Sauzay, A. (Alexandre), 1804-1870 · London, S. Low, son, and Marston · leaf 273
ON OPTICAL GLASSES, 249 closed by a large mirror which is metallic, polished and con- cave, and has in its centre a circular opening, allowing the rays of light to pass through to the eye-lens. At the other extremity is a second concave mirror, of the same metal. … Fig. 62. — GREGORIAN TELESCOPE. To Gregory's telescope succeeded that of Newton (1672), which differs from the former in that the great mirror is not pierced, and that the small one on which it reflects the light is inclined laterally towards an eye-piece placed at the side of the tube of the…
Glass manufacture · Glassware
Internet Archive · Getty Research Institute · Public domain (published before 1931). Free to use for anything.
