Astronomical dialogues between a gentleman and a lady, wherein the doctrine of the sphere, uses of the globes, and the elements of astronomy and geography are explain'd in a pleasant, easy and familiar way / With a description of the famous instrument called the orrery. By J[ohn] H[arris] F.R.S.

  • Harris, John, 1667?-1719.
Date:
1719
Catalogue details

Licence: Public Domain Mark

Credit: Astronomical dialogues between a gentleman and a lady, wherein the doctrine of the sphere, uses of the globes, and the elements of astronomy and geography are explain'd in a pleasant, easy and familiar way / With a description of the famous instrument called the orrery. By J[ohn] H[arris] F.R.S. Source: Wellcome Collection.

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    But we may fairly conclude, that all the vaft Spaces both between and beyond the Planetary Syftem, are filled with no Mat¬ ter capable of making any confiderable Refiftance to their Motions, but rather are an immenfe Void, or Vacuity. I think that is a very probable Conclu- fion, faid (he} for if there were any quan¬ tity of refilling Matter, it mult always obftruft a little, and by degrees mull make very fenfible Alterations in the Planets Motions •, which I don’t find to have been in Fa£t difcovered} but fare. Sir, thefe Comets mull go off to vaft Di- ftances from the Sun ? Yes, Madam, faid T, and therefore they are ftill more unfit than any of the other Planets, to be inhabited by fuch kind of Beings, as thofe of human Race \ for the middle Diftance of the Great Co¬ met that appeared in 1680, was more than 500O millions of Miles from the Sun \ as its greateft Diftance was above twice as much \ and yet its leaft Diftance was not above a 20,000th part of its greateft: fo that in its whole Revolution, it would be fubject to fuch Extremities, as that its greateft Degree of Light and Heat to its leaft, were above 400 millions