166 



WINTER SHOEING. 



The slight burr produced on the upper surface of the shoe 

 by the passage of the drift should always be removed with a 

 file, and never beaten down with the hammer. The first hole 

 is widened by using a drift. In this process the heels of the 

 shoe are warmed to a dull red, and the drift driven through at 

 right angles to the surface by a few light rapid strokes. 



A simple method of manufacturing cogs was invented by 

 a veterinary surgeon named Schleinitz. The blunt cogs are 

 made cold, the chisel- edged warm. In forming a blunt cog the 

 end of the square rod is hammered on all sides until it will 



a 



Fig. 138.— a, upper; «', lower end of anvil for forming shank ; b, anvil for forming head. 



enter the mould (fig. 138, a) to within about one-twentieth of 

 an inch of the end, when it is cut off with the ordinary cutter. 

 Chisel-edged cogs are similarly fitted and sharpened and cut off 

 on a special anvil (fig. 138, h). They can then immediately be 

 hardened. The thickness of the drift at its widest part corre- 

 sponds to the greatest width of the mould. One man can thus 

 make cogs without assistance. 



As compared with screws, cogs have certain advantages, 

 viz. : — 1. They never break off. 2. Their manufacture and 

 use are simpler. 3. Being so cheap, everyone can keep a few 

 in stock and affix them without special help. 



