The “real” inverted image of the object formed at m by the object-glass is viewed by the magnifying lens B, the magnifying power being equal to the ratio between the focal lengths of the lenses A and B. 1), of long focus, while the eyepiece, B, is also a convex lens, but of short focus, the two being placed at a distance slightly less than the sum of their focal lengths. The simple refracting telescope has for an objective a large convex lens, A (fig. Telescopes are classed as refracting or reflecting, according as the objective is a lens or a speculum. The optical parts are usually set in a tube, and this is so arranged that the distance between the objective and the eyepiece can be adjusted to give the most distinct vision. The telescope consists essentially of two members: one, the objective, a large converging lens, or a concave mirror (technically speculum), which forms an optical image of the object the other, the eyepiece, a small lens or combination of lenses, which magnifies this image. It originated in the first decade of the seventeenth century, apparently earliest in Holland but Galileo in 1609 independently invented the form which bears his name, published it to the world, and was the first to apply the instrument to astronomical observation. To slide or pass one within another, after the manner of the sections of a small telescope or spyglass to come into collision, as railway cars, in such a manner that one runs into another to become compressed in the manner of a telescope, due to a collision or other force.Īn optical instrument by means of which distant objects are made to appear nearer and larger. To shorten or abridge significantly as, to telescope a whole semester's lectures into one week. To cause to come into collision, so as to telescope. Its essential parts are the object glass, or concave mirror, which collects the beam of light, and forms an image of the object, and the eyeglass, which is a microscope, by which the image is magnified. ☞ A telescope assists the eye chiefly in two ways first, by enlarging the visual angle under which a distant object is seen, and thus magnifying that object and, secondly, by collecting, and conveying to the eye, a larger beam of light than would enter the naked organ, thus rendering objects distinct and visible which would otherwise be indistinct and or invisible.
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