Dr. Gregory's Elements of catoptrics and dioptrics / Translated from the Latin original, with a large supplement, by William Browne.

  • Gregory, David, 1659-1708.
Date:
1735
Catalogue details

Licence: Public Domain Mark

Credit: Dr. Gregory's Elements of catoptrics and dioptrics / Translated from the Latin original, with a large supplement, by William Browne. Source: Wellcome Collection.

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    # . v and view them as perfedly and diftindly as if we could fumtfion them before us, and command them to the End of our Eelefcope. This has brought us into a per fed: Acquain-* tance with thole furprizing Parts of the Cre¬ ation, which are far feparate from this Globe of ours, and with which we are allowed no Commerce but Looking. We can now per¬ ceive the Sun to be a vaft Globe of Fire, and by the different ‘Phafes of all the Pla¬ nets, that he is the Fountain of all their Light. The Surfaces of mod of them ap¬ pear like fo many Maps of Land and Water, and there are few now but allow both them and the fixed Mars fome nobler Ufe than to twinkle upon us o’Nights. By fixing upon fome remarka le Spots on their Surfaces, and obferving how they fhift their Pofition, and in what time they again return to the fame Place, we determine the Motion of thefe Bodies round their Axes, and the Time in which that Revolution is perform¬ ed. Several jecondary ‘Planets, or Satel¬ lites, which were too fmall for the naked Eye, are now difeerned to move round Ju¬ piter and Saturn, as the Moon round our Earth $ and about the laft of them is fecn the particular Phenomenon of an Annulus, or King. Nor is the Difcovery of thefe Satellites merely fpeculative, but of prodi- [ b 2 ] gious