GIFT or c. .* 4- Astr-onoialcal Society of the Pacific AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS BY WALTER S. ADAMS ASSISTED BY JENNIE B. LASBY L? 8R ARY Or TVJS ASTRONOMICAL SOCIETY OF THE PACIFIC WASHINGTON, D. C. PUBLISHED BY THE CARNEGIE INSTITUTION OF WASHINGTON 191 1 At^w';".- 5 st J-c c c'' CARNEGIE INSTITUTION OF WASHINGTON PUBLICATION No. 138 PAPERS OF THE MOUNT WILSON SOLAR OBSERVATORY, VOL. I, PART I UEOKOE E. HALE, Director AblRONOMY DIPT. Xortuootj J. 8. Gushing Co. Berwick & Smith Co. Norwood, Mass., U. 8. A. TABLE OF CONTENTS. PAGE INTRODUCTION I OBSERVATIONS AND METHODS OF REDUCTION. 1. OBSERVATIONS OK 1906-1907 3 2. RECORD OF OBSERVATIONS, 1906-1907 6 3. METHODS OF MEASUREMENT AND REDUCTION u 4. SOURCES OF ERROR 13 5. RESULTS FOR THE INDIVIDUAL PLATES, 1906-1907 15 6. OBSERVATIONS OF 1908 59 7. RECORD OF OBSERVATIONS, 1908 62 8. RESULTS FOR THE INDIVIDUAL PLATES, 1908 66 9. SPECIAL OBSERVATIONS ON THE a LINE OF HYDROGEN 103 10. SPECIAL OBSERVATIONS ON X 4227 OF CALCIUM 107 DISCUSSION OF THE RESULTS. n. SYSTEMATIC DEVIATIONS OF VELOCITY OF ROTATION DERIVED FROM VARIOUS LINES OF THE REVERSING LAYER 109 12. INCREASE OF DEVIATIONS IN HIGHER LATITUDES ui 13. MEAN RESULTS FOR THE REVERSING LAYER. - VARIABILITY OF THE SOLAR ROTATION. COMPARISON OF RE- SULTS WITH THOSE OF OTHER OBSERVERS 112 14. PROBABLE ERRORS 117 15. COMPARISON OF RESULTS FOR SUN-SPOTS, FACUIJE, FLOCCULI, REVERSING LAYER, THE a LINE OF HYDROGEN AND X 4227 OF CALCIUM 118 16. A CASE OF LARGE PROPER MOTION IN THE REVERSING LAYER 122 17. DETERMINATION OF THE SOLAR ROTATION WITH THE a LINE OF HYDROGEN 126 18. DETERMINATION OF THE SOLAR ROTATION WITH X 4227 OF CALCIUM 127 19. COMPARISON OF RESULTS FROM ALL THE LINES INVESTIGATED 129 20. GENERAL SUMMARY 130 BIBLIOGRAPHICAL REFERENCES 132 iii INTRODUCTION. ONE of the earliest of the applications of the Doppler-Fizeau principle in astrophysics was to the prob- lem of the rotation of the sun. The detection of the minute displacements of the spectrum lines at the sun's limb by Vogel in 1871 (>)* not only furnished an invaluable proof of the validity of the principle, but also indicated the possibility of obtaining, with the aid of more powerful apparatus, a measure of the rate of rotation by an independent method free from many of the difficulties possessed by such methods as depend upon direct observations of the solar surface. The invention of the diffraction grating made it possible to apply to the study of the solar spectrum spectroscopes of much greater power than any previously available, and with its aid Young in 1876 (2) was able to measure the displacements of the spectrum lines at the sun's equator with a considerable degree of accuracy, and to show that the results so obtained were in satisfactory agreement with those derived from observations of the sun-spots. Shortly after, Langley (3) and Cornu (4) made an interesting application of the principle by showing how lines due to the earth's atmosphere may at once be distinguished from those of solar origin by their freedom from displacement when the spectra of the opposite edges of the sun are observed simultaneously. In 1888 Duner began at Upsala his celebrated investigation of the rotation of the sun (s). This work, continued throughout 1889 and 1890 and repeated in the years 1901 to 1903, is without doubt the standard of reference among those who have since undertaken the study of this problem. Duner in this investiga- tion made use of the suggestion by Langley already mentioned, and by employing atmospheric lines as his standards of reference was enabled to make all of his measures differential, and so to attain an extraor- dinarily high degree of precision. His determinations are grouped about points separated by intervals of 15 between the solar equator and 75 of heliographic latitude, a point far beyond the limit reached in sun-spot observations. With the aid of these results he was able to discuss exhaustively the validity of the various formulae connecting the rotation period with the latitude proposed by Carrington, Faye, and Spoerer as the result of their observations of sun-spots between the equator and 45 of latitude. From this discussion he concluded that Faye's formula most closely represented his independent observations in the higher latitudes. Many references will be made to this memoir of Duner in the following pages. Following Duner's earlier work some photographic observations were made by Jewell at Baltimore (6), but no details of the results obtained by him have been published. In 1887 Crew (?) also took up the prob- lem and obtained a series of values differing widely from those of Duner. It seems probable that some source of systematic error was present in these observations, a possible cause, as Crew himself suggested, being that arising from displacements of the slit due to heating by the sun's image. The most recent investigation was that made by Halm at Edinburgh (8) during the years 1903 to 1906, and led to results of the highest accuracy and importance. Like Duner, Halm made use of the differential method, and since the lines employed by him are the same as those of Duner, the two series of results are strictly comparable. In two essential features the instruments used by Halm differ from those of most previous investigators. The first was in the use of a heliometer to form the solar image, it being possible by movement of the divided object-glass to pass rapidly from one extremity of the solar diameter to the other. The second was in the employment of a fixed horizontal spectroscope in place of an instrument attached to an equatorial telescope and moving with it. The advantages of such a type of spectroscope can hardly be questioned, and it was probably mainly due to this cause that Halm's observations showed * Numbers in parenthesis indicate references to literature on p. 133. INTRODUCTION. % c' c' ' ' ' ^" c ' such a high degree of internal agreement, the probable errors being only about one-half of those of Duner. It was as a result of these observations that Halm concluded a variable period of rotation for the sun, his determinations for separate years showing large systematic deviations from each other. In a final paper on the subject (9) he also discussed the later observations of Duner and arrived at the conclusion that these, like his own, gave evidence of a periodic variation in the sun's rate of rotation. The importance of the question thus raised can hardly be overestimated, and it will perhaps be the main consideration in future investigations of this problem. All of the preceding determinations of the rotation period of the sun, with the exception of that of Jewell, have been based on visual observations. While it is probable that the photographic method does not possess tor such an investigation the overwhelming advantages which it has in the case of faint and difficult spectra, it has certain points of superiority which render an independent determination by its aid of the greatest value. Two of these are especially important. The visual determinations have been based upon a very limited number of lines in the less refrangible part of the spectrum. With the photo- graphic method it is possible to employ a much larger number of lines and to utilize the more refrangible part of the spectrum where the lines are more numerous and the variety of elements which can be employed correspondingly greater. These facts were fully realized at the time of the establishment of the Mount Wilson Solar Observatory, and plans were made for taking up a photographic investigation of the rotation period of the sun as soon as suitable instrumental equipment was ready. With the completion of the Snow telescope, and the powerful i8-foot spectrograph used in conjunction with it, a combination of apparatus admirably adapted for the work was available, and accordingly in the spring of 1906 the first observations were begun. These were continued until June, 1907, after which all observational work on the rotation of the sun was transferred to the tower telescope. Since the investigation was commenced five series of observations have been made and are discussed in the pages which follow. Two of these deal with lines selected from the spectrum of the general reversing layer, two with the a line of hydrogen, and the fifth with X 4227 of calcium. The lines of hydrogen and calcium give results differing widely from those obtained for the reversing layer, and so, of course, should be treated individually. Moreover, since the two series of determinations for the reversing layer are separated by a considerable interval of time, and the apparatus employed in the second series was entirely different from that in the first, it seems desirable to treat them separately in the present discussion. Brief accounts of the main results of these two series of observations have already been published, the first in 1907 (10) and the second in 1909 (n). A detailed account of the observations and reductions follows in Sections i-io. The discussion and comparison of the results will be considered in Sections 1 1-20. OBSERVATIONS AND METHODS OF REDUCTION. i. OBSERVATIONS OF 1906-1907. THE Snow telescope consists of a ccelostat mirror of 30 inches (76.2 cm) diameter mounted equatorially, which throws a beam of light upon a second plane mirror 24 inches (61.0 cm) in diameter mounted south of it. From this in turn the light passes to a concave mirror of 24 inches aperture and 60 feet (18.3 m) focal length placed at the north end of the telescope house. All of the mirrors are mounted upon masonry piers and are supplied with slow motions, so that the illumination of the concave mirror may be controlled from the ccelostat and the position of the image varied according to the instrument with which it is to be used. The direction of the beam from the second plane mirror to the concave mirror is not horizontal but is inclined at an angle of 5, owing to the nature of the ground on which the building is placed. For a similar reason the track upon which the second mirror mounting moves does not point north and south but at an angle of 15 to this direction. The ccelostat mirror may be moved east and west upon a track and the second plane mirror north and south (more accurately northeast and southwest) in order to provide for the variation in the sun's declination. The concave mirror can be moved along the direction of the optical axis to allow for focusing of the solar image, and by simple rotation of the mirror the image may be thrown upon any instrument desired. The image formed by the concave mirror has a mean diameter of 6.7 inches (17.0 cm). The 1 8-foot (5.5 m) spectrograph used in this investigation and for many other spectrum studies as well, in particular that of the spectra of sun-spots, is placed about 18 inches (45.7 cm) to one side of the optical axis and about 12 inches (30.5 cm) above it, its tube lying directly above the 5-foot spectroheliograph. It is of the Littrow, or auto-collimating, type, with a lens 4 inches (10.2 cm) in diameter used with a plane grating of the same aperture. Both lens and grating are supported on a cast-iron base. The lens is focused by a screw and moves in ways parallel to the optical axis, and may be clamped in any desired position. The grating is mounted in the face of a metal box which rests upon a rotating table, its position being defined by four screws which touch its surface lightly. The original purpose of the metal box was to provide for temperature control, if needed, but in the present investigation the exposures have been so short as to render this unnecessary. Reflections from the surface of the lens are prevented from reaching the plate by a narrow bar placed across the lens, and in addition a system of diaphragms is provided along the tube of the spectrograph. This tube is of wood covered with sheet iron and its central section immediately over the spectroheliograph can be rotated out of place in order to give free access to the prism box of the latter instrument. The slit and plate-holder are carried by a single large casting, the base of which rests on a masonry pier. The distance between the center of the slit and the center of the plate-holder opening is about 3 inches (7.6 cm), an amount too small to introduce any appreciable astigmatism into the spectrum lines. The plate- holder may be moved up and down by a rack-and-pinion in order to provide for taking several exposures on the same relate. In front of the spectrograph and about 6 inches (15.2 cm) below the slit is a large cast-iron bracket which serves to support the various auxiliary attachments used in conjunction with the spectrograph. The marked advantages to be derived from photographing the opposite edges of the sun simultaneously, and so doubling the displacements to be observed, led to the employment of a modified form of the device first suggested by Langley. A brass casting with a circular opening about 7 inches (17.8 cm) in diameter carries two brass arms, each of which forms a radius of this opening and rotates about its center. On the outer end of each arm is mounted a small diagonal prism, its mean distance from the center of rotation 3 4 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. corresponding to the mean radius of the sun's image. These prisms are capable of adjustment toward and away from the center in order to allow for variations in the diameter of the sun. At the inner ends of the brass arms and immediately in front of the slit are two other diagonal prisms which receive the beams of light from the first pair. These prisms taper at the end to a width of 0.5 mm, and are mounted with their edges about 0.25 mm apart. The latter distance, accordingly, represents the separation on the photo- graphs of the spectra of the two opposite edges of the sun. At the outer ends of the arms are pointers by means of which readings are made upon a silvered circle concentric with the opening in the brass casting and graduated to half degrees. The whole apparatus is mounted upon the cast-iron bracket already referred to, and its position with reference to the slit is accurately defined by two taper pins which enter the bracket. The grating which has been used throughout this investigation is one of the earlier Rowland gratings, with ruled surface 3.25 by 1.75 inches (8.3x4.4 cm), and has 14,438 lines to the inch (570 lines to the millimeter). The spectra in the second, third, and fourth orders on one side of the normal are exception- ally bright and the definition is excellent, in spite of the great focal length of the spectrograph. For all of the work on the rotation of the sun with this spectrograph the fourth order has been used, the great linear scale thus obtained being of the utmost value. In this order, at X 4200, i mm = 0.71 Angstrom. The importance of accurate adjustment of the spectrograph in a study of small displacements can not be too highly emphasized. In the present investigation the greatest care has had to be taken to guard against unequal illumination of the collimating lens and grating surface by the light from the opposite edges of the sun. It is evident that a small change in the position of the diagonal prisms near the slit would affect this illumination most seriously. Accordingly, before each exposure it has been my practice to occult the images of the two edges in succession and to examine the character of the illumination from each edge. The accuracy of this test has been examined photographically and it has been found to be capable of giving good results when the slit is narrow and the illumination is fairly weak. In addition to this a valuable check upon the accuracy of the adjustment is furnished by the relative density of the pair of spectra on the photographic plates, and no plates have been included in the series used for measurement in which there is any marked difference in the intensity of the spectra of the two edges of the sun. A comparison of the ratio of aperture to focal length in the case of telescope and spectrograph shows that provided the adjustment is reasonably accurate the margin of safety for full illumination of the grating is considerable. In the case of the telescope the ratio is i : 30, while in that of the spectrograph for the full aperture of the collimating lens it is i : 54, or, for the surface of the grating actually employed, about i : 72. A brief description of the actual procedure followed in taking the plates may be of value. The auxiliary diagonal prism apparatus is placed in position in front of the spectrograph and the image of the sun cen- tered upon it and focused on the slit. The image is then slightly displaced by rotation of the ccelostat mirror, the clock stopped, and the points of transit observed of a spot or other well-defined object on' the solar disk across the position circle. Usually several sets of readings have been made and a mean taken. Since the orientation of the image with this form of coelostat mounting depends upon the position of the second plane mirror on its track as well as upon that of the ccelostat carriage, these observations for a line of reference have been made before each series of plates, and in most cases repeated after the series, espe- cially if the interval covered is at all long. Occasionally the transits have been obtained by rotation of the ccelostat mirror by means of its slow motion, and comparison with the values secured when the image is allowed to drift shows that there is little choice between the two methods. The range of several such determinations usually amounts to about o?2 or o?3- With the aid of these observations the east-and-west reference line is found and the position of the sun's pole and equator is then readily computed from an auxiliary table, such, for example, as is given in the Companion to the Observatory. As soon as the position of the sun's equator is known, the diagonal prisms are set for the latitude desired, the illumination of the grating is examined, and the exposure taken. The second setting upon the position circle is then made and the process repeated. Usually six exposures have been taken upon each plate, although the number OBSERVATIONS OF 1906-1907. varies according to the latitudes employed. In general, I have used the same plan as that adopted by Duner of taking points 15 apart between o and 75 of latitude, but some intermediate points have also been added, particularly in the higher latitudes when the orientation of the image was especially favorable. In selecting the region of the spectrum to be employed several considerations have been borne in mind. The use of photographic plates and the desirability of keeping the exposure times as short as possible in order to avoid heating of the slit jaws, as well as changes of focus and astigmatism of the solar image due to changes in the figure of the mirrors arising from prolonged exposure to the sun's heat, naturally led to the employment of the more refrangible part of the spectrum. The fact that the observations of Duner and Halm were obtained in the less refrangible part also made the use of an independent region most desirable. Although the displacement of the spectrum lines for a given radial velocity is proportional to wave-length and consequently smaller in the violet part of the spectrum than in the red, this disadvantage is fully counteracted by the possibility of employing higher dispersion and fine-grained photographic plates to procure greater linear scale and higher resolution. The plates finally used were Seed's "Process" plates, which give excellent contrast and are appreciably more rapid than lantern-slide plates in the violet part of the spectrum. A second consideration which led to the selection of a region in the violet was the neces- sity of obtaining the lines of a sufficient variety of elements within the range of wave-length such as could be secured on a single plate. After considerable examination the part of the spectrum between X 4200 and \ 4300 was selected. The plates employed are very sensitive to this region, and within its limits are found an immense number of lines including a part of the G group, as well as the head of the first violet cyanogen fluting. The presence of the so-called "blue line" of calcium at X 4227 has also proved of great value in the later observations. The list of lines finally adopted is given in Table i. The wave-lengths, intensities, and identifications are from Rowland's table. TABLE i. LINES OBSERVED IN 1906-1907. X ELEMENT. INTENSITY. BEHAVIOR AT LIMB. 4196.699 La 2 Much weakened. 4197-257 CN 2 Slightly weakened. 4203.730 Cr 2 Strengthened and widened. 4209.144 Zr i Weakened. 4216.136 CN i Weakened. 4220.509 Fe 3 Slightly strengthened and widened. 4232.887 Fe 2 Much strengthened and widened. 4257.815 Mn 2 Slightly strengthened and widened. 4258-477 Fe 2 Much strengthened and widened. 4265.418 Fe 2 Slightly weakened. 4266.081 Mn 2 Slightly weakened. 4268.915 Fc 2 Slightly weakened. 4276.836 - Zr 2 Weakened. 4284.838 Ni I Slightly weakened. 4287.566 Ti I Slightly strengthened and widened. 4288.310 Ti, Fe I Widened. 4290.377 Ti 2 Slightly weakened. Enhanced line of Ti. 4290.542 Fe I Slightly weakened. 4291.630 Fe 2 Much strengthened. 4294.936 Zr 2 Probably weakened. The reasons for the selection of the lines in the above list are for the most part self-evident. The lines of cyanogen are included because of the low level at which carbon, and presumably its compounds, lie in the sun's atmosphere, if we may judge from chromospheric observations. The line of lanthanum was selected because of the high atomic weight of this element, and the consequent presumption for a relatively low level, 6 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. and the same reason holds in lesser degree for zirconium. Iron is represented by seven lines in the list, a number sufficient to eliminate to a great extent possible peculiarities among individual lines when a mean value is taken. Titanium is of great interest because of its relatively high level in the chromospheric spectrum, and a larger number of lines would have been desirable in its case. The necessity, however, for selecting the lines best suited for measurement, and free from close neighboring lines, has limited the num- ber to three. Of these X 4290.377 is an enhanced line, that is, relatively stronger in the spark spectrum than in that of the arc. The other lines belong to elements having an atomic weight close to that of iron. The last column in Table i gives the behavior of the lines at the limb of the sun as compared with the center. At the time at which the list was selected these remarkable differences in intensity and appear- ance were not known (12). It was noted on the earliest plates, however, that the lines at the limb as a rule were decidedly broader and more diffuse, as well as in most cases somewhat weaker, than the lines of the ordinary solar spectrum in this region. At first this was thought to be due to some instrumental cause, possibly the long path traversed by the light through the glass of the diagonal prisms, but the discovery soon afterward, by Mr. Hale and myself, of the essential differences in character of the spectrum of the sun's limb fully explained the difficulty. In view of this relative diffuseness of the lines in the immediate neigh- borhood of the edge of the sun, it seems to me probable that a slightly higher degree of accuracy might be attained in future observations by taking the light from a point somewhat farther within the disk than that which is usually employed, and applying the small corrections needed to reduce to the sun's edge. Observations have shown that the spectrum of the limb reverts to the normal solar spectrum very rapidly as the slit is moved away from the sun's edge, and the gain in the sharpness of the lines would probably more than compensate for the small difference in the size of the displacements measured. An accurate knowledge of the distance of the slit from the limb would, of course, be essential. 2. RECORD OF OBSERVATIONS, 1906-1907. The series of plates employed in this investigation, numbering 44, began in May, 1906, and extended to June, 1907. Between July and October, 1906, no plates were taken, but with the exception of this interval the period is fairly well covered. The plates used do not include all which were taken, but careful selection was made with special regard to quality and the conditions under which they were obtained. Halm has called attention to the importance of the transparency of the sky in such observations, the effect of a hazy sky, or light cloudiness, being to superpose the spectrum of skylight upon the spectrum from the edge of the sun, and consequently to make the displacements measured systematically too small. This point was usually tested visually in the same way as was done by Halm, and a few quantitative determinations of the effect were also made from photographs obtained at a time when the sky was particularly hazy. The record of the observations contained in Table 2 gives the data for the individual plates. The estimates of the definition in the fourth column are on a scale of 10. The column headed "Scale concave mirror" refers to the setting of the concave mirror mounting upon its track and is read upon an arbitrary scale. Positive readings indicate a direction north from zero, or a greater distance between mirror and slit. The considerable variations in these readings are due to the change of figure of the system of mirrors, par- ticularly of the ccelostat mirror, when exposed to the sun's heat. This change is dependent upon a variety of conditions, especially the state of the silver surfaces of the mirrors and the temperature of the air sur- rounding them. The column headed "Observations for zero" gives the readings of the points of transit across the position circle of definite points on the sun's disk. The method of observing these has been ex- plained previously. The readings of the position circle refer to the settings of the pair of diagonal prisms, and it is from these settings that the latitudes of the observed points on the sun's edge are calculated. The numbers following the words "ccelostat" and "second flat" in the column of remarks indicate the positions of these mirrors on their respective tracks. The orientation of the sun's image of course is dependent upon these quantities. RECORD OF OBSERVATIONS, 1906-1907. TABLE 2. RECORD OF OBSERVATIONS, 1906-1007. DATE. HOUR G. M.T. PLATE No. DEFINITION.! EX- POSURE TIME. SLIT WIDTH. SCALE CONCAVE MIRROR. OBSERVATIONS FOR ZERO. EXPOSURE. 1 READ- INGS POSITION CIRCLE. REMARKS. 1906 h m sec mm May 3 7 3 <" 3 2 240 0.025 + 10 80.2-299.3 i 219.2 Zero very difficult on account of 80.3-300.0 2 234.2 definition. 94.7-286.O 3 249-2 95.1-285.0 4 264.2 96.1-284.7 5 279.2 6 294.2 May8 6 o 01 6 4 250 0.025 -18 114.5-267.5 i 293.2 96.1-286.5 2 278.2 II4.5-266.8 3 263.2 95.6-286.5 4 248.2 5 233.2 6 218.2 May 19 10 30 a 8 5 125 0.025 +252 IOI.5-28I.O i 302.0 Ccelostat 200. IOI.7-280.5 2 297.0 Second Flat 600. 3 285.7 Mirrors resilvered. 4 270.7 Prisms cleaned. 5 255-7 Bars interfere with windows at 6 242.0 300 and at 240. 7 225.7 June 12 6 45 ia 19 5 45 0.030 + 200 100.6-286.0 i 210.3 100.3-286.0 2 234-3 IO2.2-284.2 3 249-3 IO4.O-282.5 4 264.3 103.6-282.7 5 279-3 6 294-3 June 12 7 1 S w 20 5 60 O.O3O + 2OO i 2IQ ? *'"O W 2 *y p o 234.3 3 249-3 4 264.3 5 279-3 6 294-3 June 12 7 45 fe> 21 5 60 0.030 + 3OO i 204. ^ 2 y*t-o 278.3 3 279-3 4 264-3 5 249-3 6 234-3 7 219.3 June 15 6 o u 23 4 65 0.030 + I?0 102.3-283.8 i 293.0 Ccelostat 300. 103.0-283.2 2 278.0 Second Flat 800. 88.5-298.0 3 263.0 4 248.0 5 233-0 6 218.0 June 15 6 IS u> 24 3 65 0.030 + 1^0 i 218.0 i *j v 2 233.0 3 248.0 4 263.0 5 278.0 6 293.0 June 15 6 35 u 25 3 65 O.O3O + 1 SO i 20^.0 o 1 *o w 2 *yo* v 278.0 3 263.0 4 248.0 5 233.0 6 218.0 June 16 6 20 w 26 4 65 0.030 +90 102.3-285.3 i 294.7 Ccelostat 400. 105.7-284.5 2 279.7 Second Flat 870. 105.7-284.7 3 264.7 4 249.7 5 234-7 6 219.7 8 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE 2. RECORD OF OBSERVATIONS, 1906-1907 Continued. DATE. HOUR G.M.T. PLATE No. DEFINITION. 1 EX- POSURE TIME. SLIT WIDTH. SCALE CONCAVE MIRROR. OBSERVATIONS FOR ZERO. EXPOSURE. 1 READ- INGS POSITION CIRCLE. REMARKS. 1906 h m sec mm June 1 6 7 5 w 27 3 6? O.O^O +90 i 2O4..7 J W * W O I v v 2 **yr- / 279-7 3 264.7 4 249.7 5 234-7 6 219.7 Oct. 19 II IO w 30 2-3 75 0.030 +260 83.0-293.0 i 72.0 Angles reckoned from B readings 82.8-293.3 2 87.0 on west side position circle. 82.5-294.0 3 IO2.O Ccelostat 112. 4 II7.0 Second Flat 300. 5 132.0 6 147.0 Oct. 19 12 IO w 31 2-3 90 0.032 +266 i I47.O W*VJ* 2 J t / - v 132.0 3 II7.0 4 102.0 5 87.0 6 72.0 Nov. n 10 W 35 4 45 0.032 -1-400 83-5-275-0 i I4I.7 83-3-275-3 2 66.7 Zero observations at 6 h o m . Nov. ii 10 15 36 4 CO O.O3O +400 I 66.7 Distance between windows chanced o .rf.VJV 2 \t\ft i 81.7 to 165.1 mm; between inside 3 96.7 edges 83.55 mm. 4 111.7 5 126.7 6 141.7 Nov. ii 10 40 41 5 7 0.025 + 140 i 124. C 2 * **+ J 109.5 3 94-S 4 94-S 5 109.5 6 124-5 RECORD OF OBSERVATIONS, 1906-1907. TABLE 2. RECORD or OBSERVATIONS, 1906-1907 Continued. DATE. HOUR G.M.T. PLATE No. I'NOIIINIiaQ EX- POSURE TIME. SLIT WIDTH. SCALE CONCAVE MIRROR. OBSERVATIONS FOR ZERO. V) READ- INGS POSITION CIRCLE. REMARKS. igo6 h m sec mm Dec. 18 TO 7Q w 46 6e O.O3O -4-1 co I I4I.O AW JW if.V V O *" V O'-' 1 * o v 2 I26.O 3 126.0 4 I4I.O 5 I4I.O 6 126.0 Dec. 18 10 50 w 47 4 70 0.030 + 150 78.0-282.5 i 126.0 78.3-282.7 2 I4I.O 102.5-258.5 3 I33-S 102.0-258.5 4 II7.O 5 II7.0 6 133-5 1907 Feb. 3 5 40 w 50 3~4 70 0.030 + 22O 105.6-289.5 I 221. Zero observations at 4 h 40. 98.6-296.5 2 230.0 101.7-293.5 3 246.0 102.8-292.3 4 262.0 S 277.0 6 293.0 Feb. 15 5 4 <"55 4 60 0.030 + 160 101.0-293.3 4 266.0 Zero observations at s h o m . 95.5-298.5 5 282.0 93.3-300.5 6 297.0 94.0-300.3 96.5-298.0 101.5-292.3 Feb. 15 6 5 w 56 4 55 0.030 + 180 94-3- 99-5 I 218.0 95.0- 99.2 2 234-0 3 250.0 4 266.0 S 282.0 6 297.0 Feb. 28 7 '5 w 60 24. 60 0.030 -(-250 i 3O2.O O T 1 2 O 302.0 3 288.0 4 280.3 S 273-3 6 264.5 7 257.5 Feb. 28 7 4 u 61 3-4 60 0.030 +250 97.0-297.3 i 248.3 Zero observations at 7 h 55. 82.0-312.3 2 242.3 102.3-291.6 3 242.3 I35-7-259-3 4 248-3 S 257.5 6 264.5 Feb. 28 9 15 w 62 3 65 0.030 + 250 70.5-298.5 i 302.0 Zero observations at 9 h 30"". 70.7-298.3 2 288.0 91.0-278.5 3 280.3 123.5-246.0 4 273.3 5 265.5 6 257.5 Feb. 28 9 45 lM> 63 a 65 0.030 + 250 i 251.8 o 2 244.8 3 260.6 4 267.6 S 275.2 6 288.8 April 7 3 20 u 64 5 90 0.030 + 180 96.3-299.0 3 235.0 Zero observations at o h io m . 99.5-295.7 Mirrors badly tarnished. 105.3-289.7 93.0-302.2 105.7-289.5 10 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE 2. RECORD or OBSERVATIONS, 1906-1907 Continued. DATE. HOUR G M.T. PLATE No. DEFINITION. 1 EX- POSURE TIME. SLIT WIDTH. SCALE CONCAVE MIRROR. OBSERVATIONS FOR ZERO. EXPOSURE. 1 READ- INGS POSITION CIRCLE. REMARKS. 1907 h m sec mm April 7 5 45 <> 67 IOO O O3O 4-T CO 3 2 T r r April 7 6 45 * \J f co 68 ? IOO o.o^o i * j** o 6 235.5 April 7 7 IO w 60 o 1 IOO ^'"O O.O3O 4-i CO i 235.5 April 22 / 8 20 *_ = cos (p P) cos D The polar distance IT is, of course, the complement of the angle <. 4. SOURCES OF ERROR. As in all quantitative investigations of the displacements of spectrum lines, the errors in the results obtained in the present study naturally fall under two heads. Under the first are those due to instrumental causes, leading to errors in the values of the displacements on the plates. Under the second fall errors arising from the measurement of the plates and the reduction of the results obtained. There can be little doubt that of these two the first is by far the more serious, since errors of this sort are much more liable to be of a systematic character than those arising from either measurement or reduction. The principal sources of error to be considered under the first head are as follows : (1) Astigmatism, changes of focus, and lack of definition of the solar image. (2) Heating of the slit jaws during exposures. (3) Unequal illumination of the grating from the opposite edges of the sun. (4) The presence of the spectrum of skylight, which tends to reduce the values of the displacements observed. I have already discussed (3) and (4) in a preceding paragraph and described the precautions taken to avoid the introduction of error from them. It seems probable that any difficulty due to the presence of the skylight spectrum can hardly be appreciable when the plates used for measurement have been selected 14 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. from those taken on especially transparent days. Experiments made by Mr. Hale and myself (13) have indicated that on a day of average transparency on Mount Wilson the brightness of the sky spectrum close to the edge of the sun is about one-fortieth that of the spectrum inside the limb. Accordingly, this would represent about the maximum effect in the case of the plates under consideration, and a contribution of one-fortieth to the intensity of the spectrum lines would probably be entirely inappreciable both in the appearance of the plates and in the measurement. The influence of inequalities in the illumination of the grating can probably never be absolutely eliminated, but with the aid of the precautions taken in securing the exposures I feel confident that the effect has been reduced to a minimum, and that in an extended series of observations the residual effect can be regarded mainly as an accidental error which will tend to eliminate itself with a sufficient number of plates. The question of the heating of the slit jaws during the exposures has been treated with especial care, since errors arising from this source have been encountered by other observers. On account of the com- paratively small ratio of i : 30 between aperture and focal length in the Snow telescope, and the relatively large image employed, the amount of heat which falls upon the slit is of course much less than in the case of relatively short focus telescopes. Additional advantages are the silvering of the slit jaws, which helps to reflect the heat that falls upon them, and the fact that a length of only about 3 mm of the slit is exposed to the sun when the plate is taken. In order to obtain a definite test, however, I have tried several exposures upon the same part of the sun, using a comparison spectrum obtained with and without the interposition of a glass cell containing a thickness of 20 mm of water. Such a screen could hardly fail practically to eliminate heat effects on the slit. The measurement of these plates has indicated no difference whatsoever between the results obtained with and without the screen, and the conclusion seems to be warranted that any effect upon the rotation values due to heating of the slit jaws during the exposures must be very small. The first source of error referred to in the list, which has to do with the astigmatism and lack of definition of the sun's image upon the slit of the spectrograph, is perhaps the most serious of any encountered in the investigation. In working with the Snow telescope we have found that the definition of the solar image toward the middle of the day is much inferior to what it is in the early morning and late afternoon, and that the effect of prolonged exposure of the mirrors to sunlight at this time of day is to introduce a consid- erable amount of astigmatism due to changes of figure of the plane mirrors. This shows itself in a distortion of the image and a difference of focus between the vertical and horizontal diameters. The effect of this upon determinations of rotation is to introduce into the slit additional light from points differing slightly in latitude from those upon which the diagonal prisms are set, and also to cause a slight difference for different latitudes in the distance from the sun's edge at which the light is taken. The first is probably much the more serious. The effect of changes of focus during the exposures is also in the direction of bringing into the slit scattered light from other latitudes than those upon which the instrument is set, and the same holds true of most defects in the character of the sun's image. Since the plates for the determination of the rotation of the sun have been taken for the most part toward the middle of the day, the early morning hours and the late afternoon being utilized for the spec- troheliograph, the effects discussed here must have influenced the results obtained to a certain extent. The selection of the plates to be used for measurement, however, and the rejection of those which were obtained under especially unfavorable conditions, must have rendered decidedly less the amount of the error from this source which can enter into the determinations. In taking the plates it has been found possible to reduce materially the amount of astigmatism and variation of focus by keeping the mirrors cooled by a circulation of air about them from electric fans, and by shutting off the sunlight for short inter- vals between the successive exposures on the plate. It is evident that even in the case of a poorly defined image the main effect of the introduction into the slit of the scattered light from points bordering on the latitudes employed will be to widen the lines without altering the displacements seriously, since in general the foreign light will come from regions distributed symmetrically about these points of latitude. In the RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907. 15 case, however, of a marked change in the character of the image during the exposures on the various lati- tudes, systematic errors might be introduced, and such effects would naturally be greater in the higher latitudes, where the change of velocity with the latitude is more rapid than it is near the equator. It is of course impossible to say to what extent these effects may have entered, and I can only emphasize the fact that all the precautions which have seemed feasible have been taken to keep the character of the image the same during the series of exposures. A consideration of the second class of errors which may influence these results, those that arise from errors of measurement and reduction, may be passed over rapidly. The methods of measurement and the screw errors affecting the instruments employed have already been discussed in full, and it seems probable that there can be but little systematic error due to this source affecting the results. In the reductions, moreover, methods rigorous within the limits of accuracy required have been followed, and consequently there is little to be feared from this source except as regards numerical errors of computation. To avoid the latter a considerable part of the work has been done in duplicate, especially that involving the various cor- rections to the observed velocities and the computation of the latitudes. The conversion of the measured displacements into velocities is readily checked by comparison with a standard table. In conclusion it should be noted that small absolute errors may be introduced into the results by uncertainty in the values of the constants of reduction employed. Throughout the observations of 1906-1907 the following values, by Carrington, of the inclination of the sun's equator / and the longitude of its ascending node ^ have been used. i = fi 5 ' = 74 24' (1906) In concluding this discussion of the sources of error in the observations, reference should be made to a class of phenomena present in the sun which under certain conditions may very seriously affect the results obtained for the rotation. These are the disturbances in the solar atmosphere which have been discussed recently under the term " Solar Vortices " (u), although their character is as yet by no means clear. The influence of the presence of such disturbances will be referred to more fully in connection with the considera- tion of the series of observations of 1908, and some numerical results will be given at that time. It is sufficient to call attention here to the fact that these solar storms sometimes affect very large regions of the sun's surface, and that throughout these regions the velocities due to the rotation of the sun may be greatly modified by the proper motions of the areas involved. 5. RESULTS FOR THE INDIVIDUAL PLATES, 1906-1907. The detailed results for the separate plates used in this investigation are given in Table 4. The main consideration borne in mind in the construction of this table has been to give all the data essential to an independent computation of the values derived from the plates. With this in view, at the beginning of the summary for each plate are given the constants used in the reduction of that plate, together with the necessary data for the computation of the latitudes and the auxiliary angles employed in correcting the observed values. Although most of the symbols have already been defined, for the sake of convenience it may be well to repeat them at this point. O = longitude of sun. fl = longitude ascending node of sun's equator = 74?4 for 1906. P - angle between sun's pole and north point. D = earth's heliographic latitude. "f = heliographic polar distance of point observed = 90 . n = angle made by the plane passing through the point observed, the sun's pole, and its center, with the plane corresponding to the sun's visible edge. l6 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. The diameter of the image is found by computation in the way already described from the almanac value of the sun's angular semi-diameter combined with the concave mirror setting of the Snow telescope. The "factor" referred to is the semi-diameter divided by one-half the distance between the diagonal prism openings which admit the light to the slit. The results for the individual lines of each plate for the various latitudes are given immediately below the constants for the plate. The values of A are the mean total displacements expressed in half-milli- meters. Hence the largest displacements measured are about 0.075 mm - I n the case of plates measured with the Gaertner comparator the values of the displacements have been multiplied by two, in order to make all of the quantities given homogeneous. The meaning of the other symbols employed in the tables is as follows : v = linear velocity corresponding to the sun's synodic period of rotation. ill correction for reduction to sidereal period of rotation. = daily angular velocity corresponding to the sidereal period of rotation. It is evident from the consideration of the methods of reduction that [ Value one-half revolution 1 v = A x \ . } x Factor x sec rj [ of micrometer in km j The values of the second quantity are obtained from the last column of Table 3. The corrections v\ are from the tables of Duner (s). The value of is readily found from v + v l by means of the formula , v + v l = [0.851228] - J COS$ where N is the number of seconds in a mean solar day and R is the sun's radius in kilometers. Some of the values for the individual plates given in Table 4 differ to a certain extent from those which appeared in an earlier communication (10). This is due mainly to the inclusion of a number of measures of plates by myself which I have found an opportunity to make in the interval since the first publication. As a consequence the mean values obtained represent much more nearly the average values for the two observers, Miss Lasby and myself, than did the earlier results. The values given here should accordingly be more nearly free from systematic peculiarities of measurement. There are also a few changes due to revision of the constants applied for correction of the observed velocities, particularly of the constant of reduction to the sidereal period of rotation. The final effect of all such changes on the mean values, how- ever, is very small, the largest difference in the mean for any normal place amounting to about 0.005 km. In the table the abbreviations L. and A. refer to Miss Lasby and myself, while the two comparators used, the Toepfer and Gaertner instruments, are designated by T. and G. respectively. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907. Plate TABLE 4. RESULTS FOE INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907. 3. 1906, May 3, 7 h 30 G. M. T. Measured by L. on T. Distance from Limb 2.4 mm. Quality, good. p-P 7T 17 seci; g g e O 42.4 5-2 6.4 83.6 36.9 1.250 o-n - - 32-0 . 20.2 20.5 69-5 II.O 1.019 p 23-9 35-2 35-4 54-6 6.6 1.007 D - - 3-8 50.2 50-3 39-7 5-o 1.004 Diameter 172.0 mm 65.2 65-3 24-7 4.2 1.003 Factor 1.028 80.2 80.2 9.8 3-9 i. 002 0=9?8 = 24?7 = 39?7 X A V JI + PJ E A V t + v l f A V +!>! km km km km . km km e 4196.699 0.145 1.891 2.027 14.61 0.127 1-658 1.787 13.96 0.098 1.282 1-395 12.87 4I97-2S7 0-145 1.891 2.027 14.61 0.128 1.670 1.799 14.06 O.IOO 1-305 1.418 13.08 4203.730 0.146 1.896 2.032 14.64 0.130 1.692 1.821 14-23 0.100 1-303 1.416 13.06 4209.144 0.146 1.890 2.026 14.60 0.132 1.714 -843 14.40 O.IO2 1.327 1.440 13.29 4216.136 0.146 1.887 2.023 14.58 0.129 1.672 .801 14.07 O.IOO 1.297 1.410 13.01 4220.509 0-145 1.875 2. Oil 14.49 0.131 1.694 .824 14-35 O.IO2 1-315 1.428 13.18 4232.887 0.147 1.892 2.028 14.62 0.132 1.699 .828 14.28 O.IOI .302 1-415 13.06 42S7-8IS 0.149 1.900 2.036 14.67 0-133 1.696 .825 14.26 O.IO4 331 1.444 13-32 4258.477 0.149 1.896 2.032 14.64 0.132 1. 680 .809 14.14 0.103 .312 1-425 13-15 4265.418 0.147 1.865 2.001 14.42 0.132 1.674 -803 14.09 0.104 .321 1-434 13-23 4266.081 0.149 1.886 2.O22 14-57 0-133 1.685 .814 14.18 O.IO3 305 1.418 13.08 4268.915 0.148 1.874 2.OIO 14.48 0.132 .672 .801 14.07 O.IO2 295 1.408 12.99 4276.836 0.146 1.848 1.984 14-3 0.131 659 .788 13-97 0.103 305 1.418 13.08 4284.838 0.147 1-855 .991 14-35 0.132 .670 799 14.06 O.IO2 .293 1.406 12.97 4287.566 0.147 1-855 .991 14-35 0.132 .668 797 14.04 0.103 305 1.418 13.08 4288.310 0.148 1.865 .001 14.42 0.132 .666 795 14-03 0.104 315 1.428 13.18 4290.377 0.147 1-852 .988 14-33 0.130 .641 770 13-83 O.IO4 313 1.426 13.16 4290.542 0.148 1.863 999 14.41 0.134 .686 .815 14.18 O.IO2 .288 1.401 12.93 4291.630 0.148 1.862 .998 14.40 0.132 .662 .791 14.00 0.104 .312 I-425 13-15 4294.936 0.148 i. 86 1 997 14-39 0-133 .673 .802 14.08 O.IO4 3" 1.424 13-14 = S46 = 6g!s - 8 3 !6 4196.699 0.068 0.892 0.981 12.02 0.038 0.504 0.564 n-43 0.008 0.132 0.160 10.19 4I97-2S7 0.069 0.904 0-993 12.17 0.037 0-493 0-553 II. 21 0.009 0.146 0.174 11.08 4203.730 0.070 0.916 1.005 12.32 0.041 0-543 0-603 12.22 0.009 0.145 0.173 1 1. 02 4209.144 0.070 0.914 1.003 12.29 0.041 0-541 0.601 12.18 0.008 0.131 0-159 10.13 4216.136 0.069 0.901 0.990 12.13 0.040 0.527 0.587 II.9O 0.009 0.145 0.173 11.02 4220.509 0.070 0.909 0.998 12.23 0.041 0.542 0.602 12. 2O 0.010 0.161 0.189 12.04 4232.887 0.070 0.90 1 0.990 12.13 0.041 0-539 0-599 12.14 O.OIO 0.161 0.189 12.04 4257-8I5 0.071 0.909 0.998 12.23 0-043 0-557 0.617 12.51 O.OI2 0.189 0.217 13.82 4258.477 0.072 0.919 .008 12-35 0.042 0-544 0.604 12.24 O.OIO 0.159 0.187 11.91 4265.418 0.073 0-933 .022 12.53 0.042 0-544 0.604 12.24 O.OII 0.175 0.203 12.93 4266.081 0.073 0.932 .O2I 12.51 0.043 0-553 0.613 12.43 O.OI2 0.189 0.217 13-82 4268.915 0.073 0.929 .Ol8 12.48 0.043 0-553 0-613 12-43 O.OII 0.174 0.202 12.87 4276.836 0.072 0.915 .004 12.30 0.042 0-541 0.601 12.18 O.OIO 0.159 0.187 11.91 4284.838 0.072 0.915 .004 12.30 0.042 0-543 0.603 12.22 O.OII 0.176 O.2O4 12.99 4287.566 0.072 0.913 .002 12.28 0.042 0.542 0.602 12.20 0.012 0.190 0.218 13.88 4288.310 0.074 0.938 .027 12.59 0.042 0-541 0.601 12.18 O.OIO 0.158 o.i 86 11.85 4290.377 0.073 0.925 .OI4 12.43 0.042 0-541 0.601 12. l8 O.OII 0.174 O.2O2 12.87 4290.542 0.072 0.911 .000 12.26 0.042 0.540 0.600 12. l6 O.OII 0.174 0.202 12.87 4291.630 0.072 0.911 .000 12.26 0.041 0.526 0.586 11.88 O.OII 0.173 O.2OI 12.80 4294.936 0.073 0.922 .on 12.39 0.043 0.550 0.610 12.37 O.OIO 0.158 o.i 86 11.85 1 8 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OP 1906-1907 Continued. Plate w 6. 1906, May 8, 6" o m G. M. T. Measured by L. on T. Distance from Limb 2.4 mm. Quality, good. P-P IT 1 seci 47.2 o 4-3 5-4 84.6 378 1.266 O-Q 27.2 19-3 19.6 70.4 9-9 1.015 P 22.9 34-3 34-4 55-6 5-9 1.005 D -3-3 49-3 49-4 40.6 4-4 1.003 Diameter 172.1 mm 64-3 64-3 25-7 3-7 1.002 Factor 1.028 79-3 79-3 10.7 3-4 1.002 ,- io!7 *- 25!7 ,- 40 6 A V P + ,, A ' . + * A tl T) ~\~ V, km km . km km km km , 4196.699 4I97.257 0.146 1.902 2.038 14-73 0.128 1.670 .798 14.17 0.097 1.266 -378 12.88 4203.730 0.146 1.894 2.030 14.67 0.130 1.682 .810 14.26 0.099 1.288 .400 13.09 4209.144 0.147 1.904 2.040 14.74 0.130 1.680 .808 14.25 0.098 1.273 -385 12.95 4216.136 0.146 1.889 2.025 14-63 0.127 1.644 .772 13.96 0.097 1.264 376 12.87 4220.509 0.148 1.908 2.044 14-77 0.130 1.677 .805 14.22 0.098 1.270 -382 12.92 4232.887 0.148 I-903 2.039 14-73 0.130 1.674 .802 14.20 O.IOI 1.301 413 13.21 4257.8I5 0.151 1.920 2.056 14.85 0.132 1.680 .808 14.25 O.IO2 1.301 413 13.21 4258.477 0.150 1.906 2.042 14-75 0.130 1.658 .786 14.07 O.IOI 1.283 395 13-04 4265.418 0.149 1.892 2.028 14.65 0.130 I.65S .783 14.05 O.IO2 1-295 .407 13.16 4266.081 0.151 1.912 2.048 14.80 0.131 1.664 1.792 14.12 O.IO2 1.294 .406 13.15 4268.915 0.151 1.910 2.046 14.78 0.130 1.652 1.780 14.02 0.102 1.292 .404 I 3- I 3 4276.836 0.151 1.908 2.044 14-77 0-132 1.671 1.799 14.17 O.IOI 1.279 391 13.01 4284.838 0.150 1.896 2.032 14.68 0.131 1.658 1.786 14.07 O.IO2 1.291 403 13.12 4287.566 0.150 1.893 2.029 14.66 0.132 1.665 1-793 14-13 O.IOI 1.278 390 13.00 4288.310 0.151 1.903 2-039 14-73 0.131 1.654 1.782 14.04 O.IO2 1.289 .401 13.10 4290.377 0.150 1.890 2.026 14.64 0.133 I.675 1.803 14.20 O.IOI 1.276 .388 12.98 4290.542 0.150 1.887 2.023 14.62 0.131 1.650 1.778 14.01 O.IO2 1.287 399 13.08 4291.630 0.150 1.886 2.022 14.61 0.132 1.662 1.790 14.10 O.IO2 1.285 397 13.06 4294.936 0.150 1.886 2.O22 14.61 0.132 1.662 1.790 14.10 0.102 1.284 396 13-05 *- 5S!6 *- ?o!4 ,- 84 : 6 4196.699 O.OO9 0.153 0.180 13.58 4I97.257 0.068 0.890 0.978 12.29 0.039 0.516 0-574 12.15 0.008 0.138 0.165 12-45 4203.730 0.068 0.887 0-975 12.25 0.039 0.5H 0.572 12. IO O.OIO 0.158 0.185 13.96 4209.144 0.067 0.873 0.961 12.08 0.040 0.527 0.585 12.38 0.009 0.154 0.181 13-65 4216.136 0.068 0.883 0.971 12. 2O 0.038 0.500 0.558 ii. 81 0.008 0.132 0.159 u-99 4220.509 0.070 0.905 0-993 12.48 0.040 0.524 0.582 12.32 O.OII 0.178 0.205 15-46 4232.887 0.069 0.890 0.978 12.29 0.040 0.523 0.581 12.30 0.009 0.151 0.178 13-43 4257.815 0.072 0.919 1.007 I2.6S 0.042 0.541 0-599 12.68 O.OIO 0.155 0.182 13-73 4258.477 0.070 0.896 0.984 12-37 0.042 0.540 0.598 12.66 O.OIO 0.161 o.i 88 14.18 4265.418 0.071 0.904 0.992 12.46 0.041 0.528 0.586 12.40 0.009 0.148 O.I7S 13.20 4266.081 0.072 0.916 1.004 12.62 0.042 0-539 0-597 12.63 O.OII 0.171 0.198 14.94 4268.915 0.072 0-915 1.003 1 2. 60 0.042 0-539 0-597 12.63 0.008 0.134 0.161 12.14 4276.836 0.072 0.914 i. 002 J2-59 0.041 0.528 0.586 12.40 0.009 0.148 o.i7S 13.20 4284.838 0.071 0.900 0.988 12.42 0.041 0.526 0.584 12.36 O.OIO o. 166 o.i93 14.56 4287.566 0.072 0.912 I.OOO 12.57 0.042 0-538 0.596 12.61 0.009 0.147 0.174 13-13 4288.310 0.071 0.898 0.986 12.39 0.041 0.526 0.584 12.36 O.OIO 0.153 0.180 13.58 4290.377 0.072 0.910 0.998 12.54 0.041 0-525 0.583 12.34 0.009 0.139 o.i 66 12.52 4290.542 0.072 0.909 0.997 12.53 0.044 0-560 0.618 13.08 0.009 o.i45 0.172 12.98 4291.630 0.072 0.909 0.997 12.53 0.043 0.548 0.606 12.83 0.008 . 0.128 0.155 11.69 4294.936 0.072 0.909 0-997 12.53 0.043 0-547 0.605 1 2.80 O.OIO 0.150 0.177 13-35 . RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907. TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907 Continued. Plate w 8. 1906, May 19, io h 3o m G. M. T. Measured by A. on G. Distance from Limb 2.3 mm. Quality, good. p-p f sec 7 O 0-0 p D 58.0 16.4 19-0 2.O Diameter 179.2 mm Factor 1.028 14.6 14.7 75-3 8.1 I.OIO 30.9 31.0 59-o 4.0 I.OO2 44-6 44-6 45-4 2.9 I.OOI 59-6 59-6 30.4 2.4 I.OOI 74-6 74.6 iS-4 2.1 I.OOI 90.9 89.1 o-9 2.0 I.OOI 0= o:. = ,5% = 30!4 A V .+., 1 A V . + ., 1 A 1 , + > 1 4196.699 0.144 km 1.877 km 2.016 O I4.3I 0.136 km 1.767 km 1.901 O 14.01 0.116 km I.5I8 km 1.642 O I3-52 4I97-257 0.150 I-95I 2.090 14.84 0.142 1.858 1.992 14.68 0.116 I.S2I 1.645 13-54 4203.730 4209.144 0.154 2.010 2.149 15.26 0.138 1.779 I.9I3 14.10 0.116 I-5I7 1.641 I3-5I 4216.136 0.144 1.865 2.004 14-23 0.136 1-773 1.907 14.06 O.I 2O 1.561 1.685 13-87 4220.509 0.150 1.944 2.083 14.79 0.140 1-852 1.986 14.64 0.122 1-574 1.698 13.98 4232.887 0.152 1.963 2.102 14.92 0.146 1.920 2.054 15-14 0.126 J-545 1.669 13-74 4257-8I5 0.148 1.897 2.036 14.46 0.144 1.906 2.040 15.04 0.124 1.714 14.11 4258.477 0.146 I.87I 2.010 14.27 0.142 1.866 2.OOO 14.74 0.128 1.639 1.763 I4-5I 4265.418 0.152 1-952 2.091 14-85 0.146 1.908 2.042 15.05 0.120 1.540 1.664 13.70 4266.081 0.152 1-945 2.084 14.80 0.140 1.829 1.963 14.47 0.126 1.601 I-725 14.20 4268.915 0.150 1-930 2.069 14.69 0.136 1.790 1.924 14.18 0.116 1.568 1.692 13-93 4276.836 0.152 1.936 2.075 14-73 0.138 1.818 1-952 14.38 0.118 1-583 1.717 4284.838 0.156 1.964 2.103 14-93 0.140 1.832 1.966 14.49 O.I 2O 1.601 1.725 14.20 4287.566 0.152 1.918 2-057 14.61 0.144 1.883 2.OI7 14.87 O.I 2O 1.607 I-73I I4-2S 4288.310 0.154 1-950 2.089 14.83 0.136 1.768 1.902 14.02 0.122 1-540 1.664 I3-70 4290-377 0.148 1.872 2. Oil 14.28 0.150 1.881 2.OI5 14-85 0.128 1.613 1-737 I4-30 4290.542 0.154 1.948 2.087 14.82 0.148 1.850 1.984 14.62 0.130 1.627 i-75i 14.41 4291.630 0.152 1.940 2.079 14.76 0.148 1.850 1.984 14.62 0.130 1.623 1-747 14.38 4294.936 0.146 1.835 1-974 14.02 0.142 1.770 1.904 14-03 0.128 1.598 1.722 14.17 = 4S!4 = S9. = 75:3 4196.699 O.IOO 1.214 1.320 13-35 0.064 0.825 0.908 12.52 O.O26 0-334 0-383 10.72 4I97-257 0.092 1.189 1.295 I3-09 0.066 0.871 0-954 13-15 O.O26 0.330 0-379 10.60 4203.730 4209.144 0.096 1-243 1-349 13-64 0.066 0.862 0-945 13.03 0.032 0.392 0.441 12.34 4216.136 0.094 1. 212 1.318 13-33 0.068 0.890 0-973 13-41 O.O28 0.358 0.407 "39 4220.509 0.094 1. 221 I-327 I3-42 0.066 0.874 0-957 13-19 0.030 0.391 0.440 12.31 4232.887 0.092 1.186 1.292 13.06 0.064 0.846 0.929 12.80 0.030 0-393 0.442 12.37 4257-8I5 O.IOO 1.279 1-385 14.00 0.072 0.910 0-993 13.69 0.034 0.438 0.487 13-63 4258.477 0.094 1. 