and thereby accommodate a much greater multitude of Inhabitants.
But still it will be said, That without Light there can be no living, and therefore all this apparatus of our inward Globes must be useless: To this I Answer, That there are many ways of producing Light which we are wholly ignorant of; the Medium it self may be always luminous after the manner of our Ignes fatui. The Concave Arches may in several places shine with such a Substance as invests the Surface of the Sun; nor can we, without a boldness unbecoming a Philosopher, adventure to assert the impossibility of peculiar Luminaries below, of which we have no sort of Idea. I am sure the Poets Virgil and Claudian have gone before me in this Thought, inlightning their Elysian Fields with Sun and Stars proper to those infernal, or rather internal Regions. Virg. Æneid. 6.
And Claudian lib 2. De Raptu Proserpinæ.
And though this be not to be esteem'd as an Argument, yet I may take the liberty I see others do, to quote the Poets when it makes for my purpose.
Lastly, To explain yet farther what I mean, I have adventur'd to adjoin the following Scheme, (Tab. 1. Fig. 3) wherein the Earth is represented by the outward Circle, and the three inward Circles are made nearly proportionable to the Magnitudes of the Planets Venus, Mars and Mercury, all which may be included within the Globe of Earth, and all the Arches more than sufficiently strong to bear their weight. The Concave of each Arch, which is shaded differently from the rest, I suppose to be made up of Magnetical Matter; and the whole to turn about the same common Axis pp, only with this difference, that the Outer Sphere still moves somewhat faster than the Inner. Thus the Diameter of the Earth being about eight thousand English Miles, I allow five hundred Miles for the thickness of its Shell, and another space of five hundred Miles for a Medium between, capable of an