Evidence of Undertow from Engineering Practice.

Although In our geological textbooks the undertow has been described as a well known phenomenon, some doubts have been expressed In recent years as to Its reality. This question was first raised by Professor W. M. Davis In 1925 as the result of some observations made by him along the Florida coast. A few years later independent investigations regarding the existence of the undertow were made by Dr. F. P. Shepard and by the writer. Dr. Shepard believes that the undertow, as a current of sufficient velocity to be dangerous to swimmers, Is non-exiatent and that the water carried shoreward by the Incoming waves moves out again in localized currents at the surface.