M. T. 10" 36"' Measured by/ J ' b ' ^ LASK Wt. n 2 2 1 Mean of Settings. Corrected Star Settings. Disp' in rev" s Velocity. Wt. Mean of Settings. Corrected Star Settings. Dis^ in rev 1 ' 8 Velocity. 5T7218 54-0098 53 9936 53-4276 2 2 2 53-0968 45-2904 45-2922 9856 4200 0424 0418 + -19-04 48-03 21)5-1 0365 + 38-33 Weigh RJ 25a 24J ted mean f 44-55 (- -22 V a ... 19-95 V d Curvature 28 idial velocity f24'6 338 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 1909. Jan. 26. G. M. T. 10 h 51 m ORIONIS 2178. Observed by} T Measured byj J> S> Wt. Mean of Settings Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Dispt in rev 118 Velocity. 2 54 '7537 2 53-1294 2 54-0433 2 45-3207 3 U 54-0181 52-4554 9766 4150 0334 0368 +38-63 42-29 1 45-3132 28C1 0272 + 2S-56 Weighted mean -t-37'80 V a -19-95 Vd + '22 Curvature - '28 Radial velocity + 17'8 /3 ORIONIS 2179. 1909. Jan. 26. Observed by \ T & " rLASK Wt. Mean of Settings. Corrected Star Settings. Dispt in rev 118 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev 118 Velocity. 2 2 3 i o4 7394 54-0262 54-0003 53-4399 2 2 2 53-1107 45-2972 45-3035 9760 4175 0328 0393 + 37-93 45 14 3000 0411 + 43-16 Weighted mean f 40-49 f -22 v a ... -19-95 Vd.. Curvati Radial velocity re - '28 t-20'5 340 1909. Jan. 28. G. M. T. ll h 21 m DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 j8 ORIONIS 2184. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" s Velocity. Wt. Mean of Settings. Corrected Star Settings. Dispt in rev" 8 Velocity. 2 54-7322 2 53-1120 2 54-0224 2 45-3111 3 54-0007 9800 0368 +42-56 2 45-3122 2947 0358 + 37 59 1 53-4160 3940 0158 18-16 Weighted mean '. . .. +36'84 V a -20-51 Va- + -21 Curvature. . . " 28 1909. Jan. 28. G. M. T. ll h 25'" Radial velocity +16'3 /3 ORIONIS 2185. SftSfl "&}'"*" " Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. S- Velocity. 2 54-7073 2 53-0869 2 53 9993 2 45-2864 2 53-9800 9830 0398 + 46-03 2 45-2882 2954 0365 + 38-33 1 53-4194 4220 0438 50-33 Weighted mean + 43 81 V a -20-51 Va- + -21 Curvature - "29 1909. Jan. 28. G. M. T. 11" 29'" Radial velocity. ft ORIONIS 2186. + 23' Observed by \ f R p, At(KPTT Measured byj J ' h ' ri ' ASK Wt. Mean of Settings. Corrected Star Settings. Dispt in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp 1 in rev" " Velocity. 2 54-7073 2 53-0851 2 54-0002 2 45-2893 2 1 53-9697 53-4020 9735 4060 0303 0278 + 35/04 31-94 2 45'2888 2930 0341 + 35-81 Weighted mean + 34 ' 73 V a -20-51 Va- + -21 Curvature - 28 Radial velocity 14-2 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 341 1909. Jan. 28. G. M. T. ll h 41"' ORIONIS 2187. Observed by \ T Measured by/ J ' Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" s Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev 118 Velocity. 2 54 7131 2 53-0944 2 54-0015 2 45-2911 2 li 53-9731 53-4183 9705 4140 0273 0358 + 31-57 41-14 2 45-2883 2908 0318 +33-39 Weighted mean +34'84 V a -20-51 Vd + -21 Curvature . . - '28 1909. Jan. 28. G. M. T. 11" 44"' Radial velocity -. '+ 14 ' 3 ft ORIONIS 2188. Observed by\ -, o Measured by J ' ' ' Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 9 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. 2 54'7128 2 53 0905 ?, 54 0033 2 45-2924 2 53'9fi5i8 53-4200 9614 4187 0182 0405 + 21-05 46-54 14 45-2857 2869 0280 + 29-40 Weighted mean +31'20 V a , -2051 Vd + 21 Curvature... - '28 Radial velocity. ... +10'6 1909. Jan. 28. G. M. T. II 1 ' 47' ft ORIONIS 2189. Observed by) T s p rAtsKFTT Measured by/ J ' b - ^ LASKETT - Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. (NIMIM rH* 54-7175 54-0085 53-9802 53-4243 2 2 14 53-1003 45-2987 45-2937 9730 '4150 0298 0368 + 34-46 42-29 2886 0397 + 41-69 Weights Rad d mean t-38'98 f 21 V a - 20-51 Curvatui ial velocity e. . 28 t-18-4 342 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 ORIONIS 2195. 1909. Jan. 29. G. M. T. 12 1 ' 53" Ooserved by J. B. CANNON. Measured by J. S. PLASKETT. Wt. Mean of Settings. Corrected Star Settings. Disp in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. 2 54-7212 2 53-1014 2 54-0170 2 45-2906 2 1 53 '9840 53-4261 9710 4135 0278 0353 + 32-15 40-56 i 45 '2928 2958 03G9 l 38 75 Rad /3 ORIONIS 21< 1909. Jan. 29. G. M. T. 12'' 57 m . V a -20'79 Va- + '05 Curvatur ial velocity e -28 + 14-9 ML Observed by J. B. CANNON. Measured by J. S. PLASKETT. : Wt. Mean of Settings. Corrected Star Settings. Disp 4 in rev" s Velocity. Wt. Mean of Settings. Corrected n - t Star ; ' S P , Velocity. Settings. m rev 2 2 3 54-7168 54-0073 53-9817 53-4324 2 2 53-0946 45-2894 45-2877 J 9762 4270 0330 0488 + 38 16 56-08 2919 0330 +34-65; Weighte d mean ' +38'90 V a -20-79 Vrf.. + -05 Curvature "28 Rad |8 ORIONIS 218 1909. Jan. 2!). G. M. T. 13 h 01 ial velocity + 17-9 7. Observed by J. B. CANNON. Measured by J. S. PLASKKTT. Wt, Mean of Settings. Corrected Star Settings . Disp' in iev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Dispt in rev ns Velocity. 2 54-7222 2 53-0981 o 54-0097 2 45'2919 2 i 53-9881 53-4480 9790 4390 0358 0608 + 41-40 69-87 1 45-3034 3050 0461 + 48-41 Weighted mean + 47 ' 47 V a -20-79 Vrf + -05 Curvature...... - '28 Radial velocity. + 26-4 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 343 1909. Jan. 29. G. M. T. 13 05" ORIONIS 2198. Observed by J. B. CANNON. Measured by J. S. PLASKETT. Wt. Mean of Settings. Corrected Star Settings . Dis[>< in rev"" Velocity. Wt. Mean of Settings. Corrected Star Settings . Disp* in rev" 8 Velocity. > 54 7170 2 53'0924 2 54-0100 2 45-2871 2 14 53-9896 53'41(>4 9840 4120 0408 0338 + 47-18 38-84 2 45-2927 2992 0403 + 42-32 Weighted mean + 43 ' 1 4 V a - 20-79 Vd + '05 Curvature - "28 1909. Jan. 30. i J. M. T. 12'> 29" Radial velocity +22' 1 ORIONIS 2201. Wt. Mean of Settings. Corrected Star Settings . Disp' in rev !ls Velocity. Wt. Mean of Settings. Corrected Star Settings . Dihp' in rev" 8 Velocity. 2 54-7150 2 53-0957 2 54-0093 2 45*2906 3 1 53-9791 53 4193 9730 4130 0298 0348 + 34-46 39 99 2 45-2884 2914 0325 + 34-13 Weighted mean + 35 " 27 V a - 21-05 V d + -00 Curvature - "28 1909. Jan. 30. G. M. T. 12'- 41'" Radial velocity +14'0 ft ORIONIS 2202. Observed byl T s P IA , KFTT Measured by/ ' J ' b> ^ LASK Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. | Wt. Mean of Settings. Corrected Star Settings . Disp* in rev" 9 Velocity. 2 54-7150 2 53-5937 2 54-0022 2 45-2878 H 1" 53-9764 53-4141 9710 4100 0268 0318 + 30 99 36-54 2 45-2963 3020 0431 +45-26 Weighted mean + 38'57 V a - 21-05 V d + -06 Curvature . - "28 Radial velocity + 17 "3 344 1909. Jan. 30. G: M. T. 12 h 45 m DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 ORIONIS 2203. Wt. Mean of Settings. Corrected Star Settings. Dispt in rev 1 " Velocity. Wt. Mean of Settings. Corrected Star Settings. Dispt in rev 118 Velocity. 2 54-7115 2 53-0902 2 53-9970 2 45-2808 1 \ 53-9941 53-4224 9950 4240 - -0518 0458 +59-91 52 63 2 45 '2822 2950 0361 + 37-91 Weighted mean + 46 " 29 V tt -21-05 Vd + -06 Curvature - '28 Radial velocity +25'0 1909. Jan. 30. G. M. T. 12 h 48"' ft ORIONIS 2204. Observed by\ T Measured by/ J< Wt. Mean of Settings. Corrected Star Settings. Dispt in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Dispt in rev"" Velocity. 2 54-7152 2 53-0917 2 54-0046 2 45-2933 1 1 53-9739 53-4059 9712 4034 0280 0252 +32'38 28-96 2 45-29(59 2972 0383 + 40-22 Weighted Rac p ORIONIS 22( 1909. Jan. 30. G. M. T. 15 h 47 m mean 1-35-45 f '06 ' y a -21 05 Va Curvature lial velocity >5. Ol M< 28 M4-2 iKETT. (served by) T <, p 3asuredby/ J ' b - PLAS Wt. Mean of Settings. Corrected Star Settings. Dispt in rev 118 Velocity. Wt. Mean of Settings. Corrected Star Settings. Dispt in rev 118 Velocity. 2 2 3 li 63-3385 61-3585 61-2878 59-7215 2 2 14 58-7894 36-1737 36-1979 2744 7140 0939 1175 + 38 '82 48-07 2180 1275 + 44-83 Weightec mean t- 42-63 r -06 V a -21-05 Vd Curvature - -28 Radial velocity +21 '0 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 345 1009. Jan. 30. G. M. T. 16 1 ' 04" ORIONIS 2206. Wt. Mean of Settings. Corrected Star Settings. Disp 1 in rev" s Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 9 Velocity. 2 63 3436 2 58-7994 2 61-3644 2 36-1900 2 14 61 3040 59-7313 2850 '7150 1045 1185 + 43 20 48-48 1* 36-2046 2088 1173 + 41-24 Rac ORTONIS 22 1909, Jan. 30. G. M. T. 16 h 24 V a -'21-10 Vd Curvature lial velocity . . 24 - -28 4-M'fi 37. Observed by ) j g P L \SKFTT Measured by/ ' Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 . Velocity. Wt. Mean of Settings. Corrected Star Settings. tS. ~*. 2 2 3 14 63-3410 61 3604 61-3037 59-7308 2 2 2 58-7983 36-1943 36-2027 \ 2880 7160 1075 1195 + 44-44 48-89 2026 iizi +39 4i Weightec I mean. . 4-43-92 V a -21-10 24 - -28 Curvature Radial velocity +22'3 1909, Jan. 31. G. M. T. 17 h 16"> ORIONIS 2211. Observed by W. E. HARPER. Measured by J. S. PLASKETT. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 9 Velocity. 2 54 ' 7191 2 53-0951 2 54-0068 2 45-2834 2 1 53-9870 53 4342 '9800 4275 0368 0493 + 42-56 56 65 2 45-2806 2908 0319 + 33-50 Weighted mean + 41 ' 75 V -2133 Vd - 31 Curvature... - '28 Radial velocity + 19'i 346 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 ORIONIS 2212. 1!>0'J. Jan. 31. Observed by W. E. HARPER. G. M. T. 17 h 20 m Measured by J. S. PLASKETT. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. iS... Vdocit y- 2 2 2 1 54-7084 54-001l> 53-9833 53-4274 2 2 H 53-0894 45-2894 45-2886 ' 9835 4273 0403 0491 + 46-61 56-42 2928-; -0339 +3.VC.O Weight ed mean + 45 1 2 V a Vrf . -21-33 31 28 Curvatu Radial velocit; ORIONIS 2213. 1909. Jan. 31. ( G. M. T. 17 h 24 m re ? ... +23-2 )bserved by W. E. HARPER. Measured by J. S. PLASKETT. Wt. Mean of Settings. Corrected Star Settings. in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. *. ~ 2 2 2 1 54-7118 54-0115 53-9797 53-4258 2 2 2 53-0904 45-2938 45-2925 9737 4190 0305 0403 + 35-27 46-88 2923 0334 +35-U7 Weight I ^ORIONIS 22 1909. Jan. 31. G. M. T. 17 h 29'" ed mean , + 37 91 V -21-33 - -31 - -28 -,-10'fl Curvatu iadial velocity 14. ( ] re j Observed by W. E. HARPER. Vleasured by J. S. PLASKETT. Wt. Mean of Settings. Corrected Star Settings. Dispt in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. iS- Veiocit *- 2 2 i 4 54-7065 53-9988 53-9808 53-4149 2 2 2 53 0873 45 2835 45-2763 9840 4174 0408 0392 + 47-18 45-04 2864 0275 + 2X'X8 Weight ed iiHiaii +38'57 V a -21 33 31 - -28 Vd Curvature. . Radial velocity. +16 '6 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a ORION IS' 2215. 347 11109. Feb. 2. Observed by 1 T p , SI{] , lV ( i. M. T. II 1 ' 14 m Measured by / ''' Wt. Mean of Settings. Corrected Star Settings. Disp 1 in rev"" Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp 1 in rev" 8 Velocity. > 2 2 2 54T098 54 '0038 53-9791 53-4182 [ 2 2 2 53-0885 45-2951 45-3072 9803 4192 0371 0410 + 42-90 47-11 3067 0478 + 50'19 Weight ed mean j-46'73 1- '14 V a -2179 Vrf Curvatu Radial velocit J3 ORIONIS 2216. 1909. Feb. 2. Ol G. M. T. 11 23 M re - "28 ir . + 24-8 KETT. >served by\ T Pr 6 ?asuredbyr- b ' FL ' U Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocicy. 2 2 3 2 54-7162 54-0091 53-9864 53-4299 2 2 2 53-0940 45-3030 45-3047 9810 4250 0378 0468 + 43-72 53-78 2953 0364 + 38-22 Weigh tec Ra. /3 ORIONIS 22 1909. Feb. 2. G. M. T. ll h 26 mean h 45-02 f- '14 V a . . . . -21-79 Vd Curvature Jial velocity 28 h23'l K8TT. 17. Observed by \ T o PTAS Measured by J J - ^ ^ LAS Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Dispt in rev" s Velocity. 2 54-7143 2 53-0916 1 54-0053 2 45-2940 3 1 53-9820 53 4303 * -9790 4277 0358 0495 + 41-40 56-88 2 45-3032 3028 0439 + 46-10 Weighted mean +45'35 V -21-79 Vd + "14 Curvature ...." , - "28 Radial velocity. +23'6 348 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 j8 ORION IS 2218. 1909. Feb. 2. Observed by \ T , p ..___ G. M. T. 11" 29 m Measured by/' 1 ' b ' rLASI Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. 2 2 2 1 54-7101 54-0023 53-9848 53-4172 2 2 2 53-0910 45-2961 45-3020 9845 4160 0413 0378 + 47-76 43 44 2995 0406 + 42-63 Weighttc Ra ORIONIS 22 1909. Feb. 2. G. M. T. ll h 41 1 mean .- f 44-44 f -14 V a . .' -21-97 Curvature dial velocity - -28 f22'5 19. Observed by\ T p Measured by j J --*^ Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Dispt in rev ns Velocity. 2 54'7180 2 53 0937 2 54 0106 2 45-3002 3 l| 53-9813 53-4213 9740 4150 0308 0368 +35 62 42-29 2 45-3032 2966 0377 + 39-59 Weighted mean . .;.. +38'39 V Vd .. . . -21-79 + -14 Curvi Radial velo< /3 ORIONIS 2220. 1909, Feb. 2. G. M. T. Il h 45 m iture ... - '28 city. .... +16.5 Observed by Measured by JJ. S. PLASKETT. .Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 jVelocity. Wt. Mean of Settings. Corrected Star Settings. Disp 4 in rev lls Velocity. 2 54-7143 2 53-09^2 2 54-0073 2 4o'2903 3 1 53-9847 53-4305 9800 4250 0368 0468 +42-56 53-78 2 45-2967 3000 0411 + 43-16 Weighted mean +44'63 V a -21-79 Vd + '14 Curvature "28 Radial velocity +22'7 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 349 1909, Feb. 2. G. M. T. 11" 45" ORIONIS 2220* Observed by J. S. PLASKKTT. Measured by W. E. HARPER. Wt. .Mean of Settings. Corrected Star Settings. Disp' in rev lls Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev n " Velocity. 2 54 7580 3 53-1366 2 H 54-0249 53 '4623 9779 4151 0347 0369 + 40-03 42 40 2 3 45-3355 45-3285 3006 0417 + 43-78 Weighted mean . V a Vd Curvature. . -21 79 + 42-04 + '14 - '28 Check. Radial velocity +20'2 1909, Feb. 6. G. M. T. 12 h 29" ORIONIS 2236. Observed by 1 , Measured by/ J - Wt. Mean of Settings. Corrected Star Settings. Disp' in rev'" Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp k in rev ns Velocity. 2 54-7129 2 53-0895 2 54-0040 2 45-2921 2 1 53-9767 53-4149 9750 4143 0318 0361 + 36 78 41-48 3 45-2985 3000 0411 + 43 16 V a -22 07 24 28 Vd Curvature .... - Radial velocity +18-2 LASKETT. ORIONIS 2239. 1909, Feb. 6. Observed by \ T G. M. T. 12"50"> Measured by J J ' S. P Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp fc in rev ns Velocity. 2 54-7144 2 53 0925 2 54-0085 2 45-2967 2 4 53-9843 53-4083 .'9810 4052 0378 0270 + 43 72 31-03 2 45-3043 3012 0423 + 44 42 Weighted mean +42'62 V a -22-07 V d -24 Curvature... - "28 Radial velocity +20'0 350 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 ORIONIS 224(i. 1909. Feb. 6. G. M. T. 12 h 52" Observed by 1 T u u Measured by } J - S - lLASKETT - Wt. Mean of Settings. Corrected Star Settings. Disp' in rev 118 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" s Velocity. 9 54 7160 2 53-0936 2 54-0066 2 45-2951 2 2 53-9845 53-4254 9800 -4210 0368 0428 + 42-56 49-18 1 45-2950 2935 0346 + 36-33 Weighted mean + 43 ' 9fa V a -22-07 V d '24 Curvature '28 Radial velocity +21 1909. Feb. 6. G. M. T. 16 h 12" ORIONIS 2241. Observed by ) Measured by Wt. Mean of Settings. Corrected Star Settings. Disp 4 in rev 118 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp 4 in re V s ! Velocity. ] 2 63 '31 72 2 58-7726 2 61 '3357 2 36-1652 2 1J 61-2768 59-7176 ^858 7280 1053 1315 + 43-53 54-10 14 36-1710 2000 1095 + 38-00 j i Weighted mean +45-19 V a -22 73 30 28 Curvature Radial velocity. . + 21-9 iSKETT. |8 ORIONIS 2242. 1909. Feb. 6. Observed by \ T G. M. T. 16 h 43 m Measured by r'- 0< PL, Wt. Mean, of Settings. Corrected Star Settings. Dispt in rev ns Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp 4 in rev 118 Velocity. 2 63-3249 2 58 '7845 2 61 '3494 2 36 '1810 2 1| 61-2686 59-7224 2670 7220 0865 1255 + 35 76 51 34 ift 36-1972 2104 1199 + 42-16 Weighted mean +42'36 V a -22-73 Va - '30 Curvature "28 Radial velocity +19'1 REPORT OF TEE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a ft ORIOMS 2243. 351 1909. Feb. 7. Observed by\ T p IAa .., FTT G. M. T. 15 h Jl m Measured by/''' b ' r Wt. Mean of Settings. Corrected Star Settings. Disp in rev" 3 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev ns Velocity. 2 2 2 li 03-3350 61-3019 61-2972 59-7234 2 2 2 58-7918 36 1731 36-1874 2872 7150 1065 1185 + 44 03 48-48 2085 1180 + 41 '7V Weighted Radial ft ORIONIS 224 1909. Feb. 7. G. M. T. 15 h 25 m mean 4 44-42 V a -22 93 - -23 - 28 Vd Curvature - velocity + 21 '0 3KETT. 4. Observed byl . p Measured by J J - b ' ^ LAl Wt. Mean of Settings. Corrected Star Settings . Disp* in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings . Disp* in rev" 8 Velocity. 2 2 2 1 63-3380 61 "3554 61-2952 59-7458 2 2 1* 58-7900 36 1752 36-1830 2855 7388 1050 1423 + 43-41 58-21 2020 1115 + 39 20 Weightec Ra< ORIONIS 2& 1909. Feb. 7. G. M. T. 15 h 37 m mean + 45-30 v a .. - 22-93 23 28 Vd . . . Curvature lial velocity. +21-9 JKETT. 15. Observed byl T -p Measured by / J ' b " ^ LA ' Wt. Mean of Settings. Corrected Star Settings . Disp 1 in rev" 9 Velocity. Wt. Mean of Settings. Corrected Star Settings . Disp* in rev" 9 Velocity. 2 2 1* 63 3424 61-3620 61-2862 59-7488 2 2 1 58-7988 36-1867 36-1858 . -2692 7338 0887 1373 + 35-97 56-05 1963 1058 + 37-20 Weighted Ra( 25a 25 mean . . . . > + 41-45 V a - - 22-93 23 28 Vd Curvature lial velocity + 18-0 352 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 /3 ORIONIS 2249. 1909. Feb. 8. . Observed by T. H. PARKER. G. M. T. 13 h 32 m Measured by J . S. PLASKETT. Wt. Mean of Settings. Corrected Star Settings . Dispt in rev" 9 Velocity. Wt. Mean of Settings. Corrected Star Settings . Uispt in rev" 8 Velocity. 2 2 3 "2 54'7050 53-9998 53-9795 53-4276 2 2 2 53-0824 45-28(58 45-3024 9845 4375 04i3 0593 + 47-76 68-14 3092 0503 + 52-82 , Weighted Ra< P ORIONIS 225< 1909. Feb. 8. G. M. T. 13 h 36 m mean + 55-03 V a -23-11 08 - -28 Vd Curvature li;il velocity + 31-6 KEK. 8KETT. a. Observed by T. H. PAR Measured by J. S. PLA Wt. Mean of Settings. Corrected Star Settings . Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings . Disp* in rev" 9 Velocity 2 2 2 1 54-6972 5:5 '9910 53-9713 53-4184 2 2 H 53-0777 45-2869 45-2950 9835 4304 0103 0522 + 46-61 59-98 3027 0438 + 45-99 1 1 Weighted Ra ft ORIOMS 22. 1909. Feb. 8. G. M. T. 13'- 41'" mean + 49-37 V a - 23-11 08 28 Va Curvature iial velocity. 51. ( + 25 9 VRKEH. ASKETT. Observed by T. H. P. Measured by J. S. PL Wt. Mean of Settings. Corrected Star Settings. Disp' in rev 118 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp 1 in rv" s Velocity. 2 54-7049 2 53'0838 2 53-9982 2 45 '2878 2 3 53 9698 53-4168 9765 4225 U323 0443 + 37-35 50-91 !i 45-2914 2972 0383 + 40 22 Weighted mean + 44'27 V a - 23-11 V d - '08 Curvature . . - '28 Radial velocity +21' REPORT OF THE 'CHIEF ASTRONOMER 353 SESSIONAL PAPER No. 25a ORIONIS 2252. 1909. Feb. 8. Observed by T. H. PARKER. (T. M. T. 14 h Ol m Measured by J. S. PLASKETT. Wt. Mean Corrected of Star Settings. Settings. Disp' in rev 118 Velocity. Wt. Mean of Settings. Corrected Star Settings. Dispt in rev" 8 Velocity. . 2 > ? 54'7056 2 2 B 53-0882 45-2960 45-2982 53- 9980 53-9779 '9815 "0383 53-4076 4095 '0313 + 44-29 35-97 2958 0369 fS8'75 Weighted Rac ft ORIONIS 22; 1909. Feb. 8. (i. M. T. 14" 05 mean f-41'05 V -23 11 08 - -28 Va Curvatu ial velocity re 1-17-6 iRKER. iSKETT. >3. Observed by T. H. P; Measured by J. S. PL Wt. Mean Corrected of Star Settings. Settings. Disp' in rev 119 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 9 Velocity. 2 2 2 3 54-7217 2 2 2 53-1030 45-3090 45 3240 54 0110 1 53-9862 '9762 53-4354 '4230 0330 0448 + 38-16 51-48 3086 0497 +52-19 Weighted Rad p ORIONIS 22i 1909. Feb. 8. (i. M. T. 14 h 09 m mean 1-47-88 V a -23-11 - -08 - -28 V* Curvatu ial velocity re h24 1 IRKER. \8KETT. 4. Observed by T. H. P. Measured by J. S. PL Wt. Mean ; Corrected of Star Settings. Settings. Disp' in rev"" Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp e in rev"' Velocity. >> 2 2 1 54-7152 . 2 2 2 53-0993 45-3112 45 3142 54-0084 53-9930 *'9860 53-4357 4265 0428 +49-50 0483 55-50 2966 0377 +39-59 Weighted mean t- 46-74 V* -23-11 08 - -28 Vd.... Curvature . . . 25a 254 Radial velocity .. +23 - 3 354 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1915 /3 ORIONIS 2265. 1909. Feb. 10. Observed by W. E. HARPER. G, M. T. 12 h 07 Measured by J. S. PLASKETT. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. ' Disp* in rev" 9 Velocity. 2 2 2 1* 54-6937 53-9911 53-9691 53-4197 2 2 2 53-0767 45-2770 45-2980 9800 4310 0368 0528 + 42-56 6J-67 3146 0557 + 58-49 Weighted E Radis /3 ORIONIS 22f 1909. Feb. 10. G. M. T. 12 h 12 m ciean . f 53-29 f -05 V a - 23 ' 48 Va Curvature . . "98 il velocity . t-29'6 Kl'ER. SKETT. .6. Observed by W. E. H^ Measured by J. S. PLA Wt. Mean of Settings. Corrected Star Settings. Diap' in rev 118 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev ns Velocity. 2 2 2 2 54-7090 54-0052 53-9815 53 4312 2 2 2 53-0932 45-2916 45-2989 9780 4275 0348 0493 + 40 25 56-65 3009 0420 + 44-10 Weighted Ra ORIONIS 22( 1909. Feb. 10. G. M. T. 12 h 16 m mean M7-00 f- '05 V a -23-48 V + 45-68 Weighted nifan + 43'52 V a -23-05 Vd + -10 Curvature ... . - '28 Radial velocity +19'7 1909. Feb. 11. G. M. T. / ORIONIS 2270. Observed by ) Measured by J Wt. Mean of Settings. Corrected Star Settings. Disp' in rev"" Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" s Velocity. o 54-7082 2 53-0893 2 53-9963 2 45 '2824 2 1 53-9792 53-4083 9840 4095 0408 0313 + 47-19 35-97 a 45-2835 2947 0358 +37 59 Weighted mean . . '. + 41 ' 11 V a -23-65 V d + -10 Curvature . . "28 Radial velocity +17'3 1909. Feb. 11. G. M. T. ll h 49'" j8 ORIOXIS 2277. Observed by 1 T e Pl . SKirrT Measured by / J ' S ' L '- ASKETT - Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" s Veloci ty. 2 54-7699 2 53-0878 2 54-0019 2 45 '2944 2 53-9798 * -98i6 0378 + 43-72 u 45-3021 3013 0424 444-52 1 53 4279 4294 0512 58-83 Weighted mean + 47 ' 34 V a -23-65 Vd + -10 Curvatute - "28 Radial velocity ; +23'5 358 DEPARTMENT OF THE INTERIOR 1909. Feb. 13. G. M. T. 12 h 27" /3 ORIONIS 2278. 9-10 EDWARD VII., A. 1910 Observed by) T s p, AC , KFTT Measured by] J ' b ' ^ LA8KETT - Wt. Mean of Settings. Corrected Star Settings. Dispt in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star . Settings. Disp* in rev ns Velocity. 2 63-3466 2 58-8021 2 61-3632 2 36-1817 3 2 61-3156 59-7290 2975 7110 1175 1145 + 48-37 46-84 1 36-1930 2055 1150 + 40-31 Weighted mean + 46 ' 52 V a -24-00 Vd '00 Curvatui-e '28 Radial velocity +22'2 j8 ORIONIS 2279. 1909. Feb. 13. Observed by 1 T ^ p G. M. T. 12 h 40 Measured by/ J< o> e Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp 4 in rev 118 Velocity. 2 2 3 2 63-3312 61-3531 61-3032 59-7212 i- 1 to ta tot- 58-7858 36-1657 36-1698 2970 '7180 ilG5 1215 + 48 16 49-71 1983 1078 + 37'78 We R ighted V a . Vd . mean .... 1-46-24 -24-00 oo - -28 Curv adial v< ature , ?locitv . . , + 22'0 1909. Feb. 13. G. M. T. 12 h 53"' /3 ORIONIS 2280. Observed byl T a Pr V<5KF , TT Measured by/' J ' ^ FLASKLTT - Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rov"" Velocity. 2 63 3520 2 58-8035 2 61-3710 2 36-1748 3 2 61 3192 59-7314 2940 7105 1135 1140 + 46-92 46-64 1 36-1848 2042 1137 + 39'85 Weighted mean . . . , ... . + 45 ' 65 V a -24-00 Vd '00 Curvature ... - ' 28 Radial velocity.. + 21-4 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 1909. Feb. 20. (J. M. T. 12 h 29 ORIOMS 2284. Wt. Mean of Settings. Corrected Star Settings. Disp 4 in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. 9 03-3507 2 58-8010 2 Cl'3086 2 36-1520 ;; 3 1 61-2988 59-7346 3100 '7440 0977 1202 + 40-27 49-33 2 36-1728 1730 1249 + 4S-7& Weighted mean + 42' 95 V a -24-82 V d - "08 Curvature '28 Radial velocity +17'7 ft ORIONLS 2285. 1909. Feb. 20. Observed by\ T p TAair _, G. M. T. 13" 05'" Measured by J J - S - PLASKETT - Wt. Mean of Settings. Corrected Star Settings . Disp' in rev ns Velocity. Wt. Mean of Settings. Corrected Star Settings . Dispt in rev na Velocity. 2 2 2 1 63-3177 61-3352 61-2860 59-7262 M tOfc* K*- 58-7696 36-1246 36-1377 3278 7665 1155 1427 + 47-61 58-21 1653 1172 + 41-08 Weighted Rad $ ft ORIONIS 22* 1909. Feb. 20. G. M. T. 15 h 12 mean r + 47-79 V a - 24-82 08 28 Vd - Curvature ial velocity _ + 22 6 KETT. 56. Observed by\ T s p Measured by I' y ' ^ LAS Wt. Mean of . Settings. Corrected Star Settings . Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings . Disp* in rev" 8 Velocity. 2 63-3440 2 58-7989 2 61-3648 2 36-1571 2 1 61-3160 59-7233 3320 '7245 1197 1007 + 49 34 41-08 H 36-1733 1684 1203 + 42-16 Weighted mean + 45 ' 14 V - 24-82 Vrf - '08 Curvature - '28 Radial velocity + 19'8 360 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 1909. Feb. 21. G. M. T. 12" 57"> ft ORIONIS 2288. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev"" Velocity. Wt. Mean of Settings. Corrected Star Settings . Disp 1 in rev"" Velocity. 2 63'3644 2 58'8118 2 61 '3779 2 36-1550 2 i 61 3268 59-7422 3250 7400 1127 1162 + 46-45 47'40 1 3b-1798 1770 1770 + 45' 18 Weighted mean + 46.45 V a - 25-04 Vd - '09 Curvature... . - '28 Radial velocity. ft ORIONIS 2289. + 2i'0 1909. Feb. 21. Observed by| T ^ p _..,.,,,, G. M. T. 13" 07 m Measured by j' Wt. Mean of Settings. Corrected Star Settings . in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings Disp' in rev"" Velocity ' 2 2 2 1 63-&543 61-3695 61-3040 59-7518 I 2 58-8071 36-1572 36-1726 3105 '7545 0982 1307 + 40-48 53-39 1676 1195 +4l'i Weighted Rac /S ORIONIS 229 1909. Feb. 21 G. M. T. 13 h 17'" mean + 45-6-2 V 25-04 09 28 Curvature ial velocity + 18-2 * 0. Observed by \ T c p Measured by J J ' &> rLAS Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp 1 in rev"' Velocity. 2 63 3632 2 58-8130 2 61-3830 2 36-1631 2 1 61-3238 59 7450 3200 7415 1077 1177 + 44 39 48-01 2 36-1767 1658 1177 + 41-25 Weighted mean +43'86 V, -2504 V d - 'OH Curvature '28 Radial velocity +18'4 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 361 1909, Feb. 21. G. M. T. 13"27 m ORIONIS 2291. Observed by | r s Measured by r j - b - Wt. Mean of Settings. Corrected Star Settings. Disp* in rev 119 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev ns Velocity. 2 63'3650 2 58-8109 2 61 ' 3777 2 36-1475 3 I. 1 , 61-3190 59 7433 3170 7410 1047 1168 + 43 16 47'64 2 36-1659 1706 1225 + 42-94 Weighted mean V a ^-44-13 -25 04 Vd ........... - -09 Curvature. . . - "28 Radial velocity. + 18-7 I'.io'.t, Feb. 22. G. M. T. 12 1 ' 02" ORIOXIS 2292. Observed byT. H. PAKKKK. Measured by J. S. PI.AXKKTT. , Mean of Settings. i ( '^ ted Disp' setting*. : inrevi " Velocity, j Wt. Mean of Settings. Corrected Star Settings. . Di *P' n , Velocity, in rev"* j 2 63-3642 2 58-8102 j i 2 61-3755 2 36-1595 2 j 61-3167 59-7493 3157 -1034 7483 '1245 + 42-62 50-78 1 1 36-1831 1758 1277 +44-76 Weighted mean V a -25-14 - -02 Curvature ... - "28 Radial velocity + 19 ' 7 ORTONIS 2293. 1909, Keb.22 Observed by T. H. PARKER. G. M. T. 12 h 15'" Measured by J. S. PLASKKTT. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev"" Velocity. Wt. Mean Corre Of St Settings. Settii fd Dispt ' lg s. in rev '" Velocity. 2 2 2 1 63-3503 61-3637 61-3018 59-7474 2 2 i 58-8000 . 36-1558 .. . . . . i ^125 '7570 1002 1332 -f-41 30 54-33 36-1807 'I 771 '1290 + 45-21 Weigl ited mean t- 45-58 V a -25'14 Vd 02 Curvature. . Radial velocity. . . .. - '28 t-25'1 362 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 191G 1909. Feb. 22. G. M. T. 12 h 30 m /3 ORIONIS 2294. Observed by T. H. PARKER. Measured by J. S. PLASKETT. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev 118 Velocity, j Wt. Mean of Settings. Corrected Star Settings. Dispt in rev" 8 Velocity. 2 63 '3495 2 58 ' 8022 2 63 '3678 2 36-1610 2 61-3121 3210 1087 + 44-81 2 36-1809 1720 1239 -i 43 43 14 59-7381 7458 1220 49'76 Weighted mean + 45 ' 66 V a -25-14 Va - -02 Curvature - "28 Radial velocity + 20'1 (3 ORION IS 2295. 1909- Feb. 22. Observed by T. H. PARKER. G. M. T. 12 h 42 ra Measured by J. S. PLASKETT. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. 