23i 



B. Davis — New effect produced 



The force exerted upon the cylinders increases very rapidly 

 from the nodes to the middle of the loop. The table is plotted 

 in a curve shown in fig. 3. The ordinates are the square roots 

 of the plate readings. The curve corresponds not badly to a sine 

 curve. Experiments with cylinders of the same length but of 

 smaller diameters gave almost an identical curve. 



O s 1i ~5 to X3 3? 33 "15 ~4S~ 



Experiments made in various gases. — The body of the pipe 

 between the diaphragm and the stopped end forms a closed 

 chamber and into this chamber various gases were introduced. 

 The pipe was still set into action by an ordinary air blast. 

 The sound wave within the pipe was transmitted through two 

 media, air and the gas, the diaphragm forming the division 

 between them. The force of the air blast was kept constant 

 throughout the experiments. The torsional measurements 

 were made only at the middle of the loop. Although the 

 number of vibrations executed by this composite mass of gas 

 changed very much, the position of the node at the diaphragm 

 w 7 as but slightly altered. 



Several readings were taken in air, before and after each 

 experiment with the gases. A fresh supply of gas was intro- 

 duced into the pipe before each reading. The mean results of 

 these experiments in different gases are given in the annexed 

 table. The readings in air, as well as its density are taken as 

 unity. 



Torsion Density 



deflections. of gas. 



Air 1 • 1 • 



C0 2 1-47 1-52 



Illuminating gas '77 "75 



Hydrogen -064 -069 



As will be seen, the force exerted is proportional to the 

 density of the gas. 



The rates of revolution of the system of cylinders mentioned 

 above were also taken in the different gases and the mean 

 result of several experiments are given below, the rate of 

 revolution in air being taken as unity. 



Air. Ilium, gas. C0 2 . Hydrogen. 



1- 1- 1-04 -59 



