Items related to A manual of spherical and practical astronomy Volume...
A manual of spherical and practical astronomy Volume 2; embracing the general problems of spherical astronomy, the special applications to nautical ... instruments, with an appendix on the m - Softcover
Synopsis
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1893 Excerpt: ...solely upon the movable one. Thus, to determine the nadir point, having brought the circle division which is nearest to the nadir point reading under microscope A, let the mean reading obtained from all the microscopes be called C„. Bring the micrometer thread into coincidence with its image, and let the micrometer reading be M0, which we shall suppose to be converted into arc by multiplying by the value of a revolution found according to Art. 46 or 47. It is now evident that when the telescope is directed upon a star, if the micrometer reading remains M0 while the thread bisects the star and the circle reading is C", the nadir distance is C--C0, precisely as if the micrometer thread were fixed. But the reading C will, in general, involve an error of runs, to avoid which, set the circle as before upon a neighboring exact division, and let the reading be still called C; then bisect the star with the micrometer thread, and let the reading be M'; the nadir distance of the star will be N'= (C--C0) + (M'--Ma) (190) In practice, this method will be found much simpler than it at first appears. The finder should always be adjusted so that whole minutes in its reading correspond to whole minutes of the principal circle. Then, in all observations of the nadir point, we set the finder to the same exact division; and, in observing the star, we compute its approximate nadir distance to the nearest minute, and set the finder upon this minute. In the above formula, we suppose the micrometer readings to increase with the circle readings. Example.--On May 4, 1856, the telescope of the Meridian Circle of the Naval Academy was directed to the nadir by setting the finder upon 0 0', and the mean of the four microscopes gave the circle reading C0 = 359 59' 54".70...
"synopsis" may belong to another edition of this title.
(No Available Copies)
Search Books: Create a WantCan't find the book you're looking for? We'll keep searching for you. If one of our booksellers adds it to AbeBooks, we'll let you know!
Create a Want
