In those early days the population kept within easy reach of the coast or of the arms of the sea and estuaries which abound from the Savannah on the south to the Penobscot on the north. The back country, forming the eastern or Atlantic slope of the Appalachian chain, was little more than a hunting and trapping ground or a field for primitive trade and barter with the Indians. As for the vast “hinterland,” west of the Alleghenies, it was, up to the middle of the eighteenth century, when the final struggle between England and France for supremacy on this continent began, an unbroken wilderness, inhabited only by hostile savages, and unknown to any white men except the Jesuit priests and the cunning traders of French Canada. For all these reasons, the gaze of the English-speaking colonists from the earliest settlements to the beginning of the conquest of Canada was always bent toward the sea, and all their enterprise and energy were directed to the commerce of the ocean. Under such conditions, the development of skill in ship-building was inevitable; and with that necessity was also bred a scientific alertness in marine architecture itself which, as soon as political independence freed its scope, became supreme throughout the civilized world. The outbreak of the Revolution of course, for the time being, put an end to merchant ship-building in all American ports. But in Philadelphia the paralysis was only temporary, and the energies heretofore directed toward construction of ships for the uses of peace were soon turned to the conversion of available merchantmen into vessels of war or privateers, and the building of new frigates ordered by Congress. The first American squadron, that of the ill-starred Commodore Esek Hopkins, was composed entirely of merchant vessels taken up in the harbor and converted into men-of-war in the shipyards of Philadelphia during the autumn of 1775. It was in the selection and conversion of these four merchantmen into cruisers that Paul Jones, founder of the American navy, first gave to the United States his energies and his talents. Thus Philadelphia was the birthplace of a new sea-power, and her shipyards have ever since been the foremost contributors to its growth, until even now, though only a century and a quarter old, it has achieved imperial rank. In November, 1775, Congress authorized the construction of six 32-gun frigates and seven other war vessels of less dimensions. Four of the frigates were allotted to Philadelphia shipyards. They were the “Washington,” the “Randolph,” the “Delaware,” and the “Effingham.” The first two were frigate-built from their keels, but the “Delaware” and “Effingham,” to save time, were built upon frames already on the stocks for merchant ships when the war began. On this account they were not quite as large as the regular frigates and rated twenty-eight instead of thirty-two guns.