: C V' c < vs*^ ^- T ' .fK.^-.C?^ " " <'< ij*). ^ r .,-.* .'< U . .. '- <: < v,.'<^ >stcni;itic errors to which concluded right ascensions are liable 5 Plan lor el i mi until it; these errors 7 Kate of tin 1 Kescels clock 7 Kffcct of temperature on this rate 7 Kllect of the barometric pressure 10 I '.Meet of the galvanic current 10 Magnitude of the irregularities of clock rate 1(1 Mode of detecting the systematic errors of the adopted star positions 10 Formation of the ei| nations of condition 11 Solutions of the equations 18 Discussion of the results 19 ( 'Directions to the position of the equinox and the obliquity of the ecliptic 5JO Concluded systematic correct ion to the adopted positions of the clock stars 21 Comparison of right ascensions observed directly and by rcllection 22 Computation of corrections to the right ascensions of the standard stars 22 Discussion of differences between the results of the transit anil circle 26 Hight ascensions of I'olaris 2r CHAPTER 11. POLAli DISTANCES. Preliminary remarks on measured polar distances 33 Individual results for corrections to polar distances of stars 38 Concluded mean positions of standard st a rs for the epoch 1870.0 :FJ Comparison of the preceding polar distances with those of other catalogues 43 K'emarks on these comparisons 45 POSITIONS OF 1TNDAMENTAL STARS ftTIXyiBSZTH OBSERVATIONS .MADE AT THE UNITED STATES NAVAL OBSERVATORY YEAKS ISOJi TO 1867, INCLUSIVE. CHAPTER I. 11IGIIT ASCENSIONS. Tin- agreement between the right ascensions of (lie fundamental stars, resulting from tin- work if tin- different e>hscrvateries, which have of late years made them a subject of regular observation, is very close, and well illustrates tlie approach to perfection which the art of practical astronomy has made. Still, the small outstanding differences are greater than can result from the chance errors of individual observations, thus indicating that hidden sources of systematic error still exist. A classiiication of the differences, with respect to the, positions of the stars, show that they arc mainly a function of this element. In fixing the positions of the stars, one of tiie efforts of the astronomer will be to look for and eliminate every cause which can introduce into his determina- tions errors depending on the position of the stars. The possibility of emus depending on the right ascension of the stars being introduced and perpetuated has been pointed out by different astronomers, and especially by Mr. Watford, in the monthly notices of the Royal Astronomical Society for October, 18(51. The existence of this class of errors is more especially to be feared, because under the system of reducing observations in right ascension, now almost universally adopted, they will tend to perpetuate themselves when once introduced. .Moi co\ IT, owing to the diurnal and annual inequality in the conditions to which the observer and the instrument necessarily, and the clock generally, are subjected, the original introduction of the class of errors referred to is very easy. A mathematical examination of the, law, according to which they will be perpetuated, may not be uninteresting. In the- system of reduction now generally adopted, the mean of all the clock stars observed b\ one- observer during a tour of duty is assumed to lie free from error. Whatever error this mean maybe affected with, the same error will affect the mean of the concluded positions. The alge- braic aggregate of the errors in the adopted positions will be distributed among the concluded positions. If the adopted clock rate' be correct, this distribution will be a uniform one, otherwise it will vary with the position of the star in the group. Suppose, now, that the adopted positions are affected with an error of the form n sin , the error of the concluded posi- tion of the star compared will be represented by ~np Tw ' To change the terms of this fraction into definite integrals, we have only to multiply each of them by da, and substitute / for I. The fraction thus becomes fnp da fn d a Put for the right ascension of the star, the error of whose concluded position is sought, and a for the right ascension of any star with which it is compared. Then, on the above hypothesis, we have *=||*d=(-*o)}j the sign being yo taken that the difference ot right ascension shall always be negative. The factor c depends on the entire number of observations, and may be supposed equal to unity, as it disap- pears from the fraction. Substituting this value of n, and putting c for the final error in the. con eluded position of the star resulting from the errors in the adopted positions of the clock stars, we have J* C" (i~ u o "f" ")j"' tt "t~ I !*o ^ " Jo 7*"o /'"c Jo i ~ " /o The value of the denominator of this fraction is i*. Let the adopted right ascensions of the clock stars now be affected with a periodic error sin + b cos + a' sin '2 a -f b' cos 2 Tut a = fe cos fi, b = fc siii ^9, ft' = k' cos ft', b' = k' siii ,5', x = a + ft, X' = 2a + ft';' which gives p = Tc sin x + k' siii x', The substitution of these values reduces the numerator of c to the form POSITIONS OF FI'NDAMKNTAI. STAlis. The value of tlio tirsl term of tliis expression is -t sin (a + ,3); that ol' tin- second (li--)Jtsiu( + ,;): th;it of tin- third vanishes, ; uid that of the fourth is /.-' sin (1> C + ,;') The \alue ol' r therefore lieconies 1H- sin ( or, writing for , so that now re])resents the right ascension of any star, the position of which is determined by observation, S I e = -^j- (a sin a + ft cos ) -f- , (n 1 sin 2a + ft' cos li) . It appears, then, that in the case supposed, that in which the groups are of a uniform length of six hours, and the clock stars are scattered uniformly through each group, each revision of the fundamental catalogue will tend to diminish the error of single period by rather less than one-ufth, and that of double period by more than one half. The latter will therefore be cut down much more rapidly than the former. In addition to this, it may be noted that errors of single, period are those most likely to have found entrance into the original catalogue, arising, as they do, from the ett'ect of the diurnal change of temperature upon the instrument and the clock. It is also to be remembered that this same cause may perpetuate the errors in question. It is true that the effect of a uniform diurnal change will be eliminated from a symmetrical year's work. But the diurnal change of temperature is not uniform throughout the year, and it is also unsafe to assume that its ett'ect upon the clock is the same in all seasons. This same uncertainty will att'eet the results of comparisons of single stars or groups of stars. The comparison must alwa\s be made with a clock rate deduced from its change of error during a period of at least twenty-four hours, while the interval of comparison is only a fraction of a day, during which the clock rate may be systematically different from its mean rate during the twenty- four hours. In arranging the transit circle observations for 1800 and 1807, the following arrangements were planned as necessary to a reliable determination of the possible systematic error in the adopted right ascensions of the clock stars of the form a sin + /J cos : 1. That the clock should be placed in a position where it would be tree from all diurnal ine- quality of temperature. '_'. That when practicable the same observer should observe as many as six clock stars between -I' 1 and .'!'' of the day, and a corresponding group between O' 1 and l.V' mean time of the night. Also, that similar combinations of groups twelve hours apart should be made in the morning and evening when practicable. The systematic errors would then be of equal magnitude, and of oppo- site signs in each pair of groups compared. K.s continuing the observations through an entire year all regular diurnal inequalities arising from the observer or the instrument would be elimi- nated. And, by using the instrument in opposite positions during the two years, all diurnal ine- qualities in its collimation, whether regular or irregular, will be eliminated. Kate of the clwJc. During the year 18G(i the Kessels clock was in the superintendent's room, where it was supposed to be tree from all appreciable diurnal inequality of temperature. This con- dition was well fulfilled, except during the summer months, when it was found that the night temperature, as indicated by a pointer on the pendulum rod, was about 5 lower than the highest day temperature. As such a change might be deleterious, the clock was, in February, 1807, removed to a niche in the base of the great pier of the equatorial, where its temperature varies but a very few degrees during the entire year. Deeming it advisable to test the rate of the clock under changes of temperature as severely as possible, it was. during the months of November and December, ISOC-flj^aaed to changes of it^S^s [VIXYl&SXTTl 8 POSITIONS OF FUNDAMENTAL STARS. temperature several times more wide and rapid than any it had met with in actual use, while its changes of rate were determined by comparison with the standard mean time clock in the chro- nometer room, which had about as even a rate; as the Kessels clock. The changes of temperature were effected by closing the door of the room, opening the windows, and cutting oil' the heat for periods of one day or more during exceptionally cold weather, and reversing the process when the temperature nearly ceased to fall. The clock comparisons wew made at irregular intervals. The results are presented in the following table, which gives : The mean dates and sidereal times of coincidence of beats of clocks. The sidereal interval following each comparison. The reduction of this interval to solar time. The length of the sums of one or more of these intervals in hours. The relative loss of the Kessels (sidereal) clock during these intervals. The resulting daily losing relative rate of the sidereal clock. The mean reading of the temperature pointer during the rate-interval. Each unit of r corre- sponds to about .'5 Fahrenheit. Menu date. Sidereal time of coin- cidence. Sidereal intervals. Reduction to solar time. Intervals of time. Relative lossol'sid. clock. Relative daily rate T 1866. /I. Ml. . /I. Ml. 8. X. /i. V. K. Nov. 25. 9 13 43 33 8 8 15 79. 988 8.1 .012 . 030 + 3.2 26 21 51 48 ii 30 38 6.002 22 28 26 334 29.991 3.7 .(MIT .047 + 1.8 1 31 30 3 58 46 39. 117 5 30 1C 2 49 44 27.807 6.8 .076 .268 1.4 8 20 12 36 13 4 16 13 1 49 50 41.974 17.994 4.3 .026 .144 - 3.4 14 26 3 289 20. 995 4.0 .011 .066 1.9 27 16 34 12 2 44 51 27. 006 2.7 + .006 + .053 + 1.0 19 19 3 3 52 7 38.027 3.9 + .027 + .106 + 1.8 23 11 10 Dco. 2. 9 13 47 41 3 27 27 33. 986 3.4 .014 . 1)1)8 0.3 3 17 15 8 2 32 32 24. 989 2.5 .011 .108 0.5 19 47 40 6 24 25 62. 977 6.4 .023 .088 + 1.3 2 12 5 22 17 27 219. 109 22.3 + .109 + . 115 + 2.5 4 29 32 13 5fl 45 137. 082 13.9 + .082 + .142 + 2.8 14 26 17 10 28 55 162.010 16.5 + .inn + .015 + 3.5 5 6 55 12 . 11 22 54 48 16 52 28 165. 868 16.9 .132 .187 - 4.4 15 47 16 7 37 42 74. 983 7.6 .017 . 054 8.3 12 23 24 58 15 15 14 149.939 15.3 . 081 .096 9. 5 14 40 12 II 51 :,5 8.996 15 35 7 4 28 28 13. 981 5.4 .023 .1(15 0.2 18 20 3 35 3 51 58 :!8. 003 3.9 + .003 + . 018 j- 1. 3 23 55 33 15 34 25 33.061 15. 6 + .081 + . 124 0. 15 29 58 4 59 18 49. 033 5.0 + . 033 + .159 +0.8 14 20 2!) l(i 3 27 28 33. 988 3. 5 .012 .082 23 56 44 15 12 21 15 15 37 3 27 31 150. 002 33. 997 15. 3 3. 5 + .002 .003 + .003 -- 5.5 . 021 15 18 39 52 POSITIONS OK KfNDAMKNTAL STARS. 9 The probable result of these comparisons is that the losing daily rate of the clock increases by O s .()4 for each unit of increase in r. or by O s .0i:$ for each rise of 1 in flic temperature. If we suppose a periodic diurnal change of (5 in the temperature, or 3 on eacli side of the mean, the resulting inequality in the clock rate will be ilt < being the inequality of clock correction, and the unit of t being one day. Integrating, we have for the resulting inequality in the clock error, and in the reduced right ascensions of stars, cos = O a .OOG cos The discordance of the results is such as to leave the magnitude of this small correction doubtful. The rates were therefore compared with the actual recorded changes of temperature during the summer of ISiiii,* and the result was that the effect of change of temperature was not nearly so great as this, and was, indeed, in the opposite direction. The temperatures and rates are compared in the following table: Limiting ilatrs. Mran rates bet. (lairs. Mean tem- peratures. d. h. 8. o l-(*i. May 23 12.4 + 0.25 64.6 25 5.5 + 0.07 70.5 28 10.6 + 0.14 65.6 31 11.0 + 0.09 71.0 June 4 I Mi + 0.04 74. 