April 17, 1908] 



SCIENCE 



615 



to about that used in speculum metal, the 

 diamagnetism increased to a maximum and 

 then decreased, making the susceptibility 

 of the alloy a complex function of the per 

 cent, of tin and copper present. The 

 maximum diamagnetic susceptibility of the 

 alloys was about — 2.1 X 10"°. 



A Satisfactory Form of High Resistance: 

 G. "W. Stewart, University of North 

 Dakota. 



There is an increasing demand for a 

 satisfactory form of very high resistance. 

 This paper makes record of a very con- 

 venient and satisfactory form of high re- 

 sistance in which carbon is utilized, and 

 also furnishes data concerning its con- 

 stancy. Commercial lampblack mixed with 

 a lacquer, "zapon L, " is spread into films 

 upon an insulating base. These films are 

 permanent, are not subject to ordinary 

 changes in temperature, do not evaporate, 

 and do not crack. Such films are very 

 easy to make, and can be given practically 

 any range. The resistance temperature 

 coefficient of such films when hard rubber 

 is used as a base, is from 0.1 to 0.2 per 

 cent. 



Phonographic Record of the Doppler 

 Effect: Chas. T. Knipp, University of 

 Illinois. 



In this paper an attempt was made to 

 obtain a phonographic record of the Dop- 

 pler effect. The phonograph was placed 

 at the side of the track, and distant about 

 thirty feet. The horn was directed toward 

 the moving source of sound. A record 

 was taken of a continuous blast of the 

 locomotive whistle sounded over a distance 

 of about 1,000 feet— 500 feet on either side 

 of the position of the observer. By simple 

 calculation it can be shown that the pitch 

 will be lowered one tone when the train 

 velocity is 44 miles per hour or 64 feet per 

 second. The train in question was moving 

 at a velocity of 57 miles per hour or 84 feet 



per second. The pitch accordingly should 

 be lowered 9.3/8 tones. The phono- 

 graphic record when reproduced showed a 

 distinct lowering of the pitch — fully a tone 

 as far as it was possible to judge by the 

 ear. 



Hotv does the Violinist control the Loud- 

 ness of his Tone: Haevet N. Davis, Har- 

 vard University. 



One conclusion of the Helmholtz theory 

 of the motion of a violin string does not 

 seem to agree with experience, viz., that if 

 the bowing point is fixed, the loudness of 

 the tone depends wholly upon the speed of 

 the bow and not at all upon its pressure. 

 In explanation of this discrepancy, it is 

 found that a certain pressure corresponds 

 to each bowing speed, and that below this 

 pressure the Helmholtz form of vibration 

 can not be maintained. 



The author is led to believe that the 

 actual motion of a violin string is not 

 usually of the normal Helmholtz type, but 

 of the sort described in his paper a year 

 ago as corresponding to light bowing. 

 With the special apparatus devised it is 

 possible to reduce the energy of the vibra- 

 tion to barely half its normal value, and 

 the author hopes to be able to determine 

 the limits of the sub-critical region for an 

 actual violin and compare with them ob- 

 servations already obtained of the pres- 

 sures ordinarily used. 



A Wave Machine shoiuing Damped or 



Undamped Compound Waves: Albert 



B. Porter. (Read by title.) 



This machine compounds two harmonic 



waves either or both of which may be of 



constant amplitude, may have any desired 



damping coefficient, or may increase in 



amplitude at any desired rate. It thus 



serves not only to illustrate the ordinary 



problems in simple harmonic motion, but 



also the effects of damping by frictional or 



