le ad eens se ee ee ee Pe ae 
Trowbridge and McRae—Llasticity of Ice. 353 
s'f* 
Sa (37—@) 
Qa 
0 = 
3 tf a’ 
At another time we went where the old ice had been cut 
and anew crop about 5 cm. thick had formed. It was perfectly 
limpid and free from air bubbles. We sawed out half a dozen 
ore. The index consisted of a needle run through a piece 
of cork which was pasted on the ice and could not be jarred. 
A similar index was placed upon the supports to see if they 
he bars were smaller than the former ones and had a limit 
of perfect elasticity. In two cases the limit was exceeded, then 
Sinaller weights were put on and the bar was again perfectly 
lastic. The density of this ice was greater than that of the 
‘ce used in former experiments. It therefore appears that ice 
has a limit of perfect elasticity ifsmall bars are used, but that 
large beams, although elastic to a certain extent, gradually ae 
sorg their own weight. The results are given in tables 
The Symbols in the tables are: 
length of the span, 
temperature of the ice, 
density of the ice, 
breadth of the beam, 2 
depth of the beam, 
weight applied, : 
deflection of the beam from zero under a given load, 
the rise of the beam when the load is removed, 
modulus of elasticity using 9’, 
modulus of elasticity using S$, 
distance between the weights. ; 
The measurements are made in the C. G. S. system of units, 
R™2wegarnah 
Ue 
The temperature is given in Centigrade de 
rees. 
‘he values of e and ¢’ are given in absolute measure. 
I. Feprvary 12, 1885. 
- SEER Ee 
Ae | 30 -10-0 | +886) 22°6) 6:2 | 10,000 016 | 012 | 87 x 10° | 41 x 10° 
Mo re a 2 
