A machine for solving spherical triangles, more particularly for finding the position of a ship at sea

摘要

140,441. Le Sort, H. T. M. March 18, 1919, [Convention date]. Spherical-trigonometry calculators.-More particularly for finding the position of a ship at sea, comprises means for calculating, according to Towson's method, i.e.. solving the pole-zenithstar triangle by the means of solving the rightangled triangles formed by dropping a perpendicular from the star upon the meridian, the altitude and azimuth of the observed star from the known data latitude, declination, and hour-angle. The equations involved are of the form Sin a = Cos gamma Sin B which can be expressed thus : 2 Sin a = Sin (# + gamma) + Sin (# - gamma ). As shown diagrammatically in Fig. 1, the shafts a, b are connected to revolution-counters l, m of which the dials are graduated in degrees and minutes of angular measure. The shafts a, b are also connected to two differential gears o, p arranged so that if the counters l, m indicate the angles #, gamma the shafts c, d will rotate an amount proportional to the angles (gamma + gamma), (# - gamma) respectively. The shafts c, d are connected to similar mechanisms i, j as described in Specification 140,442, which enables the driven shafts e, f to rotate through an amount proportional to the sines of the angles (# + gamma), (# - gamma) respectively. The shafts e, f are connected by means of a differential gear q to a shaft g and thereby rotate the shaft g an amount proportional to Sin a; the shaft g acts on a mechanism k similar to the mechanism i, j and thus rotates a shaft h an amount proportional to the angle a which is indicated on a revolutions-counter n. The complete apparatus is shown diagrammatically in Fig. 3, and comprises four appliances R, S, T, and U which are identical to the apparatus shown in Fig. 1. The appliances are combined by connecting the parts that correspond to the same variable, i.e. the shafts 3, 4, and 8 are connected to the shafts 2, 9, and 10, and the shaft 5 is connected to the shaft 6 through a differential gear 18. In operation, the shafts 1, 2, and 7 are rotated to indicate the hour-angle P, the declination D, and the latitude L respectively, the desired values of the altitude H, and azimuth Z will be given on the revolution-counters of the shafts 10, 11. One of the mechanisms 14, 21 may be dispensed with provided that the shafts 24, 25 are connected together.