8 



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 annealing of the glass. 



On the Resistance of Glass Globes to internal pressure. 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 hydraulic pump, uni- 

 formly and steadily increased till the globe gave way. The lines 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 -^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 : 



