The contemporary reviews of Maury’s “Physical Geography of the Sea” gave unqualified praise to his style. The _Revue des Deux Mondes_ declared, “Often indeed his powerful imagination makes of Maury a veritable poet, and his descriptions recall involuntarily those stories of the ‘Thousand and One Nights’, which charmed our childhood, where Gulnare pictures for her husband marvellously the mysterious realms of the profundities under the sea”. Humboldt considered it an epoch-making book, and the French scientist Jomard congratulated Maury upon the accomplishment of a “work so difficult, so useful, so laborious”, which he regarded as a true present to physicists, geographers, and navigators as well as to the commerce of all nations. The _Blackwood’s Edinburgh Magazine_ joined in the hymn of praise with the opinion that “the good that Maury has done, in awakening the powers of observation of the officers of the Royal and mercantile navies of England and America is incalculable”, and added that such researches were exercising the most beneficial effect in improving and elevating the minds of seamen everywhere. Some of Maury’s theories, however, were early questioned, especially the one regarding the causes of ocean currents such as the Gulf Stream. He contended that they were set in motion by differences in specific gravity of the water in different places as caused by a disparity in temperature or in saltness. Sir John Herschel had considered that the currents were due entirely to the Trade Winds; and C. Wyville Thomson, who thought that Maury’s theory was ambiguous, was an adherent to the Herschel theory, though his colleague Carpenter was of a different opinion still. “It is now known, however,” writes Sir Willam A. Herdman,[7] “that the Gulf Stream is not an independent phenomenon, but is a part of the general system of surface circulation of the ocean, a system in which the currents, diverted to the east, as a result of the rotation of the earth in their course northwards from the equator, flow clockwise in the North Atlantic around a central, relatively calm area, the Sargasso Sea, in which seaweeds and other floating objects accumulate”. When one considers how science develops, one theory changing or giving place entirely to another as new and wider research is made, such criticisms as those above do not lessen at all the estimation of Maury’s greatness as a pioneer scientist in a comparatively new field of investigation, nor do they at all rob him of the right to be called the world’s first great oceanographer. This is the opinion of a recent authority on the science of the sea, who writes, “Marine meteorology may be said to date from the time of M. F. Maury, U. S. Navy, whose ‘Physical Geography of the Sea’, though out of date as to facts and somewhat fantastic as to theories, remains a model book of popular science, written by a man who was possessed of all the knowledge of his time, and afire with the enthusiasm of research”.[8]