GB680785A - Device for determining the time from the stars - Google Patents

Abstract

680,785. Ascertaining time from stars. MILLIGAN, H. B. Nov. 6, 1950. No. 27098/50. Class 139. [Also in Group XIX]. A device for determining the time from the stars comprises a basic dial provided with a circular scale graduated into twenty-four major divisions and a time dial mounted for rotation relative to said basic dial about the centre of said scale, said time dial being provided with a scale including a reference point and a plurality of major divisions arranged on each side of said.reference point upon an arc of a circle concentric with said first-named scale, an indicator being mounted for rotation relative to said dials about the common centre of said scales, and a sight opening at said common centre. The dial 10, Fig. 1, bearing the circular scale 11 graduated in " hours " has an extension 14 bearing an arrow 16 at the " 24 hour" mark on scale 11. A. dial 23 mounted on tube or sleeve, 18 Figs. 1 and 3, fixed to the dial 10 and having a time scale 24 graduated in " hours up to and from a "12 hour mark and index 26 is rotatable relative to the dial 10 but may be clamped thereto by rotation of a knurled nut 33. An indicator 28 having a radial line 30 is, also rotatable on the sleeve 18 but may be locked by rotation of a knurled nut 36. A ring 37 inside the sleeve 18 supports a pair of cross hairs 38. The indicator 28 embraces the sleeve 18 by a slot 29, Fig. 1,' so that it may be pushed radially inwards to be wholly within the dial 10. In use the star Polaris is sighted through the sleeve 18 by the cross hairs 38 with the arrow 16 pointing as nearly south as possible. The indicator 28 is then moved to point to a chosen star and the position of the line 30 on the scale 11 is read. The dial 23 is then rotated until that graduation on the scale 24 which corresponds to standard time as ascertained from a a timepiece is aligned with the line 30. The dials 10, 23 are then locked by rotating the nuts 33, 36. In this datum position the index 26 on the dial 23 points in the direction''of the position of the chosen star at midnight if Polaris is sighted through the sleeve 18 in the above way, so that if the indicator 28 is at any time moved to point to the' chosen star, with the device held in the above described manner, the reading of the line 30 on the scale 24 indicates standard time. The dial 23 may be adjusted at the end of each third day by reference to an additional scale 40 on the dial 10.