-
Skip These Ads
-
Skip These Ads|
|
 |
Click here and add this page to your favorites!
|
Encyclopedia Britannica - Main :: NUM-ORC |
|
|
OBSERVATORY . Up to a comparatively recent
Up to about 300 B.C. it can scarcely be said that an observatory existed anywhere, as the crude observations of the heavens then taken were only made by individuals and at intervals, employing the simplest possible apparatus. Thus, according to Strabo. Eudoxus had an observatory at Cnidus. But, when philo
accumulation of facts was found to be necessary before the knowledge of the construction of the universe could advance farther, the first observatory was founded at Alexandria, and continued in activity for about four hundred years, or until the middle or end of the and century of the Christian era. Hipparchus of Rhodes, the founder of modern astronomy, by repeating observations made at Alexandria, discovered the precession of the equinoxes, and investigated with considerable success the motions of the sun, moon and planets. His work was continued by more or less distinguished astronomers, until Ptolemy
With the commencement of scientific studies in Europe in the 15th century the necessity of astronomical observations became at once felt, as they afforded the only hope of improving the theory of the motions of the celestial
series of observations with various instruments, worked by himself and a staff of assistants. In this respect his observatory (Uraniburgum) resembles our modern larger institutions mare closely than do many observatories of much more recent
The instruments employed in observatories have of course changed considerably during the last two hundred years. When the first royal observatories were founded, the principal instruments were the mural quadrant for measuring meridian zenith distances of stars, and the sextant for measuring distances of stars inter se, with a view of determining their difference of right ascension by a simple calculation. These instruments were introduced by Tycho Brahe, but were subsequently much improved by the addition of telescopes and micrometers. When the law of gravitation was discovered it became necessary totest the correctness of the theoretical conclusions drawn
While the necessity of following the sun, moon and planets as regularly as possible increased the daily work of observatories, other branches of astronomy were opened and demanded other observations. Hitherto observations of the " fixed stars " had been supposed to be of little importance beyond fixing points of comparison for observations of the movable bodies. But when many of the fixed stars were found to be endowed with " proper motion," it became necessary to include them among the objects of constant attention, and in their turn the hitherto totally neglected telescopic stars had to be observed with precision, when they were required as comparison stars for comets or minor planets. Thus the field of work for meridian instruments became very considerably enlarged. In addition to this, the increase of optical power of telescopes revealed hitherto unknown objectsdouble stars and nebulaeand brought the study of the physical constitution of the heavenly bodies within the range of observatory work. Researches connected with these matters were, however, for a number of years chiefly left to amateur
special
It would be difficult to arrange the existing observatories into classes either according to the work pursued in them or their organization, as the work in many cases at different times has been directed to different objects, while the organization depends mostly on national and local circumstances. As already alluded to above, one of the principal characteristics of the larger observatories of the present day is the distribution of the work among a number of assistants under the general superintendence of a director. This applies principally to the great observatories, where the sun, moon, planets and a limited number of fixed stars are without interruption being observed, but even among these institutions hardly two are conducted on the same principles. Thus in Greenwich the instruments and observations are all treated according to strict rules laid down by the astronomer-royal, while in Washington or Pulkowa each astronomer has to a certain extent his choice as to the treatment of the instrument and arrangement of the observations. The same is the case with the smaller institutions, in most of which these arrangements vary very much with change of personnel. The way in which the results of observations are published depends principally on the size of the institutions. The larger observatories issue their " annals " or " observations " as separate periodically-published volumes, while the smaller ones chiefly depend on scientific journals to lay their results before the public, naturally less fully as to details. Subjoined is a catalogue of public and private observatories still in activity in 1910 or in existence within the past hundred years. (4f= 1 of long.) (Abbreviations: ap., aperture; equat., equatorial; obs., observatory or observations; o.g., object-glass; phot., photographic; refl., reflector; refr., refractor; s.g., silvered glass; vis., visual; univ., university. Where the names of two makers are given, the first is responsible for the optical, the second for the mechanical part of the instrument.) End of Article: OBSERVATORY If you wish, you can link directly to this article.
<a href="http://jcsm.org/StudyCenter/Encyclopedia/NUM_ORC/OBSERVATORY.html"> OBSERVATORY </a> |
|
|
(Previous) OBSEQUIES (Med. Lat. obsequiae, formed after cl... |
(Next) OBSIDIAN |
Jesus Christ Saves Ministries, P.O. Box 70696, Pasadena, CA 91117JCSM is a 501(c)(3), non-profit organization. Copyright © 1997-present. |
Free & Cheap Cell
Phones |
Cheap Long Distance
Phone Service Carriers |
Talk America Local Phone Service
|
Ztel & MCI - Unlimited Long Distance
Compare
Cell Phone Plans & Companies |
International Calling Cards & Prepaid Phone Cards |
Voice Over IP Broadband Internet Phone
Service | Wireless
Phone Plans & Cheap Cell Phones
|
_____________________________________________________________________________
Online First Aid and CPR Certification . The Online Christ Centered Ministries . The Skeptic's Annotated Bible: Corrected and Explained . The Inerrancy Discussion Board . Free Email Accounts . Home Equity Loans . JasonGastrich.com . The Missions, Apologetics, and Creation Bible Conference . Young Earth Creation Science . San Diego Music Lessons . 10,000 Wise Quotes and Spiritual Sayings . Gastrich.net . Maximizing the Internet: 12 Keys to Success . Louisiana Baptist University . NKJV Web Hosting and Services . Michael Newdow . San Diego Soccer Training . Christian Guitar Lessons . Jesus Christ Saves Ministries . Eternal Security