5 18 14. + 0.06 6!. '.' 20 12. 6 + 0. 12 72.0 21' 12.0 + 0.14 75.8 23 10. 4 + 0. 12 81.6 26.9 5.7 + 0.00 75. 1 28. 9 4. 8 + 0.13 72.1 July 3 11.6 + 0.11 80.2 8.9 5.1 + 0.00 76.6 13 15. 1 + 0.01 84. H 19 11.4 Taking the differences of the successive numbers in the columns of rate and temperature, we have a series of changes of rates corresponding to changes of temperature. If we change the signs of the corresponding pairs in which the temperature change is negative, and then take the sum of each series, we find Sum of changes of temperature 60 Sum of changes of rate 0. R 26 The daily rate, therefore, appears to diminish by O s .004 for each rise of 1 in the temperature. The apparent difference between the e fleet of natural and artificial changes of temperature may be due to the greater rapidity of the latter. In a rigorous investigation the rate ought to IM> supposed to depend upon the rate of change of the temperature, as well as the absolute amount of the latter. In a mercurial pendulum such an effect would be likely to arise from the different degrees of rapidity with which the mercury and the rod would answer to changes of temperature. The experiments just detailed seem, however, to show that ill the Kessels clock the effect is very small, if not altogether insensible a result not improbable in the case of a gridiron pendulum. found in Washington Observations for IHIiti, Introduction, pp. xx.xix ami xl. 10 POSITIONS OF FUNDAMENTAL STARS. I conclude that the effect of the diurnal change of temperature to 'which the clock was actually exposed may be safely pronounced insensible. Effect of the barometric pressure on the clock. During the month ending February 7, 18C7, the barometer was subject to unusually wide, and rapid fluctuations. The comparison with the clock rates indicated an increase of O s .27 in the daily losing rate for every inch in the rise of the barome- ter. This correction has not been employed, as it can give rise to no systematic diurnal inequality. Effect of the galvanic current. An opinion has prevailed that the passage of the galvanic cur- rent through the pendulum might affect the clock rate. This was tested by throwing the current on and off during alternate intervals of from 4Jto 13 hours, and comparing with the mean-time clock at each change. The result was 8. With battery on the mean relative hourly rate was 0.038 With battery off it was 0.040 Not knowing any way in which the current could appreciably influence the motion of the pen- dulum, I regard this difference as accidental. Irregularities of clock rate. During several months from April, 1867, observations were made with great regularity. This period was divided into intervals of as near ten days each as practica- ble, the dividing points being epochs of determination of clock error. The errors "thus arbitrarily selected were interpolated to the times of such intermediate determinations as were three days or more distant from each end of the period, and compared with these determinations. The mean dis- cordance was O s .12. It appears, then, that if the clock error were determined but once in ten days, the intermediate errors would average about OM2 during the period in question. But I think that during this period the rate was more regular than the average one, and that the mean result for the two years would be from 8 .1(5 to OM8. As the clock corrections are published in full in the introduction to each volume of observa- tions, it seems unnecessary to repeat the data on which these results are founded. A diurnal change in the pointing of the instrument will have the same effect as one in the clock rate. The collimation error is known to undergo a change of 8 .003 for every change of 1 Falnvn- .heit in the temperature. A regular diurnal change in the pointing of the instrument may, therefore, be inferred. Its effect will, however, be eliminated from the mean of the results of the two years by the reversal of the instrument. There are few results for diurnal change of level, it being considered very improbable that there should be such a change. These few do not indicate such a change. A diurnal change of azimuth can be most certainly detected from the observed transits of Polaris. Its discussion is, therefore, deferred for a subsequent section. Having considered the sources of diurnal inequality, the possibility of which may be seen a priori, we now proceed to the discussion of the observations of stars. The method of discussion is founded on the consideration that there may be a systematic difference between the clock correc- tions determined at different times of the day. Such a difference would result from a regular diur- nal change either in the clock, the instrument, or the personal equation of the observer. However improbable its existence may seem, the question of its reality is to be finally settled by the observa- tions themselves. Let us, then, consider the transits of two groups of stars several hours apart. We compare the observed sidereal interval between the transits with the computed difference of right ascensions. The clock rate being supposed accurately known, the difference between the observed and computed intervals may be due to systematic error in the right ascensions of the two groups of stars, and to changes in the observer or instrument. The first source of error will be con- sidered to depend on the right ascension, and to be of the form a sin All + !> cos All; the second will be supposed to depend on the hour of the solar day. In any one day it will be impossible to distinguish between the effects of these two causes. Hut, in the course of a year, the first cause will undergo ;>(!( changes while the second will undergo 305, and the effects may, therefore, be completely separated. Since the second cause may not change regularly in the course of the day, the latter will be 1'OSITIONS OF l<'rM>AMKNTAI. STAKS. 1 1 divided into six parts, in each of wliicli the second elfeet will have separate and independent values. The ilala have, therefore, been divided into three classes, as follows: 1. Comparisons of groups of stars observed in the forenoon, with corresponding groups observed by the same observer during the evening following;'. "2. Similar comparisons in which the first group was observed in the afternoon, and the second near or soon after midnight. ;{. Similar comparisons in which the lirst group was observed in the early evening, and the sec- ond in the early morning. . Each difference between the observed and computed intervals of a pair of groups gives an equa- tion of the form d = a + ma-\-nb, where J, excess of computed over observed interval. , amount by which the lirst group is systematically observed too late, as compared with the sec- ond, or the amount by which the observed interval is systematically too small. M,n, differences between the mean values of sin a and cos for the two groups. The data for the separate comparisons are given in the following table, which shows (1.) The date, the day beginning with the tour of duty of the observer. (li.) The initial of the observer. (3.) The sidereal hour corresponding to the mean of the first group of stars. (4.) The number of stars in the group. (.">.) The mean correction in hnndredths of seconds to the computed right ascensions of tl;e stars of the group. In the year 1866 these computed positions are taken from the American Ephemeris, without correction, and the mean given is simply that of the " miscellaneous corrections" in the last column of the printed observations. In 1867 the corrections refer to the adopted positions, and are the mean excesses of the "adopted" over the "apparent" clock correction. (6,) (7,) (8.) The corresponding quantities for the opposite group of stars. (9.) The values of J, or the excess of the computed over the observed difference of right ascen- sion of the groups. A is the difference between columns (5) and (8), corrected for the change in the collimation of the instrument due to the change of temperature between the times of observation. J forms one side of the equation of condition of the form already given, only that in compari- sons of the second and third classes is replaced by /Sand y respectively. In columns (5,) (8,) and (9) the units represent huudredths of seconds of time. 12 POSITIONS OK FUNDAMENTAL STARS. Date. Obs. Hour. No.of stars. Mean correc'i). Hoar. No.of stars. Mean ronvc'n. Equation of condition. 1866. January 9 R. 1.9 2 + 6 14.1 2 + 4 + 3 = : 7 + 1.0 a + 1. 6 ft H H. 21.0 3 1 6.8 4 2 + 3 = - 1. 5 + 0. 9 31 N. 19.1 3 + 3 7.0 3 y + ll = a - 1.7 + 0.6 31 N -22.1 3 7, 10.6 3 + 5 - 11 = /3 - - 0. 9 +1.5 February 1 R. 19.1 2 + 5 7.0 3 + 6 = - - 1.7 +0.6 1 R. 23.9 3 1 11.3 3 + 3 - 8 = - - 0.9 +1-7 2 H. 22.8 2 2 12.0 4 3 + 3 = 0. 3 +1.7 8 T. 0.0 3 + 3 12. 9 3 1 + 6 = y + 0.3 +1.8 6 H. 18.9 5 + r, 5.9 6 4 + 10 = a - 1.7 +0.3 6 H. 0.8 5 -' 2 14.0 3 3 + 3 = 7 + 0.7 + 1.5 16 H. 18.3 . 4 + 1 5.9 3 3 + 5 = a - 1.8 0. 1(> H. 1.3 3 1 11.4 5 + 2 -2 = y + 0.2 +1.7 17 T. 20.8 3 + 4 9.5 2 8 + 13 = a - 1. 3 + 1.3 20 R. 1.0 4 + 4 12.4 3 2 + 8 = + 0.4 + 1.7 21 T. 20. 7 2 + 6 10.0 3 6 + 13 = a - 1.2 +1.3 26 H. 18.6 3 + 3 7.2 4 4 + 8 = a . 1.7 + 0.5 March 5 H. 1.9 2 + 10 13.0 6 3 + 15 = ;? + 0.8 +1.6 5 H. 6.6 3 6 18.1 2 + 4 - 10 = y + 1. 8 - 0. 2 8 N. 23.2 4 11.3 5 2 + 3 = -- 0. 4 +1.7 8 N. 6.8 2 6 17.9 3 + H -17 = y + 1.7 - 0.2 10 T. 0.2 3 + 4 11.7 5 1 + 6 = 0.0 +1.8 14 N. 21.4 2 3 10.7 4 6 + 4 = o - 1.0 +1.5 16 H. 6.1 2 + 6 18.0 4 2 + 8 = 7 + 1.8 0.0 22 R. 23.8 2 + 4 11.9 4 6 + 11 =a 0. 1 +1.9 26 N. 1.3 3 + 3 13.0 3 + 3 + 2 = + 0.7 + 1.6 27 R. 22.3 2 9 10.5 3 + 2 10 = a 0. 8 +1.5 30 N. 22.1 3 + 4 11.3 3 7 + 12 = o - - 0. 7 +1.5 April 26 R. 0.3 2 + 4 14.0 2 4 + 9 = a + 0. 6 + 1. 5 27 H. 5.0 ^ 3 5 13.5 3 + 2 -5 = + 1.2 +1.1 May 4 H. 0.3 2 4 13.0 4 + 2 - 5 = a + 0. 4 +1.7 12 T. 5.2 4 + 1 15.4 4 + 1 + 2 = + 1.5 +0.8 14 N. 5.4 3 + 2 16.0 4 + 3 + 1=0 + 1.6 + 0.7 15 R. 5.2 2 2 16.1 4 + 3 -3 = + 1.6 +0.7 22 H. 1.3 2 + 8 12.8 5 5 + 14 = n + 0. 6 +1.6 22 H. 5.4 3 + o 17.6 4 1 + 4 = 0+1.7 +0.3 83 T. 0.6 3 + 5 12.6 2 1 + 7 = a + 0. 5 +1.7 24 N. 1.9 2 15.1 3 ^ + 2 = + 0.9 +1.5 24 N. 5.5 3 18.1 3 + 2 + 1=0 + 1.8 +0.1 25 H. 1.1 4 + 1 14.4 2 + 2 = a + 0.9 +1.5 28 N. 6.0 6 1 15. 8 5 + 2 = + 1.6 +0.5 30 T. 1.9 2 3 13.8 2 l = a + 0.9 +1.5 30 T. 7.4 2 14 17.1 3 + 12 23 = + 1. 6 - 0. 1 June 4 N. 7.0 3 7 16.3 3 + 4 -8 = + 1.6 +0.1 8 R. 6.9 3 2 17.8 3 + .7 6 = + 1.8 - 0.2 11 N. 7.5 3 5 18.6 3 + 2 -4 = + 1.8 - 0.6 12 R, 3.7 2 n 15.0 2 3 + 5 = a + 1.4 +1.2 16 T. 3.6 2 15.6 3 + 4 -2 = o + 1.5 +1.2 18 N. 7.6 2 6 18. 5 4 + 3 -6 = + 1.8 - 0.5 22 R. 6.2 4 4 18.0 3 + 1 8 = + 1.9 - 0.1 ( I'OSITIONS OK FUNDAMENTAL STA 13 Hair. 01. Hour. No. of stars. Mean i mi i i-'n. Hour. No.of stars. Mean convc'ii. Equation of condition. L866. .lunc 23 11. 7.6 2 4 15.8 I + 6 - 7 = + 1.6 a + 0. Ib 25 N. 6. II 2 - 10 18.5 3 + 5 -12 = a + 1.9 0.2 26 R. 4.8 2 4 16.4 4 4 3 -5 = + 1.7 +0.8 n II. 14.3 2 4 1.7 S + 5 -9 = 7 0.8 1.7 July 2 N. 4.8 2 + 2 17.4 4 + 5 1 = + 1.8 +0.5 2 N. 13.4 2 !l 1.9 2 4- 2 11 = 7 - - 0.9 1.7 5 N. 5.2 2 6 If.. 7 4 + 1 -5 = a + 1.8 +0.5 5 N. 11.6 2 6 1.6 2 + 8 11 = 7 0.3 1.7 6 K. 4.8 2 4 16.7 3 + 3 -5 = o + 1.8 +0.7 6 K. 14.0 2 4 1.6 2 + 4 - 8 = 7 - - 0.9 -1.7 7 11. 13.4 2 1 2.4 2 + 3 4 = y - - 1.0 1.6 11 T. 5.1 3 16.8 4 + 2 . l = a' + 1.8 +0.6 11 T. i-.'. i; 3 9 21.1 2 + 10 - 16 = 7 + 0. 1 -1.8 111 H. 5.2 4 4 17.2 5 4- 4 -7 = + 1.8 +0.5 a H. ;i. f, 2 - 14 r.t. :, 4 4- 7 -18 = + 1.4 0.1 13 II. 13.7 3 5 1.7 2 4- 3 - 8 = 7 - - 0.9 -1.7 14 T. 5.4 4 4 17.3 4 + 2 4 = + 1.8 +0.5 14 T. I-'..', 3 0.5 3 4 + 7 = 7 - 0.3 -1.8 16 N. f>. 5 3 - 5 18.0 4 4- 3 - 6 = + 1.8 + 0.2 19 K. 5.3 3 3 17.5 3 4- 2 -3 = o + 1.8 +0.3 23 N. 13.6 2 4 1.9 2 - 2 = 7 - 0. 9 -1.7 26 N. 6.2 2 4 18.4 5 + 4 - 6 = + 1.8 - 0.2 26 N. 11.5 4 2 1.1 2 + 1 = - - 0. 2 -1.8 27 H. 11.5 3 6 20.9 3 4 5 -8 = + 0.8 1.5 31 H. f.. 2 5 1 18.9 4 4- 4 -3 = o + 1.8 0.4 August 3 T. 6.6 3 5 18.4 3 + 8 -ll = o + 1.8 0.3 3 T. 12.5 2 1 23.0 2 6 + 8 = 7 + 0.2 -1.8 I N.. 7.0 3 * 3 19.4 4 + 2 - 3 = o + 1.7 0.7 10 H. 7.2 3 7 19.3 5 4- 8 13 = a + 1. 8 0. 