48 MADEIRA METEOROLOGIC. PART iv. 



of the various suggested modes of operation for the 

 electricity conceived, he writes : " Broadly they group 

 themselves about the common idea that great electrical 

 disturbances are set up by the sun's action in connection 

 with the vaporisation of some of the matter of the 

 nucleus (of the comet), and that the tail is matter carried 

 away, possibly in connection with electric discharges." 



Dr. C. W. Siemens also, in a very late paper read 

 before the Royal Society, London, on " The Conserva- 

 tion of Energy in the Sun," remarks in the matter of the 

 zodiacal light and of comets, that each particle composing 

 them " would have its electric tension vastly increased in 

 its forcible removal (from the solar neighbourhood) in the 

 same way as the fine dust of the desert has been observed 

 by Werner Siemens to be in a state of high electrifica- 

 tion on the apex of the Cheops Pyramid. Would not 

 the zodiacal light also," he asks, " find explanation by 

 slow electric discharge backward from the dust (cos- 

 mical, of which it is composed) towards the sun ? and 

 would the same cause not account for a great difference 

 of potential between the sun and earth, which latter may 

 be supposed to be washed by the solar radial current ? 

 May not the presence of the current also furnish us 

 with an explanation of the fact, that hydrogen, while 

 abounding apparently in space, is practically absent in 

 our atmosphere, where aqueous vapour, which may be 

 partly derived from the sun, takes its place ? An action 

 analogous to this, though on a much smaller scale, may 



