2º Toughened glass resisted fracture until a weight of more than 510 lb. (255 kilos.) had been added, and then was not broken. The experiment was not carried to its limit for want of weights.
Rectangular plates, about 13 inches (0·325 m.) by 10 inches (0·248 m.) and 1/5 inch (0·005 m.) thick.
These plates were allowed to fall flat on to a floor of wood or thrown to a distance and allowed to fall.
1º Ordinary glass allowed to fall flat from a height of 1-2/10 inch (0·03 m.) was broken at the first trial.
2º Toughened glass. Thrown to a height 6 feet 6 inches (2 mètres) and to a distance of 13 feet (4 mètres) was also broken at the first trial. The piece, however, which had sustained the weight of 510 lb. did not break till the fourth trial.
Rectangular plates, about 10 inches (0·245 m.) by 6 inches (0·157 m.) and ¼ inch (0·007 m.) thick.
These plates were subjected to the same kind of tests as the foregoing. After raising them to a given height they were allowed to fall flat upon a wooden floor.
1º Ordinary glass raised to a height of 20 inches (0·50 m.) was broken on falling.
2º Toughened glass resisted successive falls of from 20 inches (0·50 m.), 32 inches (0·80 m.), 5 feet (1·50 m.), and 5 feet 7 inches (1·70 m.), but was broken when dropped from a height of 6 feet 6 inches (2·0 m.).
Rectangular plates about 10 inches (0·245 m.) by 6 inches (0·157 m.) and 1/5 inch (0·006 m.) thick.