2 2 2 2 63 3622 61 3780 61-3248 59-7345 2 2 H 58-8095 36-1677 36 1881 3280 '7344 1157 1106 + 47-69 45-11 1726 1245 + 43'64' Weighted mean + 45 ' 65 V a -25-14 Vd '02 Curvature - '28 1909. Feb. 27. G. M. T. 11" 35" Radial velocity +20'2 /3 ORIOXIS 2309. Observed byl T o p Measured by/ J< b " FLAS>KETT - Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" s Velocity 2 63 3682 2 58'8129 2 61-3790 2 36-1491 2 H 61-3288 59-7498 3240 7460 iii7 1222 + 46-04 49-85 2 36-1814 1845 1364 + 47 ?1 Weighted mean , + 47 ' 71 V a -25-48 V d '00 Curvature . . - '28 Radial velocity +22 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 363 1909. Feb. 28. <;. M. T. Il h 56" ORIONIS 2311. Observed by\ T q p rA , KItTT Measured by/ ' &> "ASKBTT. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev 118 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. 2 63-3272 2 58 '7792 9 63-3402 2 36-1567 2 I* 61-2899 59-7215 2940 7250 1135 1285 + 46-92 52-63 H. 36-1805 2180 1275 + 44-83 Weighted mean + 48 ' 01 V tt -25-53 V d - -02 Curvature... - '28 Radial velocity .. .. +22'2 ORIONIS 2312. 1909. Feb. 28. Observed by \ T , p G. M. T. 12" 07 m Measured by / J ' Wt. Mean of Settings. Corrected Star Settings . Disp* in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings . Disp' in rev" s Velocity. 2 2 3 2 63-3345 61-3567 61-2980 59 7342 2 2 2 58-7913 36-1739 36-2048 2890 7260 1085 +44-85 1295 53-04 2251 1346 +47 33 Weighted Rad /3 ORIONIS 231 1909. Feb. 28. G. M. T. 12 h 18 m mean -i 47 90 V -25-53 - -02 - '28 Curvature ial velocity. -4 22 3. Observed by) T ^ p Measured by /* FLAS Wt. Mean of Settings. Corrected Star Settings . Disp 1 in lev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings . Disp 4 in rev" 8 Velocity. 2 2 2 1 63 3394 61 3602 61-3112 59-7515 2 2 1 58-7911 36-1740 36-1806 .-3000 7435 1195 1470 + 49-40 60-21 2026 1121 + 39-41 Weighted mean + 49-61 V a . . . . -25-53 - -02 V*.. Curvature Radial velocity. + 23-7 364 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 ORIONIS 2314. 1909. Feb. 28. G. M. T. 12 h 27" Observed byl T p. Measured by / J< Sl FL Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star ' Settings . Dispt in rev 1 " Velocity. 2 63-3298 2 58 '7866 2 61-3467 2 36-1742 2 li 61-3037 59-7434 3005 7408 1200 1443 + 49-61 59-11 H 36-1998 2198 1293 - 4.V-K! Weighted mean + 51 ' 22 V a -25-53 Vd - -02 Curvature . . '28 1909. Feb. 28. G. M. T. 12 h 39 m Radial velocity +25'3 ORIONIS 2315. Observed byl T p r ,,,., Measured by J J - b ' ^ LASKETI - Wt. Mean of Settings. Corrected Star Settings . Disp* in rev"" Velocity. Wt. Mean of Settings. Corrected Star Settings . Disp in rev ns Velocity 2 63-3247 2 58 7759 2 61-3422 2 36'154l 3 H 61-2979 59-7148 3005 '7215 1200 1250 + 49-01 51-14 2 36-1757 2158 1253 + 44 06 Ra< p ORIONIS 23 1909. Feb. 28. G. M. T. 12 h 50 m V a Vrf - 25-53 - 02 - '28 Curvature lial velocity. 1-22-4 KKTT. L6. Observed byl T ^ p Measured by J' K b> 1 LAS Wt. Mean of Settings. Corrected Star Settings. Disp 1 in rev 1 " Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev 11 " Velocit 2 2 2 li 63-3355 61-3528 61-2998 59-7455 o <> ii 58-7887 36-1782 36 1944 "2920 7400 1115 1435 + 46-09 58-71 . 2105 1200 +42-1 Weighted Ra< . mean h 48-71 V .. -25 53 02 - '28 Vd Curvature lial velocitv -22-8 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 365 1909. Mar. 2. G. M. T. ll>> 20" j8 ORIONIS 2317. Observed by) T Measured by/ J< p f AHirFTT ^ LASKK1T - Wt Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt Mean of Settings. Corrected Star Settings. Disp' in rev" 8 . Velocity. 63 3647 2 58'8147 o 61 '3807 2 36-1744 2 6f3360 59-7707 3320 '7655 1197 1417 + 49-34 57-80 H 36-1960 1738 1257 + 44-06 Weighted mean +50'97 V a ...., -25-61 Va - -02 Curvature - '28 Radial velocity .................... +25'9 1909. Ma-. 2. G. M. T. II 1 ' 19" p ORIONIS 2318. Wt, Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Dispt in rev" 8 Velocity. o 63 3626 2 59-8075 2 61-3804 2 36 1516' 2 2 61 3217 59-7622 3210 7t34<) 1087 1402 + 44-81 57-19 11 36-1860 1866 1385 + 48 54 Weighted mean +50'33 Va -25-61 Va -02 Curvature. . - '28 Radial velocity + 24 " 4 1909. Mar. 2. (i. M. T. ll h 29' n ft ORIONIS 2319. Observed byl T Measured byj J ' Wt. Mean of Settings. Corrected Star Settings. Disp 4 in rev n " Velocity. Wt. Mean of Settings. Corrected Star Settings. in rev na Velocity. 2 2 2 H 63-3438 61-3600 61-3090 59 7476 2 2 2 58-7920 36-1442 36 1763 . 3200 7650 1137 1412 + 46-87 57-59 1843 1363 + 47-77 Weightec Ra mean f 50-12 V a -25-61 02 - '28 Curvature dial velocity. + 24'2 366 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 )8 ORION IS 2320. 1909. Mar. 2. Observed by } i , g p. ...__ G. M. T. Il h 36 m Measuied byf ' Wt. Mean of Settings. Corrected Star Settings. Disp 1 in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star > Settings. Disp 4 in rev ns Velocity.! 1 2 2 2 U 63-3522 01-3707 61-3197 59-7315 2 2 2 58 7996 36-1541 36-1921 3290 7312 1167 1074 4-48-10 43-81 1902 1421 + 49-8if Weighted mean V a -25-61 Vd - -02 Curvature.... - '28 + 47-55 1909. Mar. 13 G. M. T. 12 h 12" Radial velocity. j8 ORION IS 2364. -21-6 Wt. Mean of Settings. Corrected Star Settings. Disp' in rev n " Velocity. Wt. Mean cf Settings. Corrected Star Settings. Disp' in rev ns Velocity 2 63-3696 2 58' 81 15 2 61-3870 2 36-1448 2 11 61-3327 59-7380 3250 7320 1127 1082 + 46 5 44-1 li 36-1611 1685 1204 +42-; Weighted mean + 44 ' 50 V a -25-45 Vd - -16 Curvature... "28 1909. Mar. 13 G. M. T. 12 h 24 m Radial velocity +18'6 j8 ORION IS 2365. Observed by \ T q Measured by/' J ' b ' Wt. Mean .of Settings. Corrected Star Settings. Disp* in rev 08 Velocity. Wt. Mean of Settings. Corrected Star Settings. 2 Disp' in rev 118 Velocity 2 63-3760 2 58-8161 2 61-3876 2 36-1348 3 2 61-3228 59-7507 3120 7425 0997 1187 + 41'1 48-4 li 36-1591 1765 1284 + 45' Weighted mean + 44 ' 25 V ffl -25-45 Va - -16 Curvature.... - '28 Radial velocity + 18 - 4 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 367 1909. Mar. 13 G. M. T. 12 h 36 ft ORIONIS 2366. Observed by \ T PrASKRTT Measured by J J> &> rLAS Wt. Mean c.f Settings. Corrected Star Settings. Disp* in rev ns Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. 2 63-3662 | 2 53-8112 2 61-3821 2 36-1400 2 61-3198 59 7506 3160 7475 1037 1237 + 42'7 50-4 li 36-1692 1814 1333 +46'7 Weighted mean V n + 46-21 -25-45 Va- - '16 Curvature.... - '28 Radial velocity +20'3 ft ORIONIS 2367. 1909. Mar. 13. Observed by \ T q Pr G. M. T. 12" 46'" Measured by / J ' b ' ^ LASKE "- Wt. Mean of Settings. Corrected Star Settings. Dispt in rev" 9 Velocity. Wt. Mean 9 f Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. h-" tO tO tO tar-tar- 63-3600 61-3738 61 3086 59-7297 2 58-7981 36 1272 36-1460 3125 7400 1002 1162 + 41 30 47 40 1710 1229 + 43-10 Weight I ft ORIONIS 23( 1909. Mar. 13. G. M. T. 12 h 57 m ed mean - h43 45 V a -25-45 - -16 - '28 Curvatu ladial velocit; 8. C It re f 1-17-6 ASKETT. >bserved by ) j & p leasured by / Wt. Mean of Settings. Corrected Star Settings Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. 2 2 2 2 63-3640 61-3800 61-3300 59-7306 2 58-8093 36-1354 36-1578 3280 7300 1157 1062 + 47'7 43 3 1746 1265 + 44-3 Weight B 25a 26 ed mean -I -45-17 V ffl ... -25-45 - -16 - -28 Vd Curvatu uadial velocity re T -{ -19-3 368 DEPARTMENT OF THE INTERIOR 1909. Mar. 15. G. M. T. ll h 45"' ft ORIONIS 2372. 9-10 EDWARD VII., A. 1910 Observed by } T ^ p T ., Measured by /'' b> A LASKE1 r - Wt. Mean of Settings . Corrected Star Settings . Disp 1 in rev" 9 Velocity. Wt. Mean of Settings . Corrected Star Settings . Dispt in rev*" Velocity. 2 63 '3472 t 58-8015 2 61-3664 2 36 1624 2 1 61-3098 59-7205 2890 7015 1085 1050 -4-44-85 42-96 li 36-1712 2030 1125 + 39 55 Weighted mean .... + 42 ' 66 V a -25-34 V d '14 Curvature "28 1909. Mar. 15. G. M. T. 11" 56" Radial velocity + 16'9 ORIONIS 2373. Observed by\ T p .___ Measured by / J - b " FLASKETI - Wt. Mean of Settings. Corrected Star Settings . Disp* in rev" 8 Velocity. Wt. Mean of Settings . Corrected Star Settings . Disp f in rev" 8 Velocity. 2 63-3475 2 58 7985 2 61-3660 2 36 1478 f 61-3094 59-7421 2890 7260 io85 1295 + 44-85 52-98 H 36-1697 2161 1256 + 44-16 Weighted mean + 46 ' 27 V a -25-34 Yd -14 Curvature ... - ' 28 Radial velocity +20'5 1909. Mar. 15. G. M. T. 12 1 - 05'" j8 ORIONIS 2374. Observed by) r , Measured \>y )' Wt. Mean of Settings. Corrected Star Settings. Disp 4 in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 9 Velocity 2 63 3415 2 58 '7942 2 61-3612 2 36'1598 2 1 61-2924 59-7336 2764 7220 0959 1255 + 39-65 51-34 li 36-1784 2128 1223 + 43-W Weighted mean + 43 ' 36 V a -25-34 V d '14 Curvature... - '28 Radial velocity +17'6 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 369 1909. Mar. 15. G. M. T. 12 1 ' 13" j8 ORIONIS 2375. Observed by I T s Vr A <, KR TT \r j t i \ V O. JL L,AoKH( 1 J . Measured by J Wt. Mean of Settings. Corrected Star Settings. Disp 1 in rev" Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev"" Velocity. 2 63 '3430 2 58'7960 2 61 3618 2 36-1654 2 H 61-3146 59-7102 2976 6972 1171 1007 + 48-41 41 20 1| 36-1837 2125 1223 + 43-00 Weighted mean +44'62 V a -25-34 V d - -H Curvature. . "28 1909. Mar. 15. G. M. T. 12>> 21" Radial velocity + 18'9 ft ORIOXIS 2376. Observed by \ V K p TA , KItT . r Measured by/ J ' * FLASKKTT - Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. 63-3492 > 61 3678 2 61-3032 59-7281 2800 7088 0995 1123 + 41-13 45 94 Wt. Mean of Settings. 58-8022 36 1743 36-1771 Corrected Star Settings. Disp' in rev" 1970 1065 Velocity. +37-45 Weighted mean +41 '92 V a -25-34 Vd -14 Curvature. . . "28 . Radial velocity +16'2 1909. Mar. 18. G. M. T. 11M2" ft ORIONIS 2386. Observed by \ T Measured byT' Wt. Mean of Settings. Corrected Star Settings. Disp' in rev"" Velocity. W T t. Mean of Settings. Corrected Star Settings. Disp' in rev 1 " Velocity. 2 63-3427 2 58 7936 2 61-3610 2 36-1518 . 3 o 61-3020 59-7188 "siso 7846 1062 1108 + 43-78 45-20 1 36-1820 1824 1313 + 47'07 Weighted mean +44'98 V a -25-09 , Vd '15 Curvature. . "28 25a Radial velocity. ...' +19'5 370 1909. Mar. 18. G. M. T. Il h 52 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 8 ORIONIS 2387. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 3 Velocity. 2 63 '3645 2 58-8071 \ 2 61-3782 2 36-1581 2 61-3205 59-7465 3200 7480 1077 1242 + 44 39 50-66 1 36-1684 1625 1144 + 40-10 Weighted mean + 45 - 53 V a -25-09 Vd - '15 Curvature... - '28 Radial velocity +20'0 1909. Mar. 18. G. M. T. 12 h 02 m /3 ORIONIS 2388. Observed by ) T , p rACJK . PTT Measured by f ' ^ ^ LASKETT ' Wt. Mean of Settings. Corrected Star Settings. Disp' in rev ns Velocity. Wt. Mean of Settings. Corrected Star Settings. Dispt in rev 1 "V elocity. 2 63'3541 2 58-8001 2 61-3718 2 36-1635 2 14 61-3210 59 7396 3280 7480 1157 1242 +47-69 50-66 11 36-1828 '1715 1235 + 43-29 Weighted mean + 47 ' 26 V a -25-09 Vd - -15 Curvature. . . - "28 Radial velocity + 21 7 1909. Mar. 18. G. M. T. 12 h 12 m j8 ORIONIS 2389. Observed by \ T ^ p .,, TiT J 1 f V t fjt JL LAoh-Kl 1. Measured by ) Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. 2 63-3492 2 58T998 2 61-3646 2 36-1597 ? 61-2927 59-7380 3050 '7485 0927 1247 + 38-21 50-86 H 36-1954 1879 1398 + 49-00 Weighted mean +46'51 V a -25-09 Va- - -15 Curvature - '28 Radial velocity +21'0 REPORT OF THE CHIEF -ASTRONOMER SESSIONAL PAPER No. 25a 371 1909. Mar. 20. G. M. T. 12 16 j8 ORTONIS 2390. Observed by "1 T T>T . Measured by JJ- S. PLABKETT. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev 118 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev 118 Velocity. 2 63 3657 2 58-8128 2 61'3836 2 36-1496 2$ ll 61-3307 59-7601 3260 7561 1137 1323 + 4fc86 53-96 14 36-1655 1681 1200 + 42-06 Weighted mean . V a V d Curvature . -24-88 12 - '28 + 4 7'49 Radial velocity +22'2 (8 ORIONIS 2391. 1909. Mar. 20. Observed by \ T q p ., G. M. T. 12" 26 m Measured by / J ' b ' rLAS Wt. Mean of Settings. Corrected Star Settings. Disp 4 in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 9 Velocity. 2 2 2 14 63-3724 61-3859 61 3292 59-7392 t 2 2 ii 58-8192 36-1414 36-1637 3192 7292 1069 1054 + 44-06 42-99 1745 1264 + 44-30 Weight Radial ed mean - ^ 43-81 V a -24-88 - -12 - '28 Curvature velocity . . . . +18-3 f3 ORTONIS 2:592. 1909. Mar. 20. Observed by^ , , p rASKFrrT G. M. T. 12 h 38 m Measured by/ J ' & Wt. Mean of Settings. Corrected Star Settings. Dispt in rev"" Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev ns Velocity. 2 2 3 li 63-3775 61-3892 61-3352 59-7575 2 2 2 58-8197 36-1569 36 1862 -3320 7460 iJ97 1222 + 49 34 49-85 1815 1334 + 46-76 Weighted mean + 48 ' 66 V a -24-88 Vd - -12 Curvature "28 Radial velocity +23'4 372 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 1009. Mar. 20. G. M. T. 12 h 48" /3 ORION IS 239S. Observed by \ T <, Measured by/ J - b ' Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev"' Velocity. 2 63 '3059 2 58-8108 2 61-3800 2 36-1480 2 14 61-321f. 50-7468 3184 7448 1061 1210 + 43-73 49-36 i* 36-1857 1900 1419 + 49.74 Weighted mean + 47 ' 22 V a -24-88 V d '12 Curvature... - '28 Radial velocity +21'9 ORIONIS 2394. 1909. Mar. 20. G. M. T. 12 h 58" Observed by Measured by Wt. Mean of Settings. Corrected Star Settings. Disp 1 in rev" 9 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" s Velocity. 2 63'3661 2 58-8130 2 61-3815 2 36-1565 2i 61 3319 3275 1152 + 47-49 U 36-1806 1763 1282 + 44-93 3 59-7587 7547 1309 53-39 Weighted mean +48'40 V a -24-88 Va - -12 Curvature ... - ' 28 Radial velocity +23' 1 1909. Mar. 21. G. M. T. 13 h 38" ft ORIONIS 2397. Observed by \ T s v rAHKKTT j \ ft.'. O. T IjAoKr*! I. Measured by } Wt. Mean of Settings. Corrected Star Settings. Disp* in rev" s Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev 118 Velocity. 2 63'3695 2 58-818!) 2 61 ' 3856 2 36-1752 2 2 61-8328 59-7550 3240 7460 1117 1222 + 46-07 49-83 14 36-2220 1990 1509 + 52-89 Weighted mean +49-30 V a -24-76 Va - '32 Curvature - '28 Radial velocity + 23-9 REPORT OF THE CHIEF ASTRONOMER 373 SESSIONAL PAPER No. 25a 1909. Mar. 21. G. M. T. 13 h 48"' ORIONIS 2398. Observed by \ T Measured by/ J ' Wr. Mean of Settings. Corrected Star Settings. Disp' in rev" 9 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev 118 Velocity. 2 63-3667 2 58-8120 2 61-3818 2 86-1571 2 2 61-33% 59 7441 3850 7410 1227 1172 + 50-60 47-81 2 36-2053 2004 1523 + 53-38 Weighted mean. V..".. + 50-60 Curvature . -24 76 - "32 - -28 1909. Mar. 21. G. M. T 14" Radial velocity. ... +25'2 OKIONIS 2399. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev"" Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev 1 Velocity. 2 63-3483 2 58 '7972 2 61-3664 2 36-1511 ' 2 2 61-3124 59-7452 3245 '7572 1122 1334 + 46-27 54 41 1 36-1884 1894 1414 + 49-56 Weighted mean +50'18 V -24 76 Vd - -32 Curvature - '28 1909. Mar. 21. G. M. T. 14" 14' Radial velocity +24'8 /3 ORIONIS 2400. Wt. Mean of Settings. Corrected Star Settings. Disp 1 in rev"" Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. 2 63-3505 9 58-8071 2 61-3712 Wt. Mean of Settings. Corrected Star Settings. Dispt in rev" 8 Velocity. Wt. Mean of Settings. Corrected - Star Settings. Disp' in rev" 8 Velocity. 2 63 '3584 2 58-8043 61 "3737 2 36-1447 2 61-3370 3410 1287 + 53-05 H 36-1712 1787 1307 + 45-81 li 59-7510 7560 1322 53-92 Weighted mean + 51 ' 14 V a -24-66 Vd - -16 Curvature . . - '28 Radial velocity +26'0 ft ORIONIS 2403. 1909. Mar. 22. G. M. T. 12 h 02" Observed by } T Measured by / Jl Wt. Mean of Settings. Corrected Star Settings. Disp* in rev"" Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. 2 63-3517 2 58-8009 2 61-3688 2 36-1536 *2 1* 61-3260 59 7423 3355 7573 1232 1275 + 50-78 52-01 !i 36-1846 1832 1832 + 47-36 Weighted mean + 50' 12 V a -2466 V d - '16 Curvature - '28 1909. Mar. 22. G. M. T. 12 h 13 m Radial velocity +25'0 ft ORIONIS 2404. Observed by \ T , p .,., Measured by ) J ' S< FLASKKTT - Wt. Mean of Settings. Corrected Star Settings. Dispt in rev" 8 Velocity. Wt. Mean ** Settings. Corrected Star Settings. Disp in rev" 8 Velocity. 2 63-3608 2 58*8094 2 61-3126 2 36 "1640 2 n 61-3242 59-7329 3260 7335 1137 1107 + 46-87 45-15 H 36-1917 1800 1319 + 46-23 Weighted mean +46'16 V a -24-66 Vd - -16 Curvature . "28 Radial velocity +21'1 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 375 1909. Mar. 22. G. M. T. 12 h 35 j8 ORION IS 2405. Observed by \ y Measured by |' K * Wt. Mean of Settings. Corrected Star Settings. Dispt in rev 118 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp 4 in rev 118 Velocity. 2 63 3570 2 58-8019 2 HI 3713 2 36-1480 H 613138 59-7375 3228 7450 1105 1212 + 45-55 49-44 i* 36-1698 1740 1259 + 44 13 Weighted mean +46'29 V a -24-66 Vtf - -16 Curvature . . - ' 28 Radial velocity .................. +21'2 1909. Mar. 23. G. M. T. ll h 46" P ORIONIS 2420. Observed by ) T Measured byj J> Wt. Mean of Settings. Corrected Star Settings. 1 isp* in rev 119 Velocity. | Wt. Mean of Settings. Corrected Star Settings. Dispt in rev" 9 Velocity. 2 63-3586 2 58-8059 2 61-3757 2 36-1332 li l| 61-3160 59 7445 3190 7480 1067 1242 + 43 99 50-66 2 36-1699 1889 1408 + 49-35 Weighted mean .......... ........... +48'14 V ................. - 24-54 Curvature . '19 '28 1909. Mar. 23. G. M. T. ll 1 ' 57" Radial velocity +23'1 ORIONIS 2421. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp* in rev 118 Velocity. 2 63-3700 2 58-8151 2 61 3800 2 36-1310 t-'lxS K>-Ki- 61-3418 59-7447 -3358 7390 1235 1152 + 50-92 49-99 2 36-1608 1820 1339 + 46-93 Weighted mean +49'36 V a - 24-54 V d '19 Curvature - '28 Radial velocity. + 24-4 376 DEPARTMENT OF THE INTERIOR 1909. Mar. 23. G. M. T. 12'- 05" /3 ORIONIS 2422. 9-10 EDWARD VII., A. 1910 Observed by \ T , p r . SKKTT Measured by J b ' ^ LASK Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. Wt. Mean of Settings. Corrected Star Settings. > Disp' in rev" 8 Velocity. 63 -3572 2 58'8081 61 ' 3728 2 36-1372 2 61 3253 3290 1177 + 48-53 2 36-1920 2070 1589 + 55 69 1 59-7348 7370 1132 46-17 Weighted mean. V a Curvature. . . Radial velocity -24 54 19 - -28 + 25 9 1909. Mar. 23. G. M. T. l:i h 13" ft ORIONIS 2423. Observed by \ T s p . SK ,..., Measured by ) J ' fe ' FLAfeKE 1 1 Wt. Mean of Settings. Corrected . Star Settings. Disp' in rev Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity. 2 63 3787 2 58-8225 2 61-3936 2 36-1500 2 2 61-3330 59 7696 3170 7551 1047 1313 +43-17 53-56 2 36-2082 2104 1623 + 56-89 Weighted mean + 51 ' 21 V a - 24-54 Vd ' - '! Curvature.. '28 Radial velocity +20'2 1909. Mar. 23. G. M. T. 12 h 27'" ORIONIS 2424. Observed by J. B. CANNON. Measured by J. S. PI.ASKKTT. Wt. Mean of Settings Corrected Star Settings. Disp* in rev"" Velocity. Wt. Mean of Settings. Corrected Star Settings. Disp' in rev" 8 Velocity 2 2 H if 63 3774 61-3930 61-3425 59 7590 2 2 2 58-8212 36-1341 36-1822 3275 7465 1152 1227 + 47-51 50-35 1997 1516 + 53 14 Weighted V V c Radial velc nean fSO'52 -24 54 2S > 38" ,3 ORIONIS 2425. Observed by J. B. CANNON. Measured by J. S. PLASKETT. Wt Mean of Settings. Corrected Star Settings. Disp' in rev 1 " Velocity. Wt. Mean of Settings. Corrected Star Settings . Disp' in rev 1 " Velocity. 2 63-3650 2 58-8098 2 61 3793 2 36 1269 2 14 61-3350 59-7498 3327 7490 1204 1252 + 49-65 51-07 H 36 1707 I960 1479 -i-51'84 Weighted mean +50' 72 V a -25-54 Vd - -19 Curvature.. . - "28 Radial velocity +25'7 378 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 191'J OQ 1 S 1 . I-H 05 T3 Q o ,^ sqo rtrtrtr- rt 1-. w PnO-itHMHHH tc T3 ^ :'.'.:. 3 'S 01 8 :' : ' ' o'pl - - '' ^-g NTK r-0>00t- .0 T|H--COO 50U5.0 CD 10 ' (N IN (N CQ CO i w 3 S O O C OO j S o lOrH O>OC*5'*<-a^ieio^ioioeooio 1O-* OO O HH 5? -ut'Saa !0(N 1-UON^lCTtib.oOt-OSi-Hl^.OiOCOO^f-iNi-l O CO -f CO "*3 02 H fe "bC ... 3 9 "X PH O * N N f5 rH 1 1 * r- 1 O I 1 N IN O Tf I-H lO O O CC 3 R S Q I . . O o,^ na S.-ih- O(NlOiOOOCliOOOOOOmiMlN-i < C<5 * M IN IN W* CC * M< fO CO C<5 C C<5 * ^ W IM o CO -V O f t^ w'^ 43 ' JH t 1 1 INOO iOOOCCiCINe^^l-*^^ CC O X O 1-i CM C ? p 10 o o o m ao < ( w o ^0 aJ31-^-* l> I. IC^rH = r r : r ~ u " N 1-1 N rHOt-lr-l ^rHC^COC^ 3S8 8939 ot>-i--xoi -lrH^-lrHrH E* Sj *O O lA lO b- 1^ l^ 35 O O O i-i ^H r- ff C ? 08 ?( tCO OO 00 r-ti-ISiNe777 Weighted mean - 44 13 V a +15 01 Vd + -04 Curvature - ' L'8 Radial velocity - 29'0 25a 27 384 DEPARTMENT OF THE INTERIOR 1908. June 22. G. M. T. 18 h 35" 6 AQUTLJE 1626.' 9-10 EDWARD VII., A. 1910 Observed by T. H. PARKER. Measured by J. B. CANNON. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revns. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revns. Velocity. 1 57 "8369 . 37-7667 7262 0383 -36-92 0* 57-8165 o4 ' 7682 8025 0243 -29-26 2 29-8124 29-6441 7624 oea^ -60-90 2 53 9534 53 ' 1347 9294 0404 -46-50 1 9, 27-4266 27-3062 3746 0380 -32'98 2 45 ' 3077 ?, 11-8604 7864 0650 -48-68 11 45 ' 2463 2123 0264 -27'56 ?, 11-5823 *2 2 38*9962 *Check measurement. Weighted mean - 41 03 V a +15-01 Vd + '04 Curvature - '28 Radial velocity - 26 3 1908. June 24. G. M. T. 19 h 46" 6 AQUIL^E 1634. Observed by | WEHR Measured by J Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Kevns. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revns. Velocity. 9 57-9245 1 37-8255 7200 0347 -33-45 X 57 8639 "7688 '0580 -69'83 2 30'0385 2* 54-8105 1 29-8974 7819 0490 -43-56 3 o 54 0327 53-2094 9347 0351 -40-40 J J 27-4733 27 '3638 3561 0565 -49-04 ?, 45-3719 n 11-9231 8011 -0503 -37 67 2 45-2924 1941 '0446 -46'56 8 s 11*6292 ?, 3S-0650 Weighted mean - 42 ' 95 V a +14-12 Vd - 06 Curvature - '28 Radial velocity - 29'2 385 SESSIONAL PAPER No. 25a 1908. June 26. (*. M. T. 19M2 m AQUILJE 1643. Observed by T. H. PARKER. Measured by W. E. HARPER. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revns. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revns. Velocity. 57 '8751 fl 38-0110 2 o 57-8285 54 7850 7742 0526 -63-33 2 1 37-7647 27 4172 7131 3588 0416 0538 -40 10 -46'70 53 ' 9798 '9370 0328 -37'75 9, 27-3150 2 53 ' 1545 8 11-862!) '8040 '0474 -35'50 2 45-3026 7! 11-C661 2 45-2498 2008 0379 -39-57 Weighted mean -42'90 V a +13-22 V d - -09 Curvature - '28 Radial velocity -30'0 1908. June 27. G. M. T. 18 h 45" 6 AQUIL^E 1651. Observed by J. S. PLASKETT. Measured by W. E. HARPER. ft. Mean of Settings. Corrected Star Settings. Displace- ment in Revns. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revns. Velocity. 3 57'8(i40 1 30-8717 8126 0630 -56-57J 1 57 ' 8292 '7946 0322 -38'77 9 29-6583 -> 54 '7825 1 29-6105 5510 0479 -42-53 9 53-9715 53-1535 9320 0378 -43-51 i 27-4256 27-3135 3590 0536 -46'52 2 45-3175 H 15-4903 4182 0551 -42-65 ]! 45 -2365 '1926 '0461 -48 13 2 15 '4707 o- 38'0075 3 11-8646 '7958 0556 -41-64 1 37 ' 7459 '6973 '0554 -53 40 9 11-5760 " 30 9295 Weighted mean -45'06 V a +12-83 Vd -00 Curvature - "28 Radial velocity. -32-5 25a 27* 386 DEPARTMENT OF THE INTERIOR 190S, July3. G. M. T. 17 h 30" AQUILvE 1659. 9-10 EDWARD VII., A. 19': Observed by W. E. HARPER. Measured by J. B. CANNON. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revns. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revns. Velocity. 2 54'6001 2 11-6263 11-7883 0631 -47'26 rcq-TQOi 53 '9309 '0389 -44-77 9 11-3448 2 52 '9687 - Weighted mean ; . . 46" 01 V a +10-32 Vd -00 Curvature. . . '18 1908, July 8. G. M. T. l h 49" Radial velocity - 35'9 AQUILJE 1679 Observed by ^y. E. HARPER. Measured by J. B. CANNON. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings. Settings. Revns. Settings. Settings. Revns. 1 73-1291 ?! 45-3990 1 72 '9478 8298 0350 -50-78 1 45-3177 1923 0464 -48 44 1 72 '5626 1 27-4959 3539 0587 -50-959 2 54 '8610 fl 27-3903 2 54-0581 9390 0308 -35-45 1* 11-9333 '7803 0711 -53 25 2 53'2311 a H'6602 Weighted mean - 46 ' 30 V a +8'05 Va- -01) Curvature ... ' 2S 1908. July 10. G. M. T. 19" 30 Radial velocity - 38"6 AQUILJE 1691. Observed byl T Measured by/ 1 ' Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in "Velocity. Settings . Settings . Revolutions. Settings. Settings . Revolutions. 2 72'9970 H 63-9308 9368 0330 -37 98 A 72-8227 8352 '02% - 42'94 J* 53-1036 I 1 72 4327 2 45-2729 2 57-7960 | 45-1767 1777 0610 -0368 1 57-7501 7831 0463 -55-74 ! 27-3741 3471 0655 -56-85 2 56-6372 2 27 '2739 2 54'7314 I Weighted mean -48 '88 + 7-14 Va - -12 Curvature -2S Radial velocity . . -42 1 REPORT OF THE CHIEF ASTRONOMER 387 SESSIONAL PAPER No. 25a 1908. July 10. G. M. T. 19 h 30 m B AQUILJE 1691*. Observed by T. H. PARKER. Measured by J. B. CANNON. Wt. Mean of Settings. Corrected Star Settings . Displace- ment in Revolutions. Velocity. Wt. Mean of Settings . Corrected Star Settings . Displace- ment in Revolutions Velocity. 1 73 0001 li 53 9446 9446 0252 -29'00 i 72 8210 8277 0371 -53'83 V 53-1121 72-4443 2 45-2831 2 57 ' 8282 li 45 1971 "1874 0513 - 53'56 1 2 57-7688 54 7417 7700 0568 -68'39 2 27-4088 27-2902 3658 0468 -39-62 Check measurement. Weighted mean .-, -47'79 V a +7-14 Vd 12 Curvature ... ' 28 Radial velocity . , 41'0 AQUIL^E 1696. 1908. July 11. Observed by J. S. PLASKETT. G. M. T. 19 h 10 m Measured by W. E. HARPER. Wt. Mean of Settings. Corrected Star Settings . Displace ment in Revolutions. Velocity. Wt. Mean of Settings . Corrected Star Settings . Displace- ment in Revolutions. Velocity. 2 1 '2 '2 2 2 57-8543 57-8215 54 7744 53-9587 53-1422 45 3096 1C ti -MO ^ 45-2351 29 6333 29 6020 11-8235 11-5325 1991 0396 -41-34 796S 0300 -36 12 5C>76 7982 0313 0532 -27 54 -39-85 9274 0424 -48-80 Weighted mean -40'40 V a +6-60 V d -12 Curvature : - '28 Radial velocity. -34 2 388 DEPARTMENT OF THE INTERIOR 1908. July 13. G. M. T. 19 h 37" 6 AQUIL^E 1704. 9-10 EDWARD VII., A. 1910 j Observed by T. H. PARKER. Measured by J. B. CANNON. Wt. Mean of Settings . Corrected Star Settings . Displace- ment in Revolutions. Velocity. Wt. Mean cf Settings . Corrected Star Settings. Displace- > ment in Revolutions. Velopity. 1 73'0441 2 53-1318 1 72 '8608 8565 '0083 -12-05 2 45-3027 1* 72 '4491 1 45-2546 2156 0231 - 24 - 12 2 57 '8483 I 27-4155 3555 '0561 -48'69 i 57'8073 '7883 038f i -46'35 ?: 27 3060 8* 54-7666 H 11-8718 '7958 '0556 - 41 ' 64 2 53-9556 9296 0402 -46-27 2 11-5838 Weighted mean -38'78 V a +5'77 V d -16 Curvature ... - ' 28 Radial velocity -33'5 1908, July 14. G. M. T. 18 h 19 n 9 AQITILJE 1708. Observed by W. E. HARPER. Measured by J. B. CANNON. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. j Velocity. ! 1 1 73-0051 2 45-2705 : 1 1 72-8307 72-4410 8351 0297 -43-09 2 U 45-2015 27 '3918 2045 3786 0342 '0430 -3T3S; 2 54-7316 2 27 '2622 2 2 53-9435 53-1072 9505 0193 -22-21 2 2 11-8489 11-5364 8199 0315 -23 58 Weighted mean -30'83 V a +5-34 v<* -oo Curvature ... ' 28 Radial velocity. REPORT OF THE CHIEF ASTRONOMER 388 SESSIONAL PAPER No. 25a 1908, July 15. G. M. T. iy h 24" AQUIL^E 1716. Observed by W. E. HARPER. Measured by J. B. CANNON. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings. Settings. Revolutions. Settings. Settings. Revolutions. 1 73-0426 2 45-3046 I 72-8798 8475 0173 -25-10 1 45-2469 2159 0228 23-80 1 72-4764 2 29-6384 57-6582 U 29-6106 5716 0273 24'22 57-8243 7943 0313 37-68 l| 27-435H 3871 0255 22 15 2 54-7774 2 27-2951 2 53-9873 9543 0155 17-84 11 11-8697 8197 0317 -23-74 2 53-1427 2 H'5523 Weighted mean - 23'88 V a +4-86 Va- - -16 Curvature '28 Radial velocity - 19 ' 5 1908, July 25. G. M. T. I6 h 29 n 6 AQUIL^E 1727. Observed by J. S. PLASKETT. Measured by W. E. HARPER. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 73 0229 2 45'2811 1 1 72-8498 72-4507 8385 0263 -38-16 2 45-2157 27 '3982 2082 3715 0305 '0411 31 84 35'7 2 54-7506 1 27-2733 2 2 53 9420 53-1227 9323 0375 43-16 fi 2 11-8282 11 5343 8011 0503 -37-67 Weighted mean -37'52 V a + '25 Va- + -04 Curvature .... ' 28 Radial velocity -37 '5 390 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 ! e AQUIL^E 1730. 1908, July 26. Observed by \ w p H . RPFR G. M. T. 17 h 38 Measured byj w ' " Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. , Displace- ment in Velocity. Revolutions. 2 1 2 2 2 2 73-0205 72-8350 72-4551 57-8380 54-7570 53-9564 53-1243 2 I 1 2 2 2 45-2945 45-2203 27-4096 27-2920 11-8572 11-5612 8244 0404 -58-62 1994 ,3642 0393 41'02 0484 42-01 8032 0482 -30'10 9427 0271 31-19 ! ; Weighted mt An -38'20 - 24 Va... - -11 Curv Radial v< 9 AQUIL^E 1731. 