96 
ROBEKT JAMES KELLOGG 
the principle of form B of the sonoscope in figure 2. This form 
of the sonograph principle would seem to be more sure of success, 
since the tiny tube mirror Mi could deal with and magnify very 
small divergences in the paths RR and RR', and probably need 
not be as far from 00 as would be necessary for the lens L 2 in 
form A. 
In form C (fig. 6), a simple concave lens is substituted for the 
battery of mirrors or lenses of forms A and B. Otherwise it is 
the same in principle as form B. The difficulty of length be- 
tween the prism Pvi and the lens L 2 would probably be much 
greater in this form than in form A. Perhaps it could be partly 
overcome by using an additonal concave lens between L 2 and Fi. 
Whether or not the above suggestions prove to be practicable, 
the problem of approximating a perfect graphic record of sound 
vibrations must fulfil the conditions of eliminating all distortion, 
suppression, extraneous addition, reinforcement and muffling. 
In the final solution the light lever (or some electrical, magnetic 
or x-ray substitute) will probably enter. If a receiver horn and 
diaphragm enter in, the form must be so shaped as to have the 
widest range of equalized responsiveness to all forms of vibra- 
tions, and the diaphragm must be of such form and texture or so 
weighted as to avoid all self-vibration and unequal responsive- 
ness. Perhaps the outer ear and ear drum of man or other 
animals still have suggestions to give us on these lines. If 
physically vibrating parts enter in, they must be .of the minute 
order of magnitude or vibrative amplitude which allow them to 
vibrate fully and freely on the scale of normal sound- vibrations, 
and so damped or adjusted as to eliminate muffling, reinforce- 
ment and self-vibration. Mechanical construction (if any 
remains) must be practically perfect. Probably the final solu- 
tion will come along the line of some principle which (like the 
sonograph principle suggested above) uses a light-lever whose 
initial deflection is effected by refraction as it passes through 
free sound-transmitting air. 
