His sagacious suggestion, however, remained entirely unnoticed until revived it would seem independently by Julius Robert Mayer in 1848; while similar, and probably original, conclusions were reached by William Ferrel of Allensville, Kentucky, in 1858. Delaunay was not then the inventor or discoverer of tidal friction; he merely displayed it as an effective cause of change.

He showed reason for believing that its action in checking the earth's rotation, far from being, as Ferrel had supposed, completely neutralised by the contraction of the globe through cooling, was a fact to be reckoned with in computing the movements, as well as in speculating on the history, of the heavenly bodies. The outstanding acceleration of the moon was thus at once explained.

A generation later, Professor William Ferrel, the American meteorologist, who had been led to take up the subject by a perusal of Maury's discourse on ocean winds, formulated a general mathematical law, to the effect that any body moving in a right line along the surface of the earth in any direction tends to have its course deflected, owing to the earth's rotation, to the right hand in the northern and to the left hand in the southern hemisphere.

One party, fitted out in connection with the American Association for the Advancement of Science, was sent to Greenland. Admiral Davis desired to send another, on behalf of his own office, into the central regions of the continent. As members of this party Mr. Ferrel and myself were chosen. At the request of Professor Agassiz one of the assistants in the Museum of Comparative Zoölogy, Mr.