Baker refracting telescope of 1 3/16- inch aperture and 18 inch focal length by J. Sisson, London, on an adjustable equatorial mounting with a flat base stand and wooden case [RAS No.20]. Presented to the Royal Astronomical Society around 1869 by Baker?

Dated to the middle of the seventeenth century, this small brass telescope was made in London by either Jonathan Sissons or his son, Jeremiah. The instrument has a 1¼-inch lens and is carried on an equatorial mount of the type first introduced by the Sissons. Used in conjunction with a table, the equatorial stand was made horizontal using the three adjusting screws and the pair of spirit levels. Once adjusted, objects could be located using the circular setting scales and the naked-eye sight that is folded down in the photograph. A telescope this quality would have only been affordable to wealthy individual who had an interest in astronomy.