Fecha de publicación: 06/11/1913 Fuente: WIPO "pollen" 5031. Pollen, A. H., and Isherwood, H. March 2, Protractors.-Relates to means for plotting the course of a target ship from a knowledge of its range and bearing angle or compass bearing. A device 2, representing the observing ship, is traversed along a graduated bar 1 by means of a screw 3 rotated from a handle 4 at a rate proportional to the observing ship's speed by the means described in Specification 25,654/08, [Class 106 (iii), Fares &c.]. This device 2 carries fixed to it a disk 5 graduated in degrees and a pivoted disk 6 graduated like a compass card, the first disk being used to give the position of the centrully pivoted and graduated arm 7 when the bearing angle of the target is known and the other when the compass bearings of both ship and target are given. The arm 7 being set to the bearing of the target and the range being known the chart can be pricked at the point indicated. When a series of positions for the target are thus pricked out, a two-disk and pivoted arm arrangement 10, 11, 13 mounted on parallel linkages 9 can be applied to it to determine the bearing of the target's course and its speed. If the ship itself changes its course, the record sheet is unpinned from its board, a pivot pin inserted in a slot at a point distant from the centre of the disk 5 equal to the radius of the ship's turning circle and the paper is then turned about this point through the angle the ship itself turns. Specification 23,872/04 is referred to.