7 10 11. 12.0 3 7 1.1 2 4 = - - 0. 3 1.8 15 T. 13.6 2 4 0.2 2 4 + 3 = 7 - 0.4 -1.8 16 R. 7.5 3 5 19.8 4 + 2 5 = + 1.7 0.9 16 R. II. n 2 11 23.2 3 4- 5 - 13 = 7 - 0. 3 1. 7 17 II. 7.2 5 1 19. P 4 2 l = o + 1.7 1.8 17 H. 12.5 3 3 22.6 4 + 3 - 3 = + 0.2 1.7 18 T. 7.3 3 8 19.2 3 + 13 -20 = o + l. 8 0.7 20 N. 7.6 4 7 21.2 4 + 6 -12 = o + 1.6 .1 20 N. 11.4 2 5 0.8 2 + 5 - 7 = 0.0 .8 22 T. 7.6 2 9 21.2 2 + 6 -13 = a+1.5 .1 S..|,i,.|,il.cr 5 T. 13.6 2 4 23.6 2 4 + 3 = -- 0.3 .7 8 T. 9.5 2 14 21.1 4 + 5 -18 = a + 1.3 .4 8 T. 13.1 2 7 0.4 2 4 3 7 = 0.5 .8 12 T. 0.8 2 11 21.0 3 4- 9 -18 = a + 1.2 - .5 13 R, '.'. 6 2 21.2 4 1 + 3 = a + 1.2 .5 14 T. 14.4 2 12 23.8 2 4 2 - 11=0 - - 0.5 .7 15 R. 13.8 2 7 23. 3 + 3 - 7 = 0.2 .7 22 N. 12.4 3 - 5 22.3 4' 4 6 8 = + 0.3 .8 27 28 N. R. 9.8 12.1 3 2" 1 12 23.0 23.5 3 4 + 7 , - 6 = + 0.8 .6 + 6 - 16 = o + 0. 1 .ft 14 POSITIONS OF FUNDAMENTAL STARS. r Date. Obs. Hour. No.of btars. Mean orrec'n. Hour. No.of tars. Mean orrec'u. Equation of condition. 1866. October 3 H. 10.4 3 4 22.3 4 + 8 11 = o + 0.8a - 1.7 6 4 R. 15.6 2 4 0.2 2 + 8 - 9 = /3 - - 0. 8 -1.5 5 H. 10.4 3 7 21.8 4 + 2 7 = + 0.9 1.6 5 H. 14.4 2 3 0.8 2 1 + l = l) + 0.8 -1.6 6 N. 11.0 3 1 22.7 2 + 4 3 = a + 0. 7 1. 8 8 N. 12.3 3 4 0.5 4 + 2 4 = a - - 0. 2 - 1. 8 8 N. 15.1 3 1 1.9 2 + 1 = ,i - 1.2 - 1.5 17 H. 11.4 2 3 0.3 3 + 6 8 = a + 0. 1 -.1.8 17 H. 17.1 4 3 6.2 3 1 + 1 = 7 - 1. 8 - 0. 2 18 R. 15.6 2 + 6 4.4 3 6 + 14 = f) - - 1. 6 . 1. 19 H. 17.7 4 2 5.1 3 + 2 1 = y - - 1. 8 - 0. 4 20 N. -14.1 3 + 3 0.1 4 + 3 + 2 = /J -- 0.5 -1.7 25 R. 13.6 2 6 1.4 3 + 1 5 = a 0. 8 1.7 31 H. 11.0 5 4 22.9 4 3 = a + 0.5 -1.8 November 2 H. 12.2 2 - 11 1.3 3 + 5 - 14 = a - - 0. 5 1.8 2 H. 16.6 4 4.8 3 + 4 1 = p - - 1. 7 - 0. 7 5 N. 12.8 2 + 4 1.9 2 2 + 7 = o - - 0.7 -1.7 7 T. 12.9 2 4 2.5 3 + 9 12 = a 0. 9 -1.7 7 8 12 T. N. N. 17.3 13.5 17.7 2 3 3 - 6 + 10 4.8 2.5 5.0 2 2 4 + 1 + 8 + 2 5 = f) - - 1. 8 - 0. 5 - 7 =a - - 1.0 -1.6 + 10 = /3 - - 1. 8 - 0. 4 13 R. 13.8 2 + 2 1.2 2 + 2 + l = a -- 0.8 - 1.7 17 T. 13.8 2 5 3.3 2 + 7 - ll = o - 1.2 - 1.5 20 R. 13.8 2 5 1.9 3 4 + = a - - 0. 9 1.7 / 21 T. 13.5 4 + 5 2.7 3 6 + ll = a 1.0 1.5 26 T. 14.8 3 + 3 1.5 3 + 3 + 1 = 1.0 1.6 26 T. 18.3 3 + 2 8.0 4 3 + 7 = /3 - - 1.7 +0.6 December 4 R. 19.2 2 4 6.5 5 + 2 4 = /3 1.8 +0. 4 5 N. 14.6 2 + 3 3.3 3 4 + 7 = o - - 1.3 - 1.4 5 N. 19.2 4 + 6 7.4 3 2 + 10 = /3 1. 7 + 0. 7 10 R. 17.0 2 2 3.2 2 3 + 3 = a 1.6 1.0 12 R. 19.1 2 2 6.6 4 + 2 - 2 = /3 - - 1.8 +0.5 20 T. 16.2 3 + 5 2.8 4 8 + 14 = a - - 1.5 - 1.1 20 T. 19.4 4 + 8 7.0 2 10 + 20 = /3 -- 1.8 + 0.7 POSITIONS OF FUNDAMENTAL, STARS. If) Hate. ni,*. Hour. No.,,1 stars. Mean OITCC'II. Hour. No.of St. 'IIS. Mean OITCC'II. Initiation of condition. 1887. January l. r > H. 22. 3 2 J 7.8 2 1 - 2 = - - 1.3 a + 1.36 18 11. 17.9 3 + 1 5.6 4 = o - - 1.8 0.2 19 T. Ukl 8 6.5 2 + 5 - 6 = - 1.8 +0.5 22 H. 22.3 2 4 CM 2 + 2 - 8 = - - 0.4 +1.7 23 T. 1-." 2 + 5 6.9 3 4> + 6 = 1.9 +0.3 23 T. 1.5 2 + 2 11.7 3 2 + 3 = 7 + 0.3 +1.8 24 N. 17.6 4 2 7.5 2 + 6 - 9 = o - 1.8 +0.3 24 N. 22.1 2 + 7 10.7 4 4 + 9 = - - 0.8 +1.7 28 N. 1-. 1 3 + 4 5.4 3 2 + 5 = 1.9 0.1 .".I H. 18.6 2 6 6.5 2 + 4 - 11 = o - - 2.0 +0.2 29 H. 3.2 2 + 5 15.1 2 + 3= x + 1.5 + 1.3 Kcliniary 1 H. 19.1 2 6 6.3 3 + 4 - 11 =o - 1.8 +0.4 5 II. 3.5 3 1 13.6 2 + 7 -9 = y + 1.2 +1.4 6 T. 19.1 3 1 7.2 2 3 + l=a - 1.8 + 0. 7 6 T. 0.4 2 8 12.4 4 + 5 - 14 = y + 0. 1 +1.8 7 N. 19.7 2 4 7.4 2 + 2 -7 = a 1.8 +0. 8 7 N. 22.8 2 2 9.5 2 + 4 - 8 = - - 0.9 +1.7 11 N. 23.5 2 + 2 9.3 3 + 2 - 2 = 0.8 +1.6 12 H. 19.4 3 3 4.7 3 + 8 - 12 = a - 1.7 + 0.1 26 II. 7.4 2 + 2 17.2 2 4 + 6 = y+1.7 - 0.1 27 T. 19.6 3 8.2 2 + 2 - 3 = o 1.6 +0.9 March 18 N. 22.1 2 + 2 9.2 2 + 1 = a - 1.2 +1.5 28 N. 7.1 4 2 19.7 3 -2 = y + 1.7 - 0.8 80 II. 21.8 2 + 2 11.1 2 2 l = o - - 0.8 +1.7 29 H. 2.5 3 - 2 13.5 4 + 2 - 6 = + 1,0 + 1.0 30 T. 21.8 3 10.7 3 l = a - - 0.9 +1.7 April 2 H. 2.9 3 3 12.3 3 + 1 -6 = + 0.8 +1.7 2 H. 9.5 2 + 2 18.6 2 + 2 1 = 7 + 1.6 0.9 3 T. 0.4 2 3 12.1 3 2 -2 = o + 0.2 +1.9 5 H. 2.4 2 2 11.2 2 + 2 -6 = + 0.4 +1.7 6 T. 1.0 3 + 4 12.9 8 1 + 3 = + 0.6 +1.7 13 N. 22.8 2 2 11.1 3 - 3 = a - - 0. 6 +1.8 17 T. 4.4 2 1 15.1 3 + 5 -8 = + 1.5 +1.1 18 II. 0.0 2 2 11.1 3 + 3 - 6 = a - - 0.3 +1.9 18 11. 4.1 2 2 14.0 2 4 = + 1.3 + 1.3 26 H. 2.8 3 5 13.0 4 + 4 - 11 =0 + 1.0 + 1.6 May 9 N. 4.3 5 5 14.1 5 + 4 -12 = + 1.3 +1.2 17 H. 0.4 2 + 2 12.4 4 3 + 3 = a + 0.2 +1.9 18 T. 1.2 2 + 4 14.1 2 + 3 1 = + 0.9 +1.7 18 T. 6.0 3 5 17.1 3 - 8 = + 1.8 + 0.2 23 N. 11.0 7 3 21.4 4 + 2 -6 = 7 + 0.9 1.6 24 II. 1.2 3 li 12.2 5 + 4 - 12 = o + 0. 4 + 1 . - 31 11. 2.3 4 o 14.2 5 + 1 -5 = o + l.l +1.5* June 1 N. 1.6 4 + 2 15.0 2 2 + 2 = a + 1.1 +1.5 1 V (Cs 5 2 1 :>.!) 3 + 1 -6 = + 1.7 +0.3 4 T. 1.9 2 ~" ~~ J 13.8 5 1 -6 = + 1.0 +1.6 4 T. 7.6 2 4 17.4 2 + 12 - 19 = + l.s 0.3 5 a. 1.9 3 13.8 3 + 2 -3 = a + 1.0 +1.7 8 N. 1.6 3 + 3 12.3 3 5 + 7^a + 0.5 +1.7 16 POSITIONS OF FUNDAMENTAL STARS. Date. Obs. Hour. No.of stars. Mean corrcc'n. Hour. No.of stars. Mean correc'n. Ktjnation of condition. 1867. Juno 10 N. 5.2 2 + 1 16.6 2 + 4 - 5 = a + 1.8 a + 0.66. 10 T. 0.8 2 + 3 12.4 2 4 + 7 = 7 + 0.3 +1.9 11 T. 1.4 6 7 13.7 5 -8 = 7 + 0.8 +1.7 11 T. 7.5 3 5 17.4 3 + 8 -10 = + 1.8 0.2 13 N. 3.3 4 + 3 16.6 3 + 2 . ]= a + 1.6 + 1.0 14 H. 4.4 4 7 16.2 5 + 5 - 14 = a + 1.7 + 0. 9 15 T. 0.5 2 + 7 13.6 2 6 13 = y + 0. 6 +1.8 20 N. 4.4 2 5 16.3 3 + 1 - 8 = a + 1.7 + 0.8 20 N. 7.5 2 4 18.4 2 + 8 - 15 = /J +1.9 - 0.5 21 H. .4.1 2 6 15.9 4 + 2 - 10 = a + 1.6 +1.0 21 H. 7.5 2 8 18.5 3 + 9 - 20 = p + 1.9 0. 6 July 1 N. 3.8 3 + 1 17.0 3 1 = a + 1.7 +0.8 2 H. 5.1 3 4 14.0 2 + 6 - 12 = a +' 1. 4 + 0. 1 10 T. 5.3 3 3 16.9 5 1 - 4 = a + 1.8 + 0.5 .11 N. 4.4 3 9 16.8 4 + 6 - 17 = a . + 1.7 + 0. 7 11 N. 8.9 4 8 19.6 4 + 12 -23 = /3 -{ 1.6 1.1 15 N. 5.6 4 1 16.5 3 + 8 -ll = a + 1.8 +0.5 17 T. 5.4 4 8 17. 5 3 + 10 20 = a + 1.8 + 0. 3 17 T. 9.9 3 8 20.3 3 + 8 - 19 = ,3 + 1.3 -1.4 18 N. 9.8 3 3 19.9 3 + 5 11 = p + 1.3 1.3 19 H. 5.6 6 4 18.7 4 + 5 -ll = a + 1.8 0.1 19 H. 10.1 2 8 21.7 3 + 2 - 13 = p + 1. 1 1.6 20 T. 5.4 4 11 18.3 3 + 2 - 15 = a + 1. 8 + 0. 1 22 X. 5.9 5 6 17.9 5 + 5 -13 = o + 1.8 0.0 23 H. 5.2 6 6 18.8 3 + 12 20 = a + 1.8 0.0 24 T. 5.8 3 7 18.6 3 + 7 16 = a + 1. 9 - 0. 1 27 T. 5.5 3 5 18.7 2 + 4 -ll = a + 1.9 0. 30 H. 6.1 3 11 18.7 2 + 6 19 = a + 1. 9 0. 1 30 H. 11.4 2 2 21.6 3 + 10 15 = /3 + 0.7 1.7 31 T. 6.9 2 8 22.0 2 + 4 14 = n + 1.4 -1.1 31 T. 12.6 2 23.9 2 + 2 5 = /3 - - 0.2 -1.8 August 5 N. 8.8 3 4 18.3 3 + 3 9 = a + 1.6 0.8 9 H. 7.0 2 6 17.8 3 + 7 15 = a + 1.8 - 0.2 12 N. 7.6 2 8 20.2 3 + 6 -16 = a + 1.6 -1.0 13 H. 7.4 4 3 20.0 2 + 6 11 = a + 1.6 0.9 23 H. 12.2 2 . 12 22.2 5 + 6 _ 21 = ,3 + 0. 4 -1.7 23 H. 18.7 2 4 (1.2 2 7 + 3 = y 1.9 + 0. 3 26 R. 10.4 2 1 22.0 4 . 4 + /3 + 0.9 -1.7 30 H. 7.5 4 4 19.8 3 + 8 14 = a + 1.7 0.9 31 T. 8.5 2 4 19.8 2 + 5 11 = + 1.6 -1.1 September 4 T. 12.8 3 8 22.8 3 + 4 -15 = + 0.1 -1.8 G N. 10.4 3 . 10 22.9 6 + 4 16 = o + 0. 7 1. 7 11 T. 9.6 3 9 20.9 4 + -17 = a + 1.2 1.4 11 T. 13.3 2 6 0.2 2 + 6 15 = 0.4 1.9 12 N. 8.8 3 14 20.2 6 + 6 -22 = a + 1.5 1.2 12 N. 14.0 2 10 0.3 2 + 9 -22 = -- 0.6 -1.7 13 H. 9.4 4 7 19.6 4 + 6 15 = a + 1.4 - 0.1 13 H. 13. 5 4 4 23.3 3 + 7 _ 14 = - - 0.2 1.8 17 II. 9.8 4 6 21.7 3 + 8 _16 = o + 1.1 1.6 1 POSITION'S OK FUNDAMENTAL STARS. 17 Date. (IllS. Hour. No.of -l;ll~. Menu colTrc'n. lluiir. Xo.or -t:u~. Mi-mi oorrec'n. Kipiiition of condition. 186T. * S'lllclllh'rlf* T. !i. " 4 12 -"-'. ! 9 4 4 -18 = a + 1.0 -1.7 111 V y.7 3 :t 20.8 3 -5 = a + (i.!) -1.7 19 N. ii. i 2 + 4 23.6 2 4 2 = - - 0.5 1.7 22 11. ;i. :; 6 1(1 21.7 5 4 8 -20 = o + 1.2 1.5 24 T. 14.11 2 2 22.8 2 - 5 = - 0.2 1.7 October 1 11. 1(1.2 4 13 91.6 4 4 12 -26 = a + l.ll 1.6 1 H. 1 1.- 4 8 24.2 2 4 12 -22 = -- 0.7 1.6 -' T. 10.7 4 6 . 19.3 3 + 4 -11 = + 1.2 1.2 8 H. 10.6 4 7 22.5 2 4- 10 - 18 = a + 0. 8 1.8 8 H. 14.6 2 2 1.4 2 + 8 - 12 = , a - i.o .1.7 11 II. 10.6 9 G 21.9 3 4 4 - 11 = + 0.9 . 1.6 14 11. 11.4 2 12 21.6 3 4 3 -16=0 + 0.8 1.7 14 H. 15.6 3 4 1.8 5 4 4 - 10 = - 1.2 1.4 1C T. 11.4 2 2 1.6 3 4 4 - 7 = o - - 0.2 1.7 17 H. 15. 9 4 1 3.3 5 2 1 = - 1.5 . -- 1.2 18 A. 15.0 2 3 1.9 3 3 - 2 = - 1.2 l.G 19 T. 11.4 2 7 1.1 4 4 3 - 11 = a - - 0. 1 1. 9 23 H. ir.. !i 4 2.1 3 1 1 = - 1.3 1.3 24 A. 16.3 3 4 1 3.8 3 4- 1 - 2 = - 1.6 1.0 26 11. 12.2 2 9 22.0 3 4- 5 -15 = o + 0.4 1.7 NoYrllllMT f> A. 13.0 2 + 2 22.3 3 4 l = o + 0. 1 - 0. 7 :. A. 15.9 2 + 8 2.4 2 10 + 16 = 0-1.4 -1.3 G T. 15.4 2 5 2.1 3 - 7 = - 1.2 -1.4 15 A. 17.8 9 + 10 6.6 3 1 + 9 = - l.f +0.1 18 H. 13.5 4 2 0.6 3 + 3- - 6 = a - - 0.6 1.7 18 11. 18. 2 4- 2 3.6 2 = - 1.8 -0.6 20 T. 13.6 9 11 1.2 2 4 12 24 = o -- 0.7 1.8 26 A. 14.5 4 - 2 2.9 6 4 2 5 = a-1.3 1.5 30 T. 15.2 3 4 1.5 2 - 5 = o - 1.1 -1.5 Dt'uciuln'r 5 H. 15.6 2 4 2 0.8 2 + 1 = a - 1.0 1.5 5 H. 19.2 7 4.2 2 4 + 2 = - 1.7 - 0.2 7 T. 15.2 3 + 3 1.3 4 (1 + 2 = o - 1.1 - 1.6 7 T. 19.3 3 4- :i 4.0 9 7 + 8 = - 1.7 - 0.1 11 H. 14.0 4 + -I 1.2 4 2 + 5 = o-- 0.9 1.7 !l H. 19.5 :! 4 3 4.4 9 6 + 7=0 - 1.7 0.0 16 H. 1 :,.-.' 4 it 0.8 4 6 + 5 = o - - 0.9 1.6 17 A. 17.0 9 6.0 4 4 + 3 = a 1.8 0.0 19 H. 16.3 2 4 4 1.8 4 4 + 7 = a-1.2 1.4 23 H. 15. 3 5 4 1 2.8 4 = a - 1.4 1.4 26 H. 19.8 2 + 2 6.0 3 2 + 2 = - 1.8 +0.5 18 POSITIONS OF FUNDAMENTAL, STABS. In discussing' these equations the results for the two years arc first treated separately. Equal weight is given to each equation, it appearing that the error, arising from an insufficient number of stars, is generally small. The equations are treated by the method of least squares, except that only the factors 0, 1, and 2 have been used as multipliers. Thus, the following normal equations and solutions are obtained : Class a 1866. 9* 70 a + 32.7 16.4 b = 1.13 40 u + 142.2 a + 1,'3.8 I = 4.04 20 + 7.9 a + 129.0 b + ,'3.99 Solution. 8. a = + 0.007 a = 0.034 b = + 0.034 48 ft + 5.1 a 7.9 b = 0.80 Glass p { 10 ft + 91.G a + 2.9 b = - 2.75 _ 8 ft + 7.5 a + 83.4 b = + 1.98 ft = 0.009 rt = 0.030 b = + 0.020 21 Y 2.6 a 15.16 = 0.83 Class Y { 2 r + 24.9 a + 13.G b = + 0.10 _ 18 r + 17.2 a + 54.0 6 = + 1.48 r = 0.022 = 0.013 & = + 0.031 The small values of a, /9, and f show that during the year 1866 there was no appreciable diur- nal inequality in the apparent course of the stars over the meridian, as measured by the instrument and clock. The mean values of and 6 show that the right ascensions of the American Ephemcris, which are the same with those of Dr. Gould's standard Coast Survey Catalogue, require the systematic correction, _ o.030 sin + 0".030 cos . The corrections applied to this catalogue to obtain the clock correction is of the systematic form 0".008 sin a. so that the correction to be applied to the adopted positions is O s .022 sin a + 9 .030 cos . 1867 Normal equations. 77 + 20.0 a 12.76 = 0.35 Class a <; 31 a + 105.8 a 8.3 6 = - 7.42 _20a 0.4 a + 134.46= + 4.23 Solutions. 8. a = 0.009 a = 0.031 b = + 0.021 f 49/5 2.2 a 18.56= -3.54 Class /? .-> cos . i omliining this with the above correction Iroin the observations for ISiiii, we have, for the -result of both years' work. 0".028 sin + O s .028 cos , or. + O s .0,'!9 siu ( in 1 ') The very large values of ./ and ,; corresponding to the year 1867 are remarkable. They indi- cate that during tliis year stars observed in the day-time seemed to cross the meridian too soon by O s .(l(i.">, when compared with transits at night. Any diurnal inequality in the clock rate during this year has been shown to be out of the question, and it does not seem possible that the instrument could have been subjected to such unequal heating, from any cause whatever, as would change its pointing in right ascension. The inequality is greater in the case of the forenoon observations, made before the sun's rays had had time to heat up the interior of the roof, than in the afternoon. It would therefore appear that the cause is to be sought for in the manner in which observers themselves arc a flee ted by the different conditions under which the day and night observations are made. In the day-time the nervous system is braced by the rest of the preceding night, and stim- ulated by sunlight ; the observations are so few that particular attention can be concentrated on each, and this concentration is the more easy from the Hue and sharp definition of the transit wires upon the bright ground of the sky. As night advances the nervous system becomes relaxed by con- tinned labor; attention is no longer concentrated as during daylight, but is divided among rapidly- recurring observations, and the wires are comparatively indistinct upon the feebly-illuminated back- ground. All these causes will tend toward allowing the observer to let the star slip by a little at night, and this is the very result which is indicated by the sensible magnitude of the quantities a and ,;. If this explanation be the true one we might expect the work of different observers to exhibit the phenomenon in question in different degrees. Taking the mean values of the J's of the class and ,J, which pertain to observers K, H., and T., during the first nine months of 1S67, we find that H. ForH J= 0.106 For N J = 0.063 For T J = - 0.0"..