430 



PHILOSOPHICAL TRANSACTIONS. 



[anno 1747-8. 



y Draconis. South of Preces- Aberra- 



38° 25' sion. tion 



1727 Septembei 3 70".5 — 0"4 + 19"2 



1728 March IS 108.7 — 0.8 — 19-0 

 September 6 70.2 — 1.2 + 19-3 



1729 March 6 108.3 — 1.6 - 19-3 

 September 8 69.4 — 2.1 + 19-3 



1730 8 68.0 — 2.9 + 19-3 



1731 8 66.0 — 3.8 + 19.3 



1732 6 64. 3 — 4.6 + 19-3 



1733 August . 29 60.8 — 5.4 + 19-0 



1734 11 62.3 — 6.2 + 16.9 



1735 September 10 60.0 — 7.1 + 19.3 



1736 9 59.3 — 8.0 + 19.3 



1737 6 60.8 — 8.8 + 19.3 



1738 13 62.0 — gd + 19.3 



1739 2 66.6 —10.5 + 19.2 



1740 5 70.8 —11.3 + 19-3 



1741 2 75.4 — 12.1 4- 19.2 



1742 5 76.7 —12.9 + 19.3 



1743 2 81.6 —13.7 + 19-1 



1745 3 86.3 —15.4 + 19.2 



1746 17 86.5 —16.2 + 19,2 



1747 2 86.1 — 17.0 + 19.2 



+ 

 + 

 + 



+ 

 + 

 + 

 + 

 + 

 + 



Nuta- 

 tion. 



8"9 

 8.6 

 8.1 

 7.4 

 6.4 



3.9 

 1.0 



2.0 

 4.8 

 6.9 

 7.9 

 9.0 

 8.5 

 7.0 

 4.7 

 1.9 

 1.1 

 4.0 

 6.4 

 8.9 

 8.7 

 7.6 



Mean 

 Dist 

 80"4 

 80.3 

 80.2 

 80.0 

 80 2 

 80.5 

 80.5 

 81.0 

 79.2 



79.9 

 80.1 

 79.6 

 79-8 

 78.7 

 80.0 

 80.7 

 81.4 



791 

 80 6 

 81.2 

 80.8 

 80.7 



I made about 250 observations of (3 Draconis; which I find correspond as 

 well with the hypothesis, as those of y ; but since the positions of both these stars, 

 in respect to the solstitial colure, differ but little from each other, it will be need- 

 less to set down the observations of j3. I shall therefore proceed to lay down some 

 observations of a small star that is almost opposite to y Draconis in right ascen- 

 sion, being the 35 th Camelopardali Hevelii in the British Catalogue. Mr. Flam- 

 steed indeed has not given the right ascension of this star; but that being neces- 

 sary to be known, in order to compute the change of its declination arising from 

 the precession of the equinox, I compared the time of its transit over the meri- 

 dian, with that of some other stars near the same parallel ; by which I found 

 that its right ascension was 85° 54-1-' at the beginning of the year 1737. 



This small star was compared with the same point of the limb of my sector, 

 as y Draconis; and the 2d column, in the following table shows how many seconds 

 it was found to be south of that point, at the time of each respective observation. 

 The other columns contain, as in the foregoing table, the equations that are ne- 

 cessary to find what its mean distance from the same point would have been, on 

 the 27th day of March, 1727, which is exhibited in the last column. The whole 

 number of my observations of this star did not much exceed 40; the greatest 

 part of which were made before the year 1730; in some of the following years 

 none were taken; and only a single one in any other, except in 1739. However, 

 their correspondency seems sufficient to evince the truth of the hypothesis: for 

 if the mean of these, contained in the table, be taken, not one, among the rest 

 of the observations, will difier from it more than 2". 



