158 T. O. Mendenhall on the Sensorium. : 
blow upon the head, face or hand, as I might desire. The 
of the instrument which came in contact with the skin consisted 
example following, that it required less ti 
the blow was received upon the forehead than when it was t& 
than usual; that in his occupation—that of a chemist—he cor 
tinually used it as a means of testing the fineness of powders 
With different persons as many as two thousand individual 
trials have been made and the errors of experiment eliminated; 
as far as possible, by the method of averages. I give below? 
table of the reduced results in one case, in which each number 
is the mean of the results of from forty to eighty trials. As 
was anticipated, different individuals furnished in some case 
strikingly different results, but with the one exception give? 
above, they all followed, I believe, the order of the following 