-. Itegarding the irregular differences between the products of a and b by their coefficients in the equations of condition as accidental errors, which we may well do, the differences between the values of J indicate similar differences between the values of the diurnal inequality given by the work of the several observers. That is to say, the mean value of and ,5 given by the work of H. is five- hundredths of a second greater than that given by the work of T. The principal difficulty in the reception of this explanation arises from the circumstance that no such inequality is exhibited in the observations of 1866. For the difference I can give no reason except this: that a much greater number of observations of miscellaneous stars were imposed upon the observers during the nights of ISiiT. Although this would increase the effect referred to, the actual increase is much greater than could have been anticipated as the result of that cause. It is also worthy of remark, that had no correction been applied to J for diurnal change of collimation, there would have been no great discrepancy between the values of-/ and ,; resulting from the two years' work. Supposing the quantities and ,'; to remain constant throughout each year, neither their mag iiitudes nor the causes whence they originate will affect the quantities a and l>, on which depend 20 POSITIONS OF FUNDAMENTAL STARS. the systematic corrections to the .adopted star positions. But, if we suppose them irregularly varia- ble between wide limits, or subject to a regular annual variation, we may satisfy all the preceding equations of condition by zero values of a and 6, each equation giving a separate value of a, ,?, or f. Whether there is any reason to suppose them so variable is a question for the judgment of the indi- vidual astronomer. The present discussion will be continued on the supposition that they are not so variable, and that the corrections indicated by a and b are real. Deeming it desirable to see what systematic corrections would be given by the observations of 1868, their results have also been investigated on the supposition that the correction would be of the form with the result, sin ( 15 1 '), ft = O s .024. If we give half weight to this result, owing to the small number of determinations on which it depends, the definitive systematic correction to the adopted right ascensions will be O s .036sin( lo 1 '), indicating an error of O s .07 in the difference of right ascensions between stars in I) 1 ' and in 21 1 '. CORRECTIONS TO THE POSITION OF THE EQUINOX, AND TO THE OBLIQUITY OF THE ECLIPTIC. The mean corrections to the positions of the sun derived from Hanson's Tables, and given in the American Ephemeris, are as follows. J , Jp, and Jj/ represent the corrections to the right ascension, north polar distance, and ecliptic polar distance, respectively : 1866. 1867. Aa Ay A/ Aa Aj> Ap> 8. 0.08 + 1.3 14 + 1.1 8. + 0.05 + 0.1 II + 0.2 February March - 0. 04 0. 05 + 0.7 0.2 + 0.5 - 0.5 + 0.06 0.00 + 0.6 + 1.2 + 0.9 + 1.2 0.01 + 0.8 + 0.7 0.02 + 0.8 + 0.7 May. 0.00 + 0.2 + 0.2 - 0.01 + 1.5 + 1.5 June + 0.01 + 0.6 + 0.0 + 0.03 + 0.4 + 0.4 July .- 0.01 + 0.4 + 0.4 + 0.03 + 0.7 MH> + 0.02 + 0.7 + 0.6 + 0.02 + 0.8 + 0.7 September October 0.01 -f 0.03 + 1.4 + 1.3 + 1.5 + 1.1 + 0.05 + 0.03 + 1.5 + 0.9 + 1.2 + 0.7 November December -f 0.07 + 0.04 + 1.1 + 0.2 + 0.9 + 0.2 + 0.06 + 0.09 + 1.0 + 1.6 + 0.8 + 1.5 Put z for the constant error in the measures of polar distance ; J u> for the correction to Hanson's obliquity of the ecliptic ; ' A e for the error of polar distance of the ecliptic at the vernal equinox. Then each value of J j>' will give an equation of the form = c J m sin 7 J e cos /. POSITIONS OF FUNDAMENTAL STARS. 21 The equations tor cadi \ear. \\hen solved ly least squares, will become, with sufficient approxima- tion, \->z l'J,,<: (5 Je r= - J p 1 cos /: and the constant correction to the right ascensions of stars will be J = cosec M J e = 2.5 J c. The solution for each year gives 1866. iaer. ^ + 0".G2 + 0".S8 J u> + 0".08 + 0".03 J c + 0".-li' 0".02 j + s .07 s .00 The great divergence iu the value of J for the two years renders the result somewhat uncer- tain. Considering, however, that the divergence may arise from some cause acting iu opposite directions in the two positions of the instrument, and that the preceding four years' observations with the old instruments (lS(52-'(i")) indicate a correction of + O s .05, the correction + O s .03 for the position of the equinox will be admitted. The entire systematic correction to the fundamental catalogue is, therefore, + O s .0.'i + O s .0:5(i sin ( 15 h ) COMl'AIJISON OF RIGHT ASCENSIONS OBSERVED DIRECTLY AND BY REFLECTION. Each annual volume contains a comparison of the direct and reflex observations of north polar distance, but none of the right ascensions. As a comparison of the latter will decide with consid- erable probability whether the meridian to which the observations are reduced is really a vertical great circle, the results of one are here presented. The individual discordances in the case of the several stars may be seen at a glance by reference to the means given under the head " Corrections to the positions of stars in the American Ephemeris." These means were collected in groups, each included in a zone extending through 10 of polar distance. Each discordance was multiplied by sin X. 1'. J)., and the mean by weights taken, with the following results : 1866. 1867. Limits of N. P. D. \li.-m f~D 1?^ win ti jHr.ul ^U ^ Kf Hill 2' (D E)8inj> wt. (D R)slnj> Wt. o o a. i. i. 32 + 0.004 19 - 0. Oil 19 - 0.004 + 210 0.009 9 0.002 20 0.004 11 20 + 0.003 28 + 0.004 29 + 0.004 21 30 + 0.017 .'- + 0.032 15 + 0.022 31 .|.-> 0.028 19 0.000 18 - 0.014 .Vi ClI - 0. 013 28 - 0.034 25 0.023 70 79 0.009 40 - 0.010 39 O.IMI 1 .! 80 89 0.007 28 0.019 37 0. 014 fl> 99 o.u:;- 31 0.028 24 0.034 99 in:. - 0. 04.1 + 0. 010 12 0.008 22 POSITIONS OF FUNDAMENTAL STARS. The general result may be summed up as follows : In the north there is a substantial agreement between the transits observed directly and those observed by reflection. In the south the latter exceed the former by the quantity 8 .018. If the systematic discordance depended entirely on the instrument, the algebraic sum of the south discordance in one position of the instrument, and of the corresponding north discordance in the reverse position, ought to vanish. They do not so vanish. If, in recording a transit by reflec- tion, the observer should, from his less easy posture, or from any other cause, let a swift-moving star slip by a little, the result would be of the same character with that actually found. The above comparison seems to me to indicate, with great probability, that the axis of motion of the instrument is subject to no wabbling amounting to as much as O s .02. CORRECTIONS TO THE RIGHT ASCENSIONS OF STANDARD STARS DERIVED FROM OBSERVATIONS WITH THE TRANSIT INSTRUMENT AND WITH THE TRANSIT CIRCLE. The results given in the following table are all in the form of corrections to the American Ephemeris for the years 1865-'C9 ; the positions for previous years being found by carrying back those found in the American Ephemeris for 1809, with the proper motions there employed. The second column gives the mean correction deduced from the observations with the transit instrument during the four years 1862-'G5, without correction. These are in fact, the standard corrections employed in deducing the clock corrections for the transit circle. The small figures in this and the third column following indicate the number of observations on which the result depends. Next we have the amount of the systematic correction + <)*.<).'? + N .03G sin (a 15' 1 ) deduced from the observations with the transit circle. The sum of these two columns gives the final cor- rection resulting from the observations with the transit instrument, found in the next column. Column "Eesult of circle" gives the mean -corrections resulting from the observations with the Transit Circle during the years 186G-'67. This column is deduced from the corrections to the right ascensions found in the published volumes for those years, the constant correction, + O s .03, being applied to the result. Column C T gives the excess of the transit circle result over that of the transit instru- ment, to which we shall recur presently. The next column gives the correction concluded from the work of both instruments. It is formed by giving to each result a weight proportional to the number of observations. POSITIONS OF FUNDAMENTAL STARS. KXimtiT OF roi;i;i:(TioNs TO THE KICHT ASCENSIONS or M \M.\I;I> STAKS. 23 8Ur. Transit l-i-.-.'-V,:,. Sy-li-matii- ColTl-ctillll. I.V.-nlt of transit. KV^nlt of rilrlr. C T. CnnrliiiliMl correction. H, H. .s. a. t. . n Andromeda' 4- . 002,4 f .OH f .057 4- .037 - .020 f .050 ; IVnasi . . . - .017,. -f . 054 \- .037 h .031,., - .003 4- . 035 ii Cas.-io|ir:r . - .08, -f- .051 - .03 .00,0 f .03 .01 ,< (Vti .... -1- .o:;i... + .051 f .089 f .082 41 .000 f .o,-*> 21 ('assio]>i'a- . - - 4- .09,:, 4- .09 I'isrilllll . - .05-' -)- .049 . 003 - .002,., 4- .001 .1111:1 6 Ceti .... 4- .001 61 + .nlii f . 047 4- .061,, f .014 4- .050 A Cassioi>f;r . . . . . . V Piscimu . . . -f JM- + .044 4- .092 4- ."H6 f .024 4- . 103 a Piscitim . . . - .039 M 4- .04:! 4- . .004 4- .002*, - .002 4- .003 f} Arietis . 4- .OO&j, 4- .041 4- . 047 4- .043 18 - .004 4- . 045 ."ill ('a>Mi>|>r;i> . . 4- .04,,, .04 a Arietis . + . + .O:H 4- . 044 4- .032K - ."012 4- .038 P (Vti .... + .o::i + .oils 4- .069 4- .070,, 4- .007 4- .072 t Cassio],i-;<. . . - - -. 4- -268 + .26 y Ceti .... .11117 + .034 4- . 027 4- .03*.,, 4- .oil 4- .032 a Ceti .... 4- .01-:, + .o:!l + .049 4- .052^ 4- .003 4- .050 48 (H)CViilii . . . . 4- .12u . 4- .12 f Arietis . . . - .027,,, + .029 4- ."002 - .014 14 .016 .007 a Pereei . . . - .052,o + .d->f . 024 4- -09,, 4- .11 4- .04 il Tanri 4- .0054, + .1^5 4- .030 4- .04*., 4- .018 4- .036 f Pereei . . (HK>3 + .oi:t 4- .023 4- .022 r , .(Mil 4- .022 y Eridani . . . + .o:u.. + .022 4- . 053 4- .095,, 4- .042 4- .06* y Tauri . . . + "- + . 019 4- . 042 4- .034.:,, .008 4- . o:w e Tauri . . 4- -004*, 4- .018 4- . 022 4- .014,, .()() 4- .019 a Tauri 4- .(Mil., + .017 4- .018 4- .(MHi M .012 4- .014 i: (':lllli>liip;ir
