1851 Great Exhibition: Official Catalogue: Class X.: Barton Hugh William
343. WILLIAM, BARTON HUGH, Water foot, Ireland.
An instrument designed to take angles and bearings in the field, and transfer them mechanically to paper, without reading off.
This instrument consists of two rulers, with sights attached to each. These rulers turn on a pivot, and a compass is fixed in the lower valve. It is designed to take angles and bearings in the field, and transfer them mechanically to paper without reading off. It is particularly intended to take the place of Sir Howard Douglas's reflecting instrument, and Schmalcalder's compass and protractor, the offices of all three of which instruments it undertakes to perform.