of Edinburgh, Session 1871-75. 627 
Curve III. is in this experiment not so good as curves I. and II., 
but the mean result from it makes 
perature of 20 C. 
K 
cp 
'257 with a mean free tem- 
India-Rubber, No. II. 
= 2*480 ; mean free temperature, | j 30° C ; j jjj' | 0 C. 
Junctions. 
Vo 
2/i 
y-2 
2/3 
2/4 
2/5 
2/6 
2/r 
i 
a 
I. 
9*4 
13-7 
15-6 
13-0 
8*2 
3*2 
0-4 
4*7 
0-69 
7-12 
7J5 
II. 
3*8 
7-7 
11-2 
12-0 
9-0 
5*1 
T4 
0-9 
- 2*80 
oo 
5-62 
III. 
0-5 
2-7 
6'7 
9*8 
9 '4 
6-5 
3-0 
0-8 
-4-49 
op 
4 85 
18 
95° 32' 
60° 06' 
22° 17' 
II 
II. 
III. 
j’ } Ioge 7 = 0 '24078; /?- /S' = 35“ 26' = 0-6190 radians; 
= 0-1080 . 
cp 
} log* = 0-14739 ; ft - ft' = 37° 49' = 0-6607 radians. 
' a! 
Cp 
- = 0*1653 . 
These experiments seem to show, in the case of the india-rubber, 
a very marked increase in the value of — with a decrease of tem- 
cp 
perature; but, unfortunately, the late period of the session at which 
the specimens were obtained prevented our repeating the experi- 
ments, which probably give too high values. We have not yet 
been able to obtain values for c, but hope to do so at some future 
time. The values for p are roughly — for gutta-percha, p = 097; 
for india-rubber, p= 1T7 at the temperature of 18'8° C. 
In conclusion, our thanks are due to Prof. Tait for the use of his 
laboratory, and the kind assistance which he gave us in our experi- 
ments; to Prof. Jenkin, through whom we obtained the specimens; 
and to Messrs Siemens and Hooper for the care with which these 
specimens were prepared. 
4. A Chapter on the Tides. By the Rev. James Pearson, 
M.A., Vicar of Fleetwood. Communicated by Professor 
Tait. 
4 M 
VOL, VITI. 