  • Geminor .040, .004 .044 - .056, .012 .050 3 Ursa* Miuoris . . p Argus .085, .005 .030 - .032,, .002 . 032 e Hydra? . . . .(KM* .006 .010 - .012., .002 .011 t Urea? Majoris . - - - - - o 3 Ursa; Majoris . .01,:, . .01 K Caiu-ri . 4- .'oo-j,. .'ON .004 + .048,, 4- .052 4- .019 1 (H) Dracouis . . . . .17,, . .17 a Hydne . - .001 .006 .007 4- .005,, 4- .012 .000 d Ursa: Majoris - - - 6 Ursa! Majoris . 4- .If.' .006 4- .01 4- .07., 4- .06 4- .04 e Leonis . .01:! . .006 .019 - .0303T, .011 - . 025 /i Leonig . . + .045, . 005 4- .OKI 4- .073,., 4- .033 4- .051 a Li-onis - .004* .III 15 .009 - .022 6 , .013 .015 32 l"r.-a- Majoris . In the case of a Caiiis Miuoris the correction i ;.03G ban been applied to C T on account of the inequality of proper motion given by Anwcrs. 2-1. POSITIONS OF FUNDAMENTAL STARS. EXHIBIT OF CORRECTIONS TO THE RIGHT ASCENSIONS OF STANDARD STARS Continued. Star. Transit 1862-'65. Systematic correction. liV.sillt Of transit. Result of circle. C T. Concluded correction. 8. s. w. *. e. H, y Leouis . . . 4 .017 6 , .004 -f . 013 4 -017 :H 4 .004 4 .014 9 (11) Draconis . . . .08, . .08 p Leonis . - .036,8 .003 - .039 - .034,4 4 .005 .037 t Leonis . 4 .07335 .003 -)- .070 4 .081*, 4 .oil 4 .074 a Urea; Majoris . h .001*4 .002 - .001 4 -OS,, 4 .03 4 .01 i! Leonis . .02055 .001 - . 021 - .08844 .017 .028 (i Crateris . 4 .005,0 + . 005 4 .004,,; - .001 4 . 005 T Leonis . h .007 13 + .001 H- . oiw 4 -015,5 4 .007 4 .012 A Draconis . . . . . 4 .19l9 . .19 v Leonis . . . - .012 37 + .002 .010 .005,9 4- .005 .008 3 Leonis . H- -Oil,* 4 .002 + .013 4 -019.50 4 .006 4 .015 y Ursse Majoris . h .039,! + .003 + .04 4 .07,,-, h .03 4 .07 o Virginia . - .061 3 i + .005 .056 .034,0 h .022 .047 4 (H) Draconis . . .06,, . ;/ Virginis . . . - .01138 4 .006 ."005 4 .019 3 , 4 .024 4 .'006 /? Corvi ... . + .064*-, 4 .008 + .072 4 .100* 4 .028 4 .087 K .Draconis 4 -02 6 . 4 .02 32- Camelopardi . . 4 -50 . .50 a CanumVenat. . 4 .011.2, + .010 + .021 4 -03049 4 .009 4 .(127 Virginis - - .031s, + .012 .019 4 -006,0 4 .025 .013 a Virginis - + .006,00 4 .014 + .020 4 -007V, .013 4 .015 f Virgiuis . 4 .004 6 , + .016 + .020 4 -04143 4 .021 4 .029 t/ Ursse Majoris . .094 4 .02 .07 4 -02,0 4 .09 .00 71 Bootis - .030 M + .019 .011 .023*,- .012 .017 a Dracouis . . - - 4 -03 ;3 - - 4 .03 a Bootis . + .013,.,, + . 023 + .036 4 .033, B .003 4 . 035 Bootis - + . 043 5 + .024 -)- .067 4 .H9ia 4 .052 4 .082 5 Ursse Miuoris . . . 4 -13,3 . 4 .13 e Bootis . . . .018, 4 .026 + ."008 4 -Oils, 4 .003 4 .009 a- Libra; .021;,.. -r- .027 + .006 4 .040 M 4 .034 4 .016 j3 Ursse Miuoris . - .OU4 + .03. + .02 4 -03, : , 4 .01 4 .02 ft Bootis . . . _ . . - .06,, .06 ;3 Libra? .010,,; 4 .031 + . 021 4 .052% 4 .031 4 .031 ft Bootis . . . - .004,, 4 .032 + .028 4 .012,, .016 4 .018 }- Ursje Miuoris . .07,, - - .07 a Coronie Boreal is . 000,,, + .034 + .034 4 .021 .013 4 .028 Serpeutis . ooo w 4 .035 + .035 4 .069 47 4 .034 4 .051 c Serpentis . . .011,,, 4 .036 + . 025 4 -025i9 .000 4 .025 f Ursa? Minoris . 4 -15,3 .15 & Scorpii . . . + .004" ra + "038 + ."042 4 .040,, ."002 4 .041 /3 1 Scorpii . 4 .054,, .039 4- .093 4 -106,., 4 .013 .101 6 Ophiuchi . . + .017,0 + .040 4 .057 4 .049,7 .008 4 .052 T Herculis. . . 4 -21.8 . .21 a Scorpii . . . ."021 4 . 042 4 .021 4 .020,, .001 4 .021 11 Draconis . . .47, + .04 .43 -'.774 - .34 .60 A Dracouis . .01 7 .01 f Ophinchi . - .050,4 + . 043 .007 4 .018,, 4 .025 4 .005 ij Herculis. . . 4 -04,8 .04 K Ophiuchi . - + .0283,1 4 .047 4 ."070 4 .067,, ."003 4 .069 (I Herculis 10 Ursse Miuoris . .08,, .08 a Herculis. + ."OOI M 4 . 049 4 .050 4 -0464, .004 4 .049 6 Ophiuchi .002 4. .050 4 .048 4 .071,, 4 .023 4 . 057 a Ophiuchi + -012 85 .051 4 .063 4 .06153 .002 .062 u Draconis . . . . . . . 4 .06,0 - - 4 .06 fi Herculis. .007 W + .052 4 .045 4 .023., .022 4 .034 4 l Draconis . . _ . .05 5 .05 y Draconis . . + .05, 4 .05 4 .10 . 05,, ."l5" .III! y* Sagittarii . . /t 1 Sagittarii . .029 18 .023s, .054 4 .055 4 .025 4 .032 4 -077 7 4 .057,, 4 .052 4 .025 4 .040 4 . 035 6 Ursse Minoris . , . . r/ Serpeutis . - + ."011,3 4 .056 4 .'067 4 .H*. 4 .045 4 .085 1 Aquilse . . . + .033 7 4 4 .058 4 .091 4 -122.7 4 .031 4 .097 a Lyrse. . . . + .OOlse + .058 4 .059 4 .044,, .015 4 -051 /} Lyra. . . . + .01545 + .060 4 .075 4 .031,0 .044 4 .061 POSITIONS OF FUNDAMENTAL STARS. INHIBIT OK roi;i;i:rnoNs TO Tin: I;K;IIT ASCKNSIONS OF STANDARD STARS Contiim.-.i. Star. Traii-it Systematic correction. Result of transit. Result of circle. C T. Concluded correction. . ft ft ft t. i. r. Sajjittarii . .024s, 4- .060 4- .036 4- 035 1:! - .001 4- . O3t; .">o Draeoni.f _ . i tyt , 4~ . ** i 04't 4- .061 4- . 104 111 4- .007 . 11 Hi ' Cephei . 4- .25,o 4- .06 4- .31 4- -IS, 4- .16 4- -24 u Piscinm . .016*, 4- .056 4- .040 4- .031,, .009 4- . o:t7 26 POSITIONS OF FUNDAMENTAL STARS. The column G T is that which principally commands our attention. The first feature to be noticed is the magnitude of the discrepancies. Taking their mean value, without regard to sign, for the 109 clock stars observed by both instruments, we find it to amount to 0".017. This is a greater mean difference than we should expect to arise from the purely accidental errors of obser- vation. Let us see how. far it is of a systematic character, depending either upon the right ascen- sion, the polar distance, or the magnitude of the star. Dividing the circle of E. A. into eight parts, we find the following mean value of C T for the clock stars of each octant : Octant. C T 1 8. + 0.002 2 + 0.007 3 - 0.006 4 + 0.008 5 + 0.012 6 + 0.007 7 + 0.010 8 0.010 We see that the circle results are, on the average, greater by O s .004. After correction for this difference, the results will indicate a cyclical difference, of which the largest term is O s .005 cos , but they are not regular enough to predicate anything certain upon. It will be remembered that no corrections for cyclical error have been applied to the circle results, and the somewhat unex- pected result of this comparison is that they do not seem to need any such correction. Arranging the values of C T according to polar distance, and taking the mean for each ten degrees, we have the following mean values of this quantity. For stars less than 50 from the pole, the mean by weights proportional to the number of observations has been taken. For the other stars the mean is taken indiscriminately. Limits of N. P. D. C T o o 8. 10 20 + 0.05 20 30 0.03 30 40 + 0.01 40 50 + 0.02 50 CO 0. 005 GO 70 0.006 70 80 0. 006 80 90 0. 001 90 100 + 0.016 100 110 + 0.017 110 120 + 0.015 North of the zenith (polar distance 51) the differences fall within the unavoidable errors of the few observations made with the transit. But south of the zenith we find the difference to assume a well-marked systematic character, the positions given by the circle being uniformly less north of the equator and greater south of it by amounts too great to be the result of accidental errors. Such a result would follow from a constant error in the collimation of either instrument. Me- ridian transits are referred to a supposed great circle passing through the pole, and coinciding with POSITIONS OP FUNDAMENTAL STARS. 27 tin 1 true meridian of reference on the circle of mean declination of clock stars. If this supposed great circle is really a small one.it will cross the meridian of reference on the circle of mean declina- tion. To express the fact in algebraic form it is easy to see that an error of J c in the collimalion will, by its direct ell'ect and by the resulting errors in the polar a/.imuth and the clock correction, give rise to the error J c (tan << sec tan 3 + sec and sec ii for the stars on which the clock correction depends. If we suppose OpbincM 4- 0.023 a 1 .1-1 in is . o.in:: ' AqlliliU . + 0.042 a Virninis 0. 013 T Aquilitt . 0.000 I!(K)tiM . 0.003 // Aquarii . + o. o:; ii Scnrpii . 0. 001 f Aqiuirii . (1. (HIS a Lynn 0. 015 ft Capricorni + 0. 022 a Aqililin . 0.006 JT Aquarii . 0. 014 a PiscisAus. + O.u: 1 .- Mean . . . 0. 004 Mean . . . + 0.014 The difference of the means, 8 .018, is more than three times the probable mean difference of two sets of values of T, selected at random from the list. It is, therefore, highly probable that there is a real difference depending on the magnitude of the star, the faint stars being observed the later with the circle. Such a result is not an improbable one. The spider lines of the circle appear much finer than those of the transit, while the illumination of the field is fainter. The effect of the latter cause will probably be to make an observer later in recording a transit. If all stars were recorded later by the same amount, their right ascensions would not be affected. But the stray light which surrounds a bright star forms a bright ground for the dark transit wire a perceptible time before the star reaches the wire, and thus tin- approach of the two objects is distinctly seen. As we take fainter stars the stray light disappears, and the approach is less distinctly seen. Thus, tin- elfect in ipicstion will be exaggerated as the star grows fainter. . Whatever be the cause of this etfeet, \\e ha\e abundant evidence that the right ascensions of 28 POSITIONS OF FUNDAMENTAL STARS. faint objects given by different authorities sometimes exhibit discrepancies which can hardly depend on anything but the magnitude. A striking instance of this is given by the planet Neptune. In the Washington Observations for 1806, p. 400, is given a column of corrections to the Ephemeris of Neptune, found in the appendix to the American Ephemeris for 18(59, from which it appears that the mean correction to that ephemeris given by the observations with the transit circle is + N .09U. But a similar comparison with the Greenwich observations for 18(5(! indicates no correction what- ever. In 18(57 a brighter illumination was given the Held of the Washington, circle, and the dis- crepancy was reduced to O s .03(). These circumstances strengthen the view already presented that an observer may observe transits at night systematically later than in the day. EIGHT ASCENSIONS OF POLARIS. The right ascensions of Polaris demand a separate investigation, on account of the different character of the data on which they depend, and the existence of well-marked personal differences in the results. In the following collection of right ascensions all results are omitted except those of consecu- tive transits by the saifie observer. As a single transit gives only an equation of condition between the azimuth and the right ascension, a pair of opposite transits is considered as giving only a single, result for right ascension. As the coefficients of the azimuth in the equations are nearly equal, and of opposite signs, we may take as this single result the mean of the separate results of the two tran- sits reduced with any value of the azimuth reasonably near the truth. Classifying the right ascensions according to the observer, we have the corrections to the right ascensions of the American Ephemeris given on the next page. The third column gives the correc- tions as they result immediately from the observations. Large personal differences in the results being evident, the mean result from the work of each observer during each year is taken and is given at the end of the columns. It appears from this that there is a difference of more than, two seconds between the result of Professor Hall's observations and that of Mr. Thirion's. Eeduced to arc of a great circle, this difference amounts to 0".82, or 8 .054 in time. It will also be seen that each of the three observers who observed throughout both years gives a smaller correction in 1867 than in 18C6, the differences being as follows: This change may be partly due to the different position of the instrument during the second year. For the purpose of reducing the results to a common standard, the general mean is taken, and found to be appreciably + 1 8 .0. The systematic correction to reduce the results of each observer to this standard is applied to the results in the third column to obtain those in the fourth. It may be a question whether this correction should be considered the same for both years, or whether the results for each year should be taken and applied separately. A middle course has been adopted by applying the following corrections : 01 is. 18>. 18G7. 8. X. N. 0.0 + 0.4 II. + 1.0 + 1.0 i;. 0.1 T. 1.4 -1.1 POSITIONS OF FUNDAMKNTAL STARS. 29 Thus, the fourth column Drives the results as they would have been had all the observations made b\ a single mean observer. KllIlIT ASCMNSIONS or PHI. \1!1S HKIHVKn KUdM DOriH.K TRANSITS ]!V T1IK SKVKIi.U, OI'.SKKVI- I;S. _ Cc.rriTt n In Am. K|ilirm. j[ = - ti Corrcct'n If. Am. Ephcin. ji Date. O Correct'n to Am. Eiilicin. Reduced cor- rection. Date. Observer. Correct'n to Am. Ephem. If 1866. 1. ,. 1866. ,. . 1867. .. s. 1867. I. #. .h.u. 4 R. + 2.0 + 1.9 July 11 T. + 14 ao Jau. 7 K. 1.2 0.8 Sept. IB N. + 0.6 + 1.0 5 11. + 1-4 + 2.4 13 H. 0.0 + 1.0 11 H. + 0.4 + 1.4 23 11. 0.0 + 1.0 8 H. 2.5 1.5 14 T. + 1.4 o.o 17 X. + 0.8 + 1.2 24 T. + 1.7 + 0.6 9 R. + 0.3 + a 2 26 X. + 0.8 + 0.8 23 T. + 0.3 0.8 27 H. + 1.3 -( 2.3 Feb. 1 R. 0.1 0.2 August 3 T. + 0.6 - 0.8 84 X. 0.5 0.1 28 T. + 4.4 + 3.3 3 T. + 2.3 + 0.9 4 R. + 1-7 + 1-6 28 X. 0.0 + 0.4 30 X. + 2.5 + 2.9 :, R. + 1.0 + 0.9 r, N. + 1.2 + 1.2 29 H. 0.0 + 1.0 Oct. 1 H. 0.8 + 0.2 6 H. 0.4 + 0.6 9 R. + 1.6 + 1.5 31 N. + 2.4 + 3.8 7 X. 0.0 + 0.4 15 R. 2.7 2.8 10 H. 0.4 + 0.6 Feb. 5 H. 1.2 0.2 8 H. 0.4 + 0.6 16 H. 0.0 + 1.0 15 T. + 1.6 + 0.8 6 T. + 2.5 + 1.4 12 T. + 3.1 + 1.0 20 R. 2.2 2.3 16 R. 0.1 -0.2 7 N. 0.7 0.3 14 H. + 1.5 + 2.5 Jl T. + 3.4 + 2.0 17 H. 0.8 + 0.2 26 H. -1.7 0.7 15 A. + 1.5 22 R. 1.0 1.1 1- T. + 4.0 + 3.6 27 T. + 0.4 0.7 16 T. + 2.5 + 1.4 March 5 II. 0.4 + 0.6 22 T. + 3.4 + 8.0 March 18 N. + 1.5 + 1.9 18 A. + 1.7 8 X. r 1.2 + 1.2 Sept. 5 T. + 3.2 + 1.8 28 N. + 0.5 + 0. 