GB124329A - Improvements in or relating to Instruments for Calculating a Ship's Position at Sea. - Google Patents

Abstract

124,329. Bain, J. May 27, 1918. Plane-trigonometry calculators.-Relates to apparatus enabling the problems dealing with observed data and solved by navigators by means of the traverse table to be computed in a graphical manner, more especially those concerning ship's distance from, and position with respect to, sighted terrestrial objects, and also those involved in the calculation of ship's position from observed and calculated altitudes by position-line methods. A base a, having a hinged cover k, carries fixed beneath an annular rim c a disk b divided into squares by two series of equidistant lines parallel to two diameters at right-angles, of which one diameter d, called the N-S line, extends across the annulus, while the other diameter e is termed the E-W line. Arranged to be adjusted angularly over the disk are a transparent dial g, Fig. 3, and a separate graduated radial arm h, upon which the scale agrees with the scale of the squares upon the disk. The dial is graduated angularly in degrees in the quadrant in the same manner as a compass dial, is adapted to bear pencil markings, and, together with the arm, fits over a pivot j secured to the disk and its base. Examples of the use of the apparatus in calculating ship's position by Sumner and Marcq St Hilaire methods are given in the Specification, and also of the calculation of distance and course with respect to an observed light.