Transparent course protractor

course protractor

INSTRUMENTS
T. S. & J. D. Negus
USA, NY, New York
paper; celluloid
overall: 4-5/8 x 4-3/4 in.

Course protractor; Transparent course protractor; from the collection of Captain Richard C. Mears (1829-1899); course protractor manufactured by T.S. & J.D. Negus, made either of celluloid or transparent horn, with a compas card printed on it and a length of string coming from the center of the card to be used as the protractor's arm; printed on the front of the paper sleeve in which it is held "TRANSPARENT/ COURSE PROTRACTOR,/ BY/ T.S. & J.D. NEGUS,/ Nautical Instruments,/ 140 WATER STREET, NEW YORK./ IT IS USED/ 1st. Instead of Parallel Rulers, to find on Charts coures/ and bearings, and positions from cross bearings./ 2nd. As an Inspection Table, to turn Compass courses into/ true courses and "vice versa."/ DIRECTIONS SEE OTHER SIDE./ Price $1.50"; printed on back of sleeve "DIRECTIONS./ Place the open centre of the Protractor directly/ over the position of Ship on the chart, then set the/ Protractor true by the parallel lines around its edges,/ cutting or running parallel to some meridian on the/ chart./ With the silk cord draw a North line; then keeping/ the cord drawn to the North, with the other hand turn/ the Protractor, (keeping it central over position,) to the/ East or West for variation and deviation, if any./ Now, stretch the cord to any point, and the reading/ on the Protractor where the cord passes over it will be/ the Compass course to be steered."

2005.34.150