William Harris and Son Theodolite
A fine example of a plane theodolite signed on the silvered compass dial " W. Harris and Son 50 Holburn London".    

Harris and Son operated from this address between 1840 - 1855.

The original box has the Harris Trade Label and appears to be made out of pine and is quite light compared to other manufacturers boxes in my collection which are generally made from mahogany.The horizontal circle and vertical half circle are divided into degrees with both verniers reading to 3 minutes of arc.

The theodolite only has one long eye piece, by design, to give an erect image.

The telescope section is fitted with a brass screw on cap to cover and protect the cross hairs when the eye piece is not attached.

The method of focusing of the telescope is by a slide arrangement and not rack and pinion which is usually the mechanics for telescopes.

The original key to lock the box and what appears to be the original horn magnifier to read the verniers are included.

A label attached to the box shows that W F Stanley adjusted the theodolite in 1939.

The instrument has had very little use as there is really no sign of wear especially where one would expect to find wear on the telescope at the slide adjustment.

I suggest that this theodolite is circa 1840 as other theodolites by William Harris and Son, researched on the WWW, appear to be more refined with vernier readers, four foot screw base and rack and pinion focusing.