Excerpt from By Starlight and Moonlight With the Warner Swasey Prism Terrestrial Telescope: Some Easy Astronomical Observations This Porro Prism instrument represents the highest development in Terrestrial Telescopes. Its relation to the ordinary telescope is the same as that of our Prism Binocular to the old type of field-glass. It is remarkable for its large field, brilliant illumination and clear definition. The objective is 2 inches in diameter, clear aperture. Two eye-pieces are provided, magnifying respectively 25 and 50 diameters. The telescope tube and the alt-azimuth mounting are made of aluminum. The folding tripod is of carefully selected ash. All are contained in a neat leather-covered carrying case; total weight only twelve pounds. Weight of telescope with its tripod and mounting, apart from case, but six and a half pounds. The high quality of its optical equipment, and the simplicity and adequacy of its mechanical provisions, make it superior to any similar telescope upon the market for the camper, the traveler, the motor-tourist, the surveyor, or the marksman upon the rifle-range. It is especially adapted for porch, seaside and general use. While thus designed strictly as a terrestrial telescope, its purchasers have also found it of much interest and value in the field of amateur astronomy. It is not presented as - in the technical sense - an astronomical telescope; and yet its quality is so superior that its efficiency is actually greater than that of many larger astronomical telescopes heretofore offered to the public. The ease with which it can be moved from place to place in the observation of moon and stars, its sharp definition and breadth of field, combined with the precision and steadiness with which the instrument may be "pointed" and controlled, have brought many expressions of satisfaction from those who having first purchased it as a terrestrial telescope have subsequently tested it in their observations of celestial objects. To respond to the interest and the demand thus indicated, and to illustrate, for beginners, some of the simple astronomical uses of the Warner & Swasey "Prism Terrestrial," this little booklet has been prepared. Our long experience in making "Optik Tubes" of all sizes, from the great Lick and Yerkes Telescopes to the Telescopic Gun Sights, Range Finders, Sextants, etc., used by the Army and Navy, especially qualifies us to develop from both a scientific and practical standpoint, the highest type of Porro Prism Telescope. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.