GB579985A - Improvements in or relating to scales and instruments embodying the same - Google Patents

Abstract

579,985. Watches. NEWTON, E. P. (Reece, F. A.). Sept. 7, 1943, No. 14671. [Class 139] [Also in Group XIX] An instrument, by which a pilot can calculate ground speed or distance travelled, has a scale the spacing of whose graduations is infinitely and uniformly variable throughout its length. As shown in Figs. 1, 3, a wrist watch has a post 19 carrying a dial 20 graduated in hours. An elongated minute hand 23 traverses a scale 24 in two hours, the scale 24 being a ring held within the outer edge of the case 15 by a bezel 17. A dial 25 rotatable by knob 29 is mounted on the post 19 and bears a spiral slot 41. A number of spirals identical with the slot 41 are inscribed on a disc 27, mounted on post 19 under dial 25, to represent various speeds. The'points on these spirals equivalent to equal distances are connected as shown at S and Q, Fig. 8, by differently coloured lines 43 and the portions of these lines intersecting and visible through the slot 41 which constitutes a curved scale are the graduations of said scale. The spacing of said graduations can be varied by turning disc 27. In use, the pilot, on starting, sets the zero of dial 25 to coincide with the minute hand 23. When he passes over a landmark he rotates dial 27 by knob 50 until the number of coloured lines 43, between the zero and the minute hand 23, visible through the spiral slot 41 corresponds to the known distance of this landmark from his starting point. The graduation opposite index 42 represents the speed of the aircraft. Conversely the device can be used to calculate distances when the speed is known. Specification 555,155 is referred to.