PART II. POLAR MAGNETIC PHENOMENA AND TERRELLA EXPERIMENTS. CHAP. VI. 663 



Schuster considers that the velocity of such cathode-particles, as they sweep past the earth, is 

 duced to about nine kilometres per second, and that the passage between the sun and the earth would 

 ke about a year, so that the magnetic effects of such rays could not reproduce, even roughly, the 

 laracteristic features of a magnetic disturbance. 



He does, it is true, say at the conclusion of his paper: 



"It is otherwise with the more refined form in which the theory has been presented by Prof, 

 rkeland, who, qualitatively at any rate, has shown that an agreement might be reached, if we can 

 lagine the particles to be drawn in towards the earth by its magnetic forces, so that for the time being 

 eir motion is regulated by the position of the earth's magnetic poles. Nevertheless, the argument from 

 u-rgy and from electrostatic considerations alike, has now been shown to be fatal to the theory in 

 .iy form". 



I do not think, however, that Schuster's objections have any serious bearing on my theory, if we 

 i nsider the properties which the new sunbeams must be assumed to possess. 



1 have shown that cathode-rays from the sun, which are to strike down towards the earth in the 

 : rora polaris zones, must have a transversal mass about m = 1.83 X io 3 X m . In other words, the 



I li^itudinal mass of our particles is 6 milliard times greater than the mass of the particles upon which 

 .'huster calculates in his energy-comments. Thus these cathode-rays will pass the earth, not with a 

 'Incity of 9 kilometres, but with a velocity very little short of that of light. 



In his further development, Schuster shows that ordinary cathode-rays that issued from the sun in 

 Swell-defined, narrow pencil, would instantly be dispersed; for the electrostatic repulsion to which a 



I 1 tide near the limits of the pencil would be subjected from the other particles in the pencil of rays, 

 i mid, according to Schuster's calculation, impart to an electron an acceleration so great that in the very 

 I st second it would fly over a distance of astronomic magnitude. 



If the calculation is applied to our rays, this acceleration would have to be divided by 3.3 millions, 

 lit even with such an acceleration, an electron would move to a great distance in the 500 seconds that 

 .'ray with the velocity of light takes in passing from the sun to the earth. 



There is still, however, another point of great importance to be considered, and that is that in my 

 t mry the magnetic storms on the earth are not caused by a great, more or less cylindrical pencil of 

 i i-s at a great distance from the earth, but generally a small, fine pencil of rays is drawn in in an arc 

 c wn to a minimum distance of from 200 to 300 km. from the earth in the aurora polaris zones. These 

 i drawn pencils of rays act partly directly over the earth, partly indirectly by the earth-currents which 

 t _-\' induce. 



Let us return to our experiments. If the globe is 



Jghtly magnetised, the patches of eruption are seen to 

 "ange themselves in zones, with long pencils issuing into 

 pace, almost as in fig. 249; only these pencils are bent 

 I the magnetism, which is exactly analogous to what we 

 1 ve assumed regarding the cathode-rays issuing from 

 t sun. 



These centres of eruption for the disruptive discharges 

 more marked by the addition of some Leyden jars 

 I rallel to the discharge-tube; but care must be taken not 

 t add too much capacity, as the discharge may then be- 

 cme oscillatory. I have generally employed about io to 



: milliamperes as the discharge-current for the globe of Fig. 349. 



(centimetres diameter. 



