Polygonal telescope

The design of this telescope, with its slightly tapering decagonal mahogany barrel, is characteristic of those produced in the 18th century for use on board ship. The barrel was designed for strength, since the techniques for manufacturing strong round barrels were not well developed at this time. The other fittings are brass and include a single draw tube and sliding eyepiece and objective lens covers. The objective lens is achromatic, making this quite an early example of an achromatic telescope, for which the London instrument making firm of Dollond held the patent until the 1770s.

The name 'Jno. Miller HYTHE 1781' is inscribed on the draw tube and probably refers to the original owner. The maker's name is inscribed on the objective lens cover as 'DOLLOND LONDON'. A similar telescope appears in a portrait of Captain Sir Edward Vernon (1723-94), BHC3069.

Object Details

ID: NAV1483
Collection: Astronomical and navigational instruments
Type: Polygonal telescope
Display location: Display - Maritime London Gallery
Creator: Dollond, Peter
Date made: circa 1770
People: Miller, John
Credit: National Maritime Museum, Greenwich, London
Measurements: Length: 660 mm (closed), 734 mm (open to stop line); Diameter: 38-43 mm (barrel), 48 mm (max)