This telescope is believed to be made by William Robertson, although James Gregory invented this design of reflecting telescope in 1663. It comprises a primary concave mirror with a central hole and a smaller secondary concave mirror which share a common focus. The image is viewed through the hole in the primary mirror using an eyepiece lens. This telescope may be asociated with Dr Stephen Demainbray (1710-1782), a famous science lecturer of the 18th century.
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