Mr. Bevan’s account of an experiment, &fc. 305 
4 feet, I had a channel sawed on three sides of a paralle- 
logram, in the following form, a b c 
, separating the 
specimen to be operated upon, except at the end lettered a, 
where its union was left undisturbed. The dimensions of this 
prism was 100 inches long, 10 inches wide, and thickness at 
a = 3.62, at 6 = 4.00, and at r = 3.75 inches. To save some 
trouble in the calculation, I considered the thickness uni- 
formly 3.97 inches or the mean of the whole : although I am 
aware that it would not be strictly accurate ; but as the ex- 
periment was upon a large scale, and with weights up to 
25 lbs. and with deflections proportional to the weights 
applied, I considered the experiment a fair one. In this expe- 
riment the weights were placed at 98 inches from the line of 
union with the main body, and the deflection by 25 lbs. was 
0.206 inches ; from which I estimate the modulus to be 
2.100,000 feet. 
After this, I repeated the experiment on ice of various 
dimensions and of different thickness, and in all, the result 
agreed quite as near as the admeasurement of the thickness 
could be ascertained, as well when the deflection was tried 
upon the water, as when the ice was taken out and tried in 
the manner used with wood and metal. 
Now the modulus of water as given in your valuable lec- 
tures, derived from Canton’s experiment, is, if I recollect 
right, about 750,000 feet, calculated from a condensation of 
by the pressure of one atmosphere. This condensa- 
tion, I presume, was cubical or solid ; whereas the condensa- 
tion used in regard to the modulus of elasticity is linear. You 
are of course aware that a linear compression of j- 6 - q Q q will 