1908. July 26. Ol G. M. T. 18 h 07 m M ature . . . . .28 "locity -SR- )served by 1 w v w eaaured by / ' L- HARPEH> Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings. Settings. Revolutions. Settings. Settings. Revolutions. 2 57-8287 li 45-1997 1980 0407 42 49 i 57 7975 7982 0286 -41-50 27-3970 3792 0334 29 00 2 54-7409 2 27-2644 2 53-9365 9368 0330 38-00 * 11-8173 7869 0645 -48 31 2 53-1122 2 11-5376 2 45-2753 ' Weighted mean -39 83 V 24 Vtf n Curvature. , - '28 Radial velocity - 40 5 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a AQUILJE 1732. 391 1908. July 27. Observed by J. S. PLASKETT. (T. M. T. 18 h 15 Measured by W. E. HABPEB. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 I 2 2 <> 2 57-6860 57 6422 54-5924 53-7915 52-9636 45 1239 1 2 H 45 0540 29-4545 29-4224 11-6850 11-3507 2035 0352 36 75 7856 0412 -49 60 56C8 8415 0321 0099 28-47 - 7'41 9405 0293 33 72 Weighted mear Vn i -J ,2-23 73 12 28 V<* Curvat ire Radial velocity - 33 4 1733. 1908. July 27. G. M. T. 20 h 10 Observed by T. H. PARKER. Measured by W. E. HARPER. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. i Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 2 2 57-8173 57 ' 7872 54-7239 1 2 53-9094 53 1007 9241 0457 -52-60 7993 0273 -32-87 Weighted mea V* ... n 59-45 73 24 28 V, Curvat Radial velocity AQUIL^E 1735. 1908. Julv 28. Ol c>. M. T. 17 h 49 m y\ ure _ i M)-7 RPER. werved by j w E R easured by J Wt. Mean of Settings. Corrected Star Settings. Displace ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocit y 2 1 2 2 2 2 1 57-7810 57-7302 54 6993 53-8959 53-0681 45-2233 45 "1554 06'4 Observed by J. S. PLASKETT. Measured by T. H. PARKER. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings. Settings. Revolutions. Settings. Settings. Revolutions. 2 73 ' 0445 2 37-9735 * 72-9019 8689 0041 + 5'94 37-8169 8026 0479 46-17 2 72-4763 i 30-9439 9214 0458 . 41 12 2 54-7639 2 30-8932 1 54-0333 0153 0455 52-37 1 27-4672 4477 0351 30 46 2 54-0467 2 27-2659 2 53 1283 1 11-9221 9161 0647 + 48-46 2 45'2915 2 11-5123 1J 45-2840 2661 0274 28-60 Weighted mean +39'69 V a - 4-91 V d + '09 Curvature - '28 Radial velocity +34'6 394 DEPARTMENT OF THE INTERIOR 1908. Ausr. 5. G. M. T. 16 h 29'" .^ 1766. 9-10 EDWARD VII., A. 1910 Observed by .T. S. PLASKETT. Measured by W. E. HARPER. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings. Settings. Revolutions. Settings. Settings. Revolutions. 2 54 '7555 2 37 96% H 54 0175 0058 0360 + 41-44 1 37-8146 8042 0495 47 72 2 53-1220 2 11-9212 9096 0582 + 43 59 2 45 -2833 2 H'5188 H 45-2691 2594 0207 21-61 Cur Radial 6 AQUIL.E 176' 1908. Aug. 5. G. M. T. 17 h 18 m - 4 91 02 - '28 vature velocity 4 33 >KETT. LRPER. r. Observed by .T. S. PLAJ Measured by W. E. H.' Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 1 2 2 2 2 54'7< ; 50 54 0152 53-1277 45 2725 45 2916 37-9791 . 1 2" 37-7837 27-4480 27-2720 H-9180 11 5284 7738 4226 0191 0100 W98 S 68 9958 0260 + 29 93 2545 0158 16-50 8968 0454 + 34 00 Weighted Cur Radial 6 AQUIL^E 176$ 1908. Aug. 5. G. M. T. 18M8 m mean _!. 21 19 - 4'91 09 - -28 vature velocity 4 15'9 KETT. RPER. >. Observed by ,T. S. PLA? Measured by W. E. HJ Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity Settings. Settings. Revolutions. Settings. Settings. Revolutions. 2 73 0800 2 54-0263 9743 0045 - 5-18 i 72-f3io '8618 '0030 4 35 2 53-1625 o- 72'5112 2 45-3224 2 54-7953 1 45-2968 2476 0089 - 9-29 Weighted mean + 5' 00 Vd Curvature Radial velocity. . 4-91 19 28 04 REPORT OF THE CHIEF ASTRONOMER 395 SESSIONAL PAPER No. 25a 1908, Aug. 7. G. M. T. 17 h AQUIL^E 1776. Observed by T. H. PARKER. Measured by W. E. HARPER. Mean We. of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. ! 2 73 '0105 2 53-1270 i 72 '8287 '8311 0337 -48-90 2 45-2947 >" 72 4393 1 45-2207 1994 0393 41 '03 2 54 '7527 2 11-8727 8100 0414 -30-64 li 53 9542 9413 "0285 32'80 2 11-5703 Weighted mean -35'19 V a - 5-87 V d - -08 Curvature - '28 Radial velocity. -414 1908. Aug. 7. G. M. T. 17'' 45" B AQUTL^E 1777. Observed by T. H. PARKER. Measured by W. E. HARPER. j Mean Wt. of Settings-. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Velocity. Revolutions. 2 73 0173 . 2 45-3157 \ 72-8345 2" 72-4482 8281 0367 -53-25 1 45-2536 27-4414 2117 3756 0270 28-19 '0370 32 '12 2 57'8521 2 27 '3125 1 57--82S7 2 54 '7686 8028 0240 28'90 9. 11-9090 11-5960 8208 0306 22'64 H 53-9666 2" 53 1442 9371 0327 37 64 1 2 29-8450 29-6558 788i '0428 -38-05 Weighted mean - 32 57 V a - 5-87 Vj -14 Curvature - '28 1908. Aug. 17. G. M. T. 18 h 18 Radial velocity -389 6 AQUIL.^ 1789. Observed by) ,,' ^ rr Measured byJ^- KHAKPER - j Mean Corrected Wt. of Star Settings. Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 1J 57-8885 '8148 0120 - 13 81 2 45-3395 2 579031 1 45-2972 2313 007i 7 "72 2 54-8125 .....*. . . 2 38-0187 54-0320 '9614 2 531826 ' 0084 9 67 1 37-8079 '7484 0063 - 6 07 Weighted mean - 9'78 V a -10 39 V d - -21 Curvature - 28 Radial velocity -20'7 396 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 9 AQUILJE 1789. 1908. Aug. 17. Observed by \ w v WAT , PF . n G. M. T. 18>> 18" Measured by/ W ' K HARPER - \Vt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 1 2 2 57-8769 57-8580 54-7899 54-0078 53-1557 45-3130 1 2 1 4 2 1 45-2667 37-9966 37-7900 29-8666 29-6395 2271 0116 12-11 8105 0163 -20-15 7526 8260 0021 0049 2-02 - 4-36 9618 0080 9-21 | 1 Weigh ted mean 9 91 10-39 21 28 V a . . v d ... ---. - Curvatur e. . * Inadvertently remeasured. Radial velocity -20'8 6 AQUIL^E 1794*. 1908. Aug. 19. Observed byK y F HARPER G. M. T. 16 h 45 m Measured by j vv< *" a Wt. Mean of Settings . Corrected Star Settings . Displace- ment in Revolutions. Velocity. Wt. Mean of Settings . Corrected Star Settings . Displace- ment in Revolutions. Velocity. 2 ,' 2 1 \ 111-6998 111-3210 110-2983 71-8920 71-8568 69-5153 2 2 4 2 2 i 68-7143 63 3902 61-2072 60-3880 36-0921 35-9450 1330 0193 -11-19 2159 0286 11-75 8664 5373 0392 0155 17-29 6'73 9631 0427 -14-90 Weighted mean V,, ... -] [2-41 1 21 12 28 -1 Vrf Curvatur Radial veloci e. ...... tv. . -24-0 Plate made with three-prism spectrograph. I REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 397 1908. Aug. 20. G. M. T. 15 h 15" AQUIL^E 1799. Observed by") -.TT -n, TT.., Measured by }W. E. HARPER. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings . Corrected Star Settings . Displace- ment in Revolutions. Velocity. 9 72 '9899 2 45-2480 2644 0257 + 26'83 Jj 72'8610 8811 0163 + 23'65 2 37-9470 9" 72 ' 4241 1 37.7533 7655 0108 + 10-41 9 57 ' 8022 1 29-6165 6164 0175 + 15-56 1 57 ' 8005 '8387 0119 + 14-33 2 29.5990 2 54 7204 1 27-4145 4051 "0075 - 6 51 2 53 ' 9533 '9751 0053 + 6'11 ^ 27-2560 2 53 0898 ?i 11-8457 8229 '0185 -13'90 9 45 ' 2572 2 11 ' 5300 Weighted mean . ." + 12-45 -H'63 Vd "00 Curvature . . . - -28 Radial velocity. + 0'4 6 AQUIIJE 1800. 1908. Aug. 20. G. M. T. 15" 47 Observed by\, y F TT, RPFR Measured by/ VV ' * J> UARPKR - Mean Corrected Displace Mean Corrected Displace- Wt. of Star rnent in Velocity. Wt. of Star ment in Velocity. Settings . Settings. Revolutions. Settings . Settings. Revolutions. 2 73-0033 H 45-2531 2537 0150 +15'66 i 72-8582 8648 0000 o-oo 1 27-4586 4290 0164 + 14-23 2 72 4383 2 27 '2762 2 54 737o 2 11-9005 8700 0186 + 13 93 1 53-9710 9747 0049 4 5 64 1 59-8045 2 53 1090 1 59 ' 6690 6736 '0009 - 1 23 45 2729 Weighted mean +10'00 V -11-63 Vd - '05 Curvature ... - " 28 Radial velocity. - 20 398 1908. Aug. 20. G. M. T. 16 h 42" DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 Observed by) ^7- v TT Measured by }W. E. HARPER. 1801. Mean Coirected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity Settings . Settings. Revolutions. Settings . Settings . Revolutions. 2 54 7354 1 29 '6294 6194 0205 18'24 2 53-9787 9881 0183 + 21-06 2 29-6095 2 53-0997 1 27-4557 4361 '0235 20 31) 2 45-2665 2 27-2662 U 45-2453 2524 0137 14-30 * 11-8902 8614 0100 + 7 4! 2 29-9322 2 11-5362 1 29-8670 8575 0266 23-67 Weighted mean V a -11-63 Vd - 12 Curvature ... - "28 -18-52 Radial velocity . 6T) 1908. Aug. 21. G. M. T. 13 h 57 m AQUIL^E 1807. Observed by J. B. CANNON. Measured by W. E. HARPER. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity 2 2* 2 $ 2 73-0196 72-9000 72-4635 54-7685 54-0400 53-1406 45-3058 1 2 1 ?i 2 2 * 45-3011 29 6480 29 9315 27 4940 27-3002 11 9607 11-5717 2689 0302 31-52 8880 0232 j +33-66 8830 4406 0521 0280 46 32 24 30 0124 0426 49 03 8964 0410 ^30-71 Weighted a V< Cur mean " 4- 41 42 -12-04 11 - -28 r ature . . . Radial velocity + 28-7 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 399 1908. Aug. 21. G. M. T. 14 1 ' 32"' 9 AQUILJE 1808. Observed by J. B. CAXXOX. Measured by W. E. HARPKR. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings. Settings. Revolutions. Settings. Settings. Revolutions. 2 72 9966 2 45-2823 i 72-8700 8818 0170 + 24 67 1 45-2779 2692 0305 . 31-84 o 72 4343 2 37-9791 ji 57-8783 8783 "0515 62-00 1 37-8077 7978 0431 41-55 2 57 ' 8294 i 27-4542 4226 0100 8-68 2 54 ' 7475 * 27 '2782 H 54-0150 0110 0412 47-42 11 9453 9014 0500 + 37-45 2 53 1145 2 11 5512 Weighted mean +38'27 V a -12-04 V d + '06 Curvature - '28 Radial velocity. . . + 26 ' 1908. Aug. 21. G. M. T. 15 h 28'" AQUIL. 1810. Observed by J. B. CAXXON. Measured by W. E. HARPER. Wt. Mean Corrected Displace- Mea of Star ment in Velocity. Wt. of Setting.*. Settings. Revolutions. Settir 54 7201 2 29-5 53-9840 0054 0356 + 40-97 H 27'4 53-0910 2 27 2 45-2620 A 11-8 45-2523 2659 0272 28-40 2" 11-5 29 8745 8753 0414 39-47 Corrected Star Settings. 4459 8831 Displace ment in Velocity. Revolutions. 0333 0317 28-90 + 23-74 Weighted mean + 34 ' 73 V a -12-04 Vd - -02 Curvature - "28 Radial velocity r. + 22'4 25a 28 400 1908. Aug. 22. G. M. T. I5 h 29 m DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 Observed by 1 , 17 v TT Measured by} W. E. HARPER. 6 AQUIL^E 1811. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity, 2 2 * 2 2 2 72-9587 72-8387 72-3930 54-7138 53-9876 53-0885 2 1 1 2 2 2 45-2600 45-2775 27-4871 27-2762 11-9679 11-5587 8901 6253 +36-71 2911 4580 0524 0454 54-70 39 43 0134 0436 50-18 9170 0656 + 49-13 Weighted m V v d Cur ean.... -- + 47-86 -12-50 - -03 - '28 vature Radial velocity +35'0 1908. Aug. 22. G. M. T. 15 h 56 6 AQUIL^E 1812. Observed by \ w -,,, TT AT) Measured by jW.E. HARPER. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. .of Star ment in Velocity. Settings. Settings. Revolutions. Settings. Settings. Revolutions. 2 72 '9892 2 45'2531 72-8897 9116 0468 +67-91 1 45 2633 2838 0451 47 '08 2 72'4190 3 27-5378 '4728 0602 5^ '25 2 54 7430 2 27-3121 1 54-0200 6182 0484 55-71 2 12-0073 9163 0649 + 48-61 2 53 '1145 2 11 '5988 .. Weighted mean +52'03 V a -12-50 Vd - 08 Curvature. . . - ' 28 Radial velocity +39'1 REPORT OF TEE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 401 1908. Aug. 22. G. M. T. 16 h 21" AQUIL^E 1813. Observed by \ w TT. Measured by / W ' K HARPER - Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings. Settings. Revolutions. Settings. Settings. Revolutions. 2 72-9817 2 45-2804 4 72'8487 8779 0131 + 19-01 1 45 2807 2739 0352 36-75 2 72 4145 i 29 7215 6886 0897 79-74 i 57 '8665 8839 0571 68'75 2 29'6318 2 57'8120 1 27-4825 4387 0221 19 18 2 54 7342 2 27-2904 1 54 0030 0118 0420 48-34 2* U'9879 92i8 0704 +52-73 2 53-1022 2 11 '5733 Weighted mean +47'73 V a -12-50 Vcity. 2 73-0206 3 45 '2872 1 2 72-8615 72-4667 8505 0143 -20-75 ? 45-2305 37-9830 2169 0218 22 76 2 57-8371 1 37-7598 "7360 '0187 18'03 1 2 57-8167 54 7477 8090 0178 21-43 1 2 27-4280 27'2862 3884 0232 20 14 2 2 53-9567 53-1254 9471 0227 26-13 ? 11-8689 11 5489 8272 0242 -18-12 Weighted mean -21'20 V a -13-40 Vd - '16 Curvature... - '28 Radial velocity .... - 35'0 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 403 1908. Atrg. 27. G. M. T. 14 h 02"' AQUIL&: 1835. Observed by I T R p Measured by / J - R CANNON. Mean Corrected 1 >isplace- Mean Corrected Displace- Wt. of Star inent in Velocity. Wt. of Star ment in Velocity. Settings. Settings. Revolutions. Settings. Settings. Revolutions. 1 73 0129 2 45-2808 72-8466 8451 0197 -28-58 H 45-2153 2081 0306 31-95 72-4418 i 27-3961 3662 '0536 45-42 2 54-7388 2 27-2768 1 53-9403 9413 0285 32-80 1 11-8524 8125 0389 -29-14 2 53 1131 2 11 5472 Weighted mean V a Vd Curvature -33 92 -14-56 06 - -28 Radial velocity - 48 8 1908. Sept. 3. G. M. T. l h 17" 1864. Observed by J. S. PLASKETT. Measured by W. E. HARPER. Wt. Mean of .Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Setting-?. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 73 0322 li 45 2772 2317 0070 7-33 1 72-8740 8526 0122 -17 73 91- 29-9972 2 72 4635 14 29-8930 '8174 0135 12'08 2 57 8686 r 29-6557 5860 0129 11 49 1 57-8351 '7959 0309 37 '26 ^ 29-6787 2 54 7801 i 27-4700 3816 0310 27 '03 2.1 54 '0005 9616 0082 9-46 2 27-3355 53-1516 14 11 9352 8254 0260 -19'58 2 45 3191 ? 11 6205 Weighted mean - 14 ' 96 V a -17-37 V d -16 Curvature - "28 Radial velocity -32'8 404 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 AQUIL^E 1864. 1908. Sept. 3. Observed by J. S. PLASKETT. G.-M. T. 16 h 17 m Measured by T. H. PARKER. -Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 t 2 i 2 I* 72-9854 72-8295 72-4198 57-8199 57-8027 54-7376 53-9573 53-1065 2 1* 1 1 2 45 2737 45-2348 29-8500 30-9097 29-6055 11-8883 11-5697 8541 0107 -15-52 2347 8107 0040 0202 4 16 17-80 8122 0172 20-?<) 5660 8258 0181 0256 16-05 -19-17 9618 0080 9-20 Wejgh ted nifan L5'34 17-37 16 28 V a Vd - Curvatur e Radial velocity - 33 1 Independent measurement. 6 AQUIL.E 1875. 1908. Sept. 8. Observed by J. S. PLASKETT. G. M. T. 12 h 42 Measured by T. H. PARKER. Wt. Mean of Settings . Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings . Corrected Star Settings . Displace- ment in Revolutions. Velocity. 1 ! 4 2 1 2 73-0022 72-8789 72-4437 54-7440 54-0395 53-1178 2 i 4 2 1 2 45 2770 45-3101 27-5014 27-2778 12-0038 11-5614 8850 0202 + 29-31 3067 4694 0680 OE68 70-99 49-34 0356 0658 75-73 9496 0982 + 73-55 Weigh ted mean 4-1 )7'85 0;) V a .. 17-08 + Yd Curvatur B - '28 Radial velocity. +50'6 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 6 AQUIL^E 1875*. 405 1908. Sept. 8. Observed by J. S. PLASKETT. G. M. T. 12 h 42 m Measured by W. E. HARPER. Wt. Mean of Settings . Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. I- 1 tO tO tO IO tO" 54-7676 54-0485 53-1396 45-3024 45 3295 2 i 1 2 29-6453 29-7430 12-0185 11-5840 0218 0520 + 59-85 6966 9417 0977 0903 86-66 +67-63 3007 0620 64-73 Weigt * Check measurement. R e AQUIL^: is; 1908. Sept. 8. G. M. T. 13 h 40 ited mean 4- i9'07 09 -17-08 Curv adial veloci '6. ature ty - '28 - 51-8 JKETT. RKER. Observed by J. S. PLAS Measured by T. H. PA Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings . Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 73-0136 U 45 3045 3014 0627 65'45 2 72-9175 72-4645 9105 0457 +66-31 1 2 27-5001 27-2761 4706 0580 50-34 2 54 '7428 H 11-9869 9574 1060 +79-39 H 54-0359 0350 0652 75-04 2 11-5444 2* 45-2767 Weighted mean +68'i V -17-08 Vd -00 Curvature - "28 I 1908. Sept. 11. G. M. T. 15 h Radial velocity +51"5 6 AQUIL^E 1878. Observed by J. B. CANNON. Measured by T. H. PARKER. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings . Settings. Revolutions. Settings. Settings. Revolutions. 73-0192 2 45 2692 * 72-8480 8396 0252 -36 -56 1 45-2233 2277 oiio 11-48 72-4503 1 27-3789 3712 0414 35-93 ?. 54-7399 2 27-2541 2 53-9497 9515 0183 21 -06 H 11-8400 8283 02;?i - 17 30 a 53 1104 2 11 5249 Weighted mean - 22'29 V rj -20 21 V d - -09 Curvature - '28 Radial velocity - 47 .7 406 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 191C a a o ^ 5? i > * 02 M 5 o < o _ &3 * O o a 3 O3oet-.CiO3eoogit-t < W5) O - o -- w^ 1 o i in 1-1 oc e; o fr-p w oo > e oo ec c >p ^< s t-TO t 10 rv CXC-nW^fflO -^.-55 IMCM ^ o ^ i- * i^ - w !-> w w o y. i- -. c; t- x 7-1 o n -i- -. --r t- -x r. -M -i r: .- .-. i- 1- t. REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 407 . . S"3 g.b 1 .J: ' s o o '* a = - ^5-(O 3fe ^ o c* ec o cs oo o co oo >H o o o eo to of Wave S-S 3-S * >> Settings. *i Length. s r sf S* s *v ^ Settings. Length. it II "*c 8 " w ^ ^ o ^5 Q 2 73'9685 4891-134 3 52-5955 4460 292 l 73 1420 4871-413 47-6274 4379-348 I 72 6821 4860-564 607 527 920 -56-76 2 45-0505 4339-626 714 634 920 -63-48 I 56 "5256 4528 '760 S 44 ' 1325 4325-827 i 53-8061 4480-945 985 400 415 -27 76 Weighted mean -5653 V a + 1-45 V d - -04 Curvature ... - ' 28 Radial velocity. 1907. May 31. G. M. T. 17 h 38" HERCULIS 801. Observed by J. S. PLASKETT. Measured by C. R. WESTLAND. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 73 0174 1 53'9504 9078 0620 71'36 2 72-8193 8105 0543 -78'79 2 53-1565 2 72-4559 2 45-2192 1557 0830 -86-65 2 54 ' 7825 2 45-3368 Weighted mean -80'45 V a - '68 Vd - -02 Curvature - .28 Radial velocity. -81-4 1907. June 8. G. M. T. 19 h 28 m HERCULIS 810. Observed by J. S. PLASKETT. Measured by C. R. WESTLAND. .. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 1 a 2 72-9982 72-8130 72-4367 54'7y31 3 2 2 1 53-9506 53-1734 45-3626 45-2450 8942 0756 -87-02 8281 0367 -53 25 1556 0831 -86-76 - Weigl ited mean J *0 21 3 00 19 28 V a - Vd - Curvature ... - Radial velocity - 83'7 410 DEPARTMENT OF THE INTERIOR f HERCULIS 81(i. 9-10 EDWARD VII., A. 19 1907. June 10. Observed by J. S. PLASKETT. G. M. T. 17 h 47 ra Measured by W. E. HARPER. , . . e Mean Computed 1 01 1 1 B Mean Computed | B > B of Wave -2^" _ ^> of Wave J^ _ g >= Settings. Length. c? | * "a, 8 Settings. Length. If 3-& - c j +- I- 0> o s E 3J o So" T ^ Q 25 G > ^ O fc Q > 73-3707 4875-671 1^ 53-2681 4470-617 11 72 '9235 4865 ' 085 2 452728 4341-820 72-7904 4861-951 807 527 320 + 19 74 2 45-2356 4341-256 594 634 040 2-7 2 54-3881 4489-915 i 27-4999 ! 4102 238 KM; '890 216 -156 1 53-9850 4482 931 150 400 750 + 50-17 3 27-3170 4100-053 Weighted mean. ic,-04 ... - 3-57 Vd 07 Curvature.. . . ... - '28 Radial velocity . . + 12 .- HERCULIS 827. 1907. June 11. Observed by l w H , RPKR G. M. T. 15 h 39'" Measured by / Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Vel'xntr Revolutions. 2 1 2 2 72-9503 72 8122 72-3825 54-0317 i-ICOH* 54-0175 45-3037 45-2540 0116 0448 -51-5 8724 0076 + 11-02 2237 OUiO 15 ; Weigh Rs e HERCULIS 83 1907. June 12. G. M. T. 18 h 35"' ted mean +* Jl-90 f 07 V a -386 Va --- Curvatur idial veloci 8. e . . - '28 ty. . . 1 7-8 KETT. LRPEH. Observed by J. S. PLAS Measured by W. E. H. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocit; 2 ? 2 i 72-9986 72-8160 72-4380 54-0675 53-9500 f 45-2585 45-3356 27-4375 27-3726 1957 0430 44'j 8258 0390 -56 59 3116 1010 -87'{ 9113 0585 67-33 Weighted mean -5493 V a - 4-15 W - -14 Curvature . . - '28 Radial velocity -59'5 REPORT OF THE CHIEF ASTRONOMER 411 SESSIONAL PAPER NO. 25a 6 HERCULIS 838. 1907. June 12. Observed by J. S. PI.ASKKIT. G. M. T. 18 h 35 m Measured by T. H. PARKER. Mean Wt. of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolution?. Velocity. 1 72-9608 1 72 7742 H 72-3915 2' 45 2982 1 2 2 45-2100 43-5655 27-4011 27 33 3 1853 0534 55-74 7756 -0392 -56-87 3175 0951 -82-54 Weigb ted mean . . 51-55 4-15 14 28 V a Curvatur e The iiiean of the two measurements, 61' 7 used. Radial velocity - 66' 1 1907. June 13. O. M. T. IS 1 ' 25' e HERCULIS 847. Observed by W. E. HARPER. Measured by C. R. WESTLAND. Mean Wt. ^ of Setting's. Corrected Displace- Star ment in Settings. Revolutions, 54-7738 53 9268 53-1442 8948 0750 Velocity. Wt. ; i -86-32 Mean of Settings. Corrected 1 Displace 45 3226 45-1962 Star Settings. ment in Revolutions. Velocity. 1472 '0915 -95'52 Weighted mean Vrf Curvature -90-87 - 4 43 - -16 - '28 Radial velocity - 95 7 l'07. June 13. G. M. T. !* 25'" e HERCULIS 847. Observed by W. E. HARPER. Measured by T. H. PARKER. Mean Wt of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Mean Wt. of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 72 9662 i 72-7752 1 72-4080 1 54-0198 1 .-3-8890 1 52 2373 2 48-7615 .', 45-2105 1 45-2774 8186 0462 -67 03 2068 0319 -33-30 8990 0708 -81-48 Mean of two measurements, -83 '2 used. Weighted mean 55-82 4 43 16 28 V a Curvatur Radial veloci e tv ro-r 412 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 19K e HERCULIS 851. 1907. June 14. Observed by J. S. PLASKETT. G. M. T. 17 h 43 m Measured by W. E. HARPER. a> "c Mean Measured i . S Mean Measured f S of Settings. Wave Length. ni fij "H. 00 Velocity. of Settings. Wave Length. if j H 00 Velocity ? fc Q '& fc Q ? 73-3997 4875-675 H 53 9475 4482 '744 '400 344 + 23'74 72-9468 4864-956 ? 45-2453 4341-337 1* 72-8165 4861-887 .527 360 + 22 21 H 45 2036 4340-534 634 100 - 6'9C 1 72-3854 4851-790 1 27'4152 4101-900 890 010 + 0"7J 1 53-9856 4482-656 9, 27-2529 4099-650 i Weighted mean + 9 ' 64 Vo - 4'72 Vd - '09 Curvature ... - " 28 Radial velocity 4'5 e HERCULIS 851. 1907. June 14. Observed by J. S. PLASKETT. G. M. T. 17 h 43 m Measured by T. H. PARKER. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocit; 1 1 73-0227 72-8756 72-4630 54-7568 54-0085 1 2 2 53-1210 45-2536 45-3006 27-2977 27-4617 8898 0250 +36-27 2267 0120 -12'ffi' 9991 0293 +33-72 1108 0018 - 1-5(1 Weigh ted mean + 17-76 V a - 4 72 - -09 - '28 Curvature The mean of two measurements, + 7 ' used. Radial velocity + 12 ' 7 HERCULIS 862. 1907. June 20, Observed by W. E. HARPER. G. M. T. 16 h 37 m Measured by J. N. TRIBBLE. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocit; i 4 1 2 i 72-9908 72-4301 72-8461 54-7464 53 9312 2 2 1 2 i 53-1120 45 2676 45-1917 27 2746 27-3742 8644 0004 - 0-29 1977 0410 -42'7! 9290 0408 -46-96 3462 0764 -57'? Weighted mean V,, 51-26 6 33 07 28 _ Vd . - Curvatur e Radial velocity -37 "9 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 413 1907. June 20. G. M. T. 16 h 37 m 6 HERCUTJS 862. Observed by W. E. HARPER. Measured by T. H. PARKER. Wt. Mean of Setting8. ( Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean Qf Settings. Corrected Star Settings. Displace- ment in Revolutions Velocity. 1 73-01C6 1 45-2182 1950 0437 45'62 1 72-8604 8527 0121 -17 55 2 43 5599 2 72'4557 1 27-4358 3833 0293 -25'43 o 45-2969 2 27'2991 Mean of measurements, 34 '5 used. Weighted mean - 27'53 V a - 6 33 V d - -07 Curvature. . . - ' 28 Radial velocity -34'2 1907. June 21. G. M. T. 18 h 10" HERCULIS 871. Observed by J. S. PLASKETT. Measured by J. N. TRIBBLE. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. H 72-9582 U 45-1420 1655 0732 7639 i 2 72 3957 li 27-2546 , 1* 72-7847 45 ' 2501 8357 0291 -42-22 i 27-3658 3578 0641 -55-63 * Weighted mean -58'78 V a - 6'49 Va- - -19 Curvature... - '28 Radial velocity. -65'7 1907 June 25. G. M. T. 16 04- e HERCULIS 881. Observed by \ w v Tr. npim Measured by f W * K HARPEB - Wt. Mean of Settings. 49-4200 45-2146 44-2931 Corrected Displace- Star ment in Velocity. Wt. Settings. Revolutions. . 'If 75 0612 -63-89 1 - Mean of Settings. 27-3185 27-2462 Corrected Star Settings. 3189 Displace- ment in Revolutions. 1030 Velocity. -40 Weighted mean -72'40 V a - 7 64 V d - -04 Curvature - "28 Radial velocity -80'4 414 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 6 HKRCULIS 893. 1907. June 27. Observed by W. E. HARPKH. G. M. T. 16 h 32'" Measured by J. N. TRIBBLE. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Mean Wt. of Settings. Corrected Star Settings. Displace- ment in Revolutions. Veloci ty. 2 I 2 73 2721 72-9900 72-8555 54-0335 1 53-9786 2 45-2810 i 45-2918 9741 0043 4-95 8745 -0097 +14'07 2843 0456 + 47-59 Weighted mean 12-64 V a - 8'22 11 - '28 Vrf .. Curvature Radial veloci e HERCULIS 913. 1907. July 4. G. M. T. 'I6 h 18 m ty 4 4-0 lU'KR. BBLE. Observed by W. K. HA Measured by J. N. TK Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. ] Mean Wt. of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. ! 2 2 54 0216 53-9485 2 45-2683 9557 0141 -16-22 Weighted mean _- 16-22 9-98 14 28 |j| 26 6 _ Va" _ Curvatur Radial veloci e _ tv. . e HKRCULIS 020. 1907. July 8. Observed by J. S. PI.ASKETT. G. M. T. 16 h Measured by J. N. TRIBBLE. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. 1 Velocity. 1 Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity - 2 2 u H 72-9265 72-3632 72 7804 53-9754 53-9156 2 1 2 45-2319 45-1886 27-2471 27 4015 2403 OOS4 8-79 8172 0015 - 2 17 4763 0202 -17 60 9056 0010 - 1 15 Weigh RJ ted mean 6 12 10-92 14 28 V a - 1 Curvatur idial veloci e by. . -17'5 REPORT OF THE CHIEF ASTRONOMER 415 SESSIONAL PAPER No. 25a e HERCULIS 928. 1907. July 9. Observed by\ T vr T G. M. T. 14 h 32'" Measured by/ J - * * Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. li 2 2 54-0232 54 0319 45-2815 1 li 45-2855 30-9135 29-6773 2775 0388 49-90 0375 0677 +77-91 6342 0501 + 44-42 Weigh Hi e HERCULIS 92! 1907. July 9. G. M. T. 14 h 32 m ted mean . -- + ' )3'31 V a ... -11-26 - 11 - '28 Vd Curvatui- idial veloci J.* B ... ;v. +' U-6 BLE. RPER. Observed by J. N. TRIB Measured by W. E. HA Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity Settings. Settings. Revolutions. Settings. Settings. Revolutions. 2 72-9585 2 53-9874 U 72-8250 8764 0116 + 16-83 * 53-9415 9829 0131 + 15-08 72-3931 2 45'2441 4 57-8595 8969 0700 [+ 84-28] H 45-2136 2431 0044 + 3-82 i 57 '7826 2 29-6396 6406 0417 +37-00 i 57-6674 7048 1220 [-i44 -48] 2 29-5979 Weighted mean +20"60 V a -11-26 Vd - -11 Curvature... - '28 * This result used. Radial velocity + 9'0 1907. July 10. G. M. T. 14 h 55" e HERCULtS 937. Observed by J. S. PLASKETT. Measured by J. N. TRIBBLE. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 1 72-9735 1 45 '2284 '2288 '0199 -20'83 1 72-8361 261 0054 + 7'84 2 27-2965 V 45'2S32 A 27 ' 4291 '4545 '0420 -36'60 Weighted mean -20'86 V a -11-49 Vd -09 Curvature - "28 25a 29 Radial velocity. -32 7 416 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 1907. July 10. G. M. T. 14" 55 m e HERCULIS 937- Observed by J. S. PLASKKTT. Measured by W. E. HARPER. Mean Corrected Displace- Mnan Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings Settings. Revolutions. Settings. Settings. Revolutions. 1 54 6678 2 45-2191 1 53-8654 9382 0316 -36 37 1 45-1485 2100 0287 -29-96 1 53'0405 Mean of measurements, 39'0 used. Weighted mean - 33' 16 V a -11-49 Vd - '09 Curvature . . - ' 28 Radial velocity -45'0 1907. July 18. G. M. T. 16 h 10 m e HERCULIS 952. Observed by W. E. HARPER. Measured by J. N. TRIBBLK. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings. Settings. Revolutions. Settings. Settings. Revolutions. 2 72 '9883 | 53-9283 9333 0365 42 01 2 72 ' 4271 2 45 2698 1 72-8008 8208 0440 -63-85 1 45-2109 2i47 0240 -25-05 2 54-0238 Weighted mean. -43 96 V a -13-18 Vtf - '19 Curvature . . "28 Radial velocity - 57'6 1907. July 20. G. M. T. 16 h 39 m HERCULIS 957. Observed by J. S. PLASKETT. Measured by J. N. TRIBBLE. - Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocitj Settings. Settings. Revolutions. Settings. Settings. Revolutions. 2 72-9599 2 45-2827 2 72 '3852 1 45-2473 2482 0000 OC 79 SOA^ '8315 '0128 + 18 ' 34 2 27'3141 2 54-0154 | 27-5080 5158 0193 + 16-85 1 53 9642 9642 0076 + 8'77 Weighted mean +10'15 V a -13-57 Vd - -19 Curvature '28 Radial velocity. - 3-9 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a e HERCULIS 976. 417 1907. Aug. 1. Observed by 1 T vr TRTRRI R G. M. T. 17 h 20" 1 Measured by / J ' Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 i 2 2 73-0008 72-8353 54-0320 53 9627 2 1 2 i 45-2806 45-2454 27-2821 27*4465 8443 0205 -29 74 2384 0003 00 9595 0103 11-85 4110 0109 - Jl-46 Weighted mean V,, .... 0-79 L5 51 27 28 Radia e HERCULIS 9 1907. Aug. 3. G. M. T. 13 h 28 ra V<* . . - Curvatui 1 velocity 26'8 TT. [AKPEK. 79.* Observed by J. S. PLASKB Measured by TRIBBLK & I Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 9 72-9868 & 27-4924 4509 0290 + 25'17 1 72-8703 S953 0305 + 44-26 2 54-7430 2 54-0237 f54O280 O278 "0620 + 71-36 2 2 54-0309 54 ' 7369 0360 0662 +76-19 C'ntre { 53-9537 '9535 O163 red. + 18'76 2 45-2775 | 53-8760 8758 0940 -108-19 1 j 45-2820 27 '2883 2780 0393 + 41-08 2 53 1113 violet. *Plate not used in the results. " f HERCULIS 987. 