A fine early English telescope or 'spyglass', almost certainly made in London in the early 18th century

112 x 34mm (4.4in x 1.3in), lignum vitae body tube in two parts; brass lens holders with sliding covers; bi-convex object glass and plano-concave eyepiece lens, held in place by brass rings.

Lignum vitae telescopes (also known in the period as 'prospect glasses', 'perspectives', 'optics', 'opera glasses' or 'spyglasses') were extensively marketed in the early years of the 18th century, though surviving examples are rare.

The most common design is longer, typically just over 6 inches long (see, for example, Science Museum inv. no. 1918-142). The largest we have seen is 10 inches (Louwman Collection No. 169). Smaller instruments such as this are exceptionally scarce. These are amongst the very earliest 'pocket' telescopes – comparable to or smaller than the 'Little Perspective' advertised by John Yarwell on his 1683 trade card.

Although these instruments are always unsigned, we can attribute them to the group of instrument makers/retailers who flourished in the early-18th century, benefitting from increased public interest in natural philosophy and the new consumer markets of the period. The best known example of this trend is George Willdey, who was apprenticed to the optical instrument maker Yarwell but by about 1710 was selling a wide range of goods, including maps, optical instruments, toys, china, glass, and earthenware. A diminutive 'spyglass' such as this would likely have been one of his most popular products, combining utility (for example in navigation) with learned pleasure.

The telescope is in excellent condition, and produces a good image with low magnification and a limited focal range. As with other examples we have disassembled, the objective lens has a distinctive green tinge, perhaps indicating crown glass, and the eyepiece lens is entirely clear, perhaps an example of the then-new flint glass favoured that was beginning to be favoured in optical instrument manufacture.