Joseph Priestley


Period I, page 8.
The antients engravers of gems are supposed to have made use of glass globe filled with water to magnify their figures.


Period I, page 24.
In his Specula Mathematica, Roger Bacon added some observations upon the roundness the image of the sun made by rays of light passing through an angular operture; a phenomenon which had employd Aristotle and his disciples.


Period II, page 34.
Maurolycus also hit upon the true solution of the problem concerning the image of the sun appearing round, though the rays that form it are transmitted into a dark room through an angular aperture.


Period IV, page 170.
Descartes says, that James Metius, of Alcmar, in Holland, the same person whom he ascribes the invention of telescopes, and who took great pleasure in making lenses and burning glasses, sometimes made them of ice, and did not find that substance unfit for his purpose.


Period IV, page 211.
It was with telescopes made by Campani that Cassini discovered the nearest satellites of Saturn. They were made by the express order of Lewis XIV, and were of 86, 100, and 136 Parisian feet focal lenght


Period IV, page 211.
Campani sold his lenses for a great price, and he took every possible method to keep his art of making them a secret.


Plate II, figure 14.
Camera obscura



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