1907. Aug. 6. Observed by \ T vr T . G. M. T. 17" 35'" Measured by / Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 72-6897 2 44-9542 1 * 72-5573 *843 0122 + 17'75 1 44-9849 2833 0244 + 25 63 Weighted mean ..................... +22 '96 V a .............. -16-16 Curvature.. . Radial velocity "28 + 62 25a 418 DEPARTMENT OF THE INTERIOR 1907. Aug. 22. G. M. T. 10 h ,49 e HERCULIS 1018. 9-10 EDWARD VII., A. 1910 Observed by W. E. HARPER. Measured by J. N. TRIBBLE. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 54-0698 2 45-2977 1 54-0566 0156 0458 +52-71 * 45-3014 2774 0387 + 403* Weighted mean +48'60 V a -17-45 Vd - -27 Curvature - '28 Radial velocity. + 30-6 1907. Sept. 20. G. M. T. 14 h 37" e HERCULIS 1062. Observed by W. E. HARPER. Measured by J. X. TRIBBLE. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocit; Settings. Settings. Revolutions. Settings. Settings. Revolutions. 2 54 '0379 2 45 2630 1 53-9738 9647 0051 - 5-86 1 45 2412 2512 (.125 -13.0, Weighted mean + 3 ' 59 a Vd Curvature . . . Radial velocity. - 5'90 - -28 - "28 - 2-9 1908. March 9. G. M. T. 20 h 50"' e HERCULIS 1391. Observed by 1 Measured by / w . ., HARPKB. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Veiocit 2 54 7533 1 27 3570 3650 0566 49 '1 2 53 '9358 '9253 0445 -51'22 2 27 "2385 2 53 1215 1 11 7667 7897 0617 -46-2 2 45 -2735 f H'4840 1 45-2060 2061 0326 34 03 Weighted mean - 46 ' 03 V a + 17-5*. . V d * -14 Curvature.. - .28 Radial velocity - 28 6 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a e HERCULLS 1403. 41 1908. March 16. Observed by \ w v . G. M. T. 21 h 42- Measured by/ W ' R HARPER - Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 12 3 2 ^ 54-7088 53-8238 53 0835 45-2754 45-1363 27-4961 1 1 2 2 4 27-4090 27 3376 27-3180 11-8287 11-6327 3380 2666 0746 1460 E-64'75]f - 126-73J 8561 1137 -129-87 7037 1477 - 110 63 1345 4251 1042 0125 -108-78 [+10-85]* Weighted mean 4 Vn lines 1 17-66 28 + 16-96 + -05 Vd ......... Curvature . . . Red. f Centre. Violet. Radial velocity - 100 9 1908. April 13. G. M. T. 21 h 35 m e HERCULIS 1483. Observed by\ w Measured by/ W ' * Mean Corrected Displace- Mean Corrected Displace- Wt. of Settings. Star Settings. ment in Revolutions. Velocity. Wt. of Settings. Star Settings. ment in Revolutions. Velocity. 1 55-0591 0413 0839 - 97-83 A 45-2031 1830 0557 -58-15 ?, 54 7597 2 73-0290 3 53-8897 8728 0970 -111-65 2 66-3185 2998 1119 + 145-09 V 53-1281 1 41-4857 '4625 1653 + 165 30 7 45 2936 9 41 3097 Weighted mean neg. lines - 102 '63 V a +12-31 Vd - -09 Curvature... - "28 Radial velocity - 90-7 420 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 e MEKCUL1IS 1494. 1908. April 15. Observed by J. S. PLASKETT. G. M. T. 20 h 40 Measured by W. E. HARPER. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity 2 1 2 2 54-7571 54-0087 53-1325 45-3117 45-2995 !> 27-5470 27-3528 12-0567 11-6701 4416 0290 25-17 9910 0212 + 24-40 8947 0433 + 32 43 2614 0227 23-70 Weigl Ra e HERCULIS 15 1908. April 22. G. M. T. 20 h 33 ra ited mean + 26-75 11-87 V a + 04 -- -28 Curvature dial velocit 11. ,, 38-3 KETT. RPER. Observed by J. S. PLAS Measured by W. E. HA Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 1 2 -2 H 54-7537 53-9496 53-1311 45-2841 45-2051 I" 1 2 27-4398 27-3292 11-9322 11-6453 3576 0550 47-74 , 9343 0355 -40-86 - '7951 '0557 -41-72 ; 1947 0440 45-93 Weigl Ra ited mean 44-61 05 28 V a *. . + 10-16 Curvature _ dial velocity... - 34 8 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 421 1908. April 22. (i. M. T. 20 h 53'" Measured by W. E. HARPER. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions, Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 H I' 54-7390 53 9468 53 1052 1 2 45-1900 45 2802 1834 0553 -57 73 9515 0183 -21-06 Weighted mean . V. i (5'73 4-39 14 28 _ Vd - Curvatur B. . . . * Check measurement. Radial velocity - 40'5 e HERCULIS 1625. 1908. June 22. Observed by J. S. PLASKETT. G. M. T. 17 h 27 m Measured by W. E. HARPER. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity, j Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 9 1 54-7181 53 9437 53 0867 45 2605 45-2005 I* 27-4445 27-2660 11-8797 11-5367 4251 0125 + 10-85 9684 0014 - 1-91 8502 0012 - 0-90 2137 0250 -26-10 Weigh RJ ted mean ... .... 6-24 7-15 11 28 L3'8 V a Curvatur i-dial veloci e bv... 1908. June 24. G. M. T. 16 h 27'" HERCULIS 1630. Observed by J. S. PI.ASKETT. Measured by W. E. HARPER. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 2 1 1 73-0647 72 9033 72-5011 54 7925 53-9978 53-1602 to to to M to to KH 45-3237 45 2575 27-4458 27-3065 11-8987 11-5698 8481 0167 -24-23 2074 3860 0313 0266 32-68 23-09 484 0214 24-63 8362 0152 -11-38 Weigl Ra ited mean . . . . 23-00 7-68 04 28 V a ... V d - Curvature dial velocit y 31-0 426 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 1908. June 26. G. M. T. 16 h 46 m e HERCULIS 1640. Observed by) w F H . RPFR Measured by/ w< *" MARPER - Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings. Settings. Revolutions. Settings. Settings. Revolutions. 2 54 '7353 2 53'1042 1 53-9739 9826 0128 + 14 73 V a Curvature. Radial velocity. . + 14 73 6-1 HERCULIS 1648. 1908. June 27. Observed by J. S. PLASKETT. G. M. T. 17'- 07 m Measured by J. B. CANNON. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings. Settings. Revolutions. Settings. Settings. Revolutions. 2 54-6613 2 27 3914 '4389 0266 22-06 14 53-9578 0373 0675 + 77'80 3 27 "2075 2* 53 0325 1 11-8777 9092 0578 + 43-29 2 45-2056 3 H'4693 11 45-1725 2405 0018 1-88 Weighted mean + 34 49 V a 8-47 Vd '11 Curvature . . - ' 28 Radial velocity . 25-6 6 HERCULIS 1048.* 1908. June 27. Observed by J. S. PLASKKTT. G. M. T. 17 h 07 ra Measured by J. B. CANNON. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 1 2 2 73 0323 72-9046 72-4869 54-7837 54-0660 53-1513 2 14 1| 3 45-3181 45-2971 27-5276 27-3309 12-0159 11-5935 8746 0098 -r!4'22 2531 4536 0144 0410 15 05 35 59 0260 0562 64-69 9229 0715 + 53 63 Weigl ited mean + 42-15 V a 8'47 11 29 Curvature * Check measurement. Radial velocity + 29'4 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 427 1908. June 27. G. M. T. 17 h 07 r t HERCULIS 1648.* Observed by J. S. PLASKETT. Measured by W. E. HARPEK. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 5i'7470 i 27-4466 4322 0196 17'01 ! 54 '0110 '0063 "0365 + 42'0i 2 27-2610 ?, 53 1164 1 11-9287 9037 0523 + 39-17 9 45-2902 2 11 5322 H 45-2737 2571 0184 19-21 Weighted mean +29'62 V a - 8-47 Vd - '11 Curvature . . - '28 h Check measurement. 1908. July 1. G. M. T. 16 h 15 m Radial velocity + 20'8 HERCULIS 1653. Observed by J. S. PLASKETT. Measured by J. B. CANNON. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings. Settings. Revolutions. Settings. Settings. Revolutions. 2 54 '7746 1 27 '5156 4756 0630 54'68 2 54-0547 0247 '0549 + 63 19 3 27 2893 2 53-1395 U 11-9291 8871 0357 + 26 76 2 45-3045 3 11 5478 1 45-2795 2490 0103 10 75 Weighted mean +42 17 V a - 9-48 Va- - -11 Curvature . . - ' 28 Radial velocity +33'3 1908. July 1. G. M. T. 16 h 15 e HERCULIS 1653.* Observed by J. S. PLASKETT. Measured by W. E. HARPER. :\vt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 54 7392 . 27-4403 4400 0274 23-78 1 53-9887 '9943 0245 + 28-20 1 27-2470 1 53-1035 1 11-8804 8856 0342 + 25-61 2 45-2625 2 11-5020 45-2276 2387- 0000 oo Weighted mean . . . V a - 9-48 Vd - -06 Curvature '28 + 21-90 * Check measurement. Radial velocity +12' 1 428 DEPAPTME\T OF THE INTERIOR 9-10 EDWARD VII., A. 1910 1908. July 1. G. M. T. 16 h 15 HERCULIS 1653. Observed by J. S. PLASKETT. Measured by W. E. HARPER. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt, Mean of Settings. Corrected Star Settings. , Displace- in tnt in Revolutions. Velocity. 2 1 2 2 54-8447 53-0962 53 2062 45-3688 4 2 45-3489 11 9904 11 6090 2537 8880 0150 0366 15 66 + 27-41 9977 0279 + 32 11 Weighted meat i +< >6'94 - 9-48 11 - -28 Vrf Curvat ure Check measurement. 1908. July 3. G. M. T. 19 h 40 m Radial velocity + 17 ' 1 e HERCULIS 1661. Observed by T. H. PARKER. Measured by J. B. CANNON, Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity-} 2 24 2 54-7681 53-9294 53-1436 2 1 45-2998 45-2548 9004 0694 -79-88 2268 0119 -13 : 6j Weig E f HERCULIS 1( 1908. July 3. G. M. T. 19" 40 hted mean 49-53 9-97 26 28 V a Vd . . - Curvatu i-adial veluc re ity 60 RKER. [ARPER. Observed by T. H. PA Measured by W. E. H Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions Vrlodt 2 2 2 54 7214 53 8761 53-0911 2 1 45-2530 45 1670 8968 0730 -84-02 1877 0510 -, Weighted mean -75'62 V a - 9'97 Vd - -26 Curvature . "28 Check measurement. Radial velocity - 86 ' 1 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 429 1908. July 6. G. M. T. 17 h 35"> e HERCUL1S 1666. Observed by J. S. PLASKETT. Measured by J. B. CANNON. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity Settings. Settings. Revolutions. Settings. Settings. Revolutions. 54-7101 14 27 '3494 3934 0192 16-66 1 53-8800 9180 '0518 -59'62 ? 27 ' 1962 2 53-0710 i H'7754 '8284 0230 -17'23 > 45 '2333 2 11 4534 1-2 45 1985 2375 0012 1-25 Weighted mean - 20 74 V a -10-70 Vd - '06 Curvature - '28 Radial velocity - 31 ' 7 1908. July 6. G. M. T. 17 h 35" e HERCULIS 1666.' Observed by J. S. PLASKBTT. Measured by W. E. HARPER. Mean Corrected Displace- Mean Corrected Displace- .of Settings. Star Settings. ment in Revolutions. Velocity. Wt. of Settings. Star Settings. ment in Revolutions. Velocity. 57-8433 11 45-2230 2223 0164 -17'20 57-8432 8293 0025 + 3-01 27-3862 3874 0252 -21-87 54 7567 2 27 2454 53-9847 9752 0054 + 6-21 A 11-8301 8383 0131 - 9-81 53-1164 2 11 5190 45-2745 Wt. Weighted mean - 5'54 V a -10-70 Vd - '06 Curvature - "28 Radial velocity -16'6 430 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 1908. July 8. G. M. T. 15 h 47" e HERCULIS 1675. Observed by J. B. CANNON. Measured bv W. E. HARPER. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ' ment in Velocity. Settings. Settings. Revolutions. Settings. Settings. Revolutions. 2 73-0235 3 45 2741 1 72-8670 8534 0114 -ie'-M 1* 45-2271 2267 6120 -12-53 2 72-4584 27-4307 '4076 0050 - 4'34 2 54-7415 2 27 '2697 14 53-9786 9803 0105 + 12-08 1 11-8571 8288 0226 -16 93 l| 53-1090 2 11 5355 Weig Ra e HERCULIS 16 1908. July 8. G. M. T. 15 h 47 m tited mean ... 6'4l 11-15 07 28 V a .. . . Va- Curvature, dial velocii 75.* y 17-9 "ON. RPER. Observed by J. B. CANI Measured by W. E. HA Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity s 4 2 2 2 2 57-7785 57-7762 54-6950 53-9312 53-0617 45-2267 8317 0049 + 6-02 i 1 1 2 1 2 45-1881 30-8478 27-3860 27-2254 11-8146 11-4915 2350 0037 -.| "4072 0054 - 4-69 9798 0100 + 11-51 8303 0211 -15-80 Weigl Ra ited mean 04 11-15 07 28 V a Va- Curvature dial velocit v. . . - 11-5 ' Check measurement. REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 431 1908. July S. <;. M. T. 16 h 32" e HERCL'LIS 1676. Observed by\ T T> p. .,..., Measured by } J - RCAVNON - Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. I Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 54 ' 8885 1 27-5711 4031 0095 8' ^5 u 54'0948 "9498 0200 -23-02 2 27'4152 2" 53-2536 1 12-0378 8489 0025 - 1'87 n 45 4"M3 2i H'6959 1 45-3866 2356 0031 3-24 Weighted mean . V a V* Curvature . - 10-64 - 11-15 14 - -28 Radial velocity - 22'2 1908. July 9. G. M. T. 17 h 12" e HERCULIS 1682. Observed by"! -. 17 -p, TT Measured by }W. E. HARPER. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 73-0156 n 45-2675 2565 0178 + 18-58 i "2 ' 8768 8714 0066 - 9-57 2 41-2977 2" 72'44'.'0 i 27-4402 4102 0024 - 2 08 2 54-7490 2* 27 '2766 3 2 54-0263 53-1160 0207 0609. + 70 09 , 4 11-9452 H'5482 9044 0530 + 39 70 9 45 '2846 j Weighted mean + 42'97 V a - 11-36 Vd - "15 Curvature . - "28 Racial velocity + S1'2 432 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. f910 1908. July 10. G. M. T. 14 h 37'" e HERCULIS 1685. Observed by} T T> n AWHriw Measured by / J - B. CANNON. i Mean Corrected Displace- Mean Corrected Displace- IWt. of Star ment in Velocity. i Wt. of Star ment in Velocity. Settings. Settings. Revolutions. Settings. Settings. Revolutions. 2 54'7810 H 27-4458 3880 0246 21'35 2 53 '9982 9602 0096 -H'49 2 27-3042 2 53-1500 1| 11-8880 8260 0254 -19-02 2 15 '3197 2 H'5696 1 45-2720 2260 0127 13 26 Weighted mean V,, 16-13 11-58 oo 28 Vrf... Curvatur Radial veloci e HERCULIS 1686. 1908. July 10. G. M. T. 15* 34 e tv 27'9 NNON. Observed by) T T> /-<, Measured by)' Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. X Corrected Star Settings. Displace- ment in Revolutions. Velocity 2 2 1 54-7365 53-9496 53-1102 45-2762 45-2158 2 2 2 27-4528 27-2597 11-8304 11-5280 9535 0163 -18-76 8099 0415 -31-07 2146 0230 24-01 Weighted mean 24 56 11-58 06 28 _ Vrf... Curvatu Radial veloc e HERCULIS 1693. 1908. July 11. < G. M. T. "I6 h 58 m re itv 36-1 ETT. ON. Observed by J. S. PMSK Measured by J. B. CAN> Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity 1 1 1 2 2 2 73-0160 72-7961 54-7200 53-8695 53-0811 45-2396 2 1 2 45-1437 27-2885 27-2267 11-7051 11-4860 1197 2685 1198 1440 125-07 124 99 7998 0650 - 94 52 8415 1283 147-67 6841 1673 -115-31 Weighted mean V-.. -1 25-81 11-83 14 28 Vd Curvature. . . Radial velocity - 138' 1 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 433 1908. July 11. G. M. T. 16 1 ' 58'" e HERCULIS 1093.* Observed by J. S. PLASKETT. Measured by W. E. HARPER. Mean Corrected Displace- Mean Corrected Displace- Wt. of Settings. Stai Settings. ment in Revolutions. Velocity. Wt. of Settings. Star Settings. ment, in Revolutions. Velocity. i 54 6857 14 27 2729 '3166 0960 83'33 ?. 53-8389 8908 0790 -90-93 2 27 2031 J 53-0466 1 H'6737 '7328 1186 -88'83 2 45-2135 2 H'4481 1 45 1326 1927 0460 48-02 Weighted mean -80'67 V a :. -11-83 Vd -14 Curvature ... .....-' 28 * Check measurement. 1908. July 13. G. M. T. 16 h 19> Radial velocity -92'9 e HERCULIS 1699. Observed by J. S. PLASKETT. Measured by J. B. CANNON. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 72-9161 1 27'3386 '3706 0513 + 44-53 72'7*>81 8611 0037 - 5 37 2* 27 2138 72-3520 14 11 8957 9057 0543 -t-40'67 45-2128 ? 11 '4945 45-1745 . 2353 0034 - 3-55 Weighted mean +22'00 V a -12-28 Vd. - - '14 Curvature ... . - " 28 1908. July 13 G. M. T. 16" 19'" Radial velocity, e HERCULIS 1699.* + 93 Observed by J. S. PLASKETT. Measured by W. E. HARPER. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 1 72-8786 1 52'9980 72-7355 "8648 oooo O'OO 2 45-1721 72-3211 1 45-1655 2670 0283 + 29-54 2 54-6267 ....... .. 14 11 8675 9317 0803 + 60 14 1 53-8710 '9856 0158 + 18'18 ? H'4430 Weighted mean +34'48 V a -12-28 Vd - '14 Curvature. . . - '28 * Check measurement. 86030} Radial velocity +21'8 434 DEPARTMENT OF TEE INTERIOR 9-10 EDWARD VII., A. 1910 1908. July 14. G. M. T. 'I7 h 42 m e HERCULIS 1707. Observed by W. E. HARPER. Measured by J. B. CANNON. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star r ment in Velocity. Settings. Settings. Revolutions. Settings. Settings. Revolutions. 1 72-9823 2 45-2751 1 72-8174 8454 0194 -28-15 2 45-2115 2100 0287 29.96 1 72-4157 2 27-4009 3709 "0417 36 20 2 54-7221 2 27-2759 ft 53 9413 9573 '0125 14 39 2 11-8686 8106 0408 30-56 2 53 0976 2 11-5667 Weighted mean -30'50 V a -12-58 Vd - -19 Curvature .... '28 Radial velocity , - 43 6 1908. July 15. G. M. T. 17 h HERCULIS 1712. Observed by\ Measured by / Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. H> HO) IM 74 0127 L2 : 1 57-7351 8188 0080 - 9-63 1 27-3058 3850 0270 23-91 Q 57 '5079 2 27-1684 2 54-6556 1 H'7612 8374 0140 10-49 11 53 "8752 9665 '0033 - 3'80 2 1T4310 Weighted mean . Vd ...... Curvature. - 8-20 - 14-35 00 28 Radial velocity REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 437 1908. July 25. G. M. T. 17 h 20'" HERCULIS 1728. Observed by J. S. PLASKETT. Measured by W. E. HARPEK. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 54-8772 . 14 45-3992 2740 "0353 + 36'85 2 2 54 1331 53 2387 0021 0323 + 37-18 1 2 24-5975 24-3793 4648 0522 + 45 31 2 45-3988 Weighted mean + 38'89 V a - 1.4-53 Vd -22 Curvature ... - '28 Radial velocity +23'9 1908. July 26 G. M. T. 16'- 58" Observed by\ w F TT.-- Measured by / W> * UARPER - Wt. Mean . { Settings. Corrected Scai- Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. '2 73-0485 2 531465 1 72-8867 8482 0166 -24-08 2 45-3092 2 72-4827 H 45-2855 2500 0113 + 11'80 1 2 57-8605 57-8620 8279 0011 + 1-32 r 2 27-4567 27-2950 4100 0026 2 26 > 547767 14 11-8964 84% '0018 - 1'35 1 53-9981 '9635 0063 - 7 '25 9- H'5540 Weighted mean - 237 V a -14 71 Vd - .20 Curvature... - .28 Radial velocity . - 17.6 438 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 1908. July 28. G. M. T. 17 h 12 m e HERCULIS 1734. Mean Corrected Displace- Mean Corrected Displace- of Star ment in of Star ment in wt. Settings Settings. Revolutions. Velocity. Wt. Settings. Settings. Revolutions. Velocity, 2 72 '4230 I 1 45-1967 2434 '0047 + 4 91 2 59-7721 4 27-3527 3951 0175 -15'H> 2 54-7033 2 27 ' 2C43 1 53-9145 9547 0151 -17-38 l 11-7436 8210 0304 -22'77 2 53 ' 0702 2 H'4292 2 45-2269 i Weighted mean - 1 2 ' 24 V a -15-07 V<* '22: Curvature .. - '28 Radial velocity. 27'8 1908. July 29. G. M. T. 14 h 22 m HERCULIS 1737. Observed by J. S. PLASKETT. Measured by W. E. HARPER. Mean Corrected Displace- Mean Corrected Displace- of Star ment in of Star ment in Wt. Settings. Settings. Revolutions. Velocity. Wt. Settings. Settings. Revolutions. Velocity. 2 72'9830 1 29-8960 9563 0333 + 32'10 1 72-8682 8968 0320 + 46-45 2 29-8627 1 72-4145 A 27-3845 4478 '0352 + 30"55 2 54-6912 ?r 27-1833 1 53-9795 0321 0623 + 71-71 H 11-8437 9232 0718 +5378 2 54-0574 l 11-6321 2 45-2190 2 11-4277 1 45-2345 2891 0504 + 52-61 Weighted mean +49'80 V fl -15-17 Vrf.... - -06 Cxirvature . . . - 28 Radial velocity + 34 3 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 439 1908. July 29. G. M. T. 15 h 08 ra e HERCULIS 1738. Observed by J. S. PLASKETT. Measured by W. E. HARPER. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. , ' 54-7011 1 45-2290 2753 0366 +38-21 1 53 9824 "0240 0542 + 62. 3s 2 29-8783 2 53-0696 1 11-8603 9186 0672 + 50-35 2 45 2273 2 11-4489 Weighted mean +50'31 V a -15-17 Vd - -11 Curvature . . - " 28 Radial velocity. + 34-; e HERCULIS 1743. 1908. July 29. Observed by J. B. GANNON. G. M. T. ' 18 h 05 m Measured by W. E. HARPER. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 2* 2 3 73 0345 72-8884 72-4567 54-7492 54-0298 2 2 2 1 54 0317 53-1037 45-2694 45-2692 0317 0619 ^71-25 8670 0022 + 3-19 2734 0347 +36-23 Weight' V C ;d mean . + 65-91 - 15 17 25 - "28 d urvature Radial velocity + 40'2 1908. July 30. G. M. T. 17 h 06" e HERCULIS 1746. Secured by} W. E. HARPER. IrVt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. a 54 '7460 2 45 2629 2 '2 53-9640 53-1102 9628 0070 - 8-06 i 45 2283 2390 0003 + 31 Weighted mean 6 " 47 V a - 15-27 V~ 72 3735 2 45 2615 7 54 7063 \ 45-2510 2631 0244 + 25-47 Weighted mean + 34'86 V a -16-17 Yd -19 Curvature '28 Radial velocity + 18"2 1908. Oct. 2. G. M. T. 12 h 23" e HERCULIS 1905. Observed by T. H. PARKER. Measured by W. E. HARPER. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 73'0219 . 1 54-0557 9920 0222 + 25'55 i 72-9047 '8923 '0275 + 39-90 2 45-3540 2 72-4605 li 45-3672 2868 0481 + 50-22 2 54 0925 Weighted mean +40'28 V a .'. -16-17 V d 19 Curvature .. .... - "28 * Check measurement. 1908. Oct. 2. G. M. T. 13 h 18" Radial velocity . HERCULIS 1906. 23 6 Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. ; 72 '9878 2 45-2706 A 72 8491 '8716 0068 + 9'86 1 45-2536 0179 + 18-69 1 2 72-4218 \ 27 4469 3999 0127 -11-02 ) 54-7350 a? 27-2936 - 53.9915 53 ' 10fl 9095 0297 + 34-18 , 4 15-5485 15-4700 4771 0040 + 2-93 - Weighted mean +12'22 V....V Curvature. . Railial velocity. -16-17 23 - '28 - 4-4 446 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 1908. Oct. 2. G. M. T. 13 h 18 e HERCULIS 1906. ' Observed by T. H. PARKER. Measured by W. E. HARPER. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected j Displace- Star >j ment in Settings, i Revolutions. Velocity 2 2 4 2 I 73 0126 72-8790 72-4515 54-0508 53-9882 ,* f 45-2729 45-3031 27-4884 27-3237 2434 0047 + 4-81 8759 0111 + 16-11 4016 0110 - 9'55 9662 0036 - 4-14 Weighted mean + 1 ' 15 V a -16-17 Vd.. - -23 Curvature . . " 28 * Check measurement. Radial velocity -15 5 1908. Oct. 5 G. M. T. 12 h 45" e HERCULIS 1917. Observed by T. H. PARKER. Measured by W. E. HARPER. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity i Settings. Settings. Revolutions. Settings. Settings. Revolutions. 2 53-9338 1 53-9042 9992 0294 -i-33'8^ Weighted mean +33'84 V B -15-21 Vd - -22 Curvature . . . - ' 28 Radial velocity -i 18" 1 1908. Oct. 12. G. M. T. 14 h 15" e HERCULIS 1926. Observed by | T p A1 > KR1 , Measured by/ 1 ' H. PARKER. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocit Settings. Settings. Revolutions. Settings. Settings. Revolutions. 2 54-7809 2 45-3392 * 53-0112 9684 0014 - 1-61 i 45-2745 2089 0298 -31-1 2 53-1586 Weighted mean - 16 '36 V a -12-99 V d - '28 Curvature i . . '28 Radial velocity -29'9 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a e HERCULIS 1926.* 447 r.*ix. Oct. 12. Observed by T. H. PARKER. G. M. T. 14 h 15 m Measured by W. E. HARPER. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 2 2 72 9282 72-7570 72-3640 53-9777 1 2 53-9142 45-2412 45-1955 9648 0050 5'55 8388 6265 ! -38'4f 2281 0106 -11-06 19 G Weigh ted mean 11 73 12-99 28 28 25-3 PER. V a Curvatur ' Check measurement. Radial veloci e HERCULIS 1961. >S. Xov. 13. O M. T. 10 h 33 M e yy bserved by) w v ^ easured by/ W - ^ HAB Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. :mgs. Settings. Revolutions. Settings. Settings. Revolutions. 2 72-9540 U 45 1868 1763 '0725 75'91 A 72-7900 7980 0207 -30 08 27-4609 4488 0394 34-36 2 72 3992 2 27-3340 2 r>4 0249 i H'8665 '8626 1378 -103 '76 1 54 9106 9010 0556 64-16 f 11 6620 2 45 2941 Weighted mean - 62'07 V a - 4-70 Vd - '23 Curvature ... - '28 1908. Xov. 13. G. M. T. 10 h 33 m Radial velocity -67'3 e HERCULIS 1961.* Observed by W. E. HARPER. Measured by T. H. PARKER. Mean ; Wt. of i Settings. Corrected Star Settings. Displace- ment in ' Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions;. Velocity. I 2 72-9915 \ 72-8067 i 2" 72-4317 ! 2 i 54-7682 1 53 9192 2 53-1417 2 2* 1 1 2 48-8173 48-1143 45-3301 45-2254 27-4192 27-3324 8233 0415 -60-22 0670 1689 3334 0698 0792 72-87 -67 74 3912 0603 62-42 4" Weighfc C * Check measurement. Radi< 25a31 ed tr,ean 66-75 4-69 25 28 r a ;. r d 'urvature - il velocity 71-8 448 DEPARTMENT OF TEE INTERIOR 9-10 EDWARD VII., A. 1910 1908. Nov. 13. G. M. T. 10 h 33" e HERCULIS 1961.* Observed by W. E. HARPER. Measured by J. B. CANNON. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 72-9300 2 53-0847 i 72 7524 7849 0338 -48'ii 2 45 '2672 o 4 72-3700 1 45-1730 3394 0593 C2'09 2 54-7057 \ 11-8557 8791 1213 -01-95 4 53 '8622 '8807 0759 87 '59 2 11-6345 * Check measurement. 1908. Nov. 26. G. M. T. 10 h 07" Weighted mean - 68'24 V a - 4-70 Vd - 23 Curvature ... - ' 23 Radial velocity. e HERCULIS 1983. Observed by W. E. HAMPER. Measured by J. B. CANXON. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity . Wt. Mean .of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 2 2 ,* 1 72-9887 72-4267 57-8410 57-8284 54-7670 53-9637 2 2 2* 2 53 1422 45-3295 45-2686 27-3610 11-6692 2237 0250 -26-17 7837 0210 -25-32 9227 0339 39-12 Weight \ \ C ed mean 29-54 79 25 28 'a. urvature Radial velocity -30'9 HERCULIS 1993. 1908. Dec. 2. G. M. T. Il h 05" Observed by J. B. CANNON. Measured by W. E. HARPER. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt, Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity 2 73 0015 2 54-0327 "9273 0159 18'2E l 72 '8197 '7353 0368 -53 51 2 45-3945 72 '4371 1 45'3182 '2173 '0416 -43 68 2 54-1072 Weighted mean - 30 57 V a + 1'12 Va - 28 Curvature ... - ' 28 Radial velocity -30'0 REPORT OF THE CHIEF ASTRONOMER 449 SESSIONAL PAPER No. 25a 1909. Feb. 8. U. M. T. 22 h 08 HERCULIS 2263. Observed by \ w K w, RP ,. H Measured by J ^ ' K ' HARP *- H - Mean Wt. of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 ; 7 '8987 1 45 '2382 1897 '0692 79 "51 i 72 7145 2~ 72 3414 7305 0416 -60 49 i 2 27-5582 27-4495 5058 0560 49-56 2 : 54 0360 I 12'1170 1096 0391 -29'56 1 53 9233 8891 '0541 62 '57 2 1 H'8145 2 45 3421 Weighted mean - 60"54 V a + 17-19 V d + -16 Curvature... - '28 Radial velocity - 43 "5 1909. Feb. 8. G. M. T. 23 h HERCULIS 2264. Observed by\ w Measured hyj I W ' Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings. Settings. Revolutions. Settings. Settings. Revolutions. 72 8680 1 45 2202 2118 0471 -54-12 i 72 6942 7400 0321 -46-67 1 27-5152 5061 0551 -49-29 1 72'3157 2 27'4062 2 54 ' 0053 1 12-0368 0711 0776 -58-66 li 53 ' 8918 "8878 0554 -64 07 2 11 ' 7743 i 2 45-3020 Weighted mean - 56'30 Vo. + 17-19 Vd + -12 Curvature '28 Radial velocity - 39-3 450 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 e HERCULIS 2305. 1909. Feb. 22. Observed by J. B. CANNON. G. M. T. 21 h 34 m Measured by W. E. HARPKR Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 ,* 2 i 1 72-9872 72-8275 72-4233 57-8428 57-8125 54-0565 2 J 1 i 2 53-9658 45 3275 45-2636 27-4794 27-3812 9111 0321 -37-13 7571 0150 -21-81 2295 4953 0291 0665 -30-87 -58-22 7522 0303 -36 63 Weight< R ?d mean . . 36-09 28 V a + 17-95 + -15 Vd Curva adial veloc- burt? tv .. - 18'2 HERCULIS 2306. 1909. Feb. 22. G. M. T. 22" 36 ra Observed by J. B. CANNON. Measured by W. E. HARPKR. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Resolutions. Velocity. 2 ! 4 1 2 2 1 72-9687 72-8071 72 4092 57-7942 57-8290 54-0450 53-9530 2 1 \ 2 1 2 45-3155 45-2637 27-5020 27-3725 11-9835 11-7002 7544 0177 -25'74 2415 5276 0174 0342 -18-27 5 -29 <)3 7477 0348 -42-05 0905 0582 -44 00 9100 0332 -38-40 Weight* R ;d mean -. 34 12 28 V a + 17-95 + '09 Vd. Curva adial veloc ure.. tv .. - 16'4 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 451 1909. March 2. G. M. T. 21 h 12" HERCULIS 2327. Observed by J. B. CANNON. Measured by W. E. HARPER. Wt Mean of Settings . Corrected Star Settings . Displace- ment in Revolutions. Velocity. Wt. Mean of Settings . Corrected Star Settings . Displace- ment in Revolutions, Velocity 2 72 it387 2 45-2988 i > 72 8030 72-3801 7800 0079 + 11 49 *, 45-3043 12-0685 2991 1891 0402 0404 + 42-21 + 30'54 <> 54-0227 2 11-6875 g * 53-9890 9681 0249 +28'70 Weighted mean +31 '76 V a +17-90 V d + '14 Curvature . . - 28 Radial velocity .' + 49'5 1909. March 2. G. M. T. 22 h 26 m e HERCULIS 2328. Observed by J. B. CANNON. Measured by W. E. HARPER. 1 1 Mean Wt. of ! Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings . Displace- ment in Revolutions. Velocity. 1 1 53-9935 2 45 '2644 1 ! 53-9260 9343 0091 10 52 i 45-2350 2642 .0053 + 5-56 Weighted mean 5" 16 V a ..... . +17-90 V d + '05 Curvature ... " 28 Radial velocity. + 12-5 1909. March 13. G. M. T, lS h 35 HERCULIS 2370*. Observed by J. S. PLASKKTT. Measured by J. B. CANNON. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings . Settings . Revolutions. Settings . Settings. Revolutions. 2 50-9370 i 34 7430 34 7193 -1038 -100-00 1 50-8242 80S1 0804 -93 05 9! 34-6975 Weighted mean -95'36 Va +17-44 Vd + "19 Curvature '30 Radial velocity - 78 This plate and all following \\ere taken by the new single-prism Spectroscope. 452 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 1909. March 13. G. M. T. 19 h 23 m e HERCULIS 2371. Observed by J. S. PLASKETT. Measured by J. B. CANNON. Wt. Mean of Settings . 58-8462 58-7184 50-9411 Corrected Star Settings . 6911 Displace- ment in Revolutions. 0741 Velocity. -94-51 Wt. Mean of Settings. 50-8549 34-7589 34-6926 Corrected Star Settings. 8347 7401 Displace- ment in Revolutions. 0538 .0820 Velocity. -62-27 -79-00 Weighted mean - 71 " 66 V a +17-44 Vd + '19 Curvature '30 Radial velocity. - 54-3 1909. March 15. G. M. T. 19 h 32 m e HERCULIS 2384. Observed by W. E. HARPER. Measured by J. B. CANNON. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in . Velocity. Settings. Settings. Revolutions. Settings. Settings. Revolutions. 