§ 45, "specula optima apud majores fuerunt Brundusiana, stanno et aere mixtis").
Uranus was recognized specula of continually augmented size, up to a diameter 4 p pp Herschel.
Despite the fact that their philosophic interests lay rather in ethics and physics, their activity The in what they classified as the third department of specula Stoics.
After much experiment he selected an alloy of tin and copper as the most suitable material for his specula, and he devised means for grinding and polishing them.
Bradley and Molyneux, having been instructed by Hadley in his methods of polishing specula, succeeded in producing some telescopes of considerable power, one of which had a focal length of 8 ft.; and, Molyneux having communicated these methods to Scarlet and Hearn, two London opticians, the manufacture of telescopes as a matter of business was commenced by them (Smith's Opticks, bk.