ON THE DISEASES OF THE TEETH OF THE HORSE. 63 J 
is necessary sometimes to replace the balling-iron after having 
brought the head into this position, as often the portion of the 
tooth will be forcibly retained between the other molars, but 
which will be effectually separated by a second application of 
the iron. Having removed the piece, the head may again be 
elevated, and any irregularly fractured edges levelled by means 
of the flat rasp. 
It cannot be expected that all the irregularities we meet with 
in the teeth can be overcome with one kind of instrument, as, 
owing to the peculiarities of situation and of growth, no one 
tool could always be brought to bear; therefore, I have in- 
vented another instrument, to which I now beg leave to direct 
your attention It is an instrument which, you perceive, is 
rather longer in the handle than the former one. It consists of 
a solid or entire piece of steel. At one end is the handle, which 
is encased on either side with pieces of wood, retained in their 
situation by rivets. The other end is shaped into a hookdike 
form, flattened and bevelled, with a guard on one side, for the 
purpose' of retaining the instrument in its situation, and pre- 
venting its being displaced from the tooth. It possesses some 
of the advantages of the former sliding chisel : but this instru- 
ment is not meant to be used by itself ; it is intended to pre- 
vent the concussion on the jaw, while the operator, with a 
chisel, strikes off any projecting angle of the tooth. The chisel 
I have employed is like the one I now exhibit, the GUARDED 
Chisel ( see Jig. 4), which is of sufficient width or space to 
cover the table or upper surface of the molars. For the pur- 
pose of enabling it to pass readily over the teeth, without 
danger of its being dislodged by the motion, I have caused two 
guards to be made, by having a portion of the steel turned 
down on either side, in the form of lips. These effectually 
prevent the instrument from being thrown off the teeth during 
an operation, or by any struggles that might ensue when the 
blow is given, thereby anticipating even the possibility of 
injury to the mouth. 
As I feel I shall be getting into difficulties in my description 
for want of names to carry me on, and being at a loss for a 
better term, I have designated the first of these instruments a 
Lateral Repeller ( see Jig 3). It is necessary for me to 
make this distinction, as I intend explaining to you the use of 
another instrument which bears some resemblance to the one I 
have just laid down, and which possesses some advantages in 
its construction, inasmuch as it can be used when the other 
could not be ( see Jig 5). You perceive in the handle and shaft 
it is like the lateral repeller, but at t lie operating end it is 
turned down or necked; while on either edge it is bevelled 
