167 
a floating colimator. 
obtained a much better image. These observations were 
made in extremely damp weather, and the support had been 
kept for a few days in a very dry place. 
2d Set. 
Divisions 
of 
Microm. 
Difference. 
Error in Sec®. I 
affecting the 
Horiz. point. 
Dec. 8 
0 raised - 
31*6 
After an hour’s interval 
Lanthorn close to wires 
16,6 
19.9 
+ 3.3 
+ 0.99 
' 
After an hour - 
Out and replaced, S first 
Ditto, - E first 
Ditto, - 0 first 
0 raised and carried 
S raised and carried 
Ditto, read again - - - 
Carried box, kept as level as possible 
S raised and carried - - 
Out and replaced, S first 
8,8 
> 3.7 
> 3.1 
> 3 .> 
>>.5 
>1.7 
10,7 
5.2 
3.5 
0,5 
+ 4.9 
— 0,6 
0,0 
— 1,6 
+ o,z 
1,0 
— 5.5 
— >.7 
— 3.0 
+ >.47 
— 0,18 
— 0,00 
— 0,48 
+ 0,06 
— 0,30 
— 1,65 
— 0,51 
— 0,90 
The wooden float being designed merely for preliminary 
experiments, and it not being my intention to introduce any 
errors but such as might arise from moving the float or agi- 
tating the mercury, I had a float made of cast iron eight 
inches long, four wide, 0,2 thick, and weighing 2 lb, 5 oz, 
troy. The telesccope was tied firmly to the Y s. 
