KNOWLI-.Df'.i: 



March. 1912. 



til account for some of tlic manifold diaractcristics 

 of comets. .\s wc have already shown, it is fairlv 

 well estahlisheil that they aie meteoric swarms. We 

 will tiierefore try to deduce the jihenomeiia th.'it will 

 ensue when suc-h ;i swarm apjiroaches the sun. The 





Comet 1908. III. September 30th, 1908, 47 minutes' 

 exposure. Comefs tail showing distortion. 



particles composing the swarm arc almost cerlainK- 

 kept in leash by mutual gravitation. Every meteor 

 has an independent orbit. 



Almost certainl\- the constituents occasionaih 

 collide. e\en in distant space. Suppose the swarm 

 has approached the Sun. each particle is falling 

 towards him independent!}' of the others, yet acted 

 on by all the others. Some comets have passed less 

 than a radius away from the Sun's surface. TIk 

 parabolic velocitj- acquired by the fall of earli 

 particle to this position would be of the order of close 

 on three hundred miles a second. The near |)articles 

 would he made to move enormously swifter than 

 those at the distant jiart of the swarm. Everv orbit 

 wduld be so disturbed that many of the outer ones 

 would stray away from the general mass never to 

 return. They would continue to move roughlv in 

 the comet's orbit, not. however, by any means e.xactK- 

 so. and a broad swath of meteorites would be i)ro- 

 duced. If the comet were i)eriodic, the varied velocit\ 

 of the particles would cause this field to e.xtend itself 

 until the whole orbit would be more or less sj^read 

 with the meteors. The crowd of particles would 

 not only extend itself lengthways in the orbit, but 

 would broaden also, gradually sjireading space with 

 cosmic dust. It is this spread of material the I'2arth 

 encounters that gives us the iiuninous radiant 

 swarms. 



LUMINCJSITY OF COMETS. 

 When a comet ai)|)r()arhes the Sun. the distmbing 



action of solar attraction would cause maiiv im|)acts. 

 These wouUI temporariK' s|>read the swarm with gas 

 and other resisting material ; this in addition to the 

 heat of innumerable impacts would cause much 

 friction and result in the development of electricitv. 

 l?oth effects would produce luminosity, whilst solar 

 radiation itself would be reflected. When the comet 

 was near the Sun the latter would also be a great 

 heating factor. 



Till-: E.\vi:i.()i'i:s. 



In a number of experimental investigations, I have 

 shown that when matter carries off electricity' it 

 tends to do so in pulses. The potential gradually 

 rises until it produces disruption. This disruption 

 [)roduces heat. This motion of heated molecules 

 seems to possess the power of taking off electricitv, 

 and lowering the potential almost or cpiite to zero. 

 Then the potential commences to grow again until, 

 once more, discharge takes place. Some such action 

 as this may account for the partially ensphering 

 envelopes that seem to be projected from some 

 conict'^. 



Till. Tails oi- thi-; ("omkts. 



W'lieii we consider all the pli}sical facts, by no 

 stretch of imagination does it seem possible to think 

 that the tails of comets are material emanations pro- 

 jected from the head. Is it rational to think of them 

 as a kind of feather or material plume, attached to 

 the nucleus, that swings around at the pace of scores 

 of millions of miles an hour ? Or that it is made up 

 of material particles, projected radialK' from the Sun 

 the whole length of the luminous plume in each new 



The RovatC.ften-.mch Ohscn-atft 



■•mn n phiUcgraph Inkrii ,i: 



FlClKK 129. 



Comet 1908. III. September 29th, 190S, 50 minutes" 

 exposure. The photograph shows a strangely abnormal 

 appearance in the tail, anil apparent distortion, perhaps 

 due to electricity in space. The meteoric swarm is 

 probably difl'iised aronnd a soniewh.it dense centre. 



