LET. XXI. OF THE SUN, MOON, AND PLANETS. Z7Z

was effected by the immense quantity of humidvapours which composed its tail: and Mr. Wins-ton, who supported this conjecture with muchingenuity, was likewise of opinion, that thegeneral conflagration will be occasioned by ourbeing involved in the tail of the same comet,after it has been prodigiously heated in its pas-sage from the sun.

Sir Isaac Newton, on the contrary, conjec-tured, that this, as well as all the other comets,coming nearer and nearer to the fun in everyrevolution, would at length fall into this lumi-nary, and serve as aliment, or fuel, to supply theloss of matter, which must arise from the conti-nual emission of the particles of light. These,however, are mere hypotheses, and as such, butof little value. The fame also may be said ofevery thing that can be advanced concerningtheir being inhabited worlds: for if animals canexist there, they must be creatures very differentfrom any that we have the least conception of.Some, who have indulged themselves in visionaryideas of this kind, have imagined, from the pro-digious vicissitudes of heat and cold which theyare subject to in different parts of their orbits,that they are the receptacles of reprobated spi-rits ; and others, with equal propriety, place theinfernal dominions in the fun.

It must be observed, however, that the con-jectures concerning planetary worlds are notB b 3 so