The telescope is one of the most important inventions, and yet we really have no idea when the first telescope was produced. 1608 is frequently given as the date of invention,
NAME: The Telescope, A Short History
CLASSIFICATION: Book reviews
AUTHOR: Richard Dunn
BINDING: Hard back
SUBJECT: Telescope, radio telescope, radar, radio arrays, reflecting telescope, naval telescope, infrared, HST
DESCRIPTION: The telescope is one of the most important inventions, and yet we really have no idea when the first telescope was produced. 1608 is frequently given as the date of invention, but there is evidence that the design goes back into ancient history. The earliest telescopes were probably carried broken down. A piece of leather was used to form a tube, fastened by thongs and containing one or two simple lenses made by polishing rock crystal. Some early telescopes may have used a wooden tube, but both types would have been unable to adjust by moving a lens relative to a second lens. The survival of crystal skulls gives an indication of the sophistication achieved in ancient civilizations in working natural crystal where today we would cast and polish glass, applying coatings to enhance performance of the resulting lenses. Fragments of written history, and some evidence of navigation instruments from the period of ancient Greece suggest that an instrument was available to bring distant objects closer. It is now clear that the capabilities of the telescope could have been available more than 8,000 years ago but as no complete instrument has so far been discovered we do not know whether early optical devices really took the form of the 17th Century telescope and we have no idea of their effectiveness. The author has covered some of the earliest suggestions, but this is primarily a history of some 500 years of development from relatively simple optical devices to the latest astronomical telescopes on the ground and in orbit that are broadly described as radio telescopes. There is good illustration, including full colour images to reinforce the very readable text. The author has followed the dual strands of telescope development for astronomy and for terrestrial employment. He describes how astronomy required light gathering and focal length capabilities that were beyond the original dual lens design that eventually required a tube that was difficult to mount and use. The personalities involved in telescope design and use are covered. As the telescope was a valuable item of equipment for sailors, they required instruments that could be carried aloft in the rigging and used to focus on objects at various distances. For them, the instrument became a true telescope because it comprised a number of nested tubes that could be telescoped down from full length to a compact length for carrying when not in use. The microscope developed as a bench tool for laboratory use, employing a rotating array of lenses to provide a choice of magnification without requiring the total length of the device to alter, allowing a user to sit at a table of bench while using the device. The author has also covered the development of field glasses and binoculars that provided easy to use optical devices that are compact and provide stereoscopic vision, together with the stereoscopic range finder that assist military gunnery direction before the advent of radar. The use of radio telescopes has transformed astronomy, although many amateur and professional astronomers still use telescopes and binoculars and the integration of telescopes and computers has taken the telescope into new levels of capability. Since the first telescopes were sent into orbit, it has become possible to build ever more powerful devices that operate outside the distortions of the atmosphere and the pollution of lights. The author has provided a comprehensive history within current knowledge and this has produced a fascinating book that will appeal to a wide readership and inspire new generations of telescope user.