9 19 T. + 2.0 + 0.9 10 T. + 3.7 + 2.3 8 T. 1.0 2.4 29 H. -0.6 + 0.4 23 H. 2.2 1.2 26 X. 1.2 1.2 12 T. + 0.7 -0.7 30 T. + 2.7 + 1.6 24 A. + 0.4 . 27 R. + 2.0 + 1.9 14 T. + 1.0 0.4 April 1 X. 0.6 0.2 M 6. 1.2 0.2 30 N. 0.9 0.9 15 R. f 2.0 + 1.9 2 H. 1.1 - 0,1 Xov. 5 A. + 0.3 April 5 R. + 0.8 + 0.7 17 T. + 1.8 + 0.4 3 T. + 2.2 + 1.1 6 T. + 2.4 +- 1.3 11 T. + 3.3 + 1.9 22 N. + 2.2 + 2.2 5 H. 0.8 + .0.2 8 A. + 2.2 1!' X. + 1.4 + 1.4 27 K. + 2.6 1 2.6 6 T. + 8.2 + LI 12 A. \- 0.1 20 R. + 0.4 + 0.3 28 R. + 0.8 + 0.7 13 T. (- 1. 4:) ( 2.5) 18 H, 0.1 + 0.9 May 3 R. + 1.3 + 1.2 Oct. 4 R. + 2.4 + 2.3 17 T. + 1.8 + 0.7 19 A. + 1.6 . 4 H. 0.8 + 0.2 5 H. + 0.6 + 0.4 18 H. + 1.0 + 2.0 20 T. + 0.4 0.7 5 7 14 15 19 21 T. X. N. R. T. N. + 1.7 + 0.3 0.2 + 1.8 + 2.2 + 0.8 2.0 6 8 15 16 17 18 X. X. X. R. H. R. + 1.2 + 3.3 + M + 3.0 + 1.3 + 8.0 + 1.2 + 3.3 + M + 8.3 + 1.9 96 May 9 11 14 17 18 H. N. T. T. H. T. + 2.9 + 1.2 + 3.7 + 0.1 0.4 + 1-2 + 3.9 + 1.6 + 2.6 1.0 + 0.6 + 0.1 Dec. 9 Mean. . H. N. H. T. A. + 1.3 + 2.3 + 1.8 + 2.3 + 2.2 2.0 + 0.39 0.10 + 2.00 + 1. 11 22 H. 0.1 + 0.9 19 H. + 1.0 + 3.0 23 N. + 0.1 + 0.5 23 T. + 3.6 + 2.2 20 X. + 2.6 + 2.6 24 H. 0.0 + 1.0 24 N. + 1-1 + 1.1 23 R. + 1.4 + 1.3 27 N. 0.8 0.4 H. + 1.0 + 2.0 27 X. + 2.2 + 2.2 31 H. + 0.4 + 1-4 X. + 0.1 + 0.1 31 H. 0.2 + 0.8 June 1 N. + 0.6 + 1.0 30 T. + 5.0 + 3.6 Xov. 1 R. Kl + 0.4 4 T. + 2.8 + 1-7 31 N. + 8.4 + 2.4 2 II. 0.9 + 0.1 6 X. + 0.7 + 1.1 June 4 X. + 1.6 + 1.6 5 X. + 3.4 + 3.4 10 N. + 1.2 + 1.6 6 II. + 1.2 + 2.2 6 R. + 2.3 + 8.9 11 T. + 2.6 + 1.5 7 X. 0.2 0.2 7 T. + 5.6 + 4.2 15 T. + 0.8 0.3 11 N. + 1.8 + L8 8 R. 0.8 0.9 21 H. 0.8 + 0.2 13 JI. + 1.8 + 3.8 9 H. + 1-2 + 2.2 July 24 T. + 2.4 + 1.3 15 H. 0.3 + 0.7 12 X. + 4.1 + 4.1 27 T. + 2.0 + 0.9 n R. + 0.6 + 0.5 13 R. + 3.8 + 17 31 T. + 2.0 + 0.9 20 T. + 3.8 + 1.8 R. + 4.2 + 4.1 Ang. 23 H. 1.4 0.4 SI X. + 1.0 + 1.0 21 T. + 3.1 I- 0.7 Sept. 4 T. + 2.7 + 1.6 '-T. N. + 1.0 + 1.0 M T. + 8.8 1 1.4 5 H. + 0.6 + 1.6 2fi 30 .Inly 5 6 7 R. H. X. R. H- f 2.0 0.0 0.3 + 1.4 + 0.4 + 1.9 1.0 0,3 i.:i + 1.4 Mora. - X. X. II. R. T. -0.4 -0.4 6 n 12 13 18 X. T. X. II. T. + 0.5 + 1.5 1.0 M + 2.7 + 0.9 + 0.4 0.6 + 1.9 + 1.6 + 1.18 + 0.14 + 1.13 + 9.48 POSITIONS OF FUNDAMENTAL STARS. The principal object of this fourth column is to furnish the means of detecting any diurnal change in the pointing of the instrument near the pole. The old transit instrument is known to be affected with such a change.* The existence of this state of things will be manifested by a corre- sponding inequality in the time of transit of Polaris, depending upon the time of d ; iy at which the transit takes place ; there will, therefore, be a corresponding annual inequality in the right ascen- sions of this star deduced from observations. Let us put n for the error of pointing of the instru- ment near the pole, a west azimuth being considered positive. Put, also, w,, and for the values of n at upper and lower transits, respectively ; then the upper transit will be too late by n u sec <5; and the lower transit by n a sec S. The right ascension, deduced from the transits, will therefore be too late by i (n u n*) sec S. If the pointing of the instrument undergoes a periodic diurnal change, we shall have n a sin D + b cos D, a and b being constants, and D being the time of day expressed in arc. Put D u for the time of day at which upper transit takes place ; the lower transit will then take place at D u + ll" 1 , and we shall have M U = a sin D u + b cos D u ; n a = a sin D n b cos D u ; and the error of right ascension will be da = (a sin D u + b cos D u ) sec <5. About April 7 of each year the upper transit takes place at noon, and we then have D u = and we have at any time thereafter D n = y, y being the fraction of a year counted from April 7, and expressed in arc. Sec S being about 40.7, we have 8 a = 40.7 ( a sin y + b cos y). We shall consider the fourth column of the preceding table as giving a series of values of 3 a plus an unknown constant, extending through a period of two years. Combining the correspond- ing months, and taking the mean value of 3 a + c for each month, we have, with the omission of December Month. Mean and equation of condition. No. of obs. Wt. January- s. + 0. 68 = c + 0. 99 X 40. 7 a + 0. 14 X 40. 7 b 12 1 February . 0. 11 = c + 0. 79 +0. 62 14 1 March + 0. 87 = c + 0. 37 +0. 93 10 1 April '+ 1. 08 = o 0. 14 + 0. 99 12 1 May - . . + 0. 96 = c 0. G2 + 0. 79 24 2 June . + 0. 19 = c 0. 93 + 0. 37 19 2 July . -f 0. 73 = c 0. 99 0. 14 10 1 August - + 0. 77 = c 0. 79 0. 62 11 1 September . + 1.12 = c 0.37 0.93 22 2 October.. . + 1.35 = c + 0.14 0.99 22 2 November . + 1.70 = + 0.62 0.79 17 2 Washington Observations for 1862, pp. xv. x\ i. POSITIONS OF FUNDAMENTAL STARS. 31 The solution of those equations gives 40.7 a = -= E O : Z' O E'. POSITIONS OF FUNDAMENTAL STARS. 35 "We then have These values of (E) and (E') will be the same as if they were measured from a visible pole in the heavens, corresponding to the mean of the stars by which the value of

    = 61 6 21.20 ; 6 21.20. These quantities being applied to the measured values of E O = Z and O E' = Z', values of the reduced polar distances of the stars were thus obtained. Let us represent these assumed values of y and ?' by p and f' , the true values not being known. Let us also put 3y and H' could be deter- mined independently. As they cannot be so extended, we have to employ the auxiliary i in the expressions y = i(Z +Z,); /, <<> p' = 180 2i. Since ?' is used only to fix the position of the reflected pole, the value of i to be employed should be derived solely from those stars which may be observed on both sides of the pole. Actually it has been derived from the reflection observations north of the zenith, which leads to nearly the same result. The values of i employed are, therefore, for 1866, i = + 0".!)(i 1867, i = + 0".45 The further investigation of y is substantially the same with that for the correction of latitude POSITIONS OF FUNDAMENTAL STARS. already {riven, with the differenee thai i has been applied to the provisional polar distances in advance. The results are as follows: Had the pole been a visible point in the heavens, the pointing on which corresponded to the mean pointing on cm-unipolar stars above and below the pole, we should have found for the measured arc, from that point to the adopted zenith point derived from collimator observations, o ' " " in 1866,

    ' to the observed zenith distances, we shall obtain the results already set forth, that the polar distances north of the zenith exhibit no great discordances, whether measured above or below the pole, directly or by reflection, while in arcs which extend south of the zenith, the reflected polar distances are constantly greater by a nearly constant amount. The corrections which have to be applied to the positions obtained by the preliminary reduc- tions to reduce them to actual measures from the pole to the stars are simply, flexure + division + Srai "ni.s 1 0. 4, + 0.40 1 Pegasi .... r 1-7, + 3.3, 1 2. 5, + 2.50 y Dracouis . . . j 0.3, + 1.0, + 0.2, + 0. 1 4 + 0.36 Aqnarii . . . + 0.8 4 0.0, + 0. 4, + 1-5, + 0.66 r' Sagittarii . . . - 0.4, 0.40 Cephei. . . . - 1.2, -0.6, - 0.8, 1.0, 0.91 f Suttittarii . . . + O.G, - 0.6, 0.00 Cephei, S. P. . . + 1.2, + 1.20 1 Serpentis . . . + i.o, 0.0, + 0.40 Aquarii . . . + 1-0, + 0.4, + 0.64 1 Ureas Minoria . -1.26, - 0.37, -1.40, 0.68, 1.09 { Pegasi. . . . + 0.5 4 + i.o, + 0.5, + 0.9, + 0.49 1 UrewMin.,S. P. . + 0.57, . . + 0.99, + 0.81 11 Cephei. . . . - LI, - 1.0 4 - 0.5, 6.86 1 Aqnilo; . . . - 0.7 4 + 0.9, - 0.5, - 1.9, 0.45 i\ Capricorni + 0.0, + 0.4, + 0.57 a Lyrae .... + 0.6, + 1.3, + 0.99 79 Draconis . . . 0.5, - 1.0, 0.75 ff Lyra) .... - 0.3 4 - 0.3, 0.30 79 Draconis, S. P. . + 1.6, + 1.60 * Sacittarii . . . + 1.0, + 1.2. + 1.12 a Aqnarii . . . + 1. 4, + 0.9, + 0.6, + 1.2, + 1.00 50 DraconU . . . - 1-1, - 12, - 1.2, - l.I 1.15 9 Aquarii . . . + 1.4 4 + 1.2, + 0.8, + 0.9, + 1.M g AquilaB . . . + 0.9 4 + 2.2, + 1.0. + 1.4, + 1.15 JT Aquarii . . . - 0.4, + 2.4, + 0.6, + 0.48 i Uraconia . . . 0.8, - 1.1, - 0.7 4 - 0.2, 0.55 1 Aquarii . . . + 0.9 4 + 0.4, + 0.9, + 0.85 T Draconis . . . 0.6 - 0.3, 0.42 g Pegasi. . . . + 1.5. + 0.8, + 1.5, + 1.37 5 Aqnilffl . . . 4- 0. G, + 1.6, 1 0. 9, + 1.3, + 0.97 i Cephei .... - 0.4, + 0.1, - 0.6, - 1.0, 0.46 1C Aquil.r . . . + 0.6, + 0.4, + 0.8, + 0.6, + 0.69 i Cephei, S. P. . . + 1.3, + 1.30 Y AquiliB . . . + 1.5 4 + 3.1, + 1.5, + 1.63 A Aquarii + 0.9, + 1.8, + 0.1 4 + 1.1, + 0.69 a Aquihe f 1.0, + 1.4, + i.o, + 1.19 a Piscis Australia . + 1.3, r 0.6, + 0.81 i Draconis . . . - 1-1, - 1.9, 1.50 a Pegaai .... + 1.8 4 + 2.8, + 2.9, + 2.1, + 3.15 Aquilie . . . + 0. 7, + 1.0, + 0.90 o Cephei .... - 1.6. - 0.8, 1.30 A Une Minoris . + 0.9, + 0.2, - 0.9, + 0. IS o Cephei, S. P. . . + 1.6, + 1.60 A UnuB Min., S.P. . 0.0, - 0.1, 0.05 8 Piscium . . . + 0. 7, + 0.2, + 0.8, 0.0, + 0.28 T Aiplil." . . . + 0.8, + 1.3, + 1.00 t Piscium . . . + 0.5, + 0.4, + 0.5, + 0.45 a 1 Capricorni + 1. 0, - 0.4, + 1. 1. + 1.1, + 0.85 y Cephei .... - 0.9 4 - 0.1, - 0.3, 0.5, 0.53 K Cephei .... - 1.0, 0.9, 0.95 f Cephei, & P. . . 2.7, + 0. 1, 0.37 UK STAKS OF THE AMERICAN F.I'IIFMF.KIS, DEDUCED FROM (HiSFKVATIONS WITH I III: TRANSIT IXSTRTMKXT ANI> THE TRANSIT CIRCLE DURING THE YEARS 1862-'67. SI. II. ij 7 ~ i_ o -i (4 i i 11 | CHIT'II to Am. EphciiL. 1874 J 1 a ri ri j Secular varia- tion. i ii 41 ii k. m. t. >. t. 1. t. O I It // // // Xlnll.'lit. .].. . 119 1 40.344 -i 3.0773 + . 0182 + .0102 + .050 16 61 37 39. 10 20.054 + 0.011 t- 0.146 + 1.96 ) IVlMM . . n 6 32. 5:i a. OBU .0100 j- .0006 < .035 15 75 32 22. 14 20. 047 + 0.020 (- 0.011 + 1.46 a C:is.Hi,iiN'jt! . 18 33 C.B7 I 3.3559 + .0550 + .0076 .01 11 31 III :tt. ."7 19.845 + 0.088 r 0. 034 0.08 li (Yti .... 90 37 :l rt>3 i 2. W3 . ii:>7 .11113 + .083 13 III- 12 2.65 19. 793 + 0.079 0.020 -)- 0. 93 -'1 * 'llSHiop.-H! . u 37 6. 46 3. SI7I f . 1581 .0114 4- .08 10 15 43 23.07 19.792 + 0.0% | 0.060 1.89 f I'i-t iUlll . . 135 56 11.931 + 3.1130 + .0086 .0035 4- .052 13 8* 48 38. 53 19.455 I- 0. 117 0.000 4- 1.81 Polaris . . . 7 1 11 17. 34 +20.014 + 14.240 + .073 .33 56 1 23 1.47 19. 092 + 0.910 0.006 0.07 H C,.|i . . . n 1 17 31. .V.'l ; 3.0113(1 + .0(117 . IXI.-,3 : . UM 10 98 51 18. 47 18.918 + 0.152 I 0.220 + 1 90 il risciinn . . in 1 24 ::i OH :i. I'.i-i + .0142 . IHHI'.I 1 .IH.C.I 14 75 19 31.71 18. 706 + 0. 175 0.000 + 1.91 " l'i*rium 63 1 3* :u.!ii4 3. i.v.i j .11111 + .0061 + .003 13 81 29 52. 17 18.230 + 0.199 0.009 I- 1. 24 ,1 \ii.ti-. . . . 117 1 47 27. 779 + 3.2841 + . 0182 + .OOC2 + .045 14 69 49 43. 85 17.891 + 0.224 (- 0.109 + 1.81 ."41 ( '.i-sii.|if;i- . 111 i :_ 2:1.111 1. '.i.-iil I-:. .011 + .04 7 18 12 35. 21 17. 692 0.345 0.000 0.43 a Aril-tin . . . M i 59 5o. IKK > :i. 3534 4- .0203 i .II14-J + .038 16 67 9 13.53 17.375 H- 0.253 + O.i:t7 4- 1.35 i' c,-ii .... 4* 2 6 6. 736 i 3. 1733 + .0115 . OtH'J + .072 10 81 45 52.50 17. 095 I 0.248 I- 0.040 + 0.86 t C:iHMiulM-lB . 8 2 18 23. 41 i. -u + .1300 .008 + .86 7 23 11 a 46 16.508 H- 0.404 + 0.020 0.74 ) Ci-ti . 44 2 36 34. 016 : 3. Illl. + .0092 .0094 4- .031 11 87 18 49. 43 15.556 + 0.291 |- 0. 191 -r 1. 18 a (Vti .... 71 2 55 29. 188 r 3. 1300 i- .0097 .0015 + .050 13 86 25 19. 29 14. 459 + 0.321 |- 0. 103 i 0. 42 !: C. pll.'i . . . M 3 3 55. 35 + 7.322 + .350 + .016 + .12 11 12 44 50. 92 13. 9X> + 0.770 + 0.066 0.13 a Arii-tis . . . 24 3 7 25. 951 3. 1:11- 1 + . 0176 .0015 .008 7 69 26 21. 86 13.714 + 0.370 + 0.071 + 1.80 a IVrm-i . . . 24 3 15 a 19 i 4. 245 I + .0483 + .0020 4- .06 10 40 36 14. 58 13.220 + 0.470 + 0.043 0. 30 >I Tauri . . . 68 3 39 45.629 i 3.5525 + .0173 + .0010 + .035 13 66 17 57.30 11.520 + 0.430 4- 0.060 4-0.93 < Pl-Wi . . . 8 3 45 57. 894 i- 3.7551 + .0222 + .0006 + .022 3 58 30 19. 58 11.072 + 0.460 + 0.049 + 2.25 j- Kriihuii 38 3 51 57.948 2. 7! 120 + . 0045 + .0044 + .067 7 103 52 49. 62 10. 630 + 0.350 + 0. 120 i 2. 30 y Tauri . . . 41 12 23. .-71 ; a 3983 + .0116 + .0085 + .038 10 74 41 19.90 9. 074 + 0.447 + 0.031 + 1.71 c Tauri . . . 55 21 1. 674 + 3.4876 + .0122 + .0076 + . 019 10 71 6 37. 91 8.395 4- 0.467 + 0.031 + 1.73 Tauri . . . 151 28 37.806 + a 4311 + .0106 + .0045 t. (Ill 18 73 45 16. 86 7.793 + 0.465 + 0.166 + 1.71 a Cami-liipiinli . 13 41 .-. i:-j + 5.915 + .070 .003 .17 10 23 52 56. 91 6.765 + 0.814 0.009 f 0. 