VOL. XXIX.] PHILOSOPHICAL TRANSACTIONS. 225 



cause of its effervescence at length abating, or perhaps the matter consumed, 

 these effluvia should at length subside, and form those two bright laminae 

 which we have described, and, whose edges being turned to us, were capable 

 to emit so much light that we might read by them. I choose to call them 

 laminae, because, though they were but thin, doubtless they spread horizontally 

 over a large tract of the earth's surface. And while this luminous matter 

 dropped down from the upper plate to the under, the many little white columns 

 were formed between them by its descent, only visible for the moment of their 

 fall. These by the swiftness with which they vanished, and their great number, 

 showing themselves and disappearing without any order, exhibited a very odd 

 appearance; those on the right seeming sometimes to drive and push those on 

 the left, and vice versa. 



These are the principal phaenomena ; of whose causes I should have more 

 willingly and with more certainty given my thoughts, if I had had the good 

 luck to have seen the whole from beginning to end; and to have added my 

 own remarks to the relations of others : and especially if we could by any means 

 have come at their distances. If it shall by any be thought a bold supposition, 

 that I assume the effluvia of the magnetical matter for this purpose, which in 

 certain cases may themselves become luminous, or rather may sometimes carry 

 with them out of the bowels of the earth a sort of atoms proper to produce 

 light in the ether : I answer, that we are not as yet informed of any other 

 kinds of effluvia of terrestrial matter which may serve for our purpose, than 

 those we have here considered, viz. the magnetical atoms, and those of water 

 highly rarefied into vapour. Nor do we find any thing like it in what we see 

 of the celestial bodies, unless it be the effluvia projected out of the bodies of 

 comets to a vast height, and which seem by a vis centrifuga to fly with an in- 

 credible swiftness, the centres both of the sun and comet, and to go off into 

 tails of a scarcely conceivable length. What may be the constitution of these 

 cometical vapours, we the inhabitants of the earth can know but little, and 

 only that they are evidently excited by the heat of the sun; whereas this 

 meteor, if I may so call it, is seldom seen except in the polar regions of the 

 world, and that most commonly in the winter months. But whatever may be 

 the cause of it, if this be not, I have followed the old axiom of the schools, 

 Entia non esse temere neque absque necessitate multiplicanda. 



Lastly, I beg leave on this occasion to mention what, near 25 years since, I 

 published in N° 195 of these Transactions, viz. That supposing the earth to be 

 concave, with a less globe included, in order to make that inner globe capable 

 of being inhabited, there might not improbably be contained some luminous 



VOL. VI. G G 



