This portable transit instrument was made for Scott's antarctic expedition of 1901, though there is a note on file to say that there are no obvious mentions of a transit instrument in Scott's narrative of the voyage of the Discovery in 1901-04. The engraving on the telescope, however, which reads 'HO [up arrow - sign of the admiralty] A.64 Ant:Ex. 1901' indicates the link.

The paper label on the box lid reads:
'Dollond & Co. Established 1750
To the Admiralty and Corn Agent to the Colonies
The Royal Life Boat Institute
Optical, Mathematical & Philosophical Instrument Makers'

A transit instrument is a telescope pivoted on a stand so that it can only move in one plane. Normally this would be aligned north-south so that as the Earth turns, every star visible from the latitude of the telescope can be seen to rise and fall over the course of a year. These types of telescopes can be used to create star charts, since every star can be viewed and so plotted. The time at which each star crosses the north-south line, or meridian gives one co-ordinate, the angle the telescope must point at to see it (its angular height) gives the other. It can also be used to find the time by the stars.

This transit instrument has no angle scale so a separate instrument must be used along side this telescope to find the angular height of the star.

The telescope has a focal length of 762mm (30inches) and a lens aperture diameter of 51mm (2inches). The diameter of each setting circle is 127mm (5inches) and the overall length of the axis is 381mm (15inches). The height of the stand is 483mm (19inches).

The fitted box for this telescope contains a stainless steel transit instrument, an eyepiece, a dark slide, a triangular stainless steel base, two conical Y bearings, one striding spirit level, four rag ended securing bolts, two stainless steel nuts, a wing spanner, a lamp and bracket and two tommy bars (one hexagonal section).

The box with accessories are marked AST00987.1-19.