A NEW TONOSCOPE 205 



The sources of a child's information regarding musical in- 

 tervals are his listening to a piano or other musical instrument, 

 or his hearing the intervals sounded by almosl anyone who may 

 be at hand to do this for his benefit. The chief difficulty with 

 the first method is that the instrument may be and generally 

 is, to an extent at least, out of tune, and in the second case the 

 fidelity to pitch of the older person who is sounding the inter- 

 vals is more or less questionable, depending both upon how good 

 a musician this person is and also upon his physical condition, 

 which has a marked effect upon one's fidelity to pitch. 



A child's first impression is the important impression. In the 

 interest of making his first impressions regarding matters of 

 pitch in singing as nearly absolutely correct as possible an in- 

 strument like the tonoscope should be made readily available to 

 the public. In fact it should be an instrument available in 

 the home itself. Availability includes as small size and weight 

 as possible together with low cost. 



The idea of improving the tonoscope in at least these respects 

 has continued with the author since the series of tests to which 

 reference has been made. In February of the present year 

 (1916) experimental work was undertaken with a view to sim- 

 plifying the instrument. This resulted in a new method of 

 producing the stroboscopic effect which is particularly adapted 

 to the tonoscope because it does away with the manometric 

 flame and its necessary gas supply. It also permits the illum- 

 ination to come from one end of the drum rather than directly 

 in front of it. The new method is presented in a separate paper. 



It was also found by stroboscopic tesis that a mechanical 

 clockwork meter of the phonograph type possesses a marked 

 constancy of motion, which over an interval of aboul two min- 

 utes is constant to within one-tenth vibration per second. By 

 introducing an electric wind to keep the spring automatically 

 at the same tension very great constancy can be secured and 

 thus the special synchronous motor for constant speed rendered 

 unnecessary. Also it was found that the stroboscopic drum 

 could be greatly reduced in size, and both drum and scale placed 

 at the distance of most distinct vision from the eyes, 



Thus there has resulted an improved tonoscope that has the 

 desirable qualities of portability and reduced cost of manufac- 

 ture. It is an instrument easily available to the home and the 



