PART II. POLAR MAGNETIC PHENOMENA AND TERRELLA EXPERIMENTS. CHAP. V. 619 



Let us now see how we can explain the characteristics that have been observed in the zodiacal 

 light, by supposing that in the sun's equatorial plane there exists a flat ring of radiant streams of 

 matter, consisting principally of primary rays and streams of atoms from the sun, and perhaps also of 

 secondary rays emitted from cosmic dust moving in the same plane and which are irradiated by the 

 primary beams from the sun. 



If these corpuscle-rays and streams of atoms either themselves emit luminous rays or scatter 

 the light of the sun, we will, as we shall soon find, be enabled more satisfactorily than ever to explain 

 the characteristics of the zodiacal light. 



It will be at once observed that my idea of this flat ring about the sun has a certain resemblance 

 to what is called the meteoric theory, as it also presupposes that a ring of cosmic dust exists which 

 encircles the sun, more particularly in the plane of the solar equator. 



The idea perhaps equally resembles the theory advanced by MAIRAN in 1731, that the zodiacal light 

 is reflected from the sun's atmosphere, stretched out into a flattened spheroid or lenticular shaped body 

 revolving with the sun; an idea which LAPLACE has for ever set at rest by demonstrating that the sun's 

 atmosphere "can extend no further than to the orbit of a planet whose periodical revolution is performed 

 in the same time as the sun's rotary motion about its axis, or in twenty-five days and a half; that is 

 only as far as 8 / ao of Mercury's distance from the sun". 



We shall, however, soon see that my theory has an equally great resemblance to an entirely 

 different view of these phenomena, namely, to the idea arrived at by JONES after discussing the results 

 of his excellent observations : "I offer now, as a last conclusion, the hypothesis of a nebulous ring with 

 he earth for its centre". In reality my theory combines the advantages of all earlier hypotheses, and 

 it succeeds in explaining phenomena which none have elucidated previously, for instance the phenomenon 

 of the counter-glow Gegenschein and the pulsations in the brightness and outline of zodiacal light. 



From what we have learnt from our experiments we can foresee what will happen when our 

 nagnetic earth advances in the assumed ring of radiant matter that surrounds the sun. 



The earth magnetism will cause there to be a cavity around the earth in which the corpuscles are, 

 ;o to speak, swept away, a space around the earth from which a portion of the radiant matter has 

 disappeared. 



This cavity round the earth is doubtless not circular in such a way as JONES supposes with his 

 lebulous ring hovering about the earth in the sun's equatorial plane, but the space has a somewhat 

 lifferent form which we can describe and note particulars of very closely, owing to our earlier expe- 

 dients as will be seen in the following. 



Diagrams showing a section of JONES'S and my spaces respectively round the earth, spaces that 

 ire free from corpuscles, will be seen in figs. 224 and 225. 



We shall now easily understand that we have here an explanation of "the brightness in the east 

 >efore sunrise", owing to the streams of corpuscules from the sun, when they approach the earth suffi- 

 iently, becoming deflected in the same manner as the rays shown in the fig. 219, and as it is further 

 >lainly shown on the morning side of the picture No. 16, fig. 215, which is as seen taken from the 

 outh pole. 



In like manner it makes it easy to explain naturally "the brightness which appears in the western 

 ky after sunset" by referring to numerous pictures with the ist sectional line, also called the ist line 

 >f precipitation, of the rays; this is in a manner a boundary-line along which the cathode rays begin to 

 ravel around the terrella in curves regulated by the stiffness of the rays and by the magnetic condition 

 >f the terrella. See particularly the same picture 16, fig. 215, on the evening side. 



