Dollond refracting telescope, 1790-1810.
© Science Museum / Science & Society Picture Library
This bras telescope was made by the London instrument makers Peter and George Dollond. It has a 2 3/4 inch lens and is carried on an equatorial mount of the type first introduced by the Sisons family of instrument makers. Used in conjunction with a table, the equatorial stand could be made horizontal using the three adjusting screws and the pair of spirit levels. Once adjusted, objects could be located using the circular setting scales. A telescope of this quality would only have been affordable to a wealthy individual with an interest in astronomy.