involved in the Construction of Artillery. 



393 



Prof. Hodgkinson with long bars ; and amongst the results of this class, I find almost the 

 only trials of the crushing force for steel tliat I have met, thus r — 



Cast-steel, not hardened, .... 198,944 lbs. per squaru inch. 

 ,, hardened low temper, . 354,554 „ 



„ hardened mean temper, . 391,985 ,, 



„ hardened highest temper, 372,598 ,, 



It seems scarcely credible that no series of experiments appears ever to have been made 

 by physicists or artillerists hitherto, upon the compressive force for bronze ; at least I have 

 searched for such in vain. Its importance, as one of the data for calculation, has been 

 pointed out in the text. 



Some experiments are subjoined, for which I am indebted to the kindness of Colonel 

 E. F.Wilmot, R. A., Superintendent of Gun Factories, Woolwich Arsenal, who obligingly 

 had them recently made, at my request. 



The series No. 4, appears to be of a character to use in practice ; the others, though nut 

 applicable so directly, are not devoid of practical interest. 



Experiments made at the Royal Gun Factory, Woolwich Arsenal, on the Resistance of Bronze 

 Gun Metal to Compression, April, 1856: — 



• This trial was repeated several times, with the same result. 



t The results of this experiment, being made of metal more homogeueous, are perhaps the most correct ; hut it is 

 tlesirable to use larger .-jpecimeiis. 