211 I-3I7 I3-32 0.068 0.873 0.956 13.18 0.032 0.421 0.470 I3-I5 4265.418 0.098 1.247 1-353 13.68 0.066 0.836 0.919 12.67 0.030 0.383 0-432 12.09 4266.081 0.092 I-I75 1.281 12.95 0.064 0.811 0.894 12.32 0.032 0.401 0.450 12.59 4268.915 0.098 239 1-345 13.60 0.070 0.900 0.983 13-55 0.032 0.415 0.464 12.98 4276.836 0.096 .230 1.336 I3-SI 0.068 0.870 0-953 13-14 0.030 0-389 0.438 12.25 4284.838 0.094 .197 1-303 I3-I7 0.070 0.86 1 0-944 13.01 0.036 0.465 0.514 14-38 4287.566 0.096 .2IO 1.316 I3-30 0-074 0.890 0-973 13-41 0.034 0.446 0-495 13-85 4288.310 0.098 .231 1-337 I3-52 0.068 0-933 1.016 14.00 0.032 0.432 0.481 13-46 4290.377 0.096 .219 I-325 13-39 0.070 0.845 0.928 12.79 0.034 0.446 0-495 13-85 4290.542 0.092 .169 1-275 12.89 0.072 0.874 0-957 13-19 O.O26 0.330 0-379 10.60 4291.630 0.096 .216 1.322 I3-36 0.072 0.899 0.982 13-54 0.034 0.432 0.481 13-46 4294.936 0.096 .219 I-325 13-39 0.072 0.902 0.985 13-58 0.032 0-399 0.448 12.53 20 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907 Continued. Plate ia 19. 1906, June 12, 6 h 45 m G. M. T. Measured by L. on T. Distance from Limb 2.2 mm. Quality, good. Q 80.8 14.9 14.9 75- 3-i i. 002 O-n 60.4 29.9 29.9 60. 1.6 I.OOO P II. 2 44-9 44-9 45- i.i 1. 000 D 0.9 59-9 59-9 30- 0.9 I.OOO Diameter 169.1 mm 74-9 74-9 IS- 0.8 I.OOO Factor 1.027 89.9 89.9 o. [ 0.8 I.OOO = !i = isti = 3o!i A V + ! 1 A V + ! A t> + t>, s km km km km km km 4196.699 0.150 1-945 2.078 14-75 0.139 1.809 1.941 14.27 0.118 1-533 1.656 13-59 4197.257 0.152 1.970 2.103 14-93 0.140 1.820 1.952 14-35 0.118 1-533 1.656 13-59 4203.730 0.149 1.932 2.065 14.66 0.140 1.817 1.949 14-32 O.I22 1-583 1.706 14.00 4209.144 0.148 1.919 2.052 14-57 0.144 1.864 1.996 14.68 O.I2I 1-567 1.690 13-87 4216.136 0.150 1-937 2.070 14.70 0.137 1.770 1.902 13-99 0.116 1.498 1.621 13-30 4220.509 0.147 1.896 2.029 14.40 o.i44 1.817 1.949 14.32 O.Iig 1-532 I.655 13-58 4232.887 0.156 1.890 2.023 I4-36 0.144 1.847 1.979 14-55 O.I22 1-565 1.688 13-85 4257.815 0.150 1.904 2.037 14.46 0.140 1-773 1.905 14.01 0.124 1-574 1.697 13-93 4258.477 0.151 1.914 2.047 14-53 0.146 1.848 1.980 14.56 0.123 1-563 1.686 13.84 4265.418 0.152 1.926 2.059 14.62 0.146 1.848 1.980 14-56 O.I24 1-57' 1.694 13.90 4266.081 0.150 1.901 2.044 I4-5I 0.143 1.809 1.941 14.27 O.I2I 1-530 1-653 13-56 4268.915 0.151 1.910 2.043 14.50 0.140 1.769 1.901 13.98 O.I24 1-570 1.693 13.89 4276.836 0.152 1.914 2.047 14-53 0.145 1.822 1-954 14-37 O.I26 1.588 1.711 14.04 4284.838 0.152 1.910 2.043 14.50 0-145 1.822 1-954 14.37 0.122 1-534 1-657 13.60 4287.566 0.154 1-937 2.070 14.70 0.142 1.782 1.914 14.07 0.124 I.556 1.679 13-78 4288.310 0-153 1.919 0.052 14-57 0.142 1.782 1.914 14.07 O.I24 1-556 1.679 13-78 4290.377 0.154 1.932 2.065 14.66 0.141 1.771 I-903 14.00 O.I22 1-529 1.652 13-56 4290.542 0.150 1.881 2.014 I4-30 0.146 1.830 1.962 14.42 0.125 1.569 1.692 13.88 4291.630 0.152 1-905 2.038 14.47 0.146 1.830 1.962 14.42 O.I26 1-574 1.697 13-93 4294.936 0.156 1-954 2.089 14.82 0.144 1.804 1.936 14-23 O.I2I i-Si3 1.636 13-42 = 4S:i = &>:i * = 75?i 4196.699 0.088 I-I45 1.250 12-57 0.058 0-755 0-835 11.89 0.028 0.364 0.414 u-43 4197-257 0.088 1. 145 1.250 12.57 0.059 0.768 0.848 1 2.08 0.028 0.364 0.414 n-43 4203.730 0.091 1.181 1.286 12-93 0.059 0.766 0.846 12.05 0.031 0.403 0-453 12.51 4209.144 0.092 1.191 1.296 13-03 0.06 1 0.790 0.870 12.38 0.031 0.402 0.452 12.48 4216.136 0.090 1.162 1.267 12.74 0.058 0.751 0.831 11.84 0.030 0.387 0-437 12.07 4220.509 0.092 1.186 1.291 12.98 0.062 0-799 0.879 12.52 0.032 0.413 0-463 12.78 4232.887 0.090 I-I55 1.260 12.67 0.063 0.809 0.889 12.66 0.033 0.423 0-473 13.06 4257-815 0.095 1.209 I-3H 13.21 0.064 0.814 0.894 12.73 0.034 0.433 0.483 13-34 4258.477 0.094 1.191 1.296 13-03 0.062 0.788 0.868 12.36 0.033 0.419 0.469 12.95 4265.418 0.092 1.166 1.271 12.78 0.063 0.798 0.878 12.50 0.032 0.406 0.456 12.59 4266.081 0.094 1.190 1-295 13.02 0.065 0.824 0.904 12.87 0.034 0.431 0.481 13.28 4268.915 0.093 I-I73 1.278 12.85 0.062 0-783 0.863 12.29 0.033 0.418 0.468 12.92 4276.836 0.091 1.149 1-254 12. 6l 0.062 0.783 0.863 12.29 0.034 0.430 0.480 13-25 4284.838 0.094 1.183 1.288 12.95 0.065 0.817 0.897 12.78 0.033 0.416 0.466 12.87 4287.566 0.094 1.182 1.287 12.94 0.065 0.805 0.885 12.60 0.033 0.415 0.465 12.84 4288.310 0.093 1.169 1.274 12.81 0.064 0.805 0.885 12.60 0-033 0.415 0.465 12.84 4290.377 0.094 1.181 1.286 12.93 0.062 0-779 0.859 12.23 0-033 0.414 0.464 12.81 4290.542 0.094 1.180 1.285 12.92 0.064 0.804 0.884 12-59 0.034 0.427 0.477 I3-I7 4291.630 0.094 1.179 1.284 12.91 0.064 0.804 0.884 12-59 0.034 0.426 0.476 13-14 4294.936 0.094 1.179 1.284 12.91 0.066 0.827 0.907 12.92 0.032 0.401 0.451 12.45 RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907. 21 Plate TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907 Continued. 20. 1906, June 12, 7 h i5 m G. M. T. Measured by L. on T. Distance from Limb 2.2 mm. Quality, good. p P T i) seci O 80.9 o-n 6.5 29-9 29.9 p ii. i 44-9 44-9 D 0.9 59-9 59-9 Diameter 169.1 mm 74-9 74-9 Factor 1.027 89-9 89.9 60. 1 30.1 O.I 1.6 i.i 0.9 0.8 0.8 I.OOO I.OOO I.OOO I.OOO I.OOO = o:< = is!i = 3o!i A o M-., A V v + v 1 f A +! { km km . km km km km O 4196.699 0.146 .901 2.034 14-44 0-137 1-779 1.911 14.05 0.116 1.508 1.631 I3-38 4197-257 0.147 .911 2-044 I4-5I 0-139 1.800 1-932 14.21 0.119 1-544 1.667 13-68 4203.730 0.152 .971 2.104 14.94 0.141 1.822 1-954 14-37 O.I2I 1.566 1.689 13.86 4209.144 0.151 950 2.083 14-79 0.140 i. 806 1.938 14-25 O.I22 1-575 1.698 13-93 4216.136 0.148 .910 2.043 14.50 0.138 1.782 1.914 14.07 O.IlS I-523 1.646 I3-5I 4220.509 0.150 935 2.068 14-68 0.142 1.826 1.958 14.40 O.IlS 1.521 1.644 13-49 4232.887 0.154 975 2.108 U-97 0.142 1.820 1-952 14-35 0.122 1-563 1.686 13-84 4257-815 0.156 .982 2.II5 I5.O2 0.144 1.828 1.960 14.41 O.I24 1-575 1.698 13-93 4258.477 0.152 929 2.062 14.64 0.143 1.813 1-945 14.30 O.I22 1-550 1-673 13-73 4265.418 0-153 939 2.072 14.71 0.140 1.772 1.904 14.00 O.I2I 1-530 I-653 I3-56 4266.081 0-153 939 2.072 14.71 0.144 1.817 1-949 14.32 0.123 1.551 1.674 13-74 4268.915 0.152 924 2.057 14.60 0.143 1.805 1-937 14.24 O.I22 J-539 1.662 13.64 4276.836 0-154 945 2.078 14-75 0.143 1.803 1-935 14.23 0.122 1-537 i. 660 13.62 4284.838 0.150 .890 2.023 14.36 0.142 1.786 1.918 14.10 O.I24 1-559 1.682 13.80 4287.566 0.152 .910 2.043 14-50 0.142 1.781 I-9I3 14.07 O.I22 1-530 1-653 I3-56 4288.310 0.154 931 2.064 14.65 0.144 1.805 1-937 14.24 O.I2I I-5I9 1.642 13-47 4290-377 0.152 .909 2.042 14-49 0.142 1.780 1.912 14.06 O.I 2O 1-508 1.631 13-38 4290.542 0-153 .920 2-053 I4-58 0-143 1.794 1.926 14.16 O.I 2O 1-504 1.627 13-35 4291.630 0.152 .909 2.042 14.49 0.142 1.780 1.912 14.06 0.122 1-528 1.651 13-55 4294.936 0.156 1-954 2.087 14.82 0.140 1-753 1.885 13.86 O.I 21 I-5I7 1.640 13.46 = 4* = * 4196.699 0.086 1.116 1. 221 12.28 0.056 0.730 0.810 11-54 4197-257 0.088 1.141 1.246 12-53 0.058 0.752 0.832 11.85 4203.730 0.090 1.165 1.270 12.77 0.059 0.765 0.845 12.03 4209.144 0.091 .178 1.283 12.90 0.060 0-775 0-855 12.18 4216.136 0.088 -136 I.24I 12.48 0.058 0.749 0.829 11.81 4220.509 0.089 -145 1.250 12-57 0.062 0.799 0.879 12.52 4232-887 0.092 .179 1.284 12.91 0.062 0.797 0.877 12.49 4257-815 0.096 .217 1-322 13.29 0.066 0-839 0.919 13.09 4258.477 0.094 193 1.298 13-05 0.064 0.813 0.893 12.72 4265.418 0.091 151 1.256 12.63 0.063 0.801 0.881 12-55 4266.081 0.096 215 1.320 13-27 0.065 0.823 0-903 12.86 4268.915 0-093 175 1.280 12.87 0.063 0-797 0.877 12.49 4276.836 0-093 173 1.278 12.85 0.062 0.785 0.865 12.32 4284.838 0.092 159 .262 12.69 0.06 1 0.770 0.850 1 2. 1 1 4287.566 0.090 .132 237 12.42 0.064 0.804 0.884 12-59 4288.310 0.094 .181 .286 12-93 0.062 0-779 0.859 12.23 4290.377 0.091 .141 .246 12-53 0.063 0.790 0.870 12.39 4290.542 0.091 .141 .246 "S3 0.062 0-775 0-855 12.18 4291.630 0.091 .141 .246 12-53 0.064 0-799 0.879 12.52 4294.936 0.094 .179 .284 12.91 0.063 0.789 0.869 12.38 22 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907 Continued. Plate w 21. 1906, June 12, 7" 45 G. M. T. Measured by L. on T. Distance from Limb 2.2 mm. Quality, good. P-P o-n p D 80.9 6-5 it. i 0.9 Diameter 169.1 mm Factor 1.027 14.9 14.9 75-i 3-2 .002 29.9 29.9 60. i 1.6 .OOO 44.9 44-9 45- 1 i.i .OOO 59.9 59-9 30.1 0.9 .000 73-9 73-9 16.1 0.8 .000 74-9 74-9 iS-i 0.8 .000 89.9 89.9 O.I 0.8 .000 #-* - rfi * - .a:, A V , + ,, 1 A V , + i A V V + II j i. 4196.699 0.146 km .897 km 2.030 14.41 0.138 km 1.794 km 1.926 D I4.I6 0.137 km .780 km 1.912 14-13 4197-257 0.148 923 2.056 14.60 0-139 1.801 1-933 14.21 0.138 .790 1.922 14.20 4203.730 0.149 934 2.067 14.67 0.141 1-823 1-955 14.38 0.140 .812 1.944 14-36 4209.144 0.152 963 2.096 14.88 0.142 .831 1.963 14.21 0.139 .796 1.928 14.24 4216.136 0.148 .910 2.043 14-50 0-139 793 1.925 I4.l6 0.138 779 I.9II 14.12 4220.509 0.150 934 2.067 14.67 0.140 .801 1-933 14.21 0.139 .791 1.923 14 21 4232.887 0.152 942 2.075 M-73 0.143 .822 1-954 14-37 0-143 833 1.965 I4.52 4257-SiS 0.154 -953 2.086 14.81 0.143 .825 1-957 14-39 0.145 .840 1.972 14-57 4258.47? 0.152 .928 2.061 14.63 0.142 .800 1.932 14.21 0.143 .815 1.947 14.38 4265.418 0.154 949 2.082 14.78 0.144 .822 1-954 14-37 0.144 .823 1-955 14.44 4266.081 0.152 924 2-057 14.60 0-143 .808 1.940 14.27 0.142 .805 1-937 I4-3I 4268.915 0.150 .898 2.031 14.42 0.143 803 1-935 I4.23 0.144 .822 1-954 14.44 4276.836 0-153 930 2.063 14.65 0.145 .824 1.956 14.38 0.142 794 1.926 14.23 4284.838 0-153 1.923 2.056 14.60 0.142 .786 1.918 I4.IO 0.144 815 1.947 14.38 4287.566 0.154 1.936 2.069 14.69 0.143 795 1.927 14.17 0.146 835 1.967 14-53 4288.310 0.154 1-935 2.068 14.68 0.143 -795 1.927 14.17 0.140 .760 1.892 13.98 4290.37? 0.150 1.885 2.018 14-33 0.145 1.819 I-95I 14-35 0.143 794 1.926 14.23 4290.542 0.152 1.907 2.040 14.48 0.142 1.780 1.912 I4.O6 0.142 .784 1.916 14.16 4291.630 0-153 1.920 2.053 14.58 0.144 1.804 1.936 14.24 0.144 .809 1.941 14-34 4294-936 0.154 1.929 2.062 14.64 0.141 1.768 1.900 13-97 0.145 .818 1.950 14.41 \ = 3!' . = 45!, 6oi * = K.< A A V . + ,, A s . + ,, A V M-i A , + ,, km km . km km km km km km 4196.699 0.116 I.5I5 1.63* 13-44 0.088 1.146 1.251 12.58 0.056 0.727 0.8o; 11.49 0.027 0-354 0.40.1 11.15 4197.257 0.120 1-555 1.67? 13-77 0.087 1.131 i.2 3 C 12.43 0.058 0.749 0.82C 11.81 0.029 0-375 0.42; "73 4203.730 O.I 2O 552 1.675 13-74 0.090 1.165 I.27C > 12.77 0.06 1 0.788 0.86* 12.36 0.030 0.389 0-43? 12.12 4209.144 O.I 2O 550 I-673 13-73 0.090 1.164 I.26{ 12.76 0.06 1 0.787 0.86; 12.35 0.030 0.389 o-43? 12.12 42I6.I36 0.118 523 1.641 13-51 0.090 1.162 1.26- 12.74 0.057 0-735 0.8 1 ; ii. 61 0.029 0-374 0.424 II-7I 4220.509 O.I 2O 546 1.66? 13-70 0.090 1.161 I.26( ' 12.73 0.060 0-774 0.854 12. 16 0.031 0.398 0.44? 12-37 4232.887 O.I2I 552 1.67; J3-75 0.095 1.213 I.3IJ ! 13.26 0.06 1 o.779 o.8 5 c 12.23 0.032 0.423 0-473 13.04 4257.815 0.124 -568 1.691 13.88 0.098 1.244 I-34C 1 13-57 0.064 0.810 o.Sgc i 12.68 0.034 0.438 0.48? 13-47 4258.477 O.I22 543 i.66f 13-67 0.093 1.189 1.29^ I 13-01 0.062 0.785 0.86 = 12.32 0.034 0.409 0-45? 12.67 4265.418 O.I22 54i 1.664 13-65 0.094 1.187 1.29: 12.99 0.062 0.784 0.86^ 12.30 0.032 0.404 0-454 12-54 4266.081 0.123 555 1.678 13-78 0.092 1.166 1.271 12.78 0.064 0.808 0.88? 12.65 0.031 0-434 0.484) 13.36 4268.915 0. 121 529 1.65: 13-56 0.092 1.165 I.27C > 12.77 0.060 0-759 o.8 3 c n-95 0.034 0-454 0.504 13.92 4276.836 O.I22 537 i.66c > 13.62 0.093 1.174 I.27C 1 12.86 0.064 0.806 o.88( 12.62 0.032 0.419 0.46$ 12-95 4284.838 O.I2I -524 1.64; 13-52 0.094 1.182 1.28- ' 12.94 0.062 0.784 0.864 12.30 0.032 0.403 0-453 12.51 4287.566 O.I22 53 1-65; 13-56 0.093 1.167 1.27: 12.79 0.064 0.801 0.881 12.55 0.034 0.428 0.478 13.20 4288.3IO 0.122 529 1.65: 13-56 0.092 1.157 1.26: 12.69 0.062 0-779 o.8 S c 12.23 0.034 0.428 0.478! 13.20 4290.377 0.126 578 1.701 13.96 0.093 1.167 1.27: 12.79 0.061 0.769 0.84? 12.09 0.032 0.402 0.452 12.48 4290.542 0.123 543 I.66C 13-67 0.091 1.146 1.251 12.58 0.064 0.800 o.88c > 12.53 0.031 0.388 0.438 12.09 4291.630 0.124 1-553 i.6jt 13-75 0.090 1.131 I.23< > 12.43 0.063 0.789 o.86c 12.38 0.034 0.428 0-47* 13.20 4294.936 O.I22 I-527 i.osc 13-54 0.092 I.26< > 12.67 0.062 0.779 0-85? 12.23 0.034 0.427 0.473 I3-I7 RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907. TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907 Continued. Plate ID 23. 1906, June 15, 6 h o m G. M. T. Measured by L. on T. Distance from Limb 2.3 mm. Quality, good. p P T 1 secTi Q 83-7 15.0 iS-o 75-0 4.5 I.OO3 0-0 9-3 31.0 31.0 59- 2-3 1. 001 P 9-9 4S-o 4S- 45- i-7 I.OOO D 1.2 60.0 60.0 30.0 1.4 I.OOO Diameter 169.3 mm 7S-o 7S- 15.0 1.2 I.OOO Factor 1.028 90.0 90.0 0.0 1.2 I.OOO <*> = oo = is!o = 3! A V v + v l 1 A +i A V + T, km km km km km km o 4196.699 0.146 1.900 2-033 14-43 0.138 1-797 .929 14.18 0.118 536 1.659 13.60 4197-257 0.148 1.925 2.058 14.61 0.138 1-797 929 14.18 0.119 547 1.670 13.69 4203.730 0.149 1.936 2.069 14.69 0.140 1.815 947 14-31 0.119 545 1.668 13-67 4209.144 0.150 1-913 2.046 14-53 0.141 1.824 956 14.38 O.I 21 567 1.690 13-85 4216.136 0.148 1.893 2.026 14-38 0138 1-785 .917 14.09 O.II8 .526 1.649 13-52 4220.509 0.150 1.903 2.036 14-45 0.140 .808 .940 14.26 O.IlS 524 1.647 13-50 4232.887 0.150 1-903 2.036 14-45 0.142 .825 957 14.38 O.I22 .566 1.689 13-85 4257-815 0.152 1.930 2.063 14-65 0.143 .817 949 14-33 0.122 547 1.670 13.69 4258.477 0.153 1.948 2.081 14-77 0.143 .817 949 14.33 O.I23 1-557 i. 680 13-77 4265.418 0.154 1.952 2.085 14.80 0.145 .832 .964 14.44 O.I22 1-544 1.667 13-67 4266.081 0.152 1.926 2.059 14.62 0.142 .800 932 14.20 0.123 1-554 1.677 13-75 4268.915 0.153 1-935 2.068 14.68 0.144 .820 952 14.35 O.I24 i-57i 1.694 13-88 4276.836 0.156 1.969 2.102 14.92 0.140 .768 1.900 13.96 O.I2I 1.526 1.649 13-52 4284.838 0-153 1.928 2.o6l 14.63 0.142 .786 1.918 14.10 0.123 1.548 1.671 13-70 4287.566 0.153 1.927 2.o6o 14.62 0.143 .798 1-930 14.18 O.I2I 1.522 1.645 13-49 4288.310 0.152 1.909 2.042 14.50 0.143 798 1.930 14.18 0.123 1.546 1.669 13.68 4290-377 0.152 1.909 2.042 14-50 0.142 -783 I-9IS 14.08 0.124 1.560 1.683 13.80 4290.542 0.151 1.898 2.031 14.42 0.142 -783 I-9I5 14.08 O.I22 '535 1.658 13-59 4291.630 0.152 1.907 2.040 14.48 0.144 .807 1-939 14-25 0.123 I-S4S 1.668 13-67 4294.936 0.152 1.907 2.O40 14.48 0.142 .781 1.912 14.05 O.I24 1-558 i. 68 1 13-78 = 45! = S9. = is'.o 4196.699 0.087 1.132 1-237 12.42 0.057 0-743 0.825 "37 O.O29 0.380 0.430 n.8o 4197-257 0.090 1.163 1.268 12.73 0.057 0-743 0.825 11-37 0.030 0.391 0.441 12 IO 4203.730 0.088 I-I45 1.250 12-55 0.059 0.766 0.848 11.69 O.028 0.365 0.415 11.38 4209.144 0.092 1.191 .296 13.01 0.060 0.776 0.858 11.83 0.030 0.389 0-439 I2.O4 4216.136 0.087 1. 122 .227 12.32 0.058 0.750 0.832 11.47 O.O29 0.378 0.428 11.74 4220.509 0.088 I-I37 .242 12-47 0.061 0.787 0.869 11.98 0.030 0.388 0.438 12.01 4232.887 0.090 I-IS4 259 12.64 0.062 0.799 0.881 12.14 0.031 0.398 0.448 12.29 4257-815 0.092 I.I7O 275 12.80 0.062 0.791 0.873 12.03 0.031 0.396 0.446 12.23 4258.477 0.094 I-I95 .300 I3-05 0.062 0.791 0.873 12.03 0.030 0-379 0.429 11.77 4265.418 0.092 1.165 1.270 12.75 0.063 0.800 0.882 12. 16 0.032 0.386 0.436 11.96 4266.081 0.090 I-I39 1.244 12.49 0.062 0.789 0.871 I2.OI 0.034 0.431 0.481 13-19 4268.915 0.091 I.I5I 1.256 12. 6l 0.058 0-734 0.8 1 6 11.25 0.032 0.405 0-455 12.48 4276.836 0.092 1.161 1.266 12.71 0.062 0.787 0.869 11.98 0.032 0.405 0-455 12.48 4284.838 0.094 1.184 1.289 12.94 0.063 0-793 0.875 I 2. 06 0.031 0-393 0-443 12.15 4287.566 0.092 1.158 1.263 12.68 0.06 1 0.766 0.848 11.69 0.031 0-393 0-443 12.15 4288.310 0.093 1.164 1.269 12-74 0.062 0.780 0.862 11.88 0.031 0-393 0-443 12.15 4200.377 0.089 1.116 1. 221 12.26 0.062 0-779 0.861 11.87 0.032 0.403 0-453 12.43 4290.542 0.090 1.131 1.236 12.41 0.060 0-755 0.837 "54 0.032 0.403 0-453 12-43 4291.630 0.094 1.182 1.287 12.91 0.061 0.765 0.847 11.68 0.032 0.403 0-453 12.43 4294.936 0.090 1.130 1.235 12.40 0.065 0.815 0.897 12.36 0.031 0.389 0-439 12.04 24 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907 Continued. Plate w 24. 1906, June 15, 6 h 15 G. M. T. Measured by L. on T. Distance from Limb 2.4 mm. Quality, good. P-P sec?) O o-n p D 83-7 9-3 9.9 1.2 Diameter 169.5 mm Factor 1.030 15.0 30.0 15.0 30.0 7S- 60.0 4-5 2.2 1.003 I.OOI 45- 60.0 45-o 60.0 4S-o 30.0 1.7 J-4 1. 000 1. 000 75-o 7S-o 15.0 1.2 I.OOO 90.0 90.0 o.o 1.2 I.OOO oo = is!o = 30o A V+ Dj e A 11 i> + fl, A V D + Dj km km km km , km km . 4196.699 0.148 1.923 2.056 14.60 0.138 795 1.927 14.16 0.118 1-540 1.663 13-63 4197.257 0.147 I.QI2 2-045 14-52 0.138 795 1.927 14.16 0.117 I.52S 1.648 I3-5I 4203.730 0.150 1.946 2.079 14.76 0.138 792 1.924 14.14 O.I2I 1-575 1.698 13.92 4209.144 0.150 1.944 2.077 14-75 0.140 -815 1.947 14-31 O.I 2O 1-558 I.68I I3-78 4216.136 0.146 I.SgO 2.023 14-36 0.138 .790 1.922 14-13 O.II8 1.528 1.651 13-53 4220.509 0.150 1.940 2.073 14.72 0.141 .821 1-953 14-35 O.I22 1.581 1.704 13-97 4232.887 0.152 1-955 2.088 14.82 0.142 .827 1-959 14.40 O.I22 I-57I 1.694 13.89 4257.815 0.153 i-95i 2.084 14.79 0.145 .848 1.980 M-55 0.122 i-553 1.676 13-74 4258.477 0.154 1.958 2.091 14-85 0.142 1.805 1-937 14.24 O.I2I 1-541 1.664 13.64 4265.418 0-155 1.969 2.IO2 14.92 0.142 1.802 1-934 14.21 0.123 1.562 1.685 13.81 4266.081 0.153 1-939 2.072 14.71 0.143 1.816 1.948 14.32 O.I2I 1-537 1. 660 13.61 4268.915 0.153 1-937 2.O7O 14.70 0.142 .801 1-933 14.21 0.122 1-548 1.671 13.70 4276.836 0.152 1.923 2.056 14.60 0.144 .822 1-954 14.36 0.123 1-555 1.678 13.76 4284.838 0.153 I-93I 2.064 14.65 0.142 .788 1.920 14.11 0.123 i-55i 1.674 13.72 4287.566 0.153 1.926 2.059 14.62 0.144 .814 1.946 14.30 O.I22 I-536 1.659 13.60 4288.310 0.155 i-95i 2.084 14.80 0.143 .800 1.932 14.20 0.124 1.560 1.683 13.80 4290.377 0.151 1.900 2-033 14.43 0.142 1-785 1.917 14.09 0.123 J-547 1.670 13.69 4290.542 0.152 1.911 2.044 M-S 1 0.143 1.799 I-93I 14.19 O.I22 1-535 1.658 13-59 4291.630 0.153 1.924 2.057 14.60 0.142 1.785 1.917 14.09 0.125 i-57i 1.694 13.89 4294.936 0.152 1.909 2.O42 14.50 0.144 i. 808 1.940 14.26 O.I24 J-555 1.678 I3-76 = 4Sto =6o?o = 75! 4196.699 0.089 1.162 1.267 12.72 0.060 0.779 0.86 1 12.23 O.O28 0.366 0.416 11.41 4197.257 0.088 1.147 1.252 12.57 0.058 0-754 0.836 11.87 O.O28 0.366 0.416 11.41 4203.730 0.090 1.172 1.277 12.82 0.060 0.778 0.860 12.21 0.030 0.390 0.440 12.07 4209.144 0.091 1.182 .287 12.92 0.059 0.763 0.845 12.00 0.031 0.400 0.450 12.34 4216.136 0.088 1.140 245 12.50 0.058 0-751 0-833 11.83 0.030 0.389 0-439 12.04 4220.509 0.090 1.164 .269 12.74 0.060 0-777 0.859 12. 2O 0.030 0.389 0-439 12.04 4232.887 0.091 1.172 277 12.82 0.062 0.800 0.882 12-52 0.032 0.412 0.462 12.67 4257.815 0.092 1.171 .276 12.81 0.066 0.841 0.923 13.11 0.034 0.431 0.481 13-19 4258.477 0.091 I-I59 .264 12.69 0.062 0.789 0.871 12-37 0.033 0.420 0.470 12.89 4265.418 0.093 1.181 .286 12.91 0.064 0.815 0.897 12.74 0-033 0.420 0.470 12.89 4266.081 0.094 1.194 -299 13-04 0.062 0.787 0.869 12.34 0-033 0.420 0.470 12.89 4268.915 0.092 1.167 .272 12-77 0.062 0.787 0.869 12-34 0.032 0-405 0-455 12.48 4276.836 0.092 1.164 .269 12.74 0.063 0.800 0.882 12.52 0.031 0-394 0.444 12. 18 4284.838 0.090 i-i3S .240 12.45 0.062 0.782 0.864 12-37 0.031 0-393 0-443 12.15 4287.566 0.093 1.170 -275 12.80 0.065 0.816 0.898 12.75 0-035 0.441 0.491 13-47 4288.310 0.092 1.158 .263 12.68 0.063 0.792 0.874 12.41 0.032 0.404 0-454 12.45 4290.377 0.094 1.182 .287 12.92 0.060 0.762 0.844 11.98 0.032 0.404 0.454 12.45 4290.542 0.093 1.170 275 12.80 0.062 0.781 0.863 12.25 0-033 0.414 0.464 12.73 4291.630 0.093 1.169 1.274 12.79 0.066 0.831 0.913 12.96 0.032 0.403 0-453 12.43 4294.936 0.094 1.179 1.284 12.89 0.064 0.806 0.888 12.61 0.032 0.403 0-453 12.43 RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907. TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907 Continued. Plate u 25. 1906, June 15, 6 h 35 G. M. T. Measured by L. on T. Distance from Limb 2.3 mm. Quality, good. P-f sec 7) O o-n p D 83-7 9-3 9.9 1.2 Diameter 169.5 mm Factor i .030 15.0 30.0 15.0 30.0 7S-o 60.0 4-5 2-3 1.003 I.OOI 45-o 60.0 45- 60.0 45-o 30.0 i-7 1.4 1. 000 I.OOO 75-Q 7S- 15.0 1.2 I.OOO 90.0 90.0 o.o 1.2 I.OOO #- oo = is! *- 3! A M-., 1 A V . + ., f A V ,-M, km km km km km km 4196.699 0.149 943 2.076 14-74 0.139 1.810 1.942 14.27 0.118 1-537 1.660 13.61 4197-257 0.150 957 2.090 14.84 0.142 1.847 1.979 14-55 O.I 2O 564 1.687 13-83 4203.730 0.151 965 2.098 14.89 0.144 1.869 2.OOI 14.71 0.118 -540 1.663 13-63 4209.144 o.i54 .989 2.122 15.06 0.144 1.867 1.999 14.69 0.127 .651 1-774 14-54 4216.136 0.146 .889 2.022 14.36 0.141 1.823 1-955 14-37 0.116 .502 -625 13-32 4220.509 0.150 937 2.070 14.70 0.146 1.887 2.019 14.84 0.125 .614 737 14.24 4232-887 0.151 943 2.076 14.74 0.144 1-853 1.985 14-59 0.120 -542 .665 13-65 4257-8I5 0.150 .911 2.044 14-51 0.145 1.843 1-975 14-52 0.124 -576 .699 13-93 4258-477 O.I5S .961 2.094 14-87 0.145 1-843 1-975 14-52 O.I 2O .526 649 13-52 4265.418 0.147 .867 2.OOO 14.20 0.146 1-854 1.986 14.60 0.125 .586 709 14.01 4266.081 0.151 .917 2.O50 H-55 0.148 1.878 2.010 14-77 O.I 20 -524 .647 13-50 4268.915 0.152 .927 2.060 14.62 0.146 1.851 1.983 14-58 O.I 21 530 653 13-55 4276-836 0.151 .909 2.O42 14.50 0.143 1. 808 1.940 14.26 O.I22 541 .664 13-64 4284.838 0.154 .941 2.074 14.72 0.144 1.818 1.950 14-33 0.122 -538 .661 13.62 4287.566 0.154 936 2.069 14.69 0.146 1.839 1.971 14.49 O.II9 499 .622 13-30 4288.310 0-153 925 2.058 14.61 0.142 1-777 1.909 14-03 O.II7 474 597 13.09 4290.377 0.152 .911 2.044 I4-5I 0.138 1.738 1.870 13-74 0.120 .508 .631 13-37 4290.542 0-153 .921 2.054 14.58 0.142 1.776 1.908 14.02 O.I22 533 .656 13-58 4291-630 0.150 .888 2.O2I 14-35 0.142 1.776 1.908 14.02 O.II9 497 .620 13.28 4294-936 0.152 909 2.O42 14.50 0-144 1.808 1.940 14.26 O.I2I 517 .640 13-44 *- 45> *- 6oo ,- 75? 4196.699 0.087 135 1.240 12.45 0.054 0.703 0.785 11.15 0.026 0.340 0.390 10.63 4197-257 0.088 147 1.252 12.57 0-059 0.769 0.851 1 2.08 0.035 0.442 0.492 13-41 4203.730 0.086 .120 1.225 12.30 0.063 0.819 0.901 12.79 0.032 0.416 0.466 12.70 4209.144 0.090 .169 1.274 12-79 0.066 0-855 0-937 13-30 0.031 0.405 0-455 12.40 4216.136 0.086 .114 1.219 12.24 0-053 0.685 0.767 10.89 0.025 0-324 0-374 10.19 4220.509 0.096 .242 1-347 I3-S2 0.058 0.748 0.830 11.79 0.031 0.342 0.392 10.68 4232.887 0.093 .197 1.302 13-07 0.062 0.798 0.880 12.50 0.032 0.411 0.461 12.56 4257-815 0.092 .171 1.276 12.81 0.062 0.790 0.872 12.38 0.034 0.447 0-497 13-54 4258.477 0.090 145 1.250 12-55 0.060 0.764 0.846 12.01 O.027 0-345 0-395 10.76 4265.418 0.086 .092 1.197 12. 02 0.064 0-759 0.841 11.94 0.031 0-394 0-444 12.10 4266.081 0.096 .220 1-325 I3-30 0.06 1 0.776 0.858 12.18 0.026 0-331 0.381 10.38 4268.915 o.ogi 155 1.260 12.65 0.065 0-776 0.858 12.18 0.032 0.406 0.456 12-43 4276.836 0.090 .138 1-243 12.48 0.063 0.800 0.882 12.52 0.032 0.406 0.456 12.43 4284.838 0.095 95 i. 200 12.05 0.068 0.857 0-939 13-33 0.028 0-354 0.404 II. OI 4287.566 0.092 .158 1.263 12.68 0.066 0-832 0.914 12.98 0.030 0.378 0.428 11.66 4288.310 0.091 H5 1.250 12-55 0.057 0.717 0-799 "35 O.O29 0.364 0.414 11.28 4290.377 0.096 .207 1.312 13-17 0.064 0.807 0.889 12.62 0.037 0.465 0.515 14.04 4290.542 0.092 157 1.262 12.67 0.062 0.782 0.864 12.27 O.O28 0-373 0.423 "53 4291.630 0.097 .219 1-324 13.29 0.059 0.742 0.824 11.70 O.O29 0.364 0.414 11.28 4294-936 0-097 .217 1.322 13.27 0.064 0.802 0.884 12.55 0.028 0-353 0.403 10.98 26 AN INVESTIGATION OF THE ROTATION PERIOD OP THE SUN BY SPECTROSCOPIC METHODS. TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907 Continued. Plate w 26. 1906, June 16, 6' 1 20' G. M. T. Measured by L. on T. Distance from Limb 2.7 mm. Quality, good. 84.5 iS-o 15-1 74-9 4.9 1.004 O-fi 10.1 30.0 30.0 60.0 2-5 I.OOI P 9-5 45-0 4S-o 45-0 1.8 I.OOI D 1.3 60.0 60.0 30.0 i-5 I.OOO Diameter 1 70.0 mm 7S-o 7S- 15.0 i-3 I.OOO Factor 1.033 90.0 90.0 o.o i-3 I.OOO ,- o?o #- is!o = 3! \ A A V , + ,, 1 A I , + ,, e A V 11 4- 11, 1 km km km km km km 4196.699 0.150 1.956 2.089 14.83 0.138 1.804 1.936 14.22 0.114 1.491 1.614 13.22 4197-257 0.148 1.936 2.069 14.69 0.138 1.803 1-935 14.22 0.115 1.501 1.624 I3-30 4203.730 0.148 I-93I 2.064 14.65 0.144 1.878 2.OIO 14-77 0.116 1.509 1.632 13-37 4209.144 0.152 1.972 2.105 14.94 0.144 1.876 2.008 14-75 O.I 2O 1-558 I.68I 13-77 4216.136 0.147 1.910 2.043 0-137 1-777 1.909 14.02 O.II2 1-455 1-578 12.92 4220.509 0.147 1.910 2.043 14.50 0.144 1.867 1-999 14.69 O.I22 1.581 1.704 13.96 4232.887 0.152 1-963 2.096 14.88 0.144 1.858 1.990 14.62 O.I2I 1.562 1.685 13.80 4257-815 0.159 2.030 2.163 15-36 0.144 1.848 1.980 14.55 O.llS 1.506 1.629 13-34 4258.477 0.155 1.978 2. Ill 14.99 0.147 1.876 2.008 14.75 O.I 2O I-527 1.650 I3-5I 4265.418 0.152 1.936 2.069 14.69 O.I4S 1.848 1.980 14.55 0.123 1-565 1.688 13.82 4266.081 0.152 1-935 2.068 14.68 0.146 1.858 1.990 14.62 O.llS I-503 1.626 I3-32 4268.915 0.152 934 2.067 14.67 0.150 1.907 2.039 14.98 0.116 1.476 1-599 13.10 4276.836 0.151 .912 2.045 14-52 0.144 1.823 1-955 14.36 O.I 2O 1.520 1.643 I3-46 4284.838 0.154 -945 2.078 14-75 0.148 1.867 1-999 14.69 0.116 1-475 1.598 13.09 4287.566 0.151 907 2.O4O 14-48 0.148 1.867 1-999 14.69 0.122 1-538 i. 66 1 13.60 4288.310 0.150 .904 2.037 14.46 0.149 1. 880 2.OI2 14.78 O.II7 1.481 1.604 I3-I4 4290.37? 0.155 964 2.097 14.89 0.142 1.790 1.922 14.12 O.llS 1.491 1.614 13.22 4290.542 0.154 942 2.075 14-73 0.144 1.815 1-947 14-30 O.I 2O 1.512 1-635 13-39 4291.630 0.148 .868 2.001 14.21 0.146 1.841 1-973 14.49 O.I2I 1.522 1.645 13-47 4294.936 0.157 1.976 2.109 14.97 0.144 1.811 1-943 14.27 O.I 2O 1.510 1-633 13-37 ,- 45? *- *, = 74:, 4196.699 0.087 1.136 1.241 12.45 0.060 0.787 0.867 12.27 0.033 0-434 0.484 I3-I9 4197-257 0.086 .126 1.231 12.35 0.058 0.761 0.841 11.91 0.030 0-393 0-443 12.07 4203.730 0.088 145 1.250 12.54 0.06 1 0.796 0.876 12.40 0.031 0.407 0-457 12.45 4209.144 0.093 .206 1.311 13-14 0.060 0.782 0.862 12. 2O 0.036 0.469 0-519 14.14 4216.136 0.088 .142 1.247 12.51 0.065 0.846 0.926 13.11 0.030 0.391 0.441 I2.O2 4220.509 0.093 203 1.308 13.12 0.06 1 0-793 0.873 12.36 0.030 0.390 0.440 "99 4232.887 0.090 .160 1.265 12.69 0.062 0.801 0.881 12.47 0.034 0.438 0.488 I3-30 4257-815 0.090 1.150 1-255 12.59 0.054 0.732 0.812 11.49 0.030 0-383 0-433 11.80 4258-477 0.092 1.174 1.279 12.83 0.065 0.830 0.913 12.92 0-035 0-445 0.495 13-49 4265.418 0.090 1.148 1-253 12-57 0.059 o-753 0-833 11.79 0.030 0.382 0-432 11.77 4266.081 0.095 1.209 1-314 13.18 0.063 0.803 0.883 12.50 0.032 0.409 0-459 12.51 4268.915 0.094 1.197 1.302 13.06 0.060 0.763 0.843 "93 0.035 0.444 0-494 13.46 4276.836 0.092 1.166 1.271 12.75 0.063 0.801 0.881 12.47 0.028 0.382 0.432 11.77 4284.838 0.092 1.163 1.268 12.72 0.057 0.716 0.796 11.27 0.034 0.431 0.481 13.11 4287.566 0.093 1-173 1.278 12.82 0.068 0.860 0.940 13-31 0.034 0.431 0.481 13.11 4288.310 0.095 1.199 1.304 13.08 0.06 1 0.770 0.850 12.03 0.030 0.380 0.430 11.72 4290.377 0.092 1.159 1.264 12.68 0.06 1 0.769 0.849 12. 02 0.032 0.406 0.456 12-43 4290.542 0.094 1.183 1.288 12.92 0-057 0.719 0-799 11.31 0.031 0-391 0.441 12. 02 4291.630 0.094 1.183 1.288 12.92 0.058 0-733 0.813 11.51 O.O28 0-355 0.405 II.O4 4294.936 0.096 1.207 1.312 13.16 0.064 0.804 0.884 12.51 0.030 0-379 0.429 11.69 RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907. TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907 -Continued. Plate 27. 1906, June 16, 7 h s ra G. M. T. Measured by L. on T. Distance from Limb 2.7 mm. Quality, good. t-P SCOT o 84.6 15.0 iS-i 74-9 4-9 1.004 o-n 10.2 30.0 30.0 60.0 2-5 I.OOI p 9-5 4S-o 45- 45- 1.8 I.OOI D i-3 60.0 60.0 30.0 i-5 I.OOO Diameter 170.0 mm 7S-o 75-o 15-0 i-3 I.OOO Factor i-33 90.0 90.0 o.o i-3 I.OOO t> - 0O = ig'o <*> = 3! A V + II, A V v + VL f. A V + *'[ 1 km km km km km km 4196.699 0.152 1.990 2.123 15-07 0.136 1-779 1.911 14.04 0.114 .491 1.614 13-23 4I97-2S7 0.146 1.909 2.O42 14-50 0.134 -753 1.885 13-85 0.116 .516 1.639 13-44 4203.730 0.146 1.906 2.039 14.48 0.137 785 .917 14.09 0.119 552 I-675 13.73 4209.144 0.148 1.928 2.o6l 14.63 0.142 -851 983 14.58 0.122 -584 1.707 13-99 4216.136 0.150 1.949 2.082 14.78 0.138 .791 923 14.13 0.116 .510 1.623 13-31 4220.509 0.152 1.972 2.105 14.94 0.145 .879 .on 14.78 0.126 -633 I-756 14.40 4232.887 0.150 1-937 2.070 14.70 0.142 -834 .966 14-45 O.I2I 555 1.678 13.76 42S7-8iS 0.153 1-953 2.086 14.81 0.146 .866 .998 14.69 0.126 .604 1.727 14.16 4258.477 0.152 1.941 2.074 14.72 0.145 .851 1.983 14.58 0.119 5i7 1.640 13-44 4265.418 0.148 1.885 2.0l8 14-33 0.141 793 1-925 14.15 O.I22 553 1.676 13-74 4266.081 0.148 1.885 2.018 14-33 0.141 .792 1.924 14.14 0.122 -553 1.676 13-74 4268.915 0.153 1-947 2.o8o 14-77 0.149 -893 2.025 14.88 0.123 -563 1.686 13.82 4276.836 0.146 1.852 1.985 14.09 0.142 799 1.932 14.20 O.II9 .510 1-633 13-39 4284.838 0.148 1.872 2.005 14.23 0.145 -833 1.965 14.44 O.IlS 490 1.613 13.22 4287.566 0.151 1.906 2.039 14.48 0.147 -856 1.988 14.61 O.II7 478 i. 60 1 13.12 4288.310 0.151 1.906 2.039 14.48 0.142 .790 1.922 14-13 O.I24 .564 1.687 13-83 4290.377 0.151 1.905 2.038 14.47 0.141 .780 1.912 14.05 O.II8 1.488 1.611 13.21 4290.542 0.159 2.005 2.138 15.18 0.148 865 1.997 14.68 0.120 1.509 1.632 13.38 4291.630 0.161 2.029 2.162 15-35 0.142 .790 1.922 14.13 O.I 21 1.522 1.645 13.49 4294.936 0.156 1.963 2.096 14.88 0.147 .850 1.982 14-57 O.I 2O 1-507 1.630 13-36 #- 45?o = 74?9 4196.699 0.084 1.092 1.197 I2.O2 0.056 0-739 0.819 11.63 0.032 0.432 0.482 13.14 4197.257 0.088 I-I53 1.258 12.63 0.059 0.772 0.852 12.10 O.O29 0-394 0.444 12. IO 4203.730 0.082 1.069 1.174 11.79 0.060 0.782 0.862 12.24 0.034 0-457 0.507 13.82 4209.144 0.095 1.238 1.338 13-43 0.060 0.778 0.858 12. l8 0.030 0.404 0-454 12.37 4216.136 0.086 1.118 1.223 12.28 0.06 1 0.794 0.874 12.41 0.032 0.430 0.480 13.08 4220.509 0.092 1.190 1.295 13.00 0.058 0.752 0.834 11.84 O.O29 0-392 0.442 12.05 4232.887 0.094 i. 216 1.321 13.26 0.056 0.706 0.786 ii. 16 O.O28 0-375 0.425 11.58 4257-815 0.092 1.176 1.281 12.86 0.059 0.749 0.829 11.77 O.026 0-343 0-393 10.71 4258.477 0.092 1.174 1.279 12.84 0.060 0.768 0.848 12.04 0.034 0.449 0.499 13.60 4265.418 0.093 1.185 1.290 12.95 0.06 1 0.778 0.858 12. l8 0.034 0.448 0.498 13-57 4266.081 0.096 i. 220 I-325 13-30 0.058 0-737 0.817 1 1. 60 0-035 0.462 0.512 13-95 4268.915 0.092 1.169 1.274 12.79 0.060 0.758 0.838 11.90 0.028 0.369 0.419 11.42 4276.836 0.096 i. 218 I.323 13-28 0.058 0.736 0.816 "59 O.O28 0.369 0.419 11.42 4284.838 0.096 i. 216 1.321 13.26 0.058 0-734 0.814 11.56 0.032 0.427 0.47.7 13.00 4287.566 0.088 1.114 1.219 12.24 0.056 0.705 0.783 11.15 0.031 0.408 0.458 12.48 4288.310 0.084 1.062 1.167 11.72 0.060 0.751 0.831 11.80 0.030 0-393 0.443 12.07 4290.377 0.093 1.174 1.279 12.84 0.046 0.685 0.765 10.86 0.031 0.408 0.458 12.48 4290.542 0.096 1. 211 1.316 13.21 0.048 0.730 0.810 11.50 0.037 0.483 0-533 14-53 4291.630 0.091 I.I48 1-253 12.58 0.059 0-743 0.823 11.69 0.033 0-433 0.483 13.16 4294.936 0.093 I-I73 1.278 12.83 0.058 0-733 0.813 "54 0.036 0.470 0.520 14.17 28 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS or 1906-1907 -Continued. Plate <> 30. 1906, Oct. 19, n h io m G. M. T. Measured by A. on G. Distance from Limb 3.6 mm. Quality, good. P-f 7T t> T\ sec') a 205.6 O 14.9 I 5 '.8 74.2 2O.4 1.067 o-o I3I.2 29.9 3-3 59-7 10.8 1.018 p -26.2 44-9 45-2 44.8 7-7 1.009 D 5-4 59-9 60.0 30.0 6-3 1. 006 Diameter 171.9 mm 74-9 75- 15.0 S.6 1. 005 Factor 1.044 89.9 89.9 O.I 5-4 1.005 = 0I *- is!o = 3! A H 11 + 1! l A V 11+ Dj f A D + ! km km km km km km 4196.699 0.148 1.967 2.106 14.95 0.136 1. 808 1-947 14-31 0.114 .516 1.642 13.46 4I97-257 0.148 1.966 2.105 14.94 0.136 1.807 1.946 14.30 O.I I 2 -489 1.615 13-24 4203.730 0.148 1.962 2.IOI 14.92 0.138 1.830 1.969 14.47 0.116 540 1.666 13.66 4209.144 0.148 1.958 2.097 14.89 0.136 1-799 1.938 14.24 0.116 537 1.663 13-63 4216.136 0.146 1.926 2.065 14.66 0-135 1.781 1.920 14.11 0.113 .492 1.618 13.26 4220.509 0.148 J-949 2.088 14.82 0.138 1.817 1.956 14-38 0.118 555 1.681 13-78 4232.887 0.150 1.966 2.105 14.94 0.137 .796 1-935 14.22 0.118 548 1.674 13-72 4257-8I5 0.150 1.946 2.085 14.80 0-139 .803 1.942 14.27 0.120 558 1.684 13.80 4258.477 0.149 1-933 2.072 14.71 0.138 790 1.929 14.18 O.II9 1-545 i. 66 1 13.62 4265.418 0.150 1.941 2.o8o 14-77 0.138 .786 1.925 14-15 O.II8 1.528 1.654 13-56 4266.081 0.150 1.941 2.080 14-77 0.138 .786 1-925 14-15 O.IlS 1.528 1.654 13-56 4268.915 0.152 1.964 2.103 14-93 0.140 .809 1.948 14.32 O.IlS -526 1.652 13-54 4276.836 0.148 1.905 2.044 14-51 0.138 777 1.916 14.08 0.116 .496 1.622 13-30 4284.838 0.150 I-925 2.064 14.65 0.139 785 1.924 14.14 0.118 .516 1.642 13.46 4287.566 0.152 1.949 2.088 14.82 0.139 .782 1.921 14.12 0.117 .502 1.628 13-35 4288.310 0.150 I-923 2.O62 14.64 0.138 .769 1.908 14.02 0.118 514 1.640 13-44 4290.377 0.148 1.896 2-035 14-45 0.140 793 1.932 14.20 0.116 .487 1.613 13.22 4290.542 0.148 1.896 2-035 14-45 0.139 .780 1.919 14.10 0.118 513 1.639 13-44 4291.630 0.149 1.907 2.046 14-52 0.140 793 1.932 14.20 0.118 512 1.638 13.43 4294.936 0.148 1.892 2.031 14.42 0.144 .841 1.980 14-55 0.118 .510 1.636 13-41 = 44! = S9?7 4, = 74?2 4196.699 0.090 .201 1.308 13.08 0-057 0.767 0.847 11.92 O.O22 0.311 0.358 9-33 4I97-2S7 0.090 .2OI 1.308 13.08 0.054 0.713 0-793 ii. 16 0.026 0.372 0.419 10.93 4203.730 0.093 .238 1-345 13-45 0.056 0.752 0.832 11.71 0.028 0.400 0.447 11.66 4209.144 0.092 .222 1.329 13.29 0.058 0.777 0.857 12.06 0.023 0-321 0.368 9.60 4216.136 0.089 .179 .286 12.86 0.056 0.750 0.830 11.68 0.024 0.342 0.389 10.14 4220.509 0.092 .217 324 13.24 0.058 0-774 0.854 12.02 0.026 0-357 0.404 11.32 4232.887 0.091 .198 305 13-05 0.058 0.770 0.850 11-97 O.O26 0.364 0.411 10.72 4257-815 0.090 -173 .280 12.80 0.060 0.789 0.869 12.23 O.O28 0.391 0.438 11.42 4258.477 0.092 .199 -306 13.06 0.059 0.776 0.856 12.05 0.028 0.385 0.432 11.26 4265.418 0.094 .221 -328 13.28 0.060 0.787 0.867 12.20 0.028 0.387 0-434 11.32 4266.081 0.096 1.247 354 13-54 0.060 0.787 0.867 12. 2O 0.028 0.389 0.436 n-37 4268.915 0.096 1-245 -352 13-52 0.059 0-773 0-853 12. OI O.O26 0-354 0.401 10.46 4276.836 0.093 1.203 .310 13.10 0.058 0.756 0.836 11.77 O.O27 o.374 0.421 10.98 4284-838 0.096 1.238 345 13-45 0.058 0-754 0.834 11-74 0.026 0.348 0-395 10.30 4287.566 0.095 1.223 330 13-30 0.058 0-753 0.833 "73 0.030 0.403 0.450 n-73 4288.310 0.094 1. 211 -318 13.18 0.059 0.766 0.846 n. 91 O.O26 0.348 0-395 10.30 4290-377 0.096 1-235 342 13-42 0.058 0.752 0.832 11.71 O.O27 0.362 0.409 10.66 4290.542 0.097 1.247 354 13-54 0.058 0.752 0.832 11.71 0.030 0.413 0.460 11.99 4291.630 0.096 1-235 -342 13-42 0.058 0-752 0.832 11.71 O.O28 0.386 0-433 11.29 4294.936 0.097 1-245 352 13-52 0.060 0.777 0.857 12.06 O.O27 0.364 0.411 10.72 RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907. TABLE 4. RESULTS FOR_!NDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907 Continued. Platew3i. 1906, Oct. 19, i2 h io m G. M. T. Measured by A. on G. Distance from Limb 3.6 mm. Quality, good. P-P seci 205 7 14.9 15.8 74.2 20.4 1.067 G-!2 131 3 29.9 3-3 59-7 10.8 1.018 P -26.2 44-9 45-2 44.8 7-7 1.009 D 5 4 59-9 60.0 30.0 6.3 i. 006 Diameter 171 9 mm 74-9 7S-0 15.0 S-6 1.005 Factor i .044 89.9 89.9 O.I S-4 1.005 = OI = 15! = 3! A V + , { A s + r, 1 A D t) + Dj km km km km km km . 4196.699 0.148 1.967 2.106 14-95 0.138 .834 1.972 14.49 O.I l6 544 .670 13.69 4I97-257 0.147 1-954 2.093 14.86 0.138 -834 1.972 14.49 0.118 569 .695 13.90 4203.730 0.149 1.976 2.115 15.02 0.140 -856 1.994 14.66 0.119 .580 .706 13.98 4209.144 0.150 1.985 2.124 15.08 0.140 .852 1.990 14.63 O.I 2O .589 715 14.06 4216.136 0.147 1.940 2.079 14.76 0.138 .820 1.958 14-39 0.118 559 685 13.81 4220.509 0.150 1.976 2.115 15.02 0.140 844 1.982 14-57 0.118 -556 .682 13-79 4232.887 0.149 1-954 2.093 14.86 0.140 .835 1-973 14.50 O.I 2O 574 .700 13-94 4257.8IS 0.150 1.946 2.085 14.80 0.143 .855 t-993 14-65 O.I 2O 559 -685 13.81 4258.47? 0.150 1.946 2-085 14.80 0.140 .816 1-954 14-36 O.I 2O 559 685 13.81 4265.418 0.150 1.941 2.080 14-77 0.142 .837 1-975 14-52 0.120 555 .681 I3-78 4266.081 0.150 1.941 2.080 14.77 0.141 .824 1.962 14.42 O.I 21 -567 .693 13.88 4268.915 0.150 1.938 2.077 14.74 0.141 .821 1-959 14.40 O.I 2O 552 .678 13-76 4276.836 0.151 1-945 2.084 14.80 0.141 .816 1-954 14-36 0.120 547 -673 13-71 4284.838 0.151 1.938 2.077 14.74 0.142 .822 1.960 14.41 O.IlS .516 .642 13.46 4287.566 0.150 1.924 2.063 14-65 0.140 .796 1-934 14.21 O.IlS 515 .641 13-45 4288.310 0.148 1.898 2.037 14.46 0.142 .820 1.958 14-39 O.I 2O 540 .666 13.66 4290.377 0.148 1.896 2-3S 14.45 0.140 793 I-93I 14.19 O.II9 .526 .652 '3-54 4290.542 0.149 1.908 2.047 14.53 0.141 .807 1-945 14-30 0. 122 565 .691 13.86 4291.630 0.150 1.921 2.060 14.62 0.140 793 I-93I 14.19 O.I 2O 539 -665 13-65 4294.936 0.150 1.918 2.057 14.60 0.140 .790 1.928 14.17 0.120 -536 .662 13.62 = 44?8 <*> = S9t7 = 74?2 4196.699 0.090 I.2OI 1.308 13-08 0.058 0.781 0.86 1 12.12 O.027 0.381 0.428 ii. 16 4I97-257 0.088 I-I73 1.280 1 2.80 0.060 0.808 0.888 12.50 0.030 0.423 0.470 12.25 4203.730 0.090 1.198 305 13.05 0.060 0.806 0.886 12-47 0.030 0.422 0.469 12.23 4209.144 0.089 I.I82 .289 12.89 0.060 0.806 0.886 12-47 0.034 0-477 0-524 13-66 4216.136 0.089 I.I79 .286 12.86 0.059 0.789 0.869 12.23 O.O28 0.392 0-439 n-45 4220.509 0.090 I.I90 297 12.97 0.058 0-774 0.854 I 2. 02 0.031 0-433 0.480 12.52 4232.887 0.088 I-I59 .266 12.66 0.061 0.810 0.800 12.52 0.028 0.390 0-437 n-39 4257-815 0.091 1.185 .292 12.92 0.06 1 0.802 0.882 12.41 0-033 0.454 0.501 13.06 4258-47? 0.090 I.I72 279 12.79 0.062 0.815 0.895 12-59 0.030 0.413 0.460 11.99 4265.418 0.088 I-I43 .250 12.50 0.060 0.787 0.867 12. 2O 0.028 0.384 0-431 11.24 4266.081 o.ooo 1.169 .276 12.76 0.059 0-773 0-853 I2.OO 0.030 0.412 0-459 11.97 4268.915 0.091 1.181 .288 12.88 0.060 0.786 0.866 12.19 0.030 0.411 0.458 11.94 4276.836 o.ooo 1.164 .271 12.71 0.060 0.784 0.864 12.16 0.026 0-356 0.403 10.51 4284.838 0.089 1.147 254 12.54 0.060 0.781 0.86 1 12.12 0.030 0.409 0.456 11.89 4287.566 0.090 I.I59 .266 12.66 0.060 0.781 0.861 12.12 O.O27 0.367 0.414 10.79 4288.310 0.090 I-I59 .266 12.66 0.060 0.780 0.860 12. IO 0.030 0.409 0.456 11.89 4290.377 0.088 1.131 -238 12.38 0.060 0.780 0.860 12. IO 0.028 0.381 0.428 ii. 16 4290.542 0.089 I-I45 -252 12.52 0.059 0.765 0.845 11.89 0.030 0.408 0-455 11.86 4291.630 0.089 1.144 251 12.51 0.059 0.765 0.845 11.89 O.O28 0.381 0.428 ii. 16 4294.936 0.090 I-I55 .262 12.62 o.ooo 0.778 0.858 12.07 0.027 0.366 0-413 10.77 The results for Plate w 35 are given on page 34. 30 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOP1C METHODS. TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907 Continued. Platew36. 1906, Nov. ii, io h I5 m G. M. T. Measured by A. on G. Distance from Limb 2.2 mm. Quality, good. P-P secy Q 228.6 iS-5 15-8 74-2 12.6 I.O2I 0-0 154-2 3-S 3-7 59-3 6.2 1. 006 P -22.6 45-5 45-4 44.6 4.6 1.003 D 3-i 60.5 60.6 29.4 3.6 I.OO2 Diameter 171.6 mm 75-5 75-5 14-5 3-2 1.002 Factor 1.027 9-5 90.5 -0-5 3.1 1.002 = -o?5 = Ml* = *0A _ A V . + ,, i. A V V + Dj 1 A V H-,, 1 km km km km . km km a 4196.699 0.148 1.929 2.670 14.70 0.143 1.865 2.005 14.70 0.119 552 1.682 13.69 4197-257 0.150 1-955 2.096 14.88 0-143 1.864 2.004 14.69 0.119 551 1.681 13.69 4203.730 0.151 963 2.104 14.94 0.141 1.834 1.974 14-47 O.I 2O .560 1.690 13-76 4209.144 0.152 973 2.114 15.01 0-145 I.88I 2.O2I 14.81 O.I22 .583 1-713 13-95 4216.136 0.151 954 2-095 14.87 0.144 1.864 2.004 14.69 0.120 553 1-683 13.70 4220.509 0.151 951 2.092 14-85 0-145 1-873 2.OI3 14-75 O.I2I -563 1-693 13-78 4232.887 0.151 .942 2.083 14.79 O.I4S 1.865 2.005 14.70 O.I 22 568 1.698 13.82 42S7.8I5 0.151 .921 2.062 14.64 0.145 1.845 1.985 14-55 0.123 -565 1.695 13.80 4258.477 0.153 947 2.088 14.82 0.145 I.845 1.985 14-55 O.I2I 539 1.669 13-59 4265.418 0.152 .928 2.069 14.69 0.144 1.828 1.968 14.42 O.I22 548 1.678 13-66 4266.081 0.152 .928 2.069 14.69 0.145 1.840 1.980 14-51 O.I 2O 523 1-653 13.46 4268.915 0.152 .926 2.067 14.67 0.144 1.825 1.965 14.40 O.I2I 533 1.663 13-54 4276.836 0.151 .908 2.049 14-55 0.146 1.844 1.984 14-54 O.I2I -528 1.658 13-5 4284.838 0.152 .914 2.055 14-59 0.145 1.826 1.966 14.41 O.I 2O -5" 1.641 13-36 4287.566 0.151 .900 2.041 14.49 0.143 1-799 1-939 14.21 O.I2I .522 1.652 13-45 4288.310 0.151 .899 2.040 14.48 0.144 1.811 I-95I 14.30 O.I2I .522 1.652 13-45 4290.377 0.152 .910 2.051 14.56 0-145 1.821 1.961 14-37 O.I 20 .508 1.638 13-34 4290.542 0.151 1.898 2.039 14.48 0-145 1.821 1.961 14-37 O.I2I 1.520 1.650 1.3-43 4291-630 0.150 1.884 2.025 14.38 0.145 1.821 1.961 14-37 0.122 1-532 1.662 13-53 4294-936 0.150 i. 88 1 2.022 14-36 0.145 1.819 J-959 14.36 0.122 1.529 1.659 13-51 = 4* = s*- = ^ 4196.699 0.089 1.162 273 12.69 0.057 0.746 0.831 11.56 O.O28 0.372 0.425 11.08 4197-257 0.089 1.161 .272 12.68 0.058 0-758 0.843 11.72 0.030 0.398 0.451 11.76 4203.730 0.090 1.171 .282 12.78 0.058 0-757 0.842 11.71 0.030 0.380 0-433 11.29 4209.144 0.089 I-I55 .266 12.62 0.060 0.782 0.867 12. 06 0.030 0.396 0-449 11.71 4216.136 0.089 1.152 .263 12.59 0.057 0.741 0.826 11.49 O.O29 0.382 0-435 "34 4220.509 0.089 .150 .261 12-57 0.060 0.778 0.863 I2.OO 0.030 0-395 0.448 11.68 4232.887 0.089 145 .256 12.52 0.059 0.761 0.846 11.76 0.031 0.406 0-459 11.97 4257-815 0.090 .146 257 12-53 0.062 0.792 0.877 12. 2O 0.032 0.415 0.468 12.17 4258.477 0.090 .146 257 12.53 0.06 1 0.779 0.864 12. OI 0.031 0.401 0-454 11.84 4265.418 0.089 .130 .241 12.37 0.060 0.764 0.869 I 2. 08 0.033 0.427 0.480 12.52 4266.081 0.090 143 254 12.50 0.060 0.764 0.849 II.8I 0.032 0.413 0.466 12.15 4268.915 0.089 .129 .240 12.36 0.059 0.750 0.835 ii. 61 0.032 0.413 0.466 12.15 4276.836 0.091 151 .262 12.58 0.062 0.786 0.871 12. II O.O29 0-373 0.426 ii. ii 4284.838 0.090 '34 245 12.41 0.060 0.758 0.833 11.58 0.031 0-397 0.450 "73 4287.566 0.090 133 244 12.40 0.06 1 0.770 0.855 11.89 0.029 0-371 0.424 1 1. 06 4288.310 0.089 1. 121 232 12.28 0.061 0.769 0.854 11.88 0.032 0.410 0.463 12.07 4290.377 0.090 I.I32 243 12.39 0.059 0.744 0.829 "S3 0.031 0.396 0-449 11.71 4290.542 0.090 I.I32 243 12.39 0.060 0-757 0.842 11.71 0.030 0.383 0.436 n-37 4291.630 0.088 1.106 .217 12.13 0.062 0.782 0.867 12.06 0.032 0.409 0.462 12.05 4294-936 0.09 1 1.142 -253 12.49 0.060 0-755 0.840 11.68 0-033 0.422 0-475 12.39 RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907. TABLE 4. RESULTS JOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907 Continued. Plate w 37. 1906, Nov. n, io h 40 G. M. T. Measured by A. on G. Distance from Limb 2.2mm. Quality, good. f-P sec 11 228.6 iS-7 16.0 74.0 "5 I.O2I Q-a IS4-2 3-7 30.8 59-2 6.2 I. OO6 P -22.6 45-7 45.8 44.2 4-4 1.003 D 3-i 60.7 60.7 29-3 3-6 I.OO2 Diameter 171.6 mm 75-7 7S-7 14-3 3-2 I.OO2 Factor 1.027 90.7 90.7 -0.7 3-1 1.002 = - !? = I4!s = 293 X A t) + , i. A V +! A V ft, { km km o km km km km 4196.699 0.150 1.960 2.IOI 14.92 0-143 1.867 2.007 14.71 O.I 2O 569 1.699 13.84 4I97-2S7 0.149 1.942 2.083 14-79 0.142 1.850 1.990 14-59 O.I2I 574 1.704 13.88 4203.730 0.149 943 2.084 14.80 0.142 1.849 1.929 14.58 [0.122 .581 1.711 13-94 4209.144 0.15-' .968 2.II9 15-04 0.142 1-843 1-973 14.46 O.I22 -578 1.708 13.92 4216.136 0.150 936 2.077 14-75 0.142 1-833 1-973 14.46 O.I22 584 1.714 13-97 4220.509 0.151 953 2.094 14.87 0.142 I-835 1-975 14.48 0. 122 571 1.701 13.86 4232.887 -i54 .980 2. 121 15.06 0.143 1.839 1.979 14.51 0.122 571 1.701 13.86 4257.815 0.152 934 2.075 14-73 0-143 1.814 1-954 14.32 O.I22 552 1.682 13-71 4258.477 0.152 930 2.071 14.70 0.143 1.817 1-957 14.34 O.I22 -557 1.687 13-75 4265.418 0.150 .908 2.049 14-55 0.143 1.812 1-952 14.3! 0.122 .548 1.678 13-67 4266.081 0.153 937 2.078 14-75 0.143 1.812 1-952 14.31 O.I 22 -548 1.678 13.67 4268.915 0.153 .942 2.083 14-79 0.143 1.815 1-955 14-33 O.I 22 .546 1.676 13.66 4276.836 0.152 .926 2.067 14.67 0.143 1. 806 1.946 14.26 0.123 554 1.684 13-72 4284.838 0.152 909 2.O5O 14-55 0.144 1.810 1.950 14.29 0.123 556 1.686 13-74 4287.566 0-153 930 2.071 14.70 0.143 t-799 1-939 14.21 0.123 -543 1-673 13-63 4288.310 0.152 .916 2.057 14.60 0.143 1.798 1.938 14.20 0.123 -545 I.675 13-65 4290.377 0.151 903 2.044 14-51 0.143 1.799 1-939 14.21 0.123 543 1-673 13-63 4290.542 0.152 915 2.056 14.60 0.143 1-795 1-935 14.18 0.123 546 1.676 13.66 4291.630 0.151 .897 2.038 14-47 0.142 1.778 1.918 14.06 0.123 548 1.678 13.67 4294.936 0.152 .901 2.O42 14.50 0.142 1.780 1.920 14.07 0.122 534 1.664 13-56 = 44? 2 = S9t2 = 74! 4196.699 0.090 1.174 .285 12.72 0.062 0.806 0.891 12-35 0.030 0.404 0-457 11.77 4I97-257 0.089 1.166 .277 12.65 0.06 1 0.796 0.88 1 12.21 0.030 0-393 0.446 11.49 4203.730 0.089 1.166 277 12.65 0.062 0.814 0.899 12.46 0.031 0.411 0.464 "95 4209.144 0.091 1.179 .290 12.77 0.062 0.803 0.888 12.31 0.032 0.426 0.479 12.34 4216.136 0.090 1.171 .282 12.70 0.061 0.793 0.878 I2.I? 0.031 0.414 0.467 12.03 4220.509 0.091 1.174 .285 12.73 0.062 0.804 0.889 12.32 0.030 0-395 0.448 "54 4232.887 0.092 1.190 .301 12.89 0.062 0.806 0.891 12-35 0.032 0.420 0-473 12.18 4257-8I5 0.092 1.169 .280 12.68 0.063 0.805 0.890 12-34 O.O32 0.421 0.474 12.21 4258-477 0.088 1.126 237 12.25 0.064 0.822 0-907 12.57 0.032 0.415 0.468 12.05 4265.418 0.091 1.158 .269 12.57 0.062 0-795 0.880 12. 2O 0.033 0.422 0-475 12.23 4266.081 0.090 1.148 -259 12.47 0.061 0.775 0.860 11.92 O.O3 I 0.404 0-457 11.77 4268.915 0.091 I-I57 .268 12.56 0.06 1 0.776 0.86 1 "93 0.032 0.409 0.462 11.90 4276.836 0.090 I-I33 244 12.32 0.062 0.781 0.866 12. OO 0.030 o-39i 0-444 11.44 4284.838 0.093 1.174 -285 12.72 0.062 0.779 0.864 11.97 0.032 0.406 0.459 11.82 4287.566 0.090 1.128 -239 12.27 0.062 0.786 0.871 I2.O7 0.032 0-415 0.468 12.05 4288.310 0.090 1.138 249 12.37 0.062 0.786 0.871 I2.O7 0.031 0-394 0.447 11.51 ' 4290-377 0.089 1.117 .228 12. l6 0.062 0.777 0.862 "PS 0.032 0.405 0.458 II.80 4290.542 0.090 I-I37 .248 12.36 0.063 0.789 0.874 12. II 0.031 0.400 0-453 11.67 4291.630 0.091 1.149 .260 12.48 0.062 0.782 0.867 I 2. 02 0.032 0.405 0.458 11.80 4294.936 0.091 1.144 -255 12.43 0.062 0.780 0.865 11.99 0.032 0.411 0.464 "95 32 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907 Continued. Plate w 38. 1906, Nov. n, n h o m G. M. T. Measured by L. on T. Distance from Limb 2.2 ram. Quality, good. P-P O 228.6 G-n 154.2 P -22.6 D 3-1 Diameter 171.6 mm Factor 1.027 15-7 16.0 74.0 ii-S i. 02 1 30.7 30.8 59- 2 6.2 i. 006 45.7 45-8 44.2 4-4 1.003 60.7 60.7 29-3 3-6 i. 002 75.7 7S-7 14-3 3-2 i. 002 90.7 90.7 -0.7 3-i i. 002 *- -* ,- .4t3 = 29.3 A t) . + ,, 1 A V , + ,, A V V ~\~ V. * 4196.699 0.148 km 1.926 km 2.067 14.68 0.138 km .798 km 1.938 14.20 0.116 km 1.511 km 1.641 13-36 4197-257 0.148 .926 2.067 14.68 0.142 .848 1.988 14.56 0.118 1.536 1.666 13-56 4203.730 0.152 974 2.II5 I5.O2 0-145 .883 2.023 14.82 O.I 22 1.586 1.716 13-97 4209.144 0.151 957 2.098 14.90 0.142 .840 .980 14-50 O.I24 1.558 1.688 13-74 4216.136 0.148 .914 2.055 14.59 0.137 .771 .911 14.00 0.118 1.526 1.656 13.48 4220.509 0.153 974 2.II5 I5.O2 0.145 .868 .008 14.71 O.I24 1.601 I-73I 14.09 4232.887 0.150 .928 2.069 14.69 0.140 .801 .941 14.22 O.I 2O 1-542 1.672 13.61 4257.815 0.156 .986 2.127 15.10 0.146 .822 .962 14-37 0.126 i. 608 1.738 14-15 4258.477 0.148 .884 2.025 I4.38 0.142 .804 944 14.24 O.I2I i.54o 1.670 13.60 4265.418 0.152 .928 2.069 14.69 0.144 .826 .966 14.40 O.I22 1.548 1.678 13.66 4266.081 0.156 .978 2.II9 15.04 0.148 .874 .014 14.76 O.I24 1.568 1.698 13-82 4268.915 0.150 .901 2.042 14.50 0.142 797 937 14.19 O.II9 1.508 1.638 13-33 4276.836 0.156 .970 2. Ill 14.99 0.143 .807 947 14.26 O.I2I 1-529 1.659 i3-5i 4284-838 0.153 930 2.071 14.70 0.142 .790 930 14.40 O.I 2O 1-513 1-643 13-38 4287.566 0.155 950 2.091 14.85 0.145 .828 .968 14.42 0.122 1-537 1.667 13-57 4288.310 0.154 .940 2.081 14.78 0.147 .848 .988 14-56 0.124 1.561 1.691 13-77 4290-377 0.156 963 2.IO4 14.94 0.140 .762 .902 13-94 0.123 1-547 1.677 13-65 4290.542 0.151 .899 2.040 14.48 0.144 .812 952 14.3 O.I 2O 1.511 1.641 13-36 4291.630 0.154 935 2.076 14-74 0.140 1.762 .902 13-94 0.124 1-559 1.689 13-75 4294-936 0.155 947 2.088 14.82 0.146 1.832 .972 14-45 0.123 1-544 1.674 13-63 = 44! 2 = * = 74!o 4196.699 0.088 1.149 .260 12.48 0.059 0.772 0.857 11.88 O.O29 0.382 0-435 11.20 4197-257 0.091 1.185 .296 12.83 0.060 0.782 0.867 12.02 0.030 0-393 0.446 11.49 4203.730 0.092 1.198 309 12.96 0.066 0.855 0.940 I3.03 0.036 0.463 0.516 13.29 4209.144 0.094 1. 221 332 I3.I9 0.062 0.805 0.890 12.34 0.034 0-445 0.498 12.83 4216.136 0.088 I.I4O 251 12.39 0.060 0.780 0.865 11.99 0.031 0.403 0.456 "75 4220.509 0.093 1.192 303 I2.9O 0.062 0.804 0.889 12.34 0.036 0.461 0.5H 13-24 4232.887 0.091 1.164 275 12.63 0.064 0.823 0.908 12.59 0.035 0-457 0.510 13.14 4257-815 0.093 1.178 .289 12.77 0.066 0.844 0.929 12.88 0.035 0.454 0.507 13.06 4258.477 0.092 I.I68 279 12.67 0.066 0.839 0.924 12.81 0.034 0.438 0.491 12.65 4265.418 0.093 1.176 .287 12.74 0.063 0.798 0.883 12.24 0-033 0.428 0.481 12.39 4266.081 0.092 1.166 277 12.65 0.065 0.827 0.912 12.64 0.032 0.413 0.466 12.00 4268.915 0.091 I-I54 .26 S 12-53 0.062 0.787 0.872 12.08 0.036 0.463 0.516 13.29 4276.836 0.093 J-I73 .284 12.71 0.063 0.796 0.881 12.21 0.032 0.411 0.464 H-95 4284.838 0.092 1.161 .272 I 2.60 0.063 0.794 0.879 12. l8 0.034 0.436 0.489 12.60 4287.566 0.094 1.181 .292 12.79 0.065 0.823 0.908 12-59 0.032 0.410 0.463 n-93 4288.310 0.094 1.181 .292 12.79 0.065 0.819 0.904 12-53 0.038 0.483 0.536 13.82 4290.377 0.093 1.170 .281 12.69 0.064 0.808 0.893 12.38 0.034 0.436 0.489 12.60 4290.542 0.093 1.170 I.28l 12.69 0.063 0.794 0.879 12.18 0.031 0-395 0.448 11-54 4291.630 0.092 I.I59 1.270 12.58 0.062 0.783 0.868 12.03 0-035 0-443 0.496 12.78 4294-936 0.093 1.168 1.279 12.67 0.070 0.880 0.965 13-38 0.033 0.420 0-473 12.18 RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907. 33 TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907 Continued. Plate w 39. 1906, Nov. n, n h i$ m G. M. T. Measured by L. on T. Distance from Limb 2.2 mm. Quality, good. Q 228.7 0-n 154-3 P -22.6 D 3.1 Diameter 171.6 mm Factor 1.027 p-p 7T n secf o o o 15-7 16.0 74-o n.6 I.O2I 30.7 30.8 59-2 6.1 i. 006 45-7 45-8 44-2 4-4 1.003 60.7 60.7 29-3 3-6 i. 002 75-7 75-7 14-3 3-2 1.002 90.7 90.7 -0.7 3- 1 1.002 = -o! 7 = I4!3 <#> = 2^3 A + ! 1 A r + Dj 1 A V H + Hj km km o km km km km o 4196.699 0.150 1.950 2.091 14.85 0.135 1-758 1.898 13-91 0.118 I-536 1.666 13-56 4197.257 0.150 1.950 2.091 14.85 0.137 .782 1.922 14.08 0.119 I.548 1.678 13-66 4203.730 0.152 -977 2.118 15-04 0.141 .828 1.968 14.42 O.I 20 1.560 1.690 13-76 4209.144 0.151 957 2.098 14.90 0-143 .847 1.987 14.56 0.122 1-584 1.714 13-95 4216.136 0.147 903 2.044 14-51 0.142 -837 1-977 14.48 O.IlS 1.526 1.656 13.48 4220.509 0-154 .988 2.129 15.12 0.144 853 1-993 14.60 O.I25 1.616 1.746 14.21 4232.887 0-153 .964 2.105 14.94 0.143 -837 1-977 14.48 0.122 1-567 1.697 13.82 4257-8I5 0.151 924 2.065 14.66 0.144 834 1-974 14.46 0.126 1.605 1-735 14.12 4258.477 0.153 947 2.088 14.82 0.142 .818 1.958 14-34 O.I22 1-554 1.684 13-71 4265.418 0.152 931 2.072 14.71 0.146 -844 1.984 14-35 O.I2I 1-537 1.667 13-57 4266.081 0.156 .978 2.119 15-04 0.144 .819 1-959 14-35 0.126 1.598 1.728 14.07 4268.915 0.156 977 2.118 15-04 0.144 .820 1.960 14-36 O.I22 1.548 1.678 13.66 4276.836 0.152 .919 2.060 14-63 0-143 799 1-939 14.21 0.123 1-555 1.685 13.72 4284.838 0.153 .926 2.067 14.68 0.146 -835 1-975 14-47 0.124 1-563 1.693 13-78 4287.566 0.156 .964 2.105 14.94 0.145 .825 1.965 14.40 0.123 1-549 1.679 13.69 4288.310 0-154 937 2.078 14-75 0.144 .820 1.960 14-36 O.I2I 1.522 1.652 13-45 4200.377 0-153 923 2.064 14-65 0.144 .819 1-959 14-35 O.I2I 1.521 1.651 13-44 4290.542 0.152 913 2.054 14.58 0.148 -859 1-999 14-65 O.I24 1.561 1.691 13.77 4291.630 0.155 947 2.088 14.82 0.144 .818 1.958 14.35 O.I2I 1.521 1.651 13.44 4294.936 0-154 932 2.073 14.72 0.145 .819 1-959 14.35 0.123 1.546 1.676 13.64 = 44!* = 59!* * = 74? 4196.699 0.088 .170 .281 12.68 0.059 0.772 0.857 11.88 0.030 0.398 0-451 11.52 4197-257 0.088 .170 .281 12.68 0.060 0.792 0.877 12. 16 0.029 0.387 0.440 "33 4203.730 0.092 195 .306 "93 0.063 0.821 0.906 12.56 0.034 0.448 0.501 12.90 4209.144 0.095 .231 -342 13-39 0.064 0.831 0.916 12.70 0.034 0.446 0.499 12.85 4216.136 0.089 153 .264 12.51 0.061 0.790 0.875 12.13 0.030 0.400 0-453 11.67 4220.509 0.093 .196 0.307 12.94 0.064 0.829 0.914 12.67 0.033 0.436 0.489 12.60 4232.887 0.092 .178 .289 12.76 0.063 0.812 0.897 12-43 0.036 0.470 0.523 13-47 4257.815 0.094 .192 303 12.90 0.066 0.839 0.924 12.81 0.038 0-453 0.506 13-03 4258.477 0.093 .182 293 12.80 0.064 0.8 1 8 0.903 12.52 0.033 0.427 0.480 12.36 4265.418 0.093 .180 .291 12.78 0.064 0.817 0.902 12.50 0.033 0.427 0.480 12.36 4266.081 0.093 .180 .291 12.78 0.066 0.838 0.923 12.80 0-035 0.452 0.505 13.01 4268.915 0.092 .168 279 12.67 0.064 0.812 0.897 12-43 0-033 0.426 0.479 12.34 4276.836 0.094 .187 .298 12.85 0.063 0.798 0.883 12.24 0.036 0.461 0.514 13-24 4284.838 0.094 .185 .296 12.83 0.063 0.796 0.881 12.21 0.034 0.436 0.489 12.60 4287.566 0.093 174 .285 12.72 0.065 0.820 0.905 12.54 0.036 0.460 0.513 13.21 4288.310 0.092 .160 .271 12.58 0.064 0.809 0.894 12.39 0.036 0.460 0-513 13.21 4290.377 0.091 144 255 12.43 0.064 0.809 0.894 12.39 0.032 0.410 0.463 "93 4290.542 0.093 .170 .281 12.69 0.063 0-795 0.880 12.20 0.032 0.410 0.463 "93 4291.630 0.094 183 294 12.81 0.066 0.829 0.914 12.67 0.035 0.446 0.499 12.85 4294.936 0.097 .218 329 13.16 0.064 0.804 0.889 12.32 0.035 0.446 0.499 12.85 34 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907 Continued. Plate w 35. 1906, Nov. n, io h o m G. M. T. Measured by L. onT\ Distance from Limb 2.2 mm. Quality, good. O 228.6 9-n 154-2 P -22.6 p-p 15.5 90-5 7T 15.8 74.2 90.5 -0.5 12.6 3-' sec i) I.02I i. 002 D 3.1 Diameter 171.6 mm Factor 1.027 x = -o's 74!* A V > + ! s A V i + t, I km km o km km . 