Identifier: americanaunivers15beac (find matches)
Title: Telescope in Yerkes Observatory, The Americana : a universal reference library, comprising the arts and sciences, literature, history, biograhy, geography, commerce, etc., of the world
Year: 1903 (1900s)
Authors: Beach, Frederick Converse, 1848-1918 Rines, George Edwin, 1860- Scientific American, inc
Subjects: Encyclopedias and dictionaries
Publisher: New York : Scientific American compiling dept.
Contributing Library: University of California Libraries
Digitizing Sponsor: Internet Archive

View Book Page: Book Viewer
About This Book: Catalog Entry
View All Images: All Images From Book
Click here to view book online to see this illustration in context in a browseable online version of this book.

Text Appearing Before Image:
FiG. 7.— Reflex Zenith telescope. curate support for these pivots, east and west,carrying the tube so that the movement of thetelescope is in the true meridian only. Inthe exact focus of the telescope a fixedsystem of wires is placed. The best ma-terials for this purpose are taken from thecocoon of the field spider, the web beine but I
Text Appearing After Image:
D r: -1 TELFORu s-oVt of an incli in diameter. These verticalspider webs arc equally spaced and so adjustedinat the central wire is exactly in the opticalaxis of the telescope as measured east and west.A horizontal wire is adjusted exactly in theoptical axis as measured north and south. Par-allel to these central wires there are two mov-able wires, one horizontal and one vertical, eachgoverned by a micrometer screw. In measuring transits of stars for determin-ing right ascensioi?, or for time, the telescope, bymeans of the graduated circles, is set to thedeclination of the star required, and when thestar appears, its transit across each of the wiresis recorded on a chronograph, by the observertapping an electric key. In determining declina-tions, the telescope, by means of the graduatedcircles, is set to the approximate declination ofthe star to be observed, and when the star ap-pears at the edge of the field, the observer care-fully adjusts the telescope until the star seems and the

Note About Images