Traverse-board

A piece of shaped board, one portion showing a square surface, the other circular; the square having a line each for the four hours of the watch acro it; all being perforated with numerous holes, say 1 to 12 for the insertion of pegs to mark the number of miles sailed during each hour. The circular part is marked with the rhumb-lines of a compa , each line being holed so that every half hour or hour the course for that time is indicated by the pegs inserted. From the traverse-board, at the end of the watch, averages of the course and speed are computed, for noting them on the log-slate, or for entry in the log book.