4196.699 0.148 925 2.066 14.67 0.029 0.386 0-439 11-45 4197-257 0.150 950 2.091 14.85 0.030 0.397 0.450 n-73 4203.730 O.IS3 .987 2.128 15.11 0-033 0.436 0.489 12.75 4209.144 0.154 995 2.136 15.16 0.035 0.462 0-515 13-43 4216.136 0.149 .876 2.017 14-32 0.030 0-395 0.448 11.68 4220.509 0.153 974 2.II5 15.02 0.032 0.420 0-473 12.33 4232-887 0.153 .967 2.108 14.97 0-033 0.430 0.483 12.60 4257.815 0-155 973 2.114 15.01 0.034 0-437 0.490 12.78 4258.477 0.151 923 2.064 14.65 0.035 0.452 0-505 13-17 4265.418 0.152 1.927 2.068 14.68 0.034 0.436 0.489 12.75 4266.081 0.153 1.940 2.081 14-78 0-034 0.436 0.489 12.75 4268.915 0.152 1-925 2.066 14.67 0.034 0.436 0.489 12.75 4276.836 0.152 .922 2.063 14.65 0.034 0.436 0.489 12.75 4284.838 0.154 943 2.084 14-79 0.033 0.425 0.478 12.46 4287.566 0.153 925 2.066 14.67 0.034 0-435 0.488 12-73 4288.310 0.154 938 2.079 14.76 0.034 0-435 0.488 12.73 4290.377 0.150 .888 2.029 14.41 0.034 0-435 0.488 12.73 4290.542 0-153 923 2.064 14.65 0.035 0-445 0.498 12.99 4291.630 0-153 .922 2.063 14.65 0.033 0.421 0.474 12.36 4294.936 0-154 931 2.072 14.71 0.033 0.420 0-473 12-33 Plate u 39J. 1906, Dec. 18, 5 h 50 G. M. T. Measured by L. on T. Distance from Limb 4. i mm. Quality, good. O 265.9 G-n 191.5 P -8.8 P-P 59-9 74-9 89.9 59-9 74-9 89.9 30.1 1.4 secv i.ooo i.ooo i.ooo D -1.5 Diameter 175.2 mm Factor 1.049 X = o!i = IS?I = 30?i A V +! { A V JI+Dj i A V + , km km O km km . km km 4196.699 0.148 1.963 2.104 14.94 0.138 I.833 1-973 14-52 0.119 1-577 1.707 14.02 4197-257 0.148 1.963 2.104 14.94 0.138 1.833 1-973 14-52 0.120 1.587 1.717 14.10 4203.730 0.150 1.985 2.126 15-09 0.141 1.837 1.977 14.54 O.II9 1-575 I.705 14.00 4209.144 0-153 2.021 2.162 15-35 0.142 1.871 2. Oil 14.79 O.I22 1-594 1.724 14.16 4216.136 0.146 1.926 2.067 14.67 0.139 1.836 1.976 14.54 0.118 I.5S6 1.686 13.85 4220.509 0.151 1.974 2.115 15.02 0.141 1-855 1-995 14.68 0.122 1.586 1.716 14.09 4232.887 0.150 1.958 2.099 14.90 0.142 1.846 1.986 14.61 O.I22 1.582 1.712 14.06 4257.815 0.150 1-947 2.088 14.82 0.144 1.868 2.008 14-77 O.I24 1-597 1.727 14.19 4258.477 0.150 1.946 2.087 14.82 0.141 1.823 1.963 14.44 0.120 I-5S2 .682 13.82 4265.418 0.152 1.965 2.106 14-95 0.142 1.831 1.971 14-50 0.123 1-584 714 14.08 4266.081 0.156 2.016 2-157 15.31 0.143 1.850 1.990 14.64 O.I2I 1-563 693 13.91 4268.915 0.149 1.924 2.065 14.66 0.140 1.805 1-945 14-31 0.122 1-566 .696 13.93 4276.836 0.152 1.956 2.097 14.89 0.142 1-823 1.963 14.44 0.123 1.580 .710 14.05 4284.838 0.153 1.963 2.104 14.94 0.145 i. 860 2.000 14.71 O.I2I I-556 .686 13-85 4287.566 0-153 1.967 2.108 14.97 0.144 1.848 1.988 14.63 O.I22 1.562 .692 13.90 4288.310 0-154 1.972 2.113 15.00 0.141 i. 808 1.948 14-33 O.I24 1-587 .717 14.10 4290.377 0.151 1-933 2.074 14.72 0.141 1.810 1.950 14.35 O.I 2O 1-537 .667 13.69 4290.542 0.150 1.922 2.063 14.65 0-145 1.858 1.998 14.70 0.125 1-599 .729 14.20 4291.630 0.152 1-949 2.090 14.84 0.140 1.796 1.936 14.24 0.123 1-575 1-705 14.00 4294.936 0.153 1-959 2.IOO 14.91 0.142 1.815 1-955 14-38 0.122 1.560 1.690 13.88 RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907. 35 Plate TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907 Continued. 40. 1906, Dec. 18, 6 b 40 G. M. T. Measured by L. on T. Distance from Limb 4.1 mm. Quality, good. O 265.9 o-n 191.5 P -8.8 D -i. S Diameter 175.6 mm Factor 1.049 P-P 59-9 74-9 89.9 59-9 74-9 89.9 30.1 O.I i-S 1.4 sec>; 1. 000 I.OOO 1. 000 = o!i = !i <#> = is!i A V f + tlj A fl T + fl! 1 A V ! + , 1 km km o km km km km 4196.699 0.148 1.964 2.105 14.94 0.150 1.990 2.131 I5-I3 0.138 1-833 1-973 14-50 4197.257 0.148 1.964 2.105 14.94 0.150 1.990 2.131 IS-I3 0-139 1.843 1.983 14-58 4203.730 0.152 2.013 2-154 15-29 0.149 1-975 2.116 15.02 0.141 1.863 2.003 14.72 4209.144 0.149 1.966 2.107 14.96 0.150 1.984 2.125 15.09 0.141 1.805 1-945 14-30 4216.136 0.151 1.986 2.127 15.10 0.148 I-95I 2.092 14-85 0.141 1.858 1.998 14.68 4220.509 0.150 1-975 2.116 15.02 0.152 2.OOI 2.142 15.21 0.140 1.841 1.981 14-56 4232.887 0.149 1-954 2.095 14.87 0.150 1.966 2.IO7 14.96 0.141 0.846 1.986 14.60 4257.815 0.152 1.969 2. IIO 14.98 o.iSS 2.013 2.154 I5.29 0.142 1.843 1.983 14.58 4258.477 0.152 1.968 2.IO9 14-97 0.149 936 2.077 14-74 0.139 1.802 1.942 14.27 4265.418 0.150 1.940 2.081 14-77 0.151 954 2.095 14.87 0.143 1.851 1.991 14-63 4266.081 0-153 1.976 2.II7 15-03 0.152 .960 2.IOI 14.92 0.143 1.850 1.990 14.63 4268.915 0.152 1-959 2. TOO 14.91 0.150 .938 2.079 14.76 0.143 1.849 1.989 14.62 4276.836 0-153 1.971 2. 112 14.99 0.151 945 2.086 14.81 0.144 1.853 1-993 14.65 4284.838 0.152 1-953 2.094 14.87 0.152 J-953 2.094 14.87 0.142 1.824 1.964 14.44 4287.566 0.148 1.900 2.O4I 14.49 0.152 I-95I 2.092 14.85 0.140 1-797 1-937 14.24 4288.310 0.151 1-937 2.078 14-75 0.156 1.998 2.139 15-18 0.143 1.848 1.988 14.61 4290.377 0.152 1.947 2.088 14.82 0.151 1.936 2.077 14-74 0.140 1.796 1.936 14-23 4290.542 0.150 1.921 2.o62 14.64 0.151 1.936 2.077 14.74 0.144 1.844 1.984 14-58 4291.630 0.150 1.921 2.062 14.64 0.152 1.946 2.087 14.81 0.141 i. 806 1.946 14.30 4294.936 0.152 1-945 2.086 14.81 0.150 1.919 2.O6O 14.62 0.143 1.831 1.971 14.49 = isli = 3o!i = so!i 4196.699 0-139 1.843 1.983 14.58 O.I 20 592 1.722 I4-I3 0.119 1.581 1.711 14.04 4197.257 0.140 1.859 1.999 14.69 O.II9 .578 1.708 14.02 0.123 1-633 1-763 14-47 4203.730 0.141 1.867 2.007 14-75 0.123 .631 1.761 14-45 O.I22 1.616 1.746 14-33 4209.144 0-143 1.887 2.027 14.90 0.122 .610 1.740 14.28 0.120 1-584 1.714 14.06 4216.136 0.140 1.843 1.983 14.58 O.II7 541 1.671 I3-7I O.IlS I-556 1.686 13-84 4220.509 0.140 1.841 1.981 14.56 O.I 21 591 1.721 14.12 O.I 2O 1.580 1.710 14-03 4232.887 0.143 1.872 2.012 14.79 O.I 2O -561 1.691 13-88 0.122 1-597 1.727 14.17 4257.815 0.141 1.828 1.968 14.46 O.I2I 559 1.689 13.86 O.I22 1-585 1.715 14.07 4258.477 0.140 1.813 1-953 14-35 O.I24 .607 1-737 14.25 O.I22 1.581 1.711 14.04 4265.418 0.141 1.825 1.965 14.44 O.I2I .560 1.690 13-87 0.124 1.604 1-734 14-23 4266.081 0.140 1.810 1-950 14-33 0.124 .604 1-734 I4-23 0.123 1.589 1.719 14.11 4268.915 0.142 1-834 1-974 14-51 O.I 2O 547 1.677 I3-76 0.123 1.588 1.718 14.10 4276.836 0.145 1.871 2. on 14.78 O.I 22 -570 1.700 13-95 O.I22 1.566 1.696 13.92 4284.838 0.140 1.799 1-939 14-25 O.I 21 552 1.682 13.80 O.I2I 1-552 1.682 13.80 4287.566 0.144 1.848 1.988 14.61 O.I2I 551 1.681 13-79 O.I22 1-563 1.693 13.89 4288.310 0.141 1.808 1.948 14-32 O.I 20 540 1.670 13.70 O.I22 1.562 1.692 13-88 4290.377 0.140 1.796 1.936 14-23 O.II9 525 I-6S5 I3-58 O.I 2O 1.540 1.670 13.70 4290.542 0.140 1.796 1.936 14-23 O.I 21 550 i. 680 13-79 O.II7 1.499 1.629 13-37 4291.630 0.147 1.884 2.024 14.88 O.I 21 550 i. 680 13-79 O.I2I i-SSo i. 680 13-79 4294.936 0.142 1.815 1-955 14-37 O.I22 -560 1.690 13.87 O.I22 1-560 1.690 13-87 36 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907 Continued. Plate w 41. 1906, Dec. 18, 6 h so"" G. M. T. Measured by L. on T. Distance from Limb 4.1 mm. Quality, good. O 265.9 O-S2 191.5 P -8.8 D -1.5 Diameter 175.6 mm Factor 1.049 P-P 59-9 74-9 89.9 59-9 74-9 89.9 t> 30.1 15.1 O.I 1.4 secy I.OOO I.OOO I.OOO *- 0*1 *- * - X* A . + 1 A V ,-M, A t) . + ., 4196.699 0.145 km 1.927 km 2.068 14.68 0.145 km 1.927 km 2.068 14.68 0.136 km 1. 806 km 1.946 14.30 4197-257 0.146 1.938 2.079 14.76 0.144 I.9I3 2.054 14.58 0.138 1.832 1.972 14.49 4203.730 0.147 1.946 2.087 14.82 0.147 1.946 2.087 14.82 0.141 I.86I 2.OOI 14.71 4209.144 0.148 1.958 2.099 14.90 0.148 1-954 2.095 14.87 0.140 1-794 934 14.21 4216.136 0.146 1.926 2.067 14.67 0.145 1.912 2.053 14.58 0.138 1.820 .960 14.41 4220.509 0.148 1.949 2.090 14.84 0.148 1-945 2.086 14.81 0.141 1.856 .990 14-63 4232.887 0.150 1.965 2.106 14-95 0.150 1.965 2.106 14-95 0-139 1.818 958 14-39 4257-815 0-153 1.985 2.126 15.09 0.150 1.946 2.087 14.82 0.141 1.828 .968 14.46 4258.477 0.148 1.922 2.063 14-65 0.150 1.946 2.087 14.82 0.140 1.813 953 14-35 4265.418 0.152 1.969 2. no 14.98 0.152 1.968 2.109 14.97 0.142 1.836 976 14.52 4266.081 0.151 1-954 2.095 14.87 0.148 1.919 2.060 14-63 0.142 1.836 1.976 14-52 4268.915 0.151 1-952 2.093 14.86 0.149 1.928 2.069 14.69 0.142 1-835 1-975 14.52 4276.836 0.152 1.960 2.IOI 14.92 0.152 J-959 2.IOO 14.91 0.141 1.817 1-957 14-38 4284.838 0.150 1.928 2.069 14.69 0.150 1.928 2.069 14.69 0.142 1.807 1-947 14-31 4287.566 0.151 1-937 2.078 14-75 0.150 1.923 2.064 14-65 0.141 1.809 1.949 14-32 4288.310 0.152 2.092 14.85 0.151 1-933 2.074 14.72 0.140 1-794 1-934 14.21 4290.377 0.151 I-936 2.077 14-75 0.149 1.912 2-053 14.58 0.142 1.803 1-943 14.28 4290.542 0.151 1.936 2.077 14-75 0.150 1.922 2.063 14-65 0.140 1.792 1.932 14.20 4291.630 0.151 1.936 2.077 14-75 0.150 1.922 2.063 14.65 0.141 1.807 1.947 I4-3I 4294-936 0.151 1-934 2.075 14-74 0.152 1-945 2.086 14.81 0.140 1.791 I-93I 14.19 *- .,:, *- * *- 30! i 4196.699 0.136 1.806 1.946 14-30 O.I2I 1.607 1-737 14.25 0.115 525 1-655 I3-S8 4197-257 0.136 i. 806 1.946 14-30 O.I2I 1.607 1-737 14-25 0.117 551 .681 13-79 4203.730 0-139 1.840 1.980 14-55 O.I 2O 1-590 1.720 14.11 0.119 574 .704 13.98 4209.144 0.140 1.848 1.988 14.61 O.II8 -558 1.688 13-85 0.119 572 .702 13-97 4216.136 0-137 1.805 1-945 14-30 O.IlS -556 1.686 13-84 0.116 529 659 13.61 4220.509 0.138 1.814 1-954 14.36 O.IlS 554 1.684 13.82 0.120 -578 .708 14.02 4232.887 0.141 1-794 1-934 14.21 O.I 2O -571 1.701 13.96 0.119 1-561 .691 13.88 4257-815 0.142 1.843 1.983 14-58 0.122 .585 I-7I5 14.07 O.I 2O 1-554 .684 13.82 4258.477 0.140 1.812 1-952 14-34 0.123 -591 1.721 14.12 O.I2I 1-565 -695 I3-9I 4265.418 0.140 1.809 1-949 14-32 O.I2I -567 1.697 13-93 0.120 1-552 .682 13.80 4266.081 0.141 1.826 1.966 14-45 O.I2I 567 1.697 13-93 O.I22 1-576 .706 14.00 4268.915 0.141 1.824 1.964 14.44 0.123 .588 1.718 14.10 O.I 2O .681 13-79 4276.836 0.142 1.832 1.972 14.49 O.I22 574 1.704 13.98 0.123 1-583 713 14.06 4284.838 0.143 1.839 1.979 14-55 O.I22 .567 1.697 13-93 O.II9 1-530 .660 13.62 4287.566 0.141 1.807 1.947 14-31 O.I22 -566 1.696 13.92 O.I22 I-57I .701 13.96 4288.310 0.141 1.807 1.947 14-31 O.I24 591 1.721 14.12 O.I2I 1.562 .692 13.88 4290.377 0.142 1.819 1-959 14.40 0.123 -577 1.707 14.01 O.I2I 1.562 .692 13-88 4290.542 0.142 1.819 1-959 14.40 0.122 -566 1.696 13.92 0.123 I-S7S 705 13-99 4291.630 0.142 1.817 1-957 14.38 O.II8 1.514 1.644 13-49 O.I22 1-565 1.695 13-91 4294.936 0-143 1.831 1.971 14.49 O.I22 1.560 1.690 13-87 O.I22 1-564 1.694 13.90 RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907. 37 TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS or 1906-1907 Continued. Plate 1046. 1906, Dec. 18, io h 30 G. M. T. Measured by L. on T. Distance from Limb 4.1 mm. Quality, good. O 266.1 O-O 191.7 P -8.8 D -1.5 Diameter 175.0 mm Factor 1.047 P-P 30.6 45-6 30.6 45-6 59-4 44.4 2.9 2.1 seen I.OOI I.OOI = 44?4 = 44?4 = 44?4 X A f + l e A V H + Uj { A V f + Pj E km km . km km o km km o 4196.699 0.088 I.I68 .281 12.73 0.086 1.138 251 12.43 0.088 .164 1.277 12.69 4197.257 0.088 1.168 .281 12.73 0.088 1.163 .276 12.68 0.089 .178 1.291 12.83 4203.730 0.090 1.187 .300 12.92 0.090 .187 .300 12.92 0.092 .216 329 13.21 4209.144 0.090 1.186 299 12.91 0.090 .186 .299 12.91 0.092 .211 -324 13.16 4216.136 0.089 1.170 -283 12.75 0.091 .198 3" 13-03 0.088 159 .272 12.64 4220.509 0.091 1-193 -306 12.98 0.091 .197 .310 13.02 0.092 .208 .321 13-13 4232-887 0.092 I.2OI .314 13.06 0.093 215 .328 13.20 0.090 .176 .289 12.81 4257.815 0.093 1.205 -318 13.10 0.093 .204 317 13.09 0.092 .189 .302 12.94 4258.477 0.092 1.187 .300 12.92 0.093 .204 I-3I7 13.09 0.090 -I6 S .278 12.70 4265.418 0.095 1.226 339 13-31 0.094 1.209 1.322 13-14 0.093 .199 .312 13-04 4266.081 0.092 1.185 .298 12.90 0.092 1-185 1.298 12.90 0-092 1.188 .301 12-93 4268.915 0.092 1.182 295 12.87 0.092 1.184 1.297 12.89 0.093 1.198 3" 13.02 4276.836 0.091 1.171 .284 12.76 0.093 1.196 1.309 13.01 0.092 1.185 .298 12.90 4284.838 0.092 1.180 293 12.84 0.092 1.180 1.293 12.85 0.090 I-I59 .272 12.64 4287.566 0.096 1.231 344 13-35 0.092 1.179 1.292 12.84 0.092 1.179 .292 12.84 4288.310 0.090 I-I54 .267 12.59 0.092 1.179 1.292 12.84 0.091 1.168 .281 12.73 4290.377 0.090 1.149 .262 12.54 0.093 1.163 1.276 12.68 0.090 I-I54 277 12.69 4290.542 0.089 1.139 .252 12.44 0.091 1.149 1.262 12-54 0.092 1.178 .291 12.83 4291.630 0.091 1.164 .279 12.71 0.092 1.178 1.291 12.83 0.091 1.167 .280 12.72 4294.936 0.092 1.177 .290 12.82 0.094 1.198 1.311 13-03 0.092 1.177 .290 12.82 = S9!4 = S9A = S9t4 4196.699 0.058 0.766 0.852 11.88 0.058 0.768 0-854 11.91 0.060 0-793 0.879 12.26 4197.257 0.056 0.736 0.822 11.46 0.06 1 0.804 0.890 12.41 0.057 0-757 0.843 11.76 4203.730 0.060 0.792 0.878 12.25 0.06 1 0.803 0.889 12.40 0.064 0.844 0-930 12.97 4209.144 0.062 0.8 1 6 0.902 12.58 0.062 0.816 0.902 12.58 0.062 0.816 0.902 12.58 4216.136 0.060 0.790 0.876 12.22 0.06 1 0.801 0.887 12.37 0.058 0.764 0.850 11.85 4220.509 0.062 0.814 0.900 12-55 0.062 0.814 0.900 12.55 0.061 0.803 0.889 12.40 4232.887 0.062 0.812 0.898 12.52 0.063 0.822 0.908 12.66 0.065 0.848 0-934 13-03 4257.815 0.064 0.828 0.914 12-74 0.064 0.825 0.911 12.71 0.062 0.802 0.888 12.38 4258.477 0.06 1 0-793 0.879 12.26 0.062 0.800 0.886 12.36 0.062 0.839 0.925 12.90 4265.418 0.065 0.847 0-933 13.01 0.06 1 0.788 0.874 12.19 0.064 0.829 0.915 12.76 4266.081 0.064 0.827 0.913 12-73 0.064 0.824 0.910 12.69 0.065 0.839 0.925 12.90 4268.915 0.063 0.812 0.892 12.44 0.065 0.838 0.924 12.89 0.063 0.809 0.875 12. 2O 4276.836 0.062 0.802 0.888 12.38 0.062 0-797 0.883 12.32 0.062 0.797 0.883 12.32 4284.838 0.06 1 0.788 0.874 12.19 0.065 0.831 0.917 12.79 0.063 0.806 0.892 12.44 4287.566 0.063 0.809 0.895 12.48 0.063 0.805 0.891 12.43 0.061 0.781 0.867 I2.O9 4288.310 0.062 0-795 0.881 12.29 0.064 0.820 0.906 12.64 0.062 Q-795 0.881 12.29 4290.377 0.060 0.770 0.856 11.94 0.062 0.794 0.880 12.27 0.063 0.805 0.891 12.43 4290.542 0.061 0.784 0.870 12.13 0.062 0-794 0.880 12.27 0.063 0.805 0.891 12.43 4291.630 0.062 0-794 0.880 12.27 0.063 0.804 0.890 12.41 0.062 0-794 0.880 12.27 4294.936 0.062 0.794 0.880 12.27 0.06 1 0.780 0.866 12.08 0.063 0.804 0.890 12.41 38 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907 Continued. Plate w 47. 1906, Dec. 18, lo 11 50 G. M. T. Measured by L. on T. Distance from Limb 3.9 mm. Quality, good. O 266.1 o-n 191.7 P -8.8 D -1.5 Diameter 175.0 mm Factor 1.047 p P TT ij seci? 30.6 30.6 59.4 2.9 i.ooi 38.1 38.1 51.9 2.4 i.ooi 45.6 45.6 44.4 2.1 I.OOI 54.6 54.6 35.4 1.8 i.ooo = 35t4 = 35!4 = 44t4 A D H-* ' A V . + ., A V , + 4196.699 o.i 06 km 1.410 km 1-535 13-37 O.IOI km 1.386 km 1.511 13.16 0.086 km .169 km .282 12.74 4197-257 0.107 1.417 1-542 13-43 0.103 1.366 1.491 12.99 0.088 .169 .282 12.74 4203.730 0.105 1.386 1.511 13.16 0.108 1.427 1-552 I3-52 0.092 .20? .320 13.12 4209.144 0.108 1.426 1.551 13-51 0.106 1.398 I-523 13.26 0.091 .197 .310 13.02 4216.136 0.109 1-434 1-559 13.58 0.102 1.392 I-5I7 13.21 0.090 .185 .298 12.90 4220.509 0.108 1.418 1-543 13-44 o.i 06 1-391 1.516 13.20 0.092 .209 .322 I3-I4 4232.887 0.108 I-4IS 1-540 13-41 0.104 1.405 1-530 13-33 0.091 .187 .300 12.92 4257.815 0.108 1.400 I-S2S 13.28 0.108 1-397 1-522 13.26 0.092 -205 315 13-07 4258.477 0.109 1.410 1-535 13-37 0.107 1.386 1.511 13.16 0.092 .202 315 13-07 4265.418 0.109 1.408 J-533 13-35 0.108 1-394 I-5I9 13-23 0.095 .224 1-337 13-29 4266.081 O.III 1.432 1-557 13-56 o.i 06 1.369 1-494 13.01 0.093 .2OO I-3I3 13-05 4268.915 O.II2 1-445 1-570 13.67 0.108 1-393 1.518 13.22 0.093 .199 1.312 13.04 4276.836 O.II4 1.464 1.589 13.84 O.IIO i-4i5 540 I3-4I 0.094 .207 1.320 13.12 4284.838 O.IIO 1.410 1-535 13-37 O.III 1.426 551 I3-5I 0.094 .204 I-3I7 13.09 4287.566 0.109 1-395 1.520 13-24 0.107 1-370 495 13.02 0.092 .l8o 1.293 12.85 4288.310 0.108 1-385 1.510 13-15 0.108 1.384 509 I3-I4 0.096 .229 1-342 13-34 4290.377 0.108 1.384 1.509 13-14 0.109 1-395 .520 13-24 0.092 I.I79 1.292 12.84 4290.542 0.108 1-384 1.509 13-14 0.108 1.384 509 13-14 0.092 I.I79 1.292 12.84 4291.630 0.108 1.384 1.509 13-14 0.108 1-379 504 13.10 0.093 I.I89 1.302 12.94 4294.936 O.II2 1-433 I.5S8 13-57 0.106 1-354 479 12.88 0.093 1.189 1.302 12.94 = * 9 = 5 :! 9 = S9?4 4196.699 O.072 0-955 1.056 12.15 0.073 0.967 i. 068 12.28 0.060 0-793 0.879 12.26 4197-257 0.073 0.966 1.067 12.27 0.075 0-995 1.096 12.65 0.057 0.757 0.843 11.76 4203.730 0.073 0.964 1.065 12.25 0.075 0.994 1.095 12.64 0.058 0.766 0.852 11.88 4209.144 0.074 0.977 1.078 12.40 0.074 0.978 1.079 12.41 0.064 0.849 0-935 13-04 4216.136 0.074 0.976 1.077 12.39 0.074 0.977 1.078 12.40 0.060 0.790 0.876 12.22 4220.509 0.075 0.985 i. 086 12.49 0.075 0.983 1.084 12.47 0.06 1 0.800 0.886 12.36 4232.887 0.078 1.014 1.115 12.82 0.073 0-955 1.056 12.15 0.062 0.808 0.894 12.47 4257-815 0.076 0.984 1.085 12.48 0.076 0.985 i. 086 12.49 0.064 0.828 0.914 12.75 4258.477 O.oSo 1-035 1.136 13-07 0.076 0.985 i. 086 12.49 0.065 0.846 0.932 13.00 4265.418 0.076 0.982 1.083 12.46 0.074 0-959 i. 060 12.19 0.065 0.845 0.931 12.98 4266.081 0.079 i. 020 1. 121 12.89 0.078 1.009 i. no 12.87 0.067 0.865 I3-24 4268.915 0.074 0-957 1.058 12.17 0.075 0.969 1.070 12.32 0.062 0.798 0.884 12.33 4276.836 0.079 1.017 1.118 12.86 0.074 0-953 1.054 12.13 0.062 0.797 0.883 12.32 4284.838 0.077 0.991 1.092 12.56 0.076 0.976 1.077 12.39 0.06 1 0.785 0.871 12.15 4287.566 0.078 I.OOI I.IO2 12.68 0.079 I.OIO i. in 12.88 0.065 0.833 0.919 12.82 4288.310 0.077 0.986 I.OS? 12.50 0.081 1.034 I-I35 13-05 0.064 0.819 0.905 12.62 4290.377 0.078 I.OOO I.IOI 12.67 0.080 1.023 1.124 12.93 0.064 0.819 0.905 12.62 4290.542 O.O8O 1.024 1.125 12.94 0.077 0.986 1.087 12.50 0.064 0.819 0.905 12.62 4291.630 0.079 I.OIO I. Ill 12.87 0.079 1.009 i. no 12.87 0.063 0.805 0.891 12.43 4294.936 0.075 0-959 1. 060 12.19 0.078 0.998 1.099 12.65 0.062 0-794 0.880 12.27 RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907. 39 Plate TABLE 4. RESULTS FOB INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907 Continued. 50. 1907, Feb. 3, $ h 40"" G. M. T. Measured by L. on T. Distance from Limb 3.5 mm. Quality, good. O 0-0 P D 313.8 239-4 13.0 -6.3 Diameter 174.1 mm Factor 1.042 p-p 7T 4> 1 sec 17 10.5 12.2 778 3-9 1.166 19.5 20-S 69-S 18.1 1.052 35-5 36.0 54-0 10.6 1.017 Si-5 51.8 38-2 7-9 1.009 66.5 66.7 23-3 6.8 1.008 82.3 82.5 7-5 6-3 1.006 = ?!s - 133 = 38t2 A V + ! { A V + ! A + , { km km O km km . km km e 4196.699 0.141 1.861 2.OO2 14-32 0.128 1.700 1.834 14.18 0.104 1.383 .500 13-55 4197-257 0.141 1.861 2.002 14.32 0.129 I-7I3 1.847 14.28 0.105 1-395 512 13-66 4203.730 0-143 1.888 2.O29 14-52 0.130 I.72I 1-855 14-34 0.106 1.400 517 13-70 4209.144 0.144 1.896 2.037 14-57 0.130 1.719 1-853 14-32 0.106 1-399 .516 13-70 4216.136 0.142 1.867 2.008 14-37 0.129 1.699 1.834 14.18 0.104 1-374 .491 13-47 4220.509 0.144 1.892 2-033 14-54 0.130 I.7I2 1.846 14.27 0.106 1-397 514 13-68 4232.887 0.143 1.872 2.013 14.40 0.130 '70S 1.839 14.22 0.106 i-39i .508 13.62 4257-815 0.145 1.897 2.038 14.58 0.132 1.714 1.848 14.28 0.108 1.404 521 13-74 4258.477 0.143 1-854 1-995 14.27 0.130 1.688 1.822 14.08 0.108 1-403 .520 -J3-73 4265.418 0.146 1.887 2.028 14-51 0.131 1.697 I.83I I4-I5 0.108 1-399 .516 I3-70 4266.081 0.146 i. 880 2.021 14.46 0.134 1-734 1.868 14.44 0.108 399 .516 13-70 4268.915 0.146 1.879 2.020 14.45 0.130 1.682 1.816 14.04 0.109 .402 519 I3-72 4276.836 0.145 1.863 2.OO4 14-34 0.131 1.689 1.823 14.09 0.108 390 1-507 13.61 4284.838 0.145 i. 86 1 2.OO2 14.32 0.131 1.683 1.817 14.04 O.IIO 415 1-532 13.84 4287.566 0.144 1-855 1.996 14.28 0.134 1.721 1-855 14-34 0.108 -388 I-505 13.60 4288.310 0.144 1.847 1.988 14.22 0-133 1.708 1.842 14.24 O.IIO 413 1-530 13.82 4290-377 0.144 1.847 1.988 14.22 0.131 1.681 1.815 14.03 0.107 -378 1-495 I3-5I 4290.542 0.146 1.870 2.OII 14-39 0.132 1.694 1.828 I4-I3 O.I 1 1 424 I-54I 13.92 4291.630 0.144 1.849 1-990 14.24 0.130 1.667 1.801 13.92 0.109 -397 I-SU 13-68 4294.936 0.147 i. 880 2. 02 1 14.46 0.131 1.679 1.813 14.01 0.108 -385 1.502 13-57 = 54!" <*> = 6g.S = 77!8 = 77:8* A V f + tij 1 A + , 1 A f + ! A V + , I km km km km km km km km 4196.699 0.068 0.911 I.OOI I2.0Q 0.038 0.527 0.583 |ll.82 0.015 0.232 0.266 8.94 0.016 0-253 0.285 9.64 4197-257 0.068 0.911 I.OOI I2.O9 0.039 0.541 0-597 I2.IO 0.016 0-245 0-27? 9-37 0.017 0-259 0-293 9.84 4203.730 0.069 0.923 I.OI5 12.24 0.040 0-552 0.608 12-33 0.019 0.292 0.326 10.95 0.021 0.329 0-363 12. 2O 4209.144 0.071 0.946 1.036 I2-5I 0.040 0-551 0.607 12.31 0.018 0.276 0.310 10.41 O.O2O 0.306 0.340 11.42 4216.136 0.067 0.892 0.982 11.86 0.038 0.525 0.581 11.78 0.017 0.260 0.294 9.88 O.OI7 0.260 0.294 9.88 4220.509 0.069 0.918 i. oof 12.18 0.040 0-549 0.605 12.26 0.017 0.259 0.295 9.84 0.021 0.317 0.351 11.79 4232.887 0.070 0.926 .016 12.27 0.039 0-533 0.589 11.94 0.019 0.288 0.322 10.82 O.OI? 0.264 0.29? 10.01 4257-815 0.072 0-943 03: 12.48 0.042 0.570 0.626 12.69 O.O2I 0.313 0-34/ 11.66 O.OI9 0.283 0.313 10.65 4258.477 0.069 0.906 o.ggf I2.O2 0.041 0-555 0.611 12.39 O.OlS 0.271 0.305 10.25 0-023 0-343 0-373 12.67 4265.418 0.071 0.928 .01 i ! 12.30 0.041 0-554 o.6ic 12-37 O.OlS 0.270 0.304 IO.2I 0.019 0.282 0.316 10.62 4266.081 0.073 0.952 .04; 12-59 0.043 0-577 0.633 12.83 O.02I 0-3I3 0-347 11.66 O.O22 0-325 0-35? 1 2.06 4268.915 0.070 0.912 .00; 12. II 0.039 0.527 0-583 11.82 0.018 0.270 0.304 IO.2I O.O2I 0.322 0-35? 11.96 4276.836 0.070 0.912 .00: 12. II 0.040 0.538 0-595 1 2.O6 O.O2O 0.299 0-333 11.19 0.022 0.324 0-35* 12.03 4284.838 0.073 0.948 .03* ! 12.54 0.041 o.SSi 0.607 12.30 0.019 0.283 o.3i/ 10.64 O.O2O 0.301 0-33= 11.25 4287.566 0.072 0.936 .026 12.39 0.042 0.565 0.619 12-55 0.018 0.269 0-303 10.18 O.OI9 0.285 0-31? 10.72 4288.310 0.072 0-935 .02; 12.38 0.040 0-537 0.593 12. 02 0.019 0.282 0.316 10.62 0.019 0.280 0.314 10.55 4290.377 0.073 0.944 034 [ 12.49 0.040 0-537 0-593 1 2. 02 0.019 0.282 0.316 10.62 O.O2O 0.298 0-33= 11.15 4290.542 0.072 0.932 .02i 12.35 0.041 0.548 0.605 12.26 0.018 0.268 0.302 10.15 0.023 0-345 0-37? 12.73 4291.630 0.068 0.880 0.97C > 11.71 0.041 0.548 0.605 12.26 O.O2O 0.297 0.331 II. 12 0.022 0-333 0.365 12.33 4294.936 0.072 0.931 1.021 12-33 0.044 0.589 0.640 12.97 0.018 0.268 0.302 10.15 O.OlS 0.269 0-30; 10.18 * Measured by A. on G. 4O AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907 Continued. Plate w 56. 1907, Feb. 15, 6 h s m G. M. T. Measured by L. on T. Distance from Limb 3.4 mm. Quality, good. p-f JT n seci) O 325.9 19.4 20.5 69.S 19.9 1.064 O-Q 251.5 35-4 36.0 54-0 11.7 i. 02 1 P 17-5 Si-4 51-7 38-3 8.8 I.OI2 D -6.9 67-4 67.6 22.4 7-4 1.008 Diameter 174.0 mm 82.4 82.5 I 7-5 6.9 1.007 Factor 1.041 *- f.S = 22?4 0= 38!3 X A t> . + ,, i A D . + + A V . + ., 1 km km o km km km km 4196.699 0.141 1.871 2.012 14.41 0.127 1.691 1.825 14.01 0.098 1-307 1.422 12.86 4197-257 0.142 1.883 2.024 14.49 0.128 1.701 1-835 14.08 0.098 I-307 1.422 12.86 4203.730 0.143 1.892 2-033 14.56 0.131 1-734 1.868 14-33 0.102 1-350 I-465 13-25 4209.144 0.143 1.889 2.030 14-54 0.131 1.732 1.866 14-32 O.IOI 1-337 1.452 13.14 4216.136 0.142 1.872 2.013 14.41 0.128 1.790 1.824 14.00 O.IOO 1-324 1-439 13.02 4220.509 0.143 1.881 2.O22 14.48 0.132 1.732 1.866 14.32 0.103 1-359 1-474 13-34 4232.887 0.143 1.858 1.999 14-31 0.132 1-730 1.864 14.30 O.IO2 1.341 1.456 13-17 4257.815 0.147 1.907 2.048 14.67 0.135 1-749 1.883 14-45 O.I 06 1-374 1.489 13-47 4258.477 0.145 1.881 2.O22 14.48 0.132 1.709 1.843 14.14 O.I02 1.329 1.444 13-07 4265.418 0.144 1.862 2.003 14-34 0.133 1.721 1-855 14.23 0.103 1-335 1-450 13.12 4266.081 0.146 1.888 2.O29 14-53 0.135 1.746 i. 880 14-43 o.i 06 1-372 1.487 13-45 4268.915 0.147 1.898 2.039 14.60 0.132 I-703 1-837 14.10 0.104 I-346 1.461 13.22 4276.836 0.145 1.868 2.OO9 14-39 0.134 1.727 i. 86 1 14.28 0.104 J-345 1.460 13.21 4284.838 0.146 1.874 2.015 M-43 0.133 1.709 1-843 14.14 0.103 1.329 1-444 13-07 4287.566 0.146 1-873 2.014 14-42 0.133 1.708 1.842 I4-I3 0.104 1.340 1-455 13.16 4288.310 0.144 1.848 1.989 14.24 0.133 1.707 1.841 I4-I3 0.104 1-339 1-454 13.16 4290.377 O.I4S 1.858 1-999 14-31 0-133 1.706 1.840 14.12 0.104 1.338 1-453 I3-I5 4290.542 0.145 1.858 1.999 14-31 0.134 1.717 1.851 14.20 0.105 1-349 1.464 13-25 4291.630 0.144 1.844 1.985 14.21 0.133 1.704 1.838 14.10 0.103 I-325 1.440 13-03 4294.936 0.146 1.868 2.009 14-39 0.134 1.716 1.850 14.20 0.104 I-336 I-45I 13.13 o = 54.0 = 69!S 4196.699 0.067 0.910 .000 12.08 0.038 0-533 0.586 11.88 4197-257 0.069 0.932 .022 12.34 0.038 0-533 0.586 11.88 4203.730 0.072 0.969 059 12.79 0.042 0.587 0.640 12.97 4209.144 0.072 0.966 056 12.75 0.042 0.586 0.639 12.95 4216.136 0.068 0.909 0.999 12.07 0.038 0-530 0.583 11.82 4220.509 0.071 0.951 .041 12.57 0.042 0.582 0.635 12.87 4232.887 0.072 0-959 049 12.67 0.041 o.547 0.600 12.16 4257-815 0.074 0.971 .061 12.82 0.043 0.588 0.641 12.99 4258.477 0.072 0.947 037 12.53 0.041 0.544 0-597 12. IO 4265.418 0.072 0.945 035 12.50 0.042 0-573 0.626 12.69 4266.081 0.074 0.969 059 12.79 0.044 0.600 0.653 13.24 4268.915 0.072 0.944 034 12.49 0.040 0.542 0-595 12. 06 4276.836 0.073 0.956 .046 12.63 0.042 0.568 0.621 12-59 4284.838 0.072 0-943 033 12.48 0.041 0-555 0.608 12-33 4287.566 0.074 0.964 054 12.73 0.041 0-554 0.607 12.31 4288.310 0.073 0-953 043 12.60 0.041 0-554 0.607 12.31 4290.377 0.071 0.919 .009 12.19 0.041 0-554 0.607 12.31 4290.542 0.073 0.952 .042 12.58 0.041 0-553 0.606 12.28 4291.630 0.074 0.963 053 12.72 0.043 0.580 0-633 12.83 4294.936 0.076 0.986 .076 13.00 0.041 0-533 0.586 11.88 RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907. TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS or 1906-1907 Continued. Plate 01 60. 1907, Feb. 28, 7 h is m G. M. T. Measured by L. on T. Distance from Limb 3.0 mm. Quality, good. P-P sect; 0-0 f D 339-1 264.7 21.4 -7-2 Diameter 173.2 mm Factor 1.036 38.9 39-5 50-5 11.4 .020 45-9 46-3 43-7 IO.O .015 54-7 55-o 35-0 8.8 .OI2 6i. 7 61.9 28.1 8.2 .010 69-4 69.6 20.4 7-7 .009 83-4 83-5 6.5 7-4 .008 = b5 = 6ts t> = 204 A V + , i A + , 1 A D + Jlj km km km km km km o 4196.699 0.144 1.904 2.044 14.60 0.143 1.892 2.032 14-52 0.128 1.697 1.830 13-86 4197-257 0.144 1.904 2.044 14.60 0.144 1.804 2.044 14.60 0.130 1.717 1.850 14.01 4203.730 0.146 1.927 2.067 14.78 0.146 1.928 2.068 14.78 0.130 1.716 1.849 14.00 4209.144 0.147 1.936 2.076 14-83 0.145 1.909 2.049 14.64 0.131 1.725 1.858 14.07 4216.136 0.146 1.918 2.058 14.71 0.146 I-93I 2.071 14.79 0.129 1.697 1.830 13-86 4220.509 0.146 I-9I5 2-055 14.68 0.146 1.929 2.069 14.78 0.131 1.719 1.852 14-03 4232.887 0.147 1.919 2.059 14.71 0.148 1.932 2.072 14.80 0.132 1.724 I-857 14.06 4257.815 0.150 1.940 2.080 14.86 0.151 I-95I 2.091 14.94 0-133 1.721 1.854 14.04 4258.477 0.148 1.908 2.048 14.63 0.147 1.901 2.041 14-58 0.132 1.708 1.841 13-94 4265.418 0.147 1.895 2-035 14-54 0.148 1.908 2.048 14.63 0.131 1.691 1.824 13.82 4266.081 0.147 1.895 2-035 14-54 0.150 1-933 2-073 14.81 0-135 1-744 1.877 14.22 4268.915 0.148 1.905 2.045 14.61 0.149 1.912 2.052 14.66 0.133 1.714 1.847 13-99 4276.836 0.146 1-873 2.013 14.38 0.149 1.912 2.052 14.66 0.132 1.696 1.829 13-85 4284.838 0.149 1.907 2.047 14.63 0.146 1.868 2.008 14-35 0.134 1.717 1.850 14.01 4287.566 0.149 1.906 2.046 14.62 0.149 1.906 2.046 14.62 0.131 1.678 1.811 13-71 4288.310 0.149 1.905 2-045 14.61 0.147 1.869 2.009 14-35 0.132 1.690 1.823 13.80 4290.377 0.147 1.877 2.017 14.41 0.146 1.865 2.005 14.32 0.134 1-703 1.836 13-90 4290.542 0.147 1.877 2.017 14.41 0.149 1.903 2-043 14-59 0.132 1.689 1.822 13.80 4291.630 0.146 1.864 2.004 14-32 0.148 1.887 2.027 14.48 0.133 1.700 I-833 13.88 4294.936 0.148 1.887 2.027 14.48 0.148 1.887 2.027 14.48 0.134 1.710 1.843 13.96 = 28tl = 35to = 43?7 = s!s A i) v + v 1 t A V v + i>i { A r + ! 1 A J + I, km km km km km km km km o 4196.699 0.114 1.510 1.636 I3-I7 0.104 1.380 1-497 12.97 0.086 1.144 .245 12.24 0.073 0-977 I.o6f 11.92 4197-257 0.114 1.510 1.636 I3-I7 0.104 1.380 1.497 12.97 0.087 1.158 .261 12.38 0.074 0.989 i.oSc 12.05 4203.730 0.118 1.562 1.67? I3-50 0.106 1.401 I.SiS 13.16 0.088 I.I68 .271 12.48 0.075 i. 002 1.091 12. 2O 4209.144 0.118 J-557 1.683 13-55 0.106 .400 I-5I7 13-15 0.089 1.182 .285 12.62 0.075 1. 000 1.091 12. l8 4216.136 0.114 1.501 I.62/ 13.09 0.105 384 1.501 13.01 0.087 1.152 255 12.32 0.074 0.985 1.076 12.01 4220.509 O.I 20 1-572 1.69? I3-67 0.107 .406 I-523 13.20 0.089 1. 174 277 12.54 0.077 1. 02 1 1. 112 12.41 4232.887 O.I 2O i-57o 1.696 I3-65 0.107 .401 1-518 13.16 0.090 1.182 .285 12.62 0.076 1.004 1.095 12.22 4257.815 O.I22 1.580 1.706 '3-73 o. 109 -413 53 13-26 0-093 I.2IO 313 12.89 0.078 1.020 I. Ill I2.4O 4258.477 O.I2I 1-563 1.685 13-59 0.108 397 5M 13.12 0.092 I-I93 297 12.74 0.077 1.008 1.099 12.27 4265.418 O.I 2O 1-55 1.676 13-49 0.108 396 .513 13-" 0.092 I.I92 295 12.72 0.076 0-993 1.084 12. IO 4266.081 0.123 1.582 1.708 13-75 0.109 409 .526 13-23 0.094 I.22O 323 12.99 0.079 1.029 1. 120 12.50 4268.915 0.120 1.548 I-674 13-47 0.108 395 5" 13.10 0.092 1.189 .292 12.69 0.077 I.OO4 1.095 12.22 4276.836 O.I22 1.568 1.694 I3-63 O.I 10 4i5 532 13.28 0.091 I.I76 -279 12.56 0.076 0.989 I.OSO 12.05 4284.838 O.I2I 1-552 1.678 I3-50 0.108 .387 1-504 13.04 0.093 I.I97 .300 12.77 0.078 1. 01 1 I.IO2 12.30 4287.566 0.122 1.566 1.694 13-63 0.108 1-387 1.504 13-04 0.092 1.186 .289 12.66 0.076 0.985 I.O76 12.01 4288.310 O.I2I 1-552 1.678 I3-50 0.109 1.398 I-5I5 13-13 0.092 1.185 1.288 12.65 0.078 1.009 I.IOO 12.28 4290.377 O.I22 1.564 1.690 13.60 0.108 1-385 1.502 13.02 0.092 1.184 1.287 12.64 0.075 0.972 1. 06.5 11.86 4290.542 O.I2I 1-55 1.676 13-49 0.109 1-397 1-514 13.12 0.092 1.182 1.285 12.62 0.077 0.996 I.OS? 12.13 4291.630 O.I22 1.560 1.686 13-57 0.108 1.384 1-501 13.01 0.093 i-i93 1.296 12.73 0.078 1.008 1.099 12.27 4294.936 0.122 1-559 1.685 I3-S6 0.108 1-383 1.500 13.00 0.092 1.181 1.284 1 2.6 1 0.078 1.007 1.098 12.26 42 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907 Continued. Plate w 61. 1907, Feb. 28, 7 h 4O m G. M. T. Measured by L. on T. Distance from Limb 3.1 mm. Quality, good. P-P sec 17 o 339-1 23-7 24.7 65-3 I7-S 1.049 o-n 264.7 29.7 30.S 59-5 M-3 1.032 p 21.4 38-9 39-S 5-5 11.4 1. 020 D -7.2 45-9 46.3 43-7 IO.O 1.016 Diameter 173.2 mm Factor i-37 p i = 43t7 *- S o!5 *- S9S *- 59: 5 A V + ., 1 A V V + Pj A I) + ! 1 A V , + ,, km km km km km km km km O 4107 2^7 *T A y / **o / 4203.730 0.086 1. 144 .247 12.25 0.076 1.015 1.106 12.34 0.054 0.730 0.801 II. 20 0.056 0-757 0.828 ".58 4209.144 0.088 1.148 251 12.28 0.077 1.026 1.117 12.47 0.058 0.781 0.852 11.92 0.055 0.742 0.813 "37 4216.136 0.085 1.127 .230 12.08 0.073 0.971 1.062 11.85 0.054 0.728 0.799 11.18 0-053 0-7I3 0.784 10.97 4220.509 0.086 I-I39 .242 12.20 0.076 1.009 I.IOO 12.28 0.058 0.779 0.850 11.89 0-055 0-739 O.SlO "33 4232.887 0.088 1.158 .261 12.38 0.076 1.004 1.095 12.22 0.056 0.752 0.823 11.51 0.056 0-749 0.820 11.47 4257.815 0.090 1.174 .277 12.54 0.079 1-034 125 12.56 0.060 0.803 0.874 12.22 0.060 0.794 0.865 12. IO 4258.477 0.089 I.I57 1.260 12.37 0.079 1-033 .124 12.55 0.057 0-754 0.825 "54 0.058 0.765 0.836 11.69 0.077 1. 001 .006 12.23 0.058 0.768 0.839 11.74 0.060 0.791 0.862 I 2. 06 4266 081 0.092 1.196 1.309 12.85 WJ :? .121 12.11 0.060 O.702 0.86-? 12.07 4268.015 0.078 1.015 .106 * * * 12.34 0.059 v. / y * 0.778 " W "O 0.849 11.88 0.060 0.791 0.862 I 2. 06 4276.836 0.096 1.163 1.266 12.43 0.078 1.013 .IO4 12.32 0.057 0.749 0.820 11.47 0.058 0.761 0.832 II.&4 4284.838 0.096 1.161 1.264 12.41 0.079 1.024 "5 12.44 0.058 O.760 0-831 11.62 0.058 0.760 0.831 11.62 4287.566 0.092 1.186 1.289 12.66 0.079 1.023 .114 12.43 0.057 0.746 0.817 "43 0.058 0.760 0.831 11.62 4288.310 0.091 I-I75 1.278 12.55 0.079 1.022 "3 12.42 0.060 0.785 0.856 11.97 0.059 0-773 0.844 II.80 4290.377 0.091 I-I73 1.276 12.53 0.077 0-995 .086 12.12 0.059 0.772 0.843 11.79 0.059 0-773 0.844 II.SO 4290.542 0.090 I-I59 1.262 12.39 0.080 1.034 -125 12.56 0.058 0.760 0.831 11.62 0.060 0.784 0.855 11.96 4291.630 0.091 1.172 1-275 12.52 0.078 1.008 .099 12.2? 0.058 0.758 0.829 1 1. 60 0.060 0.784 0.855 11.96 4294.936 0.090 I-I57 1.260 12.37 0.077 0-994 .085 12. II 0.059 0.771 0.842 11.78 0.058 0.758 0.829 1 1. 60 *- 65^3 ,- as:3 = *,' *- *' A 1 06 6oO t^L \J\t.\J\J\f 4.IO7 2S7 f-y / * j / 4203.730 0.044 0.605 0.664 11.28 0.045 0.618 0.677 11.50 0.046 0.633 0.692 "75 0.047 0.652 0.711 I 2. 08 4209.144 0.045 0.617 0.676 11.49 0.045 0.617 0.676 11.49 0.047 0.676 0-735 12.49 0.047 0.640 0.699 11.88 4216.136 0-043 0.587 0.646 10.98 0.043 0.587 0.646 10.98 0.048 0.652 0.711 12.08 0.045 0.621 0.68o "55 4220.509 0.044 0.602 0.661 11.23 0.044 0.600 0.659 11.19 0.047 0.645 0.704 11.96 0.047 0.642 O.7OI 11.91 4232.887 0.045 0.611 0.670 "38 0.047 0.638 0.697 11.84 0.050 0.669 0.728 12.37 0.049 0.669 0.728 12.37 4257-815 0.048 0.646 0.705 11.98 0.048 0.646 0.705 11.98 0.049 0.659 0.718 12. 2O 0.045 0.636 0-695 11.81 4258.47? 0.046 0.619 0.678 11.52 0.047 0.631 0.690 11.72 0.051 0.684 0-743 12.62 0.050 0.673 0.732 12.44 4265.418 0.046 0.618 0.677 11.50 0.045 0.604 0.663 11.26 0.047 0.629 0.688 11.69 0.051 0.685 0-744 12.64 4266.081 0.048 0.644 0.703 11.94 0.048 0.643 0.702 11.93 0.051 0.687 0.746 12.67 0.048 0.645 0.704 11.96 4268.915 0.048 0.643 0.702 11.93 0.052 0.698 0-757 12.86 0.054 0.719 0.778 13.22 4276.836 0.045 0.602 0.661 11.23 0.046 0.615 0.674 "-45 0.05 T 0.680 0-739 12.56 0.050 0.672 0.731 12.42 4284.838 0.046 0.614 0.673 "43 0.047 0.626 0.685 11.64 0.052 ^694 0-753 12.79 0-053 0.712 0.771 13.10 4287.566 0.047 0.625 0.684 11.62 0.047 0.625 0.684 11.62 0.049 0.656 0-715 12.15 0.052 0.687 0.746 12.67 4288.310 0.047 0.625 0.684 11.62 0.047 0.626 0.685 11.64 O.O49 0-653 0.712 12. IO 0.049 0.656 0.7IS 12.15 4290.377 0.048 0.638 0.697 11.84 0.047 0.625 0.684 11.62 O.048 0.645 0.704 11.96 0.051 0.682 0.741 12.59 4290.542 0.045 0.598 0.657 ii. 16 0.046 0.612 0.671 11.40 0.049 0.650 0.709 I2.O5 0.049 0.650 0.709 12.05 4291.630 0.047 0.624 0.683 1 1. 60 0.046 0.611 0.670 ".38 O.O52 0.697 0.756 12.84 0.049 0.650 0.709 12.05 4294.936 0.048 0.637 0.696 11.82 0.046 0.610 0.669 "37 0.050 0.668 0.727 I2 -35 0.048 0.639 0.698 11.86 * Measured by A. on G. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907. 43 TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS or 1906-1907 Continued. Plate to 62. 1907, Feb. 28, g h 15 G. M. T. Measured by L. on T. Distance from Limb 3.1 mm. Quality, good. seci) O 339-1 o-n 264.7 p 21.4 D -7.2 Diameter 173.2 mm Factor 1.037 51. 5 5J-9 38.1 9-2 1.013 59-5 59-8 30.2 8.4 i. on 67-3 67-S 22.5 7-8 1.009 74-3 74-4 15-6 7-5 i.oog 82.0 82.1 7-9 7-3 1.008 96.0 96.0 -6.0 7-3 1.008 = 6to = ?!o = i$'6 A V r + , J A V + ! & A V + , 1 km km km km km km 4196.699 0.144 1.905 2.045 14.60 0.138 1.831 I.Q7I 14.13 0.138 1.829 1.965 14.48 4I97-257 0.144 I.905 2.045 14.60 0.139 1.842 1.982 14.21 0.139 1.840 1.976 14.57 4203.730 0.145 1.914 2.054 14.66 0.142 1. 880 2.O2O 14.48 0.142 1-875 2.01 1 1482 4209.144 0.146 1-923 2-063 14.72 0.142 1.877 2.017 14.46 0.142 1.872 2.008 1480 4216.136 0.144 1.891 2.031 14.50 0.141 1.854 1.994 14.29 0.141 I.854 1.990 I4'6? 4220.509 0.147 1.926 2.066 14.74 0.142 1.864 2.OO4 14.36 0.142 1.864 2.000 14-74 4232-887 0.148 I-93I 2.071 14.78 0.144 1.879 2.OI9 14.47 0.144 1.880 2.Ol6 14.86 4257.815 0.150 1.938 2.078 14.83 0.147 1.897 2.037 14.60 0.147 1.900 2.036 15.01 4258.47? 0.146 1.887 2.027 14.47 0.146 1.874 2.OI4 14.44 0.144 1.872 2.008 14.80 4265.418 0.147 1.895 2.035 14.52 0.144 1.869 2.OO9 14.40 0.144 1.867 2.003 14 76 4266.081 0.150 1-933 2.073 14.80 0.144 1.868 2.008 14-39 0.144 1.866 2.OO2 14.76 4268.915 0.147 i.88g 2.029 14.48 0.144 1.867 2.OO7 14-38 0.144 1.865 2.001 14-75 4276.836 0.147 1.887 2.027 14.47 0.145 1.864 2.OO4 14.36 0.145 1.862 1.998 14-73 4284.838 0.148 1.894 2-034 14-52 0.144 1.830 1.970 14.12 0.144 1.845 I.gSl 14.60 4287.566 0.146 1.868 2.008 14-33 0.143 1.825 1.965 14.08 0.143 1.830 1.966 14.47 4288.310 0.150 1.917 2.057 14.68 0.144 1.844 1.984 14.22 0.144 1.842 1.978 14.58 4290.377 0.148 1.890 2.030 14.49 0.143 1.830 1.970 14.12 0.142 1.828 1.964 14.48 4290.542 0.148 1.890 2.030 14.49 0.144 1.842 1.982 14.21 0.144 1.840 1.976 14-57 4291.630 0.146 1.865 2-005 14-31 0.145 1.853 1-993 14.28 0.145 1.851 1.987 14.65 4294.936 0.148 1.887 2.027 14.47 0.145 1.859 1.999 14.33 0.145 1.857 1-993 14.69 = 2* = 30^2 = 38*1 4196.699 0.124 1.644 1-775 13.64 0.115 i-Si? 1.641 13.48 0.105 1.396 S09 13.61 4197-257 0.123 1.628 1-759 13-52 0.116 1.529 1-653 13.58 0.105 1.396 509 13.61 4203.730 0.126 1.664 J-795 13-79 0.118 1.548 1.672 13-73 0.107 I.4I5 -528 13-79 4209.144 0.127 1-673 1.804 13.86 0.118 1-547 1.671 13.73 0.107 I-4I3 -526 13-77 4216.136 0.125 1.645 1.776 13.65 0.116 1-527 1.651 13.55 0.106 1-399 512 13.64 4220.509 0.126 1-655 1.786 13-72 0.118 1-544 1.668 13.70 0.107 1.409 .522 13-73 4232.887 0.128 1.672 1.803 13.85 0.118 1-543 1.667 13.69 0.106 i-39' 504 13-57 4257-815 0.131 1.694 1.825 14.02 O.I 2O 1-554 1.678 13-78 O.IIO 1.428 541 13.90 4258.477 0.130 1.681 1. 812 13-92 0.119 I-54I 1-665 13-68 0.108 1.402 5iS 13-67 4265.418 0.128 1.650 1.781 13.69 0.118 1.521 1.645 13.51 0.108 1.400 I-SI3 13-65 4266.081 0.130 1.676 1.807 13.89 O.I 2O 1-549 1-673 13.74 O.IIO 1.424 1-537 13-87 4268.915 0.130 1-675 i. 806 13-88 0.118 1-518 1.642 13.49 0.108 1.389 1.502 13-55 4276.836 0.129 1.656 1.787 I3-7V 0.118 1-518 1.642 13.49 0.108 1.389 .502 13-55 4284.838 0.131 1.678 1.809 i .90 0.116 1.490 1.614 13.26 0.107 1-378 .491 13-45 4287.566 0.130 1.662 1-793 13-78 0.117 1.501 1.625 13.35 0.108 1-388 .501 13-54 4288.310 0.129 1.649 1.780 13-68 0.122 1.560 1.684 13.83 0.108 1.388 .501 13-54 4290.377 0.130 i. 660 1.791 I3-76 O.II8 1.511 1-635 13-43 0.107 1-375 .488 I3-42 4290.542 0.127 1.623 J-754 13-48 O.I 2O 1-535 1.659 13-63 0.108 1-387 .500 13-53 4291.630 0.128 1-634 1-765 I3-S6 O.I 20 1-534 1-658 13.62 0.109 1-397 .510 13.62 4294.936 0.128 1-633 1.764 13-56 O.I 2O 1-533 1-657 13.61 O.IIO 1.409 .522 '3.73 44 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907 -Continued. Plate w 63. 1907, Feb. 28, 9 h 45" G. M. T. Measured by L. on T. Distance from Limb 3.1 mm. Quality, good. t-P secy Q 339.1 45-8 46.2 43-8 IO.O 1.016 O-n 264.7 38.8 39-3 S-7 "5 i. 02 1 p 21.4 54-6 54-9 3S-I 8.8 I.OI2 D -7.2 61.6 61.8 28.2 8.2 I.OIO Diameter 173.2 mm 69-3 69.4 20.6 7-7 1.009 Factor 1.037 82.8 82.8 7.2 7-3 1.008 = ?:* = 2O?6 = aSta X A V v + v l e A " + fj e A r + , { km km km km km km . 4196.699 0.143 i-95 2.045 14-63 0.126 1.668 1.801 13.66 0.114 .510 1.636 13.18 4197-257 0.144 1.918 2.058 14-73 0.128 1.694 1.827 13.86 0.116 536 1.662 13.39 4203.730 0.147 953 2.093 14.98 O.I 2O 1. 600 1-733 13.14 0.118 .560 1.686 13.58 4209.144 0.142 .885 2.025 14.49 0.129 1.700 1-833 13.90 o.i 19 570 1.696 13.66 4216.136 0.144 95 2.045 14.63 0.130 1.708 1.841 13.96 0.118 553 1.679 13.53 4220.509 0.144 .902 2.042 14.61 0.132 730 1-863 14.13 O.I 2O 575 1.701 13.70 4232.887 0.146 .920 2.060 14.74 0.133 .736 1.869 14.18 O.I 2O 569 1-695 13-65 4257-815 0.150 953 2.093 14.98 0.133 .719 1.852 14.05 O.I 2O 555 i. 68 1 13.54 4258.477 0.148 .927 2.067 14.79 0-133 .719 1.852 14.05 0.118 526 1.652 13-31 4265.418 0.147 .896 2.036 14.57 0.132 .702 1.835 13.92 0.118 524 1.650 13.29 4266.081 0.150 947 2.087 14-93 0-133 715 1.848 14.02 0.124 .602 1.728 13.92 4268.915 0.146 .894 2.034 14.55 0.134 .725 1.858 14.09 0.120 545 1.671 13.46 4276.836 0.147 .901 2.041 14.61 0-133 1.708 1.841 13.96 O.I 2O 542 1.668 13.44 4284.838 0.149 .921 2.001 14-75 0.134 1.716 1.849 14.02 0.123 579 1-705 13.73 4287.566 0.148 .906 2.046 14.64 0.136 1.738 1.871 14.19 O.I2I 549 1-675 13.49 4288.310 0.146 .881 2.O2I 14.46 0.134 I.7I3 1.846 14.00 0.124 .588 1.714 13.81 4290.377 0.147 .892 2.032 14-54 0.134 1.712 1.845 13.99 O.IlS .510 1.636 13.18 4290.542 0.148 93 2.043 14.62 0.135 1.724 1.857 14.08 O.I 2O 1-535 1.661 13.38 4291.630 0.148 1.902 2.O42 14.61 0.134 1.7X1 1.844 13.99 0.119 1.522 1.648 13.28 4294.936 0.148 1.901 2.O4I 14.61 0.132 1.685 1.818 13.79 0.118 1.508 1.634 13.16 = 35!i = sot? = 43: 4196.699 0.105 1.396 513 13-13 0.068 0.912 1.002 11.23 0.086 1.150 1.254 12.33 4197.257 o.i 06 1.409 .526 13-25 0.069 0.924 I.OI4 11.36 0.088 1.174 1.278 12.57 4203.730 0.108 i-43i 548 13-44 0.072 0.962 1.052 11.79 0.090 199 303 12.82 4209.144 0.108 1.428 545 13.40 0.071 0.948 1.038 11.63 0.089 .181 .285 12.64 4216.136 o.i 06 1-399 .516 13.16 0.071 0.945 035 1 1. 60 0.087 152 .256 12.35 4220.509 O.IIO 1-447 .564 13-57 0.073 0.971 .061 11.89 0.090 .188 .292 12.71 4232.887 0.108 1.412 529 13-27 0.071 0-939 .029 "53 0.090 .183 .287 12.66 4257.815 O.I II 1.440 557 13-51 0.076 O.Q95 .085 12.16 0.094 .224 .328 13.06 4258.477 0.108 1-399 .516 13.16 0.075 0.982 .072 12. 02 0.090 .172 .276 12.55 4265.418 0.107 1-385 1.502 13-03 0.075 0.982 .072 I 2. 02 0.089 157 .261 12.40 4266.081 O.II2 1.449 1.566 13-59 0-075 0.984 .074 I2.O4 0.092 .194 .298 12.77 4268.915 O.IIO 1.422 1-539 13-36 0.076 0.989 .079 12.09 0.091 .180 .284 12.63 4276.836 0.108 1-394 1.511 13.11 0.076 0.988 .078 I 2.08 0.090 .165 .269 12.48 4284.838 O.IIO I.4I5 1-532 13.29 0.078 I.OI2 .IO2 12-35 0.092 .186 .290 12.69 4287.566 O.IIO I-4I3 1-53 13.28 0.074 0-959 .049 11.76 0.092 .185 1.289 12.68 4288.310 O.I 12 1-437 1-554 13.48 0.074 0.958 .048 "75 0.090 .160 1.264 12.43 4290.377 0.108 1-387 1.504 13-05 0.076 0.983 073 12.03 0.091 .171 1-275 12.54 4290.542 O.III 1.424 I-54I 13-37 0.074 9-957 047 11.74 0.093 .196 1.300 12.79 4291.630 O.I 1 2 1-435 1-552 13-47 0.076 0.982 .072 12.02 0.092 .182 1.286 12.65 4294.936 O.II2 1-434 I-55I 13-46 0.077 0-995 .085 12. l6 0.092 .182 1.286 12.65 RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907. TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907 Continued. Plate o> 55. 1907, Feb. 15, s h 40'" G. M. T. Measured by L. on T. Distance from Limb 3.4 mm. Quality, good. p P T (j> i) seci; 45 G 325.9 O-fi 251.5 P 17.5 Si-4 67.4 82.4 Si-7 67.6 82.5 38.3 22.4 7-5 8.8 7-4 6.9 I.OI2 1.008 1.007 D -6.9 Diameter 174.0 mm Factor 1.041 X = 7.S = ?4 * = 3&.3 A fl + "l A V + ! A V + ! { km km O km km km km 9 4196.699 0.142 1.884 2.025 14.50 0.129 1.711 1.845 14.16 0.098 1.304 1.419 12.84 4197-257 0.142 1.884 2.025 14-50 0.129 1.711 1-845 14.16 0.097 1.292 1.407 12.73 4203.730 0.146 1.924 2.065 14.79 0.130 1.721 1-855 14-23 0.102 1-354 1.469 13.29 4209.144 0.147 1.936 2.077 14.87 0.131 1-730 1.864 14-30 0.103 1.364 1-479 I3-38 4216.136 0-145 1.910 2.051 14.69 0.129 1.699 1.833 14.07 0.099 I-3I4 1.429 12.93 4220.509 0.146 1.918 2.059 14-74 0.131 I-723 1-857 14-25 0.103 1.361 1.476 13-35 4232.887 0.147 1.924 2.065 M-79 0.132 1.728 1.862 14.28 0.104 1.368 1.483 I3-42 4257-815 0.149 1.923 2.064 14.78 0.135 1.741 1-875 14-39 0.106 1-378 1-493 I3-5I 4258.477 0.146 1.898 2.039 14.60 0.131 1.696 1.830 14.04 0.105 '365 1.480 13-39 4265.418 0.148 1.919 2.060 14-75 0.131 1.695 1.829 14-03 0.104 J-352 1.467 I3-27 4266.081 0.151 1-953 2.094 14.99 0.135 1.738 1.872 14-37 0.108 1-395 1.510 13.66 4268.915 0.149 1.918 2.059 14.74 0.134 I-725 1.859 14.27 0.104 1-347 1.462 I3-23 4276.836 0.148 1.903 2.044 14.64 0.132 1.700 1.834 14.07 0.103 1-334 1.449 13.11 4284.838 0.149 i-9i3 2-054 14.71 0.134 1.722 1.856 14.24 0.104 1-342 1-457 13-18 4287.566 0.147 1.885 2.026 I4-5I 0.133 1.709 1-843 14.14 0.104 i-34i I-456 I3-I7 4288.310 0.149 1.910 2.051 14.69 0.133 1.708 1.842 14-13 0.106 1-365 1.480 13-39 4290-377 0.146 1.871 2.OI2 14.41 0.133 1.707 1.841 14-13 0.105 1-352 1.467 I3-27 4290.542 0.148 1.896 2.037 14-59 0.134 I-7I5 1.849 14-19 O.IO2 I.3IS 1.430 12.94 4291.630 0.148 1.895 2.036 14.58 0-134 1.714 1.848 14.18 0.105 1-350 1.465 13.25 4294.936 0.148 1.894 2.035 14-57 0.131 1.678 1.812 13.90 0.108 1-387 1.502 13-59 Plates <> 64, w 67, w 68, and a 69. 1907, April 7, w 64, 3 h 2o m ; u 67, 5 h 45 m ; w 68, 6 h 45 ; w 69, 7 h io m . G. M. T. Measured by L. on T. Distance from Limb 2.3 mm. Quality, good. w 64,167 u 68, 69 O 0-0 i6? 7 302.3 i6?8 302.4 p D 26.5 -6.1 p-p O 10.9 77S *) 29-5 seci 1.149 Diameter 171.7 mm Factor 1.027 X u 64, = 77?s w 67, = 77?s <> 68, 9, = 7?!s A t> V + "] A V -f- j A f + , i A V + ! f km km . km km km km km km 4196.699 O.O2O 0.298 0-333 10.92 0.018 0.269 0-304 9-97 0.018 0.269 0-304 9-97 O.O2O 0.298 0-333 10.92 4197-257 0.022 0-304 0-339 II. 12 0.020 0.298 0-333 10.92 O.O2O 0.298 0-333 10.92 O.O2O 0.298 0-333 10.92 4203.730 0.023 0.342 0-377 12-37 O.O22 0.327 0.362 11.87 0.022 0.328 0.363 11.91 0.022 0.328 0-363 11.91 4209.144 O.O22 0-303 0-338 II.O9 O.O22 0.327 0.362 11.87 O.O22 0-328 0.363 11.91 O.O2I 0.312 0-347 11.38 4216.136 0.020 0-295 0-330 10.82 O.OI9 0.282 0.317 10.40 O.OI9 0.282 0.317 10.40 O.O2O 0.296 0-33' 10.86 4220.509 O.O22 0.324 0-359 11.78 O.O22 0.325 0.360 11.81 O.O22 0.326 0.361 11.84 0.024 0-355 0-390 12.79 4232.887 O.O22 0.324 0-359 11.78 O.O22 0.324 0-359 11.78 O.O22 0-323 0.358 11.74 O.O24 0-351 0.386 12.66 4257-815 0.024 0-349 0.384 I 2.6O 0.026 0.380 0-415 13-61 O.O26 0-380 0-415 13.61 0.028 0.408 0-443 14-53 4258.477 O.O24 0-349 0.384 I 2. 60 O.022 0.323 0.358 11.74 O.024 0-349 0.384 12.60 O.O24 0-349 0.384 12.60 4265.418 O.O24 0.349 0.384 1 2. 60 0.023 0-335 0.370 12.14 O.O22 0.322 0-357 11.71 O.O22 0-320 0-355 11.64 4266.081 0.025 0-363 0-398 13.06 0.026 0-379 0.414 I3-58 0.025 0.363 0.398 13.06 O.O24 0-349 0.384 12.60 4268.915 0.023 0-334 0.369 12. IO O.O24 0-347 0.382 12-53 0.023 0-334 0-369 12.10 O.O22 0.320 0.355 11.64 4276.836 O.O22 0.319 0-354 II.6l O.O24 0-347 0.382 12-53 O.O24 0.348 0-383 12.56 O.O24 0.348 0-383 12.56 4284.838 O.O22 0.319 0-354 11.61 O.O24 0-347 0.382 12-53 O.024 0.348 0.383 12.56 O.O22 0.320 0-355 11.64 4287.566 O.O2I 0-303 0-338 11.09 0.025 0.361 0.396 12-99 O.O22 0.317 0-352 "55 O.O24 0-347 0.382 12.53 4288.310 O.O22 0.318 0-353 11.58 O.O24 0-347 0.382 12.53 0.023 0.332 0.367 12.04 O.O24 0-347 0-382 12.53 4290.377 0.025 0.361 0.396 12.99 O.O22 0.3I7 0.352 ii-SS 0.024 0-347 0.382 12-53 O.022 0.319 0-354 11.61 4290.542 0.023 0.332 0.367 12.04 0.023 0.332 0.367 12.04 O.O26 0-374 0.409 13-42 O.O24 0.346 0.381 12.50 4291.630 0.025 0.360 0-395 12.96 O.O28 0.404 0-439 14.40 O.O25 0.360 0-395 12.96 O.O24 0.346 0.381 12.50 4294.936 O.O22 0.317 0.352 ii-SS 0.024 0.346 0.381 12.50 0.024 0.346 0.381 12.50 0.023 0-332 0.367 12.04 46 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907 Continued. Plate u> 81. 1907, April 22, 8 h 2o m G. M. T. = 79!$, measured by A. on T. = 67^2 and 72$ measured by L. on T. Distance from Limb i.i mm. Quality, good. P-P sec i? 3I.S G-0 317.1 P 25.7 D -4.9 Diameter 169.3 mm Factor 1.013 9.3 10.5 79.5 28.1 1.134 16. 8 17.5 72.5 16.6 1.044 22.3 22.8 67.2 12.8 1.026 X , = 6* * = 6 7! , *-7* A V ' + ' 1 A t) '+'' 1 A V ' + '' i km km km km km km o 4196.699 0.042 0-553 0.617 11.30 0.041 0.541 0.605 11.08 0.032 0.429 0.480 "33 4197-257 0.042 0-553 0.617 11.30 0.042 0-553 0.617 11.30 0.033 0.441 0.492 11.62 4203.730 0-043 0.564 0.628 11.51 0.044 0-577 0.641 11.74 0.034 0-454 0.505 11.92 4209.144 0.045 0.588 0.652 "95 0.045 0.588 0.652 "95 0.034 0-453 0.504 11.90 4216.136 0.044 0-575 0.639 11.71 0.040 0-523 0.587 10.75 0.033 0-439 0.490 "57 4220.509 0.044 0.572 0.636 11.65 0.044 0-574 0.638 11.69 0.034 0.451 0.502 11.85 4232.887 0.046 0.596 0.66o 12.09 0.048 0.617 0.681 12.48 0.035 0-459 0.510 12.04 4257-815 0.049 0.628 0.692 12.68 0.048 0.615 0.679 12.44 0.036 0.470 0.521 12.30 4258.477 0.048 0.615 0.679 12.44 0.045 0-577 0.641 11.74 0.034 0-444 0-495 11.69 4265. 4 X 8 0.046 0.590 0.654 11.98 0.046 0.590 0.654 11.98 0.034 0.444 0-495 11.69 4266.081 0.050 0.638 0.702 12.86 0.048 0.613 0.677 12.40 0.037 0.482 0-533 12.58 4268.915 0.047 0.600 0.664 12. l6 0.046 0.587 0.651 "93 0.033 0.430 0.481 11.36 4276.836 0.048 0.613 0.677 12.40 0.045 0-575 0.639 11.71 0.036 0.465 0.516 12. 18 4284.838 0.044 0-559 0.623 11.41 0.047 0.598 0.662 12.13 0.034 0.440 0.591 "59 4287.566 0.048 0.610 0.674 12-35 0.048 0.611 0.675 12.37 0.036 0.465 0.516 12.18 4288.310 0.048 0.610 0-674 12-35 0.046 0.584 0.648 11.87 0.034 0.440 0.491 ii-S9 4290.377 0.047 0.598 0.662 12.13 0.045 0-573 0-637 11.67 0-035 0.452 0-503 u.88 4290.542 0.045 0.572 0.636 11.65 0.047 0-597 0.66 1 12. II 0.034 0-439 0.490 ii-57 4291.630 0.047 0-597 0.661 12. II 0.047 0-597 0.661 12.11 0.034 0-439 0.490 ii-57 4294.936 0.048 0.609 0.673 12-33 0.048 0.609 0.673 12.33 0.036 0.464 0.515 12. 16 *-rfS = 79.S = 79tS '4196.699 0.032 0.428 0.479 11.31 0.019 0.277 0.311 12.12 0.019 0.281 0-315 12.27 4I97-257 0.031 0.416 0.467 11.03 0.019 0.278 0.312 12.15 0.019 0.278 0.312 12.15 4203.730 0.034 0-454 0.505 11.92 0.020 0.282 0.316 12.31 O.O2O 0.293 0.327 12.74 4209.144 0.034 0-453 0.504 11.90 O.Oig 0.279 0-313 12.19 O.OI9 0.281 0-315 12.27 4216.136 0.032 0.425 0.476 11.24 O.OI9 0.280 0-314 12.23 0.020 0.281 0.315 12.27 4220.509 0.034 0-452 0.503 u.88 O.O2O 0.293 0.327 12.74 0.02O 0.282 0.316 12.31 4232-887 0.033 0.436 0-487 11.50 0.020 0.282 0.316 12.31 O.OI9 0.276 0.310 I 2. 08 4257-8I5 0.036 0.470 0.521 12.30 O.O2I 0-293 0.327 12-74 O.O2I 0.294 0.328 12.78 4258.477 0.034 0-443 0-494 11.66 O.O2I 0-293 0.327 12.74 0.020 0.286 0.320 12.47 4265.418 0.034 0-443 0.494 11.66 O.O20 0.279 0-313 12.19 O.O2O 0.276 0.310 I 2. 08 4266.081 0.036 0.470 0.521 12.30 0.020 0.284 0.318 12.39 O.O2O 0.284 0.318 12.39 4268.915 0.034 0.442 0-493 11.64 O.O2O 0.280 0.314 12.23 O.O2O 0.282 0.316 12.31 4276.836 0.034 0.441 0.492 11.62 O.O2O 0.282 0.316 12.31 0.020 0.278 0.312 12.15 4284.838 0.033 0.427 0.478 11.29 0.019 0.272 0.306 11.92 O.O2O 0.278 0.312 12.15 4287.566 0.034 0.440 0.491 "59 O.O2O 0.277 0.311 12.12 O.O2O 0.285 0.319 12.43 4288.310 0.035 0-453 0.504 11.90 O.OI9 0.272 0.306 11.92 0.020 0.279 0-313 12.19 4290.377 0.035 0.452 0.503 u.88 O.OI9 0.272 0.306 11.92 0.019 0.272 0.306 11.92 4290.542 0.036 0.464 0.515 12. l6 0.020 0.280 0.314 12.23 O.Oig 0.266 0.300 11.69 4291.630 0.035 0-453 0-504 11.90 O.O2O 0.282 0.316 12.31 0.02O 0.274 0.308 I2.OO 4294.936 0.036 0.464 0-515 12. l6 O.O2O 0.282 0.316 12.31 0.020 0.277 0.311 12.12 RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907. 47 TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OP 1906-1907 Continued. Plate a 83. 1907, May 10, io h 15"" G. M. T. Measured by A. on G. Distance from Limb i.i mm. Quality, good. 49.! 0-n -25.3 P 22.4 D -3.0 Diameter 168.2 mm Factor 1.013 io-4 io.8 79- 2 IO -7 15.4 15.6 74.4 11.6 26.4 26.5 63.5 6.9 seer; 1.044 1. 02 1 1.007 = 63!$ = fists = 74?4 . A r f + fj 1 A V S + JIj J A V v + v l km km km km O km km 4196.699 0.048 0.624 0.697 11.09 0.049 0.636 0.709 11.28 0.030 0-393 0-443 11.70 4197-257 0.050 0.651 0-724 11.52 0.048 0.623 0.696 11.07 0-030 0.388 0.438 11.56 4203.730 0.049 0.630 0.703 11.19 0.051 0.658 0-731 11.63 0.029 0.382 0-432 11.40 4209.144 0.049 0.628 0.701 11.15 0.052 0.665 0.738 11-74 0-030 0-386 0.436 11.51 4216.136 0.050 0-637 0.710 11.30 0.048 0.622 0.695 1 1. 06 0.030 0.390 0.440 11.62 4220.509 0.049 0.631 0.704 II. 21 0.052 0.667 0.740 11.77 0.029 0.380 0.430 n-35 4232.887 0.048 0.618 0.691 10.99 0-051 0.656 0.729 1 1. 60 0.030 0-393 0-443 11.69 4257.815 0.050 0.636 0.709 11.28 0-053 0.669 0.742 11.81 0.030 0.384 0-434 11.46 4258.477 0.050 0.634 0.707 11.25 0-052 0-655 0.728 11.58 0.030 0-379 0.429 11.32 4265.418 0.050 0.629 0.702 11.17 0.050 0-634 0.707 11.25 0.031 0.390 0.440 11.62 4266.081 0.050 0.627 0.700 11.14 0.050 0.627 0.700 11.14 0.032 0.409 0-459 12.12 4268.915 0.051 0.641 0.714 11.36 0-051 0.646 0.719 11.44 0.029 0.370 0.420 11.09 4276.836 0.049 0.612 0.685 10.90 0.054 0.677 0.750 11-93 0.029 0-371 0.421 II. 12 4284.838 0.049 0.610 0.683 10.87 0.051 0-635 0.708 11.26 0.030 0.380 0.430 "35 4287.566 0.049 0.617 0.690 10.98 0.050 0.629 0.702 11.17 0.031 0-394 0-444 11.72 4288.310 0.050 0.629 0.702 11.17 0.051 0.639 0.712 "33 0.031 0-394 0.444 11.72 4290.377 0.050 0.623 0.696 II.O7 0.052 0.650 0.723 11.50 0.028 0-354 0-434 11.46 4290.542 0.050 0.623 0.696 11.07 0.052 0.648 0.721 11.47 0.031 0-387 0-437 "54 4291.630 0.050 0.623 0.696 11.07 0-052 0-653 0.726 "55 0.030 0.384 0-434 11.46 4294.936 0.049 0.613 0.686 10.92 0.052 0.647 0.720 11.46 0.030 0-383 0-433 "43 = 74!4 = 7?!* = 79*2 4196.699 0.031 0.404 0-454 11.99 0.019 0.252 0-293 II. IO 0.019 0-255 0.296 II. 21 4197-257 0.032 0.424 0.474 12.51 0.019 0.257 0.298 11.29 0.018 0.247 0.288 10.91 4203.730 0.032 0.418 0.468 12.36 0.020 0.268 0.309 11.71 0.020 0-273 0.314 11.90 4209.144 0.032 0.418 0.468 12.36 O.O2O 0.267 0.308 11.67 O.O2O 0.270 0.311 11.78 4216.136 0.031 0.401 0.451 11.91 O.O2O 0.272 0.313 11.86 O.OI9 0.248 0.289 10.95 4220.509 0.033 0.429 0.479 12.65 O.O2O 0.260 0.301 11.40 0.020 0.271 0.312 11.82 4232.887 0.032 0.409 0-459 12.12 0.020 0.270 0.311 11.78 0.020 0.261 0.302 II-44 4257-815 0.034 0-435 0.485 12. 80 O.O2O 0.261 0-302 11.44 O.O2O 0.256 0.297 11.25 4258.477 0.034 0.430 0.480 12.67 O.OI9 0.251 0.292 1 1. 06 O.Oig 0.246 0.287 10.87 4265.418 0.034 0.432 0.482 12.72 0.020 0.267 0.308 11.67 0.020 0.256 0.297 11.25 4266.081 0.032 0.432 0.482 12.72 O.O2I 0-274 0.3IS n-93 O.O2O 0.261 0-302 11.44 4268.915 0.032 0.411 0.461 12.17 O.O2O 0.266 0.307 11.63 O.OI9 0.246 0.287 10.87 4276.836 0.032 0.404 0-454 11.98 0.020 0.262 0.303 11.48 0.020 0.264 0-305 11.56 4284.838 0.033 0.413 0.463 12.22 O.O2O 0.259 0.300 n-37 O.O2O 0.256 0.297 11.25 4287.566 0.032 0.405 0-455 12. OI O.O2I 0.269 0.310 "75 O.O2O 0-254 0-295 II. 18 4288.310 0.031 0.389 0-439 11-59 0.020 0.261 0.302 "44 0.020 0.261 0-302 11.44 4290.377 0032 0-395 0-445 11-75 O.OlS 0.233 0.274 10.38 O.O2O 0.258 0.299 "33 4290.542 0-033 0.412 0.462 12. 2O O.OI9 0.248 0.289 10.95 O.O2O 0.258 0.299 "33 4291.630 0.034 0.432 0.482 12.72 O.O2I 0.269 0.310 ii-75 0.020 0.258 0.299 "33 4294.936 0.032 0-399 0-449 11.85 0.020 0-253 0.294 11.14 O.O2I 0.273 0.314 11.90 | 48 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907 Continued. Plate w 85. 1907, May 30, I2 h s m G. M. T. Measured by A. on T. Distance from Limb i.o mm. Quality, good. P-P secy o 68.4 10. ,2 IO.2 79-8 4.2 1.003 O-fl -6.0 15 2 15-2 74-8 2.8 I.OOI p 16.3 26 ,2 26.2 63.8 1.7 I.OOO D -0.7 Diameter 167.9 mm Factor 1. 01 2 4- = 63$ = 6 3 !8 = 74!8 A t) r + , J A e + ! { A + ! km km km km . km km 4196.699 0.054 0.692 0.760 12.22 0-055 0.704 0.772 12.41 0.032 0.410 0.461 12.48 4197-257 0.054 0.692 0.760 12.22 0-055 0.704 0.772 12.41 0.032 0.410 0.461 12.48 4203.730 o-oSS 0.703 0.771 12.40 0.058 0.741 0.809 13.01 0.034 0-434 0-485 13-13 4209.144 0.058 0.740 0.808 12.99 0.056 0.714 0.782 12-57 0.034 0-433 0.484 13.11 4216.136 0.056 0.712 0.780 12-54 0-055 0.699 0.767 12.33 0.034 0.432 0.483 13.08 4220.509 0.056 0.711 0-779 12.52 0.058 Q-737 0.805 12.95 0.034 0.432 0.483 13.08 4232.887 0.058 0-734 0.802 I2.9O 0.058 o-734 0.802 12.90 0.033 0.419 0.470 12-73 4257-815 0.058 0.727 0-795 12.78 0.058 0.727 0-795 12.78 0-033 0.413 0.464 12.56 4258.477 0.056 0.702 0.770 12.38 0-057 0-713 0.781 12.56 0.034 0.426 0-477 12.92 4265.418 0.058 0-725 0-793 12.75 0.060 0.749 0.817 13-14 0-035 0.438 0.489 13-24 4266.081 0.058 0.724 0.792 12.74 0.058 0.724 0.792 12.73 0.036 0.450 0.501 13-57 4268.915 0-057 0.710 0.778 12.51 0.059 0.736 0.804 12.93 0.033 0.412 0.463 12.54 4276.836 0.059 0-734 0.802 12.90 0.060 0.736 0.804 12.93 0-033 0.410 0.461 12.48 4284.838 0.059 0.732 0.800 12.86 0.060 0-744 0.812 13.06 0-035 0-434 0.485 13-13 4287.566 0.057 0.706 0-774 12.45 0.059 0-731 0.799 12.85 0-035 0-433 0.484 13.10 4288.310 0.057 0.706 0-774 12.45 0.060 0-743 0.811 13-04 0.032 0.396 0.447 12. IO 4290.377 0.056 0.693 0.761 12.24 0.058 0.718 0.786 12.64 0-034 0.421 0.472 12.78 4290.542 0-057 0.705 0-773 12.43 0.058 0.718 0.786 12.64 0.033 0.408 0-459 12-43 4291.630 0.058 0.717 0-785 12.62 0.058 0.704 0.772 12.41 0.034 0.420 0.471 12.75 4294.936 0-058 0.717 0-785 12.62 0.058 0.717 0.785 12.62 0.034 0.420 0.471 12-75 = 74?8 = 79!8 = 79 :8 4196.699 0.032 0.410 0.461 12.48 0.019 0.247 0.287 11.51 0.018 0.236 0.276 1 1. 