2 58 '8228 2 50-9196 k 58-7768 7729 0077 + 9*82 k 50-9081 9094 0209: -24-19 Weighted mean ... + 19 ' 40 V a +17-16 Vd + '18 Curvature ... - " 30 Radial velocity +36'4 1909. March 15. G. M. T. 20 h 30 e HERCULIS 2385. Observed by W. E. HARPEK. Measured by J. B. CANNON. Mean Corrected Displace- Mean CoiTected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings. Settings. Revolutions. Settings. Settings. Revolutions. 2 58 '8349 1 50 9261 9091 0206 . + 23-84 i 58-7924 7764 0112 + 14-29 I 34-8678 8413 0192 + 18-50 2 50 '9379 2 34-7003 Weighted mean +21 36 V a +17-16 ' Vd + '18 Curvature '30 Radial velocity +38'4 REPORT OF TEE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 453 1909. March 21. G. M. T. 20 h 05" e HERCULIS 2454. Observed by\ T T> Measuredbyr LB - Mean Corrected Displace- Mean Corrected Displace- wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings. Settings. Revolutions. Settings. Settings. Revolutions. 2 58-8306 1 50 9084 9091 0206 + 23-84 A 58T836 7720 0068 + 8'67 * 34-7992 8274 0053 + 5-11 2 50 '9202 2 34-6456 Weigh ted mean . . 4 15-34 14-93 06 V a Vrf . Curvature '30 Radial veloci e HERCULIS 2455. 1909. March 31. G. M. T. %P 39 ty 4 30 S'NON. Observed by'\ T T> p, A Measured by J J - B ' CA Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Displace- Star ment in Settings. Revolutions. Velocity. 2 58-8294 58-8022 50 9229 I* 50 9111 34-7789 34 6522 9091 -0206 8005 '0216 +23-84 -20-90 7917 0265 +33-80 Weighted mean . V 4 15 15 14-93 06 4 Vd 4 Curvatur e - -30 Radial velocity +29'i 454 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 OBSERVING RECORD AND DETAILED MEASURES OF 77 BOOTIS. P. PLASKETT. PI. PARKER. RECORD OF SPECTROGRAMS. H. HARPER. C. CANNON. T. TRIBBLE. i 1 TEMPERATURE. .5 |EH c3 X Hour Star. O> fc . Plate. Date. "o . j Angle at end. Room. Prism Box. | Seeing. 4 ! > h a r^ i* \ i 1 1 1 Q Beg. End. Beg. End. 58 J5 C 1906. h. m. m. h. m. Fahre nheit. Centi grade. TjBootis . 308 IL Seed 27 . June 25 15 55 35 3 30W. 650 64 22-7 22'8 001 jPoor .. P n 313 ,, n n 27 14 35 35 2 15W. 75-6 74-0 27'1 27-0 001 Fair. . . . P n 318c n ., 29 14 21 18 2 10W. 77-4 76'2 27'0 27-0 0009 n . . P n . . 326 u n July 4 14 50 60 3 15W. 62-5 60-9 21-3 21-4 001 Fair to good . . P n 333 n i 6 15 00 70 3 40W. 71-5 68-0 25'3 25'4 001 Fair. . . . P ii 366 u n Aug. 6 14 05 70 4 45W. 78'0 74'0 28'8 28'8 001 Good... P u .. 372 " " 8 14 15 75 5 10W. 80 8 77 5 29'5 29'3 001 Fair.... P 1907. n 657 n Mar. 8 18 45 30 50E. 26-5 25'6 1-3 1-5 0013 Fair... P n 670 it 20 18 32 45 10E. 28-6 28'3 2'8 2'9 0013'Good... P n 691 n Apr. 3 18 02 35 15W. 44'0 40-2 9'8 10-1 001 JPoor ... P n 731 n - n 19 18 35 10 1 37 W. 34'8 34-5 10-4 10-4 0013 Clouds. P n 739 n n 26 17 30 30 1 07W. 42'0 40'4 9'0 9'0 0013 Fair.... P n 752 t, M May 7 14 20 20 1 30E. 50-5 50'0 16'1 16-1 0013 .. H Centi grade. n . . 760 IIIL n 14 17 55 34 2 05W. 11-7 11-7 15'0 15'0 0012 Very poor . . H n 764 it n 20 16 25 55 1 45W. 6'0 5'3 9'2 9'2 0012Unst'dy H n 769 n ti n . 22 16 51 47 2 20W. 10-5 10-5 13-2 13 2 0012 Cloudy. P n 774 IL ii ,. 23 1-1 08 16 37 E. 15'5 15-0 17'3 17'3 0012 Fair.... H n 779 n n ,. 24 15 01 12 20W. 11-8 12'0 16'4 16'4 001 Good... P n 793 H n 29 16 46 27 2 SOW. 80 8'0 14'5 14'5 001 Cloudy. P n 797 n 31 14 54 12 45W. 15-2 15-2 19-0 19'0 001 Good... P u 812 n June 10 13 35 35 1 48W. 16'6 15'6 18-2 18-0 0009 .. P n 868 ,, ii n 21 14 27 25 1 40W. 25'4 24 6 28 9 28-9 001 Hazy .. P n 891 ,, n 27 14 55 30 2 35W.J 22'0 22-0 24'5 24'5 0012 Fair ... H n 918 n July 8 15 09 18 3 30 W. 21-5 21-1 22-4 22'4 0012 ... P M . . 950 It n 18 13 57 26 3 OOW. 27-0 26-0 28'5 28'5 0012 Very hazy. . T n 972 u .. Aug. 1 13 39 25 3 37W. 22'2 21-0 25'2 25-2 001 Hazy .. H u .. 990 IIIL n 7 13 58 50 4 SOW. 23-1 22 24't 24-1 0015 Poor ... P 1908. u 1231 IL Jan. 14 22 00 26 1 10E. 16'5 18-0 5'2 - 5-5 001 Hazy. . . H n 1294 IIIL ti 27 20 12 50 1 52E. 20-0 18-0 15-3 15-3 0013 Good... H n 1307 ,i ii 29 21 14 62 1 07E. 25 '3 25'5 -13-7 IS'7 0013Unst'dy P ii 1332 ,, n Feb. 17 22 30 40 1 45W. 17-5 18-0 10 '5 10 5 0015 Good... P n 1357 ,, n 24 19 06 47 1 20E. 16-5 15-5 19-0 18-6 0013 Unst'dvi H n 1446 n Mar. 30 20 52 40 3 50W. 0'5 0-5 6-0 6'0 002 Fair...'. H n 1513 ,, u May 4 18 13 55 2 40W. 8-0 7'0 13-4 13'3 '0017 Good .. FH i 1553 n 25 15 58 64 1 50W. 21 3 20-5 25'6 25'4 -0016 ... P 1 i 1557 ,, n 23 16 00 50 1 45W. 21'5 20'7 25'7 25'6 '0015 Fair. . . . P i 1621 n June 22. 14 10 30 2 35W. 20'0 19'6 24-0 23'8 '0015 P i 1663 n July 6 14 40 80 3 25W. 25'3 24 8 26'8 26'3 0015 Good.!! P i 1710 ,, n 15 14 41 102 4 11W. 19'5 18-0 21-8 21-6 0015 Cloudy. C i 1792 ,, Aug. 19 13 18 60 4 47W. 18'8 16'5 24 3 23-8 0018 Good... H i 1867 " , n . . Sept. 7 12 57 65 5 40W. 18'2 17'6 21-4 21'2 0015 Fair.... P 1909. M 2115 1! n Jan. 7 23 23 60 10W. -20'0 -20-5 13-6 13-6 0016 Fair... P n 2209 ,, it 30 18 37 45 3 20E. 8'3 8-5 2'8 2'9 '0016 Unst'dy P n 2283 n Feb. 17 20 30 62 00 -12-0 12-0 - 1'3 1-3 '0015 Good.T. C n .. 2396 " it Mar. 20 17 00 60 1 30E. - 2'3 - 33 4'6 4'6 '0015 Fair ... P REPORT OF THE CHIEF ASTRONOMER 455 SESSIONAL PAPER No. 25a 1906. June 25. G. M. T. 15 h 55 ra i? BOOTIS 308. Observed by J. S. PLASKETT. Measured by J. N. TKIBBLE. Mean of Settings. Computed Wave Length. Corrected Wave Length. Normal Wave Length. Displacement in Revolutions. Velocity. ] Mean of Settings. Computed Wave Length. Corrected Wave Length. Normal Wave Length. Displacement in Revolutions. Velocity. 65'1413 4583-661 1 1 46 0370 4376-165 62-3546 60 '7590 4550-101 4531-441 165 '473 766 201 399 '272 + 26-28 17'99 if 1 1 45-4280 41-8841 4370-332 4337-216 276 856 420 30-61 60-5605 60-0525 57-5179 4529-147 4523-302 4494-721 171 318 807 055 '364 263 24-10 17-43 I 39-8944 39-7049 39-4547 4319-219 4317-527 4315-298 191 503 817 068 374 "435 38-64 30-21 54-9606 4466-816 I 39-4909 4315-620 600 178 422 29 33 54-2971 4459-723 651 304 '347 23 32 9 l 37-0639 4294-322 54 2685 4459-366 9 33-1023 4260-796 820 503 317 22-30 53-8823 51-2524 49-0104 4455 320 4427-927 4405-271 240 855 199 962 420 '951 278 435 320 18-71 29-45 21'78 1 29-7582 31-9013 22-9884 4233-629 4250-924 4181-569 685 972 462 643 223 329 15-79 + 23-21 ' Weighted mean +23'08 V a -24-87 Vd - -25 Curvature "28 Radial velocity. - 2-3 1906. June 27. G. M. T. 14 h 35' r, BOOTIS 313. Observed by J. S. PLASKETT. Measured by W. E. HARPER. 4 a > c cS q-j *> c8 -w Mean of Settings. Computed Wave Length. rected W ength. L If placemen Revoluti | Mean of Settings. Computed Wave Length. o si g if g placemen Revoluti | *^ 0^ .2 c 3 -4-5 **"! 0^ .2 c 8 O JK Q " ^ O O " r 2 70-0228 4549-704 1 58 7715 4425-974 982 608 374 25 31 2 70 0646 4550-199 *i43 766 377 + 24.84 2 57-7472 4415-579 571 244 327 22 20 2 68-8922 4536-420 '408 965 443 29-28 2 56-7110 4405-198 194 951 243 16-80 1 68-4773 4531-556 '552 23'13 '?S 56-6837 1 68 3445 4530-057 057 '784 273 18-04 2 55-7498 4395-689 696 286 410 27-96 2 68-2790 4529-300 297 '807 -490 32-38 1 54-5449 4383-928 970 720 250 17-07 8S 68 2356 1 54 5162 4383-650 1 67-7616 4523-337 345 855 490 32-38 1 53-1281 j 4370-320 356 856 500 34 30 3 65-2295 4494'746 1 52-9142 4368-285 320 840 480 32-92 1 64*1575 4482*928 924 434 490 32-88 2 51-2105 4352-272 312 006 306 21-08 1 63 '580 4476 '631 '631 ' 91A '420 28 "09 3 48 ' 3264 4325'902 > 63-5399 4476-193 2 47-8181 4321 348 368 992 376 26-05 1 63-2805 4473-381 377 957 420 28-10 2 47-1641 4315-529 545 178 367 25 46 2 62 ' 6605 4466 698 3S 46-3197 2 59*7122 4435-639 654 184 470 31-77 1 46-3142 4308-296 296 023 273 18-97 1 58-9422 i 4427-710 730 420 310 20-98 2 46-1418 4306-521 513 153 360 + 25-02 \Veighted mean +25*87 V -25-19 Vi - *14 Curvature '50 Radial velocity . . . o-o 456 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 1906. June 29. G. M. T. 14 h 21 m 77 BOOTIS 318c. Observed by J. S. PLASKETT. Measured by J. N. TRIBBLE. > o5 9 > M 0> 4^ S 3 S ^ 93 c '5 & 5 C-43 Mean Computed T) _c ^ Mean Computed BrS of Wave *" 1i > g of Wave 2 ~hr s> |j Settings. Length. hi O ft a ~ > 91 65-1913 4584'OIS 46-8204 4383'596 2" 62-3803 4550-121 205 766 439 +28-93 H 45-5865 4371-738 806 312 494 29-78 9, 62-3321 4549-552 1 45 4158 4370 '111 '177 856 321 22 03 60-7998 4531-584 664 202 462 30-59 1 45-2187 4368-238 302 840 462 31-84 I-'T 60-5480 4528-712 Li 42-2886 4340-901 941 634 307 21-20 a 60'0766 4523-289 377 855 522 34'61 1 J 39-4436 4315-255 14 57-5359 4494'635 1 38-6660 4308 394 390 023 367 25-53 11 54 2713 4459 ' 185 S 37-0462 4294 ' 299 53-9012 4455-264 384 962 422 28-40 1 35-7398 4283-122 ioe 721 385 26' 95 1 51 ' 5610 4430'869 985 '678 '307 20 '78 11 33 ' 0517 4260'643 2 50-0623 4415-601 709 293 416 28-25 28-9306 4227-475 463 010 453 32-12 H 50-0089 4415-084 1 25 2131 4198-823 819 403 + 28-78 9 49-0242 4405'227 '331 '951 '380 25 '87 22 '9474 4181-919 1 46-8536 4383-917 001 720 281 20-02 Weighted mean + 27 " 55 V a - 25-31 Vd - '14 Curvature - '28 Radial velocity + 1-8 i) BOOTIS 326. 1906. July 4. Observed by J. S. PLASKETT. G. M. T. 14 h 50 m Measured by W. E. HAKPEK. 2 1 2 2S 2 1 3 1 2 2 2 2 1 2 Mean of Settings. Computed Wave Length. Corrected Wave Length. Normal Wave Length. Displacement in Revolutions. "a3 1 1 2 2 2 3 2 1 2 3 3 3S Mean of Settings. Computed Wave Length. Corrected Wave Length. Normal Wave Length. Displacement inRevolutions. ' ,! > | "S E> ; 47-9535 72-9821 72-0410 70-1726 70-1316 68-9985 68-3839 68-3512 67-8624 65-9783 65-3427 63 6949 63-6582 63-3995 62-7750 62-8070 62 6324 4321-280 4584-067 4572-552 4550 127 292 992 300 + 20-97 62'1243 61-7085 61-3025 59-0672 57-8787 56-8425 56-8102 55-8790 54-6865 54-6501 53-4072 53-0457 51-3477 50-1222 48-4705 47-3080 46-4662 4459-686 4455-266 4450-975 4427-735 4415-645 4405-249 724 300 097 743 638 251 304 962 654 420 293 951 420 338 443 323 345 300 28-22 22-74 29 'SI ' 21-86 23-42 20-43 528 126 156 766 372 360 24-32 23 68 4536-325 4529-186 4528-807 4523-173 4501-798 4494-706 4476-593 4476-195 4473-387 4466-648 4466-982 4465-118 325 187 965 807 360 380 23-79 25-15 4395-702 4384-041 4383-688 4371-721 4368-273 4352-284 4340 944 4325-922 4315-523 710 060 286 720 424 340 28-91 23 25 ; 165 786 855 448 310 338 20-55 22-47 752 300 308 960 312 840 006 634 440 460 302 326 30 18 : 31-55 20-80 22-49 584 214 370 24-75 407 957 450 30-15 061 158 771 712 290 446 19-45 29-92 523 i'78 345 + 23 94 Weighted mean + 24'70 V a - 25-68 Vd - -21 Curvature '50 Radial velocity - 1-7 REPORT OF THE CHIEF ASTRONOMER 457 SESSIONAL PAPER No. 25a 1906. July 6. G. M. T. 15 h O" BOOTIS 333. Observed by J. S. PLASKKTT. Measured by J. N. TRIBBLE. e3 i 4 a> a ^ a B-2 *> i > -J-.2 Mean Computed _: f" -= Mean Computed 5& ~ of ^ ave _ s * jj-. of Wave S +3 _ -u 8 > >, Settings. Length. a foS "c Settings. Length. ~c a a; ttf | 6 fc .2 c p- J 6 1 ft-S 0) 65 '1677 4584-687 .... a 49-0105 4405-903 '327 951 376 25 "60 64.2090 4572-978 370 156 214 -14-03 2 49-9783 4415-602 62'3')21 4550-733 149 766 383 25 23 li 46-8362 4384 534 958 720 .238 16-28 62-3108 4550-244 1 46-0199 4376-656 60 7739 4532-258 690 202 488 32 27 a 45-2045 4368-866 298 840 458 31-43 60-5228 4529-354 I 42 2765 4341 509 '949 634 315 21 "66 57-5196 4495-363 |3 39 4279 4315-792 54-8062 4465-776 200 972 228 15 31 a 38-6559 4308-969 425 023 402 29-97 54 5412 4462-942 366 977 .389 26 15 2 37-6252 4299-954 54-2551 4459 893 1 37-0706 4295-148 '620 273 '347 24'22 53-8852 4455-966 390 '962 428 22-07 33-0446 4261-155 53-4774 4451-659 079 597 482 32-45 2 33-0766 4261419 923 523 .400 28-14 51'5374 4431-472 888 678 210 14-21 I i 1 28-9090 4227-803 371 010 .361 25-59 51-2451 4428 473 .893 420 473 32-02 2 24-3115 4192 463 103 678 .425 +30-37 51-0727 4426'719 135 805 330 22 37 i 22-9363 4182-232 50-0457 4416-282 702 409 27-76 Weighted mean +24-60 v a . - 25'76 Vd - '21 Curvature - -28 Radial velocity. . . - 1-7 1906. Aug. 6. G. M. T. 14 h 5 m BOOTIS 366. Observed by W. E. HARPER. Measured by J. N. TRIBBLE. >, Mean of Computed Wave "85 *" U! ll > Settings. Length. o> t if aj Q; apa 8 Settings. Length. 8 c S^ ' S ^ ts g O 1 "" 1 6 % 5- a > * fc e- > 65-2314 4584-018 n 46-8746 4383-831 871 720 151 10-42 64-2565 4572-121 ii 46-8483 4383 577 62-4060 4549-971 .039 766 273 + 18-00 r 45.6093 4371-677 707 312 395 27-11 62-3706 4549-552 1 1 45 2419 4368-182 210 840 370 25-38 60-8339 4531 583 495 '202 293 19'38 i ~ 16-0709 4376-090 60-5846 4528-704 1 -i 42 3186 4340-924 936 634 302 20-85 60-1077 4523 221 "307 '855 "452 29-97 1 1 39 46% 4315 '255 57 5747 4494-670 38-6818 4308-308 296 023 273 18-99 53 9251 4455 ' 161 "247 962 2'(5 20 '18 > 37 "0702 4294'292 53-5350 4451 ' 047 131 '597 "534 35'98 a 33 '0764 4260-658 54-3107 4459-249 u 28-9385 4227-371 349 oio 339 24-03 51-5845 4430-779 859 678 181 12 25 25-2344 4198-838 830 403 427 28-48 50.0855 4415-538' 602 293 309 21-09 i 24-3315 4192-055 047 678 369 +26 37 50-0371 4415-051 ^ 22-9657 4181-919 49 0520 4405 195 251 951 300 20-42 Weighted mean . V a .. + 23-28 Curvature . Radial velocity . . -23-23 - -21 - -28 - 04 458 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII.. A. 1911 7? BOOTIS 372. 1906. Aug. 8. Observed by \ w p HARPF;I G. M. T. 14 h 15 Measured byj w " " HAR1 5 Mean of Settings. Computed Wave Length. > 1 1M - _IJ w %> g 8^ o eg *.a If S o> cJ 00 -tf O si 11 a* .2 a 5 1 u > i Mean of Settings. Computed Wave Length. 1 "S-S *g p o D L If BI-I fc c'43 2 2 1 2 3 38 2 2 8 1 2 2 3 2 3 1 2 2 2 1 2 2 72-9730 71-4967 71-3535 70-6887 70-1445 70-1072 68-9701 68-3516 68-3336 68 0462 67-8440 65-9487 65-3170 64-1450 63-6316 63-0377 62-7485 62-7757 62 0833 62-0545 61-2637 59-7795 4584-279 4566-264 4564-535 4556-559 4550-083 2 3 3 3S 2 2 1 1 1 1 2 2 2 3 2 2 3S 2 2 2 1 59 0301 57-8275 56-7962 56-7738 55-8252 54-6369 54-6080 53-3464 53-1912 52-9897 52-1188 52-0196 51-2852 48-4145 47-1450 48-4512 46-3963 44-8470 44-8210 44-1405 42-5767 4427-683 4415-472 4405-149 683 456 149 420 244 951 263 212 198 17'SO, 14'43i 13-48 i ii4 726 388 + 25-33 539 083 202 766 337 317 22-14 20-85 4395-551 4383-963 4383 683 4371-570 4370-093 4368-180 4359-963 4359-033 4352-180 4325-973 4314-668 4326-302 '567 995 286 720 291 275 19-84-f 18 81 4536-273 4529-077 4528-881 4525 563 4523-237 4501-743 4494-693 4481-782 4476 186 4470-518 4466-650 4466 943 4459-540 4459-233 4450-865 4435-386 233 017 965 807 268 210 17-71 13-90 602 125 210 979 050 180 312 856 840 784 732 006 290 269 370 195 318 174 .. it* . 89 ; 18-45 25-38 ! 13-41! 21-87! 11 9*1 t 505 177 743 295 855 431 210 322 312 13 95 21-24 20-74 806 591 215 14 38 660 270 353 -307 939 331 21-30! 22 93 : 558 300 258 17-28 983 588 771 304 212 284 14-22 19-08 4294-632 4294-409 4288-580 4275-360 552 273 -279 19'50| 500 280 134 922 366 358 25'5gl + 25'09't 9i3 406 596 184 317 222 21-33 15-00 Weighted mean +18'89 V a -22 83 V d 28 Curvature . . , - ' 50 Radial velocity. REPORT OF THE CHIEF ASTRONOMER 459 SESSIONAL PAPER No. 25a r, BOOTIS 657. l'.*:7. March 8. Observed by J. S. PLASKKTT. G. M. T. I;*- 45 ra Measured by W. E. HARPER. : ! Mean of s Computed Wave Length . Corrected Wave Length. Nonnal Wave Length. Displacement in Revolutions. Velocity. +3 Mean of Settings. Computed Wave Length. Corrected Wave Length. Normal Wave Length. Displacement in Revolutions. Velocity. i> - > 1436 3 j 70 1197 2 68-9542 - 5475 5 4181 2" >w 3585 - 3380 2 67-8226 2 65 3575 2 i 65 3175 1?; 62-8052 2" 62-6047 2 61-6695 2 61-2555 2 1 59-0292 4550-186 4549-902 4536 160 4531-415 4529-911 4529 219 4528-981 4523 022 4495-078 4494 631 4467-078 4464 920 4454-916 4450 527 4427 311 1 I 2 1 2 2 2 2 2 3 2 3 3 58-8587 57-8397 56-8292 56-7987 55-8360 54-6789 54-6412 53-3717 53-2120 51-3172 50-0839 48-4987 47-9197 46-4945 46-4645 4425-560 4415-172 4405 001 4404-697 4395'127 4383 776 4333-409 4371-145 4369-615 4351-693- 4340 245 4325-775 4320-558 4307-864 4307-596 385 033 805 293 420 260 28-43 17'65 356 '665 982 489 766 965 202 849 410 300 220 360 -27-02 19-86 14-58 23-86 601 056 951 286 350 23 J 23-83 16-00 557 625 807 855 250 230 16-57 15-25 370 152 636 786 364 720 312 856 006 634 350 160 220 220 270 23-94 10-96 15-07 15 14 18-63 270 550 280 18-67 562 642 257 130 772 962 597 420 210 320 340 290 14-07 21-54 22 88 19-63 552 992 240 16 63 793 023 230 -15 98 Weighted mea n . . -18-92 - '50 h!3 75 h '09 V/j . . Curve Radial ve n BOOTIS 670. iture , ocity - 5'6 1907. March 20 (.T. M. T. 18 3_" ' Observed by J. S. PLASKETT. Measured by W. E. HARPEB. Mean of Settings. Computed Wave Length . (! 6 > *ci fcc Displacement in Revolutions. *a3 Mean of Settings. Computed Wave Length . OJ > O as 0} "aS ti P ~ Displacement in Revolutions. Velocity. 72-9506 4583'964 3 56'7806 4404'929 71-9460 70-0986 4571-690 4549-552 762 112 350 -22-92 3 2 56-7601 55-7993 4404-724 1395-209 721 951 230 15 68 70'0827 4549'365 "436 '766 '330 21 '74 2 54'6290 4383'769 68-9205 68 5150 68 3215 4535-721 4531-010 4528-772 775 062 965 202 190 140 12-58 9-28 2 1 2 54-5986 53-1621 51-2715 4383-548 4369 660 4351-839 520 626 796 720 856 006 200 230 .216 13-68 15-78 14-86 68-3066 j 67 '7 847 4528-600 4522 ' 590 647 "635 807 '855 .160 220 10 61 14 '60 1 S 50-0474 48 ' 4494 4340-514 4325'976 474 634 130 11 01 65-3175 4494-740 91 48-4195 4325-707 659 939 280 19 38 65-2786 62 7505 4494-308 4466 699 320 51 550 230 '220 15'34 14-74 2 47-8720 46 ' 4482 4320-790 4308-150 732 992 260 IS'OO 62 7368 62-5533 4466-540 4464 583 592 772 180 12-08 3 U 46-4205 48-2000 4307-906 4271 650 843 570 023 865 180 295 12-50 20-56 61 6272 4454'717 '725 "962 '237 15 93 2 40 8897 4260'744 58-0902 57-7921 4427 252 k 4415-071 260 083 420 293 160 210 10-83 14 26 2 40-8547 4260 455 370 640 270 -18-87 Weighted mean - 1525 V a + 8. ^8 V d + "04 Curvature... "50 Radial velocity - 6'9 460 DEPARTMENT OF THE IXTERIOK 9-10 EDWARD VII., A. 1910 77 BOOTIS 691. 1907, April 3. Observed by J. S. PLASKETT. G. M. T. 18 h 02 m Measured by W. E. HARPER. a * Mean of Settings. Computed Wave Length. Corrected Wave Length. Normal Wave Length . Displacement in Revolutions. Velocity. 49 Mean of Settings. Computed Wave Length . Corrected Wave Length . Normal Wave Length . Displacement in Revolutions. Velocity. 1 2 1 1 3 2 H 2 2 2 i i 2. 1 , li 2" 1 2 2 ? 72-9612 71 9513 70-6445 70-0995 70-1085 68-9195 68-5217 68-3245 67-7992 65 3230 65-2775 63-3106 62-7485 62-5545 62-0287 61-6241 61-2216 58-9911 58-8230 57-7905 1584-046 4571-717 4556 013 4549-546 4549 612 4535 70o 4531-088 4528-809 4522 765 4494 834 4494-329 4472 793 4466-737 4464-657 4459-047 4454 755 4450-507 4427-357 4425 -C39 4415-163 ! 3 8 2 2 2 1 1 2 I 1 1 2 3 2 2 2 1 1 1 56 7745 56-7572 55-7889 54-6189 54 5876 53-3159 53-1540 51-2648 50-0325 48-4305 47-8566 47-2100 46 4200 46-4001 40-8496 40-8220 37-8036 37 0112 36-7472 4404 984 4404-812 4395-232 4383-808 4383 504 4371-275 4369-732 4351 942 4340-553 4325-995 4320--846 4315-086 4308-108 4307-932 4260-662 4260-434 4235-956 4229 664 4227-580 730 022 556 695 072 900 202 "766 965 202 170 180 210. -11-13 11-80 13-84 761 176 951 286 120 no 13-62 7'50 440 202 666 876 489 720 312 856 006 634 280 no 190 130 145 19-83 7'55 13-03 8'96 10 00 270 130 17-87. 8'62 '735 .855 120 7 96 270 737 612 550 957 772 280 220 160 18-67 14 76 10-74 '792 038 992 178 200 140 13-88 9'73 883 023 140 9 74 004 '712 467 320 605 113 304 962 597 420 805 293 300 250 130 100 200 180 20-16 16-80 8'7fi 6-77 13-54 12-22 420 962 67b 640 112 826 220 150 150 15-48 10-62 -10-65 Weighted mea V- .. n -1 2 29 50 + 2 59 00 Van + 3'70 7'58 09 50 VS.. _ Curvat Radial vel ure - - acitv . . . . - 45 1907. May 7. Observed by V-HT -p u ,,,, G. M. T. 14 h 20 Measured by / ' ^ 1AKPKB - , _ i Mean of ! Settings. Computed Wave Length. Corrected Wave , Length. L II Displacement in Revolutions. Velocity. Mean of Settings. Computed Wave Length. Corrected Wave ' Length. Normal Wave Length. Displacement in Revolutions. Velocity. 11 73-0097 H 72-0492 2 70-1677 1 70-1520 a 2 1 69 0077 IV 68-5945 3 : 68 35% 1 ' 68 3767 li 67-8727 1 j 65-7679 1 i 65-3486 i 65-3500 1| 63-3679 j 1 62-7800 I 1 62 628 j 2 I 61-6907 4584-071 4572 350 4549-830 4549 640 4536 228 4531-433 4528 720 4528-917 4523 121 4499-332 4494 672 4494-679 4472 994 4466 '663 4465 -03S 4455-067 1 3" S 2 2 2 2 1 3 H .S I 61 2811 59-0410 57-8548 56-8036 56 7947 55-8355 54 ' 6312 54-6284 53-2125 51-3040 50-0865 48-4356 47-8955 46- 4197 46-4370 40-8503 4450 747 4427-514 4415-473 4404-951 4404-863 4395-380 4383-633 43S3-606 4370 014 4352 057 4340 815 4325-827 4320-987 4307-917 4308-068 807 570 533 021 597 420 293 951 210 150 240 070 14-13 j.0-15 16 30 4'77 392 866 112 776 280 100 4-18-31 6-60 286 492 965 202 320 290 21-18 19 20 456 '720 286 720 170 000 11-62 oo 987 195 399 807 129 180 340 270 11-92 22-54 17 98 116 166 934 856 006 634 260 160 300 17-84 11-00 20-70 750 057 550 957 200 100 13 34 6-70 .122 '992 130 9-00 102 132 772 962 330 170 22-11 11 44 223 -023 200 4-13-88 1 I Weighted nit V,, .. an . 4-1 3-07 11 -12 01 ... + Vd - - Curvat ure . . . 50 Radial velocity + 0'7 462 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 BOOTIS 760. 1907. May 14. Observed by 1 w P H ., G. M. T. 17 h 55 m Measured by / v 9 n 6 03 c d 9 c3 -W Mean of Settings. Computed Wave Length. Drrected W Length. ormal Wav Length. isplacemen n Revoluti "G "2 Mean of Settings. Computed Wave Length. arrected W Length. ormal Wav Length. isplacemen n Revoluti "5 P * fi P O fc H o 77 ' 0138 4586 '749 u 60-3522 4476-077 75 0110 4572-563 402 112 290 + 18-96 r 60-3978 4476-358 438 214 224 14-03 1 74-0961 4566-168 006 726 280 18-30 i 59-8743 4473-133 223 957 266 17-84 1 72-7052 4556-546 426 202 224 14-72 i-X 51-9075 4425-754 924 608 316 21-39 1 71-7530 4550-028 906 766 140 9-22 i 48-7471 4407-805 995 851 144 9-80 1 L 71 ' 7146 4549 ' 767 ^ 48-1928 4404-704 2 68-5907 4528-772 i 42-0610 4371-304 632 312 320 +21-95 1 1 68'0928 4525'481 441 '295 146 9'66 H 38 5042 4352 659 67-7272 4523-072 035 855 180 11-92 Weighted mean ... +15 '25' V a -14 70 Vd - -14 Curvat ure - 50 Radial velo ri BOOTIS 764. 1907. May 20. G. M. T. 16" 25 m citv O'l >ER. Observed by) w v w Measured by / W ' K HARI l Mean of Settings. Computed Wave Length . JB G 6 k li fc t .a.g 1 "v Mean of Settings. Computed Wave Length . c< g "Ss 6 > -w 11 .2_a I !> 2 1" 1 2 1 l" 1 1 2 2 2 I 1 i 1 H l 4 76 8697 76-8647 76-5408 76-2327 76-0296 73-6800 72-5669 72-2842 72-0388 71 6337 71-5812 69-5846 68-4979 67 5990 65-3760 64-3050 63-2326 63-1922 61-1145 60-2770 59-7526 59-1947 58-6782 58-4205 4586-673 4586-638 4584-329 4582-137 4580-696 4564-218 4556-532 4554-592 4552-913 4550-080 4549-791 4536 314 4529 079 4522-147 4508-673 4501 799 4494-979 4494-724 4481-693 4476-506 4473-277 4469-856 4466-704 4465-137 521 208 018 191 018 618 330 190 400 + 21-52 12-39 26-08 1 1 2 2 H 2" 2 2 11 2 2" 1 J 2 2 2 2" 2" 2 2 57-5027 56-0608 53-4276 52-0857 51-8037 49-9630 49 -91 73* 48-1222 46-3847 44 2712 43-4159 41-9670 39-7680 39-5791 38-4112 38 2760 36-0640 33-0691 33 1252 32-1120 30-9360 29-4608 29-4193 25-2745 4459-583 4450-947 4435-427 4427-650 4426-026 4415-519 4415 260 4405 168 4395-539 4384-005 4379-392 4371-648 4360-064 4359-078 4353-015 4352-317 4340 994 4325-962 4326 247 4321-238 4315-473 4308-313 4308-113 4288-450 604 967 444 666 038 523 304 597 184 420 608 293 300 370 260 246 430 230 20 22 24 93 16-65 29-11 15-62 149 472 537 864 046 939 202 257 594 '766 210 270 280 270 280 13.75 17-76 18-42 17-76 18-42 171 539 005 951 286 720 220 253 285 i5'60 17-25 20-14 295 077 155 685 818 994 965 807 855 455 '448 66* 330 270 300 230 370 330 21-81 17-87 19-89 15-30 24-64 22-01 652 074 086 312 784 732 340 290 354 23-30 19-90 24 28 336 004 006 634 330 370 22 70 25-53 7io 524 297 876 400 214 957 520 310 310 340 356 26-74 20-74 22-78 23-85 239 226 458 293 939 992 178 023 300 234 280 270 20-76 16-20 19 40 18-72 162 772 390 26-13 424 134 290 + 20-27 Weighted mean + 20 ' 26 tr -\C-TT V d Curvature . -16-77 - -10 - -50 Radial velocity . 2-91 REPORT OF THE CHIEF ASTRONOMER 463 SESSIONAL PAPER No. 25a r, BOOTIS 769. 1907. May 22. (r. M. T. 16 h 51 m Observed by J. S. PLASKETT. Measured by W. E. H. \KPER. Mean of Settings. r Computed Wave Length . ( 'orreeted Wave Lt-ngth . Normal Wave Length. Displacement in Revolutions. Velocity. Mean of Settings. J Computed Wave Length . Corrected Wave Length . Normal Wave Length . Displacement in Revolutions.^ Velocity. :? 72 -37 51 l.' ; 72-1407 3" 71-7151; m 71- 6651 12 : 6C-0739 2 08-5989 12 68-5477 12 ! 67 6870 11 66'5026 11 66-4065 12 03-3054 |H 63-2838 !l 60-3530 2 59-8426 m 59-2733 12 58 '4^74 4554-627 4553-084 4550-122 4549 777 4536-338 4529-180 4528-841 4523-161 4515-805 4514-789 4494-898 4494-762 4470-447 4473-304 4469 814 4465-024 507 -257 964 '594 006 '766 250 370 240 +16-47 24-38 16-00 2 ! 1 i H 2" 2 11 2 3 1.', 1 1 2 1 2 _' 57-5897 56-8622 52-1741 50-0535 49-9998 48-2070 48-1555 43 4978 42-0517 41-7560 41-3860 38-4841 38-3357 32-1922 30-9890 30--9K43 4459-591 4455-219 4427-666 4415-548 4415-244 4405 164 4404-87? 4379-372 4371-661 4370-074 4368 116 4352-949 4352-182 4321-209 4315 312 4315 192 644 272 720 598 304 962 420 293 340 310 300 305 22-91 20-89 20-31 20'70 255 107 965 807 290 300 i9'20 19-86 211 951 260 17-73 105 768 730 894 855 508 476 664 250 260 260 230 16-55 17-10 17-26 15-34 702 116 160 312 856 "840 390 260 320 26-75 17-85 21-95 481 337 214 957 270 .380 18-0* 25-46 246 292 408 006 992 178 240 300 230 16.54 20-76 + 15-92 0(52 '772 -290 19-48 Weighted mes V n .... n . . <- 19-46 -17-43 14 50 1907. May 23. G. M. T. '14 1 > 08> R . r, BOOTIS Vd Curvati adial velo< 774. ire itv . + 1-4 ER. JLE. Observed by W. E. HARI Measured by J. N. TRIBI Mean of , Settings Computed Wave Length. CoiTCi'ted \V.iM Length. Normal Wave Length. Displacement in Revolutions. Velocity. ti * Mean of Settings. Computed Wave Length. Corrected Wave Length. Normal Wave Length. Displacement in Revolutions. Velocity. | 73 S7'-'2 3-5307 U 72'!J89 V 56-7139 j 57-9013 1 57' 9293 1 I 52-5304 PS 4S-.H521 $ 49-1726 | 49-45*6 49-2138 i . 45-3018 i 45 3471 ; 43-1330 ! 42-5531 4871-911 4875-673 4861 -911 452S-932 4549 '900 4550-311 4455 '601 ! 4395-386 4400-502 4405-090 4401-162 4341-187 4340 964 4307-974 4299 503 l! 4 2 1 f ! ;; ; t 42-5701 40-6425 40-4252 39-8399 36-5802 36-1574 35-5747 35-2917 SS5-5345 30-0803 29-3427 28-9702 27-5532 26-7817 4299-750 4272-077 4269-004 4260-771 4216 114 4210-469 4202-733 4198-999 4202-202 4132-687 4123 660 4119-134 4102 111 4092-974 726 053 277 760 247 [ "293 17 23 20-56 803 527 276 + 17-03 747 102 640 897 107 105 7 53 7-47 119 865 766 962 353 603 23 26 40-65 733 999 161 494 272 505 17-51 36-07 982 162 908 138 074 424 5 04 28-87 767 212 555 40-29 234 218 078 844 ooo 626 390 218 452 23-38 15-94 33 13 948 ' -950 634 932 314 018 21-82 1-25 - Weighted mej Vn ... in ' + 21-29 3 3 3 -17'7 o - '2 25032 R V x c8 V Mean of Computed Wave H P ^ Mean of Computed Wave 83 cS 1.5 "I ^ Settings. Length. si so II lf> .2 a o 4 .- Settings. Length. D Q eg I* x e | "3 o Q'~ > fc Q 58'0640 4549 '549 1', 40-8102 4271-728 872 760 112 7'85 58-0817 4549 ' 873 001 766 235 + i5'46 2 37-6159 4227 '429 50 '2577 4415 '039 37 '5998 4227-211 331 904 427 30-27 50-2836 4415-459 595 293 302 20 54 1" 36-7625 4215-917 021 897 124 8-82 49 '6247 4404-812 1 35-4747 4198 795 907 403 505 35 99 49-6384 4405 032 216 951 "265 18-05 1 33-0716 4167'618 706 438 268 19-27 46'3206 4352-943 2 Sl'1734 4143 682 46-2767 4352 270 454 006 448 30-86 1 31-1972 4143-979 051 914 137 9-91 45-5212 4340 763 939 634 305 20-95 1 29-9036 4127 997 053 862 191 + 13-88 40 "8015 4271'605 2 28-0030 4104 992 " Weighted mean +18'15 V a . ... . . -18'04 Vd 21 Curvature - '28 Radial velocity. . . 0-3 1907. May 29. G. M. T. 16 h 46 n ?? BOOTIS 793. Observed by J. S. PLASKETT. Measured by W. E. HARPER. Mean of Settings. Computed Wave Length. y Normal Wave Length. Displacement in Revolutions. Velocity. s Mean of Settings. Computed Wave Length. Corrected Wave Length. OJ 1 Displacement in Revolutions. j T 61 ' 2267 4613'852 ., 47 ' 7600 4379-416 2 2 2 61 2151 60-7801 60-5522 59 '7843 4613 -P29 4605 266 4600-908 4586'340 755 437 076 465 997 524 290 440 552 + 18-76 28-51 35-76 i-* tO I- 1 !-* N- 47 0501 45 2664 44-2835 43-0857 436S-323 4340 948 4326-157 4308'409 307 954 174 '443 840 634 694 023 467 320 480 '420 32 M 22-08 33-2S 29 If 59 '6576 45f3 954 150 "796 354 23-08 2 43-0609 4308-044 2 o 57-8364 56 "6522 4550-173 4528 ' 720 308 766 542 35-72 ? 