METHOD OF SAWING CAST IKON, 271 



V. 



Extract from a Letter addressed to Mr. d'Arcet ly Mr. Du- 

 FAUD, Director of the Iron IVbrhs at Montalaire, near Creil*. 



SIR, 



I HAVE undertaken, with the greatest pleasure, the expe- Sawing heated 

 riments on sawing hot cast iron, that you recommended to '^ggfg^*^'^ ^^^' 

 me: I have followed your instructions 5 my trials have been 

 attended with the most complete success, and I hasten to give 

 you an account of them. 



These experiments were the more interesting to me, as I 

 have since applied them to practical purposes. 



My first trial was made with the support of a grate, 108 mil. Experiment. 

 [425 in.] thick. This piece of cast iron was heated in a forge 

 fire with coal : and as soon as it had acquired a sufficient de- 

 gree of incandescence [this is the French term] it was placed 

 on an anvil, and I sawed it with a common carpenter's saw, 

 without any difficulty, and without any injury to the saw, 

 which I dipped immediately into cold water". The carpenter 

 continued to work with the same saw, without having any 

 occasion to repair it. 



In this my first trial a little accident occurred. The end of The iron 

 the iron I was sawing off not being supported, it broke, when ^°^\l h^^e^^ 

 20 or 25 m. (about a line) remained to be cut through 3 but done, for want 

 this slight defect I immediately removed with the saw. Con- °^ support at 

 vinced of the ease with which a common saw would cut hot 

 cast iron, I afterward applied it to the demands of the iron- 

 works. 



I had occasion to shorten a pivot of 135 m. [5*3 in.] in dia- second expcri- 

 meter ; but, afraid of its breaking if I cut it cold, an operation ment. 

 besides very tedious and uncertain, unless executed in a lathe, 

 I had resolved to cast another, when the experiment I have 

 just mentioned determined me to saw it. 



Having marked the place of section with red lead, I placed 

 the pivot in a reverberatory furnace ; and when I thought it 

 sufficiently hot, I had it taken out of the furnace, and placed 

 on an iron support, so that the two ends had equal bearings. 



* Aan. de Chim. vol LXXXII, p. 218. 



In 



