24 



points of the compasses were ten, fifteen, or even twenty centi- 

 metres apart ; whilst on the other leg he could distinguish them 

 at a distance of twelve centimetres. The normal limit is gene- 

 rally, for that limb, from three to five centimetres. In another 

 case where anaesthesia was slighter, the limit of the discriminat- 

 ing power was at from nine to sixteen centimetres. In two other 

 cases, in which the diminution of sensibility had not been found 

 by the other means of diagnosis, the compass indicated a 

 very slight and beginning anaesthesia. The limit was at from 

 six to seven centimetres. 



These facts, and many others, have demonstrated to me that by 

 the help of the compass, a physician can ascertain : 1st. Whether 

 there is a slight anaesthesia or no. 2d. What is the degree of 

 anaesthesia. 3d. What changes occur every day in the amount 

 of anaesthesia. 



The same is true for the cases of hyperaesthesia. In a case of 

 paraplegia of the motor power, the patient felt the two points of 

 the compasses, on his feet, even at the distance of five millime- 

 tres, whilst a healthy person feels the two points only when they 

 are at a greater distance than twenty-five millimetres. 



I shall add, that for succeeding in such experiments the two 

 points must be blunted and applied simultaneously.* 



* See Gaz. Med. de Paris, 1849, t. iv. p. 1012. 



