GB509974A - Improvements in instruments for indicating bearings on maps - Google Patents

Abstract

509,974. Indicating bearings on maps. JACOBS CO., F. L. Oct. 29, 1938, No. 31353. Convention date, June 8. [Class 97 (ii)] A map 21 and two plates 3, 4, each carrying a series of spaced parallel lines are mounted for independent rotation in a frame 1 so that the map 21 may be orientated and the lines on the plates 3, 4, aligned with the bearings of two radio beacons of known position. The position of the instrument is then indicated on the map by the point of intersection of the lines passing through the known positions of the beacons on the map. The latter is carried by inwardly extending plates 20 on a graduated rotatable ring 16. One of the plates 20 has a pin 22 to engage a notch in the map. An inner graduated ring 12 for indicating the angular position of the plates 3, 4, is fixed to the frame 1 by bridge supports 13. The plates 3, 4, and ring 16 have peripheral teeth and are adjusted independently by the knobs 8, 9, 19 respectively. In a modification the map 21 is attached to the frame 1 behind the plates 3, 4. In a further modification a pointer, pivoted beneath the plates 3, 4, and map 21 is connected by flexible shafting to the directional aerial of a radio receiver.