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"`Elutriation as applied to Emery and other Powders." Lastly he took up the fourth, and read half to himself "`The method practised by Monsieur Foucault in silvering the surfaces of glass specula. I seem to have dipped into the wrong drawer, dad," he said coolly. James Brandon groaned. "I made so sure that I had got the right things. They do look like legal papers, don't they?"
All that is requisite is to have a clean-planed wrought-iron or brass fixing-plate, to which the work in hand can be attached at a few suitable parts with soft solder, as in the case of the turning lathe above described. A Method of casting Specula for Reflecting Telescopes, so as to ensure perfect Freeness from Defects, at the same time enhancing the Brilliancy of the Alloy.
In all probability they were then for the first time seen; for although Professor Holden made out a plausible case in favour of the fitful visibility to Herschel of each of them in turn, Lassell's argument that the glare of the planet in Herschel's great specula must have rendered almost impossible the perception of objects so minute and so close to its disc, appears tolerably decisive to the contrary.
He was accompanied by his daughter. They spent several days with us. The weather was most enjoyable. I had much conversation with Sir John as to the Sun spots and willow-leaf-shaped objects on the Sun's surface, as well as about my drawings of the Moon. I exhibited to him my apparatus for obtaining sound castings of specula for reflecting telescopes.
"Wouldn't do to break that now, Tom, my boy." "Break it?" cried the boy; "oh, it would be horrible. Why, we should have to make another, and go through all that again." "Yes, Tom, but we could do it. I know of a gentleman who made a hundred of these specula with his own hands. But there will be something more interesting for you to see to-morrow." "What, shall we get it done?"
Monday and Tuesday, she continues, 'were tolerably quiet, our hearts beating fast in the hope of La Marmora's approach, the streets barricaded, and none but foreigners and women allowed to leave the city. On Wednesday, La Marmora came indeed, but in the ugly form of a bombardment; and that evening the Jenkins sat without lights about their drawing-room window, 'watching the huge red flashes of the cannon' from the Brigato and La Specula forts, and hearkening, not without some awful pleasure, to the thunder of the cannonade.
These two drawers were carried into the stone-floored workshop, where the bench under the window was covered with an old blanket, another doing duty as cover for the glass tool which had been replaced on the head of the cask. "My word! what a differ there is here," said David, as he glanced round with the drawer in his hands. "What yer put to bed under they blankets, sir?" "Specula, David."
Each of these Specula contains a summary, extracted from the various writings which have reference to the subject of it, and the authors of which Vincent of Beauvais takes care to name.
At length, in 1839, two specula, each three feet in diameter, were turned out in such perfection as to prompt a still bolder experiment. The various processes needed to insure success were now ascertained and under control; all that was necessary was to repeat them on a larger scale.
Halfway down the frail-seeming stem was a light gallery about which hung a cluster of tubes minute they looked from above rotating slowly on the ring of its outer rail. These were the specula, en rapport with the wind-vane keeper's mirrors, in one of which Ostrog had shown him the coming of his rule.
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