224 



AUSTIN: MUSICAL RECEPTION 



the teeth at a frequency a Httle greater or less than the frequency 

 of the appHed voltage. Under these conditions an alternating 

 current will flow in the telephones of a frequency equal to the 

 difference in frequencies of the contacts and the applied E. M. F. 

 The process is shown in figure 2 where the dots represent the 

 contact points and the broken line the telephone current, the 

 ripples being smoothed out by the reactance of the telephones. 

 The resulting tone is not strictly a beat tone, although the result 

 is exactly the same as though true beats had been produced. 

 This device produces musical continuous wave reception by 

 mechanical instead of by electrical means as in the Fessenden 

 heterodyne. 



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Fig. I . — Diagram of connections for toothed wheel contact maker. 



In 19 13, R. Goldsmith devised the first practical apphcation 

 of this principle in his tone wheel (U. S. Patent No. 1087 113, 

 Feb. 17, 1914), although the circuits shown in the patent were 

 somewhat more compUcated. It was used for some time with 

 the simple circuit described above, both at Arlington and Tuck- 

 erton in 1914. While entirely successful as a receiver in long 

 distance continuous wave communication, it was less sensitive 

 and less adaptable than the oscillating vacuum tube introduced 

 in 191 4 and was, therefore, generally superseded by it. 



Recently the Research Laboratory has again taken up the 

 study of the simplified tone wheel or musical contact maker 



