Pelorus

Object ID
001.048.005
Category
Tools and Equipment for Science and Technology, Surveying & Navigation T & E, navigational equipment
Materials
Wood, brass, lead, paint, felt
Artist/Maker/Manufacturer
Thomas S. Negus and his brother John D. Negus started making chronometers in New York, in 1848. They were described as "Probably the most prolific American chronometer manufacturer".
Place Made
New York USA
Description

Pelorus mounted in gimbals in mahogany case. Case is of varnished mahogany. Lid held in place with two tapered dowels mounted in one lip and a similar dowel in opposite lip. These dowels fit into corresponding holes in lower lip. Inside of lid has two green felt lined wooden slats mounted vertically to rest alongside pelorus sights. A 4.5 cm notched bronze mount is mounted on either side to accept the pelorus' gimbals. Each side of case has a single thumb hook that meshes with a slot head brass screw on side of case lid. Penciled along one lip edge are the words, SHIPS HEAD.

The pelorus rests in gimbals on a round blackened bronze circular yoke. The instrument has two sighting gauges that fold down from either side to mesh across pelorus face when not in use. The sighting gauge is a 12.5 cm oval piece of bronze with a slit running vertically. On the inside of this slit are remnants of white surgical tape. The opposite gauge stands 16 cm and has a thin brass wire running vertically through its own vertical slit. These two gauges sit at either end of a bronze shoe that is secured to the centre of the instrument with a double set nut. By loosening the nut the shoe can be rotated. The face of the pelorus has a fleur-de-lis to mark North. The cardinal and inter-cardinal points are marked with their respective letters and the intra-cardinal points are marked with triangles. Around the rim are three concentric circles each marked every ten degrees. The centre of the unit reads, T.S. & J.D.NEGUS NEW YORK. The pelorus is weighted with a circular lead puck.