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an interpretation of the existence of a number of these 
cloudy strata floating in the comet’s atmosphere in con- 
centric rings around its central mass in the presence of 
atmospheric ingredients of different chemical constitu- 
tion, or in supplies of vapour furnished from the same 
source at different intervals of time as indicated in the 
alternate violent action and total cessation of the steamy 
jets which have been observed to take place. But whilst 
all this is going on upon the anterior or sunward side 
of the comet, there is quite another state of affairs on the 
opposite side. There the planetary mass and its cloudy 
canopies project their shadows and their shades into a 
vast conoidal space beyond, a space in which total and 
partial eclipses of the sun prevail, where the influence of 
the solar rays is felt with mitigated force, and where, con- 
sequently, a misty precipitation is formed, which becomes 
illuminated in the penumbra by the direct rays of the par- 
tially eclipsed sun, and throughout its whole extent by 
the scattered beams which penetrate the bank of filmy 
clouds floating over the central planetary mass, and stretch- 
ing away in a direction from the sun, forms that illumi- 
nated appendage known as the cometary tail. 
It will be perceived, however, that though condensation 
would be commenced, where the temperature was sufficiently 
mitigated, throughout the whole of that coniodal space, 
darkened by the intervention of the planet and its clouds, 
yet, when once commenced, the inner particles of cloud 
being largely protected from further radiation by those 
external to them, the sum total of condensation would be 
almost confined to an annular space near the circumference 
of the shadow, in short, the misty cloud would have the 
