GB155304A - Navigator's instrument - Google Patents

Abstract

155,304. Tucker, R. W. July 30, 1919. [Convention date]. Departure rules.-A base 1 has a groove 2 in which is slidably mounted a graduated bar 3 to which is pivoted at 5 a graduated bar 4 having a slot 6 which passes over one of two pins 7 carried by the base 1, the pins being equidistant from the median line of the bar 3. A protractor 11 is also rotatably mounted on the pivot 5 which has an upper plain portion 5<b> passing through the bar 4, a plain portion of reduced diameter passing through the protractor and a threaded portion 5<a> engaging in the bar 4, so that the protractor can be clamped by screwing down the pivot. The units of the graduations on the bars are each equal in length to half the distance between the pins 7. The bar 4 carries sights 9, 10, and also has a pin 17 adapted to be inserted into one of a number of holes 18 the distances of which from the median line of the bar 3 are definite fractions of the distance 5-17. The instrument is used for the usual departure measurements, and also if the course of the ship &c. is known the protractor 11 enables the bearing of an object to be determined so that the position of the observer can be found when the distance of the observed object is known.