A new type of parallel ruler on rollers, devised and patented by Mr. Ian A. McIntosh of Sydney, deserves the attention of marine navigators. The new ruler is apparently similar to the brass-roller type used in the Navy, but it has the great advantage of omni-directional mobility. It also has much easier manœuvrability than the parallel rules used in the Merchant Service, known as Captain Field's or the ‘walk-about’ type.