GB189709600A - Improvements in Angle and Position Finders. - Google Patents

Abstract

9600. McCombie, T. G. FitzG. April 15. Position-finders; telemeters &c.- The instrument is for determining the position of a ship on a chart by observation of three known objects, for determining the position in which buoys should be placed, plotting and transferring angles, &c. In the form shown, to a slotted circle e, graduated if desired, is fixed an arm a, the edge of which is radial and which carries a half-silvered horizon mirror f, Fig. 2A. The circle is fitted with a notched semicircular plate i for exact determination of the centre, and two arms b, b, with radial edges, are pivoted in the centre and carry pins b<1>, b<1> which may be clamped in any position by slides e and screws e<1>. A slotted arm d pivots about a point on the circumference of the circular slot and carries a perforated index mirror h. The arm is flexible so that it can be sprung over either of the pins b<1>. By engaging the arm d with each arm b in turn and bringing two known distant objects as seen by reflection into line with a third object seen directly, the arms will be set at such angles that when the instrument is removed to the chart and the arms are made to cut the distant objects the notch of the plate i gives the exact position of the ship. By graduating the arms, distances may be read off. A modified form, with two arms d pivoted on a and having mirrors parallel to their edges, is described.