394 APPLIED SCIENCE 



is a block of iron ground to a sharp or chisel edge. Various 

 shaped anvil blocks and hand-hammers, which may be classed 

 as special tools, are also used. Tongs for holding the iron 

 are made in a wide variety of shapes and sizes. 



442. Lighting the Blacksmith's Fire. To fire a forge, all 

 clinkers are first removed and some inflammable material, 

 such as wood shavings or oil waste, is selected and placed on 

 the hearth over the tuyere. The fuel should be the best 

 quality soft coal thoroughly moistened, so that it will coke or 

 stick together when heated. Coal containing hard spots will 

 cause an uneven fire. The fuel is carefully placed around and 

 over the ignitible material, leaving one opening on the top 

 for the draught, and one in front for the placing of the metal to 

 be heated. After the material is ignited the proper draught is 

 applied until the coal catches. The fire is shaken occasionally 

 in order to maintain a live and even heat. If this is not done, 

 the interior burns out, leaving a hollow space which is worth- 

 less for heating. When necessary the fire is banked by cover- 

 ing it with fine, damp coal. 



443. Scarfing and Welding. The two principal opera- 

 tions performed by a blacksmith are scarfing and welding. 

 The process of scarfing consists of flattening the edges of two 

 pieces of iron preparatory to welding, so that when the edges 

 overlap they are of the same thickness at the junction of the 

 two pieces as the rest of the iron. Care should be exercised 

 in performing this operation, as the class of weld depends 

 almost entirely upon the nature of the scarf. Scarfing is not, 

 however, necessarily preparatory to all welding. For in- 

 stance, in the butt weld, the two pieces to be welded are 

 simply abutted together, sometimes in the fire. 



