788 Sir Oliver Lodge on 



This distance, therefore, for a 100 metre wave is very- 

 great, and for a 10 kilometre wave is 2000 kilometres. 



The case of interstellar space. 



As to an infinitesimal opacity of interstellar space dne to 

 this cause, assuming that any ionization goes on there at all,, 

 it is only a question of how long it will be before even light- 

 waves are absorbed ; though long waves are much more 

 readily dealt with. Let there be only half an electron 

 produced per c.c. per second, and take the wave-length as 

 6xl0~ 5 centimetre, the absorption-distance in such a case 

 is 10 33 centimetres, which corresponds to a light journey of 

 10 15 years. 



The other or scattering kind of absorption above spoken 

 of is therefore likely to be of much greater proportional 

 influence, so far as the short waves of light are concerned ; 

 and in the immediate neighbourhood of the sun Sir J. J. 

 Thomson thinks it likely that it may partially account for 

 the Corona. 



But in any solar system region of space, where electrons 

 are plentifully produced, long Hertzian waves will be liable 

 to become absorbed and to exhibit their energy in the form 

 merely of streams of corpuscles. 



Summary. 



Part I. of this paper gives the theory of the Groldschmidt 

 Dynamo, for any number of circuits, up to a magnifying 

 ratio of 10. 



Part II. deals with obstacles to electric wave transmission 

 due to various kinds of opacity, or virtual opacity, in the 

 atmosphere ; and emphasises the important influence which 

 the highly conducting layer necessarily existing at a certain 

 height must play, with fluctuations according to whether it 

 is uniformly spherical or irregular in shape, and with 

 reference also to the distribution and amount of its 

 ionization. It is suggested that sunshine interferes with 

 this layer ; either by altering its shape through heat, or by 

 making its transition more gradual through general supply 

 of /3 particles. It is also suggested that under the action of 

 solar radiation of all kinds electrons may be momentarily 

 set free enough to promote several newly-expected kinds of 

 atmospheric opacity. Incidentally a useful practical ex- 

 pression for radiation from an aerial is given in equation (5). 



