A NEW OPERATING CHAIR. 73 



withdrawing pressure from the pin the head-piece 

 again becomes fixed in any position required. 



The centre of the shaft upon which the head- 

 piece rests, being curved from the axes upon which 

 it revolves, an eccentric motion is produced, by which 

 an additional height of three inches can be instantly 

 given, to suit the tall patient, without the necessity 

 for raising the back of the chair or lowering the 

 seat. 



When the posterior surface of the upper molars 

 requires examination, the head of the patient may 

 be brought to recline at almost a right angle with 

 the body, thus enabling the light to fall directly 

 upon the part. The head being in this position, 

 the saliva will gravitate towards the back of the 

 mouth, and the operation will consequently be less 

 impeded. 



In extracting a tooth from the superior maxilla the 

 advantage of this position of the head is obvious, 

 the operator being enabled to economize his force 

 by applying what he has to the greatest advantage, 

 at the same time the eye is enabled with extreme 

 facility to follow the movements of the instrument. 



In submitting this plan of an operating chair to 

 the Society, I am conscious that it will not meet 

 the requirements of every operator ; each one neces- 

 sarily has his own ideas respecting the position in 

 which the patient should be placed, but the great 

 assistance which this chair has afforded me, by 

 lessening the fatigue and inconvenience experienced 