06 4197-257 0.029 0.372 0.423 "45 0.019 0.242 0.282 11.31 0.018 0.231 0.271 10.86 4203.730 0.031 0-397 0.448 12.13 O.O2O 0.257 0.297 11.91 0.019 0-247 0.287 11.51 4209.144 0.031 0.396 0.447 12.10 O.O2O 0.256 0.296 11.87 0.020 0.256 0.296 11.87 4216.136 0.030 0-382 0-433 11.72 0.019 0-238 0.278 11.15 O.OlS 0.234 0.274 10.98 4220.509 0.034 0.432 0.483 13.08 O.O2O 0-255 0.295 11.83 O.O2I 0.265 0-305 12.23 4232-887 0.032 0.405 0.456 12-34 O.O2O 0.249 0.289 "59 O.O2I 0.264 0.304 12.19 4257-815 0.034 0.426 0.487 I3-I9 0.021 0.259 0.299 11.99 O.O2O 0.251 0.291 11.67 4258.477 0.031 0.389 0.440 11.91 0.020 0-254 0.294 11.79 0.021 0.266 0.306 12.27 4265.418 0.032 0.400 0.451 12.21 O.O2O 0.246 0.286 11.47 O.Oig 0-243 0.283 "35 4266.081 0.034 0.424 0-475 12.87 O.O2O 0.271 0.311 12-47 O.O2O 0.246 0.286 "-47 4268.915 0.032 0-399 0.450 12.19 0.021 0.265 0-305 12.23 O.O2O 0-255 0.295 11.83 4276.836 0-035 0-435 0.486 13.16 O.O2O 0.254 0.294 11.79 0.019 0.240 0.280 11.23 4284.838 0.032 0-397 0.448 12.13 O.O2O 0.249 0.289 "59 O.O2O 0.244 0.284 "39 4287.566 0.034 0.421 0.472 12.78 O.O2O 0.248 0.288 "-5S O.O2O 0.244 0.284 "39 4288.310 0.036 0-445 0.496 13-43 0.020 0.248 0.288 "55 0.020 0.246 0.286 11.47 4290.377 0-035 0-433 0.484 13.10 O.O2O 0.243 0.283 "35 O.O2O 0.248 0.288 "55 4290.542 0.036 0-445 0-495 I3-40 O.O2O 0-253 0-293 "75 O.O2O 0.251 0.291 11.67 4291.630 0-035 0-433 0.484 13.10 O.Oig 0.241 0.281 11.27 0.020 0.248 0.288 "55 4294.936 0.034 0.420 0.471 12-75 0.020 0.243 0.283 "35 0.021 0.262 0.302 12. II RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907. 49 TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907 Continued. Plate w 85 Continued. 1907, May 30, 12" 5 G. M. T. Measured by L. on T. Distance from Limb i.o mm. Quality, good. p P ir n secy 2.8 O 68.4 O-O -6.0 P 16.3 15.2 26.2 15-2 26.2 74.8 63.8 I.OOI I.OOO D -0.7 Diameter 167.9 mm Factor 1.012 \ = 6 3 ?8 = 6 3 8 - 74!8 = 74?8 A v + v l A V " + ! A V + ! ? A D f + fj 1 km km km km km km km km 4196.699 0.049 0.627 0.695 ii. 18 0.048 0.613 0.68 1 10.95 0.030 0.385 0.436 11.81 0.029 0-371 0.422 "43 4197-257 0.049 0.640 0.708 11.38 0.048 0.613 0.681 10.95 0.031 0-397 0.448 12.13 0.029 0.371 0.422 n-43 4203.730 0.050 0.637 0.704 "34 0.052 0.664 0.732 11.77 0.032 0.406 0-457 12.37 0.030 0.384 0-435 11.78 4209.144 0.052 0.662 0.730 11.74 0.052 0.661 0.729 11.72 0.032 0-405 0.456 12.35 0.031 0-395 0.446 12.08 4216.136 0.051 0.647 0.715 11.50 0.050 0.634 0.702 11.27 0.030 0.382 0-433 11.72 0.030 0.382 0-433 11.72 4220.509 0-053 0.672 0-740 11.90 0.052 0.659 0.727 11.69 0.033 0.417 0.468 12.67 0.032 0.405 0.456 12-35 4232-887 0-053 0.669 0-737 11.85 0-053 0.661 0-737 11.85 0-033 0.417 0.468 12.67 0.032 0.405 0.456 12-35 4257-815 0-055 0.685 0-753 12. II 0-055 0.689 0-757 12.17 0.036 0.449 0.500 13-54 0.034 0-425 0.476 12.89 4258.477 0.053 0-659 0.727 11.69 0-053 0.661 0.729 11.72 0.034 0.423 0-474 12.83 0.033 0.387 0.438 11.86 4265.418 0.054 0.670 0.738 11.87 0.051 0.636 0.704 11-32 0.032 0-399 0.450 12.18 0-033 0-387 0.438 11.86 4266.081 0-055 0.683 0-751 I 2. 08 0.054 0.672 0.740 11.90 0-035 0-435 0.486 13.16 0.036 0.448 0-499 i3-5i 4268.915 0-054 0.670 0.738 11.87 0.054 0.670 0.738 11.87 0.032 0.398 0.449 12. l6 0.034 0.423 0-474 12.83 4276.836 0.054 0.670 0.738 11.87 0.051 0-633 0.701 11.27 0.033 0.410 0.461 12.48 0.031 0.386 0-437 11.83 4284.838 0-053 0.656 0.724 11.64 0-053 0-655 0.723 11.63 0-033 0.409 0.460 12.45 0.034 0.421 0-472 12.78 4287.566 0-053 0.655 0.723 11.63 0-054 0.667 0-735 11.82 0.032 0.396 0.447 12. IO 0-033 0.409 0.460 12.46 4288.310 0-053 0.655 0.723 11.63 0-053 0-655 0-723 11.63 0-033 0.408 0-459 12-43 0.034 0.421 0.472 12.78 4290.377 0.056 0.692 0.760 12.22 0.052 0-643 0.711 "43 0.034 0.420 0.471 12.75 0.032 0.396 0-447 12. IO 4290.542 0-055 0.680 0.748 12.03 0.054 0.667 0-735 11.82 0-033 0.408 0-459 12.43 0.034 0.420 0.471 12-75 4291.630 0.054 0.667 0-735 11.82 0.054 0.667 0-735 11.82 0.036 0.444 0-495 13.40 0.034 0.420 0.471 12.75 4294.936 0.052 0.642 0.710 11.42 0-053 0.654 0.722 ii. 61 0.034 0.420 0.471 12-75 0.033 0.408 0-459 12.43 Plate w 91. 1907, June 23, 5'' 55"" G. M. T. Measured by L. on T. Distance from Limb 1.2 mm. Quality, good. p P it i) Q Q-ii P D 91.1 16.7 6.4 2.1 37-0 52-7 68.2 83.2 37-o 52-7 68.2 83-2 53-o 37-3 21.8 6.8 3-4 2.6 2.2 2.1 I.OO2 I.OOI I.OOI I.OOI Diameter 168.1 mm Factor 1.014 = 6?8 = 2I?8 = 313 = S3?o A V D + Tj ( A V r + r, A tl + ! A V + ! km km km km o km km km km 4196.699 0.148 1.901 2-035 14-55 0.130 .669 .798 13-76 0.102 1.312 1.429 12.75 0.076 0.978 1.071 12.63 4197-257 0.148 I.OOO 2.034 14-55 0.130 .669 798 13-76 O.IO2 1.311 1.428 12.74 0.076 0-977 1.070 12.62 4203.730 0.150 1.919 2.053 14.68 0.132 .691 .820 13-93 O.IO4 I-33J 1.448 12.92 0.077 0.987 1.080 12.74 4209.144 0.150 1.917 2.051 14.67 0.132 .688 .817 13-91 O.IO4 1.328 r-445 12.89 0.078 i.ooo 1.093 12.89 4216.136 0.149 1.900 2.034 14-55 0.130 658 .787 13-67 O.IO4 1-325 1.442 12.87 0.078 0-997 .090 12.86 4220.509 0.150 1.906 2.040 14-59 0.132 .678 .807 13-83 O.IO4 1-325 1.442 12.87 0.078 0-995 .088 12.83 4232.887 0.150 I.OOI 2-035 H-55 0.132 673 .802 '3-79 0.105 1-332 1.449 12.93 0.078 0.990 083 12.78 4257-815 0.152 1.909 2.043 14.61 0-135 .691 .820 13-93 0.107 1-344 1.461 13-04 0.080 1.005 .098 12.95 4258.477 0.152 1.907 2.041 14.60 0-133 .667 .796 13-74 0.106 1-330 1.447 12.91 0.078 0.980 073 12.66 4265.418 0.152 1.905 2-039 14.58 0-133 -665 794 13-73 O.IO7 1-340 1-457 13.00 0.079 0.991 .084 12.79 4266.081 0.153 1.914 2.048 14.65 0.134 .677 .806 13.82 O.IOS 1-352 1.469 13.11 0.080 1.002 095 12.92 4268.915 0.152 1.892 2.026 14.49 0-134 .671 .800 13-77 O.IO7 I-324 1.441 12.86 0.080 I.OOO 093 12.89 4276.836 0.152 1.891 2.025 14.48 0-134 1.668 797 '3-75 O.IO/ 1.322 1-439 12.84 0.081 I.OIO -103 12.89 4284.838 0.152 1.889 2.023 14.46 0.134 1.666 795 13-74 0.107 I-33I 1.448 12.92 0.080 0-997 .090 12.86 4287.566 0-153 1.902 2.036 I4-56 O.I3S 1.677 .806 13.82 O.IO9 1-354 1.471 13-13 0.079 0-985 .078 12.72 4288.310 0.153 1.899 2.033 14-54 0.135 1.676 805 13.81 O.IO? 1.328 1-445 12.89 0.081 1.007 .100 12.98 4290.377 0.152 1.885 2.019 14.44 0.134 I-675 .804 13.80 o. 106 1.310 1.427 "73 0.080 0-995 .088 12.83 4290.542 0-153 1-895 2.029 I4-5I 0.136 1.686 -815 13.89 0.107 1.329 1.446 12.90 0.080 0-993 .086 12.81 4291.630 0.152 1.883 2.017 14.42 0.135 I-673 1.802 13-79 0.108 1.340 1-457 13.00 0.082 1.018 .III 13-" 4294.936 0.153 1.894 2.028 14.50 0.136 1.684 1.813 13-87 . 0.108 1-338 1-455 12.98 0.082 I.OIO 103 13.01 50 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907 Continued. Plate w 86. 1907, May 31, 4 h $$ m G. M. T. Measured by A. on G. Distance from Limb 1.3 mm. Quality, Good. t>-P seci o 69.1 8.9 8.9 81.1 4-4 1.003 0-0 -5-3 13- 9 9 76.1 2.8 I.OOI p 16.0 25- 9 25' 9 64.1 1.6 I.OOO D -0.6 45' ,2 45- a 44.8 0.9 I.OOO Diameter 168.5 mm 60 ,3 60, jj 29.8 0.8 I.OOO Factor 1.016 75' 2 75- 2 14.8 o-7 I.OOO = Mia = 20 = 44t8 X A li . + ., A V ,-,, A V . + ., 4196.699 0.143 km .837 km 1.971 14.47 0.116 km 1-493 km 1.617 13-23 0.095 km 1.225 km I-33I O I3-3I 4197.257 0.142 .826 1.960 14-39 O.I 20 1-544 1.668 13-65 0.092 1.183 1.289 12.89 4203.730 0.142 .827 1.961 14.40 0.119 I-525 1.649 13-48 0.094 1.208 I-3I4 I3-I4 4209.144 0.146 .874 2.008 14-74 0.124 1.582 1.706 13.96 0.098 1.249 355 13-55 4216.136 0.142 .809 1-943 14.27 0.116 1.481 1.605 13-13 0.096 1.226 332 I3-32 4220.509 0.146 .861 1-995 14.64 O.I2I 1.546 1.670 13.66 O.IOO 1.269 375 13-75 4232.887 0.147 1.863 1.997 14.66 0.123 1.564 1.688 13.81 0.091 1.160 .266 12.66 4257.815 0.143 1-793 1.927 14-15 O.I2I I.527 1.651 13-50 0.096 1.207 313 13-13 4258.477 0.149 1-873 2.007 14.74 0.125 1.569 1.693 13-85 O.IOO 1.262 .368 13.68 4265.418 0.148 1-855 1.989 14.61 O.I2I 'SIS 1.639 13-40 0.094 1.176 .282 12.82 4266.081 0.142 1-779 1-913 14.05 0.127 1-590 1.714 14.03 0.092 I-I54 .260 12.60 4268.915 0.146 1.824 1.958 14-38 0.123 1.538 1.662 13.60 0.092 1.162 .268 12.68 4276.836 0.147 1-833 1.967 14-45 0.127 1.584 1.708 13.98 0.095 1.188 294 12.94 4284.838 0.147 1.828 1.962 14.41 0.128 1-594 1.718 14.06 0.095 1.187 293 12.93 4287 566 0.144 I 7o6 I O3O 14.17 O.I23 I ^31 I ' ' " 's I2.C4. = 38!6 / A D + i A V +, e A t> + , i km km km km km km 4196.699 0.148 1.887 2.O2I 14.49 0.129 1.646 774 13.69 0.099 -265 1-379 "S3 4197-257 0.147 1.875 2.OO9 14.41 0.130 1.658 .786 13-77 O.IOO 277 I-39I 12.64 4203.730 0.149 1.896 2.030 14.56 0.132 1.679 .807 13-95 0.103 3" I-425 12.94 4209.144 0.150 1.901 2.035 14-59 0-133 1.689 .817 14.02 0.103 305 1.419 12.89 4216.136 0.148 1-875 2.OO9 14.41 0.130 1.647 775 13-70 O.IOI .280 1-394 12.66 4220.509 0.150 1.897 2.031 14-56 0.134 1.694 1.822 14.06 0.104 314 1.428 12.97 4232.887 0.150 1.889 2.023 14-51 0.133 I-675 1.803 13-92 0.103 .297 1.411 12.82 4257.815 0.153 1.905 2.039 14.62 0.136 1.696 1.824 14.08 0.106 .320 1-434 13-03 4258.477 0.152 1.890 2.O24 14-51 0.134 1.667 1-795 13-85 0.104 .297 1.411 12.82 4265.418 0.152 1.890 2.024 14-51 0-134 1.666 1-794 13-85 0.106 .312 1.426 12-95 4266.081 0-154 I-9I5 2.049 14.69 0-135 1.677 1.805 13-93 0.107 324 1.438 13.06 4268.915 0-IS3 1.895 2.029 14-55 0.134 1.664 1.792 13-83 0.107 323 1-437 13-05 4276.836 0.152 1.882 2.OI6 14.46 0.136 1.679 1.807 13-95 0.106 3" I-42S 12.94 4284.838 O.IS3 1.889 2.023 14-51 0.136 1.678 i. 806 13-94 0.105 .296 1.410 12.81 4287.566 0.152 1.876 2.010 14.41 0.136 1.677 1.805 13-93 o. 106 .308 1.422 12.92 4288.310 0.152 1.875 2.009 14.41 0-135 1.665 1-793 13.84 0.105 .294 1.408 12.79 4290.377 0.151 1.861 1-995 14-31 0.132 1.627 1-755 13-55 0.103 .270 1.384 12.57 4290.542 0.152 1-873 2.007 14.40 0.132 1.626 J-754 13-54 0.104 .281 1-395 12.67 4291.630 0.152 1.872 2.006 14-39 0.134 1.648 1.776 13-71 0.104 1.280 1-394 12.66 4294.936 0.153 1.882 2.016 14.46 0-133 1.636 1.764 13.62 0.104 1.280 1-394 12.66 = S2tl = 52!' = Srfi 4196.699 0.072 0.922 1.024 11.83 0.074 0.946 1.040 12.02 0.059 0-755 0.837 "57 4197-257 0.074 0.918 I.OI2 11.70 0.073 0-933 1.027 II.8? 0.060 0.767 0.849 11.74 4203.730 0.076 0.969 1.063 12.29 0.076 0.969 1.063 12.29 0.063 0.803 0.885 12.23 4209.144 0.075 0-954 1.048 12. II 0.076 0.967 1.061 12.26 0.062 0-789 0.871 12.04 4216.136 0.073 0.926 I.O2O 11-79 0.074 0-939 1-033 11.94 0.060 0.762 0.844 11.67 4220.509 0.076 0.963 1-057 12.22 0.076 0.963 1-057 12.22 0.062 0.786 0.868 11.99 4232.887 0.077 0.971 1.065 12.31 0.078 0.983 1.077 12-45 0.063 0.789 0.871 12.23 4257-815 0.080 0.999 1.093 12.63 0.080 0.999 1-093 12.63 0.064 0.800 0.882 12.19 4258.477 0.078 0.970 1.064 12.30 0.078 0-973 1.067 12-33 0.063 0.787 0.869 12.01 4265.418 0.078 0.969 1.063 12.29 0.078 0.972 1.066 12.32 0.063 0.785 0.867 11-99 4266.081 0.080 0.996 1.090 I 2. 60 0.078 0.971 1.065 12.31 0.065 0.807 0.889 12.29 4268.915 0.079 0-979 1-073 12.40 0.077 0.956 1.050 12.14 0.064 0.794 0.876 12. II 4276.836 0.078 0.967 1.061 12.26 0.077 0-955 1.049 12.13 0.065 0.806 0.888 12.28 4284.838 0.079 0.976 1.070 12.37 0.078 0.964 1.058 12.23 0.065 0.804 0.886 12.25 4287.566 0.078 0.966 i. 060 12.25 0.078 0.964 1.058 12.23 0.064 0.802 0.884 12.22 4288.310 0.078 0.965 1-059 12.24 0.077 0-954 1.048 12. II 0.064 0.791 0.873 12.07 4200.377 0.079 0.974 i. 068 12-34 0.077 0-952 1.046 I2.O9 0.063 0.778 0.860 11.89 4290.542 0.078 0.963 1-057 12.22 0.077 0.952 1.046 12.09 0.063 0.778 0.860 11.89 4291.630 0.079 0-973 1.067 12-33 0.077 0.952 1.046 I2.O9 0.064 0.789 0.871 12.04 4294.936 0.079 0-973 1.067 12-33 0.078 0.961 i-OSS 12.19 0.063 0.777 0.859 11.88 52 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907 Continued. Plate w 88. 1907, June 22, n h 40 G. M. T. Measured by L. on T. Distance from Limb 0.6 mm. Quality, good. P-P secy O Q-a p D 90.4 16.0 6.8 2.0 Diameter 167.0 mm Factor 1.007 30-9 30.9 S9-i 3-9 I.OO2 37-9 37-9 52-1 3-2 1.002 Si-4 Si-4 38.6 2.6 I.OOI 66.9 66.9 23-1 2.2 I.OOI 81.9 81.9 8.1 2.0 I.OOI \ 4> = 8 i = 23! i = 3!6 A A V + , 1 A v n + tij A t + , i km km O km km km km 4196.699 0.147 1.878 2.OI2 14-43 0.128 I-633 1.761 13-59 O.IOO 1.277 391 12.64 4197-25? 0.148 .888 2.O22 14-50 0.128 I-633 1.761 13-59 0.099 .264 -378 12.52 4203.730 0.150 .909 2.043 14.65 0-133 1.689 1.817 14.02 0.103 3" 425 12.94 4209.144 0.151 .917 2.051 14.71 0.131 1.664 1.792 13.83 O.IO2 295 .409 I 2. 80 4216.136 0.149 .888 2.O22 14.50 0.129 I-635 I-763 13.61 O.IOI .281 395 12.67 4220.509 0.152 .922 2.056 14.74 0.132 1.669 1-797 13.87 0.103 303 417 12.87 4232.887 0.152 .914 2.048 14.69 0.132 1.662 1.790 13.82 0.104 1.309 423 1293 4257-815 0-154 1.920 2.054 14-73 0-134 1.668 1.796 13.86 0.105 1.309 423 12.93 4258-477 0-153 1.901 2-035 14-59 0.132 1.643 .771 13-67 0.103 1.281 395 12.67 4265.418 0-153 1.899 2-033 14.58 0.132 1.642 .770 13-66 0.103 1.279 393 12.65 4266.081 0.154 1.909 2-043 14-65 0-135 1.677 -805 13-93 0.105 1.306 .440 13.08 4268.915 0.154 1.908 2.O42 14.64 0-135 1.676 .804 13.92 0.103 1.276 390 12.63 4276.836 0-153 1.894 2.028 14-54 0.132 1.634 .762 13.60 0.103 1.276 390 12.63 4284.838 0-153 1.885 2.019 14.48 0.134 1-654 .782 13-75 O.IO4 1.284 398 I2.7O 4287.566 0-153 1.885 2.019 14.48 0-133 1.639 .767 13-64 0.104 1-283 397 12.69 4288.310 0.154 1.896 2.030 14-56 0.133 1.639 .767 13.64 O.IO4 1.283 397 12.69 4290.377 0.152 1.871 2.005 14.38 0-133 1.638 .766 13-63 O.IO4 1.282 396 12.68 4290.542 0.152 1.882 2.016 14.46 0-134 1.650 .778 13.72 0.104 1.281 395 12.67 4291.630 0-154 1.894 2.O28 14-54 0.134 1.649 777 13-72 0.104 1.281 395 12.67 4294.936 0-153 1.882 2.0l6 14.46 0-133 1.636 .764 13.62 O.IO4 1.280 394 12.66 = s* = S2ti = S9?i 4196.699 0.074 0-949 1.043 12.05 0.073 0-937 1.031 11.92 0.059 0.758 0.840 11.61 4197-257 0.075 0.958 1.052 12. l6 0.074 0.946 1.040 12.02 0.060 0.768 0.850 n-75 4203.730 0.076 0.969 1.063 12.28 0.076 0.969 1.063 12.29 O.O62 0.790 0.872 12.06 4209.144 0.077 0.979 1.073 12.40 0.076 0.964 1-058 12.23 O.O62 0.788 0.870 12.03 4216.136 0.075 0.952 1.046 12.09 0.074 0-939 i-33 11.94 O.o6o 0.761 0.843 11.65 4220.509 0.077 0-975 1.069 12.36 0.077 0-975 1.069 12.36 0.063 0.797 0.869 I2.OI 4232.887 0.078 0-983 1.077 12.45 0.078 0.983 1.077 12-45 O.O62 0.781 0.863 n-93 4257-815 0.080 0-997 1.091 12. 6l 0.080 0.996 1.090 I 2. 60 O.O66 0.824 0.906 12-43 4258.477 0.079 0.983 1.077 12-45 0.078 0.971 1.065 12-31 O.O62 0.772 0.854 11.81 4265.418 0.079 0.982 1.076 12-44 0.079 0.982 1.076 12.44 0.063 0.783 0.865 12.95 4266.081 0.080 0.994 i. 088 12.57 0.080 0-994 i. 088 12-57 0.064 0-795 0.874 12.12 4268.915 0.079 0.981 1-075 12.42 0.079 0.980 1.076 12.44 0.064 0-794 0.876 12. II 4276.836 0.080 0.992 i. 086 12.55 0.080 0.992 i. 086 I2 .55 0.064 0-793 0.875 12. IO 4284.838 0.078 0.968 1.062 12.27 0.079 0.979 1-073 12.40 0.064 0.792 0.874 I 2.08 4287.566 0.080 0.988 1.082 12.51 0.079 0.978 1.072 12.39 0.064 0.791 0.873 I2.O7 4288.310 0.078 0.966 i. 060 12.25 0.080 0.988 1.082 12.51 0.063 0-779 0.861 11.90 4200.377 0.078 0.965 1.059 12.24 0.079 0.976 1.070 12.37 0.063 0.777 0.859 11.88 4290.542 0.079 0-975 1.069 12.36 0.080 0.987 1.081 12.49 0.064 0.789 0.871 12.04 4291.630 0.080 0.986 1.080 12.48 0.080 0.986 1.080 12.48 0.064 0.788 0.870 12.03 4294.936 0.081 0.997 1.091 12.61 0.082 I.OIO 1.104 12.76 0.063 0.776 0.858 11.86 RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907. S3 Plate w ! TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907 Continued. 1907, June 22, I2 h 15 G. M. T. Measured by L. on T. Distance from Limb 0.6 mm. Quality, good. p-P sec*) 90.4 3-5 30.5 59-5 3-9 1.003 o-n 16.0 37-5 37-5 52.5 3-2 1.002 p 6.8 51.0 51.0 39- 2.6 I.OOI D 2.O 66.5 66.5 23-5 2.2 I.OOI Diameter 167.0 mm. 81.5 8i.s 8-5 2.0 I.OOI Factor 1.007 = 8!s = 23!$ = 39! X A V v + v l A V + ! A V + ! km km o km km km km o 4196.699 0.146 -855 1.989 14.28 0.129 1.645 1-773 13-73 0.098 1.261 1-374 12-55 4I97-2S7 0.146 -855 1.989 14.28 0.128 I-633 1.761 13-63 0.099 1.269 1-382 12.62 4203.730 0.148 .875 2.009 14.42 0.132 1. 680 1. 808 13-99 O.IOI 1.285 1.398 12.79 4209.144 0.147 .863 1.997 14-34 0.132 1.676 1.804 13.96 O.IO2 1-295 1.408 12.86 4216.136 0.146 .850 1.984 14-23 0.130 1.647 775 13-75 O.IOI 1.281 1-394 12.73 4220.509 0.149 -877 2. on 14.44 0.133 1.682 .810 14.01 0.104 1.316 1.429 13-05 4232.887 0.148 .864 1.998 14-35 0.132 1.662 790 13.86 O.IO2 .285 1.398 12.77 4257-8IS 0.150 .871 2.005 14-39 0.136 1.693 .821 14.10 0.105 3" 1.424 13.01 4258.477 0.149 .856 1.990 14.28 0.134 1.667 795 13.90 0.104 .298 1.401 12.80 4265.418 0.150 -857 1.991 14.29 0.133 1.654 .782 13.80 0.106 317 1.430 13.06 4266.081 0.151 .870 2.004 14.38 0-137 1-703 .831 14.17 0.105 305 1.418 12.95 4268.915 0.148 .838 1.972 14.16 0.135 1.672 .800 13-93 0.104 .292 1.405 12.84 4276.836 0.150 855 1989 14.28 0.134 1.659 787 13.84 0.106 309 1.422 12.99 4284.838 0.150 853 1.987 14.27 0.134 1-653 .78! 13-79 0.104 .283 1.396 12.75 4287.566 0.149 .840 J-974 14.18 0-133 1.639 -767 13.68 0.106 .308 1.421 12.98 4288.310 0.148 .825 1-959 14.06 0-133 1.639 .767 13.68 0.104 .281 1-394 12.73 4290.377 0.146 1.800 1-934 13-88 0-132 1.626 754 13-58 0.103 293 1.406 12.84 4290.542 0.150 I-845 1-979 14.21 0.136 1.673 .801 13-94 0.106 304 1.417 12.94 4291.630 0.150 1.845 1-979 14.21 0.134 1.649 777 13.76 0.104 .280 1-393 12.73 4294.936 0.147 I-84S 1.979 14.21 0.133 1.636 764 13-66 0.104 .280 1-393 12.73 = 5z!s = 5z!s = 59!S 4196.699 4I97-2S7 0.074 0.074 0.950 0.950 1.044 1.044 12. 18 12.18 0.076 0.076 0.970 0.970 1.064 1.064 12.41 12.41 0.059 0.060 0.758 0.766 0.838 0.846 11.72 11.83 4203.730 0.076 0.970 1.064 12.41 0.077 0.980 1.074 12.53 0.062 0.792 0.872 12. 2O 4209.144 0.077 0.980 1.074 12.53 0.078 0.991 1.085 12.66 0.062 0.789 0.869 12. l6 4216.136 0.075 0.960 1.054 12.29 0.076 0.967 i. 06 1 12.37 0.061 0.778 0.858 12.00 4220.509 0.077 0.976 1.070 12.48 0.079 0.999 1.093 12-75 0.062 0.786 0.866 12. II 4232.887 0.078 0.984 1.078 12.57 0.078 0.983 1.077 12.56 0.062 0.778 0.858 I2.OO 4257.815 0.080 1. 000 1.094 12.76 0.080 0.998 1.092 12.74 0.065 0.812 0.892 12.48 4258.477 0.079 0.986 1.080 12.60 0.079 0.984 1.078 12.57 0.064 0.794 0.874 12.22 4265.418 0.079 0.985 1.079 12.58 0.081 1.009 1.103 12.86 0.065 0.805 0.885 12.38 4266.081 0.081 1. 006 I.IOO 12.83 0.082 1. 020 1.114 12.99 0.064 0-793 0.873 12.21 4268.915 0.080 0-993 1.087 12.68 0.097 0.980 1.074 12-53 0.064 0.792 0.872 12. 2O 4276.836 0.080 0-993 1.087 12.68 0.080 0.991 1.085 12.66 0.064 0.792 0.872 12. 2O 4284.838 0.081 1.003 1.097 12.79 0.080 0.988 1.082 12.62 0.065 0.803 0.883 12-35 4287.566 0.080 0.990 1.084 12.64 0.080 0.988 1.082 12.62 0.064 0.791 0.871 12. l8 4288.310 0.081 I.OOO 1.094 12.76 0.081 1. 002 1.096 12.78 0.064 0.791 0.871 12. l8 4290.377 0.080 0.988 1.082 12.62 0.081 I.OOO 1.094 12.76 0.063 0.778 0.858 I2.0O 4290.542 0.080 0.987 1.081 12. 6l 0.081 I.OOI 1.094 12.76 0.062 0.767 0.847 11.85 4291.630 0.082 I. Oil 1.105 12.89 0.08 1 0.998 1.092 12.74 0.063 0-777 0.857 11-99 4294.936 0.081 0.997 1.091 12.72 0.083 1. 02 1 1.115 13.00 0.063 0.777 0.857 11.99 54 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE 4. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1906-1907 Continued. Plate <> 90. 1907, June 23, s h zo m G. M. T. Measured by L. on T. Distance from Limb 1.2 mm. Quality, good. P-P scci) o o-n p D 91.1 16.7 6.4 2.1 Diameter 168.1 mm Factor 1.014 25-5 25.6 64.4 4.6 I.OO4 34-5 34-5 55-5 3-7 I.OO2 37-o S2.7 68.2 37-o S2-7 68.2 53- 37-3 21.8 3-4 2.6 2.2 I.OO2 I.OOI I.OOI 83-2 83-2 6.8 2.1 I.OOI = 6!8 = 2I8 = 3?!3 X A T + ?! t A V v + v l i A V V + tlj { km km km km km km 4196.699 0.149 I-9I3 2.047 14.64 0.128 1.646 1-775 13.58 0.102 1.312 1.429 12.75 4I97-2S7 0.149 I-9I3 2.047 14.64 0.129 I-657 1.786 13.67 O.IO2 1.311 1.428 12.74 4203.730 0.150 1.921 2-055 14.70 0.130 1.666 1-795 13-74 0.103 1.321 438 12.83 4209.144 0.151 1.925 2.059 14.72 0.130 1.662 1.791 13.70 O.IO4 1-330 447 12.91 4216.136 0.150 I-9I3 2.047 14.64 0.129 1.646 J-775 13-58 O.IO3 I-3I5 432 12.78 4220.509 0.150 1.909 2.043 I4.6l 0.130 1-655 1.784 13-65 O.IO4 1.324 .441 12.86 4232.887 0.151 I-9I3 2.047 14.64 0.130 1.648 1-777 13.60 0.105 1-332 449 12.93 42S7-8IS 0-153 1.920 2.054 14.69 0.131 1.651 1.780 13.62 O.IO4 1.307 1.424 12.70 4258.477 0.152 1.905 2.039 14.58 0.131 1.648 1-777 13.60 O.I 06 1-330 1.447 12.91 4265.418 0.152 1.002 2.036 I4-56 0.132 1.656 1-785 13.66 0.105 I.3I8 1-435 12.80 4266.081 0-153 I-9I3 2.047 14.64 0.132 1.654 1-783 13-64 0.106 1.328 1-445 12.89 4268.915 0.152 1.899 2-033 14-54 0.132 1.650 1-779 13.61 0.106 1.326 1-443 12.88 4276.836 0.152 1.897 2.031 I4-52 0.132 1.646 1-775 13.58 0.106 1.322 1-439 12.84 4284.838 0.152 1.894 2.028 14.50 0.132 1.644 1-773 13-57 0.106 1.320 1-437 12.82 4287.566 0-153 1.902 2.036 14.56 0-133 1.654 1-783 13.64 0.106 1.320 1-437 12.82 4288.310 0-153 1.899 2.033 14-54 0.134 1.664 1-793 13.72 0.106 1.318 1-435 12.80 4290.377 0.152 1.886 2.020 14-45 0-133 1.650 1.779 13.61 0.106 1.318 1-425 12.71 4290.542 O.IS3 1.896 2.030 14.52 0.132 1.652 1.781 13.63 0.107 I-327 1.444 12.88 4291.630 0.152 1.883 2.017 1442 0-133 1.647 1.776 13.59 0.105 1.302 1.419 12.66 4294.936 0.153 1.894 2.028 14.50 0-133 1.647 1.776 13.59 0.107 I-324 1.441 12.86 = S3!o = ss!s = 6 4 !4 4196.699 0.074 0-953 .046 12-34 0.071 0.912 i. 002 12.56 0.050 0.644 0.715 "75 4I97-257 0.075 0.964 057 12.47 0.072 0.925 1.015 12.72 0.050 0.644 0-715 "75 4203.730 0.077 0.987 .080 12-74 0.072 0.924 1.014 12.71 0.051 0.657 0.728 11.96 4209.144 0.076 0-973 .066 12.58 0.072 0.921 I. Oil 12.67 0.051 0.655 0.726 "93 4216.136 0.077 0.983 .076 12.69 0.072 0.919 1.009 12.65 0.050 0.641 0.712 11.70 4220.509 0.077 0.981 .074 12.67 0.073 0.930 I.O2O 12.78 0.051 0.651 0.722 11.86 4232.887 0.077 0.977 .070 12.62 0.073 0.926 1.016 12.73 0.052 0.661 0.732 12.03 4257-8I5 0.079 0-993 .086 12.81 0.075 0.941 1.031 12.92 0.054 0.680 0.751 12.34 4258.477 0.078 0.980 073 12.66 0.074 0.928 1.018 12.76 0.052 0-653 0.724 11.90 4265.418 0.078 0-979 .072 12.65 0.074 0.926 1.016 12.73 0-053 0.665 0.736 12.09 4266.081 0.078 0-977 .070 12.62 0.074 0.926 I .Old 12.73 0.054 0-677 0.748 12.29 4268.915 0.078 0-975 .068 12.60 0.073 0.912 I.OO2 12.56 0.054 0.675 0.746 12.26 4276.836 0.078 0-973 .066 12.58 0.074 0-923 I.OI3 12.70 0.054 0.674 0-745 12.24 4284.838 0.079 0.984 . -077 12.68 0.076 0.946 1.036 12.99 0.054 0.675 0.746 12.26 4287.566 0.079 0-983 .076 12.69 0.074 0.922 I.OI2 12.68 0.054 0.673 0.744 12.22 4288.310 0.080 o-995 .088 12.83 0.075 0.932 I.O22 12.81 0.053 0.661 0.732 12.03 4290.377 0.079 0.981 074 12.67 0.073 0.908 0.998 12.51 0.053 0.660 0-731 12.01 4290.542 0.080 0-993 .086 12.81 0.076 0-943 1-033 12-95 0.054 0.671 0.742 I2.I9 4291.630 0.079 0.979 .072 12.65 0.074 0.918 1. 008 12.63 0-053 0.658 0.729 11.98 4294.936 0.080 0.991 .084 12.79 0.074 0.917 I.OO7 12.62 0.052 0.646 0.717 ".78 The results for Plate w 91 are given on page 49. MEAN RESULTS FOR EACH PLATE FROM ALL LINES. OBSERVATIONS OF 1906-1907. 55 In order to arrange the results of Table 4 in a convenient form for effective discussion I have col- lected the values in three ways : (i) mean results for each plate from all lines ; (2) mean results for each latitude from all lines ; (3) mean results for each line from all plates. These summaries are found in Tables 5, 6, and 7. The values of v + v l and in Table 5 are the means for the separate values given in Table 4. Table 6 is a rearrangement of Table 5 and indicates the combination of points of latitude used in the derivation of normal positions. Table 7 is found directly from the values of the individual lines and forms the basis for a discussion of the behavior of the various lines employed. TABLE 5. MEAN RESULTS FOR EACH PLATE FROM ALL LINES. OBSERVATIONS OF 1906-1907. PLATE No. DATE. No. OF LINES. r + flj 1 PLATE No. DATE. No. OF LINES. + , J 1906 km lgo6 km <" 3 May 3 20 9.8 2.012 14.49 10 26 June 1 6 20 0.0 2.073 14.72 24.7 I.80S 14.11 15.0 1-977 14-52 39-7 I.4I9 13.10 30.0 1-637 13-41 54-6 1.004 12.31 45-0 1.276 1 2.80 69-5 0.598 12.12 60.0 0.861 12. 19 83-6 0.192 12.23 74-9 0.444 13.12 w 6 May 6 19 10.7 2-035 14.70 co 27 June 16 20 o.o 2.065 14.66 25-7 1-793 14-13 15.0 1-954 14.36 40.6 1.396 I3.5 30.0 1-657 13-59 55-6 0.990 12.44 45-o 1.270 12.75 70.4 0.589 12.47 60.0 0.827 11.74 84.6 0.177 13-35 74-9 0-435 11.85 + i 1 1906 O km i go? O km u 40 Dec. 1 8 20 0. 2.097 14.89 w 64 Apr. 7 20 77-5 0-363 11.92 O. iS- 2.103 1-974 14-93 14-51 w 67 Apr. 7 20 77-5 0-371 12. 16 iS- 1-977 14-53 w 78 Apr. 7 20 77-5 0.369 12.10 30. 30. 1.699 1.704 13-94 13.98 01 69 Apr. 7 20 77-5 0.369 12. IO w 41 Dec. 18 20 O. 2.086 14.81 w 81 Apr. 22 20 67.2 0.656 12.02 0. 2.076 14-74 67.2 0.649 11.89 IS- 1-957 14-38 72.5 0.501 11.83 iS- 1.960 14.40 72-5 0.497 "74 3- i-73 13-97 79-5 0.315 12.27 30- 1.690 13-87 79-5 0.3H 12.24 u 46 Dec. 1 8 20 44-4 1.294 12.86 "83 May 10 20 63-5 0.700 11.14 44-4 1.294 12.86 63-5 0.720 ii-45 44-4 1.298 12.90 74-4 0.465 12.28 59-4 0.884 12-33 74-4 0.436 11.51 59-4 0.892 12.44 79-2 0.302 11.44 59-4 0.892 12.43 79-2 0.300 iJ-37 047 Dec. 18 20 35-4 1-537 13-39 085 May 30 20 63.8 0.730 "74 35-4 1.516 13.20 63.8 0.722 11.62 44-4 1.308 13.00 74-8 0-454 12.30 Si-9 1.090 12.54 74-8 0.462 12.52 Si-9 i. 088 12.53 igO? S9-4 0.897 12.50 "85 May 30 20 63-8 0.782 12.58 w 50 Feb. 3 20 7-5 2-3 38.2 54- 69-5 2.01 1 1-835 I-SH I.OI4 0.604 14-39 14.18 13.68 12.25 12.25 63.8 74.8 74-8 79.8 79.8 0.792 0-474 0.464 0.291 0.289 12.75 12.82 12.56 11.67 11.58 77-8 0.3II 10.44 w86 May 31 20 14.8 1.966 14.44 77.8 0-333 u. 18 19 29.8 1.668 13-65 "55 Feb. 15 2O 7-5 2.049 14.67 20 44-8 1.304 13.04 22.4 1.847 14.18 20 64.1 0.770 12.52 38.3 1.464 13.22 20 76.1 0.408 12.06 u 56 Feb. 15 2O 7-5 2.012 14-43 2O 81.1 0.268 12.28 22.4 1.851 14.20 w 87 June 22 20 8.1 2.020 14-49 38.3 1-454 13.16 23.1 1-793 13.84 S4-o 1.040 12.56 38.6 1.411 12.82 69-S 0.612 12.41 52-1 1.059 12.24 to 60 Feb. 28 2O 6-5 2.043 14-59 52-1 1-055 12. 2O 6-5 2.046 14.62 59-i 0.869 12.01 20.4 28.1 1.841 1.679 13-94 13-52 u88 June 22 20 8.1 23.1 2.031 1.780 14.56 13-73 3S-o 1.512 13.10 38.6 1.401 12.74 43-7 1.285 12.62 52.1 1.071 12.38 5-5 1. 091 12.19 52-1 1.071 12.38 w 61 Feb. 28 16 43-7 1.265 12.42 59-i 0867 12. OO 18 18 17 18 SO-S 59-5 S9-S 6S-3 1.105 0.836 0.836 0.679 12-33 11.69 1 1. 69 11.53 089 June 22 20 8-5 23-5 39-0 1.986 1.787 1.405 14.26 13.84 12.84 17 18 18 65-3 65-3 6S-3 0.679 0.724 0.722 "S3 12.30 12.27 52-5 52-5 59-5 1.079 i. 086 0.866 12-59 12.67 12. II u> 62 Feb. 28 20 -6.0 2.042 14-57 o> 90 June 23 20 6.8 2.039 14.58 7-9 1.997 14-32 21.8 1.782 I3.63 15-6 1-993 14.69 37-3 1-437 12.82 22.S 1-789 13-75 55-5 1.015 12.71 30.2 I-655 13-59 53-o i-73 12.66 38-1 1.511 13.64 64.4 0-732 12.03 "63 Feb. 28 20 7.2 2.056 14.67 w 91 June 23 20 6.8 2-034 14-55 20.6 1.839 13-95 21.8 1.804 13.80 28.2 1.674 I3-48 37-3 1-447 12.91 35-i 1-535 13-32 53-o 1.089 12.84 So-7 1.058 11.86 43-8 1.283 12.63 MEAN RESULTS FOR EACH LATITUDE FROM ALL LINES. OBSERVATIONS OF 1906-1907. 57 TABLE 6. MEAN RESULTS FOR EACH LATITUDE FROM ALL LINES. OBSERVATIONS OF 1906-1907. PLATE PLATE PLATE PLATE No. P + P! 1 No. r PJ No. + p t 1 No. P + P, km > " km O km o km u 8 0.9 2.064 14.65 w 3 24.7 1.805 14.11 Si 62 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. A few modifications have been made in the list of lines used in the earlier investigation, with a view to the inclusion of certain lines of especial interest and the omission of some lines in the previous list which have no particular significance. The revised list consists of the 22 lines given in Table 8. Of the new lines in the list, \ 4207.566 is included because of its identification in Rowland's table as carbon (more accurately cyanogen). The appearance of the line under high dispersion, however, indicates that it is almost certainly of compound origin, and a similar conclusion is warranted by the size of its displacement at the sun's limb. The line X 4233.328 is of great interest becauseof being a very strong spark, or enhanced, line of iron and very prominent in the spectrum of the chromosphere. Two lines of calcium are added to the list for comparison with the so-called "blue line" at X 4227, as well as with other lines in the less refrangible part of the spectrum investigated by M. Perot by interference methods (17). Further reference will be made to these results in the course of the discussion. 7. RECORD OF OBSERVATIONS, 1908. The details of the observations given in Table 9 are taken from the observing journal and cover the 33 plates used in this investigation. The table is essentially the same as that given for the plates of 1906- 1907, the principal difference being that in the present series I have measured the diameter of the image and the distance of the slit inside the sun's limb directly, instead of computing them as in the previous case. The columns giving these values are found in the table immediately preceding the column containing the observations for zero. The use of a lens instead of a concave mirror, as in the case of the Snow telescope, has of course involved a correction in focusing the image on the slit of the spectrograph. This is readily found from the shape of the color curve for the lens, and it has been my practice before beginning the ob- servations to focus the image on the slit and then displace the lens by an amount corresponding to this difference for the region under investigation. The other columns in the table are self-explanatory. TABLE 9. RECORD OF OBSERVATIONS, 1908. DATE. HOUR G.M.T. PLATE No. DEFI- NITION. EX- POSURE TIME. SLIT WIDTH. DISTANCE INSIDE LIMB. DIAME- TER OF IMAGE. OBSERVATIONS FOR ZERO. EX- POSURE. READINGS POSITION CIRCLE. igo8 h m sec mm mm mm Feb. 16 II 10 w 103 4 210 0.038 0.5 172.4 142.1! (322.0 i 42.8 168.3 1 \ 348.2 2 27.8 3 12.8 4 357-8 5 342.8 6 327.8 7 312.8 Mar. 10 7 o ta 105 5 1 80 0.045 3-6 171.6 26.5 \ f 206.9 i 74-6 52.3) 1232.8 2 59-6 3 44.6 4 29.6 S 14.2 6 358-3 7 344-6 8 343-9 9 357-4 10 13.0 ii 28.7 Mar. 10 7 5 w 106 5 ISO 0.045 3.6 171.6 1 i AT, Q / 2 *to-y 58-9 4 73-9 S 58.9 6 43-9 7 28.7 8 13-0 9 357-4 10 343-9 RECORD OF OBSERVATIONS, 1908. TABLE 9. RECORD OF OBSERVATIONS, 1908 Continued. DATE. HOUR G. M. T. PLATE No. DEFI- NITION. EX- POSURE TIME. SLIT WIDTH. DISTANCE INSIDE LIMB. DIAME- TER OF IMAGE. OBSERVATIONS FOR ZERO. EX- POSURE. READINGS POSITION CIRCLE. 1908 h m sec mm mm mm O April 8 7 45 o 113 2-3 180 0.030 3.6 171.6 43-4 \_l 223.5 69.5 j \ 249.4 i 2 330.1 343-1 3 358.8 4 15.0 5 30.1 (> 45-1 7 60. i May 26 12 w 117 4 90 0.030 1.6 168.7 297.0 \ f 116.5 i 274.2 271.2) \ 90.8 2 287.7 3 303-2 4 319.0 S 334-* 6 349-2 7 364-2 8 364-2 9 349-2 10 334-2 ii 319.0 12 303-2 13 287.7 June 2 3 10 W I 2O 4 1 20 0-033 1.2 168.0 61.6 ) / 242.5 .87.5 f " I 268.3 I 2 312.7 326.2 3 341-7 4 357-2 5 12.7 (> 27.7 7 42.7 8 40.7 9 25-7 10 10.7 ii 355-2 12 339-7 13 324.2 14 310.7 June 9 12 SO u 128 2 105 0.033 i-5 166.0 269.3 \_1 88.6 294. 7 j \H4.i I 2 270.9 285-9 Taken at io h is m 3 300.9 4 3I5-9 5 330-9 6 345-9 7 o-9 June 10 8 IS <> 132 2 90 0-033 1.4 165.6 62.7 \ I 243-0 88.4 / \ 268.6 i 2 296.6 306.6 Taken at 3" o m 3 321.6 4 336.6 S 351.6 6 6.6 7 21.6 June ii j ^ w 134 4 90 0.033 2-5 1 68.0 62.91 (243.6 88.6 f 1269.3 i 2 295.8 305.8 3 320.8 4 335-8 5 350.8 6 5-8 7 20.8 8 25.8 Tune i i 4 CO W I 7 C 7C O O3? 2.1 167.4 i 295.8 5 /o ''-'OO *"/ **t 2 305.8 3 310.8 4 325.8 5 340.8 6 355.8 7 10.8 8 2S-8 64 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE 9. RECORD OF OBSERVATIONS, 1908 Continued. DATE. HOUR G. M.T. PLATE No. DEFI- NITION. EX- POSURE TIME. SLIT WIDTH. DISTANCE INSUJE LIMB. DIAM- ETER OF IMAGE. OBSERVATIONS FOR ZERO. EX- POSURE. READINGS POSITION CIRCLE. igog h m sec mm mm mm June ii 4 5 j 9 f 7 7C O 032. 2.1 167 4 i 258 * O / J * w / -^ 2 10.8 3 355-8 4 340.8 5 325-8 6 310.8 7 305-8 8 295.8 June ii 5 40 w 136 2 80 O.O32 i.S 167.0 i 295.8 ""*J 2 305-8 3 320.8 4 335-8 5 350.8 6 5-8 7 20.8 8 25.8 Aug. 5 9 So w 146 4 5 0.038 i-3 1 68.6 277.1 ) 1 96.8 i 327.8 302.7 1 1 122.5 2 342.8 3 357-8 4 '3-3 5 28.8 6 44-3 7 57-8 Aug. 5 10 30 w 147 3 7 0.038 1.4 1 68.6 i 57.8 2 . J / 44-3 3 28.8 4 13-3 5 357-8 6 342.8 ' 7 327.8 Aug. 5 10 30 w 148 3 7 0.038 1.4 168.6 i 527 8 2 o 1 *' 342.8 3 357-8 4 13-3 5 28.8 6 44-3 7 57-8 Aug. 6 5 15 u 151 3 70 0.038 i. s 168.6 56.2 \ f 236.7 i 278.4 82.0 1 1 262.4 2 291.9 3 307-7 4 323-2 5 338.4 6 353-4 7 8.4 Aug. 26 II ui6i 3 75 0.034 i.i 168.9 JOS- 1 I } 3"-7 i 42.1 131.1 1 I 285.8 2 17.7 3 1.7 4 346.3 5 33i-i 6 323-6 7 316.1 Aug. 26 II O l 162 3 75 0.034 i.i 168.9 i 316. i 2 o 3 331.1 4 346.3 5 1.7 6 17.7 7 42.1 RECORD OF OBSERVATIONS, 1908. TABLE 9. RECORD or OBSERVATIONS, 1908 Continued. DATE. HOUR G. M. T. PLATE No. DEFI- NITION. EX- POSURE TIME. SLIT WIDTH. DISTANCE INSIDE LIMB. DIAME- TER OF IMAGE. OBSERVATIONS FOR ZERO. EX- POSURE. READINGS POSITION CIRCLE. 1908 h m sec f mm mm mm e o e Aug. 26 II 55 w 163 3 90 0.0^4. I.I 168.0 i 42.1 *"*' 1 J*T ** y 2 17-7 3 i-7 4 346.3 S 33I-I 6 323-6 7 316.1 Aug. 26 II S5 w 164 3 oo O.O^d I.I 168.9 i 316. i O J o y w """"J"? Awu.y 2 J V 323-6 3 331-1 4 346.3 S i-7 6 17.7 7 42.1 Aug. 27 6 45 u 165 3 70 0.030 1.6 168.8 46.01 f253.2 72.4 / (226.8 i 2 280.6 305.0 3 320.9 4 336.4 S 3Si-6 6 359-1 7 6.6 Aug. 27 6 A< u> 1 66 3 7O O.O^O 1.6 168.8 i 6.6 *to O / v V>VJW 2 359-1 3 351-6 4 336.4 S 320.9 6 305-0 7 280.6 Sept. 30 II 40 <> 179 3 90 0.038 I.O 170.6 I2 4-7\_/ 34-6 5 45-5 150.8 ( 1330.7 6 45-5 Taken at io h 35 Sept. 30 II 40 w 180 3 90 0.038 I.O 170.6 3 45-S 4 45-5 Oct. 9 II o> 182 4 90 0.038 I.O 170.6 130-4 \ I 310-2 S 3I4-2 156.6 ( 1336-4 6 3I4-2 7 299.2 8 291.2 Oct. 9 II O w 183 A ne 0.0^8 I.O 170.6 i 291.2 t yj ta "^'O 2 299.2 3 314-2 4 3I4-2 S 299.2 6 291.2 7 291.2 8 299.2 Oct. 22 6 30 w 184 4 140 0.041 1-3 171.2 'QS-Sl/ iS-9 221.8 / \ 42.3 i 2 305-1 329.1 3 334-4 4 344-8 S 344-8 6 334-4 7 329-1 8 3i-i Oct. 22 6 ^o w 185 4. I4O 0.041 I. a 171.2 i SI.I v ,jw *T **T N ^ 'j 2 329.1 4 344-8 S 344-8 7 329-1 Oct. 22 7 4S 01 186 3 I4O 0.041 I.O 171.2 i 329.1 / *r J O LtfW 3 344-8 4 3i-i S 3i-i 8 329.1 66 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. The plates used in this investigation have been measured on the same instruments as those of the earlier series, and accordingly the previous discussion of the screw errors of these comparators is directly appli- cable in the present work. The process of measurement has also been identical in the two cases as well as the combination of the individual determinations to form the final means. In the present series the inclina- tion of the micrometer wire in the measuring comparator, determined by means of a plate taken with a long slit, is controlled by the exposure secured on the pole of the sun. The conversion of the measured displacements into linear velocity is made by means of Table 10, which is very similar to that given for the earlier observations, and differs from it only because of the difference in the linear scale of the plates. The quantities correspond to the displacements measured with the Toepfer comparator in units of the half- millimeter. TABLE 10. CONVERSION OF DISPLACEMENTS INTO VELOCITIES. OBSERVATIONS OF 1908. X ONE REVOLUTION IN ANGSTROMS. ONE ANGSTROM IN KM. ONE-HALF REVOLUTION IN KM. X ONE REVOLUTION IN ANGSTROMS. ONE ANGSTROM IN KM. ONE-HALF REVOLUTION IN KM. 4196.699 0.2996 71-45 IO.7O 4266.081 0.2984 70.29 10.49 4197-257 0.2996 71.44 IO.7O 4268.915 o. 2984 70.24 10.48 4203.730 0.2995 71-33 10.68 4276.836 0.2984 7O.II 10.46 4207.566 0.2994 71.27 10.67 4283.169 0.2982 7O.OI 10.44 4216.136 0.2992 71.12 10.64 4284.838 0.2982 69.98 10.43 4220.509 0.2992 71-05 10.63 4287.566 0.2982 69.94 10.43 4232.887 0.2988 70.84 10.58 4288.310 0.2982 69.92 10.43 4233-328 0.2988 70.83 10.58 4289.525 0.2982 69.90 10.42 4257-815 0.2986 70-43 10.52 4290.377 0.2982 69.89 10.42 4258.477 0.2986 70.42 10.51 4290.542 0.2982 69.89 10.42 4265.418 0.2984 70.30 10.49 4291.630 0.2982 69.87 10.42 It is unnecessary to consider further the various corrections to be applied to the observed linear veloci- ties to reduce them to the sun's sidereal period of rotation, or the computation of the latitudes, since the process of obtaining these is identical with that used in the previous reductions. Two important respects in which the observations of 1908 have a marked advantage over those in the earlier series have been referred to in the course of the description of the instrument. The first of these is in the quality of the sun's image formed by the object-glass of the telescope, and its comparative freedom from astigmatism and changes of focus during the exposures taken upon the plates. The importance of this source of error was dwelt upon strongly in the previous discussion of this subject, and the probability that it is largely, if not wholly, eliminated in the case of the tower telescope can not fail to be of the greatest possible value to the results obtained. The second advantage is in the relative stability of the diagonal- prism apparatus, which forms the images upon the spectrograph slit, and upon which the illumination of the grating depends. With the precautions taken in the first series of observations considerable changes of illumination could hardly have escaped detection, but sufficiently small changes might have done so, and accordingly it is a source of decided satisfaction that in the present series of determinations the danger of error from this source is also greatly reduced. A third important consideration has already been referred to, but may well be emphasized again. This is the presence on each plate of a spectrum of the edge of the sun corresponding to the projection of the pole. This furnishes a practical check on all of the adjustments of the instrument of the type so much to be desired in the measurement of small displacements. 8. RESULTS FOR THE INDIVIDUAL PLATES, 1908. The results for the individual plates are given in Table n in the same form as in Table 4 for the earlier observations, and the symbols employed are the same throughout. The sole difference in the constants of reduction used is that the value of the longitude of the ascending node of the sun's equator fl, has been modified by a slight correction corresponding to the precession for the two years intervening between the two sets of observations. The value employed is 74 26'. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908. 6 7 TABLE ii. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908. Plate u 103. 1908, Feb. 16, n h io m G. M. T. Measured by L. on T. Distance from Limb 0.5 mm. Quality, good. p P 7T 7) S6CJ) 0.2 Q 326.9 14.8 16.3 73-7 25-4 1.107 O-fi 252.4 29.8 30-5 59-5 13-7 1.029 P 17.8 44.8 45-2 44.8 9 .8 i. 015 D -6.9 59-8 60. i 29.9 8.0 I.OIO Diameter 172.4 mm 74.8 74-9 14.1 7.2 1.008 Factor 1.014 89.8 90.2 O.2 6.9 1.007 *. -:, *- * 0- .A A V .+,, A V . + 6 A V . + ., 4196.699 0.177 km 1-935 km 2.077 14-75 0.165 km 1-805 km 1.944 14-23 0.138 km 1.512 km 1.636 13-40 4197-257 0.178 1-945 2.087 14.82 0.165 1.805 1.944 14-23 0.138 I.5I2 1.636 I3-40 4203.730 0.176 1.920 2.062 14.64 o.i 66 I.8lO 1.949 14.27 0.140 I-53I 1-655 13-55 4207.566 0.177 1.928 2.070 14.70 o.i 68 1.826 1.965 14-38 0.140 1-542 1.666 13.64 4216.136 0.178 1-935 2.077 H-75 0.169 1.838 1.977 14.47 0.139 I-5I4 1.638 I3-4I 4220.509 0.180 1-954 2.096 14.88 o.i 68 .827 1.966 14-39 0.140 I-54I 1.665 13.64 4232.887 0.180 1.946 2.088 14.83 0.170 .841 1.980 14.49 0.142 1-538 1.662 13.61 4233.328 0.177 1-913 2-055 14-59 0.170 .840 1.979 14-49 0.140 1.518 1.642 13-45 4257-815 0.183 1.965 2.107 14.96 0.172 845 1.984 14-52 0.142 1.528 1.652 13-53 4258.477 0.179 1.922 2.064 14-65 0.171 .835 974 14-45 0.140 1.504 1.628 13-33 4265.418 0.180 1.928 2.070 14.70 0.167 .787 .926 14.10 0.140 I.S03 1.627 I3-32 4266.081 0.182 1.950 2.092 H.85 0.171 .832 .971 14-43 0.144 1.546 1.670 13.68 4268.915 0.180 1.926 2.068 14.69 o.i 68 .796 935 14.16 0.137 1.470 1-594 13-05 4276.836 0.182 945 2.087 14.82 o.i 68 795 934 14-15 0.142 I.5I7 1.641 13-44 4283.169 0.178 .898 2.040 14.48 0.169 .801 940 14.20 0.142 I-5I7 1.641 13-44 4284.838 0.180 .920 2.062 14.64 0.171 .821 .960 14-35 0.140 1-497 1.621 13.28 4287.566 0.181 .927 2.069 14.70 0.169 .800 939 14-19 0.142 I-5I5 1.639 I3-42 4288.310 0.182 939 2.081 14.78 0.167 .782 .921 14.06 0.142 I-SI5 1.639 13-42 4289.525 0.180 .917 2.059 14.62 o.i 66 770 .909 13-97 0.140 1-495 1.619 13.26 4290.377 0.180 .916 2.058 14.61 0.165 .760 .899 13-90 0.138 1.472 1.596 13.07 4290.542 0.180 915 2.057 14.60 0.167 .780 .919 14.05 0.141 1.504 1.628 13-33 4291.630 0.179 905 2.047 14-53 0.170 .809 .948 14.26 0.136 1-454 1.578 12.92 = 44!8 = sts = 73!? 4196.699 0.108 1.189 1.294 12.94 0.060 0.670 0.746 10.44 0.030 0.360 0.402 10.17 4197-257 0.108 1.189 1.294 12.94 0.060 0.670 0.746 10.44 0.032 0.384 0.426 10.78 4203.730 0.109 1.198 I-303 13-03 0.062 0.690 0.766 10.71 0.034 0.407 0.449 11.36 4207.566 0.109 1.191 1.296 12.96 0.062 0.689 0.765 10.70 0-035 0.419 0.461 11.66 4216.136 0.108 1.178 1.283 12.83 0.062 0.689 0.765 10.70 0.034 0.406 0.448 "33 4220.509 0.108 1.178 1.283 12.83 0.062 0.687 0.763 10.67 0.032 0.382 0.424 10.73 4232.887 0.108 1.176 1.281 12.81 0.064 0.703 0-779 10.90 0.034 0.404 0.446 11.28 4233-328 O.IIO 1.198 I-303 13-03 0.062 0.684 0.760 10.63 0.032 0.380 0.422 10.67 4257-815 O.II2 1.192 1.297 12.97 0.066 0.723 0.779 ii. 18 0-035 0.413 0-455 11.51 4258.477 0.108 1.168 1-273 12.73 0.065 0.713 0-789 11.04 0.032 0-377 0.419 10.60 4265.418 O.I 1 1 1.182 1.287 12.87 0.065 0.711 0.787 II.OI 0.032 0-377 0.419 10.60 4266.081 O.IIO 1.183 1.288 12.88 0.064 0.700 0.776 10.85 0.034 0.401 0-443 II. 21 4268.915 O.IIO 1.182 1.287 12.87 0.065 0.709 0.785 10.98 0.034 0.400 0.442 11.18 4276.836 O.I I I 1.192 1-297 12.97 0.064 0.699 0-775 10.84 0.034 0.400 0.442 ii. 18 4283.169 O.IIO 1.181 1.286 12.86 0.066 0.719 0-795 II. 12 0.032 0-375 0.417 10.55 4284.838 O.IIO 1.183 1.288 12.88 0.066 0.718 0-794 II. II 0-035 0.410 0.452 "43 4287.566 O.II2 1.208 I-3I3 I3-I3 0.064 0.698 0-774 10.83 0-035 0.410 0.452 "43 4288.310 O.II2 1.208 I-3I3 I3-I3 0.066 0.717 0-793 II.O9 0.034 0.398 0.440 "-13 4289.525 O.IIO 1.181 1.286 12.86 0.064 0.697 0-773 I0.8I 0.036 0.421 0.463 11.71 4290.377 0.108 I - I 57 1.262 12.62 0.062 0.674 0.750 10-49 0.034 0.398 0.440 11.13 4290.542 0.108 1.158 1.263 12.63 0.065 0.706 0.782 10-94 0.036 0.421 0.463 11.71 4291.630 O.IIO 1.179 1.284 12.84 0.064 0.696 0.772 10.80 0.034 0.398 0.440 11.13 68 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE n. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908 Continued. Plate w ios r 1908, March 10, 7 h o m G. M. T. Measured by A. on G. Distance from Limb 1.8 mm Quality, good. P-f secy Q O-Si P D 349-8 275-3 23-9 -7.2 Diameter 171.6 mm Factor 1.021 0.3 14.0 15-7 74-3 27.7 .129 29.9 3-7 59-3 14.2 .032 45-3 45-8 44.2 IO.I .016 60.3 60.6 29.4 8-3 .on 75-3 75-4 14.6 7-4 .008 9-3 9-3 - -3 7.2 .008 \ = - o!3 = 14^6 - 2 9!4 = 44!2 A A , + A , + I A 1! , + * A ,-M, i 4196.699 0.170 km 1. 880 km 2.O2O 14-31 0.170 km 1. 880 km 2.016 14.79 0.136 km 1.508 km .631 13-29 O.III km 1-237 km 1-338 13-25 4197-257 0.170 1.880 2.O2O 14-31 o.i 68 1.814 1.950 14-31 0.132 1-463 586 12.92 O.II2 1.248 1-349 I3-36 4203.730 0.176 1.942 2.082 14-77 o.i 68 1-854 1.990 14.60 0.136 I.505 .628 I3-27 O.I I 2 1-245 I-346 13-33 4207.566 o.i 68 1.852 1.992 14.14 0.170 1.874 2.OIO 14.74 0.132 1-459 .582 12.89 O.IIO 1. 221 1.322 13.09 4216.136 0.172 1.890 2.030 14-39 0.168 1.848 1.984 14-55 0.128 1.410 533 12.49 0.108 I.I97 1.298! 12.85 4220.509 0.172 1.889 2.O29 14-38 o.i 68 1.846 1.982 14-53 0.139 1.419 .642 13-37 0.113 1.239 340 13-27 4232-887 0.176 1.924 2.064 14.64 0.172 1.881 2.017 14.80 0.136 1.492 -615 I3.I6 O.IIO 1. 212 .313 13.00 4233-328 0.172 1.881 2.O2I 14-32 0.168 1.836 1.972 14.47 0.136 1.492 -615 13.16 O.IIO 1. 212 313 13.00 4257-815 0.180 1-955 2.095 14.87 0.172 1.869 2.OO5 14.71 0.140 I.525 .648 13-43 0.118 .292 393 13.80 4258.477 0.176 1.912 2.052 14-55 0.172 1.869 2.005 14.71 0.142 1.548 .671 13.62 0.116 .271 372 13-58 4265.418 0.174 1.886 2.026 14.41 0.172 1.865 2.001 14.68 0.138 1.500 .623 I3-23 0.116 .268 369 13-55 4266.081 0.178 1.930 2.070 14.69 o.i 68 1.821 r-957 14-36 0.136 1.476 599 13.02 O.I I 2 .223 324 13.11 4268.915 0.180 1.949 2.089 14-83 0.174 1.884 2. 02O 14.82 0.140 1.520 643 13-37 0.116 .266 367 13-53 4276.836 0.180! 1.945] 2.085 14.80 0.172 1.858 994 14.63 0.146 1.582 70S 13.89 0.114 .241 342 13-29 4283.169 0.180 1.941] 2.081 14-77 0.172 1.854 990 14.60 0.140 I-5I3 636 1340 0.116 .260 .361 13-47 4284.838 0.180 1.941 2.081 14-77 0.172 1.854 .990 14.60 0.136 1.470 593 12.99 O.I I 2 .217 .318 13-05 4287.566 0.180 1.940 2.O8O 14.76 o.i 68 1.810 946 14.28 0.144 I-556 .679 I3-65 0.117 .270 371 13-57 4288.310 0.178 1.917 2.057 14-59 0.172 1.852 .988 14.58 0.140 1.512 635 I3-32 0.116 259 360 13-46 4289.525 0.180 1-939 2.079 14-75 0.172 1.852 .988 14-58 0.144 1-554 .677 I3-63 0.118 .280 381 13-67 4290.377 0.176 1.894 2.034 14.42 0.172 1.852 .988 14.58 0.140 1.511 1-634 I3-3I 0.108 .172 .273 12.59 4290.542 0.180 1.938 2.078 14.74 o.i74 1.872 2.008 14-73 0.144 1-554 1.677 13-63 0.119 .291 392 13-78 4291.630 0.184 1.960 2.IOO 14.91 0.170 1.830 1.966 14-43 0.146 I-576 1.699 I3-84 0.116 1-259 .360 13.46 = S93 = 74!3 = -3* = i4?6* 4196.699 0.066 0.749 0.820 11.40 0.029 0.372 0.408 10.70 0.173 1.909 2.049 14-54 0.163 1.800 1.936 14.21 4197-257 0.070 0-794 0.865 12.03 0.029 0.372 0.408 10.70 0.177 1-952 2.092 14.86 0.164 1.809 1-945 14.28 4203.730 0.070 0.790 0.861 11.97 0.031 0.398 0-434 "39 0.177 948 2.088 14.83 0.165 1.816 1-952 14.33 4207.566 0.060 0-745 0.816 "35 0.027 0.346 0.382 IO.O2 0.176 936 2.076 14-74 o.i 66 1.825 1.961 14-39 4216.136 0.068 0.765 0.836 11.63 0.028 0.356 0.392 10.28 0.178 952 2.092 14.86 o.i 68 1.843 1-979 14-52 4220.509 0.070 0.787 0.858 "93 0.033 0.418 0-454 11.91 0.179 .960 2.IOO 14.90 0.167 1.829 1.965 14.42 4232.887 0.068 0.763 0.834 1 1. 60 0.031 0-394 0.430 11.28 0.178 942 2.082 14.78 0.168 1.832 1.968 14.44 4233-328 0.066 0.741 0.812 11.29 0.028 0-355 0.391 IO.26 0.178 .942 2.082 14.78 0.170 1.854 1.990 14.61 4257-815 0.072 0.802 0.873 12.14 0.032 0.402 0.438 11.49 0.182 973 2.II3 I5.OO 0.172 1.863 1.999 14.67 4258.477 0.068 0.758 0.829 "53 0.028 0-342 0.378 9.92 0.179 .940 2.080 14.76 0.173 1.874 2.010 14-75 4265.418 0.072 0.800 0.861 11.97 0.032 0.414 0.450 n.8i 0.177 .914 2-054 14-57 0.169 1.827 1.963 14.41 4266.081 0.068 0.756 0.827 11.50 0.032 0.414 0.450 11.81 0.180 .946 2.086 I4.8l 0.173 1.869 2.OO5 14.72 4268.915 0.070 0.778 0.849 11.81 0-035 0.451 0.487 12.78 0.180 944 2.084 14-79 0.169 1.823 1-959 14-37 4276.836 0.072 0.798 0.869 12.08 0.032 0.412 0.448 "75 0.181 951 2.091 14.85 0.170 1.832 1.968 14.44 4283.169 0.072 0.796 0.867 12.05 0.030 0.390 0.426 11. 18 0.180 936 2.076 14-74 0.172 1.849 1-985 14-59 4284.838 0.068 0.752 0.823 11.44 0.030 0.390 0.426 n. 18 0.179 925 2.065 14.65 0.170 1.827 1.963 14.41 4287.566 0.072 0.796 0.867 12.05 0.030 0.390 0.426 11. 18 0.180 936 2.O76 14.74 0.169 1.816 1-952 14-33 4288.310 0.070 0.774 0.845 "75 0.029 0.361 0-397 10.42 0.180 935 2.075 14-73 0.170 1.826 1.962 14.40 4289.525 0.070 0-774 0.845 "75 0.029 0.361 0-397 10.42 0.180 934 2.074 14.72 0.171 1.838 1-974 14.48 4290.377 0.072 0-794 0.865 12.03 0.030 0.386 0.422 11.07 0.179 .922 2.062 I4.63 0.172 1.847 1.983 14-55 4290.542 0.072 0-794 0.865 12.03 0.029 0.360 0.396 10.39 o.i 80 932 2.072 14.71 0.172 1.846 1.982 14-54 4291.630 0.070 0-773 0.844 11.74 0.028 0-349 0.385 IO.IO 0.182 953 2.093 14.87 0.171 1.836 1.972 14.47 * Measured by L. on T. The results for Plate w l 5i are continued on page 70. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908. 6 9 TABLE n. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908 Continued. Plate w 105.,. 1908, March 10, 7 h o' n G. M. T. Measured by A. on G. and L. on T. ; upper half of table by A., lower by L. Distance from Limb 1.8 mm. Quality, good. P-P seer/ 349.8 -0.4 o-n 275.3 59-6 59-9 3- 1 8.4 I. Oil p 23.9 74.6 74.8 15-2 7-5 i.ooq D -7.2 89.6 90.4 -0.4 7-2 1. 008 Diameter 171.6 mm Factor 1.021 \ = o4 = o 4 = IS!2 = }OI A A j) + v l A I) -f Dj A p + Dj A tl + , I 4196.699 0.168 km 1.868 km 2.008 14.28 0.172 km I-9I3 km 2-053 14-58 0.164 km 1.815 km I-95I M-35 0-138 km 1-530 km I-653 o 13-56 4197-25? 0.172 1-913 2-053 14-5* 0.172 1.903 2.043 14-51 0.166 1.836 1-972 I4-5I 0.136 I.5I9 1.642 13-47 4203.730 0.172 1.898 2.038 14.48 0.178 1.963 2.103 14.94 o.i 68 1.854 1.990 14. (>{ 0.138 1.526 1.649 13-53 4207.566 0.176 1-95' 2.091 14.86 0.172 1.907 2.047 14-54 o.i 66 1.820 1.956 14-39 0.132 1-459 1.582 12.99 4216.136 0.170 1.868 2.008 14.28 0.172 1.902 2.042 14.50 0.162 1.782 1.918 14.10 0.136 1.498 1.621 13-30 4220.509 0.174 1.911 2.051 14-56 0.176 0-944 2.084 H-79 o.i 68 1.834 1.970 14.49 0.140 i-54i 1.664 13-67 4232.887 0.176 1.936 2.076 14.76 0.176 1.924 2.064 14-51 0.168 1-837 1-973 14-51 0.142 1-456 1-579 12-97 4233-328 0.172 1.881 2.021 14-37 0.176 1.914 2.054 H-59 0.168 1.816 1-952 14.36 0.140 1-545 1.668 13-70 4257-815 o.iSo 1-945 2.085 14.82 0.176 1.923 2.063 14.65 0.166 1.805 1.941 14.27 0.142 1.546 1.669 I3-7I 4258.477 o.iSoj 1.945 2-085 14.82 0.176 1-945 2-085 14.82 0.172 1.858 1.994 14.67 0.146! 1.590 I-7I3 14-05 4265.418 0.176; 1.918 2.058 14.61 0.180 1.908 2.048 14-54 o.i 68 1.822 1-958 14.40 0.144 1-565 1.688 13-85 4266.081 o.iSoj 1.940 2.080 14.78 0.176 1.940 2.080 14.78 0.168 1.822 1.958 14.40 0.148 1-597 1.720 14.11 4268.915 0.182 1-973 2-II3 15.00 0.180 1.971 2. Ill 14.99 0.166 1.799 1-935 14-23 0.144 1-574 1.697 13-93 4276.836 O.I 80 1.956 2.096 14.89 0.182 1-935 2.075 14-75 0.170 1-837 1-973 14-51 0.144 1.561 1.684 13.82 4283.169 O.I 80 i-95i 2.091 14.86 0.180 1.941 2.081 H-79 o.i 68 1.802 1.938 14.25 0.144 1-558 1.681 13-80 4284.838 0.182 1.963 2.103 14.94 0.180 1.941 2.081 14.79 o.i 60 1-737 1-873 13-79 0.144 1-568 1.691 13-88 4287.566 0.180 1.950 2.090 14.85 0.180 1.929 2.069 14.71 o.i 68 1.822 1.958 14.40 0.148 1.598 1.721 14.12 4288.310 0.180 1.928 2.068 14.72 0.180 1.938 2.078 14-77 0.168 1.811 1.947 14-32 0.144 I-556 1.679 I3-78 4289.525 0.184 1.971 2. Ill 14.99 0.180 1.948 2.088 14-83 0.172 1.842 1.978 14-55 0.148 1.598 1.721 14.12 4290.377 0.180 1.949 2.089 14.84 0.176 1.884 2.024 14-39 0.168 1-799 1-935 14-23 0-144 1-543 1.666 13-70 4290.542 0.178 1.916 2.056 14.60 0.182 1.958 2.098 14.90 0.170 1.831 1.967 14.47 0.150 1.630 1-753 14-39 4291.630 0.192 1.970 2. no 14.98 0.180 1-937 2.077 14-77 o.i 68 1.820 1.956 14-39 0.148 1-597 1.720 14.11 = o?4 = o4 = IS?2 = 3o!i 4196.699 0-173 1.009 2.049 14-55 0.170 1.876 2.016 14-32 0.165 1.821 1-957 14-39 0.138 1.526 1.649 13-53 4197-257 0.176 1.942 2.082 14.78 0.172 1.897 2.037 14-47 0.166 1.831 1.967 14.46 0.140 1-547 1.670 I3-72 4203.730 0-175 1.926 2.066 14.68 0-175 1.926 2.066 14.68 0.167 1.825 1.961 14.42 0.141 i-55i 1.674 I3-76 4207.566 0.176 1-935 2-075 14-74 0.177 1-945 2.085 14.80 o.i 66 1.821 J-957 14-39 0.141 i-SSo 1-673 13-75 4216.136 0.174 1.908 2.048 14-54 0.176 1.930 2.070 14.70 0.165 i.8n 1.947 14-32 0.138 i-5i7 1.640 13-44 4220.509 0.178 1-945 2.085 14.80 0.177 1.938 2.078 14.76 0.168 1-835 1.971 14.49 0.141 1.548 1.671 13-73 4232.887 0-179 1-952 2.092 14.86 0.178 1.942 2.082 14.78 0.168 1-833 1.969 14.48 0.143 1.564 1.687 I3-87 4233-328 0.178 1.942 2.082 14.78 0.176 1.919 2.059 14.63 o.i 68 1-833 1.969 14.48 0.140 1-530 1-653 I3-56 4257-815 0.180 i-95i 2.091 14.84 0.180 I-95I 2.091 14.84 o.i 68 1.821 1-957 H-39 0.141 1-532 1-655 13-58 4258.47? 0.181 1.961 2.IOI 14.92 0.180 1.950 2.090 14.83 0.169 1.832 1.968 14-47 0-143 1-547 1.670 I3-72 4265.418 0.179 1-935 2-075 14-74 0.179 J-935 2.075 14.74 0.170 1-833 1.969 14.48 0.143 1-547 1.670 I3-72 4266.081 0.180 1.938 2.078 14.76 0.178 1.924 2.064 14.66 o.i 68 1.817 1-953 14-36 0.143 1-547 1.670 I3-72 4268.915 0.180 1-937 2.077 14-75 0.180 1-943 2.083 14.78 0.170 1.831 1.967 14.46 0-143 1-545 1.668 I3-70 4276.836 0.180 t-937 2.077 14-75 0.179 1.929 2.069 14.70 0.170 1.830 1.966 14-45 0.143 1-545 1.668 I3-70 4283.169 0.180 1-935 2-075 H-74 0.180 1-935 2.075 14.74 0.170 1.830 1.966 14-45 0.142 I-53I 1.654 13-57 4284.838 0.180 1-935 2.075 14.74 0.180 1-935 2.075 14-74 0.170 1.829 1.965 14-45 0.142 I-53I 1.654 '3-57 4287.566 0.182 1-957 2.097 14.89 0.180 1-934 2.074 14-73 0.172 1.850 1.986 14.60 0.144 '554 1.677 13-79 4288.310 0.182 1.956 2.096 14.88 0.181 1-943 2.083 14.78 0.170 1.829 1.965 14-45 0.143 1.540 1.663 I3-65 4289.525 0.181 1-945 2.085 14.80 0.181 1-944 2.084 14-79 0.171 1-837 1-973 14-51 0.144 1-554 1.677 '3-79 4290.377 0.180 1-935 2.075 14.74 0.180 I-93I 2.071 14.72 0.170 1.827 1.963 14-43 0.144 1-552 I-67S 13-77 4290.542 0.182 1-955 2.095 14.89 0.182 1-955 2.095 14.89 0.172 1.848 1.984 14-59 0.145 1.561 1.684 13.84 4291.630 0.182 1.954 2.094 14.88 0.182 1-954 2.094 14.88 0.172 1.847 1.983 I4-58 0.148 1-594 1.717 I4-I3 70 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE n. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908 Continued. Plate 105, Continued. Measured by L. on T. = 2g?4 = 44?2 = S93 - 74?3 A r + ; A V P + tlj A V v + r, 1 A + !>! km km km km km km km km 4196.699 0.139 1-535 1-658 13-51 0.108 I.2OI 1.302 12.89 0.066 0.746 0.817 11.36 0.028 0-347 0-383 10.05 4197-257 0.138 1-524 1.647 13-43 0.108 I.2OI 1.302 12.89 0.068 0.767 0.838 11.65 0.028 0-347 0.383 10.05 4203.730 0.139 1-534 I-657 13-50 O.IIO .219 1.320 13-07 0.067 0-754 0.825 11.47 0.026 0-337 0-373 9-79 4207.566 0.141 1-554 1.677 13.66 0.113 253 1-354 13-41 0.067 0-754 0.825 11.47 0.027 0-347 0-383 10.05 4216.136 0.138 1.518 1.641 13-37 0.108 .194 1.295 12.82 0.068 0.763 0.834 "59 0.027 0-347 0-383 10.05 4220.509 0.140 1-538 1.661 13-54 0.114 259 1.360 13-47 0.069 0.770 0.841 11.68 0.028 0-354 0.390 10.23 4232-887 0.143 1.564 1.687 13-75 O.IIO .209 1.310 12.97 0.068 0-759 0.830 ii-54 0.028 0-353 0.389 10.21 4233-328 0.142 1-552 1-675 13-65 0.113 .242 1-343 13-30 0.067 0.748 0.819 "39 0.029 0-363 0-399 10.47 4257-815 0.143 1-554 1.677 13-66 0.113 235 I-336 13.23 0.070 0.772 0.843 11.71 0.030 0-375 0.411 10.78 42.58-477 0.140 1.522 1.645 13.40 0.114 .244 1-345 13-32 0.070 0.772 0.843 11.71 0.031 0.390 0.426 II.I8 4265.418 0.142 1-538 1.661 13-53 0.115 253 1-354 13-41 0.070 0.771 0.842 11.70 0.028 0-365 0.401 IO.52 4266.081 0.142 1-537 i. 660 13-52 0.117 274 1-375 13.62 0.068 0.752 0.823 11.44 0.030 0.378 0.414 10.86 4268.915 0.142 i -S3 6 659 13-51 O.I I 2 .218 I-3I9 13.06 0.070 0.770 0.841 11.68 0.028 0.364 0.400 10.49 4276.836 0.142 1-535 .658 13-50 O.II2 .217 1-3'S 13-05 0.070 0.770 0.841 11.68 0.029 0.376 0.412 10.81 4283.169 0.144 1-553 .676 13.66 O.II7 .268 1.369 13-56 0.070 0.770 0.841 11.68 0.029 0.376 0.412 10.81 4284.838 0.141 1.522 645 13.40 0.116 .260 1.361 13-48 0.072 0-793 0.864 12.02 0.029 0.376 0.412 10.81 4287.566 0.142 i-53i 654 13-48 0.116 2-59 1.360 13-47 0.072 0-793 0.864 I 2. 02 0.028 0-363 0-399 10.47 4288.310 0.143 1-542 -665 13-56 0.115 247 1.348 13-35 0.070 0.770 0.841 11.68 0.028 0.363 0-399 10.47 4289.525 0.143 1-542 -665 13-56 0.117 .266 1.367 13-54 0.071 0.780 0.851 11.83 0.028 0-363 0-399 10.47 4290.377 0.142 1-53 1-653 13-47 0.116 .256 1-357 13-44 0.070 0.769 0.840 11.67 0.028 0-363 0-399 10.47 4290.542 0.143 1.540 1.663 13-54 0.114 234 1-335 13.22 0.073 0.801 0.872 12.13 0.030 0.388 0.424 II. 12 4291.630 0.145 1.561 1.684 13.72 0.118 .286 1-387 13-74 0.071 0-779 0.850 11.82 0.030 0.387 0.423 II. IO Plate w 106. 