The author of “The Light of Navigation,” published in 1612, remarks that among other things the “seafaring man or pilot” ought to know how to reckon tides, “that he may knowe everie where what Moone maketh an high water in that place, that when he would enter into any Haven or place, where he can not get in at lowe water, then he may stay till it be half flood.” He ought to know also the direction of the tide, and complains that some “upon pride and unwillingnes, because they would keepe the art and knowledge to themselves,” “will not suffer the common saylers to see their work.” [Illustration: “THE PERSPECTIVE APPEARANCE OF A SHIP’S BODY, IN THE MIDSHIPS DISSECTED.” This ingenious drawing, which gives the reader a good idea of the interior of a seventeenth-century ship, is among the Pepysian MSS. in Magdalene College, Cambridge, and entitled “Mr. Dummer’s Draughts of the Body of an English Man of War.” Edward Dummer was assistant shipwright at Chatham. Pepys described him in 1686 as an “ingenious young man.”] In the seventeenth century the lieutenant was still not necessarily a seaman. He was a well-bred gentleman, knowing how to entertain ambassadors, gentlemen, and distinguished visitors received on board. He was capable of being sent as a responsible messenger to important personages, and was, in short, of far more use as a social instrument than as a naval officer. During the Commonwealth soldiers again became sea-commanders, and the names of Blake, Monck, and Popham will instantly leap to the mind. Up till the time of Charles II the sea service had not always enjoyed the dignity of being deemed a profession worthy of gentlemen. There were, of course, exceptions; but as a general rule this was the case. But, thanks to the example of the Duke of York, afterwards James II, the Navy during the time of his brother Charles II became fashionable--too fashionable, in fact; for numbers of gentlemen got themselves promoted to the rank of ship’s captain while knowing very little indeed about ships and their ways. One has only to read through some of Mr. Pepys’ remarks to appreciate this unfortunate condition of affairs.