File:Astronomy for high schools and colleges (1881) (14763558392).jpg

Identifier: astronomyforhigh00newc (find matches)
Title: Astronomy for high schools and colleges
Year: 1881 (1880s)
Authors: Newcomb, Simon, 1835-1909 Holden, Edward Singleton, 1846-1914, joint author
Subjects: Astronomy
Publisher: New York, H. Holt and Company
Contributing Library: The Library of Congress
Digitizing Sponsor: The Library of Congress

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:
his asidereal stratum, an eye placed somewhere within it will see allthe stars in the direction of the planes of the stratum projected intoa great circle, which will appear lucid on account of the accumu-lation of the stars, while the rest of the heavens, at the sides, willonly seem to be scattered over with constellations, more or lesscrowded, according to the distance of the planes, or number ofstars contained in the thickness or sides of the stratum. Thus in Herschels figure an eye at /Swithin the stratum ahwill see the stars in the direction of its length a &, or height c d,with all those in the intermediate situations, projected into thelucid circle A OBI), while those in the sides mi), nw, will be seenscattered over the remaining part of the heavens M VNW. STRUCTURE OF THE HEAVENS. 481 ** If the eye were placed somewhere without the stratum, at novery great distance, the appearance of the stars within it wouldassume the form of one of the smaller circles of the sphere, which
Text Appearing After Image:
Fig. 135.—herschels theory op the stellar system. would be more or less contracted according to the distance of theeye ; and if this distance were exceedingly increased, the wholestratum might at last be drawn together into a lucid spot of any 482 ASTRONOMY, shape, according to the length, J^readth, and height of the stra-tum. Suppose that a smaller stratum p q should branch out fromthe former in a certain direction, and that it also is containedbetween two parallel planes, so that the eye is contained withinthe great stratum somewhere before the separation, and not farfrom the place where the strata are still united. Then this secondstratum will not be projected into a bright circle like the former,but it will be seen as a lucid branch proceeding from the first, andreturning into it again at a distance less than a semicircle. In the figure the stars in the small stratum pq will be pro-jected into a bright arc P R B P, which, after its separation fromthe circle G B D, unites with it

Note About Images