340 G. 8. Moler — Transverse Vibrations of Cords and Wires, 



ling cord. This was attached to the crank of the main shaft 

 and with a load of 25 kilograms gave a speed of 4986 revolu- 

 tions, as a mean of four consecutive determinations; the 

 greatest variation from the mean being 10 revolutions, which 

 error lies within the limit of accuracy of the determination. 

 At this speed the controlling cord was formed into a single 

 segment having a diameter of about 8 cm . 



During the first half of the experiment, in addition to the 

 controlling cord, a single cord was used. It was then replaced 

 by four strands and finally by a single cord driven from the 

 second crank. 



Now if !N" be the number of vibrations per unit of time, L 

 the length of the cord, n the number of segments and V the 

 velocity of transmission of an impulse transmitted to the cord, 

 we have the familiar formula expressing the transverse vibra- 

 tions of flexible cords ; 



If P is the tension of the cord, s its cross section and d its 

 density : we shall have 



w 



Finally if X is the wave length, 



n 



V = NA, 



and 



y sd IST2L 



In the following table the single set of observations already 

 referred to are given, for the purpose of exhibiting the per- 

 formance of the apparatus under variations of cross section, 

 length, speed and tension. The results agree quite closely, 

 obtained as they were from a single determination of each 

 quantity, and they show the application of the apparatus to the 

 demonstration of the laws embodied in the general formula. 



A very interesting form of vibration is obtained by stretch- 

 ing a cord at 45° with the line of the shaft. The crank then 

 gives a longitudinal impulse and a transverse impulse at the 

 same time; the longitudinal impulse being an octave lower 

 than the transverse. The cord thus has a resultant motion in 

 which its vibrations as a whole and in two segments are plainly 



