LONDON.- A rare and impressive Benjamin Martin Planetarium is the top lot at Bonhams Important Instruments of Science & Technology sale on 31 October in London. It is expected to fetch £80,000-120,000.

This rare, philosophical instrument cleverly demonstrates the movement of the earth and alternatively, the orbits of the then known planets around the sun by use of a hand-cranked geared mechanism. Signed by its maker, Benjamin Martin of London, one of the leading instrument makers in London in the 18th century, the planetarium is a fine working example of the exquisite output from his workshop in Fleet Street. It dates from 1765-70, during which time Martin received a commission from Harvard University, Massachusetts, to produce a collection of scientific instruments. The international recognition of Martin’s work further underlines his lasting significance – many of his models were reproduced into the Victorian era.

Bonhams Science and Technology specialist, Jon Baddeley said: ‘This extraordinary example of Benjamin Martin’s work was truly multi-functional and ahead of its time. Made in the age of Enlightenment, these unusual and rare instruments were often used by the erudite upper classes who were always looking for ways to expand their knowledge of the world around them and share this scientific information at social gatherings.’

Elsewhere at auction, highlights include:

• A Rare Pair of Vincenzo Coronelli 18 ½ inch Terrestrial and Celestial Globes on Stands, Italian, published 1696, estimated at £100,000-150,000

• A Three-Rotor Model 1 Enigma Cipher Machine, German, 1933, estimated at £60,000-80,000.

• A Magnificent Richard Glynne Gilt and Silvered Brass Horizontal Sundial, English, circa 1725, estimated at £25,000-35,000