Jandabt 30, 1920] 



SCIENCE 



103 



traction by the material of the unelectrified 

 large spheres. Professor Nipher calls this a 

 " gravitational repulsion," but this appears to 

 be a misnomer. If the lead had really be- 

 come gravitationally repulsive, it should also 

 repel the earth, and the leaden spheres should 

 rise up and float away. Needless to say, this 

 is not what happens. Contrary to the usual 

 conception of a static charge, the electric 

 charges have penetrated into the substance of 

 the metal. Since it is thus shown that a 

 charge of electricity, which in other respects 

 would not be distinguished from a static 

 charge, has in this instance slowly been ab- 

 sorbed by the metal, permeating its substance, 

 the thin metal of the protecting case can be 

 no barrier to the transmission of such a 

 charge as this, and the metal case no longer 

 protects the inner balls of lead from directly 

 receiving a corresponding electric charge of 

 the same sign as that of the large spheres, 

 and thus there is repulsion between the two, 

 no matter whether the electrification be posi- 

 tive or negative. However, since the electric 

 penetration progresses very slowly, the large 

 spheres presumably take more time to charge 

 up than the small spheres. Consequently, if 

 after a preliminary application of one sort of 

 electricity for a sufficient time to produce 

 saturation, the electrification is changed to 

 the opposite sort, we should expect that the 

 electrification of the small spheres would 

 change sign first, and for a while there should 

 be electric attraction, or at least a progress- 

 ively diminishing repulsion, l^ow this is ex- 

 actly what takes place, though sometimes with 

 rather vigorous tremors, as if the interior 

 distribution of the electricity were not quite 

 uniform and as though its unloading were 

 spasmodic; but eventually, if the experiment 

 endures long enough and the electrification is 

 sufficiently powerful the signs of the electric 

 charges become the same in both large and 

 small spheres and the temporary electric at- 

 traction changes back to a repulsion. There 

 are some anomalies connected with the orien- 

 tation of the applied electricity when direct 

 contact of brushes is the method of applica- 

 tion, which possibly signify that the lead 



spheres are not entirely homogeneous for 

 charges communicated in this way. 



While the gravitational and electrical 

 forces are intimately related, insomuch that 

 a common entity — the electron — is presum- 

 ably concerned in both, their modes of action 

 and speeds of transmission appear to be 

 entirely difFerent. The electric phenomena 

 which counterfeit gravitation in the pre- 

 ceding experiment, are irregularly variable 

 and slow. Gravity is constant and its im- 

 pulses so rapid in their transmission that 

 their speed has never been directly measured. 

 There is no reason to suppose that gravity is 

 conveyed by electro magnetic vibrations with 

 the speed of light, for these imiformly give 

 repulsion, and not attraction; nor is the final 

 action of the penetration of the electric 

 charges other than repulsion, while, in spite 

 of Professor Cipher's title, there is no evi- 

 dence of any gravitational repulsion. 



From the result of Nipher's experiment, we 

 may infer that the penetration of electrons, 

 emitted by the sun from time to time and 

 entering into the substance of earth and 

 moon, will produce a variable electric repul- 

 sion between these neighboring bodies, and 

 it is conceivable that some of the unaccounted 

 irregiilarities in the moon's motion may be 

 produced in this way. 



The positive electric potential of the at- 

 mosphere increases in an upward direction, 

 at first slowly, then more rapidly, though 

 sometimes quite irregularly, often attaining a 

 value of tens of thousands of volts at a height 

 of a few miles. This electrification of the 

 air is the result of the ionization of some of 

 its ingredients through absorption of the 

 sun's rays. The ionization is greatest in the 

 upper air, partly because the incoming rays 

 are there rich in the ultra-violet rays which 

 are the most efficient ionizers, and the upper 

 layers are the ones which first take toll of the 

 radiation before these rays have been depleted ; 

 but the electrification is also greater in the 

 upper air partly because these layers are 

 furthest from the surface of the gromid 

 and can not lose their charge by conduction 

 to the ground as easily as the lower layers. 

 Although air is a very imperfect conductor. 



