Register to commemorate its heritage values. During the second half of the 19th century the nation's first astronomical groups and societies were established and a strong community of amateur astronomers and telescope makers emerged. The amateur practitioners funded their own facilities and made an enormous contribution to astronomy in Australia. John Tebutt was one of the most significant of these amateur astronomers. Inspired to pursue astronomy by his observation of the spectacular Donati's comet in 1858, Tebutt became internationally acclaimed in 1861 when he became the first person in the world to discover the "Great Comet". Tebutt established an observatory at Windsor in 1864 and continued to make important observations in the southern skies "including lunar occultation of stars, eclipses and shadow transits of the satellites of Jupiter, the position of minor planets and double and variable stars". Once again this pioneering observatory, "Peninsular House" is listed on the State Heritage Register. Ken Beames who designed and constructed the Observatory complex at Linden was part of this strong tradition of amateur astronomy of the late 19th and early 20th century. As historian of astronomy in Australia Wayne Orchiston points out the amateur cohort of astronomers fall into 3 categories:"apprentices, journeymen and masters. Apprentices are just beginning their astronomical careers, while masters are those acknowledged experts who are able to communicate effectively with professional astronomers in their own chosen fields of expertise. Kenneth Beams was very definitely a master". Unlike most other amateur astronomers Beames' field of interest was in the design and construction of telescopes and optical instruments rather than the observation of the night skies. In fact during the 1930s, 1940s and 1950s Beams was one of the few if not the only amateur or professional astronomers making telescopes and other optical instruments for astronomy in NSW. In a newspaper article from 1970 Beames noted that he had made in excess of 450 telescopes ranging from 6 inch to 24 inch instruments. This is unusual during the mid decades of the twentieth century when most astronomical instruments were imported from Britain, Europe or America. Although not a professional astronomer, Beames' work making telescopes and other instruments has been praised by both amateur and professional astronomers as masterpieces of craftsmanship and engineering which have contributed to the development of the field in NSW and Australia. The 24 inch reflector telescope Beames completed in 1939 was the largest amateur or professionally