FOR REDUCING IRREGULARITY. 221 



piece of gold plate, and over the plate a liga- 

 ture, passing throngli holes on either side of the 

 recess. The ligature is then made fast over the 

 tooth, on which the expanding wood now acts. 

 The bone may be left sufficiently deep to prevent 

 the antagonistic teeth from being obstructive, and 

 at the same time mastication is but little impeded, 

 and the incumbrance to the mouth is much less 

 than when spiral springs are used, and more con- 

 venient and less unsightly than when gold bars 

 are brought in front of the teeth. 



Wood compressed in the above way will be 

 found most useful in dividing the teeth ; a very 

 thin shaving placed between two teeth may in a 

 very few hours be made to produce a division 

 equal to the sixteenth of an inch. 



Lately, the use of vulcanite for forming the 

 plate has been most successfully used. The com- 

 pressed wood, on Mr. Harrison's plan, can be 

 placed in it very readily, or it can be used for 

 carrying ligatures or elastic bands. Its perfect 

 fitting has very great advantages in enabling the 

 plate to keep its position, and remain firm without 

 the use of ligatures, and for the counteracting 

 pressure which is distributed so equally over the 

 other parts of the mouth. 



We are sometimes obliged, in order to keep an 

 instrument secure in the mouth, to make use of 

 ligatures. For that purpose I have found the 

 fine, hand-spun, hempen thread, in many cases 



