Open AccessMemorandum on the Kew heliograph
Author(s) -
C. Chree
Publication year - 1916
Publication title -
proceedings of the royal society of london. series a, containing papers of a mathematical and physical character
Language(s) - English
Resource type - Journals
eISSN - 2053-9150
pISSN - 0950-1207
DOI - 10.1098/rspa.1916.0006
Subject(s) - eyepiece , observatory , telescope , dome (geology) , schmidt camera , optics , refracting telescope , art , physics , geology , astronomy , paleontology , lens (geology)
The Report of the Kew Committee, presented to the Council of the British Association June 27, 1865, describes the construction of the apparatus as follows:— “The apparatus suggested by Sir John Herschel for photographing the spots on the sun's disc is progressing under the superintendence of Mr. Warren De la Rue. The Solar Photographic Telescope is promised by the maker complete in three months. . . . The diameter of the oldest glass is 3·4 inches, and its focal length 50 inches; the image of the sun will be 0·465 inch, but the proposed eyepiece will, with a magnifying power of 25·8 . . ., increase the image to 12 inches. . . . The object glass is under-corrected in such a manner as to produce the best practical coincidence of the chemical and visual foci... It was originally intended to place the telescope in an observatory 12 feet in diameter, provided with a revolving roof... It has, however, been found possible to somewhat alter the construction of the tube, so as to reduce its length sufficiently to allow of the telescope being placed under the dome of the Kew Observatory, which is only 10 feet in diameter.”