When, in 1858, the Admiral reached the allotted term of three-score years and ten, yet in perfect health, he executed his resolution of resigning to younger men the posts he held in the active scientific world, and concentrated his attention, at his quiet and literary retreat of St. John's Lodge, near Aylesbury, on reducing for the press the vast amount of professional as well as general information which he had amassed during a long, active, and earnest life: the material for this "Digest" outstanding as the last, largest, and most important part of it. Had he survived but a few months more, a preface in his own terse and peculiar style, containing his last ideas, would have rendered these remarks unnecessary; but he was cut off on the 8th of September, 1865, leaving this favourite manuscript to the affectionate care of his family and friends. By them it has been most carefully revised; and is now presented to the public, especially to his honoured profession, for the benefit of which he thought and worked during the long period which elapsed between his leaving the quarter-deck and his death; as his Charts (constructed from his numerous surveys), his twenty years' Essays in the United Service Journal, his efforts to render his astronomical researches accessible to seamen,—all testify.

Admiral Smyth was what has been called a commonplacer. He had the habit of methodically storing up, through a long series of years, all that could profit the seaman, whether scientific or practical. A collector of coins, and in various ways an antiquary, he knew well, not merely that "many mickles make a muckle," but that it will sometimes chance that the turning up of one little thing makes another little thing into a great one. And he culled from the intelligent friends with whom he associated many points of critical definition which cannot be found elsewhere. Thus, in addition to naval terms, he has introduced others relating to fortification; to ancient and modern arms and armour; to objects of natural history occurring at sea, in travel, &c.: the whole forming such an assemblage of interesting and instructive matter as will prove valuable to both seaman and landsman.

This "Digest" may engage the attention of the naval officer, not merely for the information it conveys, but for the doubts it may raise in matters deserving further research. Independently of the variety of subjects treated, the author's characteristic manner of handling them will make it to his former brother officers a reminiscence of one of the true tars of the old school—the rising generation will find here old terms (often misunderstood by younger writers) interpreted by one who was never content with a definition until he had confirmed it satisfactorily by the aid of the most accomplished of his cotemporaries; the landsman will discover the meaning or derivation of words either obsolete or which are not elsewhere to be traced, though occurring in general literature. To all it is the legacy of an officer highly appreciated by men of science, who on shore as well as afloat fought his way to eminence in every department, and always deemed it his pride that no aim was dearer to him than the advancement of his noble profession.

London, May, 1867.