478 Dr. W. R. Jack. On the Analysis of Voluntary [Mar. 21, 



velocity of the more complicated movements could be increased to 

 some extent by practice. Only a few preliminary tracings, to accus- 

 tom the hand to the instrument, were therefore allowed to each sub- 

 ject, in order that all might be as much as possible on the same 

 footing. Full details of the velocities attained in each case, and 

 figures of the apparatus used, are given in the original essay. In 

 this abstract only a statement of the results attained will be made. 



It is not contended that the figures there given represent the 

 absolute velocities of the movements made, for the retarding influ- 

 ence of friction on the slide has to be allowed for, and the increase 

 in the space travelled over through the extension of the needle beyond 

 the end of the fingers. But, as all the subjects were under the same 

 conditions, a comparative estimate of the velocities may be arrived at. 



Beginning with the influence of training upon the velocity of the 

 movements, the pen-movement was first studied, and the rate at 

 which a distance of 3 cm. in the middle of the slide was traversed 

 was taken as the standard of comparison. Unfortunately no tracings 

 of this movement were taken from musicians, but, on comparing the 

 average of the tracings derived from those of average and those of 

 inferior manual education, the following conclusions were arrived at. 



(1.) That in those of inferior manual education (whose two hands 

 were both untrained) the velocity is equal in both hands (3'4"/H7 for 

 the right and 3'5"/117 for the left hand). 



(2.) That in those of average manual education the velocity is 

 greater in the right hand, which has been trained (as in writing) 

 than in the left, which has not (2 9"/117 for the right and 3'6"/117 

 for the left hand), an exception being found in the case of the author, 

 both of whose hands had been pretty equally trained, in which case 

 both had the same velocity (3" /1 17). 



(3.) That the velocity is greater in the right hand of those of 

 average education than in the right hand of those of inferior educa- 

 tion. 



(4.) That the velocity in the left hand (which has been little 

 trained) of those of average education is practically identical with 

 that in the left hand of those of inferior education. 



The velocity of contraction of a single finger was next examined 

 with the follow ing results : 



(1.) That the velocity is equal, or nearly so (2"/117) in the first 

 and second fingers, and is greater than that in the third and fourth, 

 which have also a nearly equal velocity. This may be due to the 

 special arrangement of the tendon of the extensor communis digito- 

 rum for the third finger, and for the fourth to the awkward position 

 in which it was placed. 



(2.) The velocity of each finger is practically identical for the two 

 hands. 



