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In truth, the whole party had received a notable tanning, for the winter's sun, weak as it is compared with its summer fervor, has never such an effect upon the exposed skin, as when its rays are reflected from the millions of tiny specula of the glistening ice-field.
As I had all the means and appliances for casting specula at the factory, I soon had the felicity of embodying all my former self-acquired skill in this fine art by producing a very perfect casting of a ten-inch diameter speculum. The alloy consisted of fifteen parts of pure tin and thirty-two parts of pure copper, with one part of arsenic.
It is insusceptible of rust, as gold and silver are, none of the acids affecting it, excepting the aqua regia. It also admits of as perfect a polish as the metal hitherto used for the specula of telescopes. These two properties had suggested to the Spaniards the substitution of it for that use. But the mines being closed up by the government, it is difficult to get the metal.
Two distinguished amateurs, meanwhile, were preparing to reassert on behalf of reflecting instruments their claim to the place of honour in the van of astronomical discovery. Of Mr. Lassell's specula something has already been said. The capabilities of the Newtonian plan were developed still more fully it might almost be said to the uttermost by the enterprise of an Irish nobleman.
The room was a luxurious little apartment with news machines and a broken mirror that had once been en rapport with the crow's nest specula. It seemed a matter of course to Graham that Helen should stop with him. A picture had drifted through his mind of such a vast dramatic struggle as the masses in the ruins had suggested. But here was no spectacular battle-field such as he imagined.
5th- An Artificial Horizon formed of the index specula of a Sextant cemented to a flat board; adjusted by means of a sperit level and the triangular stand before discribed. as this glass reflects from both surfaces it gives the images of all objects much more bright than either of the other horizons; I have therefore most generally employed it in observing the altitudes of stars
But Lord Rosse's 6-foot reflector, 54 feet focal length, constructed in 1845, is still the largest ever made. The imperfections of our atmosphere are against the use of such large apertures, unless it be on high mountains. During the last half century excellent specula have been made of silvered glass, and Dr.
The delicate and complex machinery needed in operations of such hairbreadth nicety as his enterprise involved, the steam-engine which was to set it in motion, at times the very crucibles in which his specula were cast, issued from his own workshops.
A large number of these misty objects, which the utmost powers of Herschel's specula had failed to resolve into stars, yielded at once to the Parsonstown reflector; while many others showed under entirely changed forms through the disclosure of previously unseen details of structure.
William gave lessons to his private pupils, led his orchestra, played the organ and harpsichord, and managed to make ends meet, and would have gotten reasonably rich had he not invested his spare cash in lenses, brass tubes, eyepieces, specula and other such trifles, and stood most of the night out on the lawn peering at the sky.
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