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Knight's Mechanical Encyclopedia (ed. Knight), A. (search)
y Eratosthenes, the originator of astronomical geography; by Hipparchus, the father of mathematical astronomy; and by Ptolemy, the astronomer, A. D. 150, whose system was accepted down to the time of Tycho Brahe, A. D. 1582, and until Copernicus, Kepler, and Galileo revived the true views of Aristarchus, the heliocentric theory promulgated nearly two thousand years before. Armillary sphere. E. The earth. a. Hour circle. b. North pole of the heavens. c. Arctic circle. d. Tropiclength of the telescope is equal to the sum of the focal distances of the two lenses, and the magnifying power is equal to the focal length of the object-glass divided by the focal length of the eye-glass. This telescope was first described by Kepler in his Dioptrice, 1611, but does not appear to have been executed till 20 or 30 years later. Cooke's telescope. A large instrument of its class was mounted at York, England, by Cooke. See Fig. 401. It is mounted equatorially on the Ger
Knight's Mechanical Encyclopedia (ed. Knight), L. (search)
rta is said to have hastened his death, which happened in 1615, by the fatigue and anxiety incurred in supporting his claims. Galileo had a hint of the invention, studied it out, and made a telescope which he soon put to use. See telescope. Kepler (1571 – 1630) was, perhaps, the first to state with precision the effects of lenses in making the pencils of light converge or diverge. He showed that a plano-convex lens makes rays that were parallel to its axis to meet at the distance of the dnequally convex. As the sum of both the diameters is to one of them, so is the other to the distance of the focus. The rule for convex glasses is applicable to concave, with the difference that the focus is on the contrary side of the glass. Kepler, in his Catoptrics, explains the rationale of the system of lenses in a telescope. Scheiner constructed one on this principle in 1630. His description is as follows: If you insert two similar lenses (that is, both convex) in a tube, and place y
Knight's Mechanical Encyclopedia (ed. Knight), T. (search)
y seen, so that its true character was not at first recognized, — the solar spots, and the crescent form of Venus. As early as November, 1610, Galileo wrote to Kepler that Saturn consists of three heavenly bodies in contact with each other. In this observation there was the germ of the discovery of Saturn's ring. Hevelius deslso noticed that spots which he had observed disappeared and returned again, and these phenomena taught him the rotation of the sun, which had been conjectured by Kepler before the discovery of the spots. The cycle of admirable discoveries, which scarcely occupied two years, was completed by the observation of the phases of Venusecrated ground, or to have a monument. The nineteenth century has attended to the latter duty. The eye-glasses of the Galilean telescope were double-concave. Kepler first pointed out the possibility of making telescopes with two convex lenses. Scheiner, in 1650, reduced it to practice. De Rheita made one with three lenses;
Knight's Mechanical Encyclopedia (ed. Knight), W. (search)
The writer still recollects one form in which the bars of a revolving reel were furnished with cloths and rotated by a hand-crank, the concern being six or seven feet long and having its bearings in posts of a frame standing upon the barn floor. It is among the histories of the machine that when it was introduced in Scotland, certain sensitive persons pronounced it an impious device, as it raised a wind when the Lord had made a calm This is another inflection of the old opposition that met Kepler and Galileo. Winnowing in Egypt (1500 B. C.） Fig. 7259 illustrates a machine, still in use, invented by Gooch of Northampton, England, in 1800. It embraces the important features of the more modern machines: the rotating fan, the shaking-riddle, and sieves for sorting the grain and separating extraneous matters. See also fanning-mill. English winnowing-machine. Winze. （Mining.) a. A shaft sunk from one level to another for communication or ventilation. b. A wheel and a