40-5687 39 '7598 4272-055 4260'611 090 '760 330 23'2t > 52 "7 172 4460'183 2 39-7727 4260-835 861 "546 '315 22 H 2 2 g 50-0340 49-3967 48 '7 702 4415 682 4405 432 4395-400 783 471 293 951 490 520 33-37 35-46 1 y 37-8163 36-5183 35-4705 4233 751 4216-158 4202-202 768 167 328 897 440 270 3111 + 19 15 2 48-8021 4395-909 896 286 610 41-66 1 Weighted mean V a -19-56 Vd -15 Curvature ... - "50 Radial velocity. -29 03 8-8 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 465 1907. May 31. G. M. T. 14 h 54 m BOOTIS 797. Observed by J. S. PLASKETT. Measured by C. R. WESTLAND. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 72-9660 2 43-0819 0711 0208 21-20 2 72-8399 72-4047 8829 0181 +26-26 2 2 40-5728 39-7707 5560 "7517 0301 '0249 29-86 24'50 2 57-8365 8410 0142 17-10 2 39-7551 2 57 ' 8055 li 37-3501 3227 0339 32'5l 2 50-0029 ? 36-5196 4893 0271 25'77 H l" 49-3909 48-7877 3937 '7855 0263 0215 28-72 23'53 H 2 35-4969 35-4641 4631 0355 33-40 2 48 '7722 14 31-6032 5560 '0151 13"65 1 47-0514 0483 0352 37-45 ? 30-1736 2 45-2777 2 27-3086 H 2" 45-2658 43-5481 2617 0230 23-56 H 2 26-7220 26-7084 6579 0296 +25-48 Weighted mean +25'50 V -20-10 V d -.. - -05 Curvature... - "28 Radial velocity. 5-1 1907. June 10. G. M. T. 14 h 10 m BOOTIS 812. Observed by J. S. PLASKETT. Measured by W. E. HARPER. o> > > 4 5 4J eg " > eS > Mean of Computed Wave *> hr ** "la be i 0? Q Mean of Computed Wave 85 *A *? j ^ tt I >> Settings. Length. g c 3 j d OJ ^J $ i s * a Mean of Computed Wave it *-3 >> Mean of Computed Wave H ^ S 5 Q >> Settings. Length. it 1 F o> - "Si s o Settings. Length. if as 2 "S. "5 c 4J |H S^ 1C S 4J o" 64 B a/ ^ Izj Q > j?; Q > 8 59-4917 4580-498 2 45-2755 4341 084 2 59-0511 4572-262 308 758 550 + 35-91 2 44-2785 4326-119 199 939 260 IS '00 ' 57-8496 4550-094 156 '766 390 25-70 2 43-5520 4315-347 448 178 '270 18'71 1 1 57-8233 4549-613 2 42 ' 1004 4294 152 56-6631 4528-612 1 40-5592 4272-120 270 '760 '510 35 '7" U 56-3594 4523'178 345 985 '360 23-80 2 39-7555 4260-816 947 527 420 29-53 1 ' 53-1004 4466 '54 5 2 39 7351 4260-530 2 50-9767 4430-966 138 '678 460 si-ii 36-4997 4216-283 323 897 426 30-12 2 50-0392 4415-661 824 354 470 31-96 !', 35-4821 4202'76-t 768 198 570 40 ' f>S 2 50-0050 4415-107 2 35-4386 4202-190 2 49-4000 4405-349 498- 908 590 40.18 1 34-6655 4192-048 038 678 360 25 '74 2 48 '7697 4395-275 . 1 32'7961 4167'952 '902 617 285 20*49 47 2771 4371-789 893 343 550 37 62 2 30-1393 4134'712 1: 47-1802 4370-281 387 807 520 35-56 1 29-9750 4132 694 592 212 380 27 : 4fl Weighted mean + L*.i'S'.i V a -24-4(1 V d , -11 Curvature... - '28 Radial velocity.. + 5-0 1907. June 27: G. M. T. 14 h 55 m BOOTIS 891. Observed by^ Measured by/ H HAKIER - f*""- * wt7 Mean of Settings . Corrected "Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings . Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 1 2 ) 14 2 ? 2 2 57-7980 57-7762 49-9624 49-3500 48-7547 43-7277 47-0142 45-2395 45-2339 43-5028 43-0515 42 0723 8200 0173 + 20-87 2 2 2 1 1 1 2 1 2 2 V 40-5817 39-7320 39-7102 37-3052 36-4711 35-4539 35-4170 31 503C> 30-1178 27-2449 26-6595 26-6400 5833 7845 0324 0300 32-2 29'6 3936 7987 0279 0160 30-55 17-41 3613 5275 5119 .0363 .0262 .0414 3E-5 25'4 39 54 0602 0391 4125 6300 0313 28-1 2809 0322 33 71 :::::;::: 1009 0377 38-52 | 7335 0272 + 24-13 Weighte V V c R-iHia (1 mean + 30-53 24-87 '17 28 i irvaturi? 4- fi'7 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 77 BOOTIS 918. 467 1907. JulyS. G. M. T. 15 h 09" Observed by J. S. PLASKETT. Measured by T. H. PARKER. Wt. Mean of Settings . Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings . Corrected Star Settings. Displace- ment in Revolutions. Velocity . 2 59 '8099 1 44-2898 2798 '0206 21.27 1 57 '8572 8620 0352 + 42-38 1 43-5460 1 56 6611 1 43-0888 0758 '0255 25'98 1 55-1526 '1576 0321 37-77 1 41-3060 H 54 ' 7393 1 40'5805 5615 0356 35-31 1 50 '0034 1 39 '7823 7613 '0264 25-97 1 50 '0300 0296 0205 22'55 1 37'9860 1 1 49-4064 49-1127 4034 0360 39 31 1 14 37-3568 36 5317 3308 5047 0480 0425 46-04 40 41 1 48 ' 8040 "8020 "0292 31-68 35-4581 li 48 '7675 1 35-2228 1928 0438 41-08 1 46 0327 45 ' 2824 0257 2744 0385 '0437 40-40 45 '62 1 1 31-8048 SO'9164 7713 0232 + 21 01 1 45 -2825 Weighted mean +34'45 V a -25-79 V d - '24 Curvature .... "28 Radial velocity + 8'1 1907. July 8. G. M. T. 15 h 09" r, BOOTIS 918.* Observed by J. S. PLASKETT. Measured by W. E. HARPER. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings. Settings. Revolutions. Settings. Settings. Revolutions. li 59-0510 2 44-3211 2820 0228 23-55 r 59 '0781 0634 '0227 + 27-74 2 43 '6749 2 57-8689 8520 0252 30-34 2 43-1211 . '0790 0327 33 32 .) 57 "8388 2 41-8827 '8380 1 56 8542 8352 '0244 29'04 2 41'3385 2 56-6862 2 40-6093 5590 0331 32 83 1 55-1704 1464 0212 24 72 2 39-8204 1694 0345 33 95 2 54 ' 0562 11 39 '7879 li 52-8790 8510 0206 23 40 2* 39-1058 0533 0370 36-11 2 59 4827 '4547 0399 45 "13 2 38 "0112 9 52-2770 2 37-3845 3295 0407 39 03 2 50-0586 0280 0179 19-69 2 36-5511 4940 0318 30-24 2 49 " 4332 "4012 "0350 38 "22 2 35 '4884 2 48'8006 1 35-5290 4706 0430 40-46 2 45 -3] 40 U 35-2561 1973 0483 + 45-06 2 45-3180 2800 0413 43-12 Weighted mean +33'11 V a -2580 Vd - -24 Curvature "28 *Check measurement. Radial velocity + 6'8 468 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 77 BOOTIS 950. 1907. July 18. Observed by J. N. TRIBBLE. G. M. T. 13 h 57 m Measured by W. E. HARPER. Wt. Mean of Settings . Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 1 14 l| 2 H 2 1* $ 2 4 59-7949 59-0552 57-8347 57-8138 53-0966 52-8357 52 4416 50-0253 49-3917 48-7944 48-7650 45 2671 45 2590 ? 5' 2 1 1 2 1 1 3 1 1 43-5484 43-0820 42-1019 40-5663 39 7395 39-7719 39-0430 37-3630 37 3251 36-5090 35-4418 35 4710 35-1990 5524 0852 0192 0451 19.68 45-95 0672 8427 0265 0160 +?2'36 19-26 5655 0396 39-28 8490 4546 0343 3997 8010 0186 039N 0241 0331 0282 2i 1- 46 01 26 51 36-14 30-79 7700 0385 "0351 0222 34.54 21-67 3195 5020 0307 0398 29-44 37-85 4595 1875 0319 0385 30-02 + 35 92. 2654 0267 27-87 Weighte< v a v d Cu Radial i mean 4 31-38 -25-61 - -20 - -28 rvature velocity. . . - 5'3 1907. July 18. G. M. T. 13 h 57" BOOTIS 950. ' Observed by J. N. TRIBBLE. Measured by T. H. PARKER. Mean Corrected Displace- Mean Corrected Displace- Wt of Star ment in Velocity. Wt. of Star ment in Velocity Settings. Settings. Revolutions. Settings. Settings. Revolutions. 1 59 8053 1 43-0955 0835 0332 33'82 1 59-0690 0730 '0323 + 39'43 1 42-1179 1 57-8528 8563 0295 35-51 H 40-5776 5621 0362 35.91 1 57-0777 OM)7 0139 16-58 39-7823 7653 0304 29 91 14 56 '6654 1 38-0089 9889 '0278 26-93 1 53-1105 1 37-9769 1 52-8502 8512 0-208 23-62 1 37-8012 7822 0177 17-06 1 52-4460 4470 0-322 36-41 1 36-5180 4960 0338 32 04 1 45'2830 1 35-4775 4535 0259 +24-37 1 43-5729 '5619 '0287 29'43 1 35 '4548 Weighted mean- . +29'23 V a -2561 V d - -20 Curvature ... - ' 28 *Check measurement. Radial velocity . + 3-1 REPORT OF THE CHIEF ASTRONOMER 469 SESSIONAL PAPER No. 25a 1907. Aug. 1 G. M. T. 13 h 39"> r, BOOTIS 972 Observed by I Measured by J Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity . Settings. Settings. Revolutions. 1 Settings' Settings. Revolutions. 2 59'8125 i 1 47-2717 2733 0315 33 55 1 59-0699 0660 -0253 + 30 89 1 47-1677 1693 0225 23 96 2 57-8529 8497 -0229 27-57 1 47-0555 0571 0409 43 56 2 57-8249 2 45-2721 2 56-6666 U 45-2731 2751 0364 38-00 1 56 3701 '3709 0347 41 05 ?! a 43-5334 1 55 1626 1642 0390 45-47 1 43-0770 0795 0332 33 90 2 54-0291 2 40-5588 5580 0321 31 84 1* 52-8504 8494 0190 21-58 H 39 7640 7620 0352 34 64 1 52'4609 4600 0455 5V12 2 39-7388 2 52-2516 2 37-9622 1 50-0488 0488 0387 42-57 2 37-3332 3284 0396 37-97 H 49-4090 4048 0386 42-57 2 36-5021 4960 0338 +32-14 2 48-7684 2 35-4334 Weighted mean +36'02 V a -24-14 V* - "24 Curvature... - '28 Radial velocity . 11-4 1907. Aug. 7. G. M. T. 13 h 58 E 77 BOOTIS 990. Observed by J. S. PLASKETT. Measured by W. E. HARPER. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings. Settings. Revolutions. Settings. Settings. Elev olutions 1 77-5311 3820 0765 + 34 73 2 68-8751 2 77'5065 14 68-0457 9557 0875 37'45 1 77-2249 0775 0838 37'88 2* 67 6516 5636 0768 32-87 li 75-4S40 3450 0687 30-91 2 64-6597 5717 0641 26-92 2 75'3861 2 61 4950 H 74-5448 4108 0755 33-75 1* 60-5500 5045 0777 31-62 2 73 1143 9873 0597 26-45 2 58-9771 9411 0833 33 57 2 72-8337 7101 0719 31 71 1 58-6538 6200 0878 35-38 3 72-1565 '0350 0677 29 79 2 56'4377 2 72'072l 1 50-0635 0820 0726 27 66 o 70-0758 9700 0879 38-15 11 48-1930 2266 0853 +32-07 2 69 ' 3246 2233 '0691 2)'78 2 46-3541 2 68-9702 8732 0867 37-37 Weighted mean +32'66 V a -23-09 Vrf : - -28 Curvature ... ' 28 Radial velocity + 9.0 470 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 77 BOOTIS 1231. 1908. Jan. 14. Observed by \ w F H , RPFR G. M. T. 22" CO-" Measured by/ W< ^ HARPEK - Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 1 2 ? 1 2 2 2 1* 2 $ M 57 8434 57-8277 54-7647 53-1290 52-8248 52-3986 52-2705 49-9963 49-3502 48-7851 48-7630 45-2867 45-2195 ? 2 2 2 14 2 2 1* 2 li l| 44-2401 41/3012 40-5147 39-7496 39-7099 39-0059 .37-9716 37-2765 36-4496 35-4474 35-4212 35-1325 2266 0326 33-67 8047 0221 26-61 5000 0209 25-69 8048 3790 0256 0358 29-08 40-49 6959 9925 0309 0238 30'40 23 23 9788 3340 0313 0334 34-43 36-47 2630 4350 0258 0272 24 '74 25-87 7470 0258 28-00 4043 1150 0233 0340 2192 -31-72 2060 0327 34-14 Weihted mean - 29 ' 76 +26-58 Va ... + -12 Curvatare . . "28 Iglltl Va Cur Radial velocity. - 33 .BOOTIS 1231.* 1908. Jan. 14. Observed by W. E. HARPER. G. M. T. 22 h 00 m Measured by T. H. PARKER. Wt. Mean of Settings . Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity 2 1 1 1 1 f 1 2 1 1 1 1 1 59-8174 57-8144 56-6735 53-1182 52-8153 52-3882 52-2605 50-0076 49-9827 49 3633 49-3360 49-1028 48-7675 48-7445 1 1 1 1 2 14 1 2 1 1 1 1 44-2521 41-2816 40-4982 39-7312 39-6870 37-9558 37-2517 36-4308 35-4251 35-3991 30-8692 30.8499 29 9064 8084 0182 -21-91 5032 0227 22-51 8133 3872 0171 0276 19-42 31-21 6915 0353 34 73 2567 .4358 0321 0264 33-66 25-00 9847 0254 27-94 4041 0264 24-8* 3390 0272 29-70 8543 0213 -19-12 7485 0155 16-81 Weighted mean . -25-62 . -4 -26'5& - -12 V, Curvatur Radial veloci ; - -28 tv. .. + o-e "Check measurement. REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 77 BOOTIS 1204. 471 i908. Jan. 27. Observed by l^r v TT. n G. M. T. 20" 12" Measured by/ W ' R HARPER - Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions . Velocity. Wt. Mean of Settings . Corrected Star Settings. Displace- ment in Revolutions. Velocity . 2 o 2 2 2 2 14 3" 2 2 2 o 2 o 76-7049 76-3139 74-9780 74 9412 74-0085 73 3760 72-6176 71-7327 71 6719 69-0070 68-8730 68-5172 68-5312 r.7'6069 64-2811 61-3235 2 2 2 2 2 2 2 1 2 2 2 2 2 2 2 2 60-2453 59-7232 58-3645 57-4642 56-3435 56 7436 56-0215 50-9975 49-9284 48-0797 46-4398 46-3377 38-2531 36-2270 36-0357 33-1311 2668 7437 3830 4818 0714 0627 0767 0701 29.34 25-11 31-14 28-32 3760 0487 -22 25 9966 0615 0686 0691 31 07 31-16 7596 0370 0669 0559 26-90 22-36 6656 O'JOO 30-77 7194 6495 fl30 5572 0628 0647 0794 0705 27'88 28-27 34-46 30-60 9324 0787 0677 26 "GO 0806 30-63 3310 2267 0839 0794 31-46 28 34 (1434 '0735 3091 '0754 31-75 31-82 0027 0940 0878 30'90 0779 -26-87 Weigti Rad ted mean - 29.00 28 V a +25-27 + -16 V d Curvature ial velocit\ - 3'8 IOCS. Jan. 29. G. M. T. 21 h 14 m r, BOOTIS 1307. Observed by J. S. PLASKETT. Measured by C. R. WEST-LAND. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings. Settings. Revolutions Settings. Settings. Revolutions. o 76 755(3 2 59-7720 7402 0662 27-12 H 76-3539 3649 0598 -27 37 2 58-4380 4030 0567 23-02 2 75-0276 2 57-5179 4802 0715 28-86 74-9901 9980 0660 29-92 2 56-8023 7628 -0637 25-59 2 74 ' 0588 '0640 '0666 30 02 2 56 3977 2 73'4219 1 56-0711 0300 0629 25-15 2 72 ' 6605 ' 66'?0 "0726 32 '41 2 50'0571 3 71-7218 7208 0614 27-24 2 49-9803 9258 0851 32 70 2 69-6614 6552 0590 25-81 2 48-1479 0864 0685 26 01 2 68 ' 9241 '**! j'l "0765 33-31 o 46 '4998 3 68-5710 5620 0657 28-53 2 46-4076 3415 0731 27-56 2 68'6280 2 38-3121 2251 0810 28-88 2 fi7 fin49 (>497 "0742 32'03 2 36'2864 2 64-3451 3251 Of94 25-08 2 36 1037 0107 0798 28-06 2 61 3704 2 33-1978 0938 0781 -26 96 11 AO-9Q3Q -9fiS4 0748 30 '75 2 33 '2792 L -2 Weighted mean -2832 V a +24-95 Va + "13 Curvature... - "28 Radial velocity. - 3-5 472 Feb. 17. 1908. G. M. T. 22 h 30 m DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 r, BOOTIS 1332. Observed by .T. S. PLASKETT. Measured by C. R. WESTLANH. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 2 2 2 2 2 2 3 2 2 3 2 3 2 2 2 2 76-7212 76-3188 74-9946 74-9565 74-0249 73-3885 72-6378 71-6874 69-6200 68-8936 68-5431 68-5930 67-6210 64-2952 61-3281 60-2510 59-7464 2 2 2 2 1 2 2 2 2 2 2 ' 2 2 2 2 2 58 3842 57-4824 56-7485 56-3452 56-0291 53-4001 49-0003 49-9357 48-0881 46-4381 46-3480 38-2430 36-2164 36-0427 33-1294 33-2010 3982 4954 7600 0615 0565 0665 24-97 22-80 26-71 3628 0619 -28-33 9982 0649 0658 0657 29-83 29-61 0393 4061 0536 0624 21-43 24-52 6756 7236 6528 9251 5741 0590 0586 0614 0673 0536 21-34 26-00 26-86 29'SO 23-18 9359 0853 0750 0696 28-82 26-43 3422 2240 0727 0821 27-30 29'28 6505 3192 0664 0653 28-66 27-57 0202 1019 0703 0700 24'72 -24-16 2682 7629 0700 0435 28-78 17-82 Weigl V V C Radia ited mean . 25 21 28 + 20-45 + -12 4 urvature 1 velocity . . . - 5-2 1908. Feb. 24. G. M. T. 19 h 06" BOOTIS 1357. Observed by) -* Jl_ f Measured byj Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity Settings. Settings. Revolutions. Settings. Settings. Revolutions. 2 76-7176 : 67-6130 6450 0719 30-99 1 76-3250 3710 0537 -24-59 i 63 2135 2395 0700 29 33 i 74-9671 '0101 "0539 24 42 2 61-3207 0 0377 1152 0263 0154 -11-92 6 94 2 2 2 57-4580 56-7254 56-2921 5231 7917 0288 0318 11-62 13-98 2 3 72-6643 71 ' 70'J7 7044 '7522 0302 "0300 13 48 13 '31 1 2 56-0050 49 9236 0732 0197 7-88 2 2 2 68 9128 68-5557 68'576J 9623 6061 0301 0216 13 10 9-38 1 2 2 49-8982 48-0465 46-3500 9763 1272 0346 0321 13-20 12-19 2 2 67-6457 61-2856 6970 0199 9-32 2 3 46-3083 38-1702 3908 2679 0241 0382 9 05 -13-62 2 60 "2494 3100 i (28 11 59 2 36-0923 2 59-7264 "G^ft |O|O 018C 7 62 Weighted mean ..................... - 10 94 + 3-98 *Check measurement. IgD Va Curvature. . Radial velocity.. "28 - 7-5 474 DEPARTMENT OF THE INTERIOR 1908. March 30. G. M. T. 21 h 52'" 7? BOOTIS 1440. 1 9-10 EDWARD VII., A. -510 Observed by W. E. HAKPEE. Measured by T. H. PARKER. Wt. Mean of Settings . , Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings . Corrected Star Settings. Displace- ment in Revolutions : | VelocityJ 1 76-7922 1 59.7825 '7820 0244 10.00 ! 1 76 '4392 75-0585 4142 0105 -4'80 1 1 58-4374 57-5302 4384 5322 0213 .0197 8'64 1 1 2 75-0715 73-4509 0465 0175 7-92 1 1 56-7981 56-3536 8011 '0154 6'19 ; 1 72-7325 7074 '0272 12 is 2 49'9915 2 1 1 71-7755 68-9752 68-6257 7505 9542 6047 0317 0382 '0230 14-07 16-62 9'98 1 1 2 49-9582 48 1122 46 4180 9712 1272 0289 0321 11 '09 ij 2 68-6416 1 46-3655 3845 0304 1 1 67-7025 61-3480 6945 0224 .9-67 1 1 38-2275 36-1572 2595 0466 1 60-3231 3211 0171 7'02 Weighted mean - 10'39 Vfl +3-98 Vd - '25 Curvature. . . - 28 "Check measurement. Radial velocity . - 6'9 1908. May 4. G. M. T. 18" 13" BOOTIS 1513. Observed by| w E HARPER. Measured by/ Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity Settings. Settings. Revolutions. Settings. Settings. Revolutions. 2 75-1160 2 63 ' 3747 2 74-2116 2076 0087 + 3'91 1 63-3747 3635 00(51 2 . 2 73-4946 1 60-3917 3785 0109 4'4" 2 72-8120 8070 0080 3'55 1 59-8668 8533 0189 '"I 1 72 '5446 '5394 2 58 "8243 ' 2 72-2822 2770 0131 5-82 2 58v5330 5188 0112 - M 2 71-8622 8567 0118 5-63 1 56-8700 8540 0081 3 '24 li 69 '7922 '7857 '0155 6 '76 2 56-3934 r 69-0562 "0492 2 53-9788 i 68-7040 6967 0159 6'92 1 52-1672 1482 0164 6 -3ft 2 68-6835 1 48'1835 1620 0087 -f 3'30 1 67 '7903 '7823 0150 6'46 9 46 "4436 1 65-5445 5350 0056 2.37 Weighted mean + 4 ' 91 Curvature . Radial velocity. . . . -11-19 - 17 - -28 - (5'7 REPORT OF THE CHIEF ASTRONOMER :E5VONAL PAPER No. 25a BOOTIS 1557. 475 May 23. Observed by J. S. PLASKETT. (T. M. T. 16* 00 m Measured by T. H. PARKKK. V. Mt an of Settings. Corrected Star Settings . Displace- ment in Revolutions. Velocity. Wt. Mean of Settings . Corrected Star Settings . Displace- ment in Revolutions. Velocity. 1 1 1 2 2 1 X 7iV9548 7t! 9700 76-6302 75-2687 7.V 2128 73-5876 72-9026 71-9679 71-9354 69-1677 '< 7609 1 2 1 1 1 2 1 I 4 2 68-2353 67-4948 63-4283 59-9277 59-3672 56-4245 52-7616 50-0213 48-1823 46-4392 46-4258 2063 4461 0138 0085 5'93 3'63 9334 5937 2326 0152 0200 0273 + 6-93 9-10 12 31 8962 3358 0339 0362 13 79 14-69 8696 9359 0064 0303 2'84 13-36 7366 0308 11-98 1643 4238 0168 0315 6-35 + 11-74 1285 0283 12-25 We'g'it RaH:';: r, BO OTIS 155. 1903. May 25. G. M. T. 15 h 58 ra td mean + 96 17-97 10 '28 8-7 EtKEB. Vd - Curvatu il velocity re. . . X \ Observed by \ TT p . Measured by / ' ' \.r. Mean Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 1 1 ] i 76*9679 77 3242 7'-6597 76-4693 75-2271 74 3368 73 6031 72-3932 71-9847 71-3184 - 69-1583 2 2 2 2 1 2 1 2 2 2 2 2 68'79t5 68-7714 67-8874 64-5208 63-4552 63-4326 61-4657 60-4492 59 9312 59-3753 58 : 8903 56-4272 8090 0225 9-69 3499 '0444 6853 '0371 4923 -0189 .+20-24 16-84 8-58 9004 5278 4606 0322 0202 0371 13-78 8-46 15 43 3568 0215 9 61 4657 4482 9297 3723 8853 0300 0214 0394 0464 0275 12-30 8-73 15-90 18-83 + 11-08 4112 -0210 0027 '0354 9-26 15-57 9123 -0302 1728 -0186 13-10 8-03 Weighted mean +12'38 Curvature . Radial velocity . . , -18-59 - -10 - -28 - 6-6 476 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 1908. May 23. G. M. T. 15 h 5 77 BOOTIS 1553. < Observed by T. H. PARKER. Measured by W. E. HARPER. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity, 2 76-8899 f) 68 '7225 8120 0255 10 99 1 77 -2379 3119 '0364 + 16-60 2 68-6957 2 1 2 76-5803 76-3967 75-1498 6833 4997 0351 0263 15-93 11-91 2 2 2 67-8170 64-4485 63-3766 9050 5294 4560 0368 0219 0325 15-73 9-24 13-52 3 74 '2572 '3557 0202 9 03 2 63 '3594 2 73-5255 1 61-3866 4610 0253 10-37 2 2 2 72-3153 71-9030 71-8607 4103 9973 0201 0300 8-84 13 20 2 2 1 60-3764 59-8471 59-2900 4489 9186 3600 0221 0283 0341 9-02 H'49 13-78 2 71-2438 2 58-8184 8874 0296 + 11-% 2 69 "8265 '9175 0354 15 "36 2 56 '3496 2 69-0868 1768 0226 9'76 Weighted mean + 12 " 16 V -18-59 V:> 17 425 -390 035 452 398 054 044 + 14-56; Weighted mean 1520 Standard . . + 19-15 + '38 19-53 -25-71 - -24 Radial velocity. - 6-4 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 479 1908, Aug. 19. G. M. T. I3 h 18 BOOTIS 1792 Observed by W. E. HARPER. Measured by T. H. PARKER. Settings I. Settings II. 1 )iffpl*prPA T\* AT n n nn in in (Mean legion. , Star Comparison. Revolutions. Star Comparison Revolutions. Difference Velocity. 5 '802 817 015 718 60 028 022 + 10-86 6 "812 824 012 697 673 024 018 8'56 i 815 834 019 710 671 039 029 13 31 8 829 846 017 693 670 023 026 11-51 9 828 841 013 681 660 021 025 10-72 10 831 860 .029 685 654 031 030 12-45 11 837 865 028 682 644 038 033 13-23 12 842 868 026 687 654 033 029 11 25 13 853 885 042 668 640 028 035 13-16 14 865 895 030 660 619 041 036 13-10 15 864 908 039 636 600 036 037 13 02 16 876 909 033 637 591 046 039 +13-29 Weighted mean +12'04 1519 Standard.. . + '41 Vd . Radial velocity . -20 04 - '28 - 79 1008. Sept. 7.* G. M. T. 12 h 57" 77 BOOTIS 1867. Observed by J. S. PLASKKTT. Measured by J. B. CANNON. Mean Corrected Displace- Mean Corrected Displace- \Vt. of Settings . Star Settings. ment in Revolutions. Velocity. Wt. of Settings . Star Settings. ment in Revolutions. Veloci ty . 2 76 9031 2 71'8856 H 77-2356 2508 0215 + 9.80 1 68-7611 7763 0428 18-49 1$ 76 6039 6189 0452 20'61 2 68 7171 1 75-8642 8777 0405 18-35 1 67-8216 . 8366 0188 8'06 u 72 '8396 8798 0166 7'37 ., 63'3916 ll 72 5992 6116 0369 16-35 1 60-4216 4276 0302 12-35 2 71-9211 .9371 0315 13-89 i 59 3391 3441 0545 22-13 Weighted mean +14'18 V a -13-88 Vd - '30 Curvature - '28 Radial velocity . - 0'3 25o33 480 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 1909. Jan. 7. G. M. T. 23" 23'" 77 BOOTIS 2115. Observed by J. S. PLASKBTT. Measured by W. E. HAKPER. Mean Corrected Displace- Mean Corrected . Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings . Settings. Revolutions. Settings Settings. Revolutions. 2 76 6775 2 69-3445 3612 0260 11 39 2 76-6430 6575 0344 -15-82 2 68-8810 9002 0381 16-65 2 76'3060 3200 0301 13-79 A 68-5537 2 74 9547 2 68-5247 5245 0502 21-80 1 74-9365 9467 0464 21 ii 2 67-6056 6244 0421 -18-24 1 74-0052 0152 0471 21 29 2 67-2315 2501 0393 17 02 2 73-7510 7610 0413 18-63 2 65-3890 4052 0359 15 30 2 73-3481 1 64-2927 3075 "0360 15 30 2 72'6167 6277 0425 19'08 2 63 '2724 2 72-3162 3279 0560 25-09 2 63-2091 2230 0486 20-41 2 71-6667 6810 0394 17 53 2 58-7025 7188 0387 -15-79 2 71-0812 2 58-7427 2 69-6012 6173 0409 17-91 Weighted mean i - 17 "88 V a +26-69 V 30 1 " 17 BOOTIS 2283. Observed by ) T Measured by / J ' Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- . ment in Revolutions. Velocity. 2 76'7061 1 61-0771 1522 '0283 11 '70 i 1 i 76-6704 74-9769 74-0486 7317 0382 1100 0357 0258 0206 -16-38 11'70 9-28 1 1 2 59-6981 56 7141 56-2824 7740 7913 0324 0342 13 27 13 74 1 9 73 0121 73 3628 0736 0474 21 21 52-9986 51-6967 0808 "7801 0450 0303 17-53 11 '78 1 1 72-1104 71-6891 69-6231 1739 7546 6925 0272 0276 0217 12-10 12-24 9-49 if l| 2 49-8821 48-0301 46 3428 9680 1171 0321 0378 12 34 14 35 2 68-5548 1 46'2721 3617 0532 19'97 1 68-5298 6012 0265 11 51 2 33 0633 2 * 67 6224 63-2498 6945 0224 9-67 , 31 5776 30-8284 6899 9422 0444 '0517 15-19 17 '61 1 63-1931 2674 0421 17-65 j 26-4908 6107 0496 -16 44 Weighted mean -13'98 V a Vd Curvature... - '28 + 20 25 + '04 Radial velocity + 6'0 1909. March 20. 77 BOOTIS 2396. Observed by J. S. PLASKETT. Measured by J. B. CANNON. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Vf locity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 77 ' 1341 1 68-6049 6109 0168 7'29 1 A 76-7516 76 4234 7465 '4178 0209 '0060 -9 59 2'75 1 2 67-6992 61-3222 7072 0097 4-19 r I 75 0522 74-1209 73-4249 0491 1191 . -0149 0115 6 75 5-19 1 1 1 . 60-3016 59-7754 58-4149 3269 8027 4462 0113 0037 0135 4-64 1 51 5-48 i 72 ' 7076 "7079 0267 11 -91 2 49-9442 , 72-4306 71-7664 4318 '7688 0157 0134 7-00 5-95 1 2 49-9466 30-9059 0041 0068 2-61 2 71-1534 1 30-8756 9795 0144 -4-91 1 69-7034 7074 0068 2-97 Weighted mean V a. . 5 59 Vd ....... Curvature,. 8-52 14 - -28 Radial velocity . + 2.8 482 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 OBSERVING RECORD AND DETAILED MEASURES OF a CORONA BOREALIS. P.-PLASKETT. RECORD OF SPECTROGRAMS. P 1 . -PARKEF. H. HARPER. C. CANNON. T. THIBBLE. STAB. t -3 "o 1 i 8 O Plate. Date. 0) I & *rK =3 T3 1 1 3 n Hour Angle at end. TEMPER." Centigi Room. LTURE. ade. Prism Box. -5 S % . II .. Settings. Length. fl "S-e J Settings. Length. c a g 3~ o-2 5' 3 Z 6" o< Q 3 73'2093 4870-229 g 27 7347 4105-312 72-8135 4800-908 2-107 1-527 5PO +35-78 1A 27 5259 4102-815 700 1 890 810 +59-21 63-6051 4661-138 3 27 2873 4099-970 48-7331 4395-316 15 64 3970-820 '797 177 620 + 47-00 45-2535 4341-252 3~ 15-4860 3969-232 45-2502 4341-201 114 0-634 480 + 33-12 Weighted mean +41'68 V a - 9-22 Va + -10 Curvature... - '28 Radial velocity. + 32'3 REPORT OF THE CHIEF ASTRONOMER 485 SESSIONAL PAPER No. 25a 1907. May 29. G. M. T. 18>>05" a CORON/E BOREALIS, 794. Observed by J. S. PLASKETT. Measured by W. E. HARPER. B c c3 , Mean of Computed Wave J3 ^3 "3 "So S if >, ^ Settings . Length . U Is w Settings . Length . jjjf 1 B r * SJ r5 ("* S 1 c | ^ o fc S - 6 ^ S >* 2 72-8775 4862-407 407 1-527 880 +59-30 1 27-5506 4102-369 360 1-890 470 +34-36 T 63 6559 4661 600 ,', 12-111- 3934-713 795 3 '825 .970 + 74-01 3 45-3234 4341 403 388 0-634 754 + 52-02 S 11-6613 3930-276 45'3085 4341 ' 177 27 ' 7905 4105 ' 235 .. . Weighted mean . +53" 45 V a - 9-22 Va - -14 Curvature ... . - "28 Radial velocity +43'i 1907. May 31. G. M. T. 17" 18" a CORONA BOREALIS, 800. Observed by J. S. PLASKETT. Measured by W. E. HARPER. 5 m "> jj < C c3 c a o ^J S-a j^ i C 'r^ ! Mean of Settings. Computed Wave Length . I! It U -s ? ^ o g fa f -J Mean of Settings. Computed Wave Length . "S3 g be 03 ~ C" if g3 isplaceme in revolu | 1 o O > > ^ q *> I 73-2965 4871-490 ]\ 45 3314 4341-634 i-ooo 0-634 366 +25-25 72'8966 4862 ' 058 2'021 1'527 494 J -30'48 f 45 ' 3203 4341 ' 463 1', 63-6950 4662-143 Weighted mean +28'24 V a - 9-87 Vd - -09 Curvature "28 Radial velocity.. + 18-00 486 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 a CORONJE BOREALIS, 800*. 1907. May 31. Observed by J. S. PLASKKTT. G. M. T. 17 h 18 Measured by W. E. HARPER. 1 4 ,.j > 0> o Mean of Computed Wave t ^ II Mean of Computed Wave | f - > ""5 11 Settings. Length. n ~ E % "3- c | Settings. Length. 2 If i= I i o O * a o "" o fc 5 > 2 73-1662 4870-711 . 53-9228 4482 746 156 400 756 + [50-57] 72-7643 4861-253 '993 527 366 + 22-58 |I 45 ' 1975 4341 903 53 9370 4482-990 2 45-1921 4341-822 084 634 450 +31-05 Weighted mean +26'82 V a - 9-87 V d ..., - -09 Curvature.... "28 *Check measurement. Radial velocity +16"G a CORONA BOREALIP, 1907. June 8. Observed bv J. S. PLASKKTT. G. M. T. 16 h 28 m Measured by W. E. HARPER. 2. 3 H Mean of Settings. Computed Wave Length. Corrected wave length. Normal wave length. Displacement in revolutions. Velocity. Mean of Settings. Computed Wave Length. Corrected wave length. Normal wave length. Displacement in revolutions. Velocity. 73-6301 73-2099 72-7779 54 7247 53 9597 4880-622 4870-635 4860-446 4494 835 4481-558 H 2 a 53-2825 45-2977 45-2356 27-4985 27 3464 4459-560 4341 340 4340 399 4101 ' 465 4099-648 117 527 410 -25 30 224 740 634 890 410 150 -28-29 -10-97 400 400 ooo [O'OO] Weighted v \ C lean -24 63 -12 26 - -07 - -28 p ?d urvature . . Radial velocity . 37 2 REPORT OF THE CHIEF ASTRONOMER 487 SESSIONAL PAPER No. 25a a CORON^E BOREALIS, 813. 1907. June 10. Observed by J. S. PLASKETT. G. M. T. 15 h 23'" Measured by W. E. HARPER. o sj e > c3 o 0*9 02 e* *^ Mean of Computed Wave > T3 ^ N * Is 11 Mean of Computed Wave P. g 3-' if ^ Settings. Length. C |P 1 SP 'S Settings. Length. if 11 'g y> IJ S 3 *> c S fc S S * O fe G > ^ O ^ Q > 1 72 "9500 4864-729 U 45-2570 4340 581 584 634 050 - 3-45 li 72 7916 4860-995 047 527 480 -29-62 r 27-4836 4101-565 565 890 325 -23 76 1 54-0328 4482-605 i H'9745 3933-225 505 825 320 -23'52 53-9933 4481"933 720 '400 '320 + [21 '401 s- 11 '6547 3930'072 Weighted mean ... - 19 ' 99 V a -12-82 V/ '00 C /urvature - '28 Radial velocity -33'1 1907. June 10. G. M. T. 15 h 23 a CORONA BOREALIS, 813 Observed by J. S. PLASKETT. Measured by W. E. HARPER. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Mean of Settings . Corrected Star Settings. Displace- ment in Revolutions. Velocitv. 1 73-0019 1 27 4611 3746 0380 -33-00 1 72-8452 8543 0105 -15'23 2 27-3334 1 72-4360 1 11 '9831 '8494 0020 - 1 50 2 45-2862 11 '6415 45-2550 2404 0017 + 1-77 Weighted mean ... .............. -11'33 V ........................ -12-82 Check measurement. Curvature . Radial velocity . . '28 - 23 4 1907. June 11. G. M. T. 17 h 40" DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 a CORONAS BOREALIS, 830. 4J Mean of Settings . Corrected Star Settings. Displace- ment in Revolutions- Velocity. Mean of Settings . Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 73-0400 1 27 '5388 4018 0108 - 9'37 i 72-9005 '8714 0066 + 9'57 2 27 '3833 2 72-4707 15-6378 4462 0271 -20-97 2 45 '3505 2 15-5903 45-2971 2202 0177 -19-31 Weighted mean - 12'59 V a -13-12 Vd - '14 Curvature... - '28 Radial velocity . - 26-1 a CORONA BOREALIS, 837 (a). 1907. June 12. Observed by J. S. PLASKETT. G. M. T. 17 h 36 m Measured by W. E. HARPER. 1 > 6 3-2 B *3 . 1 eS 4 si Mean Computed "04= ir 11 Mtan Computed "Oja a S'o of Settings. Wave Length . II S _, *3 "3 jo S? > 1 of Settings. Length . If It f* 'o. _. ^ I 4J *^ Sw oo. B 13 8M Qh? a S F" o fc Q F D & 5 > 9 73-2575 4871-377 U 53 '2836 4469 ' 109 260 1'400 140 - 9 37 > 72-9590 4864 316 2 45 2743 4341 034 1 72-7939 4860-427 027 527 500 _ 3Q-85 2 45-2468 4340 618 744 634 110 + 7-5? 