702 J. B. HANNAY ON A METHOD OF DETERMINING, ETC. 
The neck of the drop was measured at the breaking-point, and the measure- 
ments were made as free from error as possible by having the growth-time very 
long, and following in the decreasing neck, till it was seen to give way. The 
average of a large number of readings gave 3°395 mm. as the diameter of the 
neck at 16° C. From rad.” x 7, we find 9:0526 square millimetres as the area 
of the neck, and from pees 
area, 
millimetre of liquid. Experiments made with varying temperature show the 
general result that the cohesion decreases with a rise of temperature faster 
than the density ; but the difference is so slight, that a very mimute investiga- 
tion would require to be made before a formula could be given. 

we find a breaking strain of 0-0456 grm. per square 

