54 IOWA ACADEMY OF SCIENCE Vol. XXV, 1918 



the equation and the experimental values is good in each of the 

 nine cases. It will !» noted that the slope changes with m alone. 

 The data are assembled in Table I. How nearly the linear 

 relation appears to hold is seen from the column of values of the 

 constant, (f+nB)/N, which is equal to m the slope, and is de- 

 rived from the experimental values. The extremely slight varia- 

 tion is regarded as entirely due to observational error, which 

 increases witli f. 



CONCLUSION. 



Secondaiy regions of stroboseopic response present during a 

 reading on the tonoscope, particularly when a fork is used, are 

 thus seen to be in accord with the demands, of equation (1), or 

 its special form (4), rather than due to harmonics. That is, a 

 pure tone will produce secondary responses in addition to a 

 primary response. By "primary response" is here meant the 

 region of rows of dots in response containing the stationary, or 

 nearly stationary row that is being read, which region has one 

 of the values of n/m already mentioned for voice pitch readings 

 on the tonoscope. However, there appears to be nothing to 

 prevent a hannonic from producing its own primaiy and second- 

 ary regions of stroboseopic response, provided either that it has 

 sufficient energy itself to actuate the manometrie flame, or other 

 device for changing the frequency of the sounded tone into 

 luminous frequency, or that such device possesses on its part 

 unlimited sensitiveness to sound vibrations. Mathematically, 

 at least, the condition exists of a fundamental producing a 

 primary (term restricted here to n/ni=l) and an unlimited 

 number of secondary stroboseopic responses, and each one of all 

 its possible harmonics simultaneously doing the same thing. 



In conclusion of this paper, thanks are due Dean C. E. Sea- 

 shore, head of the Department of Psychology at the State Univer 

 sity. for his kind permission to make this experimental test of 

 tlie stroboseopic velocity equation with the tonoscope, and for 

 use of forks belonging to that department. 



