On the Resistance of Glass Globes and Cylinders to Collapse. 537 



The specimens were crushed almost to powder by the violence of 

 the concussion ; it appeared, however, that the fracture occurred in 

 vertical planes, splitting up the specimen in all directions. Cracks 

 were noticed to form some time before the specimen finally gave 

 way; then these rapidly increased in number, splitting the glass 

 into innumerable prisms, which finally bent or broke, and the 

 specimen was destroyed. 



The following Table gives the results of the experiments upon the 

 cut cubes of glass : — 



Hence, comparing the results on cylinders with those on cubes, we 

 find a mean superiority in the former case in the ratio of 1-6 : 1, 

 due to the more perfect anneahng of the glass. 



On the llesistance of Glass Globes to internal 2ir assure . — In these 

 experiments the tenacity of glass is obtained by a method free from 

 the objections to that before detailed. Glass globes, easily obtained 

 of the requisite sizes, in a nearly spherical form, were subjected to 

 an internal pressure obtained by means of a hydrauHc pump, uni- 

 formly and steadily increased till the globe gave way. The Hues of 

 fracture radiated in every direction from the weakest part, passing 

 round the globe as meridians of longitude and splitting it up into 

 thin bands, varying from J^th to |th of an inch in breadth. 



The following Table gives the results of the experiments on the 

 resistance of glass globes to internal pressure : — 