14 54 7243 4494-565 1 27-4500 4101-723 700 890 190 -13 40 r 54-0416 4482 ' 729 "880 T400 1480 + [99-bi] 2 27 '2997 4099'937 ti 53-9476 4484-109 Weighted mean - 7 "84 V fl -13-39 V ^ CJ 11 11 -5 "5 0^ ~ '3 -3 ^ - - SM- * .S "3 F O to 5 ?- H > '2 73 3641 4871 ' 496 U 45 3637 4340 923 834 200 + 13-80 I 1 . 73-0748 4864'652 r 27 '5769 4102'126 780 ! '890 '110 - 8'74 1 72 9262 4861 ' 152 '417 527 080 - 4'90 27-4205 4100-265 - 45 3955 4341 251 I ' i ] Weighted mean . + 2 "22 V a -13-39 . - '15 Curvature 28 Radial velocity . . , - 11 6 o CORON^E BOREALIS, 845. 1907. June 13. G. M. T. 16 h 32 m Observed by ) w F VTARPET? Measured by / Wl *" HAR1 > 1 m :J > | , Mean Computed g m C'-E s- 5 Mean Computed 1 II of Settings. Wave Length. II l! |i | of Settings. Wave Length. || 1* g f O Q 1 m C 1 Kr-i O to . ^ Q 6" to 3"" 2 73' 5911 4875 434 ', 30-3756 4135 '609 374 2 73-1412 4864'776 30-3142 4134-852 1 73 0219 4861-964 817 527 290 + 17-89 1 27-6096 4102-126 1-921 890 031 + 2-27 2 45 4418 4341-360 a 27-4418 4100 132 H 45 4224 4341 -06S 0-868 634 23.4 + 16-14 Weighted mean +12'68 V- -13-65 1 T* . 28 Curvature Radial velocity . . - 1-4 490 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 191O a CORONJE BOREALIS, 850 (a). 1907. June 14. Observed by J. S. PLASKETT. G. M. T. 16 h 39 m Measured by W. E. HARPER. 2 2 1 H Mean of Settings. Computed Wave Length. Corrected wave length. Normal wave length. Displacement in revolutions. Velocity. H Mean of Settings. Computed Wave Length. Corrected wave length. Normal wave length. Displacement in revolutions. Velocity. 73-4113 72-9635 72-8279 54 3973 4875-633 4865-037 4861-845 4489-656 53-9875 53-2781 45-2668 45-2482 4482-586 4470-405 4341-590 434 I' 307 1-046 400 646 + [43'i!2; 747 527 220 + 13-57 0-879 634 245 + 16-90 Weighted : i ( Radial nean . +15-79 2 2 8 f a -13 { 1 - -^ fd Curvature velocity . . + 1-5 a CORONJE BOREALIS, 850 (b). 1907. June 14. Observed by J. S. PLASKETT. G. M. T. 16 h 52 m Measured by W. E. HARPER. *i Mean of Settings. Computed Wave Length. Corrected wave length. Normal wave length. Displacement in revolutions. Velocity. Mean of Settings. Computed Wave Length. Corrected wave length. Normal wave length. Displacement in revolutions. f H 2 73 4199 72 9631 72-8446 45-2666 4875-835 4865-169 4862-238 4341 587 1 2 45-2684 27-4757 27-2770 4341-613 4102-322 4099-954 188 2-290 634 1-890 "554 400 + 38-23 + 29-24 1-997 527 470 + 29-00 Weighted n i < lean +5 3-68 v a -13-92 - -12 - '28 V d Curvature. Radial velocity +19'4 REPORT OF TEE CHIEF ASTRONOMER 491 SESSIONAL PAPER No. 25a a CORONA BOREALIS. 861 (a). 1907. June 20. Observed by\ w F HARPFR G. M. T. 16 h 05 m Measured by/ ' c3 ~ cS 4* O ^ 1 fl *r? t^ -'~ Mean of Computed Wave -f Kr, OJ p If >, Mean of Computed Wave |5 3 tc || ^ Settings. Length. |g sg 1 "a; ^ Settings. Length . P c a g ^ g-g 8 " O S > ^ O !5 S 73 '27 60 4871 '450 U 45-2526 4341 493 72 9905 4864 '720 t| 45 '2364 4341-249 0'918 0'634 '284 -r!9'60 72-8861 4862-267 2 467 1-527 940 + 58-00 1 27 4436 4102 363 2-320 1-890 430 + 31 43 54-0070 4482 '788 9 '495 1'400 1 095 + [73.25" 27-2416 4099-960 53-2695 4470 164 Weighted meati. . . + 33 . 95 V,....: -15-42 Vd - '11 Curvature '28 Radial velocity + 17 ' 1 a CORONA BOREALIS, 869 (a). 1907. June 21. Observed by J. S. PLA&KETT. G. M. T. 15 h 10 m Measured by W. E. HARPKR. 1 1 Mean Corrected Displace- Mean Corrected Displace- of Star ment in Velocity. of Star ment in Velocity. Settings . Settings. Revolutions. Settings. Settings. Revolutions. & i* 2 73-4538 1 53-1220 H 72 9987 2 45 '2828 72-8723 8833 6185 + 26-84 2 45-2626 2574 0187 + 19-52 1 72 4343 1 27 '4687 4329 0203 + 17'62 1* 54-7447 2 27 '2824 i 54-0017 9962 0264 +[30-39] Weighted mean +20'J V a -15-65 Vd - '05 Curvature ... - ' 2? Radial velocity. + 4'9 492 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 a CORON^E BORE ALTS. 8C9 (b). 1907. June 21. G. M. T. 15 h 42' Observed by J. S. PLASKKTT. Measured by W. E. HABPKR. Mean Corrected Displace- Mean Corrected Displace- of Star ment in Velocity . of Star ment in Velocity. Settings . Settings. Revolutions. Settings . Settings. Revolutions. j 2 73-4265 53-0887 14 72-9753 2 45 '2563 72-8572 8940 0292 + 42-37 2 45-2497 2670 0283 + 29-53 1 72 4075 i 27 ' 4248 4145 0019 + 1 65 2 54 7245 2 27 ' 2569 1 54-0007 0197 0499 + [57-42] Weighted mean +29'22 V a -15-66 V d -07 Curvature "28 Radial velocity +132 a. CORONA BOREALIS, 880. 1907. June 25. G. M. T. 15 h 43" Observed by j w E HABPKR . Measured byj Mean Corrected Displace- Mean Corrected Displace- of Star ment in Velocity. of Star ment in Velocity. Settings . Settings. Revolutions. Settings Settings. Revolutions. J * . 2 49-3450 1 27-4294 4144 0018 + 1 50 2 45'1892 2092 0295 -30-80 1 27 "2616 2 44-2398 Weighted mean . . - 24 ' 34 V a -16-56 Vd 10 Curvature - ' 28 Radial velocity . - 41 3 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 493 a CORON/E BOREALIS, 888. 1907. June 26. G. M. T. 15 h 01" Observed by J. S. PLASKETT. Measured by W. E. HARPER. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings. Settings. Revolutions. Settings. Settings. Revolutions. 1 48 '7894 J 27-5130 5033 0168 + 13-57 2 45 '2958 '2794 '0307 + 32'14 27'3316 2 45'2880 Weighted mean V ffl + 28-42 Curvature . -18-76 05 - "28 Radial velocity +11'3 a CORONA BOREALIS, 892 (a). 1907. June 27. G. M. T. 15 h 25'" Observed by \ w F TT ARPI! , R Measured by/ W ' *" UARPEB - Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings. Settings. Revolutions. Settings. Settings. Revolutions. 2 73 '9825 2 45 2750 1 72 8545 8822 0174 + 25 20 | 45-2277 2363 0124 -12-98 2 72-4160 2 57'8430 8237 0190 + (22-91)* 54 0205 li 57-8172 1 53-9655 9603 0037 + [4'27] "Not used. Weighted mean +12'47 V -16-98 Yd -09 Curvature '28 Radial velocity. - 49 494 DEPARTMENT OF THE INTERIOR a. CORONA BOREALIS, 892 (b). 1907. June 27. G. M. T. 15 h 25" 9-10 EDWARD VII., A. 1910 Observed by W. E. HARPER. Measured by J. B. CANNON. Mean Corrected Displace- Mean Corrected Displace- Wt of Star ment in Velocity. Wt. of Star ment in Velocity. Settings. Settings. Revolutions. Settings. Settings. Revolutions. 2 73-0205 2 54-7740 * 72-8582 8479 0169 -24 52 1 54-0162 9814 0116 + [13-35] 2 72-4540 2 53-1495 2 57'8550 2 45-3208 i 57-8570 8288 0020 + ( 2-41)* 1 45-2668 2196 0191 -19-94 Weighted mean - 21 47 V a -16-98 Vd - '09 Curvature... - '28 *Not used. Radial velocity -38 8 1907. July 4. G. M. T. 15 h 38 a CORONA BOREALIS, 912 (a). Observed by \ Measured by/ Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 73 4621 3 54-0285 0243 0545 + [62 '731 1 73 0125 2 53'1130 72-8823 8823 0175 + 25-39 2 45'2818 I 72-4506 H 45-2930 '2848 '0461 + 48'13 if 54-7496 Weighted mean +43'58 V a -18-30 V d -14 Curvature ... - '28 Radial velocity + 24T> REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 495 a CORONA BOREALIS, 917 (a). 1907. July 5. G. M. T. 15 h 20 m Observed by J. S. PLASKETT. Measured by W. E. HARPER. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 72 "9847 2 53-1159 1 72 '8795 9040 0392 + 56'38 2 45-2826 i 72'4219 2 45-2955 2865 0478 + 49'90 54 7410 1 27'4935 4460 "0334 + 28-99 54-022- 0210 0512 + [58'93] 2 27-2942 Weighted mean +48'77 V a -18-45 Vd - -10 Curvature. , - "28 Radial velocity +29'9 1907. July 8. G. M. T. 15 h 36 m a CORONA BOREALIS, 919. Observed by J. S. PLASKETT. Measured by W. E. HARPER. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings, Settings. Revolutions. Settings. Settings. Revolutions. 2 72-9772 H 45-2712 '2697 '0210 + 21-98 1 72-8492 8372 0185 + 26-88 1 27-5298 5265 0300 +34-16 2 72 4058 l 30-9330 2 45 ' 2852 2 27'325 Weighted mean +26 86 V a -18-95 V- 72-4588 J 12-0294 9169 0655 + 49 06 O 45-3296 9- 11-6198 1 45 3064 2504 0117 + 12-21 _ Weighted Radial ve. *Check measurement. a CORON^E BOREALIS 1907. July 12. G. M. T. 16 h 25 m mean 4 25'76 V a -19-23 05 - -28 Curvature ocitv 4 62 iKTT. *PER. \, 939 (a). Observed by J. S. PLASI Measured by W. E. HAI Wt. Mean Of X Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 2 72 9412 72 7980 72-3774 45 2876 2 45-2344 27-4394 27-2776 2304 4837 0183 0035 -19-16 - 3-16 ,8200 0013 + 1-89 1 Weighted Radial ve mean 8-58 19-52 23 - -28 V a Curvature locitv . . . - 28-6 498 1907. July 13. G. M. T. 15 h 25" DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 a CORON^E BOREALIS, 941 (a). Observed by J. N. TRIBBLE. Measured by W. E. HARPER. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 72-9571 1 53-9164 9216 0350 -[36'57] 1 72'7891 7967 0220 -31'94 2 45-2737 2 72-3883 2 45-2395 2494 ooio + 1 05 1 54-0101 Weighted mean - 9 ' 95 V a '.. -19-64 Vd - -20 Curvature ... 28 Radial velocity . 30.1 1907. July 16. G. M. T. 14 h 37 m a CORONA BOREALIS, 944 (a). Observed by J. N. TRIBBLE. Measured by W. E. HARPER. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity Settings. Settings. Revolutions Settings. Settings. Revolutions. 2 72-9844 2 45-2506 2292 0095 - 9'94 1 72-8686 8938 0290 + 42-08 27-4712 4048 0078 - 6 57 li 72-4200 2 27-3130 2 45-2950 Weighted mean '20 V a -19-98 Vd - -11 Curvature . . " "2B Radial velocity -20"6 1907. July 16. G. M. T. 14 h 37 ra o CORONA BOREALIS, 944 (a)*. Observed by J. N. TRIBBLE. Measured by J. B. CANNON. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity 2 73 0086 2 53 1311 i 72-8748 8752 oioi + 15-09 2 45'3033 9? 72-4466 1 45 '2588 2290 '0097 -i'6'iij 2 54-7631 4 27 '5206 '4520 '0394 -r54 $ 54-0116 9915 0217 + [21 981 8 f 27'3153 Weighted mean + 7 ' 26 V d ........ Curvature. -19-98 - -11 - -28 "Check measurement. Radial velocity -13-1 499 SESSIONAL PAPER No. 25a 1907. July 18. G. M. T. 14 h 50" a CORONA BOREALIS, 951 (a). Observed by J. N. TRIBBLE. Measured by J. B. CANNON. Wt. 1 Mean Corrected of Star Settings. Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 73-0275 ' J 53 '9282 0274 '0576 + [6G ' SO 1 | 72-8907 '8738 0090 + 13-06 2 53 0075 2 72-4593 2 45-1272 2 54-6480 1 45-0922 '2386 '0001 18'0 Weighted mean. +2 53 -20-16 Vd - 14 Curva Radial velocity . ture ... - '28 - 18-n a CORONA BOREALIS, 951 (b). 1907 July 18. G. M. T. 15 h Observed by J. N. TKIBRTE. Measured by J. B. CANNON. Mean Corrected Displace- Wt. of Star ment in Settings. Settings. Revolutions. Mean Velocity. Wt. of Settings. Corrected Disp Star mei Settings. Revoli lace- it in Velocity, itions. 2 73-0220 1 53-8272 0264 0264 -[30 38] 72-8730 -8G16 '0032 2 724539 - 1 64 2 52-9927 i 2 45-1147 2 54'6277 45'0804 2395 0008 + 8-35 Weighted mean - 0'3l . .. -20-16 Vrf 14 Curva Radial velocity a CORON^E BOREALIS, 956 (a). 1!>U7. July 20. < G. M. T. 16 h 07 m ture . . . . - -"J8 -20 9 Observed by J. S. PLASKETT. Measured by W. E. HARPER. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity . Wt. Mean of Settings . Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 72-9731 2 45-3021 2932 0445 + 46 59 1 H 72 8743 72'412S 8653 0448 + 65-09 1 3 27-5473 27 3199 5493 0621 + 54-03 ? 45 '2925 Weighted mean +53'08 V a -20-37 V d -22 Curvature . . - "28 Radial velocity + 32'2 500 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 a CORONA BOREALIS, 963 (a). 1907. July 23. G. M. T. 14>>32" Observed by J. N. TKIBBLE. Measured by W. E. HARPER. Wt. lean Corrected Displace- Mean Corrected Displace- of Star ment in Velocity. Wt. of Star ment in Velocity. .tings. Settings. Revolutions. Settings. Settings. Revolutions. J 4670 i 54-0566 0256 0558 [ + 04-22] ! 8900 8860 0212 + 30-76 2* 50-0472 !'6944 V 8 ....' +30-76 V -2059" Vd '14 Curvature ... - '28 Radial velocity. + 9 -8 1907. Aug. 1. G. M. T. 14 h 06" o CORONA BOREALIS, 973 (). Observed by \ w E Measured by, I w< r " Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings. Lines. Revolutions. Settings. Lines. Revolutions. 2 72 '9868 2 45-2780 J 72-8440 8210 0023 + 3 34 1 45-2568 2624 0137 + 14 34 2 72-4220 Weighted mean + 10-67 Curvature Radial velocity -20-98 14 - -28 -10'7 1907. Aug. 1. G. M. T. 14 h 06 m a CORONA BOREALIS, 973 (a)*. Observed by W. E. HARPER. Measured by J. B. CANNON. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 73-0088 1 53 9750 9619 0079 - 9 09 1 72 "8800 8807 '0159 + 23 07 f 53-1240 2 * 72 '4485 2 45'2885 :::::: ivj 2 54 '7562 \ 45-2552 2402 0015 + 1 57 Weighted mean + 5'85 Curva'ure. Radi.vl velocity ...... -20-98 14 - '28 -15-5 * Check measuiement. REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 501 1907. Aug. 1. G. M. T. 14'' 20'" a CORONA BOREALIS, 973 (6). Observed by W. E. HARPER. Measured by J. B. CANNON. Mean Wt. of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings, Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 73 0342 i 45 '2752 2335 '0052 - 5'45 2 45-3153 Va - 543 V a -20-98 Vd -14 Curvature... - '28 Radial velocity - 26 8 a CORONA BOREALIS, 978. 1907. Aug. 3. G. M. T. 13" 02 Observed by J. S. PLASKETT. Measured by W. E. HARPER. Wt. Mean Corrected Displace- Mean of Star ment in Velocity. Wt. of Settings. Settings. Revolutions. Settings. 72-9938 2 45-2426 72-8526 8224 0037 + 5-37 1 27-4524 72-4294 2 27-2940 45-2828 Corrected Star Settings. 2434 4800 Displace- ment in Revolutions. 0054 0165 Velocity - 5'65 - 6-40 Weighted mean - 3'08 V a :. -20-98 Va - 08 Curvature ... - "28 Radial velocity - 24 ' 4 1907. Aug. G. G. M. T. 16 h 38" o CORONA BOREALIS, 986. Observed by \ w F HARPKR Measured by / W ' *" UARPBR - Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings. Settings. Revolutions. Settings. Settings. Revolutions. > 72 ' 9297 2 54-6972 I "2 '8025 "8363 0176 +25'57 14 53'0647 li 72 "3657 2 45-2377 53-9672 oooo 0434 +[50'08] 1 45-2437 2877 0390 + 34-00 Weighted mean +29'78 V a -20-96 Vtf - -27 Curvature ... - "28 Radial velocity. + 8-3 502 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 a CORONA BOREALIS, 986.* 1907. Aug. 6. G. M. T. 16 h 38" Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 72 '9624 1 54-0154 54-0019 0553 + [63-93] 1 72 8494 72-8504 0317 + 46'06 2 45-2934 2 72-3988 1 45-2948 45-2850 0363 + 38-00 1 54 '0288 Weighted mean + 41 " 22 V a -20-96 V d - "27 Curvature. . . - '28 *Check measurement. 1907. Aug. 12. G. M. T. 16 h 36" Radial velocity +19'7 a CORONA BOREALIS, 1006. Observed by ) w # HARP ., R Measured by / W> * WARPER - Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 72'8216 1 53-9092 53 9903 0205 + [23'66] l 72 '6801 72 "8664 ooie + 2 32 2 45-2372 2 72'2641 } 45-2140 45-2504 0117 + 12-25 2 53-9477 . Weighted mean + 7 28 V a -20 76 V d - '28 Curvature... - '28 Radial velocity. -14-0 1907. Aug. 15. G. M. T. 15 h 09" a CORONA BOREALIS, 1014. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 72'9915 2 53 9737 53-9813 0115 + [13-24] i 79 RSQfi 72 ' 8573 0075 <-10'88 2 53 ' 1065 f 72 ' 4290 2 45-2707 2 54 7321 \ 45-2197 45-2226 0101 + 1G-81 Weighted mean .. + i3'84 V a -20-58 Vd - -24 Curvature... - '28 Radial velocity. - 7-3 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 503 a CORONA BOREALIS, 1017. 1907. Autr. 22. G. M. T. lo Observed by"i, T7 Measured by } W - HAR R. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ! ment in Velocity. Settings Settings. Revolutions. Settings. Settings. Revolutions. H 45 - 7844 ' i 45-7576 45 2448 0061 + 6-37 V* + 6'37 V a -19-90 V Radif ited mean r 9-85 04 28 | + 5-85 'd urvature . il velocity -, REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a a CORONA BOREALIS, 1565. 09 1908. June 1. G. M. T. 18 h Observed by T. H. PARKER. Measured by W. E. HARPER. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 H 2" 2 1 2 2 72-9938 72-8490 72-4310 54-7550 54-0110 53 1370 45-2605 2 1 2 ,* 2 2 45-3014 27-4890. 27-3107 15-5442 15-4900 11 9275 11 6009 ,- 72-8648 oooo O'OO 27 4251 0125 + 10-85 15-4528 0105 - 8-13 53 9920 0222 + [25-56] 11-8338 0176 - 9-13 45-2355 0032 - 3-34 1908. June 1. G. M. T. 18 h 42'" Weigl V V c Radia a CORONA BOREAL ited mean 2-59 10-43 20 28 d - ur vature 1 velocity 13 5 \EK. IS, 1566. Observed by 1 T TT T>._ Measured by / 1< Wt. Mean Corrected of Star Settings. Settings. Displace- ment in Revolution?. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 2 2 45-2929 45-2461 43-5585 j 27*4641 27-3000 27-4107 0019 - 1-64 45 2267 0120 -12-52 1908. June 3. G. M. T. 16 h 32' Weigl V V C Radia a CORONA BOREAL ited mean 10-34 10-43 20 28 20-2 CETT. IPER. _ jj ur vature 1 velocity [S, 1571. Observed by J. S. PLASI Measured by W. E. HAI Mean Wt. of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. ' Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Weighted mean ............... + 2'40 V a ............................... -1102 Curvature . . Radial velocity - -07 '28 90 510 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 1908. June 3. G. M. T. 16 h 52 m a CORONA BORE ALTS, 1572. Observed by J. S. PLASKETT. Measured bj C. R. WEST-LAND. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 54'7690 2 27-3380 , 4 53-9965 53-1417 53-9706 0008 + [1-16] , 15-5674 15-5266 15-4394 0339 -26 24 2 45-3179 2 11-9767 ii'8434 ooso - 5'99 2 45-2866 45-2423 0036 + 3'76 2 11-6410 i 27-4982 27-4073 0053 - 4'60 Weighted mean - 3'98 V -1102 Vd 'OS Curvature... - '28 Radial velocity. - 15-4 a CORONA EOREALIS, 1572*. 1908. June 3. G. M. T. 16 h 52 m Observed by J. S. PLASKETT. Measured by T. H. PARKER . Wt. Mean of Settings . Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings . Corrected Star Settings. Displace- ment in Revolutions. Velocity. i 53 '9962 53-9677 0021 -f 2-411 2 27-3409 2 54-7700 1 15-5560 IS'4260 0473 -36 61 2 45 3195 2 IS'5286 1 2 45-2856 43 '5855 45 2396 0009 + 0-93 2 2 11-9830 11 '6401 11-8501 0013 - 9 74 2 27-5096 27-4153 0027 + 2 34 Weighted mean . Vd Curvature . * Check measurement. Radial velocity. - 8-41 -11 02 - '08 - '28 - 19 8 REPORT OF TEE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 511 a CORONA BOREALIS, 1581. 1908. June 5. G. M. T. 17 h 31* Observed by) w Measured by f W> HARPI , R HARPER. Wt. Mean of Settings . Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 72 9780 1 27 3975 27 4026 0100 - 8'68 1 72-8406 72-8688 0040 + 5'80 2 27 2433 2 72-4202 1 H'8584 11-8491 0023 - 1'72 2 45 '2545 2 11 5145 2 45-2387 45-2578 0191 + 19 94 Weighted mean ............... + 7'06 Vd Curvature Radial velocity. -11 62 - -14 - -28 - 50 1908. June 12. G. M. T. 16 h 56" a CORONA BOREALIS, 1601. Observed by \ w v WAMP _ R Measured by/ W - * HAKPKR - Wt. Mean of Settings. Corrected Star Settings. ' Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 72-9665 2 53-0720 1 1 72-8330 72'4060 72-8678 0030 + 4-35 2 2 45 2242 45'2410 45-2568 0181 + 28-18 2 54-7068 li 27-4228 27-4370 0244 + 21-27 i 53 9350 53 9725 '0027 + F3-111 I 27 2322 Weighted mean +2058 V a -13-59 Vi '. - -12 Curvature . . - " 28 Radial velocity + 6'6 25a 35 512 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 a CORONJE BOREALIS, 1G08. 1908. June 17. G M. T. 13" 53"' Observed by 1 u 7 u Measured by /W. E. HARPER. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings. - Settings. Revolutions. Settings. Settings. Revolutions. 2 72'9809 2 45-2620 1 72-8361 72-8662 0014 + 2-03 2 45-2390 45-2506 oiio + 12-42 2 72-4112 1 27-4892 27-4739 0613 + 53'21 2 54-7169 2 27-2621 1 53-9506 53-9716 0018 + [2-07] 1 11-9270 11-8964 0450 + 33-70 2 53-0941 2 11-5379 Weighted mean +23'76 V a .. -14-85 V d -07 Curvature... - '28 Radial velocity .. + 8'6 1908. June 22. G. M. T. 16" 27 m a CORONJE BOREALIS, 1623. Observed by J. S. PLASKETT. Measured by J. B. CANNON. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 54 '7556 1 27-4580 27 4130 0004 + 3 47 2 53-9719 53-9559 0139 -rie-ooi 3 27-2899 2 53-1320 1 11-9219 ii'8454 0060 - 4-49 2 45*2819 2 11-5853 1 45-2571 45 2511 0124 + 12 93 . Weighted mean + 3 97 V a -16-16 Vd -16 Curvature... - '28 Radial velocity . -12 ' REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a a CORONA BOREALIS, 1623. 513 1908. June 22. G. M. T. 16 h 27'" Observed by J. S. PLASKETT. Measured by J. B. CANNON. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 1 2 2 2 2 73-0044 72-8548 72 4483 54-7536 53-9681 53-1381 f 45-3000 45-2624 27-4675 27-2952 11 9274 11 5790 ~ 72-8598 0050 - 7-25 45-2364 27-4195 0023 0024 - 2-40 - 2'08 53-9531 0167 -[19-22] 11-8594 0080 + 5".9 *Check measurement. 1908. June 22. G. M. T. 16 h 40 m Weig \ C Radij a CORONA BOREAL ited mean 1-44 16-16 16 28 r d urvature - il velocity IS, 1624. 18 KETT. RPER. Observed by J. S. PLAS Measured by W. E. LD Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity 2 1 2 2 54-7898 54-0178 53-1597 45 3251 45-2880 H 27-4840 27-3131 11-9423 11-5883 27-4175 0049 + 4-34 53-9700 0002 [0-00] 11-8612 0098 + 7-34 45-2365 0023 - 2 40 1908. June 24. G. M. T. 15 h 26 Weigl V V C Radia a CORONyE BOREAL ited mean + 4-02 16-16 16 28 jj urvature ~ 1 velocity LS, 1628. Observed by J. S. PLASKETT. Measured by J. B. CANNON. Mean Wt. of Settings. Corrected Star Settings. Displace- ment in Revolutions, Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 54-7838 .', 53 9417 2" 53-1536 2 45-3060 1 45-2M r-l IN I-* i I ] 54 6727 53-9471 53-0497 45-2008 1 2 1 2 45-2097 44-1900 27-3961 27 1843 45-2817 0430 + 44-89 54-0011 0313 +36-03 27-4586 0460 + 39-93 Weighted V .. mean + 42 41 -18-18 14 - '28 Vrf Curva Radial ve a CORONA BOREAL 1908. July 6. G. M. T. 16'' 50 ture oclty + 23-8 .KK. TON. IS, 1665. Observed by T. H. PAR* Measured by J. B. CAN Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 1 72-9602 li 45 2173 45-2668 0281 + 29-34 1 72-8398 72 "8876 0228 +33 08 9 45-2240 72-3996 1 27-4083 27-4290 0164 + 14-24 2 54'6898 2 27-2265 4 2 53 9145 53'0501 53 9715 0017 + [1-96] 1 2 11-8914 11-4830 11,9154 0640 + 47-93 Weighted mean +31'18 V a -18-72 Vd '16 Curvature... - '28 Radial velocity + 12'0 518 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 a CORONA BOREALIS, 1673. 1908. JulyS. Observed by\ T R P . VKmi G. M. T. 14 h 59 m Measured by J ' Wt. Mean of Settings . Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings . Corrected ' Star Settings. Displace- ment in Revolutions. Velocity. 1 \ 2 \ 2 72-9993 72-8626 72-4371 54 7344 53-9855 53-1071 2 1 45-2746 45 2.S92 27-4564 27-2810 11-9283 11 5472 72-8721 0073 + 10-60 45-2382 27-4227 0005 0065 - 0-52 + 5-64 53-992C 0222 + [25-55] 11-8883 0369 + 27 -63 Weighted mean + 14 01 19-07 11 28 Vrf . . Cuiva Radial ve! a CORONA BOREAL 190S. July 8. G. M. T. 15 h 11 ;ure ocity . . . 5-4 'ON. IS, 1674. Observed by \ T -r> p. . XT Measured by j j - R CAM Wt. Mean of Settings . Corrected Star Settings. Displace- ment in Revohitions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 2 2 1 54 7242 53 9536 53-0947 45-2616 45-2583 1 2 2 27-4496 27 2631 11-8926 11-5351 27 4334 0208 + 18-05 53 9711 0013 + [ 1'50] 11-8651 0137 + 10-26 45-2703 0316 + 32 99 Weighted V,, .. mean + 18-98 19-07 11 28 V/7 Curva Radial ve a CORONA BOREAL 1908. July 10. G. M. T. 13 h 34 m ture ... locitv . . , 0'5 IS, 1683. Observed by W. E. HARPER. Measured by J. B. CANNON. Wt. Mean of Settings . Corrected Star Setting.". Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 1 2 73'0309 72-8884 72 4603 54-7682 54 0451 2 2 1 2 53-1334 45 3129 45-2667 27-4832 27-3188 72-8694 0046 + 6-67 45-2274 27 4112 0113 0014 -11 79 - 1-22 54 0211 0513 + [59-04] Weightec V- [ mean - 1 89 -19-38 oo 28 R v d . Curv adial v ature ^locitv . . . - 21-5 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 519 1908. July 10. G. M. T. 13 h 57 ra a CORON^E BOREALIS, 1684. Observed by W. E. HARPER. Measured by J. B. CANNON. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings. Settings. Revolutions. Settings. Settings. Revolutions. 1 73 0327 2 45-3009 i 72-8947 72-8737 0089 + 12-91 1 45-2694 45 2421 0034 + 3-54 1 72-4598 14 27-4744 27-4221 "0095 + 7'81 o 54-7653 ?- 27 '2995 i 53-9629 53-9399 6299 -[34-41] \ 11-9048 11-8363 oi5i -11-30 53-1347 11 5759 Weighted mean + 4'59 Va -19-38 Vd -04 Curvature... - '28 Radial velocity 15-1 a CORONA BOREALIS, 1697. 1908. July 13. G. M. T. 15 h 36 m Observed by J. S. PLASKETT. Measured by J. B. CANNON. Mean Corrected Displace- Mean Corrected Displace- .Wt. of Star ment in Velocity. Wt., of Star ment in Velocity. Settings. Settings. Revolutions. Settings. Settings. Revolutions. 1 72-9735 2 45-2596 i 72-8268 72 8608 0040 - 5-80 U 45-2284 45 2424 0037 + 3'86 72-4159 l| 27-4218 27-3975 0151 -13-11 2 51 7199 2 27-2712 1 53-9583 53-9828 oiso + [14-96] 1 11-8656 11 8236 0278 -20-82 2 53-0846 2 11-5495 Weighted mean ..................... - 8'35 -19-79 , ...................... - '19 Curvature ... .......... - '28 igh V a Radial velocity -28'6 520 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A: 1910 a CORONA BOREALIS, 1698. 1908. July 13. G. M. T. 15 h 42'" Observed by J. S. PLASKKTT. Measured by J. B. CANNON. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings. Settings. Revolutions. Settings. Settings. Revolutions. 1 73'OOGl 2 45-2766 1 72-8661 72-8691 0043 + 6-24 U 45-2388 45-2358 0029 - 3 03 1 72-4437 if 27-4391 27-4144 0018 + 1-56 2 54 '7384 2 27'2716 1 53-9504 53-9544 0154 -[17-72] 1 11-8994 11-8619 0105 + 7-86 2 53 1069 2 H'5450 Weighted mean + 1'84 V a -1979 v<* - '16 Curvature - -28 Radial velocity -18-4 a CORONA BOREALIS, 1711. 1908. July 15. Observed by G. M. T. 16 h 24 Measured by | J. B. CANNON. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings. Settings. Revolutions. Settings. Settings. Revolutions. 1 73-0341 U 45-2779 45-2420 0033 + 3 44 * 72-8891 72-8647 oooi 15 1 27-4705 27-4115 0011 - '95 2 54-7729 2 27'3061 H 54-0318 5.':! '9990 0292 +[33-61] 1 11-9256 11-8468 0046 34 2 53-1470 2 H'5865 2 45-3094 Weighted mean gt V a Vrf Curvature -{- 3 '71) -20-03 '22 '28 Radial velocity - 16'7 REPORT OF THE CHIEF ASTRONOMER [SSIONAL PAPER No. 25a 521 a. CORONA BOREALIS, 1721. 1908. July 24. G. M. T. 13 1 ' 0.3'" Observed by W. E. HARPER. Measured by J. B. CANNON. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. f Wt. of Star ment in Velocity. S.-ttings. Settings. Revolutions. Settings. Settings. Revolutions. 1 73 "0620 2 45-3273 I 72-9251 72 9711 0063 + 9-14 1 45-3040 45 2503 0116 + 12-10 1 72'5018 U 27-5037 27-4317 0191 + 15'57 2 54-7950 ?: 27-3187 .), 54-0282 53.9742 0044 + [5-06] i 11-9502 11-8812 0298 + 20-97 2 53-1587 2 11-5759 Weighted mean +15'25 V a -20-68 V<* '04 (Jurvature... - '28 Radial velocity. - 5-7 a CORON^E BOREALIS, 1722. 1908. July 24. Observed by W. E. HARPER. G. M. T. 13 h 21"' Measured by J. B. CANNON. Mean Wt. of : Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 1 I 73-0441 *i 72-9200 1 72 4735 2 ! 54-7704 i| 54-0159 2 53-1390 2 I 5 2 1 2 45 3021 45 3022 27-4681 27-2830 11-9141 11-5446 72-8872 0224 + 32-50 45-2738 27-4298 0172 + 36-64 + 14-93 53-9881 0183 + [21'06] 11-8766 0252 + 18-87 Weig \ \ C hted mean - 4 26 25 -20-68 04 - -28 r d urvature . . . Radial velocity + 5'25 522 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 a CORONA BOREALIS, 1739. 1908. July 29. Observed by J. S. PLASKETT. G. M. T. 15 h 34 m Measured by J. B. CANNON. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 2 2 1 2 73 0080 72 8406 72 4370 54-7106 53-9688 53-0733 2 2 ,' 45-2276 45-1618 27-3167 27-1926 11-7853 11-4290 72-8439 0209 -30-33 45-2078 27-3607 0309 0519 -32 26 -45 14 5i'0038 0340 -[39-13] 11-8623 0109 + 8-16 Wete \ \ C Radu a CORONA BOREAL 1908. July 29. G. M. T. 15 11 34 m ited mean. r a 29-78 20-68 24 28 r d - urvature il velocity .... 50 1KKTT. RKKR. [S, 1739.* Observed by J. S. PLAS Measured by T. H. PA Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 73-0854 2 45-3015 i 2 72 9133 72-5142 72-8398 0250 -36-27 1 J 45-2452 27-3747 45-2173 27'3581 0214 '0545 -22 34 -36'29 2 54-7789 2 27 2632 * 2 54-0256 53-1456 53-9903 0205 + [25-59] \ 11-8647 H'5022 11-8697 0183 +13-70 Weighted mean -18'01 Vo -20-91 Vd - 22 Curvature - '28 "Check measurement. Radial velocity. 39-4 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a a CORONA BOREALIS, 1748. 523 1908. July 81. G. M. T. 13 h 38 m Observed by T. H. PARKER. Measured by J. B. CANNON. