OPEBATIONS ON THE TEETH. 99 



the blow or force necessary to be given. When we desire 

 that it should cut through the hard and solid tooth of the 

 horse, it will be seen that the rod of the chisel, working 

 through the cylinder, would fall from any situation in which 

 it might be adjusted, on account of the elevated and standing 

 position in which the animal's head would necessarily be 

 held by the operator. To guard against the chisel slipping 

 backwards, and to render it steady, but not fixed, I have at- 

 tached, as you will perceive, at this end of the cylinder a brass 

 bulb, which gives to the handhold of the operator more secu- 

 rity. The inside of the brass bulb, first mentioned, is hol- 

 low, so as to allow of some packing being placed within; 

 when pressing upon the rod of the chisel, it acts on the same 

 principle as it does in the piston box of a steam engine. To 

 make this more clear, the brass bulb is screwed down upon 

 the cylinder, thereby causing the packing to be so compressed 

 as to retain the rod of the chisel in its desired situation. 

 The mode of operating with this instrument will require 

 some explanation from me, for I have been asked by some 

 gentlemen whether the chisel is to be drawn back to the 

 utmost range of the guard? I mention this that others may 

 not fall into the same error; for if it were so placed before 

 the chisel reached the tooth, the force of the blow would be 

 expended to a great extent, on account of the distance it would 

 nave to travel, and the resistance it would naturally have to 

 overcome. For these reasons we should probably be foiled 

 in the performance of that which we were desirous of accom- 

 plishing, and the tooth would in all likelihood, remain entire. 

 " A balling-iron being placed in the mouth, and retained 

 in its situation by an assistant, the chisel is to be drawn 

 sufficiently back through the cylinder to allow the frame to 

 be placed over the tooth, surrounding that portion we are 

 desirous of removing. This will be better accomplished by 



