File:Astronomy for high schools and colleges (1881) (14577161428).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:
to r= May 25, 11 13 12*.6, T - To = 13 11 13 12«-6■= IS*-467. Hence we have dT (T- AT„ = - y;,) = AT =T =T = + 16 13»5 50 •03 ll^ 15 812« •47•60 10 58« 4* .13 But in this example the rate is obtained for one true sidereal day,while the unit of the interval 13-467 is a sidereal day as shown bythe clock. The proper interval with which to compute the rate inthis case is V6^ 10 58 4=^-13 = 13-457, with which we find Aro= — 16° IS--SO dT X 13-457 = + l* 4^-98 AT = — IS 8^52 r = ll 13 12^-60 r=1058 4^.08 This repetition will be rendered unnecessary by always giving the ratein a n7iU of the clock. Thus, suppose that on June 3, at 4 11 12*- 35by the clock, we have found the correction -1- 2 10^-14; and onJune 4, at 14 17* 49\82 we have found the correction -;- 2^ 19*-89;the rate in one hour of tie clock will be 74 ASTBONOMY. § 4. THE TRANSIT INSTRUMENT. The meridian tra/nsit instricment^ or briefly tlie ^ ^ tran-sit, is used to observe the transits of the heavenly bodies.
Text Appearing After Image:
Fig. 28.—a transit instrument. and from the times of these transits as read from theclock to determine either the corrections of the clock orthe right ascension of the observed body, as explained inChapter I., § 5. THE TRANSIT INSTRUMENT. lb It has two general forms, one (Fig. 28) for use in fixedobservatories and one (Fig. 29) for use in the field. It consists essentially of a telescope T T (Fig. 28)mounted on an axis Y V 2X right angles to it.

Note About Images