-344 Prof. Barton and Miss Browning on a Syntonic 



broken together, are then closely like those current as 

 representing colour sensations. 



It may be well to note here the flexibility of the present 

 hypothesis of syntonic vibrators of three frequencies. The 

 frequency of each responder and its damping are entirely at 

 -our disposal ; thus giving six variables which may be chosen 

 to accord as closely as possible with experimental facts. 



It should be remarked that the full line curves give 

 amplitudes of the responding vibrations postulated. Their 

 intensities would be proportional to the square of the ampli- 

 tude multiplied by the square of the frequency. Conse- 

 quently, curves of intensity would be much more sharply 

 peake I and exhibit some asymmetry. 



Any further details as to the possible mechanism of such 

 syntonic responders or that of the subsequent physiological 

 changes we do not presume to enter upon. 



5. Experimental Arrangements. 



Among the facts of vision already enumerated, the early 

 ones show that the range of the responders should be slightly 

 within an octave, and that their relative frequencies should 

 correspond to those of red, green, and violet. Further, to 

 leave no gaps in the visual spectrum necessitates considerable 

 damping in the responders in order that their "resonance" 

 should be sufficiently spread. 



Fig. 2. 



Experimental Arrangement. 



The mathematical theory of forced vibrations holds for 

 almost any type of syntonic responder. Hence we here 

 adopt as an experimental test and illustration of the hypo- 

 thesis the simplest mechanical vibrator. The arrangement 

 consists essentially of pendulums hanging from an overhead 

 cord, as shown in fig. 2. 



A stout horizontal cord ACB has a pendulum with heavy 



