PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 735 



about one inch long and one-third of an inch wide, with walls 

 about one-eighth of an inch thick. Lastly are constructed maga- 

 zines of honey and pollen, having their axes inclined to the hori- 

 zon, the entrances to which are in the highest part, so that the 

 liquid sweets are more secure. Bees sometimes make comb of 

 irregular shape; to prevent this the Swiss use an artificial guide, 

 consisting of a thin plate of wax about two or three inches square, 

 indented all over with hexagonal depressions, which is attached to 

 the inside of the box for storing honey. Experience proves that 

 bees will make more honey when supplied with these cell-com- 

 mencements than when they are left to take the initiatory steps 

 for the foundation of their wax building. 



Cause of the Breaking of Car- Axles. 



The Paris Cosmos, of December 19, states that Mr. Wedding, a 

 manufacturer of engines in Berlin, has lately attacked the opinion 

 that the rupture of car-axles is due to a crystaline condition ob- 

 tained by the iron by continuous vibration. His first doubt arose 

 on examining a broken iron beam in his own establishment, which 

 had not been exposed to the least vibration, yet showed a crystal- 

 ine structure like the broken car-axles. He verified his doubt by 

 experiments, and supported an axle in the center and at one ex- 

 tremity, then suspended at the other extremity a very heavy 

 weight, so that the fibers of the iron in the upper part were 

 expanded, and in the lower part were compressed; afterward 

 the axle was turned, half-way around on its axis, so that the parts 

 first compressed were expanded, and those first expanded were 

 compressed. He again turned the axle half around, and continued 

 this vice versa operation until the axle broke, which happened in 

 about four hours. The fractures showed different kinds of mole- 

 cular structure according to the quality of the iron used. Sam- 

 ples of these fractures were exhibited at a meeting of Prussian 

 technologists, and the opinion was expressed that if iron really 

 underwent such molecular changes, by means of vibration, as had 

 been supposed, its use would be very dangerous for many pur- 

 poses, and the conclusion arrived at was that if a fracture shows 

 crystaline structure, and want of cohesion, the iron was bad from 

 the beginning. 



We must add that the opinion expressed by the principal Ame- 

 rican iron manufacturers is, that good wrought iron is perfectly 

 reliable, and will never become crystaline or brittle. 



