KENNELLY AND UPSON— HUMMING TELEPHONE. 



333 



upper ziz-aag line /. The current strength, on the cl.c. milHammeter, 

 as shown at p on the lower ziz-zag line I, was 130 milliamperes. 

 When the telescopic tube was gradually shortened, the pitch of the 

 note steadily rose, until it reached Q, at A"S (920^-'), with 240 

 cm. of tube-length, and a primary current strength q of 200 mas. 

 The intensity of the note near 920 ■—' was ordinarily somewhat 

 weaker than when near 825 r-'. On continuing to shorten the tube, 

 the pitch suddenly broke from Q, at 920 — ', to R at 825 —'. Pushing 



Fig. 



60 ao lOO 120 ItW 160 180 zoo ZZO ZUO 260 



TUBt LENGTH • CENTIMETERS 



2. Effect of Shortening Tube, and of Reversing Receiver Connections. 



in the tube further, the pitch would again climb steadily to T, at 

 201 cm., with a new maximum of current. Beyond this point, the 

 pitch would break suddenly to U at 810 r~^. Again it would climb 

 to W, at 170 cm. and suddenly collapse to A'. Continuing in this 

 manner, the pitch would alternately rise to maxima and break sud- 

 denly to minima, along the pitch zig-zag /. At the breaks of pitch, 

 the current would sometimes break to a lower value, as at t, n; or 

 break to an upper value, as at zv, x; or vary suddenly in rate of 

 change, without discontinuity in magnitude, as at q. Repeating the 

 experiment, the zig-zag lines of pitch and of current would be 

 repeated, not exactly but substantially, the variations being due not 



PROC. .'VMER. PHIL. SOC. , XLVII. 189 V, PRINTED 0CT03ER 2, I908. 



