:326 RECORDS. 



more convenient than smoked paper or siphon pens for time 

 records, such as rhythms, conflict of the visual fields, after- 

 images, etc. 



2. Instruments were shown by which a number of faint clicks 

 could be given at intervals of a second for testing sharpness of 

 hearing and defective hearing. Instead of giving the observer a 

 continuous sound, such as from the ticking of a watch, two, 

 three, four or five faint sounds are made, and the observer is 

 asked how many he hears. By this method errors from the 

 common illusion in the case of faint sounds are avoided. 



3. A method was exhibited for testing color blindness by the 

 time it takes to distinguish one color from another. By the 

 normal individual red can be distinguished from green in about 

 the same time as blue from yellow, but it takes longer to distin- 

 guish red from orange. If the observer belongs to the red-green 

 class of the color blind, he can distinguish blue from yellow as 

 quickly as others, but not red from green. An instrument was 

 shown by which the conditions of the railway service can be 

 imitated, it here being necessary first to distinguish a certain 

 color and then to make the proper movement. 



The aim of the investigation upon which Mr. Henmon's paper 

 is based is to measure qualitative differences in color by the 

 time of perception. The colors taken as standards were red, 

 orange and yellow, whose wave-lengths had been definitely 

 determined. Equal intermediate steps between orange and red 

 were produced by the mixture of pigments. Small squares of 

 each of these colors, 3x3 cm., were mounted on cards side 

 by side with red, and exposed to the subject by means of a 

 drop-screen so arranged as to give almost instantaneous 

 exposure. The subject reacts with the right or left hand 

 according as the predetermined stimulus appears to the right or 

 left. The registration is made with the Hipp chronoscope. 

 The results of 6,000 reactions gave evidence of the validity of 

 the method and the fruitfulness of the problem. Equal objec- 

 tive differences are correlated with differences for consciousness, 

 showing a definite increase as the magnitude of difference is 

 'decreased. 



