A NEW OPERATING CHAIR. 71 



The back may be moved 



Forwards, 



Backwards, 



Upwards, and 



Downwards. 

 The headpiece may be moved 



Backwards, and 



Forwards. 



The combined movements of all or any two of the 

 parts may also be enumerated among the effective 

 adjustments. It is not proposed to give any minute 

 description of the particular uses to which the 

 various movements of the chair can be made sub- 

 servient, believing that they will for the most part 

 suggest themselves to those who may be desirous of 

 adopting this or any similar principle of construc- 

 tion. 



Ofy first, the Seat-movement. — The seat (indepen- 

 dent of the back) can be raised nine inches from the 

 ordinary height of a chair by a few movements of 

 the foot upon the pedal placed at the bottom of the 

 chair. Thus, whether the patient be under four 

 feet in height or above six feet, the head can be 

 brought to the same level for operating. When the 

 upper teeth are to be operated upon the head of the 

 patient is required to be upon a higher level than 

 when the lower teeth have to be treated. This 

 change can be effected by the seat-movement. 



Of the Second, or Back-movement. — By the back- 

 ward or forward movement any required angle of 

 inclination may be given, from the upright to a 

 position almost horizontal with the seat. This is 



