lxx INTRODUCTION TO THE MAKERSTOUN OBSERVATIONS, 1845 AnD 1846. 
The observations of September 11 and 13, made at three distances only, were 
reduced by the formula 
m_ Aja+AB+ Asy 
Xe, a+PBt+y 
where 
2 2 ge Sire vot 1 1 
gs — 88 gs St a en ee == 
a ae » B= ae ’ = ae > 2b r Se ry? 63 rs 
A, =3 7° sin 4, A, =4 7,3 sin w, As = 373° sin ug 
The observations of vibration were made in the usual manner, the following 1s 
a specimen of the details :— 
Table 16. Observations for the Time of Vibration of the Collimating Deflector M, 
June 15, 1847. 
North End of Magnet moving East. North End of Magnet moving West. 
Time of : i i - | ime of 
Transit. : ransit Vibrations. 
hm 48. .- m™m, 2 m 5 . m . . mm. 8. m. s. 
6 21 41-5 Bs 25 24-7 6 : 21-7 | 25 24-9 
22 12-0 . 24-8 : 52-0 24.7 
42.4 . 24-7 : 22-5 24-7 
13-1 : 24-6 : 53-0 24:7 
43-5 “2 24-7 * 23-3 24.5 
14-0 : 24-7 : 54-0 24-7 
44.5 5 D 24-6 : 24.4 24-8 
15-0 D 24-6 : 55-0 24-7 
45:5 : 24.6 5 0. 25-5 24-8 
3 16-1 H 24.5 . 56-0 24-6 
The observations of vibration were reduced by the formula already given (In- 
troduction, p. xxi). The formula for the time of vibration with the ring (Introduc- 
tion, p. xxii*), having the more convenient form 
a 
Be 
16 
2 8 2 feat Rln.d — 
o bigby G2 - = ) (1 -&/G=% + ofe=4+) 
The values of K the moment of inertia have been deduced by the formule al- 
ready given, pages xxi and xxiv. The times of vibration and the dimensions of the 
rings are given, page 352. 
The following are the results of the observations with the circle magnetometers :— 
* See Corrigenda, 
