POWERHOUSE COLLECTION

Telescope made by Dudley Adams, England

Object No. 2005/134/1

Small reflecting telescopes were popular in the 18th century. James Cook used one to observe the 1769 transit of Venus from Tahiti. This fine example is by a respected instrument maker who was from a well-known family of instrument makers. It is the first 18th century reflecting telescope in the collection. The Dudley Adams telescope demonstrates many important aspects of the early history of the telescope, especially reflecting telescopes that have now grown into giants like the twin Keck telescopes with 10-metre diameter mirrors and the two Gemini telescopes with 8-metre mirrors. The first known reflecting telescope was made by the English scientist Isaac Newton whose second telescope was shown at a meeting of the Royal Society in London in 1672. The telescope has primary and secondary speculum metal mirrors as the technique of depositing silver on glass was not perfected till the 1850s. It is of the compact Gregorian design with a concave ellipsoidal secondary mirror reflecting light to an eyepiece through a hole in the primary. This design was proposed by James Gregory in 1663, five years before Newton built his first telescope. Small brass Gregorian telescopes were popularised by the famous maker James Short from about 1740 to his death in 1768. Short sold his telescopes to those who could afford his high prices. This telescope though by a different maker is of a similar design to a typical one by Short including the simple azimuth mounting. This mounting adapts well to terrestrial use, but not so well to any attempt to use the telescope for serious astronomical research.