Calculating instrument (maybe wind drift), consisting of a circular, metal disc. Around the outside edge, are black markers that indicate 360°. They are marked with numbers at intervals of 10 (10, 20, 30...). At the centre, is a black and red grid. The edges of the grid are marked by numbers at intervals of 5, from 0 - 60 (0, 5, 10...). These ranges represent miles per hour (marked M.P.H.). Around the grid, are directional markings (N.S.E.W.). Spanning the diameter of the disc, is an adjustable dial. The dial is attached at the centre with a metal pin. There is a "window" at each end through which the degrees on the disc can be seen. One side of the dial has a number scale from 5 - 60 (marked at intervals of 5). This scale is marked in red and labelled: "KNOTS". The other side of the dial has a number scale from 5 - 70 (marked at intervals of 5). This scale is marked in black and labelled M.P.H. Just below the O mark on the disc, is a circular hole.
Instrument [Wind Drift Instrument], 2004.103. The Museum of Transport and Technology (MOTAT).