Dromoscope

The stated purpose of this instrument is "to determine without calculation the arithmetic mean of two compass readings relating to corresponding inclinations, and also to indicate either amplitudes of the ship's azimuth relating to certain settings of the control compass, and constant azimuth corrections for all geographical latitudes or to indicate definite deviations of a steering compass".


Has scales by which coefficients B, C, D & E can be set, also the variation. There are two graduated dials, one on the front with two pointers, the other on the back with one pointer. When all coefficient scales are set to zero the two points move in unison and correspond at any point around the two dials. When scales are set to represent the coefficients of a vessel and the front pointer set to any course, the rear one appears to show the deviation pertaining to that course.

Contained in fitted wooden box.