GB229273A - Improvements in or relating to clocks - Google Patents

Abstract

229,273. Cooke, W. E., (Assignee of Cooke, J. E., Cooke, L. E., Cooke, F. B., Cooke, M. G., Minchin, J. A., and Trigg, D. A.). Feb. 16, 1924, [Convention date]. Sundials; geographical or universal.-Relates to a clock in which the hands are automatically moved to indicate the correct apparent, mean, or standard time by the act of forming an image of the sun on a day chart. A base plate 10, Fig. 1, provided with levelling screws 11 and a spirit-level 12, carries a plate 14 which can be swung laterally over the plate 10 and clamped thereto by a screw 15. The plate 14 carries brackets 16, 17 between which is pivoted a plate 18 which can be clamped at any desired angle on a curved bar 19 and which carries a clock dial 20, Fig. 2, and a gear train 21 - - 24 controlling the clock hands 25, 26. An angle frame 27 is fixed to the gear-wheel 24 and one arm 28 is provided with a pin-hole 29 while the parallel opposite member 30 carries a day-chart 31, Fig. 3, the central point, 32 of which is situated perpendicularly opposite the pin-hole 29, the said chart showing by marks 33 on a curve 34 the angular daily displacement of the sun from its mean position. The equatorial plate 18 is set parallel to the celestial equator by levelling the plate 10 and elevating the plate 18 to make an angle with the plate 10 equal to the colatitude of the clock's station and moving the plate 14 laterally until the image of the sun falls on the correct date-mark, when the clock will indicate the apparent, mean or standard time according to the original setting of the hands 25, 26 in relation to the sun's image at its meridian altitude. The complement of the angle 37 between the plates 18, 14 indicates the latitude of the clock's station, while a compass card or circle 39 may be mounted on the plate 14 so that when the clock is correctly set the N-S line passes through the graduations 0‹ and 180‹ whereby to determine the true bearing of any point within view. Time of sunrise on any day is determined by passing a rod through the hole 29 to rest on the correct datemark and the bringing the rod horizontal with its free end pointing east, while the time of sunset is given by turning the rod to face west. In a modification, the base plate 10, Fig. 5, is circular and a semi-circular support 42 for the equatorial plate 18 is provided, while the sun pointer 46 is formed as a circular band framo the chart 31 being mounted with its central point diametrically opposite the hole 29.