Fuel consumption calculating slide rule - comprises fixed and rotary rings mounted on watch face with logarithmic scales

摘要

The watch includes a fixed ring (4a) with a logarithmic graduated scale (6) giving a scale of distance covered, for example in kilometres. This ring is surrounded by a rotating ring (5) with a further logarithmic graduated scale indicating the quantity of fuel used. By rotating the moving scale relative to the fixed scale, the distance covered and the fuel consumed are aligned. The fuel consumption figure may then be read from a small notch (11) in the outer edge (12) of the moving dial revealing the result of the calculation. ADVANTAGE - Calculator is combined with watch face.