Abstract
It was discussed whether or not the formula √gh derived for the phase velocity of long waves in an ocean with flat bottom, is also applicable to the case of a corrugated bottom configuration. A result was obtained which suggests us that we have to be careful in this application, because the velocity derived from dynamical theory which assumes an undulatory depth distribution is very much different from that computed by the often used formula√gh0, where h0 is an average of the depth over a confined area. In addition it was shown that the undulation of the bottom of the sea accelerates, against general expectation, the phase velocity of long wave train. The larger the amplitude of bottom undulation, the larger is the difference of phase velocity from √gh0 where h0 is the average depth to the bottom.
