Majichcster Memoirs, Vol. Ivi. (19 12), No. J). 3 



bounding spheres was in each case one inch, so that if 

 d is the diameter of the internal sphere in inches, the area 

 of any section parallel to the base is -k {d-\- 1) square inches. 

 The vertical breaking stress is found in pounds per square 

 inch by dividing the breaking load by the area of the 

 section. 

 The top was plane and parallel to the base. 



The specimens i. and la. had the dimensions: — 

 internal diameter, I2"5 inches, 

 external diameter, 145 inches, 

 height, 575 inches, 

 and I a. was reinforced at the base with two rings of 

 wire one-sixteenth inch diameter, a quarter of an inch 

 from the bottom. 



I. The longitudinal cracks first appeared under a 

 load of 3-35 tons, and spread up the dome 

 as the load increased, reaching about three- 

 quarters or four-fifths the height when the 

 specimen broke latitudinally under the load of 

 4*42 tons, or a vertical breaking stress of 233"61bs. 

 per sq. inch. Care was taken in removing the 

 specimen from the machine, the lower portion 

 coming away in pieces, while the top remained 

 intact, 

 la. The longitudinal cracks first appeared under the 

 load of 4'Oi tons, and in this case started from 

 ■* the top, spreading gradually downwards. When 

 the cracks had reached about two inches from 

 the base the specimen broke latitudinally, as in 

 the previous case, under the load of irii tons, 

 or a vertical breaking stress of 5867 lbs. per 

 sq. inch. Part of the top collapsed, but the 

 bottom remained whole. 



