-feature's trades. 



high (or half the height when it shall be com- 

 pleted). A trough, about twenty or twenty- 

 one inches wide and half as deep, is scooped 

 out the whole length of the pulverized stuff, 

 and in this is placed what has before been re- 

 ferred to as the core of the furnace, namely, 

 pure coke broken into small pieces, but not 

 pulverized, as in the case of the other mixture. 

 The amount used is carefully weighed, so as 

 to have the core the proper size that experi- 

 ment has proved to give the best results. The 

 core is filled in and rounded over till it is in 

 circular form, being about twenty-one inches 

 in diameter. At each end of the furnace the 

 cure connects with a number of carbon rods 

 about sixty in all that are thirty inches long 

 ami three inches in diameter. These carbon 

 rods are connected with a solid iron frame that 

 stands flush with the outer end of the fur- 

 nace. On the insi.lr tin- spaces between the 

 rods are packed full of graphite, which is 

 simply carbon or coke with all the impurities 

 driven out, so as to make good electrical con- 

 nections with the core. This core corresponds, 

 electrically speaking, to the filament in an or- 

 dinary incandescent lamp, only it is fourteen 

 feet long and twenty-one inches in diameter. 

 The mixed material is now piled up over this 

 core, and the walls at the sides are built up 

 until the whole structure stands about eight 

 feet from the floor a mass of the fine pulver- 



