158 Wisconsin Academy of Sciences, Arts, and Letters. 



varying from to 19°. Others were allowed to remain 

 throughout the cold of last winter, 1872 and 1873, exposed to 

 a temperature of about 20° in the open air. The bars were 

 broken, both in their cold state and after raising the tempera- 

 ture above 0. In no case was there any appearance of crystal- 

 lization. Mr. Caron attributes the breaking of rails in winter 

 to the greater shock to which they are subjected on tLe frozen 

 ground and to inferior qualities of iron. 



Should the publication from which I took my information 

 be correct, neither Doctor Joule nor Mr. Spence have proven 

 anything which I did not consider a fact, viz : that the speci- 

 mens tested by the former were stronger at 12° Fah., than at 

 50°, or that the difference were uncertain, and that those tested 

 by the latter showed as great, or a still greater difference than 

 8^ per cent, existed in bars of cast iron of 1-2 inch square. There 

 is no doubt that a great many fractures of rails and axles occur 

 from the faulty nature of the iron, but these occur at all seasons, 

 and, as a general thing, it is difficult after a railway accident to 

 say what broke first. All that I could discern in several cases 

 was an indescribable wreck. 



From my experience with various kinds of implements and 

 machinery, I have every reason to believe that iron and steel 

 become stronger under a moderate degree of frost to a steady 

 strain, but that from a very moderate to an extreme degree of 

 frost they are exceedingly more susceptible of fracture from 

 impact than when not frozen. The latter is well known to 

 every mechanic who endeavors in every way to guard against 

 the results. I had hoped to make some experiments, and 

 made some preparation for the purpose, but found that I 

 would not be able to produce the same in time for the present 

 meeting of the Academy. I will conclude by noticing a few 

 special cases of application. The entire weight of a structure, 

 such as a bridge or roof, together with its passive or accidental 

 load, is borne by the points resting upon the walls or abut- 

 ments, and the plates and bolsters, if of wood, receive the en- 