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 1 73-0081 2 53 1007 i 72-8616 72-8641 0007 -10-15 2 45-2666 r 72-4501 1 45-1969 45-2039 0348 36-33 2 54-7326 U 27-3938 27-3994 0132 11 '45 1 53-9342 53 9445 0250 -[28-77] ?: 27-2521 Weighted mean - 19'53 V a -20-98 Va- - -14 Curvature - -28 Radial velocity . -40 9 a CORON^E BOREALIS, 1749. 1908. July 31. G. M. T. 13 h 38" Observed by T. H. PARKER. Measured bv J. B. CANNON. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings Settings . Revolutions. Settings . Settings. Revolutions. 1 73 0321 2 45 272* * 72-8767 72-8559 0089 -ii-9i U 45-2269 45-2281 0106 -11 07 72 4611 27-4144 27-4088 0038 - 3'30 2 54-7470 2 27-2523 1 53-9854 53-9816 0118 + [13-58] 1 11-8314 11-8384 0160 -11-98 2 53'1145 2 11 4999 Weighted mean - 9'46 V a -20-98 Va- - -14 Curvature - "28 Radial velocity. - 30-9 524 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 a CORONA BORKALLS, 170-1. 1908. Aug. 5. a. M. T. 15 h 15"' i )b>ri v<->d by J. S. PLASKKTT. Measured by -I. B. CANNON. Mean Wt. of Settings . 1 73-0055 i 72-9250 72-4451 2 54-7359 1 54-0637 2 53-1055 Corrected Star Settings . Displace- ment in Revolutions. Velocity. Wt. 2 72-9281 0633 + 91-85 11 2 54-0699 1002 + [115-33] 1 2 Mean of Settings. Corrected Star Settings . 1 >isplace- ment in Revolutions. Velocity* 45-2722 45-2899 27-4955 27 ' 2595 45-2913 27-4728 0526 0602 + 54-91 + 52-25 11-9402 11-5107 11-9365 0851 +63 74 , Weighted mean , -*- 58 ' 42 V a -20-96 V-i -23 Curvature . - '28 Rauia) velocity. i 37'0 a CORONA BOREALIS, 1773. 1908. Aug. 7. Observed by T. H. PARKER. G. M. T. 14 h 25 m Measured by J. B. CANNON. Wt. Mean of Settings . Corrected Star Settings . Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings . Displace- ment in Revolutions. Velocity, 2 1 2 2 n 54-7903 54-0770 53-1613 45-3261 45-3538 4 2" i 2 27-5854 27 3236 12-0157 115833 27-5087 0961 + 83 41" 54-0281 0583 + [67.10] 11-9397 0883 ; 6(> 14 45-3013 0626 + 65-35 Weighted V,, mean W12 -20-91 19 - -28 Ra v d . Curv;\ dial ve tivre . . . , locitv . . , + 47'7 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 525 a CORONA BOREALIS, 1775. 1908. Aug. 7. G. M. T. li>> 40" Observed by T. H. PARKER. Measured by J. B. CANNON. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings . Settings. Revolutions. Settings . Settings . Revolutions. 1 73 0279 2 45-3045 * 72-9227 72-9056 0408 f 58-20 H 45 3313 45 3004 0617 + 64-41 1 72-4568 1 27-5296 27-4692 0566 + 49-13 9 54 '7633 2 27 ' 3107 1 54-0103 53-9888 0190 + [21 -87] 1 12-0051 ii-9305 0791 + 59-25 2 53-1363 2 11 5821 Weighted mean .... + 58 ' 54 V -20-91 V d 19 Curvature ... - ' 28 Radial velocity +37'5 a CORONA BOREALIS, 1798. 1908. Aug. 20. G. M. T. 13 h 05 Observed by T. H. PARKER. Measured by J. B. CANNON. Wt. Mean of Settings . Corrected Star Settings . Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings . Displace- ment in Revolutions. Velocity. 73 0365 2 53-1332 72 8789 72 "8528 0120 -17'41 2 45-2876 72 '4693 1 45 2516 45-2376 0011 - 1-16 54 '7634 | 27-4337 27 4011 0115 - 9-98 54 -0034 53-9821 0123 + [14'16J 2 27-2794 Weighted mean - 7'42 V ffl -20-11 V d -16 Curvature... '2i{ Radial velocity - 28 526 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 a CORONA BOREALIS, 1798* 1908. Aug. 20. G. M. T. 13" 05" Observed b\ T. H. PARKER. Measured by .T. B. CANNON. Mean Corrected Displace- Mean Corrected ' Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings . Settings . Revolutions. Settings . Settings. Revolutions. 2 73-0592 2 45 3184 i 72 9039 72-8549 0099 -14-36 1 45-2919 45-2471 0084 + 8-76 2 72 "4926 1 27 ' 4682 27-4132 0006 + 0'52 2 54 7899 2 27-3016 * 54-0289 53-9824 0126 + [14-50] 1 11-9196 11-8679 oies + 12 36 2 53-1569 2 11-5585 + 4' 13 Radial vel * Check measurement. a CORONA BOREAL 1908. Ang. 21. G. M. T. 15 h 01 ra V a 20-11 16 28 Curvature ocity _ 16 4 1 IS, 1809. Observed by ) T T> n. wv Measured by/ J ' K OANN Wt. Mean of Settings . Corrected Star Settings . Displace- ment in Revolutions. Velocity. Wt. Mean of Settings . Corrected Star Settings . Displace- ment in Revolutions Velocity. \: 1 2 73-0208 72-8951 72-4582 54-7565 54-0087 53 1219 2 1 1 2 45-2855 45-2607 27-4744 27-2787 11-9107 11 5418 72-8835 0187 + 27 13 15-2488 27 4424 0101 0298 4 10-54 i| + 25-87 I 53-9964 0266 + [30'62J 11-8762 0248 + 18'58 jl i Weighted mean ... -I 18-54 20 00 25 28 V d Curvature Radial velocity .. - 2'00 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 527 a CORONA BORE ALTS, 1816. IMS. Augr. 24. G. M. T. 13 h 12 m Observed by W. E. HARPER. Measured by J. B. CANNON. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity Settings . Settings . Revolutions. Settings . Settings . Revolutions. _ 54-7407 1 45-3087 45-2922 0535 + 55'85 i 5 \ 0267 54-0182 0484 + [55-71] * 27-5152 27-4672 0546 +47-38 2 53-1212 2 27'295C 2 45'2902 ' Weighted mean +53'03 V a -19-63 Va - -20 Curvature... - '28 Radial velocity + 32'9 a CORONA BOREALIS, 1817. 1908. Aug. 24. G. M. T. 13 h 27" Observed by W. E. HARPER. Measured by J. B. CANNON. Mean Corrected Displace- Mean Corrected Displace- \Vt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings . Settings . Revolutions. Settings . Settings . Revolutions. 1 73-0283 2 45-2794 4 72-9461 72-9283 0635 + 92-13 1 45-2977 45-2920 0533 +55-64 1 72-4579 i 27-5221 27'5085 0959 + 83'24 2 54 ' 7488 2* 27'2603 1 54 0279 54 -0227 0529 + [62 -66] i 11-9477 11-9257 0743 + 55-65 2 53 1145 2 H'5295 Weighted mean +68'45 V a -19-63 Vd - -20 Curvature ... - ' 28 1908. Aug. 25. G. M. T. 13 h Radial velocity + 483 a CORONA BOREALIS, 1827. Observed by\ j r> Measured byj ' Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings . Settings . Revolutions. Settings . Settings . Revolutions. 2 54-6765 1 45 2167 45-2857 0470 + 49-06 1 53-9543 54-0213 0515 + [59'28] i 27-4307 27-4547 )121 + 36-54 2 53-0434 2 27 2226 2 45-2046 Weighted mean ........................ +46'56 V a ............... -19 51 Vd ................ - -17 Curvature ........... - '28 Radial velocity + 26 - 25036 528 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 a COROX/E BO RE ALLS, 1836. 1908. Aug. 27. Observed by \ T R n. vvnv G. M. T. 14" 34"' Measured by i J B CANNON. Wt. Mean of Settings . Corrected Star Settings . Displace- ment in Revolutions. Velocity. Wt. Mean of Settings . Corrected Star Settings . Displace- ment in Revolutions. Velocity. 1 2 1 2 73 0226 72-8899 72-4579 54-7549 53-9889 53 1241 2 1 2 2 2 45-2911 45-2916 27-4900 27-2740 11-9036 11 5409 72-8770 0122 + 17-70 45-2741 27-4623 0354 0497 + 36-95 + 13-13 53-9763 C065 + [ 7-48] 11-8701 0187 + 14 00 Weighted Radial vel< a CORONA BOREAL 1908. Aug. 28. G. M. T. 13" nean + 29-74 10-0 NON . -19-21 28 - '28 4- Vd Ourvature xiitv [S, 1841. Observed by\ T r> r. v Measured by/ J - B CAN Wt. Mean of Settings . Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings . Corrected Star Settings . Displace- raent in Revolutions. Velocity. 1 1 2 1 73 0259 72-8870 72-4641 45-2921 45-2848 2 1 2 27-5064 27-2849 11-9382 11-5626 27-4684 0553 + 48-43 72-8701 0053 + 7-69 11-8832 0318 + 23.82 45-2663 0276 + 28-81 Weighted i ( Radial vel nean + 24 94 5-4 V a -19-03 19 - -28 + Curvature ocitv . . , ur.roRT OF THE CHIEF ASTRONOMER 529 SESSIONAL PAPER No. 25a 1908. AUK- - s - G. M. T. 13 h 14" a COROX^E BOREALIS, 1S42. Observed by I T r> Measured by } J - B Wt. Mean of Settings . Corrected Star Settings . Displace- ment in Revolutions. Velocity. Wt. Mean of Settings . Corrected Star Settings . Displace- ment in Revolutions. Velocity. 1 73 0092 2 45-2878 -f 72-8733 72-4448 72-8738 0090 + 13-06 1 i 45-2838 27-4705 45-2696 27 4412 0309 0286 + 3*2 26 + 24'82 o 54-7462 2 27 '2762 a 54-0117 53-1214 54-0051 0353 + [39-63] 2 11-9601 11 5452 11-9223 -.0709 + 53-10 Weighted mean +30'60 V a -19-03 Vd - 20 Curvature ... - ' 28 Radial velocity. 11-1 a CORONA BOREALIS, 1852. 1908. Aug. 31. Observed by W. K. HARPFR. G. M. T. 13 h 17 m Measured by J. B. CANNON. | Mean Wt. of Settings . Corrected Star Settings . Displace- ment in Revolutions. Velocity. Wt. Mean of Settings . Corrected Star Settings . Displace- ment in Revolutions. Velocity. 1 73-0311 \ 72-8743 1 72 4637 2 45-2785 1 45-2366 1 1 2 ,* 27 4462 27-2515 11-8686 11-5056 27 4423 0297 + 25-78 72-8536 0112 -12-89 11-8702 0188 + 14-08 45-2317 0070 - 7-31 m Weighted mean. . . V,. + 3-66 18 53 22 28 15'4 Radial vel Vd Curvature ocitv. . . - 530 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 a CORONA BOREALIS, 1852*. 1908. Aug. 31. G. M. T. 13 h 17" Observed by \V. E. HAKPER. Measured by J. B. CANNON. Wt. Mean of Settings . Corrected Star Settings . Displace- ment in Revolutions. Velocity. Wt. Mean of Settings . Corrected Star Settings . Displace- ment in Revolutions. Velocity. 1 73-0047 | 27-4278 27 ' 4397 0271 + 23'52 i 72-8550 72-8598 0050 - 7'25 2* 27 2347 72-4409 H'8520 11-8750 0236 + 17 68 2 45-2570 2 11-4840 1 45-2188 45-2354 0033 - 3 45 Weighted mean + 4 05 V a -18-53 V/-;/M,Y7.i//-;\y OF THE INTERIOR a CORONA BOREAL IS, 1883. 1908. Sept. 14. G. M. T. 13 h 07' 9-10 EDWARD VII., A. 1910 Observed by J. S. PLASKETT. Measured by J. B. CANNON. Wt, Mean Corrected Displace- Mean Corrected Displace- of Star ment in Velocity. Wt, of Star ment in Velocity. Settings. Settings. Revolutions. Settings . Settings . Revolutions. 54 7551 2 27-2799 54-0166 54 0060 0362 + [40-57] * 15-5465 15-4985 0252 + 19-50 53-1201 2 15-4467 45-2864 1 H'9188 11 ' 8737 "0223 -^16-70 45-2824 45-2696 0309 + 32-26 2 11-5523 27-4653 27 4323 0197 + 17-10 Weighted mean +22'85 V a -15-95 Vrf - -23 Curvature - '28 Radial velocity. + 6-4 1908. Sept. 19. G. M. T. 12 h 02 m a CORONA BOREALIS, 1894. Observed by J. S. PLASKETT. Measured by J. B. CANNON. Wt. Mean of Settings . Corrected Star Settings . Displace- ment in Revolutions. Velocity. Wt. Mean of Settings . Corrected Star Settings . Displace- ment in Revolutions. Velocity. 2 73-0180 2 45 3163 , 72-8619 72'4620 72-8515 0133 -19-30 i 45-2773 27-4673 45.2346 27-4000 0041 '0126 - 4-28 -10 94 2 54-7725 a* 27 3142 o 1 53-9865 53-1454 53 9545 0153 -[17-51] 2 2 11-9190 11-5926 11-8336 0178 -13-33 Weighted mean -11'96 V a -14-58 V d - -22 Curvature '28 Radial velocity . - 27 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a a CORONA BORKALIS. 1895. 533 1908. Sept. 19. Observed by J. S. PLASKETT. G. M. T. 12" 17 m Measured by J. B. CANNON. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 2 1 2 2* 73-0038 72-8573 72-4388 54-7388 53-9565 53 1120 2 1 i 45-2814 45-2429 27 4293 27 2643 11-8895 11 5373 72-8633 0015 -2-18 45-2351 27-4118 0036 0008 - 3'76 - 0-69 54-9580 -0118 -[13-58] 11 8595 0081 + 6-07 Weighted Radial ve a CORONA BOREAI 1908. Sept. 19. G. M. T. 12 h SO*" mean + 1-26 14-58 22 28 V a . . . . V p. ..., Measured by J J - RCAJsNON - Wt. Mean of Settings. 72-9672 72-8800 54-7508 Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 1 45-3092 72-9220 0572 + 82-99 1 45-2928 45-2928 6i85 + 19-31 Weighted mean +39'88 V a - -38 V * TEMPERATURE. d r*^~* STAK. ft D Plate. Date. "o . d Angle at end. Room. Prism Box. A Seeing. ,: u- E ^w 43 b > o 55 O 1 a 3 P Beg. End. Beg. End. ?* 02 i o 1906. h. in. in. h. m. Fahrenheit. Centigrade. 5 Aquilae . 368 Seed 27. Aug. 6 17 35 85 2 55W. 71-0 69 4 27-7 28-0 001 Good... H n 377 .. R. n 1515 40 70 1 07W. 68-2 66-0; 25'6 25-6 001 ii H ii 382 , . n 2415 45 90 2 15W. 64-0 62-1 22-8 22-9 001 Fair H 390 n Sept. 10;i5 30 60 2 50W. 69-0 67'0 26'7 26-7 -001 Good... H ; ; 399 i 27- 14 45 60 3 15W. 60 59'6 ! 21-8 21-8 -001 M H ,- . . 413 27 Oct. 23 13 45 90 4 10W. 50-3 46'2 15'1 15 3 001 Dancing H 1907. Centi Bfrade II 803 IL n May 31 19 04 25 35E. 12-6 12 6 18 7 18 7 -001 Good... P ,, 818 n June 10 19 13 20 15W. 12-4 12'1 17'8 17'8 -0012 ii P 11 904 M July 2 18 12 24 40W. 13-5 14'0 17-0 17'0 0014 n H , 923 n ,,' 8 18 02 25 55W. 20 2 20 1 22-3 22-2 0012 Poor to . fair. . . T> II 930 n 9 16 33 30 30E. 21 5 20 9 25-0 25-0 0012 Good . . . H II 938 ii 10 16 30 30 28E. 22 6 22 4 24-5 24-5 0012 Fair to poor. . P II 966 n 25 16 30 60 48W. 21 5 21 5 28-0 27'8 0014 Poor.... H 980 M Auar. 3 14 40 30 45E. 19-5 19'5 24 24-1 0012 P 1 982 ,i !! ,r 5 16 36 28 1 10W. 17-6 17 6 21 21 0012 Fair to poor. . P II 1034 n Sept. 6 15 44 41 2 35W. 18-3 18'0 21'0 20-5 0012 Fair .. . . T II 1049 10496 " " } 18 13 56 47 1 42W. 14-0 12'5 17 1 17-1 0014 T 1908. II 1543 ,, n May 18 20 06 30 00 15 5 15-0 23-423 4 0016 Hazy... H II 1550 n 22 20 34 42 39W. 19-0 19'0 25-025-0 0017 Fair.... H II 1575 ' I June 3 20 01| 40 45W. 13 12'5 18-318-3 0015 ,, H II 1584 n 5 20 35; 40 1 30W. 14-0 14 3 24-424 4 0016 Notgood PI II 1633 .1 24 18 31 37 40W. 19'0 19'0 27-527-5 0015 Good... H 1642 n 26 18 52 55 1 20W. 17'6 17 5 30-230-0 0016 n PI II 1650 n 27 18 09 35 30W. 19-5 19-1 23-623-4 0014 p ,, 1660 July 3 18 35 50 25W. 20-5 20-1 25 125 1 0016 Fair.... HP 1 ., '.'.\ 1678 ,, 8 18 10 40 1 15W. 17-0 17-5 21 6,21-6 0015 Good... C-H ii 1690 , 10 18 35 45 1 55W. 21-1 20-5 27-528-0 0016 ii PI n 1695 11 18 27 35 1 45W. 26-0 25 4 29 829-7 0015:Fair.... P ii 1703 ,. 13 18 52 45 2 25W. 18'2 18 23 023-0 0015 Good... PI n 1753 31 16 41 32 1 10W. 19'5 19 5 26-025-9 0015 n P 1 n 1754 , 31 17 17 34 1 48W. 19-5 19 25-9 25-6 0015 ii ... H 1768 Aii&r. 5 18 05 40 2 55W. 20'8 20'5 26 7 26'5 0015 P-C H 1783 , ii - w r>' * .. 15 17 38 30 3 05W. 18-0 17 6 22-5 22-4 0015 Fair.... P 1837 " , 27 15 03 35 1 20W. 18'0 17 23 223-0 0015 Good... C 536 DEPARTMENT OF THE INTERIOR 1906. Aug. (i. G. M. T. 17" 35' 5 AQUIL/tt oiis. 9-10 EDWARD VII., A. 1910 M^bj} W ' **- Wt. Mean of Settings. Computed Wave Lengths. Corrected Wave Lengths. Normal Wave Lengths. Displace- ment. Velocity. 3 S 68 '3790 4528-798 3 65-3512 4494-626 .738 1 64-1176 4480 '972 ooo 400 466 -26 '76 2 63-6677 4476-194 185 2 . . 62-7948 4466'79l '727 61-5939 4454-023 973 552 579 39'63 3 . .... S 56-8011 4404-927 2 . 54-6445 4383-756 "720 3 . 50-0285 4340 237 184 634 450 31'05 3 . 48-4614 4325-992 939 3 S 46-4500 4308-081 1 45-4172 4299-044 074 3 44-8605 4294-217 301 2 44-3248 4289-601 642 032 390 -27 '22 Weighted mean - 31 16 V a -10-00 Vd - '16 Curvature 50 Radial velocity -41 '8 1906. Aug. 15. G. M. T. 15 h 40" 5 AQUIL^E 377. Observed byK v Measured byj W ' HARPFR UARPER - Wt. Mean of Settings. Computed Wave Lengths. Corrected Wave Lengths. Normal Wave Lengths. Displace- ment. Velocity. 2 S 70 '1969 4549-642 2 70-1460 4549-039 039 642 603 -39'73 i... ..' '.... 68-8403 4533 723 '753 168 415 27-43 3* 68-4118 4528'757 '798 2 .... 65-4082 4494-722 '738 2 64-1638 4481-013 953 400 447 29'90 2 63'7291 4476-277 185 A... 63-0706 4469-152 062 545 485 32-36 2 62 8551 4466-835 '727 A 58 1412 4417-700 670 '038 368 24-95 3 S 56 '8682 4404-927 2 54 '6973 4383 ' 606 '720 3 50-0813 4340 115 184 634 450 31-05 3 48 '5181 4325-926 939 3 S 46 '5100 4308-081 2 44-9317 4294 '348 301 1 44-9073 4294-138 301 1 . . ... 44'3830 4289-632 590 032 442 -30-85 Weighted mean ................... -30'89 V a ...... ....... .. . . ......... -13-62 Va ........................... - "19 Curvature .................... - "50 Radial velocity .................... -45 '2 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 537 1900. Aug. 24. G. M. T. 15 1 ' 45" 5 AQUILjE 382. Observed by } Measured by } HARPER. Wt. * Mean of Settings. Computed Wave Lengths. Corrected Wave Lengths. Normal Wave Lengths. Displace- ment. Velocity. 9 70 1122 4549-520 642 ] .. .... 70-1029 4549-410 530 yos '375 -24 '71 3 .. 868 3400 4528-798 1 .. 67 "7987 4522-566 558 '855 297 19'69 1 65-9371 4501-472 505 2 66-3329 4494 735 "738 1 .. 64-0791 4480-926 930 400 470 31'44 a 63-6431 4476 176 185 9 62-7647 4466-688 727 1 59-7630 4435 058 078 450 372 25'14 2 S 56 '7937 4404-927 1 56 3165 4400-188 188 '738 5M) 37-45 i .. 55-7715 4394-808 804 286 482 SS'W 2" 54-6357 4383-715 720 A 53-7124 4374-809 821 103 282 19-31 2 ... 50-0145 4340-120 134 634 500 34-50 2 48-4534 4325-930 939 1 . .. 47-9225 4321 164 9 S 46 -4482 4308 081 164 r> 44-8650 4294'280 soi 1 44 '8327 4294-002 '018 '301 283 19 '78 r 44-3189 4289-578 '596 032 .436 -30'52 Weighted mean -27'54 v a -16'98 Vt - .12 Curvature - -50 Radial velocity . . . - 45-1 1906. Sept. 10. G. M. T. 15 h 30" 1 5 AQUIL.E 390. Wt. Mean of Settings. Computed Wave Lengths. Corrected Wave Lengths. Normal Wave Lengths. Displace- ment. Velocity. 1 65-2901 4494-811 '738 1 64-0719 4481 396 360 400 040 - 2'67 1 63 '6037 4476'2% 185 2 54 "5817 4383'730 720 ^ 49'9026 4339 632 620 640 020 - 1/38 3 48 '3953 4325 ' 945 939 Weighted mean - 2'00 V a -22-26 Vd - -19 Curvature - '28 Radial velocity -25'0 538 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 1900. Sept. 27. G. M. T. 14M5 m 5 AQUIL/E 399. Observed by "I 7 i? TT Measured by ) W - *~ HARPER. Wt. Mean of Settings . Computed Wave Lengths. Corrected Wave Lengths. Normal Wave Lengths . Displace- ment. Velocity. 3 70-1090 4549'618 642 1 68 7305 4533'425 '432 '419 013 + 0'85 S 68 '3316 4528 '798 3 .. 65'3312 4494-755 738 2 . . 64 '7742 44S8-581 '573 495 078 + 5'21 1 64-1215 4481-405 "405 '400 005 + 0'33 3 . ... 63-6427 4476'178 185 3 62 '7675 4466'710 '727 1 ..... ... 62 '3372 4462-093 109 165 '056 - 3'75 2 .... 62-0765 4459-309 301 1 61-1665 4449'662 676 785 109 - 7-33 1 58 0743 4417-705 695 884 189 -12-81 S 56 '8037 4404-927 1 55 '8229 4395-202 210 201 009 + 0'61 1 54'6149 4383'677 '720 1 53 "6987 4370'905 '144 2 50'0504 4340'559 564 "634 070 - 4-83 2 48 "4750 4325 ' 930 '939 S 46 ' 4725 4308 ' 081 - 2 44'89.">7 4294'319 '301 2 44-3930 4289-984 964 032 068 - 4-75 A. . 42-1961 4271-329 '305 325 020 - 1-40 Weighted mean . - 2'68 V a -25'74 V 35"' Measured by / T - H ' PARKER - Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 1 1 1 2 1 2 1 1" 1 2 59-8185 59 6231 57 7645 56-6595 53-9346 53-1106 52-3912 51-7052 50-9223 50-0435 48-7062 45 2770 1 2 2 1 2 1* 1 1 45-1990 37-9604 37-2349 36-1205 35-1146 35-4265 30 8236 27-3774 27-2576 18-8335 18.8776 1958 0429 44-78 6140 7645 0605 0623 -74-41 75-00 2404 4255 1186 0484 0707 0304 46 41 67 23 28-51 9376 0322 37-06 3908 7022 9183 0240 0553 0348 27-14 62-04 38-69 8176 3664 0580 0462 52-08 40-10 0441 -35-23 7012 0618 67-10 Weighted mean 51-40 09 28 V a + 16-22 Curvature Radial velocity -35' 5 1908. June 24. G. M. T. 18 h 31 m 5 AQUIL.E 1633. Observed by W. E. HARPER. Measured by T. H. PARKER. Mean Corrected Displace- Mean Corrected Displace- Wt. Star ment in Velocity. Wt. of Star ment in Velocity. Settings. Settings. Revolutions. Settings. Settings. Revolutions. 2 59 8112 1 45.2090 2005 0382 39-88 1 57 '7871 "7941 0327 -39'37 2 44 '2642 2 57 8218 2 41'2960 i 55-4842 4887 0353 41-33 1 40-4965 4875 0385 38-09 2 54 7384 2 35-4349 1 53 9350 9365 0333 38 32 1 35-3907 3857 0419 39-42 2 53 1133 | 27-3962 3792 0334 -28-99 2 45-2822 2 27'2636 Weighted mean -3791 V + 8-74 V d -00 Curvature "28 Radial velocity. -29 5 548 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 5 AQUIL^E 1642. 1908. June 26. Observed by \ rr. T> . G. M. T. 18 h 52 m Measured by J 1- W ' rARKER - \Vt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 1 ! 2 1 3 1 3 1 2 1 3 1 1 59-8137 59-4942 58-9788 58-5962 57-8290 57-7667 56-6748 53-9205 53-1059 51-6633 48 7623 48-7182 45-2623 45-1842 44-1888 2 2 J i j 2 2 1 2 2 1 1 2 43 5225 42-6036 42-1050 41-7834 40-4726 39-7305 37 9465 37-6986 37-2113 35-4224 30-8643 30-7867 27 3707 27-2482 6166 0230 23-34 9748 5922 0659 0057 - 80-46 6 93 7807 4755 0352 0413 35-41 40-96 7637 0631 75-97 9215 0483 55-59 7096 2218 0451 0670 43 47 64-25 6683 0892 100-08 7272 0368 39 94 7907 3691 0849 0434 80 64 -37'67 1967 2018 0420 0574 43-84 59-29 Weighted mean 47 " BO V a + 7'87 Vd - y 28 Curvature Radial velocity - 39'8 1908. June 27. G. M. T. 18 h 09" 5 AQUIL^E 1650. Observed by J. S. PLASKKTT. Measured by T. H. PARKER. Wt. Mean of Settings. Corrected - Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 59-8350 1 40-507C 4860 0400 39-68 2 57'8130 '7880 0388 -46'71 2 39 '7571 2 57 '8512 U 39-6936 6736 0532 52 34 1 2 56-9804 56-6977 9559 0096 11-40 l' 3 38-7283 37-9723 7123 0400 48-70 1 2 55-1051 54-7645 0841 0411 47-92 1 1 37-2502 36 4397 2362 4257 0526 0715 50-44 67 '28 li 53 9517 9337 Qsei 41 55 2 35 '4463 ? 53-1253 2 30-9004 1 , 4 51-6990 49 3733 48 '7901 6860 3583 0715 0091 80-22 10-21 H 2 30-8548 27-3920 27 "2785 8248 3600 0508 0526 45-70 45-65 1 2 48-7440 45-2955 7270 0370 40 14 i 24-8214 24-1079 7912 0789 0554 0543 46-86 45-12 2 45-2045 1835 0552 57 62 2 24 '8754 1 44'2292 2077 0515 53' 19 2 22 '5904 2 43-5514 1 22 5118 4782 0786 65-08 2 42-1240 1 18'8332 7323 0609 -48-65 1 41 2768 2558 '0414 41 '40 2 18'8943 i 40-7092 6882 0610 60-79 Weighted mean - 48'20 V a + 7-54 V d - 04 Curvature . . '28 Radial velocity - 41-0 REPORT OF TEE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 549 1908. June 27. G. M. T. 18 h 09 S AQUIL.-E 1660. Observed by J. S. PLASKETT. Measured by T. H. PARKER Wt. Mean of Settings . Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings . Corrected Star Settings . Displace- ment in Revolutions. Velocity. 2 o9'8256 2 45 2745 1 2 57-7919 57 '8327 7829 0070 - 8.42 ! 4 45 2107 44-2220 2097 2215 0290 0377 30 27 38'94 , 56 9519 56-6750 9499 0206 24.55 1 2 41-7726 41-2848 7741 0575 57-84 2 54-7459 2 41-2964 1 1 53-9418 53-7200 9398 7215 0300 0360 34 53 40-39 1 2 39-0028 37-9669 9838 0325 31-75 1 2 48-7544 48 ' 7063 7579 0079 8-57 1 2 37-2796 35-4331 2726 0162 -15-53 Weighted mean -29'35 V a + 7-66 Vd -00 Curvature ... ' 28 Radial velocity. - 21-9 5 AQUIL^E 1678. 1908. July 8. Observed by J. S. PLASKETT. G. M. T. 18 h 10 m Measured by T. H. PARKER. Wt. Mean of Settings . Corrected Star Settings . Displace- ment in Revolutions. Velocity. Wt. Mean of Settings . Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 a J i" 2 1 2 1 2 2 1 1 2 1 2 q 59-8005 58-9967 58 5482 57 '7767 57-8125 56 9345 56-6620 53 9232 53 1017 53-1317 Sl'7239 48-7590 48 7919 47-4680 45-3027 45-2398 44-2427 2 2 2 2 14 l| 2 2 1 1 2 2 J* 14 2 \ 43-5657 41-8142 41 3185 37 9962 37-7667 37 2799 35-4685 30-9250 30-8610 27-4311 27-31f',6 24 9101 24-8730 22-6292 22-5788 18-9394 18-9059 0037 5552 7837 0370 0427 0431 -45-21 51-88 51-89 7845 0471 47-38 7297 2429 0250 0459 24-10 44-01 .9415 0240 28-60 9322 0376 43 27 8064 3611 0692 0515 62-14 44 70 7039 7370 0536 0270 60-13 29-29 8080 0372 31-50 4434 0270 28-89 5063 0505 41-81 2138 2157 0249 0435 25-99 44 93 8099 0335 -26-76 Weighted Radial vel 38-83 09 28 v fl + 2'80 V G. M. T. lS h 37"' Measured by / T " H " FARKt - R - Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 1 2 2 2 1 2 1 2 59-8492 57-823* 57-8053 55-1478 53 9789 54-7702 53 6528 53 1388 47-4598 45-2945 2 4 ,* 1 2 1 1 2 45-2276 44-2779 44-2522 43-5578 43-5248 39-7623 38-7677 37-7768 37 9904 2066 0321 33-51 7873 0395 -47-55 2336 0256 26-44 1183 9519 0069 0179 8-04 20-60 5053 '0279 28-59 6260 0415 47 '6u 7407 '0116 "7483 -0161 11-29 -15-52 4377 0327 34-98 Weight ed mean 27 11 12 28 V a .. + 1-71 Vrf... Curvature Radial i velocity . . . - 26-1 1908. July 11. G. M. T. W h 27'" 5 AQUIL.-E 1695. Observed by J. S. FLASKET']'. Measured by T. H. PARKER. Mean Corrected Displace- Mean Corrected Displace- Wt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings. Settings. Revolutions. Settings. Settings. Revolutions. 2 59 '8527 f 2 45-3050 1 59-6739 6354 0391 -48 'is * 45 2435 2215 0172 17-95 A 59-0715 '0335 0396 48-39 2 44-2905 57-8545 8185 0083 11-19 * 44-2539 2224 0368 37-97 2 57 '8587 2 42-1319 A 56-9778 9428 0233 2f 77 H 41-8032 7749 0567 57-04 2 56 ' 7102 2 39 '7632 1 55-1281 0941 0311 36-26 1 38-7665 7405 0118 11-49 2 54-7768 2 30-9112 1 53 9813 9473 0225 25 89 * 30 8476 8146 0610 54-74 2 53 1442 1 27-4370 3990 '0136 11 '80 1 52'4120 3790 '0358 40 48 2 27 '2825 1 51'7425 '7085 0490 54-97 2 18-8835 2 48'8042 1 18-8525 8i24 '0310 -24'8 H 47-4810 4485 0219 23 43 Weighted mean -35'50 V a +1-20 V d -12 Curvature - '28 Radial velocity - 34 6 REPORT OF THE CHIEF ASTRONOMER SESSIONAL PAPER No. 25a 3 AQUIL.E 1703. 551 1908. July 13. Observed by \ T P . B1 G. M. T. lS h 52 Measured by / *" Mean Wt. of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 59-8090 57-7842 56 9494 54 7423 2 45 2766 45 1916 2" 43 5362 1 43 4567 2 1 2 1 1 2 2 1 37-9609 37 2499 30-8904 30-8531 27-4061 27-2758 22-5816 22 5331 7832 9484 0436 0171 - 52 49 20 38 2469 0419 40-18 833i -0425 3769 -0357 38 15 30-98 1896 0491 51 26 4587 0745 76-36 5083 0485 -39 77 Weight* Radjal i 5 AQUIL^E 17 1908. July 31. G. M. T. 16" 41 d mean 43 " ' 16 >8 V a + 36 - : Curvatu 7 elocitv re -43'- i 53. Observed by\ T H P AKKWR -1 ji_ t 1 . 11. -I AKKKK. Measured by ) Mean Wt. of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment .in Revolutions. Velocity. \ 2 30-8945 1 30-8828 L>7-4102 2" 27-2757 2 1 2 1 22 5725 22-5388 18-8774 18-8637 8588 -oies 3822 '0304 -15-08 26 38 5231 0387 32 04 0137 -10-94 i i Weighted mean 22-81 7 60 09 28 V Curvature . dial velocity -30'7 250 3S DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 5 AQUILJE 1754. 1908. July 31. Observed by W. E. HARPER. G. M. T. 17 h 17 m Measured by T. H. PARKER. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 2 2 2 1 1 2 1 54-7652 53-9794 53-1334 48-7862 47-4588 4V 9683 45 2930 45-2278 2 43-5520 9574 0124 -14-27 2 1 2 1 1 2 37-9742 37-2646 30-8961 30 8566 27-4200 27-2709 249(i 0402 38-55 4418 9533 0286 0307 30-60 32'29 8346 3950 (1420 0176 37-71 -15-27 2128 0259 27-03 \Veighted Radial vel S AQUIL.-E 17f 1!W8. July 31. G. M. T. 17' 1 17 m mean 26 25 7 61 12 28 34 2 RPKR. KKK. V a Vd Curvature ocity _ >4 * Observed by W. E. HA Measured by T. H. PAB Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. Mean Wt. of | Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. 2 1 2 2 2 54-7189 53-9370 53-0930 52-3557 48-7477 48-6932 47-4122 45-2530 1 2 * 2 1 i 2 45-1899 44 : 2025 43-5112 37-9405 37 2294 27-3766 27-2349 2129 2255 0258 0337 26 93 34-81 9575 0123 -14-15 3772 0376 42-52 2504 3883 0384 0240 36-82 -20-84 7212 4352 0428 0352 46-48 37-66 1 " " Weighted Radial vel mean 36 05 7-61 12 28 44 V a V -22 31 !i7N4 0086 + 9-89 7924 0392 -39 43 : 4a6s 0155 + 17-58 3779 03(11 -31 33 730,1 ^0279 -30-29 1 Weight Radial c d mean -19 il 7 19 >8 V .. - 9 Va Curvatui elfn-'itv . e _ -29-7 1908. Aug. 15. (i. M. T. 17 h 38 m 3 AQUIL^E 1783. Observed by J. S. PLASKETT. Measured by T. H. PARKER. 1 Mean Wt. of S.-ttings. Corrected Star Settings. Displace- ment in Revolutioi s. Velocity. Wt. Mean of Settings. Corrected Star Settings. Displace- ment in Revolutions. Velocity. > 57 812(5 2 45-2802 1 57 8193 ' 54-7335 8023 0245 -29 49 1 & 45-2457 44 2265 2404 2205 - 0020 0387 + 2-08 -39 97 1 53 ' 9473 '573 '0125 14-38 T 43-5434 9 53'0995 1 41 3061 2951 0021 2 10 i 52-4002 o 52 2469 4072 0076 8-58 s 40-5358 37 9743 5258 0021 2-08 i 51-7060 i " 40 X4fi7 7120 '3487 0455 '0213 51-05 23'25 1 2 37-2659 30 - 9025 2499 0389 37 30 1 48 '7663 1 29 8983 8643 0105 9 31 i 48-7345 1 ,17 4 ^*N 7300 4828 0280 '0124 -30-38 + 13 '26 i 2 27-4506 27 -2858 4116 0010 - o-w; A 45 9813 9773 0073 - 7-67 Weighted mean V a V* Curvature . Radial velocity. , -29'2 554 DEPARTMENT OF THE INTERIOR 9-10 EDWARD VII., A. 1910 1908. Aug. 27. G. M. T. 15 h 03" S AQUIL^E 1837- Observed by J. B. CANNON. Measured by T. H. PARKER. Mean Corrected Displace- Mean Corrected Displace- \Vt. of Star ment in Velocity. Wt. of Star ment in Velocity. Settings. Settings. Revolutions. Settings. Settings. Revolutions. 2 73 0183 2 45-2880 i 72 8513 8430 0218 -31 63 1 45-2372 2232 0155 -16'18 2 72-4532 1 44'239f, 2264 0328 - 33 91 2 59 '81 29 2 43-5517 1 57-8288 8283 0015 + 1 80 . 1 41 8079 7949 0367 :!(-,! \-> 2 54 ' 7500 1 37-9771 1 63-9747 9667 0031 - 3 56 1 37-3070 2925 0037 t I'.'M 2 53'1197 *> so 9079 5 51-7273 7173 0402 -45 10 i 30-8756 8386 0370 3:', -22 2 48-7819 30 4141 P.751 0878 - :i2 f.f> 1 47-4976 4846 0142 + 15-19 2 30-2857 i 46 0043 9915 IM)41 + 4 31 Weighted mean L't> '.<". V -18-18 V rf . .. . '09 Curvature . - '28 Radial velocity -39'5 THIS BOOK IS DUE ON THE LAST DATE STAMPED BELOW AN INITIAL FINE OF 25 CENTS WILL BE ASSESSED FOR FAILURE TO RETURN THIS BOOK ON THE DATE DUE. THE PENALTY WILL INCREASE TO SO CENTS ON THE FOURTH DAY AND TO $1.OO ON THE SEVENTH DAY OVERDUE. $F 2o igj, LD 21-95m-7,'37 738385 UNIVERSITY OF CALIFORNIA LIBRARY