AT THE BOUNDARY OP A LIQUID IN MOTION. 
577 
manner which had been found to answer best, and a series of observations taken, one 
of which is given in detail : — 
Times of transit. 
32 l'5 
It 
10-5 
19 
28 
37 
45-5 
54-5 
3-5 
12 
■ 21 
30 
38-5 
/ if 
35 6-5 
Ij 
15-5 
24 
32-5 
41-5 
50 
59 
8 
16-5 
25-5 
34 
43 
.•. Time of 1 vdbration = 8''''794. 
Logarithmic decrement.—Zero I'O ; at end I'O. Readings at one end of 
swing:— 
42-2 
36-7 
32-0 
27-9 
24-3 
21-2 
18-5 
16-16 
14T7 
12-40 
10-90 
9-58 
8-44 
7-44 
6-60 
5-85 
5-20 
4-63 
4-16 
8-74 
3-37 
3-OG 
2-77 
Logarithmic decrement = T4273. 
The bulb was kept in a beaker of water whose tenipeiature could be easily 
observed, till just before each observation, when it was rapidly dried witli blotting 
paper, allowed to come to rest, and set oscillating by means of a strong bar magnet. 
The limit of each swing was read by means of a telescope mounted at the centre of 
a curved scale at about two metres distance, and the times of transit over the centre 
of the scale taken by a chronometer. 
The following determinations were made :— 
4 E 
MDCCCXC.—A. 