1908, March 10, 7 h 50"" G. M. T. Measured by L. on T. Distance from Limb 1.8 mm. Quality, good. P-F sec'n O 349.9 -0.4 o-n 275.4 13-1 14.9 75-i 29-3 1.147 P 23.9 28.7 29.6 60.4 14-7 1.034 D -7.2 44-4 44-9 45-i 10.3 1.016 Diameter 171.6 mm 59-6 59-9 30.1 8.4 I. Oil Factor 1.021 74-6 74-8 15-2 7-5 1.009 ^ = I52 = 3 i = t5i* = 6o?4* A V V+ ; A V f + !>i A V + flj A V 11 + ! t s km km km km km km km km 4196.699 0.166 1.833 1.969 14.49 0.137 'SIS 1-638 13-44 O.I I 2 1.248 1-347 13-55 0.064 0-737 0.806 11.58 4I97-257 0.166 1.832 1.968 14.48 0.139 533 656 13-59 0.108 1.204 I-303 13.11 0.064 0.727 0.796 11-45 4203.730 0.169 1. 860 1.996 14.67 0.140 544 .667 13.68 O.II2 1.256 355 13-63 0.066 0.747 0.816 11.72 4207.566 o.i 68 1.848 1.984 14.60 0.140 543 .666 13-67 0.104 I-I55 254 13.62 0.064 0-713 0.782 11.23 4216.136 0.166 1.822 1.958 14.41 0.138 517 .640 13.46 0.108 .186 -285 12.93 0.068 0-755 0.824 11.84 4220.509 o.i 68 1-837 1-973 14.52 0.141 548 .671 13-71 O.II2 239 -338 13.46 0.068 0-754 0.823 11.83 4232.887 o.i 68 1.835 1.971 14.50 0.141 541 1.664 13.65 0.106 .168 .267 12.75 0.064 0.707 0.776 11.14 4233-328 0.168 1-834 1.970 14.49 0.140 530 i-*53 13-57 O.IIO .212 3" 13-19 0.066 0.740 0.809 11.62 4257-815 0.169 1-835 1.971 14.50 0.143 554 1.677 13-75 O.II2 -237 -336 13-44 0.066 0.725 0.794 11.42 4258.477 0.170 1.843 1.979 14.56 0.142 542 1.665 13-66 O.IIO .204 303 13.11 0.064 0.702 0.771 11.08 4265.418 0.169 1.828 1.964 14.46 0.141 525 1.648 13-52 O.II4 245 344 13-52 0.066 0-734 0.803 n-54 4266.081 0.170 1.836 1.972 14.51 0.142 534 1-657 13.60 O.II2 -234 333 13-41 0.066 0-734 0.803 "54 4268.915 0.170 I-835 1.971 14.50 0-143 547 1.670 13-70 0.116 -254 353 13.61 0.066 0-733 0.802 "53 4276.836 0.170 1.834 1.970 14.49 0.141 .522 1.645 13-50 O.IIO .198 .298 13-05 0.066 0.722 0.791 11.40 4283.169 0.169 1.820 1.956 14.40 0.142 i.53i 1.654 13-57 O.IIO 1.196 295 13-03 0.066 0-730 0.799 11.49 4284.838 0.170 1.830 1.966 14.47 0.141 1.520 1.643 13.48 0.108 I.I74 273 12.81 0.064 0.707 0.776 11.15 4287.566 0.172 1.850 1.986 14.61 0.143 1-542 1.665 13.66 O.II2 1.184 283 12.91 0.066 0.720 0.789 "34 4288.310 0.170 1.830 1.966 14.47 0.142 1-533 1-656 13-59 O.II2 1.226 1-325 13-33 0.066 0.730 0.799 11.49 4289.525 0.171 1.840 1.976 14-54 0.143 1.540 1.663 13.64 O.II2 1.205 1.304 13.12 0.062 0.685 0-754 10.83 4290.37? 0.170 1.828 1.964 14-46 0.142 1-529 1.652 13-56 O.IlS 1.161 1.260 12.69 0.064 0.695 0.764 11.07 4290.542 0.171 1.839 1-975 14-53 0.142 1.528 1.651 13-55 0.116 1.247 I-346 13-54 0.064 0.705 0.774 II. 12 4291.630 0.172 1.848 1.984 14.60 0.144 i-SSO 1-673 13-72 0.116 1.247 1.346 13-54 0.064 0-705 0.774 II. 12 * Measured by A. on G. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908. TABLE n. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908 Continued. Plate = 7S?i \ A V ,+,, 1 A V + , A V v 4- v l A V , + ., 4196.699 0.030 km 0.377 km 0.411 n-35 0.108 km 1.189 km 1.288 12.96 0.058 km 0.656 km 0.725 e 10.65 0.028 km 0.351 km 0-38 = 10.63 4197.257 0.028 0.366 0.400 11.04 0.108 1.189 1.288 12.96 0.058 0.656 0.725 10.65 0.029 0.361 0-395 10.91 4203.730 0.032 0.400 0-434 11.98 O.I 08 1.196 1-295 13-03 0.058 0-655 0.724 10.64 0.029 0.361 0-395 10.91 4207.566 0.030 0.376 0.410 11.32 0.108 I-I95 1-295 13.02 0.060 0.676 0-745 10.80 0.030 0.369 0-403 11.13 4216.136 0.030 0-375 0.409 11.29 0.109 1.204 I-303 13.11 0.058 0-653 0.722 10.62 0.030 0.369 0.403 11.13 4220.509 0.036 0-437 0.471 13.00 0.108 1.188 1.287 12.95 0.060 0.672 0.741 10.71 0.031 0.380 0.414 11.44 4232.887 0.032 0.414 0.448 12.37 0.108 1.187 1.286 12.94 0.061 0.682 0.751 10.85 0.030 0.368 0.402 II. IO 4233-328 0.028 0-335 0.369 10.19 0.109 1.197 1.296 13.04 0.060 0.671 0.741 10.71 0.030 0.368 0.402 II. 10 4257-815 0.032 0.392 0.426 11.76 O.IIO 1.200 1.299 13-07 0.062 0.687 0.756 10.91 0.030 0.366 0.400 11.05 4258.477 0.032 0.392 0.426 11.76 O.IIO i. 200 1.299 13-07 0.062 0.687 0.756 10.91 0.030 0.366 0.400 11.05 4265.418 0.028 0.360 0-394 10.88 0.108 1.176 1-275 12.83 0.062 0.687 0.756 10.91 0.031 0.376 0.410 11-33 4266.081 0.032 0-393 0.427 11.79 O.II2 1.219 1.318 13.26 0.061 0.677 0.746 10.78 0.032 0.386 0.420 1 1. 60 4268.915 1 0.030 0.370 0.404 11.15 0.109 1-185 1.284 12.92 0.062 0.686 o-755 10.90 0.032! 0.386 0.420 1 1. 60 4276.836 0.032 0.380 0.414 "43 O.IO8 I.I74 1-273 12.81 0.062 0.686 0-755 10.90 0.031 0-375 0.400 11.30 4283.169 0.032 0-379 0.413 11.40 O.IIO: I.2O2 1.301 13.09 0.062 0.686 0-755 10.90 0.031 0-375 0.400 11.30 4284.838 0.032 0-379 0.413 11.40 O.lOg 1.181 1.280 12.95 0.063 0.696 0.765 11.13 0.032 0.386 0.420 1 1. 60 4287.566 0.032 0-379 0.413 11.40 O.IIO 1.193 1.292 13.00 0.062 0.685 0-754 10.89 0.032 0.386 0.420 n. 60 4288.310 0.032 0-379 0.413 11.40 O.IIO 1.192 1.291 12.99 0.062 0.685 0-754 10.89 0.032 0.385 0.410 11-57 4289.525 0.032 0.402 0.436 12.04 O.IIO 1.192 1.291 12.99 0.063 0.695 0.764 II. 12 0.032 0-385 0.410 n-57 4290-377 0.030 0.368 0.402 II. 10 O.IIO 1.190 1.289 12.97 0.060 0.661 0.730 10.72 0.030 0.364 10.99 4290.542 0.032 0.368 0.402 II. IO O.II2 1. 212 1.311 13-19 0.063 0-693 0.762 II. 10 0.032 0.384 0.418 "-S5 4291.630 0.034 0.389 0.423 11.68 O.I I 2 1. 212 1.311 13-19 0.062 0.683 0.752 10.87 0.030 0.363 0-395 10.97 = 45! i = 6o4 *-** , A V . + ., A V M-,, * A V . + ., 4196.699 0.108 km 1. 201 km 1.300 13 08 0.062 km 0.703 km 0.772 11.09 0.028 km 0.351 km 0.385 10.63 4197-257 0.108 1. 201 1.300 13 08 0.062 0.703 0.772 11.09 0.030 0.376 0.410 II-33 4203.730 0.108 I.I98 297 I3-05 0.063 0.713 0.782 11.24 0.030 0-373 0.407 11.24 4207.566 O.IIO I.2I9 .318 13 26 0.063 0.711 0.780 II. 21 0.028 0-349 0.383 10.58 4216.136 O.IIO I.2I5 -3H 13 22 0.064 0.720 0.789 "34 0.028 0-349 0-383 10.58 4220.509 0.109 1.203 .302 13 IO 0.064 0.719 0.788 11.32 0.029 0-359 0-393 10.86 4232.887 O.IIO I.2O9 .308 '3 16 0.065 0-730 0.799 11.48 0.029 0-359 0-393 10.86 4233-328 O.IIO I.2O9 -308 13 16 0.067 0.750 0.819 11.77 0.030 0.371 0.405 11.19 4257-815 O.III 1. 212 3" 13 19 0.066 0-734 0.803 n-53 0.032 0-393 0.427 11.79 4258.477 O.IIO 1. 201 .300 13.08 0.066 0-734 0.803 "53 0.031 0.380 0.414 11.44 4265.418 O.IIO I.2OO .299 I3-07 0.067 0-743 0.812 11.67 0.029 0-354 0.388 10.72 4266.081 O.IIO I.I99 .298 13 06 0.066 0.732 0.801 11.50 0.032 0-392 0.426 11.77 4268.915 O.III I.2O7 .306 13 14 0.066 0-731 0.800 11.48 0.030 0.365 0-399 11.02 4276.836 O.III I.2O4 303 13.11 0.066 0.730 0.799 11.47 0.032 0.392 0.426 11.77 4283.169 O.IIO I-I93 .292 13 .00 0.067 0.740 0.809 11.63 0.031 0-379 0.413 11.41 4284.838 O.IIO I.I94 293 13 .01 0.066 0.729 0.798 11.46 0.032 0.391 0.425 11-74 4287.566 O.IIO I.I94 293 13 01 0.066 0.729 0.798 11.46 0.032 0.391 0.425 11.74 4288.310 O.II2 1.203 .302 13 .10 0.067 0.738 0.807 1 1. 60 0.032 0.391 0.425 11.74 4289.525 O.III 1.203 1.302 13 .10 0.067 0.738 0.807 1 1. 60 0.031 0.380 0.414 11.44 4290.377 O.IIO I-I93 1.292 13.00 0.065 0.717 0.786 11.30 0.030 0.368 0.402 II. II 4290.542 O.II2 1. 212 1.311 I3-I9 0.066 0.728 0.797 11.44 0.030 0.368 0.402 II. II 4291.630 O.III I.2OI 1.300 13-08 0.068 0.749 0.818 11.76 0.030 0.367 0.401 II.O9 * Measured by A. on G. 72 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE n. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908 Continued. Plate w 113. 1908, April 8, 7 h 45 G. M. T. Measured by A. on G. Distance from Limb 1.4 mm. Quality, good. t-P seci) O 1 8.6 O-D 304.1 I P 26.5 D -6.0 Diameter 170.7 mm Factor 1.017 0.0 13.0 14-3 75-7 25.0 1.103 28.7 29-3 60.7 12.3 1.024 44-9 45-2 44.8 8.6 1. 01 1 60.0 60.2 29.8 6.9 1.007 7S-o 75-i 14.9 6.2 i. 006 90.0 90.0 o.o 6.0 i. 006 = oo , = , 4 : 9 = 2Q?8 A V V + fj 1 A V ,+,, 1 A ' , + ,, k 4196.699 0.176 km 1.919 km 2.056 14.60 0.164 km 1.788 km L923 14.12 0.136 km 1.487 km I.6n 13-18 4197-257 0.180 1-973 2. no 14.99 o.i 66 1.820 1-955 14-37 0.140 1-529 I-653 13-56 4203.730 0.182 1.990 2.127 15.11 0.168 1.837 1.972 14.48 0.144 1-567 1.691 13.84 4207.566 0.180 1.967 2.104 14-95 0.164 1.804 1-939 14.24 0.140 1-532 1.656 13-58 4216.136 0.176 1.918 2.055 14-59 0.164 1.788 1.923 14.12 0.138 1.502 1.626 13-30 4220.509 o.i 80 1.960 2.097 14.89 0.172 1.862 1-997 14.68 0.144 1.562 1.686 13.81 4232.887 0.184 1.984 2. 121 15.06 0.172 1.876 2.OII 14.78 0.144 1-572 1.696 13.88 4233-328 0.180 1-951 2.088 14.83 0.166 I.8oo 1-935 14.21 0.136 1-479 1.603 13.12 0.184 1.971 2.108 14.98 0.174 1.86 3 1.998 14.68 0.146 1-566 1.690 13.84 4258.477 0.182 1.960 2.097 14.89 0.172 1.842 1.977 14-52 0.146 1-583 1.707 13-97 4265.418 0.184 1.987 2.124 15.09 0.170 1.827 1.962 14.41 0.148 1.588 1.712 14.01 4266.081 0.184 1.977 2.II4 15.02 0.172 1.849 1.984 14.58 0.146 1-573 1.697 13.89 4268.915 0.084 1-975 2. 112 15.01 0.172 1.857 1.992 14-63 0.148 1-587 1.711 14.00 4276.836 0.188 2.003 2.140 15.22 0.172 1.854 1.989 14.61 0.148 1.596 1.720 14.07 4283.169 0.184 1-977 2.II4 15.02 0.176 I.88I i. 202 14.82 0.152 1.627 i-75i 14-31 4284.838 0.180 1-934 2.071 14.71 0.176 1-775 1.910 14.03 0.140 1.498 1.622 13-27 4287.566 0.184 1.966 2.103 14.94 0.170 1.816 I-95I 14-33 0.144 1.541 1-665 13.60 4288.310 0.184 1-954 2.091 14.85 0.176 1.879 1. 201 14.80 0.148 1-572 1.696 13.88 4289.525 0.184 1.965 2.IO2 H-93 0.172 1.848 1.983 14-57 0.146 1.562 1.686 13-91 4290.377 0.184 1-953 2.090 14.84 o.i 68 1.794 1.929 14.17 0.148 1.582 1.706 13.96 4290.542 0.184 1.964 2.IOI 14-93 0.172 1.836 1.970 14.47 0.144 i-5Si 1-675 13-72 4291.630 0.182 1.942 2.079 14.76 0.172 1.847 1.982 14.56 0.144 I-S5I 1-675 13-72 = 448 = 60^7 = 7S!7 4196.699 0.104 J-I35 1.239 12-39 0.066 0.736 O.SlO 11.76 0.028 0-325 0.366 10-54 4197-257 0.108 1.202 1.306 13.06 0.066 0.725 0.799 n.6o 0.026 0.314 0-355 IO.22 4203.730 0.108 I.I76 1.280 12.80 0.068 0-745 0.8l9 11.89 0.024 0-303 0-344 9.92 4207.566 0.104 I-I53 1-257 12.57 0.066 0.723 0.797 "57 0.024 0.302 0-343 9.88 4216.136 0.106 1.161 1.265 12.65 0.068 0-743 0.817 11.86 0.028 0-323 0.364 10.48 4220.509 0.108 I-I93 1.297 12.97 0.066 0.805 11.70 0.028 0.346 0.387 11.14 4232.887 0.116 1. 210 L3I4 13-14 0.064 0.706 0.780 11.23 0.028 0.321 0.362 IO.42 4233-328 0.108 I.lS? 1.291 12.91 0.064 0.718 0.792 11.50 0.024 0.300 0.341 9.82 4257-815 0.116 1-245 1-349 13-49 0.066 0.724 0.798 "59 0.028 0-343 0.384 1 1. 06 4258.477 O.I 12 1. 212 1.316 13.16 0.066 0.724 0.798 "59 0.028 0-332 0-373 10.74 4265.418 0.108 1.167 1.271 12.71 0.064 0.711 0.785 11.40 0.028 0.321 0.362 IO.42 4266.081 O.II2 1.220 I-324 13-24 0.064 0.711 0.785 11.40 0.028 0-331 0-372 10.72 4268.915 o.iio I.lS? 1.291 12.91 0.068 0.742 0.816 11.85 0.030 0-352 0-393 11.31 4276.836 O.II2 1. 2O6 1.310 13.10 0.070 0.763 0.837 12.15 0.028 0.320 0.361 10.40 4283.169 0.108 1.161 1.265 12.65 0.068 0.751 0.825 11.98 0.028 0.340 0.381 10.97 4284.838 O.IIO 1.182 1.286 12.86 0.068 o.75i 0.825 11.98 0.028 0.330 0-371 10.68 4287.566 0.116 1.246 1-350 13-50 0.066 0.718 0.792 11.50 0.024 0.286 0-327 9.42 4288.310 O.IIO 1.182 1.286 12.86 0.068 0.728 0.802 11.65 0.026 0.307 0.348 10.02 4289.525 0.116 1-245 1-349 13-49 0.066 0.706 0.780 11.23 0.028 0.317 0-358 IO.3I 4290.377 O.II2 i. 202 1.306 13.06 0.064 0.706 0.780 11.23 0.026 0.296 0-337 9.71 4290.542 O.II2 1. 212 1.316 13.16 0.066 0.716 0.790 II-37 0.026 0.307 0.348 10.02 4291.630 O.II2 I.I90 1.294 12.94 0.068 0.728 0.802 11.65 0.024 0.296 0-337 9.71 RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908. 73 TABLE n. RESULTS TOR INDIVIDUAL PLATES. OBSERVATIONS or 1908 Continued. Plate w 113 Continued. Measured by L. on T. *- oo *- I49 *- 2Q8 A tl Mi A V M-i A ' V + V l km km i km km km km 4196.699 0.175 1-934 2.071 14.70 0.162 .784 1.919 14.10 0.140 1-533 I-657 13-55 4197.257 0.177 1-935 2.072 14.71 o.i 66 .815 1-950 14-33 0.142 I-556 1. 680 13.74 4203.730 0.182 , 1-984 2. 121 15.06 o.i 68 834 1.969 14.47 0.144 1-574 1.698 13.89 4207.566 0.179 .961 2.098 14.89 o.i 66 .810 1-945 14.29 0.144 572 1.696 13.59 4216.136 0-177 .924 2.061 14-63 o.i 68 .827 1.962 14.41 0.145 .580 1.704 13.94 4220.509 0.179 943 2.080 14-77 0.169 835 970 14.47 0-145 577 1.701 13.92 4232.887 0.180 947 2.084 14.79 0.172 .847 .982 14.56 0.145 571 1.695 13.87 4233-328 0.180 945 2.082 14.78 o.i 68 .817 952 14-34 0.145 570 1.694 13.86 4257-815 0.181 953 2.090 14.84 0.169 -825 .960 14.40 0.146 1-574 1.698 13.89 4258.477 0.181 945 2.082 14.78 0.171 .840 975 14-5 I 0.146 I-57I 1.695 13.87 4265.418 0.181 939 2.076 14-73 0.171 -8.34 .969 14.47 0.144 1.546 1.670 13.66 4266.081 0.180 939 2.076 14-73 0.170 -825 .960 14.40 0-145 I-556 1.680 13-74 4268.915 0.180 937 2.074 14.72 0.172 .846 .981 14-55 0.146 1.566 1.690 13.83 4276.836 0.181 925 2.062 14.64 0.171 .827 .962 14.41 0-145 1-553 1.677 13.72 4283.169 0.181 938 2-075 14-73 o.i73 .848 983 14-57 0.144 1-539 1.663 13.61 4284.838 0.183 .948 2.085 14.80 o.i 68 .792 1.927 14.16 0.144 1-537 1.661 13-59 4287.566 0.182 940 2.077 14.74 0.171 -823 1.9158 14-38 0.146 I-558 1.682 13.76 4288.310 0.182 .938 2-075 14-73 0.173 843 1.978 14-53 0.145 1.548 1.672 13.68 4289.525 0.184 958 2.095 14.87 0.169 .801 1.936 14.22 0.144 1-537 1. 66 1 13.59 4290.377 0.183 1.947 2.084 14.79 0.169 .801 1.936 14.22 0.147 1-567 1.691 13.83 4290.542 0.182 1-937 2.074 14.72 o.i75 .860 1-995 14.66 0.148 1-578 1.702 13.92 4291.630 0.183 1.948 2.085 14.80 0.173 .842 1.977 14.52 0.142 LSI4 1.638 13.40 *- 44^8 *- 60!? #- 7S!7 4196.699 0.106 1.165 .269 12.69 0.064 0.712 0.786 11.42 0.024 0.288 0.329 9-47 4197-257 0.109 1.198 .302 13.02 0.063 0.701 0-775 11.25 0.026 0.309 0.350 10.07 4203.730 O.IIO 1.206 .310 13.10 0.065 0.721 o-795 11-55 0.027 0.319 0.360 10.36 4207.566 0.109 I-I95 299 12.99 0.066 o-73i 0.805 11.69 0.026 0.307 0.348 IO.OI 4216.136 o.i 06 I-I59 .263 12.63 0.064 0.708 0.782 11.36 0.027 0.318 0-359 10.33 4220.509 0.108 1.179 .283 12.83 0.065 0.717 0.791 n-49 0.026 0.307 0.348 IO.OI 4232.887 O.IIO 1.196 .300 13.00 0.066 0-725 0.799 1 1. 60 0.028 0-332 0-373 10.74 4233-328 o.i 06 I-I53 1-257 12.57 0.067 o.737 0.811 11.78 0.028 0-332 0-373 10.74 4257-815 O.I II i. 200 1.304 13-04 0.067 0.732 0.806 11.70 0.028 0.330 0-371 10.68 4258.477 O.I II 1.199 I.303 13-03 0.066 0.721 0-795 "55 0.028 0-330 0-371 10.68 4265.418 O.IIO 1.188 1.292 12.92 0.065 0.710 0.784 "39 0.026 0.308 0-349 10.04 4266.081 0.113 1.217 1.321 13.21 0.065 0.709 0.783 11.38 0.026 0.308 0-349 10.04 4268.915 O.II2 1.206 1.310 13.10 0.067 0.730 0.804 11.66 0.029 0-339 0-379 10.91 4276.836 O.I 12 1.204 1.308 13.08 0.066 0.718 0.792 11.50 0.028 0.328 0.369 10.62 4283.169 O.IIO 1-183 1.287 12.87 0.066 0.717 0.791 "49 0.028 0.328 0.369 10.62 4284.838 O.IIO 1.182 1.286 12.86 0.066 0.716 0.790 11.48 0.029 0-339 0.380 10.93 4287.566 O.IIO 1.180 1.284 12.84 0.067 0.727 0.801 11.63 0.028 0.328 0.369 10.62 4288.310 O.IIO 1.179 1.283 12.83 0.066 0.717 0.791 11.49 0.029 0.338 0-379 10.91 4289.525 O.I I 2 i. 200 I-304 13.04 0.066 0.716 0.790 11.48 0.028 0.328 0.369 10.62 4290.37? O.III o.i 88 1.292 12.92 0.061; 0.705 0.779 11.32 0.026 0.307 0.348 IO.OI 4290.542 O.II2 1.199 I-303 13-03 0.068 0-735 0.809 n-74 0.028 0.328 0.369 10.62 4291.630 O.II2 1.199 13-03 0.066 0.716 0.790 11.48 0.029 0.338 0-379 10.91 74 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE n. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908 Continued. Plate a ii7 r 1908, May 26, I2 h o m G. M. T. Measured by L. on T. Distance from Limb 1.6 mm. Quality, good. *-* 7T n sec)) o6 6 S -3 14.1 I4.I 75-9 4-7 1.003 O-O 350.1 29.6 29.6 60.4 2-3 I.OOI P 17-4 45-4 45-4 44.6 1.6 i.ooo D -1.8 60.6 60.6 29.4 1.4 I.OOO Diameter 168.7 mm 75-6 75-6 14.4 1.2 I.OOO Factor 1.019 90.6 0.6 -0.6 I.I I.OOO = -ot = M.% = 2Q 4 , A , + * A V . + ' A V 1) -\- 1) t S 4196.699 0.173 km 1.887 km 2.021 14-35 0-159 km 1-735 km 1.868 13.69 0.138 km I.507 km 1.632 1.3-30 4197-257 0.172 1.877 2.0II 14.28 o.i 60 1-745 1.878 13-77 0.138 1.506 1.631 I3-30 4203.730 0.176 I-9I5 2.049 14-55 0.163 1.762 1.895 13.89 0.142 1-545 1.670 13-61 4207.566 0.177 1.924 2.058 14.61 0.161 1-747 i. 880 13-78 0.142 544 1.669 13.61 4216.136 0.175 1.898 2.032 14-43 0.161 1-745 1.878 13-77 0.139 .508 1-633 I3-3I 4220.509 0.178 1.928 2.062 14.64 0.163 1.764 1.897 13-91 0.140 Si? 1.642 I3-38 4232.887 0.179 1.930 2.064 14.66 0.164 1.768 1.901 13-94 0.143 543 1.668 13.60 4233-328 0.178 1.920 2.054 14.58 0.164 1.767 1.900 13-93 0.141 522 1.647 13-43 4257-815 0.182 I-95I 2.085 14.80 0.168 1.797 1.930 14-15 0.145 554 1-6-79 13.69 4258.477 0.179 1.918 2.052 14-57 0.165 1.766 1.899 13.92 0.144 544 1.669 13.61 4265.418 o.i 80 1.924 2.058 14.61 o.i 66 .767 1.900 13-93 0.143 528 1-653 13-47 4266.081 0.181 1-934 2.068 14.68 0.166 .776 1.909 13-99 0.146 .560 1.685 13-74 4268.915 0.180 1.920 2.054 14.58 0.166 .765 1.898 13-91 0.146 559 1.684 13-73 4276.836 0.182 1.941 2.075 14-73 0.166 .765 1.898 13-91 0.143 523 1.648 13-43 4283.169 0.178 1.896 2.030 14.41 0.167 775 1.908 13-99 0.144 532 1-657 13-Si 4284.838 0.181 1.924 2.058 14.61 0.166 .767 1.900 13-93 0.145 542 1.667 13-59 4287.566 0.181 1.923 2.057 14.61 0.165 743 1.876 13-75 0.144 531 1.656 13-50 4288.310 0.182 1-934 2.068 14.68 0.165 755 1.888 13.84 0.146 552 1.677 13-67 4289.525 0.182 1-933 2.067 14.68 0.165 755 1.888 13.84 0.146 551 1.676 13-66 4290.377 0.182 1-933 2.067 14.68 0.165 754 1.887 13-83 0.146 550 1-675 13-65 4290.542 0.182 1.932 2.066 14.67 0.167 774 1.907 13.98 0.147 .561 1.686 13-74 4291.630 0.184 1-954 2.088 14-83 0.166 0.764 1.897 13.90 0.148 570 1.695 13.82 = 44?6 = ao !4 = ,* 4196.699 0.108 1.178 1.285 12.82 0.068 0.741 0.822 11.82 0.029 0.307 0-355 10-35 4197-257 O.I 08 1.178 1.285 12.82 0.067 0.731 0.812 11.68 0.028 0.307 0-355 10-35 4203.730 0.108 I-I73 1.280 12.77 0.069 0.751 0.832 11.96 0.030 0.329 0-377 10.99 4207.566 O.IIO 1.194 1.301 12.98 0.073 0-793 0.874 12.57 0.029 0.318 0.366 10.67 4216.136 0.108 1.171 1.278 12-75 0.068 0.738 0.819 11.78 0.029 0.317 0-365 10.64 4220.509 O.IIO 1.190 1.297 12.94 0.070 0.758 0.839 12.07 0.030 0.327 0-375 10.93 4232.887 O.IIO 1.186 1.293 12.90 0.070 0-754 0.835 12.01 0.030 0-325 0-373 10.87 4233-328 O.II2 1.208 I-3'S 13.12 0.069 0-744 0.825 11.86 0.029 0.314 0.362 10.55 4257-815 O.II2 1. 201 1.308 I3-04 0.072 0.771 0.852 12.25 0.030 0.322 0.370 10.79 4258.477 O.II4 1. 221 1.328 I3-25 0.070 0.751 0.832 11.96 0.032 0.346 0-394 11.49 4265.418 O.I 1 1 I.I88 1-295 12.92 0.071 0.758 0.839 12.07 0.031 0-334 0.382 11.14 4266.081 0. 112 I.I97 1.304 13.01 0.071 0.758 0.839 12.07 0.032 0-344 0.392 "43 4268.915 O.II3 1. 206 I.3I3 13.10 0.070 0.747 0.828 11.91 0.030 0.322 0.370 10.79 4276.836 O.I 1 1 I.I83 1.290 12.87 0.072 0.768 0.849 12.21 0.030 0.321 0.369 10.76 4283.169 O.II2 I.igi 1.298 12-95 0.070 0-745 0.826 11.88 0.029 0.310 0.358 10.44 4284.838 O.III I.lSo 1.287 12.84 0.070 0-745 0.826 11.88 0.032 0-341 0.389 n-34 4287.566 O.II4 1. 212 1.319 13.16 0.071 0-755 0.836 I2.O2 0.030 0.321 0.369 10.76 4288.310 O.II3 I.2OI 1.308 13.04 0.072 0.765 0.846 12.17 0.032 0.341 0.389 II-34 4289.525 O.II2 I.I9I 1.298 12-95 0.071 0-755 0.836 I2.O2 0.030 0.320 0.368 10.73 4290.377 O.I 1 2 I.I90 1.297 12.94 0.073 0.776 0.857 12.32 0.030 0.320 0.368 10-73 4290.542 O.II4 1. 211 1-318 I3-I5 0.071 0-754 0-835 I2.OI 0.031 0-330 0.378 11.02 4291.630 O.II4 1. 211 1.318 I3-I5 0.072 0.764 0.845 12.15 0.031 0.330 0.378 1 1. 02 RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908. 75 TABLE n. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908 Continued. Plate w 117.,. 1908, May 26, I2 h o nl G. M. T. Measured by L. on T. Distance from Limb 1.6 mm. Quality, good. P-P O o-n p D 6S-3 350-8 17.4 i.i Diameter 168.7 torn Factor 1.019 0.6 14.1 14.1 7S-9 4-7 .003 29.6 29.6 60.4 2-3 .001 45-4 45-4 44.6 1.6 .OOO 60.6 60.6 29.4 1.4 .OOO 75-6 75-6 14.4 1.2 .000 90.6 0.6 -0.6 I.I .OOO = ' - o6 = 14^4 = 2Q?4 X A V + , i A V V + D, f A t> + , i. km km km km km km 4196.699 0.174 1.898 2.032 14-43 O.I 60 1-745 1.878 13-77 0.138 .506 1.631 13-30 4197.257 0.173 1.887 2.021 14.36 o.i 60 1-745 1.878 13-77 0.138 .506 1.631 13-30 4203.730 0.176 I-9I5 2.049 14-51 0.162 1.760 I-893 13.88 0.142 541 1.666 13-58 4207.566 0.177 1.924 2.058 14.61 0.162 I.7S8 1.891 13.86 0.141 530 1-655 13-49 4216.136 0.175 1.898 2.032 14-43 0.162 1-757 1.890 13.86 0.140 519 1.644 13.40 4220.509 0.176 1.907 2.041 14.49 0.162 1-755 1.888 13-84 0.142 1-538 1.663 13-56 4232.887 0.180 1.942 2.076 14.74 0.162 1-748 i. 88 1 13-79 0.143 1-544 1.669 13.61 4233-328 0.178 1.920 2.054 14.58 0.164 1.768 1.901 13-94 0.142 1-532 I-657 13-51 4257.815 0.180 1.929 2.063 14.65 0.165 1.768 I.QOI 13-94 0.144 1-538 1.663 13-56 4258.477 0.180 1.928 2.062 14.64 0.163 1-747 1. 880 13-78 0.144 J-537 1.662 13-55 4265.418 0.180 1.924 2.058 14.61 0.164 J-753 1.886 13-83 0.144 I-536 1.661 13-54 4266.081 0.181 1-934 2.068 14.69 o.i 66 1.769 1.902 13-94 0.144 1-535 i. 660 13-53 4268.915 0.181 1-933 2.067 14.68 0.167 1-783 1.916 14.05 0.145 1-545 1.670 13.61 4276.836 0.181 1.929 2.063 14.65 0.168 1.790 1.923 14.10 0.145 i -544 1.669 13.61 4283.169 0.182 1.936 2.070 14.70 o.i 66 1-765 1.898 13-91 o.!44 1-532 1-657 13-51 4284.838 0.182 1.936 2.070 14.70 0.168 1.786 1.919 14.07 0-143 521 1.646 13-42 4287.566 0.180 I-9I3 2.047 J4-54 0.165 I-756 1.889 13-85 0.145 543 1.668 13.60 4288.310 0.182 1-935 2.069 14.69 0.167 1.777 1.910 14.00 0.147 -564 1.689 13-77 4289.525 0.182 1-934 2.068 14.69 0.168 1.786 1.919 14.07 0.146 552 1.677 13-67 4290.377 0.182 1-933 2.067 14.68 o.i 66 1.764 1.897 13-91 0.145 541 1.666 13-58 4290.542 0.180 1.922 2.056 14.60 o.i 68 1.784 1.917 14.05 0.149 .582 1.707 13-91 4291.630 0.183 1.942 2.076 14-74 0.166 1.764 1.897 13-91 0.148 572 1.697 13-83 (f> = 44.6 = 6o!4 = 7S.9 4196.699 0.108 .180 .287 12.84 0.069 0-753 0.834 11.99 0.029 0.317 0-365 10.64 4197.257 0.108 .181 .288 12.85 0.068 0.742 0.823 11.84 0.030 0.327 0-375 10.93 4203.730 O.IIO '93 .300 12.97 0.070 0.762 0.843 12.12 0.029 0.317 0-365 10.64 4207.566 0.109 .183 .290 12.87 0.068 0-739 0.820 11.79 0.031 0-335 0-383 ii. 16 4216.136 0.108 .172 .279 12.76 0.066 0.722 0.803 ii-SS 0.030 0-325 0-372 10.84 4220.509 O.IIO .190 .297 12.94 0.069 0.748 0.829 11.92 0.030 0.325 0-372 10.84 4232-887 0.109 177 .284 12.81 0.071 0.767 0.848 12.19 0.031 0-334 0.382 11.13 4233-328 O.IIO .187 .294 12.91 0.070 0.756 0.837 12.04 0.029 0.314 0.362 10.55 4257-8IS O.III .189 .296 12.93 0.074 0.791 0.872 12.54 0.032 0-344 0-392 "43 4258.477 O.III .188 295 12.92 0.072 0.770 0.851 12.24 0.032 0-343 0.391 "39 4265.418 O.IIO .178 -285 12.82 0.071 0.760 0.841 12.09 0.031 0-333 0.381 II. IO 4266.081 O.II2 1.194 .301 12.98 0.072 0.769 0.850 12.22 0.032 0-343 0.391 "39 4268.915 O.II2 I-I93 300 12.97 0.072 0.768 0.849 12.21 0.032 0-343 o.39i "39 4276.836 O.II2 I-I93 .300 12.97 0.071 0.758 0.839 I2.O7 0.032 0.342 0.390 "37 4283.169 O.III 1.181 .288 12.85 0.072 0.770 0.851 12.24 0.032 0.342 0.390 "37 4284.838 O.I 1 2 1.194 .301 12.98 0.072 0.769 0.850 12.22 0.032 0-344 0.392 "43 4287.566 O.II2 I-I93 .300 12-97 0.073 0.779 0.860 12.36 0.033 0-354 0.402 11.72 4288.310 O.II3 1.203 .310 13-07 0.073 0-777 0.858 12-33 0.032 0-343 0-391 "39 4289.525 O.I 1 2 1.191 .298 12.95 0.073 0.777 0.858 12-33 0.033 0-353 0.401 11.69 4290.377 O.II4 1. 211 .318 I3-I5 0.072 0.767 0.848 12.19 0.032 0-343 0.391 "39 4290.542 O.II4 1. 211 -3l8 13-15 0.073 0.776 0-857 12.32 0.032 0-343 0-391 n-39 4291.630 O.II3 I.2OO 307 13-04 0.074 0.786 0.867 12.47 0-033 0-352 0.400 11.66 76 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE n. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908 Continued. Plate w I20j. 1908, June 2, 3 h io m G. M. T. Measured by L. on T. Distance from Limb 1.2 mm. Quality, good. p P T T] Q 71-7 12.7 12.7 77-3 1.6 i.ooo 0-0 357.2 26.2 26.2 63.8 0.8 1. 000 P 15-0 41.7 41.7 48.3 o-S I.OOO D -0.3 57-2 57-2 32.8 0.4 I.OOO Diameter 168.0 mm 72.7 72.7 17-3 0.4 I.OOO Factor 1.014 87.7 87.7 2-3 0.4 I.OOO 102.7 102.7 -12.7 0.4 I.OOO --.* = 2?3 = i??3 A ' ti + j I A V . + A 11 V -f- V f 4196.699 o.i 66 km .802 km 1.932 14.06 0.175 km 1.894 km 2.028 14.41 0.158 km 715 km 1.846 13-74 4197-257 o.i 66 .801 931 14.05 0.176 1.904 2.038 14.48 0.158 .715 1.846 13-74 4203.730 o.i 66 .798 .928 14-03 0.175 1.893 2.027 14.40 0.161 739 1.870 I3-92 4207.566 0.169 .825 955 14-23 0.175 1.893 2.027 14.40 0.160 .728 1.859 13.84 4216.136 o.i 68 .813 943 14.14 0.176 1.899 2-033 14.44 0.160 .726 1-857 13.82 4220.509 0.170 .832 .962 14.28 0.178 1.918 2.052 14.58 0.161 735 1.866 13.89 4232.887 0.170 .825 955 14-23 0.180 1.932 2.066 14.67 0.162 .740 1.871 13-93 4233-328 0.170 .825 955 14-23 0.180 I-93I 2.065 14.67 0.164 759 1.890 14.07 4257-815 0.173 .841 .971 14-34 0.180 1.912 2.046 14-54 0.162 724 1.855 13.80 4258.477 0-173 .841 97i 14-34 0.182 I-93I 2.065 14.67 0.162 724 1.855 13.80 4265.418 0.172 .829 959 14.26 0.182 1.930 2.064 14.66 0.163 733 1.864 13.88 4266.081 0.173 .841 .971 14-34 0.182 1.928 2.062 14.65 0.160 .701 1.832 13.64 4268.915 0.174 .850 .980 14.41 0.180 1.909 2.043 14.51 0.164 739 1.870 13.92 4276.836 0.169 793 923 13-99 0.180 1.908 2.042 I4-5I 0.165 1.746 1.877 13-97 4283.169 0.173 830 .960 14.26 0.182 1.927 2.061 14.64 0.164 I-736 1.867 13.90 4284.838 0-173 830 .960 14.26 0.182 I-925 2.059 14-63 0.164 1-734 1.865 13.88 4287.566 0.173 .829 959 14.26 0.182 I-925 2.059 14.63 0.164 734 1.865 13.88 4288.310 0.174 843 973 14-36 0.183 J-935 2.069 14.70 0.165 743 1.874 13-95 4289.525 0.174 .841 .971 14-34 0.182 1.923 2.057 14.62 0.165 .742 1-873 13-94 4290-377 0-173 830 .960 14.26 0.184 1-943 2.077 14.76 0.164 732 1.863 13-87 4290.542 0.176 .860 .990 14.48 0.183 J-933 2.067 14.69 0.164 732 1.863 13-87 4291.630 0.176 .860 .990 14.48 0.182 1.923 2.057 14.62 0.162 .712 1.843 I3-72 = 32.& 0=48!3 = 63^8 = 7?!3 _ A D .+,, f A V , + ,, 1 A > + , * A ' . + ,, 4196.699 0.139 km 1.499 km 1.618 o 13-67 0.096 km 1.042 km 143 12.20 0.051 km 0-555 km 0.628 IO.IO 0.026 km 0.282 km 0.32; 10.56 4I97-257 0.138 1.498 1.617 13.66 0.096 .042 143 12.20 0-053 0-575 0.648 10.42 0.026 0.282 0.323 10.56 4203.730 0.140 1.516 1-635 13.81 0.098 .061 .162 12.40 0.052 0-563 0.636 10.23 0.027 0.292 0-335 10.88 4207.566 0.141 1.521 1.640 13-85 0.098 .061 .16: I2.4O 0.052 0.562 0.635 IO.2I 0.027 0.291 10.85 4216.136 0.139 1.501 1.620 13-68 0.098 057 IS* 12.36 0.052 0.561 0.634 IO.2O 0.026 0.280 0-325 10.50 4220.509 0.141 1.520 1.639 13.84 0.102 .099 .2OC 12.81 0-053 0.570 0-643 10-34 0.025 0.270 0-315 10.17 4232.887 0.142 1-524 1.643 13.88 O.IOO 073 .174 12.5.3 0-053 0.569 0.642 10-33 0.028 0.300 0-345 11.14 4233-328 0.142 I-S24 1-643 13-88 O.IOO 073 .174 12-53 0.053 0-569 0.642 10-33 0.028 0.300 0-345 11.14 4257-815 0.144 1-535 1.654 13-97 O.IOI 075 .176 12-55 0-053 0-565 0.638 IO.26 0.028 0.297 0.342 11.04 4258.477 0.142 1.511 1.630 13-77 0.102 -085 .l8 12.66 0.052 0-555 0.638 10.26 0.027 0.287 0-332 10.72 4265.418 0.143 1.521 1.640 13-85 O.IOO 1.064 1.165 12.43 0.054 0-574 0.647 10.41 0.028 0.297 0.342 11.04 4266.081 0.144 I-525 1.644 13.89 0.103 1.095 I.I9 1) 10.7 10.7 79-3 1.6 .000 Q 71.7 24.2 24.2 65.8 0.8 .000 o-n 357.2 39-7 39-7 50.3 0-5 .000 P 15-0 5S-2 55-2 34-8 0.4 .000 D -0.3 70.7 70.7 19-3 0.4 .000 Diameter 168.0 mm 85.7 4-3 o-4 .000 Factor 1.014 100.7 100.7 -10.7 0.4 .000 \ *--* *-A 4> = I9?3 A A ' f + ! A t> f + , A D .+,, 1 4196.699 0.170 km 1.844 km 1-974 14.26 0.175 km .900 km 2.034 14.48 0.156 km 693 km 1.824 13-74 4197-257 0.170 1-844 1-974 14.26 0.176 .910 2.044 14-56 0.156 693 1.824 13-74 4203.730 0.172 1.862 1.992 14-39 0.177 .916 2.050 14.60 0.159 .722 I-853 13.96 4207.566 0.173 1.872 2.002 14.46 0.176 .904 2.038 14-51 o.i 60 731 1.862 14.02 4216.136 0.174 1.877 2.007 14-50 0.174 .878 2.OI2 14-33 0.157 693 1.824 13-74 4220.509 0.176 I-897 2.O27 14-64 o.i So .940 2.074 14-77 o.i 60 .719 1.850 13-93 4232.887 0.176 1.888 2.018 14-58 0.178 .910 2.044 14-56 0.159 707 1.838 13-84 4233-328 0.174 1.867 1.997 14-43 0.178 .910 2.044 14-56 o.i 60 717 1.848 13-92 4257-815 0.177 1.887 2.017 14-57 0.181 .918 2.052 14.61 0.161 .708 1.839 13-85 4258.477 0.176 1.876 2.OO6 14.49 0.180 .908 2.042 14-54 0.161 .707 1.838 13.84 4265.418 0.177 1.887 2.OI7 14.57 0.180 .904 2.038 14-51 o.i 60 697 1.828 13-77 4266.081 0.177 1.886 2.016 14.56 0.181 .916 2.050 14.60 0.162 .716 1.847 13-91 4268.915 0.178 1.896 2.026 14.64 0.180 .906 2.040 14-53 0.162 715 1.846 13.90 4276.836 0.176 1.867 1.997 14-43 0.180 905 2.039 14-52 o.i 60 .694 1.825 13-75 4283.169 0.178 1.884 2.OI4 14-55 0.180 904 2.038 14-51 0.162 715 1.846 13.90 4284.838 0.179 1.894 2.024 14.62 0.181 .916 2.050 14.60 0.161 .704 1.835 13.82 4287.566 0.176 1.862 1-992 14-39 0.180 .904 2.038 14-51 0.162 .714 1-845 13-90 4288.310 0.179 1.893 2.023 14.62 0.180 903 2.037 14.50 0.163 .724 1.855 13-97 4289.525 0.178 1.882 2.OI2 14-54 0.180 .902 2.036 14-50 o.i 60 693 1.824 13-74 4290.377 0.178 1.882 2.012 14.54 0.179 .892 2.026 14-43 0.161 .704 1-835 13.82 4290.542 0.179 1.891 2.O2I 14.60 0.182 .922 2.056 14.64 0.163 .724 1.855 13-97 4291.630 0.179 1.891 2.O2I 14.60 0.180 .901 2-035 14.49 0.162 712 1.843 13-88 0=34:8 .=50:3 *-6 S : 8 = 79?3 A V t> + z>i A 11 f + t>, A V , + ,, A V . + ,, km km km km km km o km km 4196.699 0.136 1-475 1-594 13.78 0.095 1.030 I.I28 12.54 0.057 O.62I 0.68? "93 0.019 0.206 0-245 9-37 4197-257 0.136 1.476 1-595 13-79 0.096 1.039 I-I37 12.64 0.058 0.630 0.698 12.09 0.019 0.206 0-245 9-37 4203.730 0.138 1.490 1. 60? 13-91 0.098 1.062 l.IOC 12.89 0.058 0.626 0.694 12.02 O.O2O 0.216 0-255 9-75 4207.566 0.138 1.488 1.605 13.89 0.098 1.061 1.159 12.88 0.058 0.626 0.694 12. 02 0.020 0.215 0.254 9.71 4216.136 0.136 1.467 1.58^ 53.71 0.097 1.044 1.142 12.69 0.058 0.625 0.693 I2.OO O.O2O 0.215 0.254 9.71 4220.509 0.139 1-493 1.61; 13-94 0.099 1.065 1.163 12.93 0.058 0.625 0.693 I2.OO O.O2O 0.215 0.254 9.71 4232.887 0.140 1.502 1.621 14.01 0.099 1.063 1.161 12.90 0.058 0.623 0.691 11.97 0.020 0.215 0.254 9-71 4233-328 0.140 1.502 .621 14.01 0.098 1.052 1.150 12.78 0.056 0.601 0.669 "59 0.019 0.204 0.243 9.29 4257-815 0.142 1-505 .624 14.04 O.IOO 1.067 1.165 12-95 0.060 0.639 0.707 12.24 O.O22 0.234 0-273 10.44 4258.477 0.140 1.483 .605 13-85 O.IOO 1.066 1.164 12.94 0.060 0.639 0.707 12.24 O.O2O 0.213 0.252 9.64 4265.418 0.141 1.492 .611 13-93 O.IOI 1.071 i.i6c 12.99 0.059 0.628 0.696 12.05 0.021 0.223 0.262 IO.O2 4266.081 0.141 1-492 .611 13-93 O.IOI 1.071 1.169 12-99 0.060 0-635 0.703 12. l8 O.O2O 0.213 0.252 9.64 4268.915 0.140 1.482 .601 13.84 0.099 1-053 1.151 12.79 0.060 0.635 0.703 12. l8 O.O2O O.2I2 0.251 9.60 4276.836 0.142 I-503 .622 14.02 O.IOO 1-059 i-i57 12.86 0.060 0.635 0-703 12.18 0.021 0.223 0.262 IO.O2 4283.169 0.140 1.481 .6oc 13-83 O.IOO 1.059 I-I57 12.86 0-057 0-593 0.661 "45 0.020 0.212 0.251 9-6o 4284.838 0.142 I-504 .623 14-03 O.IO2 1.079 1.177 13.08 0.059 0.625 0.693 I2.OO O.O2O O.2II 0.250 9.56 4287.566 0.141 1.492 .611 13-93 O.IOO 1.058 1.156 12.85 0.060 0.635 0.703 12.18 0.022 0.232 0.271 10.36 4288.310 0.142 1.502 .621 14.01 O.IO2 1.078 1.176 13-07 0.059 0.624 0.692 11.98 0.024 0-253 0.292 ii. 16 4289.525 0.141 1.491 .6ic 13.92 O.1O2 1.078 1.176 13-07 0.059 0.624 0.692 11.98 O.O24 0-253 0.292 u. 16 4290.377 0.140 1.480 1-599 13.82 O.IOI 1.067 1.165 12.95 0.058 0.615 0.683 11.83 0.022 0.232 0.271 10.36 4290.542 0.142 1.500 1.619 14.00 O.IOI 1.067 1.165 12.95 0.059 0.624 0.692 12.98 0.020 0.21 1 0.250 9-56 4291.630 0.142 1.500 1.619 14.00 O.IOO 1-057 12.84 0.062 0.616 0.684 11.83 O.O22 0.232 0.271 10.36 78 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE u. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908 Continued. Plate w I28 r 1908, June 9, I2 h 50 G. M. T. Measured by L. on T. Distance from Limb 1.5 mm. Quality, good. p-f Q Q-a p D 78.7 4-2 12. 1 0.6 Diameter 166.0 mm Factor 1.018 0.5 15-5 iS-5 74-5 2.O I.OOI 30-5 30-S 59-5 I.O I.OOO 45-5 45-5 44-S 0.7 1. 000 60.5 60.5 29-S 0.6 i.ooo 75-5 75-5 14-5 0.6 I.OOO 90-5 9-5 -o-S 0.6 I.OOO = -o!s = u:s = 29 !5 A .-M, i A t> +, A V . + ., i 4196.699 0.174 km 1.897 km 2.031 14.42 0.164 km 1.787 km .917 14.06 0.143 km 1.560 km 1.684 13-74 4197-257 0.174 .896 2.030 14.41 0.162 1.776 .906 13.98 0.144 1.569 1.693 13.81 4203-730 0.176 .914 2.048 14-54 0.164 1.778 .908 13-99 0.144 I-556 1. 680 13-70 4207-566 0.177 923 2.057 14.61 0.163 1.768 .898 13.92 0-145 1.565 1.689 13-76 4216.136 0.175 .896 2.030 14.41 0.162 1-757 .887 13.84 0.145 I-565 1.689 13-76 4220.509 0.177 .910 2.044 14-51 0.165 1.782 .912 14.02 0.144 1-554 1.678 13-70 4232.887 0.177 .907 2.041 14.49 0.166 1.787 .917 14.06 0.145 1.564 1.688 13-78 4233-328 0.178 .918 2.052 14-57 0.166 1.787 .917 14.06 0.146 1-573 1.697 13-85 4257-8I5 0.182 949 2-083 14.79 o.i 68 1-795 925 14.12 0.148 1-574 1.698 13-85 4258.477 0.181 935 2.069 14.69 0.169 i. 808 938 14.21 0.146 1-554 1.678 13-70 4265.418 o.i 80 923 2-057 14.61 0.167 1-777 .907 13.98 0.146 1-553 1.677 13.69 4266.081 0.182 943 2.077 14-75 o.i 68 1.787 .917 14.06 0.147 1.564 1.688 13.78 4268.915 0.181 929 2.063 14-65 0.167 1.779 .909 14.00 0.146 '553 1.677 13.69 4276.836 0.181 .928 2.062 14.64 0.167 1-779 .909 14.00 0.146 1-552 1.676 13.68 4283.169 0.183 945 2.079 14.76 0.170 1.810 940 14-23 0.147 1.562 1.686 13-75 4284.838 0.182 933 2.067 14.68 o.i 68 1.784 .914 14.04 0.146 1-550 1.674 13-67 4287.566 0.180 .912 2.046 14-50 0.169 1.794 .924 14.11 0.147 1.560 1.684 13-75 4288.310 0.181 923 2.057 14.61 0.169 1-794 .924 14.11 0.148 i-S7o 1.694 13-83 4289.525 0.182 932 2.066 14.67 o.i 68 1-783 913 14-03 0.148 J-570 1.694 13-83 4290.377 0.181 .921 2-055 14-59 0.170 1.805 935 14.19 0.146 1-549 1-673 13-65 4290.542 0.182 1-93' 2.065 14.66 0.169 1-793 923 14.10 0.151 i. 60 1 1-725 14.08 4291-630 0.182 I-93I 2.065 14.66 0.169 1-793 1.923 14.10 0.149 1.581 1-705 13-91 = 44?S = S9?5 = 74!5 4196-699 0.105 1.146 .252 12.46 0.070 0.763 0.845 11.82 0.030 0.327 0-379 10.07 4197-257 o.i 06 1.155 .261 12.55 0.068 0.741 0.823 11.51 0.028 0.306 0.358 9-51 4203.730 0.108 1.171 .277 12.71 0.070 0.762 0.844 11.81 0.030 0.326 0-378 10.04 4207.566 0.108 1.171 277 12.71 0.070 0.760 0.842 11.78 0.030 0.326 0-378 10.04 4216.136 o.i 06 1.149 255 12.49 0.068 0-737 0.819 "45 0.029 0.314 0.366 9.72 4220.509 0.108 1.166 1.272 12.66 0.070 0-758 0.840 "75 0.030 0.325 0-377 IO.O2 4232.887 0.108 1.163 1.269 12.62 0.068 0-733 0.815 11.40 0.031 0-334 0.386 IO.25 4233-328 0.107 I-I53 1-259 12-53 0.068 0-733 0.815 11.40 0.030 0.323 0-375 9.96 4257.8I5 O.IIO 1.171 1.277 12.71 0.072 0.770 0.852 11.92 0.031 0-332 0.384 IO.2O 4258.477 0.108 1.151 1-257 12.51 0.071 0.760 0.842 11.78 0.032 0-342 0-394 10-47 4265.418 0.108 1.151 1-257 12.51 0.069 0-737 0.819 n-45 0.031 0-331 0-383 10.17 4266.081 0.109 1.161 .267 12. 6l 0.072 0-755 0.837 11.71 0.031 0-33' 0-383 10.17 4268.915 0.107 1-139 245 12.39 0.072 0-755 0.837 11.71 0.030 0.320 0.372 9.88 4276.836 0.108 1.148 254 12.48 0.070 0-745 0.827 "57 0.032 0-340 0.392 10.41 4283.169 0.108 1.148 254 12.48 0.070 0-745 0.827 "57 0.031 0.329 0.381 IO.I2 4284.838 0.109 1.158 .264 12.58 0.069 0.736 0.818 11.44 0.030 0.319 0.371 9-86 4287.566 0.107 I-I39 245 12.39 0.070 0-745 0.827 n-57 0.031 0.329 0.381 IO.I2 4288.310 o.i 08 1.148 -254 12.48 0.072 0.765 0.847 11.85 0.030 0.319 0.371 9.86 4289.525 0.108 1.147 253 12.47 0.070 0-745 0.827 11-57 0.031 0.329 0.381 IO.I2 4290-377 0.108 1.147 253 12.47 0.069 0-735 0.817 "43 0.030 0.319 0.371 9-86 4290.542 0.109 1.156 .262 12.56 0.070 0-745 0.827 "57 0.032 o-339 0-391 10.39 4291.630 0.109 1.156 .262 12.56 0.073 0-775 0.857 11.97 0.034 0.361 0-413 10.97 RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908. 79 TABLE n. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908 Continued. Plate w 132. 1908, June 10, 8 h 15 G .M. T. Measured by L. on T. Distance from Limb, 1.4 mm. Quality, good. sec') 0.6 O 79-5 10.6 10.6 79-4 3-4 i. 002 O-n 5.0 25.6 25.6 64.4 i-5 I.OOO P 11. 7 40.6 40.6 49-4 I.O I.OOO D 0.7 55-6 55-6 34-4 0.8 I.OOO Diameter 165.6 mm 70.6 70.6 19.4 0.6 I.OOO Factor 1.017 85.6 85.6 4-4 0.6 i.ooo = 4?4 - IQ?4 = 34?4 X A V + ! 1 A V t + , A V + [ f km km o km km km km 4196.699 0.172 1.873 2.007 14.29 0.162 1.764 1.895 14.26 0-135 .469 1-588 13-66 4 I 97- 2 S7 0.172 1.873 2.007 14.29 0.161 1-753 .884 14.18 0.134 459 1-578 13-58 4203.730 0.176 1.912 2.046 14-57 0.163 1.766 .89? 14.28 0.138 500 1.619 13-93 4207.566 0.174 1.888 2.O22 14.40 0.162 1-755 .886 14.20 0.138 497 .616 13-91 4216.136 0.174 1.883 2.OI7 14.36 0.161 1-743 .874 14.10 0-137 485 .604 13.80 4220.509 0.176 1.903 2.037 14-5 0.164 1-773 .904 14-34 0-137 .481 .600 13-77 4232.887 0.178 1.916 2.050 14.60 0.164 1-765 .896 14.27 0.136 465 584 13-63 4233-328 0.178 1.916 2.050 14.60 0.164 1-765 .896 14.27 0-137 475 594 13.72 42S7-8IS 0.177 1.893 2.O27 14-43 0.167 1-785 .916 14.42 0.138 .476 595 13-73 4258-477 0.179 1.912 2.046 14-57 o.i 66 1-775 .006 14-34 0.138 473 592 13-7 4265.418 0.179 1.910 2.044 14.56 o.i 66 1.770 .901 14-31 0.138 .468 587 13.66 4266.081 O.I 80 1.920 2.054 14.63 o.i 66 1.770 .901 14-31 0.140 493 .612 J3-87 4268.915 O.I 80 1.912 2.046 14-57 0.165 1.760 .891 14-23 0.138 .467 .586 13-65 4276.836 0.180 1.912 2.046 14-57 0.167 1-774 90S 14-35 0.138 .466 585 13-63 4283.169 0.179 i. goo 2-034 14.48 0.167 1-773 .904 14-34 0.139 .476 595 13-73 4284.838 0.178 1.890 2.O24 14.41 o.i 66 1.762 893 14-25 0-139 475 594 I3-72 4287.566 0.177 1.878 2.OI2 I4-32 0.167 1.771 .902 14-32 0.138 .464 .583 13.62 4288.310 0.178 1.888 2.022 14.40 0.165 750 .881 14.17 0.139 475 -594 13.72 4289-325 0.180 1.908 2.O42 14-55 0.167 .772 93 J4-33 0.137 453 572 13-53 4290.377 0.178 1.887 2.O2I 14-39 0.167 .770 .901 14-31 0.139 475 594 I3-72 4290.542 0.180 1.908 2.O42 14-55 0.167 .770 .901 14-31 0.142 505 .624 13.98 4291.630 0.177 1.876 2.0IO I4-3I 0.168 .780 .911 14.38 0.141 495 .614 13.89 0- 49?4 = 64^4 <(> = 7Q?4 4196.699 0.097 .056 .1* 12.00 0.060 0.651 0.723 11.88 O.020 0.218 0.258 9.96 4I97-2S7 0.097 .056 155 12. 6O 0.058 0.631 0.703 11.56 O.O2O 0.218 0.258 9.96 4203.730 O.IOO .086 .I8 S 12.93 0.060 0.651 0.723 11.88 O.O2O 0.217 0.257 9.92 4207.566 0.098 .062 .l6l 12.67 0.060 0.650 0.722 11.87 0.020 0.217 0.257 9.92 4216.136 0.098 .061 .160 12.66 0.060 0.649 0.721 11.84 O.Olg 0.208 0.248 9-57 4220.509 0.099 .068 .167 12.73 0.058 0.627 0.699 11.50 O.O2O 0.217 0.257 9-92 4232.887 O.IOO .076 175 12.82 0.060 0.646 0.718 11.80 0.020 0.216 0.256 9.88 4233-328 O.IOO .076 175 12.82 0.060 0.646 0.718 11.80 O.O2I 0.226 0.266 10.27 4257-815 0.099 .056 155 12.60 0.06 1 0.652 0.724 11.90 O.O22 0.234 0.274 10.57 4258.477 0.099 056 155 12.60 0.060 0.638 0.710 11.68 O.O2I 0.224 0.264 10.19 4265.418 O.IOO .063 .162 12.68 0.060 0.638 0.710 11.68 0.020 0.214 0.254 9.80 4266.081 O.IOI 073 .172 12.79 0.059 0.630 0.702 "54 O.O22 0.234 0.274 10.57 4268.915 O.IOI 73 .172 12.79 0.062 0.659 0.731 I2.O2 0.022 0.234 0.274 10.57 4276.836 0.099 054 153 12.58 0.060 0.638 0.710 n.68 0.021 0.224 0.264 10.19 4283.169 O.IOO .062 .l8l 12.89 0.060 0.638 0.710 11.68 O.O2I 0.224 0.264 10.19 4284-838 O.IO2 .083 .182 12.90 0.060 0.638 0.710 11.68 O.O2I 0.224 0.264 10.19 4287.566 O.IOO .061 .160 12.66 0.060 0.638 0.710 11.68 O.O22 0.234 0.274 10.57 4288.310 O.IO2 .083 .182 12.90 0.06 1 0.648 0.720 11.83 O.O2I 0.224 0.264 10.19 4289.525 0.103 93 .192 13.00 0.062 0.657 0.729 11.98 O.O2O 0.214 0.254 9.80 4290.377 O.IOO i. 060 ' -159 12.65 0.060 0.637 0.709 11.66 0.020 0.214 0-254 9.80 4290.542 O.IOI 1.070 .169 12.76 0.060 0.637 0.709 11.66 O.O2I 0.223 0.263 10.15 4291.630 0.102 1.081 .ISO 12.88 0.06 1 0.647 0.719 11.82 O.O22 0-233 0.273 10.54 8o AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. n. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS or 1908 Continued. [Plate w 134. 1908, June u, 3 h o m G. M. T. Measured by L. on T. Distance from Limb 2.5 mm. Quality, good. P-P secy O o-n p D 80.2 5-7 11.4 0.8 Diameter 168.0 mm Factor 1.031 o-5 10.5 2S-S 10.5 25-5 79-5 64-S 4.0 i-7 1. 002 I.OOO 40.5 40.5 49-5 i.i 1. 000 55-5 55-5 34-S o-9 I.OOO 70.5 85-5 70.5 85.5 I9-S 4-5 0.7 0.7 I.OOO I.OOO 9-5 Qo-S -o-5 0.7 I.OOO = .S = 4.$ = IQ?5 A ii !) + !), A t 11 + II, A n V + Zlj I f km km km km km km 4196.699 0.171 1.888 2. 022 14-36 0.169 1.864 1.998 14-23 0.156 .721 1.852 13-95 4197-257 0.172 1.897 2.031 14.42 0.169 1.864 1.998 14-23 0.156 .721 1.852 13-95 4203.730 0.174 1.914 2.048 14-54 0.170 1.870 2.004 14.27 0.157 .727 1.858 13-99 4207.566 0.173 1.900 2-034 14-45 0.173 1.902 2.036 14.5 0.158 737 1.868 14.07 4216.136 0.174 1.907 2.O4I 14.49 0.169 1-855 1.989 14.16 0.156 .711 1.842 13-87 4220.509 0.174 1.905 2.039 14.48 0.172 1.883 2.017 14.36 o.i 60 752 1.883 14 18 4232-887 0.176 1.918 2.052 14-57 0.174 I-OOS 2.039 14.52 o.i 60 745 1.876 14-13 4233-328 0.175 1.908 2.O42 14-50 0.174 1.905 2-039 14.52 0.161 -756 1.887 14.21 4257-815 0.178 1.929 2.063 14-65 0.173 1.875 2.009 14-31 0.161 745 1.876 14.13 4258.477 0.177 1.914 2.048 14-54 0.174 1.885 2.019 14.38 o.i 60 735 1.866 14.05 4265.418 0.177 1.912 2.046 14-53 0-175 1.891 2.025 14.42 0.160 731 1.862 14.02 4266.081 0.178 1.918 2.052 14-57 0.175 1.891 2.025 14.42 o.i 60 731 1.862 14.02 4268.915 0.178 1.926 2.060 14.63 0.175 1.889 2.023 14.41 o.i 60 730 i. 86 1 14.01 4276.836 0.179 1.916 2.050 14-55 0.174 1-875 2.009 14.31 0.161 737 1.868 14.06 4283.169 0.178 1.914 2.048 H-54 0.174 1.871 2.005 14.28 0.158 699 1.830 13-78 4284.838 O.I 80 1-932 2.O66 14.67 0.175 1. 880 2.014 14.34 o.i 60 .721 1.852 13-95 4287.566 0.178 ' 1.912 2.046 14.53 0.175 1.880 2.014 14-34 0.160 .721 1.852 13-95 4288.310 0.177 1.903 2-037 14-47 0.174 1.870 2.004 14.27 0-159 .709 1.840 13.86 4289.525 0.177 1.902 2-036 14.46 0.175 1.880 2.014 14-34 0.161 i-73i 1.862 14.02 4290.377 0.177 1.902 2.036 14.46 0.171 1.869 2.003 14.26 0-159 1.708 1.839 13-85 4290.542 0.177 1.902 2.036 14.46 0-173 1.858 1.992 14.19 0.162 1-739 1.870 14.08 4291.630 0.176 1.891 2.025 14.38 0.175 1.878 2.OI2 14-33 0.161 1.728 1.859 14.00 \ = 34.S = 49.S = &4!S = 7Q?5 A A D * + , A 2 ZI + D! A t * + tl, 1 A t; + j km km km km km km km km 4196.699 0.130 435 1-555 13.40 0.096 1.058 I-I57 12.65 0.057 0.629 0.701 11.56 0.019 O.2IO 0.250, 9.74 4197.257 0.131 445 1.66; 13.48 0.096 1.058 I-I57 12.65 O.O58 0.619 0.691 11.40 0.022 0.242 0.282J 10.99 4203.730 0.132 453 i-57; 13-55 0.096 1.056 I-I55 12.63 0.057 0.627 0.690 11.51 0.020 0.220 0.260 > 10.13 4207.566 0.130 .430 i-55< ' 13-35 0.097 1. 066 1.165 12.74 0.058 0.638 0.710 11.72 O.O2O O.22O O.2&C > 10.13 4216.136 0.132 .446 i-56( 13-49 0.097 1.063 1.162 12.70 0.057 0.625 0.695 11.50 O.OI9 O.2O9 0.240 ) 9-70 4220.509 0.131 435 1-55; 13.40 O.IOO 1.096 I-I95 13.06 0.058 0.634 0.70^ 11.64 O.O2O 0.219 0.851 ) 10.09 4232.887 0.132 440 1.560 > 13-44 0.098 1. 068 1.167 12.76 0.058 0-633 0.70; 11.62 0.019 0.208 0.24; ! 9.66 4233-328 0.132 440 1.560 > 13-44 0.098 1. 068 1.16; 12.76 0.058 0.633 0.70; 11.62 O.OI9 O.2O8 0.24! ! 9.66 4257-815 0-133 443 1-56; 13-47 O.IOO 1.085 1.184 12.94 0.059 0.639 0.711 "73 O.O2O 0.217 0.25- ' 10.01 4258.477 0-133 .441 1.561 13-45 0.099 1.071 1.170 I 2. 80 0.059 0.639 0.711 "73 0.021 0.227 0.26- 10.40 4265.418 0.132 .428 i-54i 13-34 0.099 1.071 1.170 12. 80 0.060 0.649 0.721 11.89 O.O22 0.237 0.27- 10.79 4266.081 0.134 .448 1.56! ! 13-51 0.098 1.059 l.lgt 12.66 O.o6o 0.649 0.721 11.89 O.O22 0.237 0.27- 10.79 4268.915 0.132 425 i-54. 13-31 0.098 1.056 I-I55 12.63 O.O6O 0.649 0.721 11.89 O.O2O 0.216 0.25* > 9-97 4276.836 0.131 .412 i-53 > 13.20 O.IOO 1.077 ..XT* 12.85 0.059 0.637 o-7oc 11.70 O.O22 0.237 0.27- 10.79 4283.169 0-133 431 i-S5 13-36 0.098 1-055 1-154 12.62 0.059 0.636 0.70! 11.69 O.O2O 0.216 0.25< > 9-97 4284.838 0.134 443 1-56. ! 13-47 0.098 1-055 1-154 12.62 O.o6o 0.646 0.71! 1 11.84 O.O2O 0.215 0.25. 9-93 4287.566 0-133 430 i-55< > 13-35 O.IOO 1.074 1-173 12.82 0.058 0.624 o.69< i 1 1 .48 0.021 0.226 0.26( ) 10.36 4288.310 0.133 430 i-55< > 13-35 0.098 1-055 1-151 12.62 0.058 0.624 o.6 9 ( 11.48 O.O22 0.236 0.27< > 10.75 4289.525 0.134 440 i.5 13-44 O.IOO 1-073 1.172 12.81 O.o6o 0.644 o.7i( > 11.81 O.02I 0.226 0.26( > 10.36 4290.377 o.i34 439 i-5S< ) 13-43 0.098 1-053 1-152 I 2. 60 0.059 0.634 o.7o( ) 11.64 0.020 0.215 0.25. ' 9-93 4290.542 0.134 439 i-55< > 13-43 0.098 1.052 1-151 12-59 0.058 0.623 0-69. 11.46 O.O22 0.236 0.27) > 10.75 4291.630 0-135 449 1.561 ) I3-52 O.IOI 1.084 1.183 12-93 O.o6o 0.644 o-7i( ) 11.81 O.O2O 0.215 0.25. ' 9-93 RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908. 8l TABLE u. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908 Continued. Plate w 135,. 1908, June n, 4 h 5o m G. M. T. Measured by L. on T. Distance from Limb 2.1 mm. Quality, good. p P * i seci o-S O 80.2 10.5 10.5 79-5 4.0 [.002 0-11 5.7 15.5 iS-S 74-5 2.7 i .001 p 11.4 20.5 30.5 59-5 1.4 .000 D 0.8 45-5 45 -S 44-5 I.O .000 Diameter 167.4 mm 60.5 60.5 29-5 0.8 .000 Factor i .026 75-5 75-5 14-5 0.7 .000 90-5 90-5 -o-5 0.7 .000 = - .s = 14!$ = 2p!s X A V f + f, i A V v + v l A t> + , 4196.699 0-173 km 899 km 2-033 14.44 0.162 km 1.779 km .912 a 14.02 0.141 km 1-547 km 1.672 13-64 4197-257 0.174 .910 2.044 14.52 o.i 60 I-7S6 .889 13-35 0.140 1-537 1.662 13-56 4203.730 0.174 .908 2.042 I4-5O 0.164 1.796 .929 14-15 0.143 1-565 1.690 13-79 4207.566 0.174 .904 2-038 14.47 0.164 793 .926 14.12 0-143 1-565 1.690 13-79 4216.136 0.177 931 2.065 14.66 0.164 .790 923 14.10 0.141 1-539 1.664 13-57 4220.509 0.176 1.918 2.052 H-57 0.166 .809 1.942 14.24 0.143 1-554 1.679 13-70 4232.887 0.178 1-933 2.067 14.67 0.164 .791 1.924 14.11 0.142 1-542 1.667 13.60 4233.328 0.179 1.942 2.076 14.74 o.i 68 .824 1-957 14-35 0.142 1-542 1.667 13.60 4257-815 0.180 1.938 2.072 14.71 0.169 -823 1.956 14-34 0.142 1.540 1.665 13-58 4258.477 0.180 1.936 2.070 14.70 0.170 -831 1.964 14.40 0-145 1-564 1.689 13-78 4265.418 0.178 I-9I5 2.049 14-55 0.170 .829 1.962 14-39 0.142 1-529 1.654 13-49 4266.081 0.182 1.963 2.097 14.90 o.i 68 .807 1.940 14-23 0.146 1-570 1.695 13-83 4268.915 0.182 1-953 2.087 14-83 0.170 .820 1-953 14-32 0-143 1-539 1.664 13-57 4276.836 0.180 1.928 2.062 14.64 0.169 .809 1.942 14.24 0.144 1-545 1.670 13.62 4283.169 0.182 1.949 2.083 14-79 o.i 68 1.798 i-93i 14.16 0.146 1.562 1.687 13.76 4284.838 0.180 1.926 2.060 14.63 0.170 1.818 i-95i 14-31 0.147 J-573 1.698 13-85 4287.566 0.181 1-935 2.069 14.69 0.171 1.829 1.962 14-39 0.144 1-542 1.667 13.60 4288.310 O.I 80 1-925 2.059 14.62 0.170 1.817 950 14.30 0.146 1.561 1.686 13-75 4289.525 0.180 1.924 2.058 14.61 0.170 1.820 953 14-32 0-145 i-SSi 1.676 13.67 4290.377 0.180 1.924 2-058 14.61 o.i 68 1-797 930 14-15 0.144 1.540 1.665 13-58 4200.542 0.180 1.924 2.058 14.61 0.170 1.817 950 14.30 0.146 1-553 1.678 13.69 4291.630 0.180 1-923 2.057 14.60 0.169 i. 806 939 14.22 0.146 1-553 1.678 13.69 = 44!s = 59?5 = 74tS = 7o!s A V + ! A V f + 1, g A r + j A V f + t,, I km km km km a km km o km km o 4196.699 O.IO2 1. 122 1.228 12.22 0.060 0.667 0.748 10.46 0.029 0.319 0.370 9.83 O.O20 O.22O o.26c 10.13 4197-257 0.103 I.I30 1.236 12.30 0.062 0.681 0.762 10.66 0.028 0.309 0.360 9-56 0.020 0.220 0.260 10.13 4203.730 0.104 I.I38 1.244 12.38 0.064 0.700 0.781 10.92 0.030 0.329 0.380 10.10 O.O2I 0.229 0.265 10.48 4207.566 O.IO4 1.136 1.242 12.36 0.063 0.690 0.771 10.78 0.029 0.318 0.360 9.80 O.O2I 0.219 0.255 10.09 4216.136 O.IO4 134 I.24C 12.34 0.063 0.690 0.771 10.78 0.030 0.327 0-37* 10.05 0.019 0.208 0.24! 9.66 4220.509 0.106 .156 1.262 12.56 0.063 0.688 0.769 10-75 0.031 0-337 0.388 10.31 O.O2O 0.218 0.258 10.05 4232.887 0.106 151 1-257 12.51 0.064 0.695 0.776 10.85 0.030 0.326 0-377 IO.O2 O.O2O 0.218 0.258 10.05 4233-328 0.106 151 1-257 12.51 0.064 0.695 0.776 10.85 0.030 0.326 0-377 IO.O2 0.021 0.228 0.268 10.44 4257.815 0.105 .132 1.238 12.32 0.063 0.679 0.760 10.63 0.032 0-344 0-395 10.49 O.O2I 0.227 0.267 10.40 4258.477 0.108 .162 1.268 12.62 0.064 0.689 0.770 10.77 0.030 0-324 0-375 9-97 O.O2O 0.216 0.256 9-97 4265.418 0.105 .129 1-235 12.29 0.063 0.678 0.758 10.60 0.032 0-344 Q-395 10.49 O.O22 0.236 0.276 10.75 4266.081 0.107 151 1-257 12.51 0.064 0.687 0.768 10.74 0.030 0.324 0-375 9-97 0.020 0.215 0.255 9-93 4268.915 0.108 .l6l 1.267 12. 6l 0.064 0.687 0.768 10.74 0.032 0-344 0-395 10.49 O.O22 0-235 0.275 10.71 4276.836 0.106 .136 1.242 12.36 0.064 0.687 0.768 10.74 0.031 0-334 0-385 10.23 O.O2I 0.225 0.265 10.32 4283.169 0.106 -134 1.240 12-34 0.066 0.707 0.788 1 1. 02 0.030 0.322 0-373 9.91 0.022 0-235 0-275 10.71 4284.838 0.106 134 1.240 12-34 0.064 0.687 0.768 10.74 0.032 0-344 0-395 10.49 O.O2I 0.224 0.264 10.28 4287.566 0.107 .144 1. 250 12.44 0.064 0.687 0.768 10.74 0.031 0-334 0.385 10.23 O.O2I O.224 0.264 10.28 4288.310 0.106 133 1.239 12-33 0.066 0.707 0.788 1 1. 02 0.032 0-343 0.394 10.46 0.021 0.224 0.264 10.28 4289.525 0.108 154 1.260 12-54 0.066 0.707 0.788 1 1. 02 0.030 0.321 0-372 9.88 0.020 0.213 0-253 9-85 4290.377 0.105 -123 1.221) 12.23 0.064 0.687 0.768 10.74 0.030 0.321 0.372 9.88 O.O2O 0.213 0.253 9.85 4290.542 0.104 "3 I.2I5 12.13 0.066 0.705 0.786 10.99 0.032 0.342 0-393 10.43 0.020 0.213 0-253 9-85 4291.630 0.106 .132 1.238 12.32 0.066 0.705 0.786 10.99 0.030 0.321 0.372 9.88 0.022 0.234 0.274 10.69 8 2 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE n. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS or 1908 Continued. Plate w 135.,. 1908, June ii, 4 h 50 G. M. T. Measured by L. on T. Distance from Limb 1.8 mm. Quality, good. p P T- i] secy o-S O 80.2 10.5 10.5 79-5 4.0 i. 002 G-n s-7 iS-5 iS-5 74-5 2.7 1. 001 p 11.4 30-5 3-S 59-5 i-4 I.OOO D 0.8 45-5 45-5 44-S I.O I.OOO Diameter 167.4 mm 60.5 60.5 29-5 0.8 I.OOO Factor 1.022 75-5 75-5 I4-S 0.7 I.OOO 90-5 90-5 -o-S 0.7 I.OOO = - o?s = I4!S = 29.S X A V . + * 1 A D . + ., * A D . + ,, 4196.699 0.171 km 1.872 km 2.006 14.24 0.161 km 1.762 km 1.895 13.90 0.141 km 1-542 km 1.667 13-60 4197-257 0.172 1.881 2.015 14-31 0.162 1.771 1.904 13.96 0.140 1-533 1-658 13-52 4203.730 0.172 i. 880 2.014 14-30 0.164 1.789 1.922 14.09 0.141 1-539 1.664 13-57 4207.566 0.172 1-875 2.009 14.26 0.164 1-783 1.916 14.06 0-143 1.560 1.685 13-75 4216.136 0.172 1.870 2.004 14.22 0.163 1-772 1.905 13-97 0.141 J-533 1.658 13-52 4220.509 0.175 1.900 2.034 14-43 0.164 1.781 1.914 14.04 0.143 1-553 1.678 13.69 4232.887 0.176 1.902 2.036 14-45 0.165 1.784 1.917 14.06 0.145 1.569 1.694 13.82 4233-328 0.174 1.881 2.015 I4-3 1 0.165 1.784 1.917 14.06 0.146 1-579 1.704 13.90 4257.815 0.179 1.923 2.057 14.60 0.170 1.827 1.960 14-37 0.146 1.566 1.691 13-79 4258.477 0.179 1.921 2-055 14-59 0.169 1.814 1-947 14.28 0-145 1-553 1.678 13.69 4265.418 0.178 1.908 2.042 14.50 0.170 1.824 1-957 14-35 0.146 1-563 1.688 13-77 4266.081 0.181 1.940 2.074 14.72 0.170 1.822 1-955 14-34 0.146 1-563 1.688 13-77 4268.915 0.179 1-913 2-047 14-54 0.171 1-825 1.958 14.36 0.146 1.561 1.686 I3-76 4276.836 0.179 1.911 2.045 14-53 0.170 1.814 1-947 14.28 0.145 i-SSo 1-675 1^.66 4283.169 0.180 1.919 2-053 14-57 0.170 1.813 1.946 14.26 0.147 1.569 1.694 13-82 4284.838 0-179 1.911 2.045 H-S 2 o.i 68 1.791 1.924 14.11 0.145 1.546 1.671 13-63 4287.566 0.181 1.928 2.062 14.64 0.171 1.822 1-955 14-34 0.147 1.568 1.693 13.81 4288.310 0.179 1.901 2-035 14.46 0.171 1.822 1-955 14-34 0.148 1-577 1.702 13.88 4289.525 0.178 1.895 2.029 14-39 0.173 1-843 1.976 14.49 0.146 i-SSS i. 680 I3-7I 4290.377 0.180 1.917 2-051 I4-S6 0.170 1.811 1-944 14.26 0.146 1-555 i. 680 I3-7I 4290.542 o.i 80 1.916 2.050 14-54 0.171 1.821 1-954 14-33 0.146 1-554 1.679 I3-70 4291.630 0.180 1.916 2.050 14-54 0.172 1.831 1.964 14.40 0.146 1-554 1.679 I3-70 = 44!S = S9S = 74!s = 79!s A , + ,, A > , + ,, A V + , A V ,+,, t km km km km km km km km 4196.699 O.IO2 1.116 1.222 12. l6 0.060 0.659 0.740 10.35 0.030 0.329 0.380 IO.IO 0.019 0.209 0.249 9.70 4197-257 O.IO2 1.116 1.222 12. l6 0.060 0.659 0.740 10.35 0.029 0.319 0.370 9-83 0.019 0.209 0.249 9.70 4203.730 0.103 1.124 1.230 12.24 0.062 0.682 0.763 10.67 0.031 0.329 0.380 IO.IO 0.019 0.209 0.249 9.70 4207.566 0.104 I-I34 1.240 12.34 0.062 0.681 0.762 10.66 0.029 0.319 0.370 9-83 O.O2O 0.218 0.258 10.05 4216.136 O.IO4 1-132 1.238 12.32 0.06 1 0.669 0.750 10.49 0.029 0.318 0.369 9.80 0.019 0.207 0.247 9.62 4220.509 O.IO4 1.129 1-234 12.28 0.062 0.677 0.758 10.60 0.030 0.329 0.380 IO.IO O.O2O 0.217 0.257 10.01 4232-887 0.106 1.146 1.252 12.46 0.062 0.674 0-755 10.56 0-030 0.326 0-377 IO.O2 O.OI9 0.206 0.246 9-58 4233-328 0.105 I-I35 I.24I 12.35 0.063 0.684 0.765 10.70 0.030 0.326 0-377 IO.02 0.020 0.216 0.256 9-97 4257.8I5 0.108 1.161 1.207 12. 6l 0.065 0.703 0.784 10.96 0.032 0.346 0-397 10-55 O.O22 0.236 0.276 10-75 4258.477 0.106 1.136 1.242 12.36 0.064 0.690 0.771 10.78 0.031 0.336 0.387 10.28 O.Oig 0.205 0.245 9-54 4265.418 0.104 1.115 1. 221 12.15 0.063 0.679 0.760 10.63 0.032 0-345 0.396 10.52 O.O2O 0.215 0.255 9-93 4266.081 0.107 1.144 I.25O 12.44 0.065 0.702 0-783 10.97 0.031 0-334 0-385 10.23 O.022 0.235 0.275 10.71 4268.915 0.108 I-I54 1.260 12.54 0.066 0.710 0.791 1 1. 06 0.032 0-344 0-395 10.49 O.O2I 0.225 0.265 10.32 4276.836 o.i 06 I-I34 1.240 12.34 0.066 0.708 0.789 11.03 0.032 0-343 0-394 10.47 O.O2I 0.225 0.265 10.32 4283.169 o.i 08 1.152 1.258 12.52 0.066 0.707 0.788 1 1. 02 0.031 0-333 0.384 10.20 O.020 0.215 0-255 9-93 4284.838 o.i 06 1.132 1.238 12.32 0.065 o.6g6 0.777 10.87 0.031 0-333 0.384 IO.2O O.O2I 0.225 0.265 10.32 4287.566 0.108 "1-151 1-257 12.51 0.065 0.696 0.777 10.87 0.032 0-343 0-394 10.47 O.O2I 0.225 0.265 10.32 4288.310 0.107 1.140 1.246 12.40 0.064 0.685 0.766 10.71 0.031 0-333 0.384 10.20 O.020 0.215 0.255 9-93 4289.525 0.106 1.129 1-235 12.29 0.066 0.706 0-787 1 1. 01 0.031 0-333 0-384 IO.2O O.O22 0.245 0.285 II. IO 4290.377 0.104 1.107 I-2I3 12.07 0.065 0.695 0.776 10.86 0.03 1 0-332 0-383 10. 1 8 O.O2I 0.225 0.265 10.32 4290.542 0.104 1.107 I.2I3 12.07 0.067 0.716 0-797 11.15 0.032 0.342 0-393 10.44 O.O2I 0.225 0.265 10.32 4291.630 0.103 1.097 1.203 11.97 0.067 0.716 0-797 11.15 0.032 0.342 0-393 10-44 0.022 0.229 0.269 10.48 RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908. Plate TABLE n. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS or 1908 Continued. 136. 1908, June n, s h 4o m G. M. T. Measured by L. on T. Distance from Limb 1.8 mm. Quality, good. P-P seci; 0.5 O 80.3 10.5 10.5 79-5 4.0 i. 002 0-12 5.8 25-5 25-5 64-5 2.7 1. 000 P 11.4 4-5 4-S 49-5 1.4 i.ooo D 0.8 55-5 55-5 34-5 I.O I.OOO Diameter 167.0 mm 70.5 70.5 19-5 0.8 I.OOC Factor 1.022 85-5 85.5 4-5 0.7 I.OOO 9-5 90-5 -o-S 0.7 I.OOO #~* *-* *-*, X A ' -. + ,, A ' . + ,, * A V , + ., 4196.699 0.172 km 1.882 km 2.016 14-31 o.i 66 kin .819 km 1-953 13-91 0-156 km 707 km 1.838 13.84 4197-257 0.172 1.882 2.016 I4-3I 0.167 .826 1.960 13.96 0.156 .707 1-838 13-84 4203.730 0.174 1.899 2-033 14.42 0.166 .814 1.948 13-87 0.156 703 1.834 13.81 4207.566 0.174 1.896 2.030 14.40 0.167 .821 1-955 13.92 0.158 723 1.854 13-97 4216.136 0.173 1.882 2.016 I4-3I 0.169 -839 1-973 14.06 0.157 703 1-834 13.82 4220.509 0-175 1.896 2.030 14.40 0.171 854 1.988 14.16 0.156 .692 1.823 13-73 4232.887 0-175 l-93 2-037 14.46 0.171 -851 1.985 14.14 0.158 .709 1.840 13-86 4233.328 O.I76 1.903 2.037 14.46 0-173 .870 2.004 14.27 0.158 .709 1.840 13.86 4257-815 o.iSo 1-935 2.069 14.69 0.174 .871 2-005 14.28 0.161 727 1.858 13-99 4258.477 0.180 1.932 2.066 14.66 0.176 .891 2.025 14.42 o.i 60 715 1.846 13.90 4265.418 0.180 1.930 2.064 14.65 0.174 -858 1.992 14.19 o.i 60 .712 1.843 13-88 4266.081 0.180 1.927 2.061 14-63 0.174 .856 1.990 14.17 0.161 .722 1-853 13.96 4268.915 0.180 1.924 2.058 14.60 0.175 -865 1.999 14.24 0-159 .702 1.833 13.81 4276.836 0.180 1.922 2.056 14-59 0-173 845 1-979 14.10 0.162 729 1. 