44 t \illit:;r 37 48 31. 808 + 3.8971 i- .0146 .0008 .011 9 57 2 34. 21 6.153 + 0.543 + 0.020 + 1. 6C 11 Ormnis . . . 28 57 a 536 | 3. 4-.MI 4- .0078 (- .0025 .037 8 74 46 46. 94 5. 432 + 0.483 + 0.031 + 1.67 a Aurlgie . . 17 5 7 5.30 f 4.4134 4- .0160 + .0086 .03 3 44 8 15.38 4. 5r -j- 0.630 + 0.420 + 0.40 Orion is . 120 5 8 17. 481 + 2.8808 + . 0040 .0001 + .025 18 98 21 15. 03 4.486 + 0.411 + 0.017 4- 1.13 11 Tiiuri . . . 111 5 18 4. 523 + 3. 7h.V . M t .0017 + .010 17 61 30 19. 51 3.648 + 0.545 I 0.191 4-0.96 <' Idiiinm . . . 78 5 2521.970 3. (MW.I 4- . 0038 t- .0009 .004 9 !K> 23 52.65 3. 019 + 0.443 + 0.040 4. 1.01 a I . |>"ii- . . 15 5 26 59.879 i- 2.IM44 . . IXKIII . (Klil .010 107 55 2.878 + 0.383 0.000 ' Onoiiis . 79 5 29 37. 077 + 3. (Mi! + .0036 .0005 4- .023 11 91 17 14.93 2.651 c 0.441 + 0.011 + 1.23 .1 ('"luniliiB . . 19 5 34 56. 569 + 2. 1709 + .0028 4- .0026 .011 I 124 8 43. 52 2.178 4- 0.316 0.000 + 2.53 a < iiinuis . 144 5 48 H. II7-J +- 3.-J15I + . IKI-JS + .11017 4- .003 18 82 37 11.89 1.038 4- 0. 474 0.000 + l.U li 1 M-niiiiornni . 38 6 15 5.755 -f- 3. i;-;n:i . 0004 + .0059 .007 7 67 25 21. 32 + 1.320 + 0.529 4- 0. 140 4- 1.32 ) lii'tiiinot inn . 13C 6 30 12. 1 l.'i i- 3. Hi 111 .0014 4- .0040 .(in 13 73 --"I 33. 00 4- 2.635 + 0. 501 4- 0.040 4- 1.44 .M c.-pli.-i . . . 47 6 38 43. 17 +30.406 2.011 - .106 4- .17 21 2 45 37. 67 -j- 3.373 + 4.341 0. 003" O.S8 CantaMajoris . 134 6 39 25. 074 f 2. GWIB .0000 . 0364 [- .054] 13 106 32 25.02 4- 3. 371 4- 0.381 f 1.383 4- 2.64 r I 'llllis M;ij..l i> 44 6 53 31.066 j. x,; i 1- . 0013 + .0013 .019 10 118 47 49.74 + 4.638 |- 0.333 + 0.020 + 1. 32 t Citnis Miijori.H . 11 7 :i ii. 3> j. i.i'.i.. f .0012 + .0003 .1111; 3 116 11 18.79 + 5.453 + 0.340 0.009 + 1.67 '' < ii-miii"! urn 53 7 12 21 455 :i. .v.nii . IXIVJ - .0004 .026 13 117 4(1 52. in + 6.227 + 0.496 + 0.020 i 1.H1 0* (iclllill.n Mill 76 7 26 18. 121 3. -.Ml .11131 .IIH'.I i . ->7(l 10 57 49 45. 77 + 7. 374 + 0.527 + 0.076 4-0.97 a Cani> Minmis 167 7 33 29. 718 3. 1III7 .0042 .057 .110 16 84 26 39. 52 + 7.876 + 0.420 [+1.040] + 1.09 & Gfininorum . 149 7 37 21. -500 3. 7-J.HI .ill-.'.'. .11171 .0114 14 111 :I9 44.81 + R262 + 0.480 | 0.060 t 1.41 t ' i.'iiiiimriini . IS 1 45 :w. M:, .11130 _ 1 .050 5 ii-' M 1.95 + 8. 913 + 0.478 + 0.049 + 1.71 l."i Ar^iin . . . 23 ii :,!; '. Mf.t (Mill .0046 . 032 8 113 55 53.08 I 10. 179 4- 0.317 0.060 + 1.83 Hydno . . . 60 8 39 53. 451 :i. I'.KKI .0071 .11117 .012 10 83 6 22.65 + 12.884 I 0.350 + 0.040 + 1.98 i Urai' Mrtji'ii- 1 ! 4 1C70 .0444 . 0453 4 41 26 59.65 + 13. 568 + 0. 436 + 0.280 0.80 ff 1 Ursa? Majoria . 13 8 'S8' 55.' 15 - 1 . 134 . IKK .'of 11 24 20 25. 3 ! .14.114 u tee h 0.097 2. 15 It 1 ':nn-i i . . . J4 11 II 42. 254 3, -ivs _ . INI:I i .OIKIO + .020 7 7." IH 37.92 14. CM 0. 3-.-.I + 0.011 + 1.77 1 DracunU . . 6 9 If 31. l:t U. l(i 3. iui:< .0082 .0006 + .035 12 78 46 4.06 + 18.917 . 0.146 i 0.020 | 1.S4 a I'ruH-Majorm. 41 10 55 41. 04 _ Jl-,-.' . 0195 . 14 -27 32 52. 18 + 19. 270 + 0.145 + 0.086 - 0.41 HIM . 'M 11 7 11.525 -r 3. 1908 .0134 + .0117 - .027 14 68 45 5a05 + 19. 525 II. 1IKI + 0. 140 ! 1. cl A Crati-riH . . 46 11 12 50.585 3.IP037 + .0063 . C078 f .005 9 104 4 31. 88 + 19.632 n. u-.' 0.180 + 1.35 T I.f.tllis . 2r- 11 21 I.'.. 1-Jli 3.0-112 .002J + .0019 + . 012 9 86 25 II M + 19. 769 + 0.068 > 0.020 4- 1.11 A Draronin . . 19 11 2.1 3:1. :,:. 3. i;:,:i .113 .011 + .19 16 1957 6.11 t 19. 803 . 11.1177 + 0.060 1.53 v Leonifl . . . 56 11 30 17. 5!i9 3.1171- + .0002 .0000 - .008 9 90 6 23. 29 + 1!>. 887 + 0.050 0. 031 + 1.59 II Leonis . . . 116 11 42 25.660 T 3. 1001 .0073 .0344 + .015 17 74 42 5.56 + 19. 990 + 0.026 + 0. 103 + 1.B7 y Urea- Mnjoris . 18 11 46 58.98 + 3. 178S .0440 .- .01 in + .07 12 35 34 57. 42 4- 20.023 f 0.019 0. 003 + 0.51 o Virginia . . 51 11 56 35.224 3. 1173.', .00:12 .0130 1+ .006 10 80 32 42. 33 + 20.055 0.005 0.020 + 1.48 4 Dnu-mim . . 18 12 6 4.78 - 2.900 . 1-JH - .010 '- .06 16 11 39 411 15 + 20. H48 0.019 + 0.008 _ 1.90 Virginin . . ft Corvi . . . 69 53 12 13 15.348 12 27 33. 735 +- a 0721 r ai3s - . IKM; . (Ki:n - . oofl + .0163 U .0041 .006 13 11 89 56 40. 07 112 40 39. S3 + 20.021 + 19. 910 0. 033 0. 062 + 0.029 i 0.069 + 1.86 + 1.87 42 POSITIONS OF FUNDAMENTAL STARS. MEAN POSITIONS FOR 1870.0 (JANUARY Orf. Od.16, WASHINGTON) OF STARS OF THE AMERICAN EI'IIK M El: IS, \ r. ( 'cuit iniii-d. Star. 1 . if 7 i 4 M Precession. Secular varia- tion. Proper motion. Corr'll to Am. Epliem., 1870. A i * o i o fi rf Precession. Secular varia- tion. Proper motion. CCIIT'II to Am. Eplicni.. 1.-70. h. m. s. s. s. s. ftp / // IT Draconis . 5 12 27 55. 31 + 2.612 .055 .011 + .02 8 19 29 41. 59 l- 19. 906 0.054 + 0.023 1.32 32 2 Caiuelopanli . 9 12 48 13. 51 + 0.362 + .222 .012 + .50 11 5 52 48. 81 + 19.612 0.018 i- 0.030 2.02 a (Jaiium Ven. . 71 12 4!) 56. 627 + 2. 8379 . 0151 . 0204 + .027 13 50 58 4.1.11 19. SSI _ 1). 036 - 0. Hill + 1.04 Virginia . . 83 13 3 13. 268 + 3. 1030 + .0077 . 0024 .OH 12 94 50 40. 76 + 19. 297 - 0. 130 i- 0.040 + 2.09 a Virginia . . 200 13 18 20. 852 + 3.1551 t- .0114 . 1:024 + . 015 22 100 28 55. 51 f 18. 894 - 0. 161 i- 0.034 :- 1.46 Virginia . . 94 13 28 4. 261 + 3.0715 1- . C063 . 0189 + .029 17 89 55 49.74 + 18. 592 0. 173 I). ODD + 1.59 TI UraD Majoris . 24 13 42 24. 99 + 2.3844 .01113 .0102 .00 13 40 2 13. 61 18.0*7 0. 156 0. 020 ' II. OH rt Bootis . . . inc. 13 48 29. 713 + 2.8617 .0005 .0031 .016 19 70 56 59.35 + 17. 851 0. 197 f 0.360 i- 1.81 a Draconis . . 13 14 52. 30 + 1.629 + . 0052 .007 + .04 12 25 8.22 + 17. 330 0. 136 \- 0.034 -1.38 a Bootis . . . 186 14 9 43.975 + 2.8131 + . 0023 . 0798 + . 033 22 70 8 23. 46 + 16. 927 0.214 + 1.970 t- 1.99 6 Bootis . . . 18 14 20 46.31 + 2.0697 . 0013 .0266 + .08 13 37 32 51. 22 + 16. 390 0. 176 i- 0.409 D.W 5 Ursa? Miuoris . 13 14 27 49.96 0. 219 + .122 + .005 + .13 11 13 43 33. 95 + 16. 025 0.012 + 0. C20 1.43 c Bootis . . . 88 14 39 18. 612 + 2.6241 . 0001 .0025 + .009 15 62 22 35. 79 + 15. 402 0. 250 0.011 ; 1.35 a 2 Libra) . . . 81 14 43 41.416 + 3.3150 + .0155 .0085 + .016 14 105 30 0. 22 + 15. 153 0. 321 + 0.054 + 1. 74 UrsseMmoris . 57 14 51 6.66 0. 244 + .104- .007 + .02 17 15 18 47. 57 + 14. 720 + 0.020 I- 0.029 - 1.34 fi Bootis . . . 6 14 57 2. 89 + 2.2637 .0000 .0038 .06 49 5 . . + 14. 362 0.235 + 0.060 | . . /? Librae . . . 91 15 10 0.866 -|- 3.2265 + .0118 .0067 + .031 16 98 54 6. 02 + M. 548 0. 3.11 i 0.009 + 3.23 ft Bootis . . . 88 15 19 34. 843 f- 2.2780 + . 0012 .0102 + .018 8 52 9 56. 26 + 12.919 0. 257 0. 091 r 0.61 y TJrstc Minoris . 6 15 20 57. 15 0. 148 + .075 .000 .07 6 17 42 11.57 + 12.827 + 0.012 0. 029 0.30 a Corona? Borealis 140 15 29 11.084 + 2.5296 + .0024 + .0097 + .027 21 62 50 47. 50 + 12. 265 0.299 + 0.063 + 1.85 a Serpentis . 102 15 37 51. 987 r 3.9417 + . 0061 + .0085 + .051 21 83 9 49. 83 + 11. 656 II. .-,.1.1 0. 06.P 4- 1.91 Serpentis . 45 15 44 2il. 269 + 2.9776 + . 0065 + .(1091 + .026 13 85 7 45.52 + 11. 190 0. 367 0. 069 + 1. 31 Trail* Minoris - 13 15 48 45. 50 2. 303 1- .204 + .013 + .15 11 11 48 24. 52 + 10. 867 + O.S77 + 0.003 0.22 o Scorpii . . . 35 15 52 39. 031 + 3.5368 + . 0160 .0009 + .041 7 112 14 58.73 + 10. 579 0. 442 + 0.011 2. " /?, Scorpii . . 31 15 57 52, 891 + 3.4787 + . 0142 . 0020 + . 058 9 109 26 50. 88 + 10. 187 0. 440 + 0.020 + 0.95 <5 Opluuchi . 47 16 7 32. 118 + 3.1413 + . 0083 . 0037 + .053 17 93 21 27. 90 + 9. 451 0. 407 -i- 0. 139 + 8. 1* r Herculis . . 18 16 15 50. 13 + 1.8008 + .0052 .0029 + .21 13 43 22 33. 26 + 8.805 0.239 0. 031 + 0.26 a Scorpii . . 67 16 21 26. 431 + 3.6686 h .0152 .0001 + .021 11 116 8 28. 19 8.361 0. 489 + 0.020 1. .12 n Dracouis . . 9 16 22 14. 18 + 0.8012 + .0185 + .0220 + .02 3 28 11 27. 40 + 8.297 0.110 0.080 0.36 A Draconis . 7 16 28 14. 94 0. 144 i- . 041 + .001 .01 8 20 57 2. 80 + 7. 816 + 0.016 0.034 -|- 0. 39 g Ophiuchi . . 4C 10 30 0. 163 + 3.2066 -1- . 0079 + .0012 + . 030 16 100 18 6.14 + 7. 675 0. 447 0. 031 i- 2. 31 i? Hercutis . . 18 16 38 26. 43 + 2.0511 + . 0038 + .0032 + .04 9 50 49 44.98 + 6. 987 0. 3---1 + 0.071 ;- 1. 55 K Ophiuchi . 59 16 51 3). '.174 + 2.8565 + . 0044 .0319 + .070 11 80 25 15. 20 + 5. 904 0. 394 0. 023 4. 1.4.1 c TJrsno Minoris . 11 16 59 22. 74 6.405 + .302 + .015 .09 15 7 45 10.66 + 5. 243 + 0.901 0.000 0.25 a Herculis . . 115 17 8 43. 263 + 2.7339 + . 0035 .0008 + .049 17 75 27 34. 86 + 4. 450 0.390 0. 049 1.11.1 b Opliiuchi . C9 17 18 26. 000 + 3.6591 i- . 0075 .00114 + .058 11 114 3 11.51 + 3. 618 0. 526 + 0.120 + 3. 14 o Ophiuchi . . 138 17 28 54. 069 + 2.7746 + .0033 + .0074 .062 20 77 20 36. 52 + 2. 713 0. 404 i- 0.200 + 1.65 o> Draconis . 10 17 37 42. 96 0. 364 -i- .011 + .000 + .06 11 21 10 55. 83 1- 1.947 I- 0. 050 0. 291 1.94 fjt Herculis . . 73 17 41 22.380 f 2.3696 + . 0038 .0249 + .033 12 62 18 6.33 + 1. 629 0. 338 + 0.740 + 1.72 i// 1 Draconis . . 5 17 44 15. 24 1.086 + .019 + .002 .06 4 17 47 17.40 + 1. 377 i- 0.157 + 0.260 1 0.41 Y Draconis . 19 17 53 35. 37 r 1.3910 -|- . 0036 + .0017 .03 14 38 29 -11.96 + 0.561 0.202 i- 0.037 + 0. 36 y z Sagittarii . . 25 17 57 27. 502 + 3.8572 + . 0035 .0049 + .040 3 120 25 22. 14 + 0.222 0. 561 + 0.231 + 0. 57 p Sagittarii . 94 18 5 59.375 + 3.5876 + . 0010 .0015 + . 035 6 111 5 24.82 0. 524 0. 522 + 0.011 + 1.14 6 TJrsaj Minoris . 18 14 16. 33 19. 435 .430 f .028 .03 38 3 23 38. 84 1. 249 + 2. fc20 o. on ) 0. 14 n Serpentis . 22 18 14 35. 034 f 3.1405 + .0018 .0411 + .085 5 92 55 49. 72 1.275 0. 445 + 0.680 + 2.06 1 Aquilte . . . 91 18 28 8.001 + 3.2665 -i- . 0001 .0022 |- . 097 12 98 19 57. 58 2.456 0. 471 1 0. 329 + 1.51 a Lyi'ce . . . 177 18 32 32.263 2.0131 + .0010 + .0184 + .051 16 51 20 9.66 2.838 0. 295 0. 286 + 0. 66 ff Lyras . . . 64 18 45 16. 873 -1- 2.2138 + . 0015 4- .0004 + .061 9 56 47 12. 62 3. 937 0. 315 I 0.029 + 0. 71 a Sagittarii . . 40 18 47 12.258 + 3.7234 .0051 4- -0003 + .037 8 116 27 20.08 4. 1U2 0.530 + 0.080 1.9.1 50 Draeoms . . 13 18 50 33. 35 1. 893 .0557 . C04 + .24 11 14 43 14. 56 4. 388 + 0.271 0. 057 1. 15 Aquilrc . . . 24 18 59 26. 137 + 2.7579 + .0004 .0030 + .100 13 76 19 40. 52 5. 143 0. 386 + 0.071 ;- 1.32 A Sagittarii . 8 19 10 1.6S5 + 3.5156 .0060 .0012 + .046 III!) 10 . . 6.032 0.486 0.011 i Draconis . . 15 1 19 12 3J.21 + 0.015 .023 + .019 + .10 li 28 34 1.63 6. 240 0. 005 0. 066 6.55 T Draconis . . 3 19 18 2. 46 1.080 .058 . 026 + -21 5 16 53 12. 16 6. 698 4- 0. 149 0. 097 0.44 A Aquilffi . . . 73 111 1* 56.643 + 3.0096 .0018 f .0152 + .083 14 87 8 33. 03 6. 772 0. 415 0.100 + 1.61 K Aquihu . 46 19 29 53. 846 ]- 3.2308 .0044 .0003 + .074 14 '.17 1- .12. 0.1 7.666 0. 432 0.000 -|- 2. 40 y Aquilfo . . . 86 19 40 4. 792 + 2.8520 . 0010 + .0008 + .059 13 79 42 7. 12 8.482 0. 374 0. 006 + 1.68 a Aquilre . . . 128 19 44 26.460 + 2.8921 .0018 + .0362 + .073 1.1 M 88 23.81 8. 836 0. 385 0. 383 + 1. 19 s Draconis . 5 19 48 36. 14 0. 185 .043 + .014 + .18 i; 20 3 17. 26 9.151 0.034 -I- 0.003 1.50 /? Aqnilse . . . 63 19 48 55. 678 + 2.9454 .0014 J .0015 + . 062 9 83 54 Sa .1" 9. 177 0. 379 + 0.483 + 1.48 A Ursit- Minoris . 33 19 54 16. 00 59. 083 211. 9.14 .071 .38 13 1 4 .1.1. .16 9. 591 + 7.605 0.014 II. .12 T Aquihi 1 - . . 23 III 57 47. 380 2.9310 , on-ill -- .011:17 + . 047 6 83 5 14.56 9. 860 0. 369 0.011 a, n a 8 Capricorn! . 85 411 111 5'i. Illl 3. 3307 . 0085 .OOSM + .070 M 102 .16 45.16 10. 837 0. 405 0. 005 (- 1.14 K Cephei . . . 7 20 13 13.3.1 1. 894 . ir.4 + .002 + .24 4 12 40 53. 98 11.012 0. 2)3 0.000 0. 95 IT Capricorn i . 20 20 19 52. 715 + 3.4418 .0115 .0000 + .057 9 108 38 9.70 11.494 0. 407 0.020 + 1.90 Delphini . . 42 20 27 0. 1711 + 2.8666 . 01)13 . 0000 + . 079 11 79 8 13.57 11.999 0. 330 0.000 [ 1.83 a Cygni . . . 53 20 37 0. 07 1- 2.0434 + . 0022 + .01:05 + .05 12 45 10 59. 75 13. 689 0. 226 0.000 + 0.48 H Aquarii 58 20 45 38. 473 -[- 3.2394 .0083 .11(110 + .098 12 99 28 10. 59 13. 265 0.350 + 0.040 j- 2. 24 v Cygui . . . 24 20 52 19. 70 + 2.2331 + . C037 + .0006 + .09 10 49 19 56. 60 13. 698 0.232 0. Oil 1. -1 lil'Cviiui . . . 22 21 1 4. 2! 13 + 2.3340 + .0149 . 3390 . 00.1 10 51 53 19. i2 14.247 0. 300 3. 220 -I- 0. 1-9 S Cygni . . . 84 21 7 24.265 -f 2.5507 4- . 00:19 . 06 ; . 038 18 60 18 19.07 14. 632 0. 240 + 0.071 1. 1.1 1 0. COO I.HI POSITIONS OF FUNDAMENTAL STAUS. 43 MI:\N I'osmnxs FOI; i>7o.(.r.\xrA!:Yo,i_o.;.ii!. WASIIIM; TIINM>FSTAI;SOF TIIK AMKKICAN i:rin:Mi:iils,&c.-ConUinied. 