﻿Non-Newtonian Mechanics. 375 



much greater than that of the jets from other orifices ; in 

 some cases the sensitiveness of a simple flame jet would 

 approximate to that of the ear itself. 



The flaring appears to depend, for a certain range of 

 diameters of orifices, almost simply upon the linear rate 

 of flow at the orifice. For diameters above this range, flaring 

 occurs at much lower pressures. 



The high temperature in ignited jets leads to increased 

 viscosity, and this tends to explain the higher pressures then 

 admissible. For a given pressure and orifice, the rate of 

 flow is greater for an unignited than for an ignited jet. 



In conclusion we wish to thank Professor Wilberforce for 

 the keen interest which he has shown in these experiments. 



Georp-e Holt Physics Laboratory, 

 University of Liverpool. 



XXXIII. Non -Newtonian Mechanics, The Mass of a Moving 

 Body. By Richard 0. Tolman, Ph.D., Assistant Pro- 

 fessor of Physical Chemistry at the University of Cincinnati*. 



AN acceptance of the Einstein theory of relativity neces- 

 sitates a revision of the Newtonian system of mechanics. 

 In making such a revision it is desirable to retain as many as 

 possible of the simpler principles of Newtonian mechanics. 

 Some of the consequences have already been presented f of 

 a system of mechanics which retains the conservation laws 

 of mass, energy, and momentum, and defines force as the 

 rate of increase of momentum ; but to agree with the 

 theory of relativity introduces an idea foreign to Newtonian 

 mechanics by considering that both the mass and velocity 

 of a body are variable. 



From the theory of relativity, Einstein has calculated both 

 the transverse and the longitudinal accelerations experienced 

 by a charged body moving in an electromagnetic field. On 

 the basis of these accelerations, it has been usual to place 

 the " transverse mass " of a body moving with the velocity u 

 as equal to m / \ 7 1 — u 2 /c 2 , and its "longitudinal" mass as 

 equal to m /(l — w 2 /° 2 )S where m is the mass of the body at 

 rest and c is the velocity of light. If, however, mass is a 

 quantity to which a conservation law applies, the mass of 

 a body cannot well be different in different directions ; and 



* Communicated by the Author. Contribution from the Chemical 

 Laboratory of the University of Cincinnati. 



t Lewis, Phil. Mag, xvi. p, 705(1908). Lewis & Tolman, Phil. Mag. 

 xvii. p. 510^1909). Tolman, Phil. Mag. xxi. p. 296 (1911) ; x.vii. p. 468 

 (1931). 



