136 ANIMAL DENTISTRY. 



on the market, some simple and others complex, which hold 

 the blade solid by various means. Some are equipped with a 

 mechanism by which the head can be placed at different 

 angles with the aim of combining two instruments in one, i. 

 e., the straight and the angular float. All these inventions 

 to date are but poor imitations of the old reliable simple 

 screw-head float, and are neither durable nor practical, and 

 few will hold the blade as solid as the old pattern. 



These instruments are generally designated as the House 

 floats ; they have been in use for more than thirty years, and 

 as they offer but little chance for improvement they will 

 probably always retain the prestige of being the most satis- 



FiG. 89a. 

 Straight and Angular Floats, with Lines showing the Proper Angle of 



Each. 



factory instrument of their kind. Two styles are recom- 

 mended — the straight float and the angular float. 



The Straight Float is used to file the lower arcades 

 and the posterior two-thirds of the superior arcades, and to 

 facilitate its passage to the remotest teeth its head must be 

 on a straight line with the handle, i. e., when the handle lies 

 flat upon a plane the head, — face downward, — must do like- 

 wise throughout its entire length. The posterior end of the 

 arcades, especially the inferior, cannot be reached with a 

 float of any other shape without opening the horses's mouth 

 wide enough to provoke resistance. 



The Angular Float is used to file the anterior third or 

 half of the superior arcades, which, owing to the inward cur- 



