6 GwYTHER, Modes of I'tipture of a heniisphei'ical sJiell. 



fracture roughly along a parallel of latitude, and, 

 as in the case of the former experiments, was 

 approximately conical, and nearly normal to the 

 spherical surfaces, although in each case the 

 vertex of the cone appeared to be in the axis 

 and slightly below the centre of the sphere. As 

 the rupture took place there was an extension of 

 the meridional cracks. 



lb. The longitudinal cracks first appeared under the 

 load of 603 tons at intervals averaging roughly 

 two inches round the middle of the dome, and 

 spread gradually up and down. When these 

 cracks had almost reached the top and bottom, 

 the specimen broke latitudinally under the load 

 of 20"35 tons, giving a breaking stress of 

 I074'8 lbs. per sq. inch, the average height being 

 about three inches. The specimen was removed 

 from the machine in two pieces. 



2b. Longitudinal cracks appeared round the middle 

 as in lb., in this case under the load of 7'i2 tons, 

 spreading gradually as the load increased. At 

 the load of 2063 tons, a breaking stress of 

 14707 lbs. per sq. inch, the specimen broke 

 latitudinally, the longitudinal cracks not having 

 reached the reinforcements at the top or base. 

 Again the latitudinal crack was irregular and was 

 at an approximate mean height of 2f inches from 

 the bottom. 



3b. Longitudinal cracks first appeared in meridian 

 planes under a load of 8'5 tons and spread as in 

 the other cases, but ultimately reached both 

 reinforcements, the whole breaking and falling to 

 pieces under a load of 2r2 tons, having sheared 

 through at the level of the reinforcements. The 



