Two practical measures might go a long way at the moment towards solving some of the questions raised by Captain F. J. Wylie in his paper (Vol. VI, p. 271) and discussed in the last number of the Journal (p. 202). The first is the provision of a suitable plotting device. It should not be too difficult to evolve a mechanism whereby a strip of transparent tracing material is passed across the face of the radar screen by means of two rollers (similar in operation to the echo-sounder paper passing over the plate in the modern sounding machine) in a direction parallel to the ship's course and at a speed representing that of the vessel and proportional to the scale of the radar picture in use. Plotting would be done by marking the ship's position and all other objects on the screen at short intervals and joining the consecutive positions of each object with a line. There would then be a continuous and up-to-date true plot of the area, which would be no more cluttered up with plotting than the actual area was with ships and objects.