94 



Copy of a Letter from Messrs. R. and W. Hawthorn, 

 Engineers, Newcastle-upon-Tyne, to Graham and Co., 

 dated November 29th, 1842 :— - 



Gentlemen, — We beg to hand you the result of some experi- 

 ments as to the changes produced in the strength of wrought iron 

 in the process of manufacture into the various articles required by 

 engineers ; and, as part of the iron used is of your own make, we 

 trust that these trials (from the suggestion of Jas. Nasmyth, Esq., 

 in a highly valuable article published in the September Number of 

 the Engineer and Architect's Journal, on the tenacity of wrought 

 iron,) will not be altogether unacceptable to you. 



Experiment \st, — Hot 

 blast railway axle from 

 Milton Iron Works, one 

 journal end heated red and hammered till cold, diameter of journal 

 of an inch ; 6 blows fractured it, 3 blows more broke it clean 

 off ; fracture | crystalized, \ fine fibrous iron. 



Experiment 2nd — The other end of the same axle, heated red 

 and hammered till cold, then heated red and allowed to cool gra- 

 dually ; 1 00 blows bent it about three inches without the slightest 

 appearance of fracture. 



Experiment 3rd. — Hot blast If inch square bar from Milton 

 Iron Works, heated red and hammered till cold; reduced to 1^ 

 inches square, laid 4 inches over the anvil : 

 10 blows bent it 1 inch.' 



20 „ „ 



30 ,, 2 „ 



40 „ „ 21 „ 



Not the slightest appearance 

 of fracture. 



Experiment Ath. — The same bar, after receiving the above 50 

 blows, was turned over and nicked in the inside of the bend ; 4 

 blows fractured, and 2 more blows broke it clean off ; § fine fibrous 

 iron, I crystalized, resembling steel. 



Experiment 6th. — Cold blast scrap-iron bar from Messrs. Haw- 

 thorn's stock ; bar 1 i inches square ; heated red and hammered 

 till cold, reduced to If inch square : 



6 blows fractured it partly through. 

 10 „ more bent it 1| inches. 

 10 J, „ 2|| „ Fracture I through. 



