Very — On a Possible Limit to Gravitation. 41 



spherical by close approximation, may ultimately pass 

 into and coincide with a complex of magnetic equip oten- 

 tial surfaces, so that the wave-propagation is not radial, 

 save by close approximation at the start, but follows the 

 direction of the curved lines of magnetic force in the field 

 as finally " magnetically ' ' controlled, and thus returns 

 into itself at the point of initiation. This conception has 

 some analogy with Newcomb's idea that space returns 

 into itself through a fourth dimension; but the latter is 

 highly recondite, and indeed transcendental, whereas my 

 proposition is quite simple and is not disproved by any 

 known facts. Newcomb's conception appeals to me 

 strongly as a feasible means of passing through an inter- 

 mediate from the world of nature to a world of pure 

 spirit which is not in space of three dimensions; and 

 perhaps the full explanation of gravity will require this 

 further extension of rational thought into the region of 

 genuine causes ; but for the present this greater problem 

 and border region of science may be omitted. 



If the magnetic analogy be accepted, no energy is 

 wasted in maintaining the mechanism of gravitation. 

 Moreover, the elasticity of the aura is almost infinite, so 

 that the velocity of propagation of the gravitational wave 

 is enormously greater than that of light. 5 According to 

 Professor Fessenden's computation, 6 the velocity of the 

 gravitational wave is 5 X 10 36 cm. per sec. This is of 

 course simply an inference, but one which rests on reli- 

 ably known electrical data. Let us suppose that the 

 radius of an aural cell, or the maximum distance to which 

 gravitation is propagated, is 1000 light-years, which will 

 be near enough for a first approximation to the order of 

 the magnitudes involved. The radius of the vortex is 

 then something like 3X(10) 10 light- seconds, or 3 X 

 (10) 10 X v«=9 X (10) 2 * cm., if v is the velocity of light; 

 and a complete circulation along a magnetic line of force 

 which extends to this radial distance will be three times 



5 Thomson's (Lord Kelvin's) discussion of a mathematical proposition 

 by Green, in the course of which he arrived at the conclusion that the veloc- 

 ity of gravitation (contrary to the almost universal opinion of astronomers) 

 can not be large, may be placed alongside of his opinion that "it is 

 absolutely impossible to conceive of the currents which he [Ampere] 

 describes round the molecules of matter, as having a physical existence" 

 (Papers on Electrostatics and Magnetism, p. 469). The currents of elec- 

 tronic revolution around the atoms are now thoroughly established, in spite 

 of Lord Kelvin. 



6 R. A. Fessenden, A Determination of the Nature and Velocity of Gravi- 

 tation, Science, N. S., vol. 12, p. 744, November 16, 1900. 



