Stromever, Explosions of Steam Pipes. 



These experiments have an important practical bear- 

 ing on the question of steam-pipe explosions as shewing 

 that, when the material receiving a blow is of a plastic 

 nature, the blow is materially weakened in its effects. 

 Dr. Hopkinson's experiments do not prove that it requires 

 twice as great a velocity to tear a wire at the bottom as it 

 does to tear it at the top, nor is it possible, except with a 

 brittle material (as, for instance, glass), to demonstrate 

 this deduction. I therefore arranged the following experi- 

 ment. A helical spring 1-40 inch diameter, consisting 

 of 268 turns of pianoforte wire 0-056 inches thick, 

 was suspended from a beam, the bottom was held down 

 by means of a very fine cotton thread, and was released 

 by burning it. At the same instant a photographic 

 camera on a revolving stand was set in motion. The 

 bright reflections of each turn of wire should have produced 



