356 PHYSICAL EXPRESSION. 



together, and will enumerate how many times this 

 special combination of movements has occurred. 



This apparatus has been used, and results have 

 been obtained, but the labour of obtaining results 

 is very great. During the last year I have been 

 endeavouring to make the apparatus more complete 

 and more serviceable. I am replacing all electrical 

 apparatus by pneumatic mechanism, as being 

 simpler ; numerous causes of delay have arisen, but 

 when the whole is completed a full account will 

 be published. Experiments are arranged for 

 recording the movements of the eyes, head, and 

 fontanelle, but they are not completed. As to the 

 uses of this means of investigating the nerve- 

 centres, I will state the propositions and problems, 

 and say how I propose to follow out such inquiries. 



As to the problems, and how to work at them. 



In each case, for the sake of simplicity, we will 

 suppose hand movements, and the nerve-centres 

 causing them, to be the subjects of inquiry. 



(1) In exhaustion, finger twitching is some- 

 times an expression of the condition. Here the 

 number of finger twitchings in a given period of 

 time, say one hour, may be counted; we can 

 enumerate the frequency with which each separate 

 finger has moved, and also the frequency with 

 which any combination of fingers twitched to- 

 gether. The external circumstances may be varied ; 

 say the enumerations are taken for half an hour 

 while the subject is alone and unoccupied, then 

 during half an hour while he is engaged in con- 



