student transit theodolite
Date: 1910-1930
Inventory Number: 2006-1-0072
Classification: Theodolite
Subject:
Maker: C. F. Casella & Co. Ltd. (founded 1905)
Cultural Region:
Place of Origin:
Dimensions:
31.5 x 20 x 18.5 cm (12 3/8 x 7 7/8 x 7 5/16 in.)
DescriptionThis altazimuth transit theodolite is made of simple materials for student use--i.e., mostly wood and plastic. The wood appears to be mahogany. The plastic is an early form and is ivory in color at present.
A pair of mahogany triangular uprights support a telescope and 360° protractor. The protractor is divided 90°-0°-90°-0°-90° every 1°. A clear plastic strip carries the index marks. The telescope has a black-metal tube assembly and can rotate a full 360° on its axis (i.e., it can transit). A wood block attached along the tube as two holes, into which a bubble level was probably once fixed. It is currently missing. The axis is made of steel in brass bushings. A spring holds the telescope firmly to the left. There is a brass locking screw.
The uprighs are mounted on circular disk of mahogany which rotates over a horizontal, plastic circular protractor divided 0°-360° every 1°. There is an index mark on a plastic rectangle affixed to the rotating disk. The brass locking screw has a butterfly head and a long shaft that touches the central rotational axis.
On the outside of the uprights there is a bubble level on one side and a trough compass on the other. The compass has no calibrations aside from the North-South indices. The compass housing is also wood.
The entire theodolite described so far is mounted over a triangular plank of wood and turns freely around the central axis on a fitting that is independent of the azimuth bearing. Another long brass locking screw with a butterfly head secures the orientation of the top to this base. The triangular plank rests on three brass leveling screw feet. The feet sit on a three-legged wooden footing.
The theodolite is housed in an upright rectangular pine box whose door opens to the left on two hinges. There are two holes in the top of the box. Each end of a rope handle is inserted in one of the holes and a knot tied in its end.
A pair of mahogany triangular uprights support a telescope and 360° protractor. The protractor is divided 90°-0°-90°-0°-90° every 1°. A clear plastic strip carries the index marks. The telescope has a black-metal tube assembly and can rotate a full 360° on its axis (i.e., it can transit). A wood block attached along the tube as two holes, into which a bubble level was probably once fixed. It is currently missing. The axis is made of steel in brass bushings. A spring holds the telescope firmly to the left. There is a brass locking screw.
The uprighs are mounted on circular disk of mahogany which rotates over a horizontal, plastic circular protractor divided 0°-360° every 1°. There is an index mark on a plastic rectangle affixed to the rotating disk. The brass locking screw has a butterfly head and a long shaft that touches the central rotational axis.
On the outside of the uprights there is a bubble level on one side and a trough compass on the other. The compass has no calibrations aside from the North-South indices. The compass housing is also wood.
The entire theodolite described so far is mounted over a triangular plank of wood and turns freely around the central axis on a fitting that is independent of the azimuth bearing. Another long brass locking screw with a butterfly head secures the orientation of the top to this base. The triangular plank rests on three brass leveling screw feet. The feet sit on a three-legged wooden footing.
The theodolite is housed in an upright rectangular pine box whose door opens to the left on two hinges. There are two holes in the top of the box. Each end of a rope handle is inserted in one of the holes and a knot tied in its end.
Signedlogo on the vertical circle: CASELLA / LONDON
on the vertical circle: MADE IN ENGLAND
on the vertical circle: MADE IN ENGLAND
FunctionTheodolites are used to measure horizontal and vertical angles.
Curatorial RemarksThe pine box might be a replacement.