Three draw telescope with engraved'scale of minutes'

A nickel silver three draw telescope with a dark, mahogany barrel, unsigned, but the 2nd and 3rd draw tubes engraved with a scales of small increments and'Scale of minutes'. It was the Scottish scientist Sir David Brewster who invented the telescope for measuring Angles and Minutes and had a joint patent with instrument maker William Harris to produce / sell such a telescopes in May 1811. Brewster's original design of this type of telescope was engraved,'Scale of minutes divided object glass' and' Scale of minutes single object glass', with internal steel pointers and a pair of parallel fibres. After taking a series of readings from various points, the user could work out the distance and angle of an object. This telescope appears to be of similar construction though how one uses it to its full intention is not known.

Two steel pointers can be seen when viewing through the telescope but there are no fibre lines; one of the small, internal lenses has some scoring to the outside but the telescope gives very clear images when viewed through. Fully open and 9.75? Difficult to date but most likely 1860 - 80.

---