45 
in electrical garments with which the regular inhabitants 
are unacquainted. 
The electricity must after all depend on the composition 
of the comet, for known substances do not all show the same 
electrical properties. Hence by assuming comets to be 
composed of various materials, we have a source to attribute 
the different appearances presented by the different indi- 
viduals. To the same source we may attribute the irregu- 
larity in the direction of their tails and the lateral streamers 
they occasionally send out. 
Secondly, I think this electrical hypothesis is sup- 
ported by the to me seeming analogy between comets, the 
corona, and the aurora ; an analogy which suggests that 
they must all be due to the same cause. They may be all 
described as streams of light or streamers, having their 
starting point more or less undefined, and traversing spaces 
of such extent and with such velocities as entirely to 
preclude the possibility of their being material in any sense 
of that word with which we are acquainted. 
The aurora has long been considered as an electric phe- 
nomenon, and recently the same effect has been produced 
by the discharge of electricity of very great intensity 
through a very rare gas, there being no limit to the space 
which it will thus traverse, This being so, why should not 
the tails of comets and the corona also be electric phenomena? 
Their appearance and behaviour correspond exactly with 
those of the aurora, and there is surely nothing very difficult 
in imaoinina’ the sun which is the source of so much heat 
being also the source of some electricity. Neither will there 
appear anything wonderful in the electricity of comets when 
we consider that of the earth. We must not look on our 
inability to explain the cause of such an electric discharge 
as fatal to its existence, for we cannot any more explain the 
existence of the electricity which causes the aurora. If we 
cannot explain from whence these electricities come, we 