860 14.01 4283.169 0.179 1.911 2.045 I4-52 0.172 834 1.968 14.02 0.162 .728 1.858 13-99 4284-838 0.183 I-95I 2.085 14.80 0-175 .864 1.998 14-23 0.161 .717 1.848 13.92 4287.566 0.179 1.908 2.042 I4-50 0.172 .834 1.968 14.02 0.160 .707 1.838 13-84 4288.310 0.180 .917 2.051 I4-56 0.172 -8 3 2 1.966 14.01 0.163 737 1.868 14.07 4289.525 0.178 .896 2.030 14.40 0.173 .844 1.978 14.09 0.162 .727 1.858 13-99 4290.377 0.180 .917 2.051 14.56 0-173 .844 1.978 14.09 0.162 727 1.858 13-99 4290.542 0.182 937 2.071 14.70 0.174 .852 1.986 14-15 0.162 .727 1-858 13-99 4291.630 0.181 927 2.061 14.63 0.174 .852 1.986 14-15 0.163 735 1.864 14.04 = 34?S = 49?S *-<. - 79?S X A V .+3 A V ..Hi A J) , + r, A t) . + -, 4196.699 0.128 km 1.400 km I.52C 13.09 0.094 km 1.028 km .12; 12.32 0.052 km 1.569 km 0.641 10.57 O.022 km 0.240 km 0.280 O 10.91 4197-257 0.128 1.400 I-52C 13-09 0.094 1.028 .125 12.32 0-052 1.569 0.641 10.57 0.020 0.220 0.260 IO.I2 4203.730 0.130 1.420 I-S4C 13-27 0.098 1.065 12.72 0.052 I-567 0.635 10.54 O.O2O 0.219 0.255 10.10 4207.566 0.130 1.417 1-537 13-24 O.IOI I.IO2 .201 13-13 0-054 1-590 0.66; 10.92 O.O2I 0.029 0.265 10.48 4216.136 0.128 1.392 1.515 13-03 0.097 I.O52 151 12.58 0.051 1-555 0.62; 10.34 0.020 0.219 0.25? io.ro 4220.509 0.132 I-43I 13-36 0.099 1.070 .165 12.78 0.054 1-588 o.66c 10.88 O.O2I 0.228 0.268 10.44 4232.887 0.132 1.428 1.54? 13-34 0.097 1.048 .14; 12.54 0.054 1-585 0.655 10.83 O.O2O 0.218 0.258 10.06 4233.328 0.132 1.428 i- 54^ 13-34 0.097 1.048 147 12.54 0-053 1-574 0.646 10.65 0.020 0.218 0.258 10.06 4257-815 0.134 1.440 i-56c 13-44 O.IOO 1.074 1.171 12.82 0.054 1.580 0.652 10.76 O.O22 0.236 0.276 10.75 4258.477 0-134 J-439 1.555 13-43 0.098 I.O52 1.151 12.58 0.054 1-579 0.651 10.74 O.O2O 0.216 0.256 9-97 4265.418 0-134 1-437 1-55! 13-41 0.099 I. O6 1 i.i6c 12.68 0-055 1.589 0.661 10.90 0.022 0.236 0.276 10.75 4266.081 0.134 1-435 i-ss: 13-40 O.IOI I.oSl i.iSc 12.90 0-054 1-579 0.651 10.74 O.O22 0-236 0.276 10.75 4268.915 0-135 1.441 1.561 13-45 O.IOO I.O7O 1.165 12.78 0-055 1.589 0.661 10.90 O.O22 0.236 0.276 10.75 4276.836 0-135 1.441 1.561 13-45 O.IOO 1. 068 1.16; 12.76 0.056 1-599 0.671 11.07 O.O2O 0.216 0.256 9-97 4283.169 0-134 1.431 1-551 13-36 O.IOO 1. 066 .16 = 12.74 0.056 1.596 11.02 0.022 0.236 0.276 10-75 4284.838 0-135 1.446 1-566 13-49 0.099 1-057 156 12.64 0-056 1.596 o.66f 1 1. 02 O.O2O 0.214 0.254 9.90 4287.566 0-134 1-551 13-36 0.098 1.046 12.52 0.056 1-595 0.66; II.OO 0.021* 0.225 0.265 10.32 4288.310 0.136 1.449 1-565 13-52 O.IOO 1.065 12.72 0-053 1-564 0.636 10.48 0.022 0.235 0.275 10.71 4289.525 0-135 1.441 1-561 13-45 O.IOO 1.064 !i6; 12.71 0-055 1.607 0.675 II. 2O O.O2I 0.225 0.265 10.32 4290.377 0-134 I-43I i-55i 13-36 0.099 1-054 12.60 0.056 1-597 0.665 11.04 O.O2O 0.214 0.254 9.90 4290.542 0.136 1.448 1-568 13-51 0.098 1.044 1-145 12-49 0.056 J-597 0.665 11.04 0.020 0.214 0.254 9.90 4291.630 0.136 1.449 1.565 13-52 0.099 1-053 1.155 12-59 0.058 1.607 0.675 II. 2O O.O22 0.235 0.275 10.71 84 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE n. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS or 1908 Continued. Plate w 146. 1908, Aug. 5, 9 h 50"" G. M. T. Measured by L. on T. Distance from Limb 1.3 mm. Quality, good. P-P seer) -0-3 O 133.0 13.2 14.6 7S-4 2S-3 .106 O-Si 58.5 28.7 29-3 60.7 12.7 .025 p -12.7 44.2 44-5 45-S 8.8 .012 D 6.2 59-7 59-9 30.1 7.2 .008 Diameter 168.6 mm 74-7 74.8 15.2 6.4 .006 Factor 1.016 89.7 89.7 0-3 6.2 .O06 = ota = ** = 3* A tl , + ,, A V , + ,, A . + ,, 1 4196.699 0.171 km 1.872 km 2.006 14.24 0.164 km 1.794 km 1.926 14.17 0-139 km 525 km .646 13-51 4197-257 0.172 1.881 2.015 I4-3I 0.165 1.804 1.936 14.24 0.140 533 654 13-57 4203.730 0.173 1.887 2.021 14-35 0.166 1.810 1.942 14.29 0.140 530 .651 13-55 4207.566 0.170 1.854 1.988 14.11 0.165 1.798 1.930 14.20 0.142 551 .672 13.72 4216.136 0.172 1.870 2.004 I4-23 0.165 1-794 1.926 14.17 0.141 535 .656 13-59 4220.509 0-173 1.879 2.013 14.29 o.i 66 .802 1-934 14-23 0.140 523 .644 13-49 4232-887 0.176 1.904 2.038 14.47 0.167 -805 937 14-25 0.141 529 650 13-54 4233-328 0.177 1.914 2.048 14-54 0.167 .805 937 14-25 0.142 538 659 13.61 4257-815 0.178 I-9I3 2.047 14-53 0.169 -815 947 14-32 0.144 546 .667 13.68 4258.477 0.177 1.902 2.036 14-45 0.167 .791 923 14-15 0.143 -536 .657 13.60 4265.418 0.178 1.901 2-035 14-45 0.168 .800 932 14.21 0.143 -536 .657 13.60 4266.081 0.179 1.918 2.052 14-57 0.170 .819 951 14-35 0.143 -536 657 13.60 4268.915 0.180 1.927 2.061 14-63 0.168 799 .931 14.21 0.143 535 .656 13-59 4276.836 0.178 1.898 2.032 14.42 0.168 794 .926 14.17 0.144 538 -659 13.61 4283-169 0.178 1.897 2.031 14.42 0.170 .812 944 14-30 0.144 538 659 13.61 4284.838 0.179 1.907 2.O4I 14.49 0.168 792 924 14-15 0.143 527 1.648 I3-52 4287.566 0.177 1.886 2.020 14.34 0.170 .812 1.944 14-30 0.143 -526 1.647 I3-52 4288.310 0.178 1.895 2.029 14.40 o.i 68 790 1.922 14.14 0.147 570 1.691 13.88 4289-525 0.177 1.885 2.OI9 14.33 0.170 .810 1.942 14.29 0-143 -530 1.651 13-55 4290.37? 0.178 1.896 2.030 14.41 0.171 .820 1-952 14-36 0-143 -528 1.649 13-53 4290.542 0.179 1.905 2.039 14.48 0.169 .798 1.930 14.20 0.144 537 1.658 13-61 4291-630 0.178 1.894 2.028 14.40 o.i 68 .790 1.922 14.14 0.146 557 1.678 13-77 = *, = 6!? = 7St4 4196.699 0.105 I-I55 1.256 12.72 0.059 0.652 0.725 10.53 0.028 0-337 0-377 10.62 4197-257 0.105 i-iSS 1.256 12.72 0.059 0.652 0-725 10.53 0.030 0.361 0.401 11.29 4203-730 o.i 06 1.163 1.264 1 2. 80 0.063 0.698 0.771 1 1. 20 0.032 0.382 0.422 11.88 4207.566 o.i 06 1.162 1.263 12-79 0.062 0.685 0.758 II.OI 0.030 0.360 0.400 11.27 4216.136 0.106 1.156 1-257 12.73 0.062 0.683 0.756 10.98 0.029 0.348 0.388 10.93 4220.509 0.106 i-iS5 1.256 12.72 0.062 0.683 0-756 10.98 0.030 0-358 0.398 II. 21 4232-887 0.106 1-254 12.70 0.062 0.683 0.756 10.98 0.031 0.369 0.409 11-52 4233.328 0.108 175 1.276 12.92 0.064 0.705 0.778 11.30 0.030 0-357 0-397 ii. 18 4257-815 0.108 .168 1.269 12.85 0.064 0.701 0.774 11.24 0.032 0.376 0.416 11.72 4258.477 0.109 .174 1-275 12.91 0.064 0.698 0.771 ii. 20 0.031 0.365 0.405 11.41 4265.418 0.107 153 1.254 12.70 0.064 0.698 0.771 ii. 20 0.032 0.376 0.416 11.72 4266.081 O.IIO .186 1.287 13.04 0.063 0.688 0.761 11.05 0.031 0-365 0.405 11.41 4268.915 0.109 .172 1.273 12.89 0.064 0.695 0.768 11.15 0,032 0-375 0.415 11.69 4276.836 0.107 .150 1.251 12.67 0.064 0.695 0.768 11.15 0.030 0.352 0.392 11.04 4283.169 0.108 159 1.260 12.76 0.063 0.684 0-757 10.99 0.031 0.364 0.404 11-38 4284.838 0.108 .158 1-259 12.75 0.062 0.675 0.748 10.86 0.033 0.386 0.426 12.00 4287.566 0.108 157 1.258 12.74 0.062 0.675 0.748 10.86 0.031 0-363 0.403 "35 4288.310 O.IIO .178 1.279 12.95 0.064 0.694 0.767 11.14 0.032 0-375 0-415 11.69 4289.525 0.108 .170 1.271 12.87 0.062 0.674 0.747 10.85 0.031 0.363 0.403 "35 4290.377 0.109 .179 1.280 12.96 0.06 1 0.663 0.736 10.69 0.030 0-352 0.392 11.04 4290.542 0.108 .168 1.269 12.85 0.063 0.683 0.756 10.98 0-033 0.386 0.426 12. OO 4291-630 0.108 1.167 1.268 12.84 0.060 0.651 0.724 10.51 0.030 0.392 11.04 RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908. TABLE n. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908 Continued. Plate < 147. 1908, Aug. 5, io h 30 G. M. T. Measured by L. on T. Distance from Limb 1.5 mm. Quality, good. P-f seci -0.3 i33-o 13.2 14.6 754 25-3 1.106 O-n S8.S 28.7 29-3 60.7 12.7 1.025 p -12.7 44.2 44-5 45-S 8.8 I.OI2 D 6.2 59-7 59-9 30.1 7.2 1.008 Diameter 168.6 mm 74-7 74.8 15-2 6.4 1. 006 Factor 1.018 89.7 89.7 0-3 6.2 I. OO6 = 3 = is!* = 3!i A V " + ! A r fl + l A V 11 + 11 l { 4196.699 0.174 km I-905 km 2.039 14.48 0.164 km 1.796 km 1.928 14.18 O.H3 km 1.568 km 1.689 13-86 4I97-257 0.174 I-905 2.039 14.48 0.165 1. 806 1.938 14.26 0.143 .568 1.689 13.86 4203.730 0.075 1.912 2.046 H-53 0.167 1-825 1-957 14.40 0.144 578 1.699 13-94 4207.566 0.176 I.92I 2-055 M-59 0.168 1.833 1.965 14.46 0.144 574 1.695 13-91 4216.136 0-175 I-905 2.039 14.48 o.i 66 1.807 1-939 14.26 0.143 554 I.675 13-75 4220.509 0.176 I-9H 2.048 14-54 o.i 68 1.827 1-959 14.41 0.145 574 1.695 I3-9I 4232.887 0.177 I-9I7 2.051 14.56 0.168 1.820 1.952 14.36 0-145 573 1.694 13.90 4233-328 0.178 1.927 2.061 14.63 0.168 .819 I-95I 14-35 0.144 562 1.683 13.81 4257-8I5 0.179 1-925 2.059 14.62 0.170 .828 1.960 14.42 0.146 570 1.691 13.88 4258.477 0.178 I-9H 2.048 14-54 0.170 .828 1.960 14.42 0.146 i-57o 1.691 13-88 4265.418 0.179 1.922 2.056 14.60 0.173 .856 1.988 14.62 0.146 1.569 1.690 13-87 4266.081 0.180 I-93I 2.065 14.06 0.170 .825 1-957 14.40 0.144 1-542 1.663 13-65 4268.915 0.178 1.908 2.042 14.50 0.170 .823 1-955 14.38 0.148 -583 1.704 13.98 4276.836 0.179 1.916 2.050 14-55 0.171 .826 1.958 14.40 0.146 -562 1.683 13.81 4283.169 0.180 1.921 2-055 14-59 0.171 .826 1.958 14.40 0.145 551 1.672 I3-72 4284.838 0.180 1.920 2.054 14.58 0-173 .847 J-979 14.56 0.146 .565 1.686 13.84 4287.566 0.181 1-930 2.064 14.65 0.172 .835 1.967 14.47 0.146 -564 1.685 I3-83 4288.310 0.180 1.919 2-053 14.58 0-173 .846 1.978 14-55 0.145 554 1-675 13-74 4289.525 0.181 1.929 2.063 14.65 0.174 .856 1.988 14.63 0.148 .581 1.702 13-97 4290.377 0.180 1.919 2-053 14.58 0.170 .812 1-944 14-30 0.146 562 1.683 13-81 4290.542 0.180 1.918 2-052 14-57 0.171 .822 1-954 14.38 0.145 552 1-673 13-73 4291.630 0.180 1.918 2-052 14-57 0.172 1.832 1.964 14-45 0.148 .580 1.701 13.96 = 4s!s = 6o! 7 = 7S?4 4196.699 O.IO2 -132 1-233 12.49 0.062 0.689 0.762 11.07 0.029 0-349 0.389 10.96 4I97-257 O.IO4 -145 1.246 12.62 0.062 0.689 0.762 11.07 0.030 0.358 0.398 II. 21 4203.730 0.106 .164 1.265 12.81 0.063 0.698 0.771 n. 20 0.030 0-357 0-397 ii. 18 4207.566 0.106 .163 1.264 12.80 0.063 0.698 0.771 11.20 0.030 0-357 0-397 ii. 18 4216.136 0.107 .171 1.272 12.88 0.063 0.697 0.770 II.I8 0.029 0-347 0.387 10.90 4220.509 0.106 157 1.258 12.74 0.063 0.697 0.770 ii. 18 0.032 0-379 0.419 11.80 4232-887 0.106 .156 1-257 12-73 0.063 0.697 0.770 11.18 0.030 0-354 0-394 II. IO 4233-328 0.108 .176 1-277 12.93 0.066 0.727 0.800 11.62 0.030 0-354 0-394 II. IO 4257-8I5 0.109 .179 1.280 12.96 0.066 0.719 0.792 11.50 0.032 0.370 0.410 "55 4258.477 O.IIO .189 1. 200 13-07 0.066 0.719 0.792 11.50 0.032 0.370 0.410 "55 4265.418 0.108 .162 1.263 12.79 0.066 0.719 0.792 11.50 0.032 0.370 0.410 "55 4266.081 0.108 .162 1.263 12.79 0.065 0.706 0.779 11.31 0.030 o.35o 0-390 10.98 4268.915 0.109 171 1.272 12.88 0.065 0.706 0-779 11.31 0.030 0-350 0.390 10.98 4276.836 O.I OQ .171 1.272 12.88 0.066 0.715 0.788 11.44 0.031 0.360 0.400 11.27 4283.169 0.108 .160 1.261 12.77 0.065 0.705 0.778 11.30 0.032 0.370 0.410 "55 4284.838 O.I I I .192 1.293 13.10 0.066 0.715 0.788 11.44 0.032 0-370 0.410 "55 4287.566 0.108 -163 1.264 12.80 0.068 0.738 0.811 11.78 0.032 0.370 0.410 "55 4288.310 O.IIO .182 1-283 13.00 0.067 0.728 0.801 11.63 0.030 0.350 0.300 10.98 4289.525 O.III .191 1.292 13.09 0.065 0.705 0.778 11.30 0.032 0.370 0.410 "55 4290.377 0.109 .169 1.270 12.86 0.064 0.695 0.768 11.15 0.031 0.360 0.400 11.27 4290.542 0.109 .169 1.270 12.86 0.065 0.704 0.777 11.28 0.030 0.350 0-390 10.98 4291.630 O.IIO .179 1.280 12.96 0.065 0.704 o-777 11.28 0.033 0.385 0-425 11.97 86 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. Plate TABLE n. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908 Continued. 148. 1908, Aug. 5, io h 30 G. M. T. Measured by L. on T. Distance from Limb 1.4 mm. Quality, good. v p P "" *7 -0.3 O 133.0 13.2 14.6 75-4 2S-3 .106 0-0 58.5 28.7 29-3 60.7 12.7 .025 p -12.7 44-2 44-5 45 -S 8.8 .012 1 D 6.2 59-7 59-9 30.1 7.2 .008 Diameter 168.6 mm 74-7 74.8 15-2 6.4 .006 Factor i .01 7 89.7 89.7 0-3 6.2 .OO6 0=o?3 *-*. = 3o!i A V . + A ,-M, A a ,-M, * 4196.699 0.173 km 1.896 km 2.030 14.41 o.i 66 km 1.817 km 1-949 14-34 0.142 km 1-558 km 1.679 o 13-78 4197.257 0-175 1.916 2.050 14-55 0.165 1.807 1-939 14.26 0.143 1.568 1.689 13.86 4203.730 0.174 1.903 2.037 14.46 o.i 66 1.811 1-943 14.29 0.144 1-576 1.697 13-93 4207.566 0.176 1.921 2-055 14-59 0.167 1.821 1-953 14-37 0.146 1-597 1.718 14.10 4216.136 0.176 I-9I3 2.047 14-53 0.167 1.818 1.950 14-35 0.144 i-57o 1.691 13.88 4220.509 0.178 1.936 2.070 14.70 0.169 1-831 1.963 14.44 0-145 1-579 1.700 13-95 4232.887 0.176 1.911 2.045 I4-52 0.167 1.811 1-943 14.29 0-145 1-573 1.694 13.90 4233.328 0.178 1.927 2.061 14.64 0.170 1.841 1-973 14-52 0.144 1.562 1.683 13.81 4257.815 0.178 I-9I5 2.049 14-55 0.170 1.827 1-959 14.41 0.146 1-574 1.695 13-91 4258.477 0.178 I-9I4 2.048 14-54 0.168 1.807 1-939 14.26 0.147 1-583 1.704 13.98 4265.418 0.180 .929 2.063 14-65 0.170 1.824 1.956 14-39 0.145 1.560 i. 68 1 13-79 4266.081 0.180 .928 2.062 14.64 0.170 1.824 1.956 14-39 0.146 1.569 1.690 13-87 4268.915 0.178 .908 2.042 I4-50 0.172 1.842 1-974 14-52 0.146 1-563 1.684 13.82 4276.836 o.i75 -873 2.007 14.27 0.172 1.841 1-973 14.52 0-147 1-573 1.694 13.90 4283.169 0.181 935 2.069 14.69 0.170 1.815 1-947 14-33 0.146 1.562 1.683 13.81 4284.838 0.182 945 2.079 14-76 0.170 1-815 1-947 14-33 0.146 1.561 1.682 13.80 4287.566 0.182 943 2.077 14-75 0.173 1.849 1.981 14-57 0.144 1.540 1.661 13-63 4288.310 0.181 931 2-065 14.66 0.172 1-837 1.969 14.49 O.I4S 1-550 1.671 i3-7i 4289.525 0.182 .941 2.075 14-73 0.172 1.836 1.968 14.48 0.147 1-570 1.691 13.88 4290.377 0.181 929 2.063 14.65 0.172 1-835 1.967 14.47 0.147 1-570 1.691 13.88 4290.542 0.182 939 2.073 14.72 0.174 1-853 1.985 14.60 0.146 1-559 i. 680 13-78 4291.630 0.182 939 2.073 14.72 0.172 1-833 1.965 14.46 0.146 1-559 i. 680 I3-78 = 4S!S = 6o7 = rs!4 4196.699 0.107 1.177 1.278 12.94 0.064 0-713 0.786 11.41 0.029 0.348 0.388 10.93 4197.257 0.105 i-i57 1.258 12.74 0.064 0-713 0.786 11.41 0.030 0-358 0.398 II. 21 4203.730 0.106 1.165 1.266 12.82 0.067 0-733 0.806 11.70 0.030 0-358 0.398 II. 21 4207.566 0.107 1.174 1-275 12.91 0.065 0.721 0-794 11-53 0.031 ! 0.368 0.408 11.49 4216.136 0.106 1.158 1.259 12-75 0.064 0.710 0.783 ii-37 0.030 ' 0.356 0-396 11.15 4220.509 0.108 1.177 .278 12.94 0.066 0.730 0.803 11.66 0.031 0.366 0.406 H-43 4232.887 0.107 1.165 .266 12.82 0.068 0.738 0.811 11.78 0.031 0.366 0.406 II -43 4233.328 0.107 1.165 .266 12.82 0.065 0.716 0.789 11.46 0.032 0.376 0.416 11.72 4257-815 0.107 I-I53 254 12.70 0.068 0-733 0.806 11.70 0.031 0.361 0.401 11.29 4258.477 0.108 1.163 .264 12.80 0.068 0-732 0.805 11.69 0.032 o-37i 0.411 11-58 4265.418 0.107 1.153 254 12.70 0.068 0-731 0.804 11.67 0.031 0.361 0.401 11.29 4266.081 0.108 .163 .264 12.80 0.066 0.720 0-793 11.52 0.031 0.361 0.401 11.29 4268.915 0.107 151 -252 12.68 0.068 0.728 0.801 11.63 0.032 0-371 0.411 11.58 4276.836 0.108 .161 .262 12.78 0.068 0.728 0.801 11.63 0.032 0.371 0.411 11-58 4283.169 O.IIO .181 .282 12.98 0.069 0.738 0.811 11.78 0.031 0.361 0.401 11.29 4284.838 0.108 159 .260 12.76 0.067 0.718 0.791 11.49 0.032 0.360 0.400 11.27 4287.566 0.107 .149 .250 12.66 0.068 0.728 0.801 11.63 0.030 0-350 0.390 10.98 4288.310 0.108 .161 .262 12.78 0.067 0.727 0.800 11.62 0.032 0-370 0.410 "-5S 4289.525 O.IIO .181 1.282 12.98 0.068 0.726 0.799 1 1. 60 0.031 0.360 0.400 11.27 4290.377 0.108 .160 1.261 12.77 0.066 0.718 0.791 n-49 0.032 0.370 0.410 ii-5S 4290.542 O.IIO .179 1.280 12.96 0.067 0.726 0.799 1 1. 60 0.032 0.370 0.410 "55 4291.630 0.108 .158 1-259 12.75 0.067 0.726 0-799 11.60 0.031 0.360 0.400 11.27 RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908. TABLE n. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908 Continued. Plate w 151. 1908, Aug. 6, s h 15 G. M. T. Measured by L. on T. Distance from Limb 1.5 mm. Quality, good. P-P 'I' secij o-3 133-8 13-8 iS-i 74-9 24.6 1. 100 o-n 59-3 29.6 30.2 59-8 12-5 1.024 p -13.1 45-i 45-4 44.6 8.8 1.012 D 6.3 75-3 75-4 14.6 6.4 1. 006 Diameter 168.6 mm 9-3 9-3 -0-3 6.2 I. OO6 Factor 1.018 = i4?6 A V + V 1 J A V V -fllj J A V + ! 1 km km km km - km km 4196.699 0.174 1.908 2.042 14.50 0-173 1.899 2-033 14-43 0.163 1.788 1.920 14.09 4I97-2S7 O.I7S 1.918 2.052 14-57 0-175 1.918 2.052 14-57 0.164 1.797 1.929 I4-IS 4203.730 0.177 1.936 2.070 14.70 0.178 1.936 2.070 14.70 0.166 1.815 1-947 14.28 4207.566 0.176 .918 2.052 H-57 0.177 1.928 2.062 14.64 0.165 1.803 1-935 14.20 4216.136 0.176 915 2.049 14-55 0.175 I-905 2.039 14-47 0.165 1.799 I-93I 14.17 4220.509 0.176 .911 2.045 14-52 0.177 1.921 2.055 14.60 0.167 1.813 1-945 14.28 4232.887 0.180 949 2.083 14.79 0.176 1.908 2.042 14.50 0.168 I.82I 1-953 14-32 4233-328 0.177 .918 2.052 M-57 0.177 1.918 2.052 14-57 o.i 68 I.82I 1-953 14.32 4257-8I5 0.180 937 2.071 14.71 0.180 1-937 2.071 14.71 0.169 1.819 i-95i I4-3 1 4258.477 0.182 959 2.093 14.86 0.179 1.928 2.062 14.64 o.i 68 1.809 1.941 14.24 4265.418 0.179 923 2.057 14.61 0.180 1-933 0.067 14.68 0.170 1.827 1-959 14.38 4266.081 O.I 80 932 2.066 14.67 0.179 1.922 2.056 14.61 0.170 1.826 1.958 14-37 4268.915 0.180 93 2.064 14.66 0.180 1.930 2.064 14-65 0.171 1.829 1.961 14-39 4276.836 0.180 .928 2.062 14.64 0.180 1.928 2.062 14.64 0.171 1.828 1.960 14-38 4283.169 0.181 933 2.067 14.68 0.179 I-9I3 2.047 14-54 0.170 1.818 1.950 14.30 4284.838 0.181 933 2.067 14.68 0.181 1-933 2.067 14.68 0.172 1.838 1.970 14-45 4287.566 0.180 .922 2.056 14.60 0.181 1.932 2.066 14.67 0.170 1.818 1.950 14.30 4288.310 0.179 .912 2.046 H-53 0.181 1-932 2.066 14.67 0.172 1-837 1.969 14.44 4289.525 0.182 1.942 2.076 14.74 0.182 1.942 2.076 14.74 0.171 1.827 1-959 14-37 4290.377 O.I 80 1.921 2.055 14-59 0.181 I-93I 2.065 14.66 0.171 1.827 1-959 14-37 4290.542 0.182 1.942 2.076 14-74 0.181 1.932 2.066 14.67 0.173 1.845 1.977 14.50 4291.630 0.181 I-93I 2.065 14.66 0.182 1.941 2.075 14-73 0.172 1-835 1.967 H-43 = 44!6 = sots = 74!9 4196.699 0.105 159 .260 12.56 0.065 0.724 0.797 11.25 0.029 0.348 0.388 10.57 4I97-257 0.105 .158 259 12.55 0.064 0.714 0.787 II. II 0.030 0.358 0.398 10.85 4203.730 0.106 .164 .265 12. 6l 0.066 0-734 0.807 "39 0.030 0-357 0-397 10.82 4207.566 0.106 .162 .263 12-59 0.067 0-745 0.818 "55 0.031 0.368 0.4,08 II. 12 4216.136 0.104 .140 .241 12.37 0.066 0.732 0.805 11.36 0.031 0.367 0.407 II.O9 422O.5O9 0.106 159 .260 12.56 0.066 0.732 0.805 11.36 0.030 0-357 0-397 10.82 4232.887 0.108 .178 .279 12.75 0.067 0-739 0.812 11.46 0.031 0-365 0.405 11.03 4233-328 0.108 .178 .279 12.75 0.068 0-749 0.822 1 1. 60 0.031 0-365 0.405 11.03 4257-8I5 0.109 177 .278 12.74 0.069 0-753 0.826 11.66 0.033 0.388 0.428 11.66 4258.477 0.108 .166 1.267 12.63 0.067 0-733 0.806 11.38 0.032 0.376 0.416 "34 4265.418 0.108 .164 1.265 12.61 0.064 0.702 0-775 10.94 0.032 0.376 0.416 "34 4266.O8I 0.109 174 1-275 12.71 0.065 0.711 0.784 1 1. 06 0.032 0-374 0.414 11.28 4268.9J5 0.108 .164 1.265 12.61 0.069 0.750 0.823 11.61 0.032 0-374 0.414 11.28 4276.836 0.109 .172 1-273 12.69 0.068 0-739 0.812 11.46 0.032 0-374 0.414 11.28 4283.169 O.IIO .182 1.283 12.79 0.068 0-739 0.812 11.46 0.033 0.384 0.424 "55 4284.838 0.109 .171 1.272 12.68 0.068 0-739 0.812 11.46 0.034 0.396 0.436 11.88 4287.566 O.IIO .181 1.282 12.78 0.069 0-749 0.822 1 1. 60 0.034 0.396 0-436 11.88 4288.3IO 0.108 .161 1.262 12.58 0.066 0.718 0.791 ii. 16 0.032 0.374 0.414 11.28 4289.525 0.109 .170 1.271 12.67 0.068 0-739 0.812 11.46 0.032 0-374 0.414 11.28 4290.377 0.109 1.170 1.271 12.67 0.068 0-739 0.812 11.46 0-033 0.385 0.425 11.58 4290.542 O.IIO 1.180 1.281 12.77 0.068 0-739 0.812 11.46 0.033 0.396 0.436 11.88 4291.630 O.IIO 1.180 1.281 12.77 0.071 0.771 0.844 n-75 0.034 0.396 0.436 11.88 88 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE n. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS or 1908 Continued. Plate w 161. 1908, Aug. 26, n h o m G. M. T. Measured by L. on T. Distance from Limb i.i mm. Quality, good. P-P secy -0-3 153-3 24.1 25.0 65.0 17.0 1.049 o-n 78.8 40.1 40.6 49.4 II. 1.018 p -19.8 SS'S 55-8 34.2 8.6 1.016 D 7.1 70.7 70.9 19.1 7-5 1.009 Diameter 168.9 mm 79.0 79.1 10.9 7.2 1.008 Factor 1.013 83.8 85.8 4.2 7-i 1.008 = 4! 2 = IOQ = I9?i A V v + v t i A V v + v 1 i A V + ! i 4196.699 0.172 km 1.879 km 2.015 14-34 o.i 68 km 1.836 km 1.970 14.24 0.159 km 1-739 km 1.867 o 14.04 4197-25? 0.1/3 1.888 2.024 14.41 o.i 68 1.836 1.970 14.24 0.159 1-739 1.867 14.04 4203.730 0.175 1-913 2.049 14-59 0.169 1.840 1.974 14.27 0.162 1.766 1.890 14.21 4207.566 0-175 1.910 2.046 14.56 o.i 68 1.828 1.962 14.19 0.161 1-753 I.88I 14.14 4216.136 O.I7S 1.908 2.044 14-55 o.i 68 1.826 1.960 14.17 0.161 1-75' 1.879 14.13 4220.509 0.176 1.905 2.041 14-53 0.172 1.867 2.001 14.47 0.163 .766 !.894 14.24 4232.887 0.176 1.902 2-038 14-51 0-173 1.869 2.003 14.49 0.164 774 1.902 14.30 4233-328 0.176 1.902 2.038 14-51 0.172 1.859 1-993 14.42 0.165 .784 1.912 14.37 4257-815 0.179 1.920 2.056 14.63 0.176 1.884 2.018 14.59 0.163 744 1.872 14.08 4258-477 0.178 1.910 2.046 14.56 0.174 1.864 1.998 14-45 0.164 753 i. 88 1 14.14 4265.418 0.179 1.918 2.054 14.62 0.172 1.842 1.976 14.29 0.164 753 1.881 14.14 4266.081 0.179 1.917 2-053 14.61 O.I7S 1.867 2.OOI 14.47 0.167 1-783 1.911 14.36 4268.915 0.180 1.926 2.062 14.68 0.174 1.856 1.990 14-39 0.166 1.772 1.900 14.28 4276.836 0.176 1.878 2.014 14-34 0.174 1-855 1.989 14.38 0.164 I-75I 1.879 14.13 4283.169 0.180 1.918 2.054 14.62 0.175 1.865 1.999 14.46 0.167 .781 1.909 14.35 4284.838 0.180 1.916 2.052 14.61 0.174 I.8S5 1.989 14.38 0.165 .760 1.888 14.19 4287.566 0.180 1.916 2.052 14.61 0.175 1.864 1.998 14-45 0.165 .760 1.888 14.19 4288.310 0.179 1.906 2.042 14-54 0-175 1.864 1.998 14-45 0.165 .760 1.888 14.19 4289-525 0.179 1.906 2.042 14-54 0.174 1-854 1.988 14.38 0.162 .725 1-853 13.93 4290.377 0.179 1.905 2.041 14-53 0.174 1.854 1.988 14.38 0.162 725 1-853 13.93 4290.542 0.180 1-915 2.051 14.60 0.174 1-853 1.987 14.37 0.164 747 1-875 14.10 4291.630 0.180 1-915 2.051 14.60 0.176 1.873 2.OO6 14.51 o.i 66 .768 1.896 14.25 = 34?2 = 49A = 65! 4196.699 0.128 1.404 I-5I9 13-03 0.088 0.972 1.061 11.57 0.048 0.541 0-599 10.06 4197-25? 0.128 1.404 I-5I9 13-03 0.088 0.972 1. 06 1 "57 0.048 0.541 0-599 10.06 4203 730 0.128 1.412 -528 13.12 0.090 0.992 1.081 11.79 0.049 0-551 0.609 10.23 4207.566 0.131 1.430 545 13-25 0.090 o 990 1079 11.77 0.050 0.561 0.619 10.40 4216.136 0.132 1.438 553 13-32 0.090 0.988 1.077 "75 0.047 0-530 0.588 9.88 4220.509 0.131 1.426 541 13.22 0.092 1.005 1.094 "93 0.050 0-559 0.617 10.37 4232.887 0.132 1-434 549 13.29 0.091 0.994 1.083 11.81 0.051 0.569 0.627 10.54 4233.328 0.132 I-43I 546 13.26 0.090 0.984 1-073 11.70 0.051 0.569 0.627 10.54 4257-815 0-135 1.450 -565 13-43 0.092 0.996 1.085 11.83 0.054 0-599 0.657 11.04 4258.477 0-135 1.450 565 13-43 0.092 0.996 1.085 11-83 0.054 0.598 0.656 n. 02 4265.418 o-i33 1.429 544 13-24 0.090 0-974 1.063 n-59 0-053 0.588 0.646 10.85 4266.081 0-135 1-445 .560 13-38 0.092 0.992 1.081 11-79 0.052 0-575 0-633 10.63 4268.915 0-135 445 560 13-38 0.093 1. 002 1.091 11.90 0-053 0-585 0.643 10.80 4276.836 0-133 424 539 13.20 0.092 0.992 1.081 11.79 0.053 0.585 0.643 10.80 4283.169 0-134 435 550 13-30 0.092 0.992 1.081 11.79 0.052 0-575 0.633 10.63 4284.838 0.134 435 550 13-30 0.090 0.972 1. 06 1 n-57 0.052 0.576 0.634 10.65 4287.566 0.134 -435 550 13-30 0.092 0.991 1.080 11.78 0-053 0.586 0.644 10.82 4288.310 0.136 451 -566 13-43 0.093 1. 001 1.090 11.89 0.053 0.586 0.644 10.82 4289.525 0-133 .421 -536 13.18 0.092 0.991 1.080 11.78 0.051 0-565 0.623 10.47 4290.377 0-135 .441 -556 13-35 0.091 0.981 1.070 11.67 0.052 0-575 0.633 10.63 4290.542 0.135 1.441 -556 13-35 0.093 1. 001 1.090 11.89 0.054 0-595 0-653 10.97 4291.630 0.133 1.420 535 13-17 0.095 1. 02 1 I. IIO 12. II 0.054 0-595 0-653 10.97 RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908. 8g TABLE n. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908 Continued. Plate w 162. 1908, Aug. 26, ii 1 ' o m G. M. T. Measured by L. on T. Distance from Limb i.i mm. Quality, good. P-P seer] -0.3 153-3 24.1 25.0 65.0 17.0 1.046 O-n 7 8.8 40.1 40.6 49.4 II.O 1.019 P -19.8 55-5 55-8 34-2 8.6 1. 01 1 D 7.1 70.7 70.9 19.1 7-5 1.009 Diameter 168.9 mm 79.0 79.1 10.9 7.2 1. 008 Factor 1.013 85.8 85.8 4.2 7-i 1.008 = 4!* = io9 = IQ!I . A ' . + ., s* A V + , A V . + ,, 4196.699 0.174 km 1.901 km 2.037 i 4 5 o o.i 68 km 1.838 km 1.972 I4.2S 0.157 km 1.719 km 1.847 13.88 4197-257 0.174 i. ooi 2.037 14-50 o.i 68 1.838 1.972 I4.25 0.158 1.728 .856 13-95 4203.730 0.175 1.909 2.045 14.56 0.170 .853 1.987 14.36 o.i 60 1-743 .871 14.06 4207.566 0.176 .914 2.050 14-59 0.169 i .841 1-975 14.27 0.161 I-75I .879 I4-I3 4216.136 0.175 .901 2-037 14.50 0.170 .848 .982 I4.32 0-159 1.729 -857 13-97 4220.509 0.177 .917 2.053 14.61 0.170 .845 .979 14.30 0.162 1-755 .883 14.16 4232-887 0.178 .924 2.060 14.66 0.170 .840 974 14.26 0.161 1-743 .871 14.07 4233-328 0.180 944 2.080 14.80 0.173 .870 .004 14.48 0.164 1-773 .901 14.29 4257-SiS 0.179 .921 2-057 14.64 0.172 .848 .982 I4-32 0.165 1.766 894 14.25 4258-47? 0.178 .910 2.046 14.56 0-173 -857 .991 14-39 0.164 1-754 .882 M-iS 4265.418 0.179 915 2.051 H-59 0.173 854 .988 14-37 0.163 1.742 .870 14.06 4266.081 0.179 .914 2.050 14-59 0-175 .874 .008 14.52 0.164 J-752 .880 14-13 4268.915 0.180 .919 2.055 14.63 0.174 .856 .990 14.38 0.164 .879 14.12 4276.836 0.181 .928 2.064 14.69 0.174 -855 .989 14-37 0.164 1-749 -877 14.11 4283.169 0.178 .897 2.033 14.47 o.i74 -854 .988 14-37 0.165 1-759 .887 14.19 4284.838 0.180 1.914 2.050 14-59 0.173 .842 .976 14.28 0.164 1-747 -875 14.10 4287.566 0.180 I-9I3 2.049 14.58 0.174 -852 .986 14-35 . 0.163 1-737 .865 14.02 4288.310 0.180 I-9I3 2.049 14.58 0.174 -8 S I 985 14-34 0.164 1-747 875 14.10 4289.525 0.180 I-9I3 2.049 14.58 0.175 .861 J-995 14.41 0.164 1-747 -875 14.10 4290.377 0.178 1.893 2.029 14.44 0.174 .851 1.985 14-34 0.164 1-747 -875 14.10 4290.542 0.178 1.893 2.029 14.44 0.176 .872 2.006 14.50 0.165 I-756 .884 14.17 4291.630 0.179 1.903 2.039 14-51 0.175 .862 1.996 14-43 0.165 I-756 .884 14.17 = 34^ = 49A 6s!o = 6s!o* , A ,-M, A V + r A r . + J A p v + 1> 1 4196-699 0.125 km I-37I km .486 12.76 0.095 km 1.049 km .138 12.42 0.057 km 0.646 km 0.704 11.83 0.050 km 0.569 km 0.62; 10.53 4197-257 0.125 I-37I .486 12.76 0.095 1.049 .138 12.42 0.058 0.656 0.714 I2.OO 0-053 0.603 0.661 II. IO 4203.73 0.126 1.381 .496 12.84 0.097 1.068 157 12.62 0.058 0.655 0.713 Il.gS 0-055 0.625 0.683 11.47 4207.566 0.126 1-377 492 I2.8l 0.094 1-035 .124 12.26 0.056 0-635 0.693 11.64 0.050 0.567 0.62! 10.50 4216.136 0.126 1-374 .489 12.78 0.096 1-053 .142 12.46 0.059 0.660 0.718 I 2.06 0.050 0-565 0.623 10.47 4220.509 0.129 1.405 .520 13-05 0.097 1. 060 .149 12.53 0.057 0.640 0.698 "73 0.057 0.643 0.701 11.78 4232.887 0.127 1-379 494 12.82 0.097 1-058 -147 12.51 0.058 0.649 0.70; 11.87 0.056 0.630 o.688| 11.56 4233.328 0.129 1-399 SM 12.99 0.096 1.048 137 12.40 0.058 0.649 0.705 11.87 0.052 0.585 0.643 10.80 4257-815 0.130 1.400 515 13.00 0.098 1.063 152 12.57 0.058 0.645 0.703 ii. 81 0.057 0.637 o.6gt 11.68 4258.477 0.129 1.390 505 12.92 0.098 1.063 152 12-57 0-059 0.655 0.713 11.98 0.057 0.636 0.69; 11.66 4265.418 0.129 1.389 504 12.91 0.097 1.047 .136 12-39 0.058 0.643 0.701 11.78 0-053 0.590 0.648 10.88 4266.081 0.131 1.408 523 13.07 0.098 1-057 .146 12.50 0.058 0.643 0.701 11.78 0.054 0.580 0.638 10.72 4268.915 0.130 1-394 509 12-95 0.098 1.056 145 12.49 0.060 0.664 0.722 12.13 0.057 0-635 0.693 11.64 4276.836 0.130 1.390 505 12.92 0.098 1-055 .144 12.48 0.059 0.651 0.70? 11.91 0-055 0.6 1 1 o.66<; 11.24 4283.169 0.131 .400 515 13.00 0.099 1.065 -154 12-59 0.060 0.661 0.71? 12.08 0.060 0.665 0.723 11.15 4284.838 0.130 390 505 12.92 0.099 1.064 153 12.58 0.061 0.650 0.708 11.89 0.055 0.609 0.66; 1 1. 20 4287.566 0.130 390 505 12.92 0.097 1.044 133 12.36 0.058 0.640 0.698 "73 0.057 0.630 0.688 11.56 4288.310 0.131 399 .514 12.99 0.098 1-053 .142 12.46 0.06 1 0.670 0.728 12.23 0.058 0.642 0.700 11.76 4289.525 0.131 399 514 12.99 0.099 1.063 152 12.57 0.060 0.660 0.718 12.06 0.06 1 0.675 0-733 12.31 4290-377 0.129 379 1.494 12.82 0.097 1.043 .132 12.35 0.058 0.640 0.698 11.73 0.057 0.632 o.6ox "-S9 4290.542 0.132 .409 I-524 13.08 0.099 1.063 152 12-57 0.060 0.660 0.718 12.06 0.060 0.665 0.723 12.15 4291.630 0.129 .378 1.493 12.82 0.098 1.053 1.142 12.46 0.060 0.660 0.718 12.06 0.058 0-655 0-713 11.98 * Measured by A. on G. go AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE n. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908 Continued. Plate w 163. 1908, Aug. 26, n h 55 m G. M. T. Measured by L. on T. Distance from Limb i.i mm. Quality, good. p-P sec i) -0-3 o 153-3 24.1 25.0 65.0 17.0 1.046 o-n 78.8 40.1 40.6 494 II.O 1.019 p -19.8 ss-s 55-8 34-2 8.6 I. Oil D 7-i 70.7 70.9 19.1 7-5 1.009 Diameter 168.9 mm 79.0 79.1 10.9 7.2 1.008 Factor 1.013 85.8 85-8 4.2 7-i 1.008 * = * = IOQ - :, A n , + ,, A V " + "j A V v + t 4196.699 0.172 km 1.880 km 2.0l6 14-34 0.170 km 1.859 km 1-993 o 14.40 O.I 60 km 750 km 1.878 14.12 4197-257 0.172 .880 2.016 14-34 0.170 1 1.859 1-993 14.40 0.160 750 1.878 14.12 4203.730 0.173 .889 2.025 14.42 0.173 1-887 2.O2I 14.60 0.162 .768 1.896 14-25 4207.566 0.173 .885 2.O2I 14.38 0.172 1.874 2.008 14-51 0.162 .765 1.893 14-23 4216.136 0.174 .890 2.O26 14.42 0.170 1.849 1.983 14-33 0.162 .762 1.890 14.21 4220.509 0.177 .922 2-058 1465 0.174 1.888 2.022 14.61 0.163 .765 1.893 14.23 4232.887 0.177 .911 2.047 14-57 0.172 1.859 1-993 14.40 0.164 773 1.901 14.29 4233-328 0.176 .901 2.037 14.50 0.174 i. 880 2.014 14-55 0.164 773 1.901 14.29 4257-8i5 0.178 .910 2.046 14-56 0-175 1.879 2.013 14-54 0.166 .782 1.910 14.36 4258-477 0.178 .910 2.046 14.56 0.174 1.869 2.003 14-47 0.165 773 1.901 14.29 4265.418 0.178 .909 2-045 14.56 0.176 1.884 2.018 14.58 0.162 738 1.866 14-03 4266.081 0.179 915 2.051 14.60 0-175 1.874 2.008 14-51 0.165 .762 1.890 14.21 4268.915 0.178 1.904 2.040 14-52 0-175 1.867 2.OOI 14.46 0.165 .761 1.889 14.20 4276.836 0.180 1.917 2-053 14.61 0.175 1-865 1-999 14-45 0.164 750 1.878 14.12 4283.169 0.178 1.896 2.032 14-47 0.175 1.865 1-999 14-45 0.164 750 1.878 14.12 4284.838 0.180 915 2.051 14.60 0.176 1.874 2.008 14-51 0.164 .748 1.876 14.10 4287.566 0.179 905 2.O4I 14-53 0.175 1.864 1.998 14-44 0.165 758 1.886 14.18 4288.310 0.178 895 2.031 14.46 0.175 1.864 1.998 14.44 0.164 .748 1.876 14.10 4289.525 O.I 80 915 2.051 14.60 0.174 1-853 1.987 14.36 0.165 758 1.886 14.18 4290.377 0.179 90S 2.041 14-53 0.175 1.863 1.997 14-43 0.164 .748 1.876 14.10 4290.542 0.180 .914 2.050 14-59 O.I7S 1.863 1.997 14-43 0.165 758 1.886 14.18 4291.630 0.180 1.914 2.050 14-59 0.174 1.852 1.986 14-35 0.164 747 1-875 14.09 = 34^ = 49?4 = 6s!o 0=6SV X A i) ,-M, A ' . + ., A * . + ., A , + ,, I 4196.699 0.131 km .441 km 1-556 13-36 0.094 km 1.038 km 1.127 12.30 0.056 km 0.634 km 0.692 11-63 0.050 km 0.569 km 0.627 o 10.53 4197-257 0.130 430 1-545 13.26 0.094 1.038 1.127 12.30 0.056 0.634 0.692! 11.63 0.052! 0.592 0.650 10.92 4203-730 0.132 443 1-558 13-37 0.096 1.058 1.147 12.52 0.057 0.643 0.701 11.78 0.054! 0.612 0.670 11.26 4207.566 0.132 .440 1-555 13-35 0.096 1.056 I-I45 12.49 0.057 0.642 0.700 11.76 0.052 0.589 0.647 10.87 4216.136 0.131 .429 1-544 13-25 0.095 1.044 I-I33 12.36 0.056 0.630 0.688 11.56 0.052 0.588 0.646 10.85 4220.509 0.132 437 1-552 13-32 0.096 1.052 1.141 12.45 0.059 0.663 0.721 12. II 0.058 0.654 0.712 11.96 4232.887 0.132 435 1-550 13-30 0.099 1.081 1.170 12.77 0.058 0.650 0.70$ 11.89 0.055 0.618 0.676 11.36 4233.328 0-133 .442 1-557 13-36 0.098 1.070 159 12.65 0.058 0.650 0.708 11.89 0.052 0-585 0.643 1080 4257-815 0-133 433 1.548 13.29 0.099 1.074 .163 12.69 0.060 0.666 0.724 12. l6 0-055 0.615 0.673 11.31 4258-477 0.133 433 1.548 13.29 0.098 1.064 153 12.58 0.0581 0.646 0.704 11-83 0.054 0.605 0-633 11.14 4265.418 0.134 435 i-55o 13-30 0.096 1.042 131 12.34 0.060 0.666 0.724 12. l6 0.056 0.624 0.682 11.46 4266.081 0-134 435 i-55o 13-30 0.098 1.057 .146 12.50 0.059 0-653 0.711 11.94 0-055 0.614 0.672 11.29 4268.915 0.135 444 1-559 13-38 0.098 1.056 145 12.49 0.059 0.652 0.7 ic 11.92 0.056 0.623 0.681 11.44 4276.836 0.134 433 1.548 13.29 0.099 1.065 154 12.59 0.060 0.659 0.717 12.04 0-055 0.613 0.671 11.27 4283.169 0.132 .412 1-527 13.10 0.099 1.065 154 12-59 0.058 0.639 0.697 11.71 0.057 0.631 0.689 ii-57 4284.838 0.134 433 1.548 13.29 0.098 1.054 143 12.47 0.060 0.659 0.717 12.04 0.054 0-599 0.657 11.04 4287.566 0.134 433 1.548 13.29 0.100 1-075 1.164 12.70 0.059 0.649 0.707 11.88 0.055 1 0.609 0.667 it. 20 4288.310 0.134 432 1-547 13.28 o.ioi 1.085 1.174 12.81 0.060 0.659 0.717 12.04 0.056 0.619 0.677 "37 4289.525 0.134 431 1.546 13-27 0.099 1.064 I-I53 12.58 0.058 0.639 0.697 11.71 0.056 0.619 0.677 "37 4290.37? 0.133 .420 1-535 13.18 0.098 1-053 1.142 12.46 0.058 0.639 0.697 11.71 0.054 0.598 0.656 1 1. 02 4290.542 0.134 I-43I 1.546 13-27 O.IOI 1.085 1.174 12.81 0.060 0.659 0.717 12.04 0.056 0.619 0.677 n-37 4291.630 0.134 I-43I 1.546 13.27 0.098 1-053 1.142 12.46 0.059 0.649 0.707 11.88 0.057 0.630 0.688 11.56 * Measured by A. on G. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF igo8. TABLE n. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908 Continued. Plate w 164. 1908, Aug. 26, n h 55 m G. M. T. Measured by L. on T. Distance from Limb i.i mm. Quality, good. P-P scc>7 -o-3 1S3-3 24.1 25.0 65.0 17.0 1.046 o-n 78.8 40.1 40.6 49.4 II.O 1.019 p -19.8 55-5 55-8 34-2 8.6 I. Oil D 7.1 70.7 70.9 19.1 7-S 1.009 Diameter 168.9 mm 79.0 79.1 10.9 7.2 1.008 Factor 1.013 85.8 85.8 4.2 7-i 1.008 = 4! 2 0= u*, = 10:1 X A V , + i. A V + A ' , + ., ^196.699 0.169 km .848 km 1.984 14.12 0.169 km 1.858 km 1.992 14.40 0.159 km 739 km 1.867 14.04 4197-257 0.171 .868 2.004 14.26 0.168 1.848 1.982 14-32 0-159 739 1.867 14.04 4203.730 0-173 .885 2.O2I 14.38 0.170 1.853 .987 14-36 o.t6i 752 1.880 14-13 4207.566 0.174 .894 2.030 14-45 0.171 i. 860 994 14.41 O.I 60 741 1.869 14-05 4216.136 0.174 .890 2.O26 14.42 0.170 1.848 .982 14.32 0.159 .729 1.857 13-97 4220.509 0.177 1.920 2.056 14.64 0.173 1.872 .006 14-50 0.162 754 1.882 14-15 4232-887 0.176 1.901 2-037 14.50 0.172 859 993 14.41 0.162 752 1.880 14-13 4233-328 0.176 1.900 . 2.036 14.49 0.172 .859 993 14.41 o.i 60 730 1.858 13.98 4257.8i5 0.178 1.898 2-034 14.48 0.174 .867 2.OOI 14.46 0.162 .741 1.869 14-05 4258.477 0.178 1.898 2.034 14.48 0-174 .867 2.001 14.46 0.163 751 1.879 14.12 4265.418 0.177 1.895 2.031 14.46 0-175 874 2.008 14.51 0.161 .726 1.854 13-94 4266.081 0.179 915 2.051 14.60 O.I7S .874 2.008 14-51 0.163 .742 1.870 14.06 4268.915 0.178 .898 2.034 14.48 0.174 .861 1-995 14.42 0.163 .741 1. 869 14.05 4276.836 0.177 .886 2.O22 14-39 0.174 859 1-993 14.40 0-163 739 1.867 14.04 4283.169 0.178 .896 2.032 14.46 0.175 .863 1-997 14.44 0.164 749 1.877 14.11 4284.838 0.179 904 2.040 14-52 0.174 853 1.987 14.36 0.162 .727 1.855 13-95 4287.566 0.178 .894 2.030 14-45 o.i75 .862 1.996 14-43 0.162 .726 1.854 13-94 4288.310 0.177 .884 2.O2O 14-37 0.174 .852 1.986 14-35 0.165 757 1.885 14.17 4289.525 0.178 893 2.029 14.44 0.176 .872 2.006 14.50 0.164 747 I.875 14.10 4290.377 0.178 1.893 2.O29 14.44 0.174 .852 1.986 14-35 0.164 747 I.875 14.10 4200.542 0.178 1.893 2.O29 14.44 0.176 .872 2.006 14.50 0.164 747 1.875 14.10 4291.630 0.179 1.903 2.039 14-51 0.174 1.852 1.986 14-35 0.165 756 1.884 14.16 = 34!2 = 4*4 = 6 5 :o 4196-699 0.130 .425 1.540 13.22 0.096 1-059 .148 12-53 0.055 0.624 0.682 11.46 4197-257 0.130 425 1-540 13.22 0.096 1.059 .148 12.53 0.057 0.644 0.702 11-79 4203-730 0-133 455 1-570 13.48 0.097 1.064 153 12.58 0.058 0.654 0.712 11.96 4207.566 0.133 454 1.569 13-47 0.097 1.062 151 12.56 0.057 0.644 0.702 11.79 4216.136 0.131 .426 I-S4I 13-23 0.096 1.050 139 12.43 0.056 0.630 0.688 11.56 4220.509 0.132 434 1-549 13-30 0.097 1. 060 .149 12-54 0.058 0.649 0.707 11.88 4232.887 0.133 .441 I-556 13-36 0.096 1.048 137 12.40 0.057 0.638 0.696 11.69 4233-328 0.133 .441 I-556 13-36 0.099 1.081 .170 12.76 0.058 0.648 0.706 11.86 42 C7 8l < O.I36 460 j ~- - I 3-5 2 t^o / "* J OT 7 A t"" I .CCA 4265.418 l OT" 0.135 449 1.564 13-43 0.099 1.072 .161 12.66 0.058 0.643 0.701 11.77 4266.O8I 0.134 436 i-SSi I3-3I 0.098 .063 152 12.57 0.058 0.642 0.700 n-75 4268.915 0.135 444 559 13-38 0.099 .071 .160 12.65 0.058 0.639 0.697 11.71 4276.836 0-135 444 559 13-38 O.IOO .077 .166 12.61 0.059 0.649 0.707 11.88 4283.169 0.134 432 547 13.28 0.100 077 .166 12.61 0.058 0.639 0.697 11.71 4284.838 0.134 432 547 13.28 0.098 056 145 12-49 0.059 0.648 0.706 11.86 4287.566 0-133 431 546 13-27 0.098 -055 .144 12.48 0.058 0.638 0.696 11.69 4288.3IO 0.136 453 .568 13-46 0.098 1-055 .144 12.48 0.058 0.638 0.696 11.69 4289.525 0-135 .442 1-557 13-36 0.099 1.065 154 12.59 0.059 0.648 0.706 11.86 4290.377 O.I3S 1.442 1-557 13-36 0.097 1.044 133 12.36 0.059 0.648 0.706 11.86 4290.542 0.137 1.462 1-577 13-54 O.IOO 1.074 .163 12.69 0.059 0.648 0.706 11.86 4291.630 0.135 1.441 I-S56 13-35 O.IOO 1.074 .163 12.60 0.058 0.638 0.696 11.69 92 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE u. RESULTS FOE INDIVIDUAL PLATES. OBSERVATIONS OF 1908 Continued. Plate w 165. 1908, Aug. 27, 6 h 45 G. M. T. Measured by L. on T. Distance from Limb 1.6 mm. Quality, good. P-P sec'; O.2 O 154.1 24.2 25.2 64.8 17.0 1.046 O-fi 79.6 40.1 40.6 49.4 II.O 1.019 P -20.1 55-6 55-9 34-1 8.6 1. 01 1 D 7.1 70.8 70.9 19.1 7o 1.009 Diameter 168.8 mm 78.3 78.4 u.6 7-3 1.008 Factor 1.019 85.8 85.8 4.2 7-i 1.008 =4% = n6 *-* A It + , A V . + * A V 1 4196.699 0.169 km 1.861 km 1.997 14.22 0.169 km 1.858 km 1.992 14-43 0.158 km 1-738 km 1.867 14.03 4197-257 0.169 1.861 1.997 14.22 o.i 68 1.848 1.982 14.36 0.157 I.736 1.865 14.01 4203.730 0.172 1.887 2.023 14.40 0.170 1.864 1.998 14.48 o.i 60 I-756 1.885 14.16 4207.566 0.173 1.898 2.034 14.48 0.170 1.863 1.997 14.47 o.i 60 1-752 1.881 14-13 4216.136 0-173 883 2.019 14-37 0.171 1.868 2.002 14-52 o.i 60 1-750 1.879 14.11 4220.509 0.176 .923 2.059 14.66 0.170 1.852 1.986 14.40 0.161 1-759 1.888 14.19 4232.887 0.175 90S 2.041 14-53 0.172 1.870 2.OO4 M-53 0.161 1-763 1.892 14.22 4233-328 0.176 915 2-051 14.60 0.171 1. 860 1.994 14-43 0.162 1.762 1.891 14.21 4257-815 0.178 .922 2.058 14.65 0.173 1.870 2.004 14-53 0.163 1.761 1.890 14.20 4258-47? 0.175 .891 2.027 14-43 0.173 1.869 2.003 14.52 0.163 1.761 1.890 14.20 4265.418 0.176 .896 2.032 14.47 0.172 1.854 1.988 14.41 0.163 1-758 1.887 14.18 4266.081 0.176 -895 2.031 14.46 0.173 1-857 I-99I 14-43 0.162 1.748 877 14.10 4268.915 0.178 .916 2-052 14.61 0.174 1.866 2.OOO 14.50 0.163 I-756 -885 14.16 4276.836 0.176 .892 2.028 14.44 0-173 I-8SS 1.989 14.42 0.162 1-739 .868 14.04 4283.169 0.178 .907 2-043 14-54 0.174 1.865 1.999 14.49 0.163 1.748 -877 14.10 4284.838 0.176 .886 2. 02 2 14.40 0.174 1.864 1.998 14.48 0.162 i 737 .866 14.02 4287-566 0.177 .898 2.034 14.48 0.172 1.844 1.978 14-34 0.164 1-757 .886 14.17 4288.310 0.176 -885 2.O2I 14-39 0.172 1.843 1.977 14-33 0.163 1-747 .876 14.09 4289.525 0.178 905 2.O4I 14-53 0.174 1.864 1.998 14.48 0.163 1-747 .876 14.09 4290.37? 0.176 .884 2.020 14-38 0.173 1.851 1.985 14-39 0.163 J-747 1.876 14.09 4290.542 0.177 .894 2.030 14-45 0.172 1.841 J-975 14-31 0.164 1-757 1.886 14.17 4291-630 0.178 90S 2.O4I 14-53 0.173 1.851 1.985 14-39 0.163 1-747 1.876 14.09 = 34?i - 49?4 = 6 4 !8 4196.699 0.131 1.444 -558 13-36 0.095 54 143 12.47 0.054 0.611 0.669 11.15 4197-257 0.130 i -434 548 13.27 0.094 .044 '33 12.36 0.054 0.611 0.669 11.15 4203.730 0.131 1-443 557 13-35 0.094 .042 131 12.34 0-055 0.632 0.690 11.51 4207.566 0-133 1.462 576 13-51 0.095 054 143 12.37 0-055 0.620 0.678 11.31 4216.136 0.132 1.446 .560 13-37 0.094 039 .128 12.31 0-055 0.618 0.676 11.27 4220.509 0.134 .467 .581 J3-47 0.097 .068 157 12.62 0.057 0.636 0.694 "57 4232.887 0.132 .441 555 13-33 0.096 054 143 12.37 0.056 0.625 0.683 4233-328 0.131 431 545 13-25 0.096 054 143 12.37 0.058 0.645 0.703 "73 4257-815 0.133 443 557 13-35 0.097 .058 .147 12.51 0.057 0.628 0.686 11.44 4258.477 0.134 453 .567 13-44 0.098 .068 157 12.62 0.057 0.628 0.686 11.44 4265.418 0.134 438 552 13-30 0.097 052 .141 12.45 0.058 0.637 0.695 "59 4266.081 0.132 .428 542 13.22 0.098 .062 151 12.56 0.058 0-637 0.695 "59 4268.915 0-133 1.438 552 13-30 0.097 .052 .141 12.45 0.058 0-637 0.695 "59 4276.836 0.134 1-443 557 13-35 0.096 .041 -130 12.33 0.057 0.627 0.685 11.42 4283.169 0-134 1.441 555 13-33 0.096 .041 .130 12.33 0.057 0.627 0.685 11.42 4284.838 0.133 1.430 -544 13-24 0.097 .050 139 12-43 0.058 0.636 0.694 "57 4287.566 0.134 1.440 -554 13-32 0.098 .060 .149 12-54 0.057 0.626 0.684 11.40 4288.310 0.135 1.450 -564 13-41 0.098 .060 1.149 12.54 0.058 0.636 0.694 "57 4289.525 0.135 1.450 564 13-41 0.097 1.050 I-I39 12-43 0-059 0.646 0.704 "75 4290-377 0.135 1.449 -563 13.40 0.098 1.059 1.148 12-53 0.058 0.636 0.694 "57 4290.542 0.134 1-439 553 13-31 0.097 1.049 1.138 12.43 0.058 0.636 0.694 "57 4291.630 0.134 1-439 553 13-31 0.098 1.059 1.148 12-53 0.058 0.636 0.694 "57 RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908. 93 TABLE n. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908 Continued. Plate w 166. 1908, Aug. 27, 6 h 45 m G. M. T. Measured by L. on T. Distance from Limb 1.6 mm. Quality, good. p-P sec i? O.2 G IS4- 1 24.2 25.2 64.8 17.0 1.046 o-n 79.6 40.1 40.6 49-4 II.O 1.019 p 20. i 55-6 SS-9 34-1 8.6 I. Oil D 7-i 70.8 70.9 19.1 7-5 1.009 Diameter 168.8 mm 78.3 78.4 n.6 7-3 1.008 Factor 1.019 85.8 85.8 4.2 7-i 1.008 *- 4!* *- M = * A 11 ,-M, * A V . + ,, a A V . + ,, b 4196.699 0.172 km 1.892 km 2.028 14.44 0.168 km 1.847 km 1.981 14.36 0.158 km -738 ktt 1.867 14-03 4197-257 0.174 1.912 2.048 14-58 0.168 1.847 1.981 14-36 0.158 -738 .867 14.03 4203.730 0-173 1.898 2-034 14.48 0.169 1-853 1.987 14.40 0.159 745 .874 14.08 4207.566 0.176 1.930 2.066 14.71 0.169 1.852 1.986 14-39 o.i 60 751 .880 14.12 4216.136 0.176 I-925 2.061 14.67 o.i 68 I-837 I.97I 14.29 o.i 60 749 .878 14.10 4220.509 0.178 1-944 2.080 14.81 0.171 i. 86 1 1-995 14.46 o.i 60 .748 .877 14.09 4232.887 0.178 1.936 2.072 14-75 0.169 1.839 1-973 14.30 0.161 752 .881 14-13 4233-328 0.178 1.936 2.072 14-75 0.172 1.869 2.003 14-52 0.162 .761 .890 14.20 4257-815 0.179 1-933 2.069 14-73 0.171 1.849 1-983 14-37 0.162 750 .879 14.11 4258.477 0.177 I-9I3 2.049 14-59 0-173 1.868 2. OO2 14-51 0.162 750 .879 14.11 4265.418 0.177 1-907 2.043 14-55 0-173 1.863 1-997 14.47 0.161 737 .866 14.02 4266.081 0.178 1.916 2.052 14.62 0.172 1.846 1.980 14-35 0.162 1-747 .876 14.09 4268.915 0.178 1.916 2.052 14.62 0.172 1-845 1-979 14-34 0.162 1-745 .874 14-07 4276.836 0.178 I-9I3 2.049 14-59 0.173 1.854 1.988 14.41 0.161 1-729 .858 13.96 4283.169 0.177 1.898 2.034 14.48 0.172 1.844 1.978 14-33 0.162 1-738 .867 14-03 4284.838 0.176 1.886 2.O22 H-39 0.171 1-833 1.967 14.26 0.162 1-737 .866 14.02 4287.566 0.177 1.898 2.034 14.48 0.173 1-853 1.987 14.40 0.162 737 .866 14.02 4288.310 0.179 1.916 2.052 14.61 0.172 1.842 1.976 14.32 0.163 747 .876 14.09 4289.525 0.178 1.906 2.042 14-54 0.174 1-863 1-997 14-47 0.163 747 .876 14.09 4290.377 0.178 1-905 2.041 14-53 0-173 1.851 1.985 14-39 0.162 737 .866 14.02 4290.542 0.179 1-915 2.O5I 14.60 0.172 1.841 1-975 14.28 0.163 747 1.876 14.09 4291.630 0.176 1-885 2.021 14-38 0.173 1.851 1.985 14-39 0.164 .756 1.885 H-iS = 34U = 4*4 = 64:8 - 4196.699 0.130 1-434 1.548 13.27 0.096 1.065 154 12-59 0-055 0.622 0.680 "34 4197.257 0.129 .424 1-538 13-19 0.094 1.045 134 12.37 0.054 0.612 0.670 11.17 4203.730 0.132 451 1-565 13-42 0.096 1.064 153 12.58 0.056 0.628 0.686 11.42 4207.566 0.131 .441 1-555 13-33 0.098 1.086 175 12.82 0.057 0.637 0.695 11.58 4216.136 0.130 .426 1.540 13.20 0.096 1. 060 .149 12.54 0.057 0.636 0.694 11-57 4220.509 0.134 .468 1.582 13-57 0.096 1.059 .148 12.52 0.058 0.646 0.704 "74 4232.887 0-133 451 1-565 13-42 0.097 1.065 154 12.59 0.057 0.635 0.693 11.56 4233.328 0-134 .462 I-576 13-51 0.096 1-055 144 12.48 0.056 0.625 0.683 11.38 4257-815 0-134 453 1-567 13-44 0.098 1.069 .158 12.63 0.058 0.638 0.696 11-59 4258.477 0.136 474 1.588 13.62 0.098 1.069 .158 12.63 0.058 0.638 0.696 "59 4265.418 0-135 458 1-572 13-47 0.097 1-053 .142 12.46 0.057 0.627 0.685 11.40 4266.081 0-134 .448 1.562 I3-38 0.097 1-053 .142 12.46 0.058 0.637 0.695 11.58 4268.915 0-135 -458 1-572 13-47 0.098 1.063 152 12.57 0.058 0.637 0.695 11.58 4276.836 0.134 443 1-557 13-34 0.098 1.062 IS' 12.56 0.057 0.627 0.685 11.40 4283.169 0.134 .441 1-555 13-33 0.098 1.062 151 12.56 0.058 0.637 0.695 11.58 4284.838 0-135 451 1-565 13-42 0.098 1.061 -ISO 12-55 0.059 0.646 0.704 11.74 4287.566 0-134 .440 1-554 13-32 0.098 1.061 .150 12-55 0.057 0.626 0.684 "39 4288.310 0.134 440 1-554 13-32 0.097 1.051 .140 12-44 0.058 0.636 0.694 "57 4289.525 0-135 1.450 1-564 13-41 0.098 1.061 ISO 12-55 0.059 0.646 0.704 n-74 4290.377 0.134 1-439 1-553 I3-3I 0.098 i. 060 .149 12.54 0.057 0.626 0.684 "39 4290.542 0.134 1-439 1-553 I3-3I 0.098 i. 060 149 12.54 0.058 0.636 0.694 11-57 4291.630 0-135 1-449 1-563 13-40 0.009 1.070 159 12.65 0.058 0.636 0.694 11-57 94 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE n. RESULTS TOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908 -Continued. Plates o> 179 and a 180. 1908, Sept. 30, n h 40 G. M. T. ^Measured by L. on T. Distance from Limb i.o mm. Quality, good. p P -w T} secy 29.2 29.9 60.1 13.5 1.028 O 187.4 o-n 112.9 p -26.2 D 6.7 Diameter 170.6 mm Factor 1.012 X = 6oti t> = 6o!i = 60! I = 6oi A 3 v + v 1 * A + , 1 A I) + , J A V P + Bj km km km km km km km km 4196.699 0.070 0-779 0.852 12.14 0.070 0-779 0.852 12.14 0.064 0.718 0.791 11.27 0.065 0.728 0.801 11.41 4197-257 0.070 0.779 0.852 12.14 0.070 0.779 0.852 12.14 0.065 0.728 0.801 11.41 0.065 0.728 0.801 11.41 4203.730 0.070 0.778 0.851 12.12 0.070' 0.779 0.852 12.14 0.065 0.726 0.799 "-38 0.065 0.727 0.800 11.40 4207.566 0.072 0.797 0.870 12.39 0.071 0.787 0.860 12.25 0.065 0.725 0.798 u-37 0.066 0-735 0.808 11.51 4216.136 0.071 0.786 0.859 12.24 0.070 0.776 0.849 12.09 0.064 0.714 0.787 II. 21 0.065 0.723 0.796 n-34 4220.509 0.072 Q-795 0.868 12.36 0.072 0.795 0.868 12.37 0.066 0.732 0.805 11.47 0.067 0.741 0.814 "59 4232.887 0.072 0-793 0.866 12-33 0.072 0.794 0.867 12-35 0.065 0.720 0-793 11.29 0.065 0.720 0-793 11.29 4233-328 0.072 0-793 0.866 12-33 0.073 0.803 0.876 12.48 0.066 0.730 0.803 11.44 0.066 0.730 0.803 11.44 4257-815 0.074 0.808 0.881 12-55 0.074 0.808 0.881 12-55 0.068 0.746 0.819 11.67 0.067 0-735 0.808 11.51 4258.477 0.072 0.788 0.861 12.26 0.072 0.788 0.86 1 12.26 0.067 0.736 0.809 11.52 0.067 0-735 0.808 11.51 4265.418 0.072 0.787 0.860 12.25 0.073 0.798 0.871 12.40 0.068 0.744 0.817 11.64 0.067 0.734 0.807 11.49 4266.081 0.073 0-797 0.870 12.39 0.074 0.808 0.881 12.55 0.068 0.744 0.817 11.64 0.069 0-754 0.827 11.78 4268.915 0.072 0.787 0.860 12.25 0.074 0.807 0.880 12.53 0.068 0-744 0.817 11.64 0.067 0-734 0.807 11.49 4276.836 0.074 0.805 0.878 12.51 0.074 0.806 0.879 12.52 0.067 0-733 0.806 11.48 0.068 0-743 0.816 11.62 4283.169 0.072 0.783 0.856 12.19 0.073 0.794 0.867 12-35 0.067 0.732 0.805 11.47 0.067 0-733 0.806 11.48 4284.838 0.072 0.783 0.856 12.19 0.074 0.804 0.877 12.49 0.068 0.742 0.815 11.61 0.067 0-733 0.806 11.48 4287.566 0.073 0.792 0.865 12.35 0.074 0.803 0.876 12.48 0.068 0.742 0.815 ii. 61 0.068 0-742 0.815 II.OI 4288.310 0.074 0.802 0.875 12.47 0.073 0-793 0.866 12.34 0.068 0.742 0.815 11.61 0.067 0.732 0.805 11.47 4289.525 0.074 0.802 0.875 12.47 0.074 0.803 0.876 12.48 0.069 0.752 0.825 "75 0.068 0.742 0.815 ii. 61 4290.377 0.073 0.792 0.865 12.32 0.072 0.783 0.856 12.20 0.068 0.742 0.815 11.61 0.067 0.732 0.805 11.47 4290.542 0.073! 0.792 0.865 12.32 0.073 0-793 0.866 12-34 0.067 0.730 0.803 11.44 0.069 0.752 0.8251 11.75 4291.630 0.074 0.802 0.875 12.47 0.073 0-793 0.866 12.34 0.068 0.740 0-813 n-59 0.071 0.772 0.845 12.04 Plate w 182. 1908, Oct. 9, n h o m G. M. T. Measured by L. on T. Distance from Limb i.o mm. Quality, good. p P TT = IIO = n?o = iQ?o = 33?9 A A V fl + Hj A 1! + *, J A 11 + , { A a + i km km km km km km km km 4196.699 0.169 1.843 1.981 14-33 0.169 1.843 1.981 14-33 0-157 .711 1-845 13.85 0.125 1-365 1.485 12.70 4197-257 0.170 1.852 1.990 14-39 0.170 1.852 1.590 14-39 0.158 .721 1.855 13.93 0.125 .365 I.48S 12.70 4203.730 0.171 1.861 1.999 14.46 0.172 1.872 2.009 14-53 0.157 70S 1.839 13.81 0.127 384 1.504 12.86 4207.566 0.172 1.869 2.007 14-52 0.172 1.865 2.OO2 14.48 o.i 60 731 1.865 14.00 0.127 382 1.502 12.85 4216.136 0.172 1. 860 1.998 14-45 0.171 1.852 1.990 14-39 0.159 .718 1.852 13.91 0.126 .367 1.487 12.72 4220.509 0.172 1.858 1.996 14.44 0.172 1.856 1.994 14.42 0.160 .725 1. 860 13-97 0.126 366 1.486 12.71 4232.887 0.173 1-865 2.003 14.49 0.173 1.863 2.OOI : 4-47 o.i 60 .724 1.859 13.96 0.128 .381 I.50I 12.84 4233-328 0.173 1.865 2.003 14.49 0.172 1.853 I.99I 14.40 0.161 734 1.868 14.03 0.126 360 1.480 12.66 4257-815 0.175 1.874 2.OI2 14-55 0.172 1.843 1.981 14-33 o.i 60 .712 1.846 13.86 0.128 372 1.492 12.77 4258-477 0.174 1.863 2.OOI 14-47 0.174 1.862 2.000 14.46 0.160 .712 1.846 13.86 0.127 362 1.482 12.68 4265.418 0.174 1.859 1-997 14.44 0-173 1.848 1.986 14-36 0-159 1.697 1.831 13-75 0.127 .361 1.481 12.67 4266.081 0.174 1.859 1.997 14.44 0.174 1.859 1.997 14.44 0.161 1-715 1.849 13-88 0.129 .380 1.500 12.83 4268.915 0.174 1-855 1-993 14.41 0.174 1.856 1.994 14.42 0.161 1.714 1.848 13.88 0.126 347 1.467 12-55 4276.836 0.173 1.843 1.981 14-33 0.173 I-843 1.981 14-33 o.iS9 1.693 1.827 13.72 0.126 345 I-465 12.53 4283.169 0.173 1-838 1.976 14.29 0.174 1.848 1.986 14.36 0-159 1.689 1.823 13.69 0.127 352 1.472 12-59 4284.838 0.174 1.848 1.986 14.36 0.173 1.837 1-975 14.28 0.160 1.699 1-833 13.76 0.127 352 1.472 12.59 4287.566 0.174 1.847 1.985 14-35 O.I7S I-857 '995 14.42 0.160 1.698 1.832 13.76 0.127 351 1.471 12.58 4288.310 0.174 1.847 1.985 14.35 0.174 1.847 1.985 14-35 o.i 60 1.698 1.832 13.76 0.127 351 1.471 12.58 4289.525 0.173 1.836 1-974 14.28 0.175 1.856 1.994 14.41 o.i 60 1.698 1-832 13.76 0.128 .361 1.481 12.67 4290.377 0.173 1.836 1-974 14.28 0-175 1.856 1.994 14.41 0.159 1.688 1.822 13.68 0.128 .361 1.481 12.67 4290.542 0.174 1.846 1.984 14-35 0-175 1.856 1.994 14.41 0.159 1.688 1.822 13.68 0.128 .361 1.481 12.67 4291.630 0.172 1-825 1.963 14.20 0-175 1.856 1.994 14.41 0-157 1.718 1.852 13.91 0.128 .361 1.481 12.67 RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908. 95 TABLE it. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS OF 1908 Continued. Plate w 183. 1908, Oct. 9, n h o m G. M. T. Measured by L. on T. Distance from Limb i.o mm. Quality, good. P-F secv O.I G 196.2 55-9 56.1 33-9 7-4 i. 008 o-n 121.7 70.9 71.0 19.0 6-5 i. 006 P -26.5 78.9 79.0 II.O 6-3 i. 006 D 6.1 Diameter 172.6 mm Factor 1.012 = i.?o = .* = 19*0 = .0!0 A V . + ,, 8 A D + ,, A ii + r, 1 A V * + ., 4196.699 0.170 km 1-851 km 1.989 o 14.38 0.170 km .851 km 1.989 14-38 0.158 km .722 km 1.856 13-94 0.158 km 1.722 km .856 13-94 4197-257 0.169 1.841 1-979 14-31 0.170 .851 1.989 14.38 0.158 .722 1.856 13-94 0.158 1.722 -856 13-94 4203.730 0.172 1.870 2.008 14-52 0.173 .878 2.016 14.58 o.i 60 741 I-875 14.08 0.159 1.729 .863 13-99 4207.566 0.171 1.854 1-992 14.41 0.171 8S4 1-992 14.41 0.161 749 1.883 14.14 o.i 60 1.738 .872 14.06 4216.136 0.171 1.851 1.989 14-38 0.171 .851 1.989 14-38 0.159 .726 1.860 13-97 o.i 60 1-734 .868 14.03 4220.509 0.172 I.8S5 1-993 14.41 0.174 .878 2.016 14.58 o.i 60 734 1.868 14-03 o.i 60 1-732 .866 14.01 4232.887 0.171 1.842 1.980 14-32 0.174 .875 2-013 H-S 6 0.162 745 1.879 14.11 o.i 60 1-725 859 13.96 4233-328 0.172 1.852 1.990 14-39 0.173 .864 2.OO2 14.48 0.161 735 1.869 14-03 0.161 1-735 .869 14-03 4257-8IS 0.174 1.862 2.000 14-46 0.174 .861 1-999 14.46 0.164 755 1.889 14.18 0.162 1-734 .868 14.02 4258.477 0.174 I.86I 1-999 14.46 0.174 .861 1-999 14.46 0.161 724 1.858 13-95 0.161 1-724 -858 13-95 4265.418 0.174 I.857 1-995 14-43 0.174 .857 1-995 14-43 0.161 .721 1-855 13-93 0.161 1.724 .858 13-95 4266.081 0.175 1.867 2.005 14-50 0-173 .846 1.984 14-45 0.162 -730 1.864 14.00 0.162 1-734 .868 14.02 4268.915 0.174 1.855 1-993 14.41 0.174 .855 1-993 14.41 0.162 729 1.863 13-99 0.162 1.729 -863 13-99 4276.836 0.174 1.862 2.OOO 14.46 0-175 .863 2.001 14-47 0.162 .726 i. 860 13-97 0.161 1.716 .850 13.90 4283.169 0.174 1.848 1.986 14-37 0.176 .867 2.OO5 14.50 0-163 731 1.865 14.00 0.162 1.721 .855 13-93 4284.838 0.174 1.847 1.985 14-36 0.175 857 995 14-43 0.162 .721 1-855 13-93 0.162 .721 855 13-93 4287.566 0.174 1.846 1.984 14-35 0.175 -856 994 14.42 0.163 731 1.865 14.00 0.161 .710 .844 13-85 4288.310 0.174 1.846 1.984 14-35 0.174 .846 984 14-35 0.162 .720 1-854 13.92 0.162 .720 854 13-92 4289.525 0.175 I.855 1-993 14.41 0.175 -855 -993 14.41 0.162 719 1-853 13-91 0.162 -719 .853 13.92 4290.377 0.173 I.835 1-973 14-27 0-175 -855 993 14.41 0.162 .719 1-853 13-91 0.161 .709 1.843 13-84 4290.542 0.175 1.855 1-993 14.41 0.176 .865 2.003 14.48 0.164 739 1-873 14.06 0.162 .719 1-853 13-91 4291.630 0.175 1.855 1-993 14.41 0-7I5 855 1-993 14.41 0.162 719 1-853 13-91 0.162 .719 I.8S3 13-91 = igo = 33!, = 33^9 = 33 9 4196.699 0.159 1.732 1.866 14.01 0.131 431 551 13-27 0.130 1.420 1.540 13-17 0.129 1.411 531 13.10 4197-257 0.159 1-732 1.866 14.01 0.131 431 551 13.27 0.130 1.420 1-540 13-17 0.130 1.420 540 13-17 4203.730 o.i 60 1-741 1-875 14.08 0.132 439 559 13-33 0.132 1.438 I.558 13-33 0.131 1.428 .548 13-24 4207.566 o.i 60 1.738 1.872 14.06 0.132 437 557 13-32 0.132 1-437 1-557 13-32 0.131 1-425 545 13.22 4216.136 o.i 60 1-735 1.869 14.03 0.131 .419 539 13.16 0.130 .416 I-536 13-14 0.131 1-423 543 13.20 4220.509 0.160 1.732 1.866 14.01 0.131 .418 -538 13.16 0.132 432 1-552 13-28 0.132 1-432 -552 13.28 4232-887 0.161 1-736 1.870 14.04 0.132 .426 546 13.22 o.i34 .446 1.566 13-39 0.132 1-429 549 13-25 4233-328 o.i 60 1-724 1.858 13-95 0.132 .426 546 13.22 0.133 436 1.556 13-31 0.134 1-447 .567 13-40 4257-8I5 0.161 1.724 1-858 13-95 0.135 449 569 13-42 0-I3S 449 1.569 13-41 0.134 1-437 557 13-32 4258.47? 