2/2 METHOD OF SAWING CAST IRON. 



In four minutes, with two saws, which I used and cooled alter- 

 nately, the piece was cut off, to the great astonishment of my 

 workmen, who found the saws unhurt. 

 Third experi- The same day I performed a still more difficult operation. 

 I had an anvil, which I was about to cast afresli, because it was 

 41 m. Ll'6 in.] too thick, so that it could not be placed in its 

 bed. 



I marked the place of the saw kerf with red lead. The 

 two cuts to be made were 217 m. [8 5 in.] long, by 18g m. 

 [7'4 in ] high j and the thinness of the piece to be cut off re- 

 quired precision. This anvil was heated in a reverberatory 

 furnace, in the same manner as the pivot ; and, when suffi- 

 ciently hot, two workmen took hold of it with a strong pair of 

 tongs, and laid it on a block of cast iron. It was cut with 

 much ease and precision by the same saws that had been used 

 in the preceding instance. 

 General re- In the course of these experiments I remarked, 



^^'■'^*- 1, That hot cast iron may be sawed as easily, and in the 



same space of time, as dry wood. 

 ^ 2, That, to diminish the resistance, the saw should be set 



fine. 



3, That iron heated in a furnace saws more easily than if 

 heated in a forge : and the reason is simple j in a furnace it is 

 heated equally throughout, while in a forge the part near the 

 tewel is almost in a state of fusion, while that opposite to it is 

 scarcely red-hot. 



4, That the iron mXist not be made too hot ; for, if its surface 

 be too near a state of fusion, the saw will be clogged, and th« 

 process will not go on well, 



5, That the saw should be moved very quickly, because then 

 it will be less heated, make its way better, and the cut will be 

 more clean and exact. 



6, Lastly, that the iron should be so placed as to have a firm 

 bearing every where, except where the saw is to pass, otherwise 

 it is liable to break before the cutting is finished. 



1 These, Sir, are the whole of my experiments and observa- 



tions ; and I shall be well pleased if they answer your views. 

 The practice ^^ '''' ^^^ niore to be wished, that this method of cutting cast 

 may be of ex- iron should be rendered as public as possible, as it may be hap- 

 pily 



