Page:Philosophical Transactions - Volume 029.djvu/440

 I have been obliged to omit ſeveral Particulars of leſs moment: But theſe are the principal Phnomena; 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 the Diſtances thereof. If it ſhall by any be thought a hard 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 terreftrial Matter which may ferve for our purpoſe, than thoſe we have here conſidered, viz. the Magnetical Atoms, and thoſe of Water highly rarified 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 incredible Swiftneſs the Centers both of the Sun and Comet, and to go off into Tails of a ſcarce conceivable Length. What may be the Conſtitution of theſe Cometical Vapours, we 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, ſeldom is ſeen but in the polar Regions of the World, and that moſt commonly in the Winter Months. But whatever may be the Cauſe thereof, if this be not. I have followed the old Axion of the Schools. Entia non eſſe temere nique abſque neciſſitate multiplicanda.

Laſtly I beg leave on this Occaſion to mention what, near 25 Years ſince, I publiſh’d in No 95. of theſe Tranſactions, viz. That ſuppoſing the Earth to be concave,