0.162 1-734 1.868 14.03 0.134 438 -558 13-33 0-134 438 I.558 13-33 0.132 1.417 537 13-15 4265.418 0.161 1.721 1-855 13-93 0.132 413 533 13-11 0.133 .424 1-544 13.21 0.133 1.424 544 13.21 4266.081 0.162 i-73i 1.865 14.00 0.133 423 543 13.20 0.134 434 1-554 13.29 0.133 1-424 544 13-21 4268.915 0.162 1.727 1.861 13-97 0.134 432 552 13.28 0.135 444 1-564 13-38 0-134 1-432 552 13.27 4276.836 0.116 1.849 13-89 0.134 431 551 13-27 0.134 431 i-SSi 13-27 0.133 1.420 540 13-17 4283.169 0.126 1.721 I-85S 13-93 0.134 427 547 13-23 0.134 .426 I-546 13.22 o.i33 1.417 537 13-15 4284.838 0.161 1.711 1.845 13-85 0.134 .427 547 13-23 0.134 .426 1.546 13.22 0.132 1.407 .527 13-06 4287.566 0.161 1.711 1-845 13-85 0-134 .426 546 13.22 0.133 415 1-535 13-13 0.134 1-429 549 13-25 4288.310 0.162 1.720 1.854 13-92 0.134 425 545 13.22 0.133 415 1-535 I3-I3 0-133 1.419 539 13.16 4289.525 0.162 1-719 1-853 13-91 0-135 435 555 13-30 0-133 415 1-535 13-13 0.134 1.429 549 13-25 4290.377 0.161 1.709 1-843 13-84 0.135 435 555 13-30 0-135 435 1-555 I3-30 0-133 1-419 539 13.16 4290.542 0.162 1-7I9 1-853 13-91 0.134 425 545 13.22 0.135 435 1-555 13-30 0-134 1.429 1-549 13-25 4291.630 0.163 1.729 1-863 13-99 0.135 I-43S 555 13-30 0.134 425 1-545 13.22 0.136 1.446 1.566 13-39 96 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE n. RESULTS FOR INDIVIDUAL PLATES. OBSERVATIONS or 1908 -Continued. Plate w 184. 1908, Oct. 22, 6 h 30'" G. M. T. Measured by L. on T. Distance from Limb 1.3 mm. Quality, good. P-f sec*? o.o 209.0 24.0 24-5 6S.5 12.5 1.024 O-Q I34-S 29-3 29.7 60.3 10.5 1.017 P -25-9 39-7 40.0 50.0 8.1 I.OIO D 5-i 86.0 86.0 4.0 5-2 1.004 Diameter 171.2 mm Factor 1.015 \ *-* = 5oo = So!o A A V . + f A ' . + ,, s A , + 4196.699 0.176 km 1.920 km 2.060 14.66 0.092 km I.OIO km .109 o 12.25 0.093 km I.O2O km I.II9 12.36 4197-257 0.176 1.920 2.060 14.66 0.092 I.OIO .109 12.25 0.093 I.O2O 1.119 12.36 4203.730 0.176 I-9I5 2-055 14.62 0.093 1.017 .116 12-33 0.094 1.030 1.129 12.47 4207.566 0.177 1.924 2.064 14.69 0.093 1.015 .114 12.30 0.094 1.028 1.127 12.45 4216.136 0-177 1.919 2.059 14-65 0.092 1.004 103 12.18 0.094 1.023 1. 122 12.39 4220.509 0.178 1.928 2.068 14-72 0.094 1.023 .122 12.39 0.095 1.032 1.131 12.49 4232-887 0.178 .921 2.061 14.67 0.094 1. 020 .119 12.36 0.094 1.020 I.II9 12.36 4233-328 0.180 .941 2.081 14.81 0.095 1.030 .129 12.47 0.095 1.030 I.I29 12.47 4257-815 0.180 .928 2.068 14.72 0.094 1.013 .112 12.28 0.097 1.043 1.142 I2.6l 4258-477 0.179 .918 2.058 14-65 0.095 1.023 .122 12.39 0.095 I.O22 1. 121 12.38 4265.418 0.179 .914 2-054 14.62 0.094 I.OI2 .III 12.27 0.094 I .Oil i. no 12.26 4266.081 0.181 934 2.074 14.76 0.096 1.032 131 12.49 0.095 1. 02 I 1. 1 20 12.37 4268.915 0.180 .921 2.061 14.67 0.094 I.OO9 .108 12.24 0.096 1.030 1.129 12-47 4276.836 0.180 .919 2.059 14-65 0.094 1.008 .107 12.23 0.096 I.O29 1.128 12.46 4283.169 0.180 913 2-053 14.61 0.095 1.016 "5 12.32 0.097 1.036 I-I35 12-54 4284.838 0.180 913 2-053 14.61 0.095 1.016 .115 12.32 0.097 1.036 ''35 12-54 4287.566 0.180 .912 2.052 14.60 0.094 1.005 .104 12.19 0.096 I.O26 1.125 12-43 4288.310 0.179 .902 2.042 14-53 0.095 1.015 .114 12.30 0.097 1.036 I-I35 12.54 4289.525 0.180 .912 2.052 14.60 0.097 1.036 135 12.54 0.098 1.046 I-I45 12.65 4290.377 0.180 .912 2.052 14.60 0.094 1.005 1.104 12.19 0.096 1-025 1.124 12.41 4290.542 0.180 .912 2.052 14.60 0.095 1.015 1.114 12.30 0.098 1.046 I-I45 12.65 4291.630 0.181 .922 2.062 14.67 0.095 1.015 1.114 12.30 0.097 1.035 I-I34 12.52 \ , = 60:3 = 6o3 * = 6 5 : s * = 6 5!S A A V , + ., A D M-i 1 A V . + ,, A V . + ., s 4196.699 0.065 km 0.719 km 0.799 "45 0.066 km 0.729 km 0.805 iJ-59 0-053 km 0.589 km 0.657 11.25 0-053 km 0.588 km 0.656 11.23 4I97-257 0.066 0.729 0.805 "59 0.066 0.729 0.805 "59 0.054 0.600 0.668 11.44 0-053 0.588 0.656 11.23 4203.730 0.068 0.750 0.830 11.89 0.067 0-739 0.815 11.74 0.053 0.588 0.656 n-57 0.054 0.598 0.666 11.40 4207.566 0.068 0.749 0.825 11.88 0.067 0-739 0.815 11.74 0.054 0.598 0.666 11.40 0.054 0-597 0.665 11.38 42l6.I36 0.067 0.738 O.SlS 11.72 0.066 0.728 0.808 11.58 0.053 0.586 0.654 n. 20 0.053 0.585 0-653 11.18 422O.5O9 O.O68 0.746 0.826 11.84 0.068 0.746 0.82^ 11.84 0-053 0.584 0-652 ii. 16 0-053 0.584 0.652 ii. 16 4232.887 0.069 0-754 0.834 "95 0.067 0-734 11.66 0-055 0.605 0.673 11.52 0-053 0.583 0.651 11.14 4233-328 0.068 0-744 0.824 11.81 0.070 0.764 0.84/ 12.09 0.054 0.593 0.66 1 11.32 0.054 0-593 0.661 11.32 4257-8I5 0.068 0-739 o.Sic 11.74 0.070 0.758 0.838 12.01 0.055 0.600 0.668 11.44 0.055 0.601 0.669 "45 4258.477 ! 0.068 0-739 0.819 11.74 0.069 0.748 0.828 11.86 0-055 0.600 0.668 n-44 0.055 0.601 0.669 11-45 4265.418 0.069 0.748 0.828 11.86 0.070 0.758 0.838 12.01 0.053 0.578 0.646 1 1. 06 0.055 0.600 0.668 11.44 4266.081 0.069 0.748 0.828 11.86 0.069 0.748 0.828 11.86 0.057 0.622 0.690 11.81 0.056 0.610 0.678 n. 61 4268.915 0.069 0.746 0.826 11.84 0.070 0-757 0-837 11.99 0.056 0.610 0.678 1 1. 6 1 0.056 0.609 0.677 "59 4276.836 0.068 0-734 O.8l = 4! = s! A V + , * A o II + D, 1 A 11 V +1> i 4196.699 0.176 km .920 km 2.060 14.66 0.176 km 1.920 km 2.060 14.66 0.091 km I.OOO km 1.099 12.14 4197-257 0.176 .920 2.060 14.66 0.176 1.920 2.060 14.66 0.092 I.OIO 1.109 12.25 4203.730 0.177 .926 2.066 14.70 0.176 I.9I5 2-055 14.62 0.092 I.OIO 1.109 12.25 4207.566 0.177 924 2.064 I4-69 0.177 1.921 2.061 14.67 0.091 0.997 1.096 12. IO 4216.136 0.177 .921 2.061 14.67 0.176 1.909 2.049 14-58 0.093 015 I.II4 12.30 4220.509 0.178 .928 2.068 14.72 0.177 1.917 2.057 14.64 0.094 .021 .120 12-37 4232.887 0.178 .919 2.059 14.65 0.178 1.920 2.o6o 14.66 0.093 .009 .108 12.24 4233-328 0.177 .909 2.049 14.58 0.178 1.920 2.060 14.66 0.093 .009 .108 12.24 4257-815 0.179 .918 2-058 14.65 0.181 1.938 2.078 14-79 0.093 .OO2 .IOI 12. 16 4258.477 0.179 1.918 2.058 I4-6S 0.180 1.928 2.068 14-72 0.093 .002 .101 12. l6 4265.418 0.178 1.901 2.041 I4-52 0.181 1.922 2.062 14.67 0.093 .000 .099 12.14 4266.081 O.I 80 1.921 2.061 14.67 0.182 1.942 2.082 14.82 0.094 .010 .109 12.25 4268.915 0.180 1.920 2.060 14.66 0.180 1.921 2.061 14.67 0.094 .009 .108 12.24 4276.836 0.178 1.898 2.038 I4-5I 0.179 1.909 2.049 14.58 0-093 0.998 097 12.12 4283.169 0.180 1.916 2.056 14.63 0.182 1.936 2.076 14-77 0.094 1.005 .104 12.19 4284.838 0.180 1.916 2.056 14.63 0.180 I-9IS 2-055 14.62 0.093 0-995 094 I 2. 08 4287.566 0.179 1.906 2.046 14.56 0.180 1.914 2-054 14.62 0.094 1.005 .104 12.19 4288.310 0.181 I-925 2.065 14.69 0.180 I-9I3 2-053 14.61 0.092 0.984 083 11.96 4289.525 0.179 1.904 2.044 14-55 0.182 1-933 2.073 14-75 0.093 0.994 093 I2.O7 4290.377 0.180 I-9I3 2-053 14.61 0.181 1.922 2.062 14.67 0.093 0.994 093 12.07 4290.542 0.180 1.912 2.052 14.60 0.182 1.932 2.072 14-74 0.094 1.004 1.103 12.18 4291.630 0.182 1.932 2.072 '4-74 0.182 1.932 2.072 14-74 0.093 0.994 1.093 12.07 = 65^5 = 6s!s 4196.699 0.052 0.580 0.648 11.09 0.050 0-556 0.624 10.68 4197-257 0.053 0.590 0.658 11.26 0.050 0.556 0.624 10.68 4203.730 0.052 0.580 0.648 11.09 0.052 0-577 0.645 11.04 4207.566 0.052 0-577 0.645 11.04 0.050 0-553 0.621 10.63 4216.136 0.052 0-575 0.643 II. OI 0.049 0.540 0.608 10.41 4220.509 0.053 0-585 0.653 ii. 18 0.052 0-574 0.642 10.99 4232.887 0.052 0-573 0.641 10.97 0.052 0-572 0.640 10.96 4233-328 0-053 0-583 0.651 11.14 0.052 0.572 0.640 10.96 4257-815 0.054 0.590 0.658 11.26 0.052 0.566 0.634 10.85 4258.477 0.053 0.580 0.648 11.09 0.051 0-555 0.623 10.66 4265.418 0.054 0.589 0.657 11.25 0.051 0-554 0.622 10.65 4266.081 0.054 0.589 0.657 11.25 0.052 0-565 0-633 10.84 4268.915 0.054 0.588 0.656 11.23 0.052 0-565 0.633 10.84 4276.836 0.054 0.587 0-655 II. 21 0.052 0.564 0.632 10.82 4283.169 0.052 0.566 0.634 10.85 0.052 0.562 0.630 10.78 4284.838 0.054 0.586 0.654 1 1. 2O 0.052 0.562 0.630 10.78 4287.566 0.054 0.585 0-653 II.I8 0.050 0-544 0.6 1 2 10.48 4288.310 0-055 0.596 0.664 "37 0.052 0.562 0.630 10.78 4289.525 0.053 0-575 0.643 II.OI 0.052 0.561 0.629 10.77 4290.377 0.054 0-585 0-653 ii. 18 0.051 o.SSO 0.618 10.58 4290.542 0.052 0-565 0.633 10.84 0.052 0.561 0.629 10.77 4291.630 0.053 0-575 0.643 II.OI 0.051 0-550 0.618 10.58 MEAN RESULTS FOR EACH PLATE FROM ALL LINES. OBSERVATIONS OF 1908. 99 The results for the individual plates are summarized in Tables 12, 13, and 14, which are identical in form with Tables 5, 6, and 7 for the 1906-1907 observations. TABLE 12. MEAN RESULTS FOR EACH PLATE FROM ALL LINES. OBSERVATIONS OF 1908. PLATE No. DATE. No. OF LINES. i + j f PLATE No. DATE. No. OF LINES. + , 1908 km o 1908 o km V + V 1 { PLATE No. DATE. No. or LINES. + r, 1 1908 km 1908 km u 136 June ii 22 -o-S 2.047 14-53 u 165 Aug. 27 22 4-2 2.032 14.47 4-5 1.981 14.11 n.6 1.992 14-43 I9-S 1.847 13-91 19.1 1. 880 14.12 34-5 i-5Si 13-36 34-1 1-557 13-35 49-5 1.158 12.66 49-4 1.142 12.46 64-S 0.656 10.81 64.8 0.688 11.48 79-5 0.266 10.36 w 146 Aug. S 22 0-3 2.028 14.40 w 166 Aug. 27 22 4-2 2.049 14.58 15-2 1-934 14-23 n.6 1.984 I 4 . 3 8 30.1 1.658 13.60 19.1 1.874 14.07 45-5 1.265 12. 8l 34-1 1.561 I3-38 60.7 0.682 10.97 49-4 1.150 12-55 75-4 0.405 "35 64.8 0.691 11.52 u 147 Aug. 5 22 0-3 2.052 14-57 w 179 Sept. 30 22 60. 1 0.865 12.32 15-2 1-959 14.42 60. 1 0.867 12-35 30.1 1.686 13-85 45-5 1.269 12.86 60.7 0.781 "34 75-4 0.401 11.30 w 148 Aug. 5 22 -3 2.056 14.60 w 180 Sept. 30 22 60. 1 0.808 11.51 15-2 1-959 14.41 60. 1 0.810 "S3 30-1 1.688 13-85 35-5 1.265 12.81 60.7 0.798 "59 754 0.403 11.36 <"> 151 Aug. 6 22 -o-3 2.062 14.64 <> 182 Oct. 9 22 II.O 1.990 14-39 -0-3 2.060 14-63 II.O 1.992 14.40 14.6 1-952 14-32 19.0 1.843 13-84 44.6 1.270 12.66 33-9 1.483 12.69 59-8 0.809 11.42 74-9 0.415 11.31 < 161 Aug. 26 22 4-2 2.044 14-55 <> 183 Oct. 9 22 II.O 1.991 14.40 10.9 1.989 14.38 II.O 1.997 14.44 19.1 1.886 14.18 19.0 1.864 14.00 34-2 1-547 13.27 19.0 1.858 13-95 49-4 1.080 11.78 19.0 1.859 13.96 65.0 0.631 10.60 33-9 1-549 13-25 33-9 1-55 13.26 33-9 1.546 13-22 ta 162 Aug. 26 22 4-2 2.048 14-57 u 184 Oct. 22 22 4- 2.059 14.65 10.9 1.986 14-36 50.0 1.115 12.31 19.1 1.878 14.11 50.0 1.128 12.46 34-2 i-55 12.91 60.3 0.823 11.79 49-4 1.144 12.48 60.3 0.827 11.85 65.0 0.693 11.67 65-5 0.668 11.46 65-5 0.663 "37 o> 163 Aug. 26 22 4-2 2.040 14-52 w 185 Oct. 22 22 4.0 2.060 14.66 10.9 2.002 14.46 50.0 1.103 12.18 19.1 1.886 14.18 50.0 1.105 12.21 34.2 1.548 13.29 65-5 0.652 11.17 49-4 1.149 12.54 65-5 0.647 II.08 65.0 0.688 "55 u 164 Aug. 26 22 4.2 2.029 14.44 w 186 Oct. 22 22 4.0 2.057 14.64 10.9 1-995 14.42 4-0 2.063 14.68 19.1 1.870 14.06 50.0 I.IOI 12.17 34-2 1.556 13-36 65.5 0.650 11.14 2O 49-4 1.152 12.56 65-5 0.628 iQ-75 20 65.0 0.700 11.76 MEAN RESULTS FOR EACH LATITUDE FROM ALL LINES. OBSERVATIONS OF 1908. TABLE 13. MEAN RESULTS FOR EACH LATITUDE FROM ALL LINES. OBSERVATIONS OF 1908. IOI PLATE No. + ! f PLATE No. v + v 1 PLATE No. s + r, PLATE No. + ! u 103 i5i io5i ios 2 i5 2 I05 2 i5 2 "3 "3i 7i U?2 128 134 I35i i35 2 136 146 147 148 151 IS' O.2 -3 -3 0.4 0.4 0.4 0.4 0.0 0.0 0.6 0.6 -5 0-5 o-S o-S o-S -3 -3 -3 -3 o-3 km 2.071 2.057 2.081 2.072 2.070 2.080 2.073 2.100 2.081 2.056 2.058 2.057 2.043 2.064 2.038 2.047 2.028 2.O52 2.056 2.062 2.o6o 14.71 14.60 H-77 14.72 14.71 14-77 14.72 14.92 14-77 14.60 14.61 14.61 14-51 14.66 14.46 14-53 14.40 14-57 14.60 14.64 14.63 <* 103 105! i05i i5 2 io5 2 106 "3 "3 "7i "7 2 I20 t 128 i3Si i35 2 146 H7 148 151 14.1 14.6 14.6 15-2 IS-2 15-2 14.9 14.9 14.4 14.4 17-3 14-5 14-5 14-5 iS-2 15-2 iS-2 14.6 km 1.948 1.989 1.971 956 .966 .971 .969 .961 .895 .898 .862 .917 .940 .938 934 959 959 952 14.26 J4-59 14.47 14-39 14-45 14-51 14.46 14.41 13.89 13-91 13-86 14.06 14.22 14.21 14-23 14.42 14.42 14-32 W I2O[ I2O] 132 134 136 161 162 163 164 165 166 182 183 183 183 32.8 34-8 34-4 34-5 34-5 34-2 34-2 34-2 34-2 34-1 34-1 33-9 33-9 33-9 33-9 km 645 .610 593 557 551 1-547 i-55 1.548 I-556 1-557 1.561 1.483 1-549 i-SSO 1.546 13.89 13-92 13-73 13-42 12.36 13-27 12.91 13-29 13-36 13-37 13-38 12.69 13-25 13.26 13-22 + , PLATES. + ! PLATES. + km km o km o km 4196.699 La 21 2.034 14.44 15 2.023 14.40 12 1.979 14-31 18 1.925 14.14 4197-257 CN 21 2.047 14-53 15 2.028 14 43 12 1.978 14-31 18 1.927 14.16 4203-730 Cr 21 2.061 14.63 IS 2-034 14.48 12 1.992 14.42 18 1-944 14.28 4207.566 CN 21 2.054 14.58 15 2.038 14 50 12 1.989 14-39 18 1-937 14-23 4216.136 CN 21 2.042 14.49 15 2.031 14.46 12 1.983 14-34 18 1.930 14.18 4220.509 Fc 21 2.059 14.62 15 2.052 14.61 12 1.998 14-45 18 1-945 14.29 4232.887 Fe 21 2.066 14.67 15 2.048 14 58 12 1.992 14-41 18 1.948 14.31 4233-328 Mn 21 2-055 14-59 15 2.052 14 61 12 1-995 14.43 18 1-945 14.29 4257-8I5 Mn 21 2.077 14-75 15 2.049 14 58 12 1.998 14-45 18 1-953 14.34 4258.477 Fe 21 2.068 14.68 15 2.046 14 56 12 1.998 14-45 18 1-952 14-34 4265.418 Fe 21 2.060 14.62 15 2.042 14-53 12 1-993 14.41 1 8 1.946 14.30 4266.081 Mn 21 2-073 14.72 15 2.051 14 60 12 1.997 14.44 1 8 1.946 14-30 4268.915 Fe 21 2.073 14.72 15 2-045 14 56 12 1-994 14.42 18 1-949 14.32 4276.836 -Zr 21 2.067 14.68 15 2.037 14.50 12 1.986 14.36 18 1.948 14-31 4283.169 Ca 21 2.066 14.67 15 2.039 I4-5I 12 1.991 14.40 18 1.948 14-31 4284.838 Ni 21 2.069 14.69 IS 2.040 14 52 12 1.988 14.38 18 1.936 14.22 4287.566 Ti 21 2.066 14.67 IS 2.036 14.49 12 1.988 14.38 18 1.944 14.28 4288.310 Ti, Fe 21 2.064 14.65 IS 2.036 14-49 12 1.990 14-39 18 1.949 14-32 4289.525 Ca 21 2.069 14.69 15 2.040 14.52 12 1.992 14.41 18 1.950 14-33 4290-377 Ti 21 2.059 14.62 15 2-034 14.48 12 1.986 14.36 18 1.938 14.24 4290.542 Fe 21 2.068 14.68 IS 2.040 14.52 12 1-994 14.42 18 1-953 14-35 4291.630 Fe 21 2.071 14.70 15 2.041 14-53 12 1.992 14.41 18 1-947 14-30 X ELEMENT. = I9t2 = 29^8 = 34?i = 44?8 4196.699 La 14 1.859 13.98 1 6 1.652 13 52 15 1.546 13.26 I? 1.275 12-75 4197-257 CN 14 1.859 13.98 16 I.655 13 54 15 1-544 13.24 I? 1.280 12.80 4203.730 Cr H 1.871 14.06 16 1.671 13 67 15 1.561 13.38 17 .288 12.88 4207.566 CN 14 1.875 14.10 16 1.667 13 64 15 1.560 13.37 17 -283 12.83 4216.136 CN 14 1.862 14.00 16 1.647 13-47 15 1.548 13.27 I? .272 12.72 4220.509 Fc 14 1.874 14.09 16 1.671 13 67 15 1.561 13-38 I? .288 12.88 4232-887 Fe 14 1.875 14.10 16 1.669 I3-65 15 1-559 13-37 17 .282 12.82 4233-328 Mn 14 1.878 14.12 16 1.662 13.60 15 1.561 13-38 I? .287 12.87 4257-8i5 Mn 14 1.876 14.10 16 .676 13 7i 15 1-567 13-43 I? .300 13.00 4258.477 Fe 14 1.871 14.06 16 -677 13 72 15 1.560 13-37 I? 294 12.94 4265.418 Fe H I.86I 13-99 16 .666 13-63 15 1-555 13-33 I? .284 12.84 4266.081 Mn 14 1-873 14.08 16 .672 13.68 15 1.561 13-38 I? .297 12.97 4268.915 Fe 14 I. 869 14.05 16 .673 13.69 15 1-559 13-37 I? .292 12.92 4276.836 -Zr H I. 864 14.02 16 .673 13-69 15 1-554 13-32 17 .284 12.84 4283.169 Ca 14 I. 866 14.03 16 .672 13.68 15 1-553 13.32 I? .287 12.87 4284.838 Ni 14 I. 860 13.98 16 .657 I3-56 IS 1-557 13-31 17 .282 12.82 4287.566 Ti 14 I. 862 14.00 16 .671 13-67 IS 1-554 13.32 i? .292 12.92 4288.310 Ti, Fe 14 I. 865 14.02 16 -675 I3-70 15 1.560 13.37 i? .291 12.91 4289.525 Ca 14 I. 861 13-99 16 .676 13-71 15 1-558 13-36 i? 297 12.97 4290.37? Ti 14 I. 858 13-97 16 .666 13 63 15 1-557 13-36 i? .278 12.78 4290.542 Fe 14 I. 869 14.05 16 683 13 77 IS 1-565 13-42 i? .294 12.94 4291-630 Fe 14 I. 871 14.06 16 .680 13 74 IS 1.562 13-39 i? 294 12.94 = 49^6 = 6O I = 65^0 = 75!o = 79^1 X ELEMENT. "Jo.OF > No. OF V No. OF No. OF No. OF , 1 'LATES. + ' PLATES +*, ? PLATES. + , * PLATES. + , ? km o km km km ' km 4196.699 La 16 125 12.32 22 0.791 11.26 17 0.658 11.05 17 0.380 10.42 7 0.267 IO.O2 4197-257 CN 16 .125 12.32 22 0.791 11.26 17 0.663 11.14 17 0.385 10.56 7 0.269 IO.IO 4203-730 Cr 16 .138 12.46 22 0.805 11.46 17 0.670 11.26 i? 0.392 10.75 7 0.269 IO.IO 4207.566 CN 16 .138 12.46 22 0.804 "45 17 0.666 11.19 17 0.388 10.65 7 0.270 10.14 4216.136 CN 16 .130 12.38 22 0.796 "34 !7 0.659 11.07 0.386 10.59 7 0.261 9.80 4220.509 Fe 16 .144 12.53 22 0.805 11.46 17 0.671 11.27 i? 0.400 10.97 7 0.267 IO.O2 4232-887 Fe 16 -138 12.46 22 0.801 11.41 0.671 11.27 17 0-397 10.89 7 0.266 9-99 4233-328 Mn 16 139 12.48 22 0.805 11.46 17 0.671 11.27 17 0.386 10.59 7 0.269 IO.IO 4257.815 Mn 15 .142 12.51 22 0.8 1 6 11.62 16 0.675 "34 17 0.406 11.14 7 0.281 ^0.55 4258.477 Fe 15 .138 12.46 22 0.807 11.49 16 0.672 11.29 17 0-399 10.94 7 0.267 10.02 4265.418 Fe 16 134 12.42 22 0.807 11.49 i? 0.672 11.29 17 0-397 10.89 7 0.277 10.40 4266.081 Mn 16 .141 12.50 22 0.805 11.46 17 0.676 11.36 17 0.402 11.03 7 0.282 10.59 4268.915 Fe 16 139 12.48 22 0.811 "55 17 0.482 11.46 17 0.404 11.08 7 0.277 10.40 4276.836 -Zr 16 .136 12.44 22 0.812 11.56 17 0.674 11.32 17 0.402 11.03 7 0.276 10.36 4283.169 Ca 16 139 12.48 22 0.811 "55 i? 0.672 11.29 17 0.398 10.91 7 0.274 10.29 4284.838 Ni 16 137 12.45 22 0.807 11.49 i? 0.673 11.31 0.406 11.14 7 0.270 10.14 4287-566 Ti 16 -134 12.42 22 0.810 "54 17 0.670 11.26 i? 0.400 10.97 7 0.274 10.29 4288.310 Ti, Fe 16 .140 12.49 22 0.810 "54 17 0.674 11.32 17 0-399 10.94 7 0.281 10.55 4289.525 Ca 16 .144 12.53 22 0.808 11.51 0.679 11.41 17 0-399 10.94 7 0.279 10.47 4290.377 Ti 16 132 12.40 22 0.800 "39 17 0.669 11.24 17 0.392 10.75 7 0.270 10.14 4290.542 Fe 16 .141 12.50 22 0.812 11.56 17 0.677 "37 17 0.402 11.03 7 0.270 10.14 4291.630 Fc 16 .144 12.53 22 0.813 ".58 17 0.676 11.36 17 0.400 10.97 7 0.278 10.44 ADAMS PLATE 2 OBSERVATIONS ON HYDROGEN. 103 9. SPECIAL OBSERVATIONS ON THE a LINE OF HYDROGEN. As will be seen when we reach the discussion of the results for the individual lines of the reversing layer on page lOQof this investigation, the observations of 1906-1907 and of 1908 agree in indicating that different lines give different velocities of rotation. Since this result clearly is connected with the level at which the lines originate in the sun's atmosphere, an investigation of the lines of the elements which show great dif- ferences of level becomes of much interest. The two elements which appear to rise to the greatest height above the solar photosphere, as indicated by observations of the chromospheric spectrum, are calcium and hydrogen. Unfortunately, accurate measures of the H and K lines of calcium at the sun's limb are very difficult, on account of the great variation in their width and appearance and the presence of bright reversals. Exclusive of these lines, the blue line of calcium at A. 4227, which represents a considerably lower level than H and K, remains. Among the hydrogen lines, H8 and Hf3 are practically ruled out on account of the presence of foreign lines, and Hy is rendered unsymmetrical by the same cause. Accordingly, in the selection of lines for measurement only Ha was left. The investigation of this line became of interest for several other reasons. Photographs of the spectra of the center and limb of the sun indicated that Ha was greatly widened at the limb, while the other hydrogen lines, with the possible exception of H@, were either unchanged or slightly narrowed. The line also showed no such displacement toward the red at the sun's limb as was found for essentially all of the lines in the solar spectrum. Moreover, plates taken with the spectroheliograph with the a line showed structure differing in many respects from that obtained through the other hydrogen lines. All of these results are in harmony with the chromospheric observations in indicating a very high level for the hydrogen gas which produces Ha in the sun's atmosphere. The measurement of the center and limb plates soon showed that the Ha line would give abnormally high rotational velocities, and the first photographs taken with the regular rotation apparatus confirmed this result. A few preliminary results of this investigation were published early in 1908 (15), but a much more extensive series of plates was obtained during the spring of that year. The use of fine-grained plates sensitized to the red by the use of Wallace's formula proved of the greatest value in the investigation, since the edges of the line are so hazy as to make the superior defining power of these plates, and their excellent contrast, of much assistance in the measurement. All of the results given were obtained from plates of this character. It is of course hardly necessary to state that the degree of accuracy attained in the measurement of Ha is of quite another order from that for the narrow lines of the reversing layer. The width of Ha at the sun's limb is about 1.15 Angstroms, as against 0.15 Angstrom for the lines employed in the reversing layer. Moreover, all of the plates used for measurement were taken in the spectrum of the second order, thus giv- ing a linear scale only two-thirds that used for the reversing layer. It seems probable that the accidental errors of setting must be several times as great for Ha as for the sharper and narrower lines. I have already referred to the marked widening and change in appearance of Ha at the sun's limb. The study of plates taken inside the limb soon showed that the greater part of this effect must take place within a comparatively narrow range, some 3 or 4 mm, on a solar radius of about 84 mm. This is what we should expect in case the change in the appearance of Ha is due to the great increase in the length in path of the light at the sun's edge, since the length of this path decreases very rapidly with increasing distance inward from the limb. Accordingly, two series of observations have been made, the first as close to the limb as the slit could be set without danger from the introduction of chromospheric light, and the second at an average distance of about 3 mm inside the limb. The details of these observations and the summaries of the results are given in Tables 15-18. The tables are similar in arrangement to those containing the data for the reversing layer. A comparison with the values for the normal places derived from the two series of observations on the reversing layer is given in Table 35. 104 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE 15. OBSERVATIONS ON THE a LINE OF HYDROGEN AT THE LIMB. PLATE No. GR. MEAN DATE. A 1! v + v l 8 PLATE No. GR. MEAN DATE.

"5 May 15 5 10 -0.4 0.192 2.01 2-15 iS-3 W I27i June 9 10 15 -0-5 0.195 2. 02 2-15 iS-3 14.6 0.184 1.89 2. 02 14.8 I4-S 0.184 1.90 2.03 14.9 29.6 o-iS3 i-59 I.7I 14.0 29-5 0.161 1.6? 1-79 14.6 44-9 0.122 1.28 i-39 13-9 44-S 0.122 1.27 1.38 13-7 6o. S 0.082 0.86 0.94 13-6 59-5 0.083 0.86 0.94 13-1 75-9 O.O42 0.44 0.48 14.0 75-o 0.045 0.47 0.52 14-3 w ii8[ June i 10 30 -0.6 0.194 2.02 2.15 iS-3 w 127-2 June 9 10 15 -0-5 0.197 2.04 2.17 iS-4 14.4 0.184 1.92 2.05 15.0 I4-S 0.182 1.89 2. 02 14.8 29.4 0.158 1.64 1.76 14-3 29-S 0.164 1.71 1.83 14.9 44-9 0.135 I.4I i-Si iS-i 44-S 0.125 1.30 I.4I 14.0 60.4 0.084 0.88 o-95 13-6 59-5 0.087 0.90 0.98 13-7 75-9 0.042 0-45 0-49 14-3 75-o 0.044 0.46 0.51 14.0 w ii8 2 June i 10 30 -0.6 0.196 2.04 2.17 15-4 w 129 June 10 2 40 -0.5 0.195 2.OI 2.14 15-2 14.4 0.184 1.92 2.05 'S-o 14-5 0.185 1.90 2.03 14.9 29.4 -I55 1.61 i-73 14.1 29-5 o.i 66 1.70 1.82 14.8 44-9 0.128 i-33 i-43 14-3 44-5 0.126 1.30 I.4I 14.0 60.4 0.086 0.89 0.96 13-8 S9-5 0.085 0.88 0.96 13-4 75-9 0.046 0.48 0.52 15-2 74-5 0.045 0.46 0.51 I3-S J 122 June 9 2 45 -o.S 0.192 2.00 2.13 iS-i <* I3l June 10 2 40 -0-5 0.196 2.02 2-IS iS-3 14-5 0.178 1.86 1.99 14.6 14-5 0.184 1.90 2.03 14.9 29-5 O.I 60 1.67 i-79 14.6 29-5 0.162 1.68 1. 80 14.7 44-5 O.I 2O 1.24 i-35 13-4 44-S 0.125 1.29 1.40 13-9 59-5 0.082 0.85 0-93 13-0 59-S 0.088 0.92 1. 00 14.0 7S- 0.042 0.44 0.49 13-4 74-5 0.046 0-47 0.52 13.8 <> 123 June 9 2 45 -0.5 0.196 2.03 2.16 iS-3 w I30 2 June 10 2 40 -0.5 0.196 2.02 2.15 15-3 14-5 0.182 1.89 2.02 14.8 I4-S 0.184 1.90 2.03 14.9 29-5 0.159 1.65 i-77 14.4 29-S 0.161 1.66 1.78 I4-S 44-5 0.126 i-3i 1.42 14.1 44-S 0.125 1.29 1.40 13-9 59-5 0.084 0.88 0.96 13-4 59-5 0.083 0.86 o-94 13-1 75- 0.041 0-43 0.48 13.2 74-5 0.048 0-49 o-54 H-3 W 124! June 9 2 45 -0.5 0.192 1.96 2.09 14.8 w 1311 June 10 2 40 -0-5 0.194 2.OO 2.13 iS-i I4-S 0.185 1.90 2.03 14.9 I4-S 0.185 1.89 2. 02 14.8 29-S 0.161 1.65 1.77 14.4 29-5 0.163 1.67 1.79 14.6 44-5 0.126 1.29 i-3i 13-0 44-5 0.125 1.30 I.4I 14.0 59-5 0.087 0.91 o-99 13-8 59-5 0.087 0.89 0.97 13-6 7S-o 0.046 0-47 0.52 14-3 74-5 0.045 0.46 O.SI 13-5 138 Aug. 4 12 30 0.4 0.182 1-95 2.08 14.8 14.9 0.176 1.90 2.03 14.9 14.3 0.174 1.87 2.00 14.7 29.9 0.151 1.63 i-75 14-3 30.2 0.150 1.61 1.72 14.1 45-i O.I 2O 1.30 1.41 14.2 45-4 0.116 1.26 1.36 13.8 60.8 0.078 0.84 0.92 13-4 60.6 0.070 0.80 0.8? 12.6 76.2 0.038 0.42 0.47 14.0 75-7 0.038 0.41 0-45 12.9 W I IQ! June i o 40 -0.6 0.184 1-99 2.12 iS-i w 142 Aug. 5 4 30 -o-3 0.187 2.OO 2.13 15.1 14.4 o.i7S 1.89 2. 02 14.8 14.6 0.177 1.90 | 2.03 14.9 29.4 0.148 1. 60 1.72 14.0 29-S 0.151 1-63 i-75 14.3 44-9 0.119 1.28 I. 3 8 13.8 44-7 O.I2I 1.30 I.4O 14.0 60.4 0.076 0.82 0.89 12.8 59-9 0.080 0.87 0-94 13.3 75-9 0.037 0.40 0.44 12.8 74-9 0.038 0.44 0.48 13.1 W IIQ 2 June i o 40 -0.6 0.184 1.99 2.12 15-1 w 143 Aug. 543 -0-3 0.186 1.99 2.12 15-0 14-4 0.172 1.86 1.99 14.6 14.6 0.174 1.86 1.99 14.6 29.4 0.148 i. 60 1.72 14.0 29-S 0.148 1-59 1.72 14.0 44.9 0.119 1.28 I. 3 8 13.8 44-7 O.IlS 1.23 i-33 13-3 60.4 0.074 0.80 0.87 12-5 59-9 O.oSo 0.86 0-93 13.2 75-9 0.036 0-39 0-43 12.5 74-9 0.040 0.47 0-51 13-9 w 137 Aug. 4 12 30 0.4 0.184 1.97 2.IO 14.9 (Jl 172 Aug. 27 ii 30 0-3 0.179 1-93 2.06 14.6 14-3 0.174 1.86 1.99 14.6 iS-2 0-173 1.85 1.98 14.6 30.2 0.145 1.61 1.72 14.1 30.0 0.146 i-59 1.71 14.0 45-4 O.I 2O 1.29 i-39 14.0 45- 0.116 1.27 i-37 13-8 60.6 0.073 0.80 0.87 12.6 60.2 0.077 0.86 o-93 13-3 75-7 0.038 0.41 0-45 12.9 7S-o 0.040 0.49 0.52 14-3 TABLE 18. OBSERVATIONS ON THE o LINE OF HYDROGEN WITHIN THE LIMB. RESULTS FOR EACH LATITUDE. , + ,, + , V + tl, km km km O.I 2.17 iS-4 14.9 2.03 14.9 29-9 i-75 14-3 0.6 2.12 i5-i 14.4 2.O2 14.8 29.4 1.72 14.0 0.6 2.12 15-1 14.4 1.99 14.6 29.4 1.72 14.0 0.4 2.10 14.9 14-3 1.99 14.6 30.2 1.72 14.1 0.4 2.08 14.8 14-3 2.OO 14-7 30.2 1.72 14.1 0.3 2.13 iS-i 14.6 2.03 14.9 29-5 '75 14-3 0-3 2.12 iS-o 14.6 1.99 14.6 29-5 1.72 14.0 -3 2 06 14.6 15-2 1.98 14.6 30.0 1.71 14.0 Means, 0.4 2. 112 15.00 14.6 2.OO4 14.71 29.8 1.726 14.10 V + t] . + *, , + ,, 9 45-i km 1.41 14.2 60.8 km 0.92 13-4 76.2 km 0.47 14.0 44-9 1.38 13-8 60.4 0.89 12.8 75-9 0.44 12.8 44-9 1.38 13-8 60.4 0.87 12.5 75-9 0-43 12.5 45-4 1-39 14.0 60.6 0.87 12.6 75-7 0.45 12.9 45-4 1.36 13-8 60.6 0.87 12.6 7S-7 0-45 12.9 44-9 1.40 14.0 S9-9 0.94 13-3 74-9 0.48 13-1 44-7 i-33 13-3 59-9 0-93 13.2 74-9 0.51 13-9 45-o i-37 13-8 60.2 0-93 13-3 75-o 0.52 14-3 Means, 45.0 1-378 13.84 60.4 0.902 12.96 75-5 0.469 13-30 OBSERVATIONS ON CALCIUM. 107 10. SPECIAL OBSERVATIONS ON X 4227 OF CALCIUM. The line X 4227 of calcium appears upon all of the plates taken for the investigation of the rotation of the sun with the lines of the reversing layer. The quality of these negatives, however, is not well adapted for the study of this line, which is very diffuse and has broad wings extending on either side. Accordingly, I have taken a separate series of plates in which the density is made sufficiently great to reduce these wings considerably and thus define the central portion of the line to somewhat better advantage. In spite of this fact its measurement is difficult, and it is doubtful whether the degree of accuracy attained is any higher than in the case of Ha. In Tables 19 and 20 are found the details of the observations and a summary of the results. The values for the normal places are collected and compared with those for the reversing layer in Table 36. TABLE 19. OBSERVATIONS ON \ 4227 or CALCIUM. PLATE No. GR. MEAN DATE. A 11 D + Uj PLATE -No. GR. MEAN DATE. A i} ZJ + tlj 1 igo8 h m km km 1908 h m o km km a 149 Aug. 5 ii 40 0.4 0.182 1-97 2.10 14.9 i 167 Aug. 27 7 o 0.6 0.184 2.01 2.15 15.3 IS-S 0.172 1.87 2.OO 14.7 15.0 0.176 1.92 2.05 15.1 30.2 0.150 1.63 J-75 14.4 29.8 0.152 1.67 1.79 14.6 45-6 O.I 1 1 1. 21 i-3i 13-3 44-8 0.119 1.30 1.40 14.0 60.8 0.070 0.77 0.84 12.2 60.0 0.074 0.85 0.92 13.1 75-5 0.036 0.44 0.48 13.6 74.8 0.038 0.42 0.46 12.5 u 150 Aug. s ii 40 0.4 0.180 i-95 2.08 14.8 u 168 Aug. 27 7 o 0.6 0.182 1.98 2.12 15.0 15-3 0.172 1.86 1.99 14.6 15.0 0.176 1.91 2.04 15.0 30.2 0.147 i. 60 1.72 I4.I 29.8 0.150 1.64 I. 7 6 14.4 45-6 O.I 1 1 1. 21 i-3i 13-3 44.8 0.119 1.30 1.40 14.0 60.8 0.068 0-75 0.82 II.9 60.0 0.077 0.85 0.92 13.1 75-5 0-035 O.42 0.46 13-0 74-8 0.044 0-54 0.58 15.7 01 152 Aug. 6 5 40 0-3 0.185 2.01 2.14 15.2 u 169 Aug. 27 70 0.6 0.184 2.01 2-15 15.3 iS-2 0.171 1.85 1.98 14.6 15-0 0.176 1.92 2.03 14.9 3o.i 0.148 1.62 1-74 14-3 29.8 0.152 1.62 1.74 14.2 45-2 O.II2 1.22 1.32 '3-3 44-8 0.118 1.29 i-39 13.9 60.4 O.O72 0.79 0.86 12.4 60.0 0.074 0.82 0.89 12.6 75-4 0.034 0.41 0-45 12.7 74-8 0.043 o-S3 o.S7 15.4 w 153 , Aug. 6 5 40 -3 0.183 i-99 , 2.12 IS-I w 170 Aug. 27 70 0.6 o.i 86 2. 02 2.16 15.3 15.2 O.I7I 1.86 1.99 14.6 15-0 0.176 1.92 2.05 15.1 30.1 0.148 1.64 1.76 144 29.8 0.149 1.6 3 1-75 14-3 45-2 O.II2 1.22 1.32 13-3 44-8 0.120 1.32 1.42 14.2 60.4 0.070 0.77 0.84 12. 1 60.0 O.o8o 0.89 0.96 13.6 75-4 0.033 o-39 0-43 12. 1 74.8 O.O42 0.51 0-55 14.9 w 154 Aug. 6 5 40 -3 O.lSo 1.97 2.10 14.9 188 Oct. 22 10 30 O.I 0.184 1.99 2-13 15.1 15-2 0.174 1.89 2.O2 14.9 14.8 O.I72 1.86 2.00 14.7 30.1 0.148 1.64 1.76 14.4 29.8 0.153 1.66 1.79 14.6 45-2 O.II4 1.23 i-33 13-4 44.9 O.II5 1-25 1.36 13.6 60.4 0.067 0.74 0.81 II.6 60.2 0.075 0.79 0.87 12.4 75-4 0.032 0.38 0.42 n.8 75-9 0.039 0-45 0-49 14.3 O.I O.lSl 1.96 2.IO 14.9 <" iS7 Aug. 13 s 10 -o-3 0.184 1.99 2-13 15-1 w 189 Oct. 22 IO 30 14.8 0.175 1.88 2.02 14.8 14.6 0.176 1.91 2.04 15.0 29.8 0.154 1.67 1. 80 14.7 2Q-S 0.147 i-59 1.71 13-9 44-9 0.118 1.28 1-39 13.9 44.1 0.116 1.26 1.36 13-4 60.2 0.079 0.85 0-93 13-3 S8-4 0.073 0.81 0.89 I2.O 75-9 0.037 0.44 0.48 14.0 72.0 0.037 0.42 0.47 10.8 w 158 Aug. 13 5 10 -o-3 0.182 1.97 2. II 15.0 14.6 0.176 1.91 2.04 15-0 29-5 0.146 1.58 1.70 13-9 44.1 0.114 1-23 i-33 13-1 58-4 0.074 0.8 1 0.89 I2.O 72.0 0.041 0.48 o-53 12.2 I08 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE 20. OBSERVATIONS ON x 4227 OF CALCIUM. RESULTS FOR EACH LATITUDE. JJ + Uj tl + Bj { + , km . km kra 0.4 2.10 14-9 15-3 2.OO 14.7 30.2 75 14.4 0.4 2.08 14.8 15-3 1. 99 14.6 30.2 .72 14.1 0-3 2.14 15-2 15-2 1.98 14.6 30.1 74 14-3 -3 2.12 15-1 15-2 1-99 14.6 30.1 .76 14.4 -3 2.10 14-9 15-2 2. 02 14.9 30.1 .76 14.4 -3 2-13 15-1 14.6 2.O4 15.0 29-5 71 13-9 -3 2. II 15-0 14.6 2.04 15.0 29-5 .70 13-9 o.ft 2-IS iS-3 15.0 2.0S 15-1 29.8 79 14.6 0.6 2.12 15.0 15.0 2.04 15.0 29.8 .76 14.4 0.6 2-15 iS-3 15-0 2-03 14.9 29.8 74 14.2 0.6 2.16 iS-3 15.0 2.05 15-1 29.8 75 14-3 O.I 2.13 iS-i 14.8 2.OO H-7 29.8 79 14.6 O.I 2.IO 14.9 14.8 2.02 14.8 29.8 .80 14.7 Means, 0.38 2.122 15-07 15.00 2.OIQ 14-85 29.88 1-752 14.32 + , J + r, + fj J . km km km 45-6 I-3I 13-3 60.8 0.84 12.2 75-5 0.48 ! 3 .6 45-6 l-3> 13-3 60.8 0.82 II.9 75-5 0.46 13.0 45-2 1.32 13-3 60.4 0.86 12.4 75-4 o-4S 12.7 45-2 32 13-3 60.4 0.84 12. 1 75-4 o.43 12. 1 45-2 33 13-4 60.4 0.81 n.6 75-4 0.42 n.8 44.1 36 13-4 58.4 0.89 12.0 72.0 0.47 10.8 44.1 33 13-1 58-4 0.89 12.0 72.0 o-53 12.2 44.8 .40 14.0 60.0 0.92 I3-I 74.8 0.46 12-5 44.8 .40 14.0 60.0 0.92 I3-I 74-8 0.58 15-7 44.8 39 13-9 60.0 0.89 12.6 74-8 o-57 iS-4 44.8 42 14.2 60.0 0.96 13.6 74-8 0-55 14.9 44-9 36 13-6 60.2 0.87 12.4 75-9 o-49 14-3 44-9 39 13-9 60.2 0-93 13-3 75-9 0.48 14.0 Means, 44.92 1-357 13-52 60.00 0.880 12.48 74.78 0.490 I3-3I DISCUSSION OF THE RESULTS. ii. SYSTEMATIC DEVIATIONS OF VELOCITY or ROTATION DERIVED FROM VARIOUS LINES OF THE REVERSING LAYER. ONE of the most important questions connected with the results of this investigation is whether the lines of different elements give values which differ from one another in any systematic way, indicating a longer or shorter period of rotation for the various elements in the sun's atmosphere. The behavior of the individual lines in this regard will be shown best if we form the difference in the value of the angular velocity of for each line from that of the mean of all the lines. Any systematic effect will show itself at once by the marked preponderance of the positive or the negative sign in the residuals. The results of such a comparison are given for the two series of observations in Tables 21 and 22. In forming these differ- ences I have rounded off the results to one place of decimals, although the reduction tables have been carried to two places. This has seemed desirable in order to facilitate rapid comparison of the results. In the formation of the mean deviations for several latitudes, however, the second place has been retained. An examination of these tables leads to several important conclusions. The most striking of these are, on the one hand, the systematically low values given by the lanthanum line at X 4196.699, the cyanogen lines A. 4197.257 and X 4216.136, and the enhanced line of titanium at X 4290.377 ; and, on the other hand, the high values given by X 4257.815 and possibly one or two other lines in the list. The evidence for con- cluding that lanthanum and cyanogen occupy a relatively low level in the sun's atmosphere has already been referred to in connection with the discussion of the selection of the lines chosen for measurement. In the case of lanthanum reference should be made to an additional point of evidence, namely, that its lines, like those of other elements of very high atonu'c weight, are much weakened at the sun's limb. The fact, accordingly, that the lines of cyanogen and lanthanum give consistently low values for the angular velocity of rotation indicates that the sun's period of rotation increases as we approach its surface, or that the outer layers of the solar atmosphere move more rapidly than those lying close to the photosphere. This is in agreement with the results found for hydrogen and other substances which rise to a great height above the solar surface, and to which extended reference will be made later. TABLE 21. DEVIATIONS OF ANGULAR VELOCITY FOR INDIVIDUAL LINES FROM MEAN VALUE. OBSERVATIONS OF 1906-1907. \ ELEMENT. O2 ?!? I5?o 22?7 29! 8 37?8 44?6 S2?7 S96 6s?6 75?i 8o?4 4196.699 La O.O O.O O.I o. O.I 0.2 0.2 -0-3 -0.4 -0-3 -0.8 -o-3 4197-257 CN 0.0 0.0 O.O 0. O.O O.2 O.I -0-3 0.2 -o-3 -0.8 -0.4 4203.730 Cr + 0.2 +0.1 +0.1 0.0 +0.1 O.O 0.0 0.0 +0.1 O.O +0.2 +0.2 4209.144 Zr +0.2 +0.1 +0.1 +0. +0.2 +0.1 +0.2 O.O +0.2 +0.1 +0.1 +0.1 4216.136 CN O.I 0.0 O.I 0. O.2 O.I O.2 -0.3 0.2 -0-4 -0.8 -o-3 4220.509 Fe +0.1 +0.1 +0.1 +0. +0.2 +0.1 +0.1 0.0 O.O 0.0 +0.2 +0.4 4232.887 Fe +0.1 +0.1 +0.1 +0. +0.1 0.0 0.0 O.O +0.1 +0.1 +0.1 +0.1 4257-813 Mn +0.1 +0.2 +0.1 +0.2 +0.2 +0.2 +0.2 +0.2 +0.2 +0.3 +0.6 +0.3 4258.477 Fe 0.0 O.O O.O 0.0 O.O 0.0 0.0 0.0 +0.2 +0.1 +0.2 -0.4 4265.418 Fe 0.0 O.O +0.1 O.O 0.0 0.0 0.0 O.O +0.1 0.0 0.0 O.O 4266.081 Mn O.O + 0.1 0.0 +0.1 +0.1 +0.1 +0.1 +0.2 +0.2 +0.2 +0.5 +0.4 4268.915 Fe 0.0 O.O O.O 0.0 O.O O.O 0.0 0.0 O.O +0.2 +0.1 0.0 4276.826 -Zr 0.0 +0.1 0.0 O.O 0.0 0.0 0.0 0.0 0.0 +0.1 0.0 O.O 4284.838 Ni O.O O.I O.O O.O o. O.O O.O +0.1 0.0 0.0 O.O 0.0 4287.566 Ti 0.0 O.I O.O 0.0 o. O.O 0.0 0.0 +0.1 +0.1 +0.1 +0.1 4288.310 Ti, Fe 0.0 O.I O.I O.O O.O 0.0 O.I +0.1 0.0 0.0 +0.1 O.O 4290.377 Ti -0.2 0.2 O.I O.I 0. O.I O.I +0.1 O.I O.O O.I -0.4 4290.542 Fe O.I O.I O.I 0.0 o. 0.0 O.I 0.0 O.I 0.0 +0.1 O.I 4291.630 Fe O.I O.I O.I O.I 0. 0.0 O.O 0.0 O.I +0.1 +0.4 O.O 4294.936 Zr O.I O.I O.I O.I 0. O.O O.O +0.1 +0.1 0.0 O.O 0.0 109 110 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE 22. DEVIATIONS OF ANGULAR VELOCITY FOR INDIVIDUAL LINES FROM MEAN VALUE. OBSERVATIONS OF 1908. X ELEMENT. o?4 4! I ll2 I4?9 JQ2 2g8 34? I 44? 49?6 60! I 65? 7S?o 79? I 4196.699 La 0.2 O.I O.I O.I O.I O.I o O.I O.I o O.I O.2 O.2 -0.4 0.2 4197-257 CN O.I O.I O.I -O.I O.I O.I O.I O.I -O.I 0.2 0.2 -0.3 O.I 4203.730 Cr o.o o.o o.o o.o o.o o.o o.o o.o o.o 0.0 0.0 O.I O.I 4207.566 CN o.o o.o 0.0 o.o + 0.1 o.o o.o o.o o.o o.o O.I -0.5 O.I 4216.136 CN O.I O.I O.I O.I o.o -0.2 O.I 0.2 O.I O.I O.2 -0.3 -0.4 4220.509 Fe 0.0 0.0 o.o 0.0 0.0 0.0 +0.1 0.0 +0.! o.o 0.0 +0.1 0.2 4232.887 Fe o.o o.o o.o o.o +0.1 o.o o.o O.I 0.0 O.I 0.0 o.o -0.3 4233-328 Mn o.o +0.1 o.o o.o +0.1 o.o o.o o.o 0.0 0.0 o.o -o-3 -0.2 4257.815 Mn +0.1 0.0 0.0 + 0.1 +0.1 +0.1 + 0.1 +0.1 +0.1 + 0.1 + 0.1 +0.3 +0.3 4258.477 Fe 0.0 0.0 o.o +0.1 0.0 + 0.1 0.0 + 0.1 0.0 o.o o.c +0.1 +0.2 4265.418 Fe o.o o.o o.o o.o o.o o.o o.o o.o 0.0 0.0 0.0 0.0 + 0.2 4266.081 Mn +0.1 +0.1 0.0 o.o o.o +0.1 o.o +0.1 o.o o.o + 0.1 + 0.2 +0.3 4268.915 Fe + 0.1 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 + 0.! +0.2 +0.2 +0.2 4276.836 -Zr o.o 0.0 o.o o.o o.o 0.0 0.0 0.0 0.0 +0.1 0.0 + 0.2 + 0.1 4283.169 Co. o.o o.o o.o o.o o.o o.o o.o o.o o.o +0.1 o.o o.o o.o 4283.838 Ni o.o 0.0 0.0 O.I O.I O.I o.o O.I o.o o.o o.o +0.2 O.I 4287.566 Ti 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 O.I o.o +0.1 0.0 4288.310 Ti, Fe o.o o.o o.o o.o o.o o.o o.o o.o 0.0 + 0.1 o.o + 0.1 +0.3 4289.525 Ca o.o o.o o.o o.o o.o +0.1 o.o +0.1 + 0.1 o.o + 0.1 + 0.1 + 0.2 4290.377 Ti 0.0 0.0 0.0 0.0 O.I 0.0 0.0 O.I 0.0 O.I 0.0 O.I O.I 4290.542 Fe 0.0 0.0 0.0 +0.1 0.0 +0.1 +0.1 +0.1 0.0 + 0.1 +0.1 +0.2 O.I 4291.630 Fe +0.1 o.o o.o o.o o.o +0.1 o.o +0.1 +0.1 +0.1 +0.1 +0.1 + 0.2 The agreement of the two series of observations as regards the amount of this effect in the lower lati- tudes is excellent. The 1906-1907 observations give o.io for the lanthanum line between o and 45 of Latitude, and the 1908 observations give on. Similarly for the mean of the cyanogen lines the earlier observations give 0.09 and the later observations o.u. A difference of o.io in the value of the angular velocity at the equator would correspond to a difference in the rotation period of about 0.17 day. The enhanced line of titanium at X 4290.377 is of especial interest. It is well known from observations of the spectrum of the chromosphere that the enhanced lines, as a class, are relatively much more promi- nent in the chromosphere than they are in the ordinary solar spectrum. This would apparently indicate a higher average level in the sun's atmosphere. On the other hand, the line is considerably shifted at the limb of the sun,* and this points to a relatively low level. The systematically low value of the angular velocity of rotation furnishes additional evidence in the same direction. Further evidence is afforded on this subject by the only other enhanced line in either list, that due to iron, X 4233.328. The mean value of I in its case agrees closely with the mean derived from all the lines. Since it is a very prominent chromo- spheric line, however, the fact that it does not give a large value for the angular rate of rotation is strong evidence that it does not originate at any very considerable height in the sun's atmosphere. The explana- tion of this apparent discrepancy of results is not at present clear. It seems fairly probable that the diffi- culty will be found to be due to the interpretation of the chromospheric results, and that the relative strength of the enhanced lines does not necessarily indicate a higher level in the solar atmosphere. One hypothesis founded on this basis was published by Evershed in 1900 (18). Another possible explanation is indicated by some preliminary results obtained by Mr. Gale and myself while working on the displacements in the spectrum of a spark under pressure, but considerable additional material will be necessary to give it adequate weight. Of the lines which give positive residuals, that due to manganese at X 4257.815 is the most prominent in both series of observations. This line is not a chromospheric line, at least of any considerable intensity, nor is it much affected at the sun's limb. In sun-spots it is slightly strengthened. There is some evidence in both sets of observations, especially in the earlier, that X 4266.081 gives similar results. It is included * In referring to shifts at the sun's limb, the differential shift compared with the center of the sun as freed from rotational displace- ments is always understood. For convenience we may designate it as "pressure" shift, although pressure alone is probably not suffi- cient to account for all the effects observed. DEVIATIONS IN HIGHER LATITUDES. Ill as a chromospheric line in some lists, but is of comparatively slight intensity. The three lines in the list which are most strengthened at the sun's limb, X 4232.887, X 4258.477, and A. 4291.630, all give values close to the mean, with a very slight tendency toward positive residuals. Reference should also be made to the line at X 4207.566. This is assigned in Rowland's table to iron, but in the list of corrections is transferred to carbon. Its appearance is strongly indicative of a compound origin, as it is much wider than other lines of the same intensity in its vicinity. At the limb of the sun it shows a considerable displacement so much larger, in fact, than other neighboring cyanogen lines as to make its composite character almost certain. Accordingly, the evidence afforded by this line can not be considered as contradictory to that of the other cyanogen lines in the list. 12. INCREASE OF DEVIATIONS IN HIGHER LATITUDES. Another possible conclusion of great importance is afforded by an inspection of these tables, but it should be accepted with considerable caution. This is the apparent increase in the amount of the devia- tions for such lines as show systematically large or small values of the angular velocity toward the sun's pole. Thus the average deviation from the mean for the two cyanogen lines X 4197.257 and X 4216.136 between latitudes 60 and 80 is o3 as against o?i between latitudes o and 20. Similarly the lan- thanum line X 4196.699 gives o?3 against o?i, while the manganese line X 4257.815 gives +o?3 against +o?i. The 1908 observations give considerably smaller values for these differences than do the earlier results, but the effect is still well marked, the values in the higher latitudes amounting to more than twice those near the equator. It is of course true that a very small difference in linear velocity in the higher latitudes corresponds to a large difference in angular velocity, and so a wider range is to be expected among the values for the individual lines. For example, at the equator a change in the linear velocity of o.oi km corresponds to 0.07 in the angular velocity, while at 80 of latitude it corresponds to 0.41. If due to this cause, however, we should expect the values of the differences in the higher latitudes to be both larger and smaller than those near the equator and not to exhibit this systematic increase. In spite of this effect, the evidence might be considered rather doubtful if it were not for the strong support afforded by the behavior of two lines of elements which rise to a great height in the sun's atmosphere. These are the a line of hydrogen and X 4227 of calcium. The results for these lines will be considered in detail at a later point in this discussion, though the evidence furnished by them regarding changes of rotation rate in the higher latitudes properly belongs here. In the brief accompanying table are given the differences for such lines as show systematically large or small values of the angular velocity from a mean obtained from all the lines in the reversing-layer list. X ELEMENT. LATITUDE - 20 LATITUDE 60 - 80 4196.699 La O.I -0.3 4197-257 \ 4216.136] CN O.I -o-3 4257-815 Mn + 0.1 + 0.3 4226.904 Ca + 0.4 + 1.6 6563.045 II + 0.6 + 2.8 The great increase in the value of in the case of the last two lines is most striking, and in spite of the relatively low degree of accuracy attained in the measurement of these lines as compared with those of the reversing layer, such differences as these must certainly be considered as real. Accordingly, we may say that there is a strong presumption for concluding that, in the case of lines showing relatively large or small velocities at the equator, the values of deviations from the mean increase in the higher latitudes. It is of interest to note that the variations in angular velocity which Halm believed he had discovered during the different years included in his observations were greatest toward the pole. 112 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. 13. MEAN RESULTS FOR THE REVERSING LAYER VARIABILITY OF THE SOLAR ROTATION - COMPARISON OF RESULTS WITH THOSE OF OTHER OBSERVERS. We may now pass on to an investigation of the general results. While it appears clear from the pre- ceding considerations that certain lines in the list give values which are systematically high or low, the number of lines of the two kinds seems to be so nearly equal that no appreciable error from this source will affect the mean taken from all the lines. If we form means of the results of the two series of observations for the normal points of latitude indicated in Tables 6 and 13, we obtain the values given in Table 23. The weights are according to the number of observations. The results are shown graphically in Fig. i , the dotted curve corresponding to the 1906-1907 observations and the full-line curve to the 1908 observa- tions. In each case the agreement of the points with the curve is excellent, the largest deviation falling at the points of lowest weight. Km "^ -V V -N , \ \ s x^ ^V X > V ^V N V N, N X v X % x v+v. \ 0" I 0' 2 0* O' 4 0* if 6 n 6 t D' 8 3- act FIG. i. Curves representing the variation of radial velocity with heliographic latitude for the two series of observations 1906-1907 and 1908. The broken-line curve represents the 1906-1907 observations, the full-line curve those of 1908. RESULTS FOR THE REVERSING LAYER. TABLE 23. MEAN RESULTS FOR THE REVERSING LAYER. OBSERVATIONS OF 1906-1907. OBSERVATIONS OF 1908. WEIGHT. tl + Hj PERIOD. WEIGHT. + , 1 PERIOD. km days km days O.2 21 2.074 14-73 24-44 0.4 21 2.062 14.64 24.59 7-7 IS 2.028 14.53 24.77 4.1 IS 2.040 14-53 24.78 iS-O 24 1-957 14.40 25.00 II. 2 12 .991 14.40 25.00 22.7 1.3 1.811 13-94 25.82 14.9 18 944 14.28 25.21 29.8 24 1.676 13-71 26.26 19.2 14 .867 14.04 25.64 37-8 16 1.461 13-13 27-42 29.8 16 .669 13.65 26.37 44.6 23 1.283 1 2.80 28.12 34-i IS 557 J 3-35 26.96 52-7 18 i. 060 12-43 28.96 44-8 17 .287 12.87 27.97 59-6 24 0.867 12.15 29.63 49.6 16 137 12.45 28.92 65.6 20 0.604 11.96 30.10 60. i 22 0.806 11.49 31-33 75-i 33 0-435 11.98 30-OS 65.0 17 0.671 11.30 31-86 80.4 ii 0.277 11.80 30.51 75-o 17 0.396 10.86 33-15 79.1 7 0.272 10.25 35-12 The most interesting question involved in these results is whether an actual variation in the sun's rate of rotation is indicated. To facilitate direct comparison the values from the two series of observations for every 5 of latitude are given in Table 24. They are obtained from empirical formulas which satisfy the observations closely. The derivation of these formulae will be indicated later in the discussion. TABLE 24. COMPARISON OF THE RESULTS FOR THE Two SERIES. v + v l 1 1906-1907 1908 DIFFERENCE. 1906-1907 1908 DIFFERENCE. km 2.064 km 2-053 km + O.OII 14.63 14.61 + O.O2 5 2.052 2.041 + 0.01 1 14.60 14-58 + 0.02 10 2.015 2.OO6 + 0.009 14.51 14.49 + 0.02 15 1.956 1.947 + 0.009 14.37 14.34 + 0.03 20 1.877 .869 + 0.008 14.18 14.14 + 0.04 25 1.779 .772 + 0.007 13-94 13.89 + 0.05 30 1.666 .660 + 0.006 13.68 13.60 + 0.08 35 1-542 534 + 0.008 13-39 13.28 + O.II 40 1.409 399 + O.OIO 13.10 12.94 + 0.16 45 1.272 258 + 0.014 12.81 I2 -59 + 0.22 So 1.132 .114 + 0.018 12.54 12.24 + 0.30 55 0.992 0.968 + 0.024 12.30 11.90 + 0.40 60 0.852 0.822 + 0.030 12. II 11.58 + 0-53 65 0-713 0.678 + 0.035 11.97 11.29 + 0.68 70 0.576 0-537 + 0.039 II.9O 11.04 + 0.86 75 0-437 0.400 + 0.037 11.91 10.84 + 1.07 An inspection of these results shows that the 1908 observations give slightly smaller values than the earlier series between latitudes o and 40, and decidedly smaller values between 45 and 80. In the lower latitudes the largest difference is at the equator and amounts to o.oi i km for v + v v Although this is per- haps larger than might be expected from the internal agreement of the measures, it is hardly sufficient to warrant the conclusion that a source of systematic error is present, or that any variation in the sun's rate of rotation is indicated. In the higher latitudes the case is somewhat different, however. At latitude 70 a maximum difference of 0.039 km is reached, a quantity which is decidedly larger than would be expected from errors of measure- 114 AN INVESTIGATION OP THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. ment alone, even though it has been found that such errors are usually greater in high latitudes. At pres- ent! it does not seem possible to decide whether this lack of agreement is due to a real variation in the sun's rate of rotation, to the presence of some source of systematic error in the observations, or to the disturbing effect of proper motions in the sun's reversing layer. I am inclined, however, to ascribe it mainly to small systematic errors in the earlier series of observations. The principal sources of error to which these were subject have already been referred to, and there is little doubt that they must have affected the results to some extent. As several of these difficulties were eliminated, or their effect much reduced, in the later series of observations, and as the check by means of the exposure on the sun's pole was available in the later results, it is highly probable that the greater part of the difficulty is to be looked for in the earlier series. If such is the case, the single most serious cause of error is probably the astigmatism of the sun's image. The influence of proper motion in the reversing layer may be very appreciable in its effect upon the values of the solar rotation, and it is possible that this cause may be in part accountable for the discrepan- cies between the two series of results. As will be shown in another place, proper motions amounting to as much as 0.2 km have been found in a disturbed region in the neighborhood of spots, and of course it is highly probable that motions of smaller amount are present frequently. The probability of their occur- rence in high latitudes, however, would appear to be less than in the zones of chief spot activity. There seem to be three main arguments against the conclusion that these results indicate an actual variation in the sun's period of rotation. The first of these is that the variation, if present, seems to be confined to the higher latitudes. It would certainly appear probable that such an effect would be marked in the zones of greatest spot activity, between 10 and 30 of latitude, and differences in these zones were found by Halm (9) in the series of observations from which he concluded the existence of such a variation. On the other hand, the values given here indicate essentially no difference for the years 1906-1907 and 1908 between o and 40 of latitude. We have seen, however, that all of the spectrum lines which show abnormal values of the rotational velocity, such as those of cyanogen, lanthanum, calcium, and hydrogen, appear to give the largest deviations from the normal values in the higher latitudes. Accordingly, the existence of a variation in the sun's rate of rotation which is confined to high latitudes is perhaps less anomalous than might at first appear. A second argument against the occurrence of a variation in the sun's rotation period is the close agree- ment of the results given here for 1908 with Duner's values obtained from observations extending through six years, from 1887 to 1889 and from 1899 to 1901. A comparison of the 1906-1907 and 1908 observa- tions with those of Duner for the six latitudes employed by him gives the results in Table 25, the values being obtained in all cases from the corresponding empirical formulas. TABLE 25. COMPARISON OF THE RESULTS WITH THOSE or DUNER. 1906-1907 1908 DUNER. , + ,, , + ,, ,+., * km 2.06 14.62 km 2.05 14-54 km 2.08 14.81 IS 1.96 14.38 i-95 14-32 1.97 14-53 3 1.6 7 13.66 1.66 13.61 1.6 7 13.76 45 1.27 12.77 1.26 12.64 1.26 12.70 60 0.8 S 12. IO 0.82 11.67 0.82 11.65 75 0.44 12. OO 0.40 10.96 0.40 10.88 The agreement of the 1908 observations with those of Duner is remarkably close on the average. This is especially true in the higher latitudes, the very region in which the probability of a variation in the rotation period is mainly in question. Accordingly, we may conclude that the evidence furnished by this comparison is decidedly against the existence of such a variation. COEFFICIENTS OF FAYE's FORMULA. In a discussion, however, advocating the existence of a variation in the sun's rate of rotation, Halm maintains that Duner's observations themselves furnish evidence of such a variation (9), with a period of about three years. In comparing the Edinburgh and Upsala results, Halm has made use of Faye's formula v + z>i = (a b sin 2 ) cos connecting the rotational velocity with the heliographic latitude. In this form, as will be shown later, the 1908 observations give v + v l = (2.053 ~~ o -546 sin 2 ) cos <#> Table 26 contains the values obtained by Halm for the coefficients a and b, with the Mount Wilson values added for comparison. TABLE 26. COEFFICIENTS OF THE FA YE FORMULA. OBSERVATIONS. DATE. a b Upsala .... 1899.5 1.98 0-57 1900-5 2. II O.4O 1901.5 2.O9 0.79 Edinburgh . . . 1901.7 1902.5 I903-S 2.O6 1-973 2.036 O.7O 0.560 0.251 1904-5 2.075 O.27I IQOS-S 1906.3 2.039 2.OIO 0-245 0.294 Mount Wilson . . 