1. In previous papers I have investigated the wave-making resistance of a ship by comparing it with a certain simple type of pressure disturbance travelling over the surface of the water. In a recent paper on the effect of form and size on the resistance of ships, by Messrs. Baker and Kent of the National Physical Laboratory, reference is made to this point of view. The main work of these authors consists in the examination of model results and the deduction of empirical formulæ of practical value. In addition, they connect the wave-making properties with the pressure distribution and have obtained graphs of the latter for various ship forms under certain conditions; these curves show a range of negative pressure, or defect of pressure, between the positive humps of excess pressure corresponding to the bow and stern. The authors remark that this will have an effect upon the wave-making, but conclude that it is sufficient for their purpose to be able to state that such pressure disturbances, as they have shown to exist when a ship is in motion, will produce waves which will vary more or less in accordance with the theory referred to above.