1 | ~ = n \ | sg Star. "= I i 3 J j 2 '1 a 1 3"] "=i ^ = ? *ci H R J: '- s q B 3 - P fcf li 9 g e ''** ri h * fi C^ ri < * at h. m. t. g. ( t O ' '/ :ilH'i -.11 21 2li >. 4C. 031 i .oos + .10 15 20 35. 00 15.748 0.066 + 0.037 0.93 A'|ti:it li . 81 21 30 C'. -13 3. 11124 - .ton 2 + . 047 5 98 26 9. 77 15. 955 0.277 0.040 + 1. 58 C IY- r ;ihi H 21 37 1- 117 i 2. '.1451 .0000 -j- . 0028 . . 037 18 80 43 11.87 Hi. 317 0. 244 0.000 + 1.25 11 C.ph.i . . . 10 -.'1 III 0.5.-, . 0319 + .026 .00 9 19 17 12.61 16. 428 0. 071 0.071 0.86 fi Capricorn! . 37 21 46 12. 13^ .0114 . 0-J30 1- -'" ;l 9 104 9 45. 35 16.734 0.259 0. 020 + 2.36 79 Drao.nis 8 21 51 15.02 + 0.730 .015 .IKK + .06 8 16 54 44. 65 16.973 0. 051 + 0.009 0. % > f) ~ t < '{1|| + 3.1636 ] .0077 . . 0070 : . O.VI 12 47.54 17.7HS 0. 207 o. ogii ; 1. 57 - Aipiarii . . 41 19 1- 3- 2!i 1 -j 3. (H150 .00-^ i . 0001 + .047 10 i Hi 54. 14 18. 125 0. 184 + o. on -f 1.59 n A.puirii . . I- in. :,-i .0032 .01111 on 10 IKl 17 13. 14 18.483 0. 168 + 0.060 + 1.43 I Pt-nasi . . 12 gg :ii :,-. -.c.-. on-'-' i- .0030 + . 093 11 79 50 48. 60 18. 691 0. 151 0.000 r 2.06 t (Y|.ltri II 3. :,3 2. 1211 n. 'T .012 . 12 'i - 58.44 is. tog 0.091 i 0. 1 III 0.50 \ Aqiiiti ii 41 22 4.-, 111. 1127 : 3. ]:'! .0064 . IKI21I + . 107 9 '.If 16 15.36 19.014 0. 138 II. 029 i 1. 90 a Pisris Australia !; 22 M 27. 7H5 :i. 305i; .0214 .11211 . lid:, 20 120 i :K ii7 19. 1311 0. 139 ) 0. 169 + 1. 52 a p..giwl . . . -1 17.240 2. H.-OI + .0056 + .0043 + .060 17 75 29 38. 08 19. .132 0. 108 t- 0. 0011 + 1.81 (Vphri 8 1 23 13 1 . + 2.422 + .040 + .014 .03 9 22 35 58. 11 19. 640 0.064 + 0.020 1.35 Piscium . . 1- SI 21 22. 501 + 3. 0499 .0021; . (KI92 .0-7 13 84 20 6.37 19.771 0. 067 + 0.060 + 2. 31 ( IMsi'iuill tig 2:1 :ct 15 :>" + 3.0587 -j- . 04130 . ii J.'i- + .028 11 85 4 41. 96 19.919 0. 045 0.451 -f- 1.41 y (Yphci . . . in 2:1 31 2.01 2. 4-.-J .1171 .021 f .24 17 13 5 34. % l'J.926 0. 031 0. 1411 - 0.27 ') Pisrium . . 57 23 52 38. 243 + 3.0675 + .0047 + .0105 + .037 10 83 51 24. 09 20. 045 0.007 + 0. 129 + 1.72 COMPARISONS OF THE PRECEDING POLAR DISTANCES WITH THOSE OF OTHER CATALOGUES. I ii the following list are found only the stars of the Tabulae Reductionum of Wolfers, which are arranged in the order of polar distance. The second column gives. the zenith distance of the star at upper transit over the meridian of Washington. The polar distances of the catalogue were compared with those of Wolfers for 1870, and the differeiK c is -i\ en after the zenith distance of the star. As the catalogue of comparison was really or substantially that of Wolfers, these corrections are applicable at the mean epoch of observation, lMiT.0. The corrections to Wolfers. deduced by Auwers, and given on page 111 of the additions to the Conna inxn arc -ivhten, No. 1C97, (Band 71, S. 257-264,) Gylden gives several com- parisons of the declinations of the Pulkowa vertical circle with those of other authorities, and especially a comparison of the declinations of the fundamental stars observed since 1863, with the normal catalogue, of Auwers. Applying these numbers to the column Auwers, we have a com- parison \\ith the Pulkowa verticle circle. Nearly all the fundamental stars were observed with the Washington mural circle during the years 1864 and 1S65. Carrying the results forward to 1870, the polar distances were corrected by the constant quantity, -f 0".47, for error of the latitude adopted in the reductions, and then sub- tracted from the polar distances of the transit circle. The differences are given in the last column. 44 POSITIONS OK FUNDAMENTAL STARS. COMPARISONS OF THE PRECEDINli NORTH POLAR DISTANCES WITH THOSE Of OTHER AUTHORITIES. Star's name. Zenith distance. Apparent corrections to the polar distance of Wolfer's Tab. Red. Auwer's Standard. Greenwich transit circle. Pulkowa vertical circle. Washington mural circle. o Polaris .... 310 0.05 0.05 0.07 0.05 4- 0.27 S Ursa) Minoris . 312 0.83 0.20 0.16 4- 0.65 4- 0.3 ft Ursa) Minoris . . 324 1.73 1.17 0.51 0.10 0.3 3 Cepliei .... 329 1.27 1.06 0.54 4- 0.03 0.2 a Urs Majoris . 336 0.62 0.34 0.40 4- 0.85 4- 0.6 a Cephei . 336 0.93 0.80 0.43 4- 0.48 4- 0.2 a Cassiopeos . 343 4- 0.43 0.31 4- 0.01 0.02 4- 0.3 y Ursa) Majoris . 344 + 0.39 4- 0.32 4- 0.03 4- 0.53 4- 0.4 y Draconis . . . 347 + 0.36 0.03 4- 0.04 0.03 - - tl Ursa) Majoris . 349 4- 0.29 0.05 0.35 0.03 . . c. Persei . . . . 350 0.26 0. 26 0.07 4- 0.20 . o Aurigse .... 353 4- 0.79 4- 0.39 0.05 4- 0.21 4- 0.7 a Cephei .... 354 4- 0.74 4- 0.44 4- 0.29 4- 0.42 0.6 a Lyra? .... 4- 0.99 4- 0.36 0.04 4- 0.34 0.1 o 2 Geminorum 7 4- 0.96 4- 1.51 4- 1.07 4- 0.82 4- i.o 3 Tauri .... 10 4- 0.25 4- 0.68 4- 0.43 4- 0.70 4- 1.8 a Andromeda) 11 + 1. 52 4- 0.84 4- 0.32 4- 0.28 4- 1.2 j? Geminorum 11 4- 0.70 4- 0.83 4- 0. 64 4- 0.25 4- 0.7 a Coronas .... 12 4- 2.30 + 1.55 4- 0.98 4- 0.88 4- 1.4 a Arietis .... 16 + 1.22 4- 1.25 4- 0.50 4- 0.40 4- 1.4 o Bootis .... 19 4- 1.88 4- 1. 29 4- 0.89 4- 0.36 4- 1.3 a Tauri .... 23 4- 1.79 4- 1.32 4- 0.43 4- 0.62 4- 2.0 /? Leonis .... 24 4- 1.45 4- 1.28 4- 0.62 + 0.68 4- 1.2 a Herculis 24 4- 1.61 4- 1.12 4- 0.39 4- 0.24 4- l.o a Pegasi .... 24 4- 2.15 4- 1.47 4- 0.66 4- 0.29 4- 0.4 y Pegasi .... 24 4- 1.02 4- 0.90 4- 0.20 4- 0.03 4- 0.8 a Ophiuchi 26 4- 1.92 4- 1.67 4- 0.87 4- 0.17 4- 1.2 o Leonis .... 26 4- 0.92 4- 0.89 4- 0.40 4- 0.32 4- 0.7 y Aquihe ..... 29 4- 1.64 4- 1.52 4- 0.83 4- 0.83 4- 0.8 a AquiliB .... 30 4- 1.19 4- 0.90 4- 0.43 4- 0.26 4- 1.2 o Oriouis .... 32 4- 0.74 4- 1.49 4- 0.80 4- 0.49 4- 2.8 a Serpeutis 32 4- 1.79 4- 1.67 4- 0.90 4- 0.54 4- 0.6 f) Aquila) .... a Ceti 33 35 40 4- 0.90 0.05 4- 0.99 4- 0.85 4- 0.33 4- 1.37 4- 0.52 4- 0.45 4- 0.69 4- 0.28 0.34 4- 0.57 4- 1.2 4- 0.9 0.4 a Aquarii .... a Hydra) .... 47 4- 1.27 4- 1.05 4- 0.52 4- 0.59 4-' 0.8 /3 Orionis .... 47 4- 0.45 4- 0.73 4- 0.22 4- 0.46 + 0.7 a Virginis .... 49 4- 0.81 4- 0.59 4- 0.49 4- 0.54 4- 0.3 a" Capricorni . . . 52 4- 0.86 4- 0.66 4- 0.48 4- 0.15 4- 0.3 a 2 Librse .... 54 4- 1.50 4- 1.10 + 0.52 4- 0.48 4- 0.7 a Scorpii . 64 4- 1.75 4- 0.84 4- 1.21 4- 0.2 a Piscis Australia . 69 4- 0.81 4- 0. 97 4- 0.26 - - 4- 0.8 POSITIONS OF FI'NDAMKNTAL STARS. 45 Ccrl ain features of these comparisons may at t met attention. Commencing with the last column, \\c lind that the discordance between the results of the mural and the transit circle exhibits the same curious property with the discordance between the direct and reflection observations with the transit circle, namely, that instead of varying continually it is scarcely sensible, accidental errors exceptcd. from the pole to the xeuith, and that it there suddenly acquires a sensible value, which it retains with no change, except a slight diminution through the remainder of the arc within which observations are included. Comparing this result with the difference between the latitudes given by the two instruments, namely, 0".4S,* we find the general result to be that the zenith distances measured with the transit circle are constantly greater than those measured with the mural by a bout half a second of arc, whether the measure be made north or south. The variations from this law are hardly greater than maybe due to the errors of division of the mural circle and the accidental errors of observation. This phenomenon is the more interesting that it gives us an instance of those systematic dis- cordances between the polar distances of stars given by different authorities occurring in the case of two instruments in the same building under similar atmospheric conditions. So far as I am aware, Faye is the only astronomer who has ever framed a general theory to account for these dis- cordances. He has attributed them to undetermined flexure of the instruments and local refrac- tion, and has presented a number of ingenious devices for determining an instrumental flexure of the form 2 sin 2Z -(- 6 2 cos 2Z + 03 sin 3Z + etc. The existence of any flexure other than that of the form a sin Z + b cos Z seems to me highly improbable. A well fitted instrument niay be regarded as a solid body, held in equilibrium by the opposing forces of gravity on the one hand, and the action of the counterpoise roller on the other. And that must be a very badly made instrument in which the effect of the latter action in altering the relative positions of the eye-piece and object-glass is different from what it would be if, as the instrument revolved, it always acted rigorously upon the same particles of the instrument like that of gravity. It is also laid down by physicists as an observed law of matter that the change of form which a body undergoes through the operation of a force, which is only a small fraction of the rupturing force, is proportional to the intensity of the force. Now, from the two hypotheses, (1), that a revolving body is held in equilbrium by opposing forces always acting in the same direction and on the same parts of the body ; and, (2), that the change of position is proportioned to the force, it follows rigorously that the small change of positioli of any part of the body relatively to any system of co-ordinate axes revolving with it is of the form sin Z + b cos Z without any terms depending upon the multiples of Z. This proposition is demonstrated in the Description of the Transit Circle, 40, 41. Iii applying this hypothesis to an actual instrument it is presupposed that all the parts of the latter which are in contact in one position are equally in contact in every other 'position.t There must, therefore, be no play between the parts of the instrument. If these hypotheses are not applicable, the flexure will be altogether irregular, and not capable of representation by a periodic series unless we take an immense number of terms. * The latitudes arc as follows : o / a From mural circle observations, 1861-64 38 53 38. 78 From transit circle observations, 1866-67 38 53 38.30 t An an example of the failure of this hypothesis, suppose the body A B turning P round O, and sawed nearly through at P. If, in the position represented, the surfaces ^ " Q~~| ~ g of P'were separated by the weight of the end B, while in the reverse position they were pressed into contact by the same weight, then the law of flexure would not apply, as there would be a break in its continuity at those points of the revolution where the contact and separation of the surfaces occurred. 46 POSITIONS OP FUNDAMENTAL STARS. Moreover, the preceding comparisons of the polar distances deduced from the observations of Pulkowa, Greenwich, and Washington, as well as the comparison of direct and reflection observa- tions made here, seem to render the existence of flexure depending on the multiples of Z very improbable, there being an arc of 40 or 50 through which no well marked change occurs. That the difference in question is due to local refraction seems improbable from the similarity of the circumstances in which the two instruments are placed. But there is an alfied cause which may not have been without effect. The differences of external and internal temperature which give rise to loctil refraction are due to the difference between the temperature of the external air and that of the walls, floor, and roof of the observing room. Astronomical instruments are thus subjected in rapid succession to radiation from a roof heated by the sun, to accidental currents of warm air from the heated roofs and walls, and to currents of cool external air. The possible effect of these causes on the instrument maybe judged from the circumstance that if one end of the tube of the transit circle telescope were unequally heated, so that one side of it should be one degree Fahrenheit higher than the other, such heating would alter the pointing by 3". The only reason I have to believe that this cause did not act injuriously, is that the results of day and night observa- tions, when it acted in opposite directions, do not appear to exhibit any great systematic discord- ances. During the year 1869 the transit circle was mounted in a new observing room which was designed with especial reference to securing the nearest possible equality of the internal and exter- nal temperatures. UII7IESIT7 v-Jj H|YW i -^Mff^^m ' ft -A | r v p.', ' MP . -^--.,'^M^'-' ^' -^^, W OOA^,, ,,,,,; ^^, iS^f^fp^ Ml $ ^ ^ v- w in, ,,^^^ r g ., " ' ^ ' \ Newconb, S. 63966 roaitions of fundamental stars. 'ijfftwvffffWffito ^C>n'\oOC^^ IA, ^^ ^yvyvvv UNIVERSITY OF CALIFORNIA LIBRARY >> ! JW -^^^;: - ^ W2 ' ;