Similar Items

• Description of the improved achromatic telescope : made with brass sliding tubes, by P. and J. Dollond, opticians
  Published: (1800)
• Proposals for making a large reflecting telescope, by Francis Hauksbee
  by: Hauksbee, Francis
  Published: (1715)
• Description of the two feet and half achromatic telescope : Made by P. and J. Dollond, in St. Paul's Church-Yard, London. The object-glass of this Telescope is composed of two glasses, one convex of crown glass, and the other concave of white slint glass; the diameter of the aperture is two inches. The plate represents the Telescope on its stand: AA is the wooden tube 2 1/2 feet long. The tube BB, that contains four eye-glasses, to be used for land-objects; and also the tube C, that contains two eye-glasses for astronomical purposes, are to be serewed into the end of the brass tube D. By turning the button a, this tube moves out of the wooden tube to adjust the eye-glasses to the proper distance from the object-glass, so as to render the object distinct. The magnifying power with the eye-glasses for land objects is near 50 times, and with those for astronomical uses it is 80 times. The stained glass b is applied to the eye-tube C to guard the eye in observing the spots on the sun. This glass must be taken off when the eye-tube is used for any other purposes. The vertical and horizontal motions are given to the Telescope by means of the joints at c and d. Description de la lunette Achromatique de Deux Pieds et Demi, Fait pair P. et J. Dollond, dans la Cimitiere de St. Paul a Londres
  Published: (1775)
• On the power of penetrating into space by telescopes : with a comparative determination of the extent of that power in natural vision, and in telescopes of various sizes and constructions; illustrated by select observations. By William Herschel, LL.D. F.R.S. From the Philosophical transactions
  by: Herschel, William
  Published: (1800)
• An essay on the genuine construction of a standard microscope and telescope : With the application of a prismatic or catadioptric eye-piece to refracting and reflecting telescopes, by which their lengths are much contracted, their fields of view encreased, and their uses greatly facilitated; particularly in the reflector of Cassegrain's form for celestial observations. By B. Martin
  by: Martin, Benjamin
  Published: (1776)