1907.0 1908.5 2-055 2-053 0.480 0.546 The Faye formula, as will appear later, does not fully satisfy the 1906-1907 observations, but the approximation is sufficiently close for the purposes of this comparison. On the basis of a three-year period, with a minimum near 1902.5, it is evident that 1908.5 should also give a minimum value of a. Actually, however, it is nearly equal to the largest value obtained by Halm between 1901 and 1906. Moreover, the value of a for 1907.0 is practically identical with that for 1908.5, and decidedly larger than Halm's value for the neighboring epoch 1906.3. Similarly, the Mount Wilson values of b are much larger than would be expected from comparison with the Edinburgh results, and are decidedly opposed to the idea of a periodic variation in this quantity. A third main objection to the conclusion that a real variation of the rotation period is indicated by the differences between the results obtained from the two series of observations is closely connected with the preceding. It is the fact that the 1908 observations are well represented by Faye's formula, while the 1906-1907 results show systematic discordances of such size as to necessitate the use of an additional constant in the equation. Since the results of Duner and the mean values obtained by Halm are well represented by this formula, and it has additional support in the observations of the rotation period of sun-spots, it seems improbable that the discordances given by the earlier series of observations can be other than inherent in the results themselves. This is indicated by the discussion that follows. A solution of the 1906-1907 results by least squares, weighting the observations according to their number, gives the following form of Faye's equation : v + Vi = (1.575 + 0.480 cos 2 <) cos This equation gives the residuals which appear in the third column of Table 27, the differences being observed computed. Il6 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE 27. REPRESENTATION OF THE 1906-1907 OBSERVATIONS BY EMPIRICAL FORMULAE. I II WEIGHT. *. + .,) A B 0.2 21 km + O.Oig km + O.OIO + O.IO 7-7 IS O.OOO 0.007 - 0.03 15.0 24 + 0.003 + O.OOI + 0.03 22.7 13 O.OlS 0.014 O.II 29.8 24 - 0.005 + 0.005 + O.O2 37-8 16 O.O2I 0.008 O.IO 44.6 23 O.OII O.OOO - 0.03 52.7 18 O.OOI + 0.004 + 0.02 59-6 24 + 0.009 + 0.005 + 0.03 65.6 20 + O.OIO O.OO2 o.oo 75-i 33 + O.O2I O.OOO + 0.07 80.4 ii + 0.014 0.008 0.21 The residuals under I are so clearly systematic in character as to necessitate the addition of a term in cos 2 (/>. A solution by least squares with the inclusion of such a term gives the equation v + v^ = (1.791 0.621 cos + 0.894 cos 2 <) cos The corresponding equation for the angular velocity is = i2 43 - 3 4 8 cos + 5?68 cos 2 The equations for v + v l and are derived independently and so are not convertible into one another by a substitution. These equations give the residuals under II in Table 27, which evidently are not systematic in character. A similar solution for the 1908 observations indicates that these are satisfied by the Faye equation with sufficient accuracy. The formulae in this case are found to be v + Oj = (1.507 + 0.546 cos 2 <) cos ((> % = io57 + 4?O4 cos 2 < The corresponding residuals are shown in Table 28. In the highest latitudes the angular velocity changes very rapidly with the linear, which of course accounts for the large value of the discordance in at 79. i. This point is of low weight. The residual at 44?8 is surprisingly large for a point of such high weight. In view of the simple character of the formula, however, the size of the residuals is in general entirely satisfactory. A comparison of the last formula with the corresponding equations of Duner and Halm will be of interest. These are as follows : Duner . . . = 10.60 + 4.21 cos 2 $ Halm . . . . = 12.03 + 2.50 cos 2 ^ Adams (1908) . . = 10.57 + 4-4 cos2 < The agreement of the first term in the formulae of Duner and myself is remarkable, but probably is somewhat accidental. It represents, of course, the angular velocity of rotation at the sun's pole, and corresponds to a rotation period of 34.0 days. In addition to solving each series of observations separately, I have obtained a mean result for the two sets by combining the values for closely adjoining points of latitude and solving these values by least squares with an equation of Faye's form. Equal weights have been assigned to the two series in the formation of the means and the values then weighted in the solution according to the number of observations. The results are as follows : j) + v 1 = (1.550 + 0.501 cos 2 <) cos | = no4 + 35o cos 2 $ PROBABLE ERRORS. 117 Table 29 contains the values on which the solution is based, and the residuals (observed computed) which are given by these two formulae. These residuals are small in amount, and there appears to be no tendency to systematic effect in sign. This result evidently is due largely to the smoothing-out effect of the 1908 observations. TABLE 28. REPRESENTATION OF 1908 OBSERVATIONS BY FAYE'S FORMULA. TABLE 29. REPRESENTATION OF MEAN RESULTS FOR 1906-1907 AND 1908 BY FAYE'S FORMULA. WEIGHT. A( + *,) A 0.4 21 km + O.OOg + 0-03 4.1 IS - 0.005 0.06 II. 2 12 0.002 0.06 14.9 18 O.OO5 0.06 IQ.2 14 0.016 -0.13 29.8 16 + 0.004 + o 04 34-1 IS 0.000 + 0.01 44-8 i? + 0.023 + 0.28 49.6 16 + O.OII + 0.18 60. i 22 0.012 -0.08 65.0 17 O.OO6 O.OI 75- 17 O.OO3 + O.O2 79.1 7 0.016 0.46 i , , + ,, A(* + V * km km 0.3 2.068 + O.OI7 + 0.13 7.6 2.019 0.004 O.O2 i S-o 95 + O.OOI + O.O2 20.9 839 O.OI7 O.I2 29.8 .672 O.OOI O.OO 35-9 59 O.OII O.I I 44-7 .285 + 0.004 + 0.03 Si-2 .099 + 0.003 + O.O2 59-9 0.836 0.005 O.O9 6S-3 0.683 O.OOI O.O4 7S-o 0.416 + 0.008 + 0.17 79.8 0.275 - 0.003 O.I4 14. PROBABLE ERRORS. A comparison of the probable errors of the results of these determinations with the visual observations of Duner and Halm is rendered rather difficult by the inherent difference in the nature of the methods employed. The photographic results are based upon the measurement of a considerable number of lines, the mean values of which are combined to give a single determination of the rotational velocity. In the work of Duner and Halm only two lines were used, but from eight to twelve settings of the micrometer wire were made upon each line. In the case of the photographic determinations four settings were made in each position of the plate under the measuring microscope. It will be sufficient for general purposes to compare the probable error for a single line on the photographic plate with the probable error for a single visual determination, taken from a series equal in number to the lines on the photographic plate. This should give a marked advantage to the visual results, since the mean of two lines is used, and a large num- ber of settings employed on each of them. In the case of the photographic observations, however, such of the lines as give marked systematic deviations should evidently be omitted when the probable error is formed. Accordingly, six lines of this sort, the behavior of which has already been fully discussed, namely, * 4196, X 4197, X 4216, \ 4257, X 4266, and X 4290.38, are left out of consideration. This leaves a total of fourteen lines for the 1906-1907 series and sixteen for the 1908 series. Plates taken at random from each set give the following values : SINGLE LINE. MEAN VALUE FROM PLATE. 1006-1907 r = 0.015 km r o = ^ 0.004 km 1908 r = i 0.009 r o = -*- 0.002 A series of determinations by Halm in 1903 (s) averaging fifteen observations for each latitude give r = 0.070 km r 0.018 km The earlier series of observations by Duner show probable errors about twice as large as those of Halm, but for the completed series no values are given, though they are undoubtedly considerably smaller than for the previous results. It should be noted that the photographic observations show somewhat larger probable errors in the higher latitudes. Il8 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. A comparison of these values indicates a marked gain in the degree of accuracy of the photographic results over the visual. It is of course impossible to state how much of this gain is due to the more pow- erful spectroscopic apparatus and the larger solar image employed, and how much to the use of the photographic method, but it seems probable that both facts contribute materially to the result. 15. COMPARISON OF RESULTS FOR SUN-SPOTS, FACUL/E, FLOCCULI, REVERSING LAYER, THE a LINE OF HYDROGEN, AND \4227 OF CALCIUM. At the conclusion of this discussion of the rotation of the sun as determined from the displacements of the lines in the reversing layer, it seems desirable to add a comparison with the values obtained by various observers from sun-spots, faculae, and hydrogen and calcium flocculi. Such a comparison with the reversing layer results of Duner and Halm has already been made by Hale and Fox in their discussion of the motion of the calcium flocculi (19), and by Hale in his paper on the motion of the hydrogen flocculi (20). In view of the additional material now available for the reversing layer, a repetition of these values will not be out of place. The quantities, which are given in Table 30, are derived from empirical formulas where these have been obtained ; in other cases they are taken from curves or found by interpolation from the original observations. In the case of the work of Carrington, Spoerer, and Maunder on sun-spots, Duner and Halm on the reversing layer, and Adams on the reversing layer, Ha and X 4227, empirical formula? are available. In the form employed for calculation they are as follows : Carrington Spoerer Maunder Duner Halm Adams (mean of two series) = 11.04 + 3-5 cos 2 4> Adams \ 4227 = 12.5 +2.4 cos 2 < Adams H a = 13.6 + 1.4 cos 2 TABLE 30. COMPARISON OF ROTATION RESULTS FROM VARIOUS SOURCES. = 14.42 - 2.75 sin? = 8.55 + 5.80 cos i = 12.43 + 2 - CI cos2 ' = 10.60 + 4.21 cos 2 ' = 12.03 + 2 -S cos2 ' SUN-SPOTS. FACUL.E. STRATO- NOFF. CALCIUM FLOCCULI. HYDRO- GEN FLOC- CULI. REVERSING LAYER. X 4 227 ADAMS. Ha ADAMS. CARRING- TON. SPOERER. MAUN- DER. HALE AND Fox (KEN- WOOD). Fox. HALE, MOUNT WILSON. MOUNT WILSON. DUNER. HALM. ADAMS, Two SERIES. S IO 15 20 25 3 3S 40 45 SO SS 60 6S 70 75 14.42 14-38 14.29 14.16 14.00 13.81 13.60 I3-38 H-35 14-32 14.26 I4-I5 14.00 13.80 13-57 I3-30 14.44 14-43 14.38 14-3 14.19 14.06 13-91 13-74 14.62 14.61 14.46 14-24 14.18 14.14 13.84 14.70 14-59 14.44 I4-30 14.17 14.02 I3-83 I4-52 14.46 14-33 14.09 13.80 13.82 I3-83 14.42 14.38 14.32 14.28 14.27 14.17 13.98 14.04 13.92 14.6 14.81 14.78 14.68 14-53 14.32 14.06 I3-76 13.42 13-07 12.70 12.34 11.99 11.65 11-35 11.09 10.88 14-53 14.50 14.46 14-37 14-24 14.09 13.90 I3-70 13-50 13.28 13-07 12.86 12.66 12.48 12.32 12.20 H-54 14-51 14-43 14-31 14-13 13-91 13-67 13-39 13.09 12.79 12.49 12.19 11.92 11.67 11-45 11.27 14.9 14.8 14-3 13-7 I3-I 12.7 iS-o 14.9 14.6 H-3 13-9 13-7 SUMMARY OF ROTATION RESULTS. As has already been stated, my own 1908 observations agree closely with Duner's in the higher lati- tudes, but are smaller and nearer Halm's values in the lower latitudes. In Table 31 I have taken simple means for the spot and flocculi results and compared them with the values obtained from my two series of observations on the reversing layer. They are shown graphically in Fig. 2. TABLE 31. SUMMARY or ROTATION RESULTS FROM VARIOUS SOURCES. SPOTS. FACUL.S. FLOCCULI. REVERSING LAYER. O 14.40 14.62 H-55 o 14-54 5 14.38 14.61 14.48 14-51 10 I4-3I 14.46 14-36 14-43 15 14.20 14.24 14.22 14-31 20 14.06 14.18 14.08 14-13 25 13.89 14.14 14.00 i3-9i 30 13.69 13.84 13.88 13-67 35 13-47 13.81 13-39 Faculae Reversing layer Ca Flocculi - Sun spots 14.6 14.4 I4TZ 14.0 13.8 13.6 13.4 I3.E 13.0 <$> 5 10 15 Z0 ZS 30 35" 40 FIG. 2. Curves showing the values of the angular velocity obtained from observations of sun-spots, faculae, calcium flocculi, and reversing layer. Plotted from the results given in Table 31. I2O AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. Attention has already been called by Mr. Hale to the comparatively small values of the angular veloc- ity given by spots (19). The difference at the equator amounts to o?2 as compared with facuke. flocculi, or reversing layer, and in view of the close accordance of the spot observations at this latitude the result is probably to be considered as genuine. Similar differences, as compared with faculae and flocculi, are shown in higher latitudes by the results of Carrington and Spoerer, but the inclusion of Maunder's larger values in the mean conceals this effect. There seems to be a tendency for the reversing layer to give slightly larger values than the flocculi between latitudes o and 20. This may be due, as Mr. Hale has suggested in his discussion, to the possibility that the faculse and flocculi retain the velocities of the lower levels from which they rise, but the differences are small and hardly sufficient to warrant a definite conclusion, espe- cially in view of the considerable discordance among the separate flocculi determinations. Another most interesting consideration is whether there appears to be any difference in the law of the equatorial acceleration in the results given by the observations of the various objects on the sun's surface. This is made especially important by the discovery of the remarkable differences in velocity shown by spectroscopic observations of the hydrogen lines Ha and X 4227 of calcium, as well as observations of the hydrogen flocculi with the spectroheliograph. Unfortunately, the results for both facuke and flocculi are necessarily very uncertain above 30 of latitude. Accordingly, in order to secure as accurate a comparison as seems possible with the material available, I have reduced the results for faculse, flocculi, Ha, and X 4227, by a least-squares solution of Faye's formula, and plotted the corresponding results for every 5 of latitude. The values for the reversing layer are from the formula representing the combined values of the two series of observations. A difference in the rate of change of angular velocity with the latitude will be indicated by a lack of parallelism in the resulting curves, and in order to show this more clearly the values have all been reduced to the common origin of i4?5o. This necessitates the addition of constant quantities to the sun-spot results and the subtraction of constant quantities from the other results. The comparison is shown graphically in Fig. 3. One extrapolation has been made for the faculce and the flocculi. The inspection of these results is of interest in many ways. The spots and the faculae give values which are practically identical throughout, a result which is to be expected from the close relation of these objects to the solar photosphere. Intermediate between these and the flocculi is X 4227, which shows notably less equatorial acceleration. The calcium flocculi show still less, and Ha the least of all, the differences in its case being very great indeed. Apart from the reversing layer these results are quite in harmony with the commonly accepted views of the relative heights of the various gases in the sun's atmosphere. The calcium flocculi, due to the bright reversals of the calcium lines H and K, are usually assumed to lie at a considerable distance above the sun's photosphere, and probably at a higher level than the material producing the blue line of calcium X 4227. Similarly, Ha, which rises to a very great height in the solar atmosphere, gives in addition to very large absolute velocities a greatly reduced amount of equatorial acceleration. In other words, these results are all satisfied by a law of increase of angular velocity and decrease of equa- torial acceleration with increasing altitude above the sun's surface. For the reversing layer the case is very different, however. Here the rate of change of velocity with latitude is the most rapid of any observed, a result which on the basis of the reasoning given above would require that the reversing layer lie below the level of sun-spots and faculae. This almost certainly can not be the case, since the spectrum of faculae, and probably of spots, gives evidence of the presence of the ordi- nary reversing-layer spectrum. At present there is no adequate explanation for this apparent anomaly, but a suggestion is furnished by Wilsing's theoretical discussion of the law of the sun's rotation (21), a memoir the bearing of which on the motion of the strata above the reversing layer has been referred to by Mr. Hale (23). In the course of this discussion Wilsing arrives at the conclusion that owing to internal friction a surface is reached in passing toward the center of the sun at which essentially uniform angular velocity is attained. Similarly, above the solar photosphere another surface of uniform velocity is found, and between these two surfaces the motion is compared by Wilsing to that of "a stream flowing between COMPARISON OF ANGULAR VELOCITIES. 121 two fixed banks." On this basis it is evident that there would be a region at which the rate of change of angular velocity with latitude would be a maximum, and that on either side of this region the change would become less. Accordingly, if we may assume that the reversing layer corresponds to this region of most rapid change, we may expect, on the one hand, the spots and faculae, which are nearer one of the sur- faces of uniform velocity, and, on the other hand, X. 4227, the calcium flocculi, and Ha, whose level is nearer the other surface, to give less equatorial acceleration, the amount diminishing in the order named. The whole question is, however, extremely complex, the quantities concerned are small, except in the case of Ha, and the difficulties involved in the explanation of the differences in the values of the absolute velocities of rotation are correspondingly great. It will hardly be profitable to continue the discussion further until additional observational material has placed the reality of these differences upon a more certain basis. 14.6 14.4 14.2 14.0 Ha at limb Ca Flocculi X 4-ZZ7 Sun spots Faculae Reversing layer 13.8 13.0 0? 5? 15 aO? 25? 30 35! 4-0? 45! FIG. 3. Curves showing variation of angular velocity with latitude for sun-spots, facute, calcium flocculi, reversing layer, X 4227, and Ha.. To facilitate comparison the curves are all reduced to the common origin of I4!so. Differences in the amount of equatorial acceleration are indicated by lack of parallelism in the curves. 122 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. 16. A CASE OF LARGE PROPER MOTION IN THE REVERSING LAYER. Reference was made at an earlier point in this discussion to the disturbing effect of proper motions in the reversing layer upon determinations of rotational velocity. Such motions have frequently been observed in the neighborhood of sun-spots, particularly across the faculae bordering the penumbra, but it appears from the observations described below that they may extend to great distances from spots as well. On September 15, 1908, two spots of considerable size were nearing the west limb of the sun. The larger of the two spots was at 11 north latitude, the other at 6 south latitude. Photographs taken with the spectroheliograph through the a line of hydrogen had shown both spots to be surrounded by immense regions of disturbance, with the filaments nearest the spots giving some evidence of vortical motion. Ob- servations made by Mr. Hale during the passage of the spots across the sun's disk had indicated opposite directions of polarization for the components of the double lines in the spot spectra, thus pointing to oppo- site directions of rotation in the two spots, provided vortical motion were involved. The region between TABLE 32. OBSERVATIONS or PROPER MOTION IN THE REVERSING LAYER. Plate w 173. 1908, Sept. 15, 6 h 5 G. M. T. Measured by L. on T. Distance from Limb 1.5 mm. Quality, good. p-p seci o I72-5 12.8 14.7 75-3 29.6 1.150 0-0 98.0 26.4 27.2 62.8 14.4 1.012 p -24.4 44-8 45-3 44-7 10. 1 1.016 D 7-2 59-9 60.2 29.8 8.3 I.OIO Diameter 170.6 mm 74-9 75-i 14.9 7-4 1.008 Factor 1.018 89.9 90.0 o.o 7.2 1.008 = oo i * = .* = ^ X A V . + ,, A , + ., t A . + ,, s 4208.766 0.165 km 1.805 km 1.942 o 13-79 0.162 km 775 km .907 14.01 0.140 km 1-535 km -655 13-54 4210.494 0.165 .805 1.942 13-79 0.164 794 .926 14.14 0.140 1-535 -655 13-54 4216.136 0.162 .770 1.907 13-54 0.162 .768 .900 13-95 0.140 1-533 -653 13-52 4220.509 0.163 779 1.916 13.60 0.163 -777 .909 14.02 0.140 1.531 .651 13.51 4222.382 0.165 .798 1-935 13-74 0.162 .766 .898 13-94 0.140 1-530 .650 13.50 4233.328 0.164 775 1.912 13-57 0.163 .769 .901 13.96 0.142 i-54i .661 13.59 4236.112 0.164 775 1.912 13-57 0.163 1.768 .900 13-95 0.142 i-S4i .661 13.59 4246.251 0.165 783 1.920 13-63 0.163 1.766 .898 13-94 0.140 1.518 .638 13.40 4250.287 0.165 .781 1.918 13.62 0.161 1.741 1-873 I3-76 0.141 1.528 .648 13.48 4250.945 0.164 .770 1.907 13-54 0.163 1.762 1.894 I3-9I 0.140 i-Si? 637 13.39 4254.505 0.167 .802 1-939 13-77 o.i 60 1.729 1.861 I3-67 0-137 1.483 .603 13.11 4257-815 0.162 747 1.884 13-38 0.163 1.760 1.892 13.90 0-139 1-504 1.624 13.29 = 44?7 = 6* = 75!3 4208.766 0.104 .146 .242 12.41 0.059 0.660 0.729 11.32 0.029 0-363 0-397 II. II 4210.494 0.104 .146 .242 12.41 0.058 0.650 0.719 11.17 0.028 0-351 0-385 10.77 4216.136 0.105 155 .241 12.40 0.059 0.660 0.729 11.32 0.028 0-351 0.385 10.77 4220.509 0.106 -163 -250 12.57 0.058 0.645 0.714 11.09 0.028 0-351 0.385 10.77 4222.382 0.104 .142 -238 12.36 0.059 0.655 0.724 11.24 0.030 0-373 0.407 "39 4233.328 0.107 1.168 .264 12.62 0.059 0-655 0.724 11.24 0.029 0-359 o.393 II.OO 4236.112 0.107 1.167 .263 12.61 0.060 0.665 0-734 11.40 0.029 0-359 0-393 II.OO 4246.251 0.105 1.146 .242 12.40 0.058 0.644 0-713 11.07 0.028 0.346 0.380 10.63 4250.287 0.104 I-I35 1.231 12.30 0.058 0.643 0.712 1 1. 06 0.028 0.346 0.380 10.63 4250.945 0.107 1.165 1.261 12-59 0.059 0-653 0.722 II. 21 0.029 0-358 0.392 10.97 4254.505 0.106 I-I54 1.250 12.48 0.058 0.642 0.711 11.04 0.028 0-345 0-379 10.60 4257-815 0.104 1.131 1.227 12.26 0.060 0.663 0.732 "37 0.028 0-344 0-378 10.58 PROPER MOTION IN THE REVERSING LAYER. 123 the spots was in an extremely chaotic state, owing probably to the intermingling of the disturbances cen- tered about the two spots. Four plates of the region of the spectrum near X 4227 were taken on this date with the rotation apparatus at latitudes ranging from o to 75, in steps differing by 15. Accordingly, for one of the settings at o, a point 6 north of one of the spots fell upon the slit of the instrument ; for another, at latitude i4?9,apoint 4 north of the other spot. In the first case the point fell considerably east of the spot as welt. All of the plates were taken in connection with the investigation of the motionof the calcium vapor giving rise to X 4227, and their density was made greater than usual in order to facilitate settings upon this broad and hazy line. As soon as the measurement of the plates was begun, it was found that the values at latitudes o and 14.9 were very discordant, when compared with those regularly obtained. Therefore a list of lines suitable for measurement was selected, since the regular list could not be used on account of the great density of the negatives, and the plates were investigated separately. The results for these lines are shown in detail in Table 32. The results for X4227 are given in Table 33. TABLE 32. OBSERVATIONS OF PROPER MOTION IN THE REVERSING LAYER Continued. Plate <> 174. 1908, Sept. 15, 6 h s m G. M. T. Measured by L. on T. Distance from Limb 1.5 mm. Quality, good. [Plate constants are the same as for u 173.] = o?o = I4!o = 29^8 A f f + , (. A c tl + Dj A i> + ?, 4208.766 0.161 km 1.762 km 1.899 13-47 O.I 60 km 1-750 km .882 13-83 0.140 km 1-543 km 1.663 o 13.60 4210.494 0.162 1.772 1.909 13-55 0.161 1.761 893 13-91 0.141 1-553 I-673 13.69 4216.136 0.161 1-757 1.894 13-45 0.162 1.770 .902 13-97 0.141 1-543 1.663 13.60 4220.509 0.162 1.766 903 I3-5I o.i 60 1-745 .877 13-79 0.140 1-530 I-653 13-52 4222.382 0.163 1.776 913 I3-58 0.162 .766 .898 13-94 0.142 551 1.671 13-67 4233-328 0.162 1.758 .895 13-45 0.161 749 .881 13.82 0.142 538 1.658 13-56 4236.112 0.162 1-757 .894 13-44 0.162 759 .891 13.89 0.142 538 1.658 13-56 4246.251 0.162 1-752 .889 I3.4I 0.161 -743 .875 13-77 0.142 537 I-657 13-56 4250.287 0.161 1.740 .877 13-33 0.161 .740 .872 '3-75 0.140 515 I-635 13-38 4250.945 0.166 1.794 -931 I3-7I 0.162 749 .881 13.82 0.141 525 1.645 13.46 4254-505 0.162 1-749 .886 13-39 o.i 60 .729 .861 13-67 0.142 -536 1.656 13-55 4257.815 0.163 I-758 -895 13-45 0.162 .748 .880 13-81 0.141 525 I-645 13.46 = 44t7 /> = 62!8 = 75t3 4208.766 0.103 I-I34 1.230 12.29 0.059 0.659 0.728 11.31 0.030 0-374 0.408 11.41 4210.494 O.IO2 1.124 1.220 I2.I9 0.059 0.659 0.728 11.31 0.030 0-374 0.408 11.41 4216.136 0.105 1.141 1-237 12.36 0.059 0.658 0.727 11.29 0.030 0-373 0.407 "-39 4220.509 0.103 1.131 1.227 12.26 0.060 0.668 0-737 n-45 0.030 0-373 0-407 "39 4222.382 O.IO4 1.141 1-237 12.36 0.060 0.668 0-737 "45 0.030 0-373 0.407 "39 4233-328 0.103 1.124 I.22O 12.19 0.059 0-654 0.723 11.23 0.031 0.380 0.414 11.58 4236.112 O.I 06 I.I59 1.255 12-54 0.060 0.664 0-733 11.38 0.032 0-393 0.427 "95 4246.251 0.103 1. 122 1.218 12.17 0.06 1 0-675 0-744 11.56 0.031 0.380 0.414 11.58 4250.287 0.104 I.I32 1.228 12.26 0.060 0.663 0-732 "37 0.029 0-357 0.391 10.94 4250.945 0.105 I.I4I 1.237 12.36 0.060 0.663 0.732 "37 0.029 0-357 0.391 10.94 4254-505 0.105 I.I4I 1.237 12.36 0.059 0.653 0.722 II. 21 0.032 0.392 0.426 11.92 4257-815 0.105 I.I4I 1.237 12.36 0.060 0.663 0-732 "37 0.030 0.369 0.403 11.27 124 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. TABLE 32. OBSERVATIONS or PROPER MOTION IN THE REVERSING LAYER Continued. Plate 10175. 1908, Sept. 15, 7 h io m G. M. T. Measured by L. on T. Distance from Limb 1.5 mm. Quality, good. [Plate constants are the same as for w 173.] = 00 = i4!g = 39:8 A 11 . + ! f A V + , A V ,-M, 1 km km km km km km 4208.766 o.i 68 1.836 1-973 14.01 0.163 1.785 .917 14.08 0.141 547 . 1.667 13.64 4210.494 o.i 66 1.815 13.86 0.164 1.794 .926 14-15 0.141 546 1.666 13.63 4216.136 0.166 1.813 1.950 13.84 0.163 1.782 .914 14.06 0.142 553 I-673 13.69 4220.509 0.166 1.812 1.949 13.84 0.164 1.789 .921 14.11 0.141 543 1.663 13.61 4222.382 o.i 68 1.830 1.967 13.96 0.164 1.788 .920 14.10 0.142 551 1.671 13.67 4233-328 0.167 .813 1.950 13.84 0.164 1.782 .914 14.06 0.142 546 1.666 13.63 4236.112 0.169 .833 1.970 13.99 0.165 1.791 923 14-13 0.142 544 1.664 13.63 4246.251 0.172 .855 1.992 14.14 0.164 J-774 1.906 14.00 0.142 542 1.662 13.62 4250.287 o.i 66 794 13-71 0.163 1.762 1.894 13.91 0.142 539 1.659 13.57 4250.945 0.167 803 1.940 13-77 0.164 1.772 1.904 13.99 0.142 537 I-657 13.56 4254.505 o.i 68 -813 1.950 13.84 0.164 1.771 1.903 13.98 0.143 546 1.666 13-63 4257-815 0.167 .802 1-939 13.77 0.165 1.781 1.917 14.05 0.142 -536 1.656 13-55 = 44?7 0-62!8 = 75?3 4208.766 O.IO2 .123 .219 12. 18 0.058 0.650 0.719 ii. 17 0.028 0-349 0-383 10.72 4210.494 O.IOI "3 .209 12.08 0.060 0.669 0.738 11.46 0.027 0-339 0-373 10.44 4216.136 O.IO2 .122 .218 12.17 0.059 0.659 0.728 11.31 0.028 0-349 0.383 10.72 4220.509 O.IO2 .121 .217 12. l6 0.058 0.648 0.717 11.14 0.027 0-338 0.372 10.41 4222.382 0.102 .120 .216 12.14 0.058 0.648 0.717 11.14 0.028 0.348 0.382 10.69 4233-328 0.103 .121 .217 12. l6 0.059 0-653 0.722 II. 21 0.028 0.346 0.380 10.63 4236.112 0.103 .121 .217 12. l6 0.059 0-653 0.722 II. 21 0.027 0.336 0.370 10.35 4246.251 O.IO2 .no .206 12.05 0.058 0.642 0.711 II.O4 0.027 0-335 0.369 10.32 4250.287 0.102 .110 .206 12.05 0.058 0.642 0.711 11.04 0.028 0.346 0.380 10.63 4250.945 o 104 .130 .226 12.24 0.057 0.632 0.701 10.89 0.028 0.346 0380 10.63 4254.50S 0.104 .130 .226 12.24 0.060 0.663 0.732 n-37 0.028 0.346 0.380 10.63 4257-815 O.IO2 .108 .204 12.03 0-057 0.630 0.699 10.86 0.027 0-335 0.369 10.32 Plate w 176. 1908, Sept. 15, 7 h io m G. M. T. Measured by L. on T. Distance from Limb 1.5 mm. Quality, good. [Plate constants are the same as for u 173.] OO = I4?0 = 2Q!8 A V . + , f A V + , t A V r + r, km km km km o km km 4208.766 0.166 1.816 1-953 13.87 0.163 1.784 1.916 14.08 0.142 i-SSS 1-675 13-70 4210.494 0.165 1.805 1.942 13.79 0.163 1.783 1.915 14.07 0-143 565 .685 13-79 4216.136 o.i 66 1.812 1.949 13.84 0.163 1.780 1.912 14.04 0.142 553 -673 13.69 4220.509 o.i 66 .811 1.948 13.83 0.164 1.789 1.921 14.11 0.141 542 .662 13.60 4222.382 0.167 .820 1-957 13.89 0.163 1.777 1.909 14.02 0.142 551 .671 13-67 4233.328 o.i 66 .803 1.940 13.77 0.163 -771 I-903 13.98 0.142 544 .664 13.61 4236.112 0.167 .809 1.946 13.82 0.165 .790 1.922 14.12 0.142 1-543 663 13.61 4246.251 o.i 68 .817 1-954 13.88 0.163 .768 1.900 13.96 0-143 1-552 .672 13.68 4250.287 o.i 68 .816 1-953 13.87 0.163 .763 1.895 13-92 0.142 1-538 .658 13.56 4250.945 0.169 .824 1.961 13.92 0.164 -771 1.903 13.98 0.142 1-537 .657 13.56 4254.505 o.i 68 .813 1.950 13.85 0.163 759 1.891 13.89 0-143 1.546 1.666 13.63 4257.815 0.167 .802 1-939 13.77 0.162 1.748 1.880 13.81 0.142 I-536 1.656 13.55 = 44?7 = 62!8 = 7S?3 4208.766 O.IO2 125 1. 221 12. 2O 0.059 0.662 0-731 "35 0.028 0-351 0.385 10.77 4210.494 O.IO4 .146 .242 12.40 0.060 0.672 0.741 11.51 0.029 0-363 0-397 II. II 4216.136 0.103 134 .230 12.28 0.060 0.671 0.740 11.49 0.030 0-374 0.408 11.41 4220509 O.IO2 .121 .217 12. l6 0.059 0.660 0.729 11.32 0.029 0-359 0-393 II.OO 4222.382 O.IO2 .I2O .216 12.14 0.060 0.669 0.729 11.32 0.028 0.348 0.382 10.69 4233.328 0.103 I.I27 .223 12.22 0.059 0.656 0.725 11.26 0.029 o.347 0-381 10.66 4236.112 0.103 I.I26 .222 12. 2O 0.058 0.644 0.7I3 11.07 0.030 0-357 0.391 10.94 4246.251 O.IO2 I.II4 .2IO I2.O9 0.058 0.643 0.712 11.05 0.028 0.346 0.380 10.63 4250.287 0.103 1. 121 I.2I7 12. l6 0.060 0.663 0.732 "37 0.029 0.346 0.380 10.63 4250.945 O.IO2 i. no 1. 206 12.05 0.060 0.662 0-731 "35 0.030 0-356 0.390 10.91 4254.505 0.103 I.I2O 1.216 12.15 0.059 0.652 0.721 11.20 0.028 0-345 0-379 10.60 4257.815 O.IO2 I. no 1. 206 12.05 0.058 0.642 0.711 11.03 0.028 0-345 0-379 1 0.60 PROPER MOTION IN THE REVERSING LAYER. 125 The combination of these results gives the values of v + v v shown in Table 33, the normal values in each case being added for comparison. The latter are from the 1908 observations. TABLE 33. PROPER MOTION IN THE REVERSING LAYER. REVERSING LAYER. X 4 227 DISTURBED. NORMAL. DISTURBED. NORMAL. 0.0 km 1-930 km 2.063 km 2.OI km 2.12 14.9 1.899 1.944 1.97 2.O2 29.8 1.666 1.669 i-73 1-75 44-7 1.240 1.289 i-3i 1.36 62.8 0.724 0.740 0.84 0.82 75-3 0.389 0.387 0.48 0.49 At latitude 30 and above that point it is seen that the results obtained from these plates agree fairly well with the normal, although the differences at latitude 44^7 are unusually large. At i49, however, there is a difference of 0.045 km for the reversing layer, and at o a difference of 0.133 km, the values given by these plates being the smaller. The results for X 4227 are very similar. In other words, proper motions of the reversing layer toward the observer at the west limb of the sun of 0.05 km in one case and 0.13 km in the other are indicated, if we assume, as seems altogether probable, that the entire difference is due to the disturbances near the west limb. The direction of motion at the first of these points, i4?9, is in accordance with what would be expected if vortical motion occurred in the northern spot in the direction indicated by polarization observations and photographs with the spectroheliograph. These point to a direction of motion counter-clockwise as seen from above. Accordingly, at a point north of this spot, the motion would be toward the observer, and the rotational velocity reduced. In the case of the second spot an opposite direction of motion is indicated by polarization observations, and we should accordingly expect, for a point north of this spot, motion away from the observer. This is opposed to what is found. It is doubtful, however, whether this lack of agreement is more than apparent. The slit setting in this case was 6 away from the spot, and considerably east of it as well. It also fell on a greatly disturbed region between the two spots, where it is by no means certain that any well-defined direction of motion would predominate. In any case it is clear that a large amount of observational ma- terial would be necessary to settle the question of vortical motion about spots by means of spectroscopic observations of the reversing layer, since the quantities involved are considerably smaller than would be expected, provided any definite motion of this sort, in which the reversing layer shares, actually exists. The important fact as bearing on observations of the rotation of the sun is that large areas on the solar surface may be affected with proper motions of such size as to introduce very serious errors into the results when the areas happen to fall near the sun's limb. It seems very probable that the regions of greatest disturbance, where the proper motions would be largest, are associated with spots ; but observations with the spectroheliograph have shown that such disturbances may also exist where there are no spots. Fur- thermore, an investigation by myself of the small pressure displacements at the sun's limb has led to the conclusion that regions are sometimes found near the center of the sun in which there are ascending currents in the reversing layer, showing motions of as much as 0.2 km. It is very probable that these regions may have a lateral drift as well, in which case they would affect seriously observations of the rotation of the sun. The possible bearing of these results on the two series of observations for 1906-1907 and 1908 has already been noted. Although we should expect differences arising from this cause to be greatest in the zones of spot activity, yet the existence of a few cases of proper motion in the higher latitudes might well affect the rotational values materially, since the observations are not sufficiently numerous to eliminate their effect. A similar cause may perhaps account in part for the difference found by Halm between the two series of observations, 1901-1902 and 1903. In such a case the differences would represent rather the excess of the 126 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. effect of systematic proper motions in one series over that for the other than any real variation in the sun's rate of rotation. The year 1903 was characterized by much greater spot activity than were the two pre- ceding years. Accordingly, it might well happen that if the spots were accompanied by large areas of disturbance, and the points observed did not chance to be symmetrically distributed about them, the aver- age results might be affected by systematic differences. The whole question is doubtful, however, and the main inference to be drawn is that in taking observations to determine the rotation of the sun, regions as free as possible from disturbances should be selected and as large a number of observations as possible be made, in order to reduce the effect of systematic proper motions. 17. DETERMINATION OF THE SOLAR ROTATION WITH THE a LINE OF HYDROGEN. The details of the observations on the a line of hydrogen at the sun's limb and at points averaging 3 mm inside the limb have been given in Tables 15-18 in Part I of this discussion. If we collect the values and form normal places of latitude for the two series, we obtain Table 34. TABLE 34. -MEAN RESULTS FOR THE o LINE OF HYDROGEN. AT LIMB. 3 MM INSIDE LIMB. + , { PERIOD. + , J PERIOD. km days km o days o-S 2.14 15-2 23-7 0.4 2. II 15-0 24.0 14.6 2.03 14.9 24.2 14.6 2.OO 14.7 24-S 2Q-5 I. 7 8 I4.S 24.8 29.8 i-73 14.1 25-5 44.6 1.41 14.0 25-7 45-o 1.38 13.8 26.1 59-9 o-9S 13-5 26.7 60.3 0.90 13.0 27.7 7S-o 0.52 14.2 254 75-5 0.47 13-3 27.1 A comparison of the results in Table 34 shows that the rate of change of the motion is very rapid inward from the limb, and that the points nearer the edge give not only larger absolute values, but also less change of velocity with change of latitude. An effect of this sort would seem very probable from the consideration that the level of effective absorption for points near the limb in the case of an element like hydrogen is probably decidedly higher than that for points inside the limb. Direct evidence of this, although not of very high weight, was furnished by the results obtained from some plates taken so close to the limb that upon two of them the bright chromospheric line was shown. These plates gave very large values through- out, and essentially no evidence of change of angular velocity with latitude. TABLE 35. COMPARISON OF RESULTS FOR o LINE OF HYDROGEN WITH THOSE FOR REVERSING LAYER. Ha. AT LIMB. Ha 3 MM INSIDE LIMB. REVERSING LAYER. r + , J PERIOD. f-t-tij 1 PERIOD. v + v l t PERIOD. km o days km o days km o days 0.5 2.14 15-2 23-7 2. II 15-0 24.0 2.06 14.6 24.6 14.6 2.03 14.9 24.2 2.00 14.7 24-S . I-9S 14.3 2S.2 29-5 I. 7 8 14-5 24.8 i-73 14.1 25-5 1.67 13-7 26.4 44.6 I.4I 14.0 25-7 1-39 13.8 26.0 1.29 12.9 27.9 59-9 o-9S 13-5 26.7 0.92 13-0 2 7 .8 0.81 ii-S 31-3 75- 0.52 14.2 25-4 0.48 13-3 27.1 0.40 10.9 33-1 In order to compare the results of the two series on the a line of hydrogen with each other and with those given by the reversing layer, the values in Table 34 are reduced to the same latitude and collected in Table 35 along with the reversing layer results. The latter are from the 1908 observations. ROTATION DERIVED FROM X 4227 OF CALCIUM. 127 An inspection of the results in Table 35 leads to two important conclusions. First, that the absolute velocity of rotation given by Ha is much higher than that found for the reversing layer. Second, that the law of change of angular velocity with latitude is quite different, the velocity being more nearly uniform, or the equatorial acceleration less, than in the case of the reversing layer. As has been stated previously, it seems probable that the explanation of these results is to be found in the comparatively high level occupied by hydrogen gas in the sun's atmosphere. The change of angular velocity with latitude which, as we have seen, appears to be most rapid for the reversing layer, sun-spots, and facuhe, is almost certainly connected to some extent with the effects of internal friction. This fric- tion no doubt decreases outward from the photosphere, with the result that for the higher gases the ten- dency is toward a more nearly uniform rate of rotation in all latitudes. Similarly, as the effect of friction is reduced, the higher gases tend to acquire greater velocities, the tendency toward orbital motion gradually becoming stronger. It would of course be necessary to go to immense distances from the sun, certainly beyond the corona, before the motion could in any sense be considered truly orbital, but a tendency in this direction might well begin at a comparatively low level. It is of interest to note in this connection that Campbell's result for the rotation of the corona indicates a very short period. Thus Campbell writes (22) : The difference of the determinations for the E. and W. sides is o.i i t.m. (Angstrom), corresponding to a relative velocity in the line of sight for the two sides of 6.2 km, and a rotational velocity of 3.1 km per second. However, I regard this last result as subject to a possible error of at least 2 km per second, partly on account of unavoidable errors of observation, but principally on account of the character of the bright line. A linear rotational velocity of 3.2 km corresponds to a daily angular motion of about 22??, or to a period of rotation of 15.9 days. It seems probable from the Ha results that at the level of even the lowest parts of the corona very little equatorial acceleration would be found. The marked difference in the behavior of Ha at the sun's limb as compared with the violet lines of the hydrogen series makes it probable that a difference in the level of effective absorption is involved. Accordingly, I have made a few attempts to measure the rotational velocity given by the Hy line. The results appear to indicate that Hj gives values averaging about 0.05 km less than Ha, but they are of extremely low weight on account of the difficulty of measurement of this line. The recent studies by Hale and Ellerman of the hydrogen flocculi photographed with the different lines of the hydrogen series would indicate that some such effect might be expected (23). 18. DETERMINATION OF THE SOLAR ROTATION WITH X 4227 OF CALCIUM. The details of the observations on the line X 4227 of calcium and summaries of the results are given in Tables 19 and 20 of Part I. If we combine the values about normal points of latitude, we obtain the results found in Table 36. The reversing layer values from the observations of 1908 are added for comparison. TABLE 36. COMPARISON OF RESULTS FOR \422^ OF CALCIUM WITH THOSE FOR REVERSING LAYER. X4227 REVERSING LAYER. ti + Jij t PERIOD. + , I PERIOD. km o days km o days -4 2.12 15-1 23.8 2.06 14.6 24.6 IS-O 2.O2 14.8 24-3 1.94 14-3 2S-2 29.9 1-75 14.3 25.2 1.67 13.6 26.4 44-9 1.36 13.6 26.5 1.29 12.9 28.0 60.0 0.88 12-5 28.8 0.81 "-S 31-3 74-8 0.49 13-3 27.1 0.40 10.9 33-0 These results indicate that the calcium gas producing X 4227, like hydrogen, moves more rapidly than the reversing layer, and shows less change of velocity with increasing latitude. The differences are less, 128 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. however, than for hydrogen near the limb, and approximately equal to those for hydrogen taken at a dis- tance of 3 mm inside the limb. An investigation of two calcium lines in the less refrangible part of the spectrum has been made by Perot with interference apparatus (17). Preliminary values of the angular velocity given by him are as follows : X 0=0 = 45-7 5349-6 6122.4 15-1 14-7 14.2 14.2 Mean 14.9 14.2 At the equator these results are identical with those obtained here for X 4227, but at 45 they are con- siderably larger. They may, of course, be modified considerably by more complete results, but it seems doubtful whether the entire difference will disappear. If it persists, it would seem to indicate a higher aver- age level for these lines than for X 4227. The broad wings of the latter line point to a region of consider- able density and consequently of low level for their origin, but there can be but little doubt that the central portion of the line rises to a considerable altitude. Moreover, the size of pressure displacements found for the two less refrangible lines at the sun's limb would appear to argue against a very high level origin (24). All three of the lines are found in the spectrum of the chromosphere. VtV, Km 7.20 2.00 1.80 ^^^SSs^, ^5S-. Uniform angular Ha at limb velocity """"-C^T"'-^ l5^> \ 42Z7 Reversing layer 1.60 o^^s. 1.40 ^xj^ ^x 1.20 x^> \x x 1.00 ^ 0.80 \^ 0.60 ^ : ^% \ 0.40 ^ N^ 0.20 X^ Sk VfV, 0.00 "V 9 ID" ZO- 30' 40- 50 i- -, 80* FIG. 4. Variation of radial velocity with heliographic latitude for the different lines observed. The curve for the reversing layer is fronUhe mean results for the two series of observations. The radial velocity curve of a body rotating uniformly with a motion of 15^0 a day is added for comparison. COMPARISON OF RESULTS. 129 19. COMPARISON OF RESULTS FROM ALL THE LINES INVESTIGATED. A remarkable feature of the results for ^ 4227 and the two series on the a line of hydrogen is the sudden increase in angular velocity between 60 and 75 of latitude. Too much stress should perhaps not be laid upon this, since in high latitudes the angular velocity is extremely sensitive to small differences in linear velocity ; and with lines as difficult of measurement as these the entire effect could readily be laid to this source. A change of 0.018 km at 75, for example, would reduce a value of f of i4?o to i3?S- A similar effect, however, was found for the lines of lowest level in the reversing layer, the lines of lanthanum and cyanogen giving exceptionally large deviations in the higher latitudes and in directions opposite to those found for these high-level lines. Accordingly, there seems to be a slight presumption in favor of the existence of some cause toward the pole of the sun which tends to make the deviations from the mean exceptionally large for such lines as give abnormal values. The results for the two series of observations on Ha, for \ 4227, and for the reversing layer are shown graphically in Fig. 4. The fifth curve, indicated by a dotted line, represents the curve of linear velocity of a body rotating with the uniform angular velocity of i5?o a day. It is, of course, the ordinary cosine curve. In conclusion, it will be of interest to give a graphical representation of the results found in this inves- tigation for all the lines studied. Accordingly, I have collected the formulas which represent the solution by least squares of the values of the angular velocity obtained for the reversing layer, Ha, and \4227, and 14.5 14.0 13.5 13.0 IZ.5 11.5 V Ha at limb Her within limb A, 4227 Reversing layer \ 80 90* " 10 20 30 40 50 60 70 FIG. 5. Curves representing the values of the angular velocity given by the empirical formula: derived from the observations of Ha., \ 4227, and the reversing layer. For the last named the mean of the two series of observations is used. 130 AN INVESTIGATION OF THE ROTATION PERIOD OF THE SUN BY SPECTROSCOPIC METHODS. have plotted the results for latitudes o to 75 in Fig. 5. The formula obtained from the mean results for the two series of observations has been employed for the reversing layer. Reversing layer ...... = 11.04 + 3-5 cos 2 $ X 4227 ......... = 12.5 +2.4 cos 2 < Ha (within limb) ..... f = 12.8 +2.0 cos 2 < Ha (limb) ........ =13-6 +1.4 cos 2 ^) The numerical values of the angular velocity resulting from these equations are shown in Table 37 for every 15 of latitude. The values given for the pole are extrapolations based on the formulae, and are, of course, subject to great uncertainty. An investigation of the region between latitude 75 and the pole undertaken with powerful apparatus would prove of great value in deciding many questions connected with the law of the sun's rotation. TABLE 37. FINAL RESULTS FOR THE ANGULAR VELOCITY. REVERSING LAYER X 4227 Ha (INSIDE LIMB) Ha. (LIMB) o 14-54 14.9 14.8 15.0 IS I4-3I 14.8 14.7 14.9 3 13-67 14-3 14-3 14.6 45 12.79 13-7 13-8 14-3 60 11.92 13-1 13-3 13-9 75 11.27 12.7 13.0 13-7 Pole (11.04) (12.5) (12.8) (13.6) 20. GENERAL SUMMARY. The principal results of this investigation may be summarized as follows : 1. Two series of observations of the rotation of the sun made during 1906-1907 and 1908 give results agreeing closely with one another in latitudes o to 50. Above 50 the 1908 observations give smaller values, the greatest difference being at 70 and amounting to about 0.039 km. 2. These differences are probably to be ascribed to small systematic errors in the earlier series of observations arising from the character of the solar image. They may possibly be ascribed in part to proper motions in the sun's reversing layer. 3. The evidence from these results is opposed to the existence of a variation in the sun's rate of rotation, unless the variation be of long period. Not only is there no appreciable difference between the two series of observations in the lower latitudes and the regions of greatest spot activity, but the agreement of the 1908 results with the values of Duner make a variation during the interval very improbable. 4. Both series of observations agree in showing that the lines of different elements give different values of the rotational velocity. Lines of lanthanum and cyanogen give low velocities. These elements are known to lie at low levels in the solar atmosphere. Certain lines of manganese and iron give high velocities. 5. Lines which give systematically large or small values of the velocity appear to give the largest devia- tions from the mean in high latitudes. 6. The 1908 observations are satisfactorily represented by an empirical formula of the Faye type. The 1906-1907 observations show a tendency to systematic residuals with an equation of this form, and require the addition of another term for adequate representation. The combined results for the two series are very closely represented by the formula SUMMARY OF RESULTS. 131 7. The fact that these observations, as well as those of Duner and Halm, are satisfied by the Faye equation indicates that this represents with a considerable degree of accuracy the law of the sun's rotation to within 10 of the pole. 8. A comparison of the probable errors of the 1906-1907 observations with those of the 1908 series indicates a marked gain in accuracy for the latter. The results for both series appear to show a decided superiority for the photographic method over the visual so far as the degree of accuracy is concerned. 9. The displacements of the spectrum lines may be influenced seriously by proper motions of the re- versing layer. These may be very large in the neighborhood of the disturbed regions which are usually associated with sun-spots. A value amounting to 0.2 km has been observed in one such case. It is most important that in observations of the rotation of the sun such regions should be avoided so far as possible. 10. A study of the a line of hydrogen shows that the gas producing this line movesat a muchmore rapid rate than the general reversing layer, and that the change of angular velocity with increasing latitude is very much less. At the equator the difference from the reversing layer is about o5, while at 75 of lati- tude it amounts to over 2.5. 1 1 . The results for the angular velocity obtained from Ha at a short distance inside the limb are appre- ciably smaller than those for the line at the limb. This is probably due to the lower average level of the gas involved in the formation of the line within the limb. 12. The line X 4227 also gives decidedly larger values of the rotational velocity than do the lines of the reversing layer. The values are, however, smaller than for Ha at the sun's limb, and not far from equal to those for Ha within the limb. The equatorial acceleration is considerably greater for X 4227 than for Ha at the limb. 13. The observations on both Ha and X 4227 appear to indicate an increase in the angular velocity near the sun's pole. This is the converse of the result found for the lines of the reversing layer which give abnormally low values, and may perhaps be a genuine effect. 14. The comparison of the results on Ha, X 4227, and the lines of the reversing layer shows that the observations are all satisfied by a law of rotation in which the velocity increases and the equatorial accelera- tion decreases with increasing distance outward from the sun's surface. The cause of this probably lies in the effects of friction in the lower portions of the solar atmosphere. 15. Comparison with the results for sun-spots, faculae, and the calcium flocculi gives the following sequence in order of decreasing equatorial acceleration : spots and faculas, X 4227, calcium flocculi, Ha. The reversing layer, however, shows a greater amount of equatorial acceleration than any of these. If we assume, in accordance with Wilsing's theory, that there are two surfaces of constant angular velocity in the case of a rotating body such as the sun, it is possible that the reversing layer may lie in the position where the departure from this condition is a maximum. On this basis the spots and faculae which lie near the inner surface of uniform velocity, and X 4227, the calcium flocculi, and Ha, which lie nearer the outer surface, would all show less equatorial acceleration. I am under the greatest obligation to Mr. Hale for many suggestions during the progress of this inves- tigation and for a deep interest in it. Among the numerous advances in solar spectroscopy made possible by his design and construction of the tower telescope is to be included the marked gain in accuracy of the later series of observations of the rotation of the sun. I am also greatly indebted to Miss Lasby and to Miss Waterman, of the Computing Division, for aid in the measurement and reduction of the plates. The measurement of many of the plates has been carried out by Miss Lasby alone, and a large part of the great labor involved in their reduction and in the solution of the empirical formulae has been divided between Miss Lasby and Miss Waterman. 132 BIBLIOGRAPHICAL REFERENCES. BIBLIOGRAPHICAL REFERENCES. 1. VOGEL, " Spectralanalytische Untersuchungen an der Sonne," Astronomische Nachrichten, 78, 248, 1872. 2. YOUNG, "Observations on the Displacements of Lines in the Solar Spectrum caused by the Sun's Rotation," American Journal of Science, Third Series, 12, 321, 1876. 3. LANGLEY, " A proposed New Method in Solar Spectrum Analysis," American Journal of Science, Third Series, 14, 140, 1877. 4. CORNU, "Notice sur les Raies Telluriques du Spectre Solaire et en particulier sur le Groupe a," Bulletin Astronomique, I, 74, 1884. 5a. DUNER, "Recherches sur la Rotation du Soleil," 1891. 5b. DUNER, "TJber die Rotation der Sonne, zweite Abhandlung," Nova Ada Regies Socielalis Scientiarum Upsaliensis, Series 4, I, No. 6, 1906. 6. "Mr. Jewell's Researches on the Solar Rotation," Astrophysi- cal Journal, 4, 138, 1896. 7. CREW, "On the Period of the Rotation of the Sun as Deter- mined by the Spectroscope," American Journal of Science, Third Series, 35, 151, 1888, 38, 204, 1889. 8. HALM, " Spectroscopic Observations of the Rotation of the Sun," Transactions of the Royal Society of Edinburgh, 41, Parti, No. 5, 1904. 9. HALM, " Ein Beitrag zur Bestimmung der Rotation der Sonne," Astronomische Nachrichten, 173, 294, 1907. 10. ADAMS, "Spectroscopic Observations of the Rotation of the Sun," Contributions from the Mount Wilson Solar Observa- tory, No. 20 ; Astrophysical Journal, 26, 203, 1907. 11. ADAMS, "Spectroscopic Investigations of the Rotation of the Sun during the year 1908," Contributions from the Mount Wilson Solar Observatory, No. 33; Astrophysical Journal, 29, no, 1909. 12. HALE AND ADAMS, "A Photographic Comparison of the Spec- tra of the Limb and the Center of the Sun," Contributions from the Mount Wilson Solar Observatory, No. 17; Astro- physical Journal, 25, 215, 1907. 13. HALE AND ADAMS, "Second Paper on the Cause of the Char- acteristic Phenomena of Sun-Spot Spectra," Contributions from the Mount Wilson Solar Observatory, No. 15; Astro- physical Journal, 25, 75, 1907. 14. HALE, "Solar Vortices," Contributions from the Mount Wilson Solar Observatory, No. 26; Astrophysical Journal, 28, 100, 1908. 15. ADAMS, "Preliminary Note on the Rotation of the Sun as Determined from the Displacements of the Hydrogen Lines," Contributions from the Mount Wilson Solar Observa- tory, No. 24 ; Astrophysical Journal, 27, 213, 1908. 16. HALE, "The Tower Telescope of the Mount Wilson Solar Observatory," Contributions from the Mount Wilson Solar Observatory, No. 23; Astrophysical Journal, 27, 204, 1908. 17. PEROT, "Sur la Rotation du Soleil," Complcs Rendus, 147, 340, 1908. 18. EVERSHED, "Solar Eclipse of 1900, May 28. General Dis- cussion of Spectroscopic Results," Philosophical Transac- tions, A, 201, 457, 1903. 19. HALE AND Fox, "The Rotation Period of the Sun as Deter- mined from the Motions of the Calcium Flocculi," Publi- cations of the Carnegie Institution of Washington, No. 93, 1908. 20. HALE, "Preliminary Note on the Rotation of the Sun as Determined from the Motions of the Hydrogen Flocculi," Contributions from the Mount Wilson Solar Observatory, No. 25; Astrophysical Journal, 27, 219, 1908. 21. WILSING, "On the Law of the Sun's Rotation," Astrophysical Journal, 3, 247, 1896. 22. CAMPBELL, "The Wave-Length of the Green Coronal Line and Other Data resulting from an Attempt to determine the Law of Rotation of the Solar Corona," Astrophysical Journal, 10, 186, 1899. 23. HALE AND ELLERMAN, "On the Nature of the Hydrogen Floc- culi and their Structure at Different Levels in the Solar Atmosphere," Proceedings of the Royal Society , A, 83, 177, 1910. 24. ADAMS, " An Investigation of the Displacements of the Spec- trum Lines at the Sun's Limb," Contributions from the Mount Wilson Solar Observatory, No. 43; Astrophysical Journal, 31, 30, 1910. UNIVERSITY OF CALIFORNIA LIBRARY BERKELEY Return to desk from which borrowed. This book is DUE on the last date stamped below. AST RCNDMY LIBRARY LD 21-100m-ll,'49(B7146sl6)476 UNIVERSITY OF CALIFORNIA LIBRARY