the south of the peninsula on which the city was placed. At Sidon, similar but less extensive works long testified to the wealth and engineering genius of the Phœnicians. The breakwaters were principally constructed of loose rubble. Carthage, in another part of the Mediterranean, also possessed a harbor, though its site is not very satisfactorily determined. It was in two divisions, formed by moles; time, however, has dealt so hardly with it that few traces remain. In Greece nature provided so many navigable inlets that little remained to be done by man. Nevertheless, some minor works were executed at the Piræus and elsewhere, chiefly for warlike purposes. The Romans, finding ships necessary to the dominion of the world, set about constructing harbors for them. The coasts of Italy still show how well they understood both the principles and the practice of this branch of engineering. A distinguishing feature of their harbor-making is the open or arched mole. Built with open arches, resting upon stone piers, it gives full play to the tidal and littoral currents, thus preventing the deposit of sand or mud; but in proportion as this advantage is increased (by increasing the span of the arches), so also is the agitation, and consequent insecurity, of the water within.
The decay of commerce and civilization, consequent upon the fall of the Roman Empire, put a stop to harbor-making; nor did the art revive until the revival of commerce by the Italian republics of the Middle Ages. The rich traffic of Venice and Genoa soon led to the construction of suitable ports at those places; and the moles of the latter city, and the works in the lagoons of Venice, remain to this day. France was next in the field, embanking, protecting, and deepening the mouths of the rivers along her northwestern shores, as at Havre, Dieppe, Dunkirk, etc. In 1627, during the siege of La Rochelle, Metezeau constructed jetties of loose rubble-stone, to prevent access to the city. England lagged far behind her Continental rivals. With few exceptions, her ports were absolutely unprotected, or rather uncreated, until late in the last century. Two of the few exceptions were Hartlepool, where a harbor was formed about 1250, and Arbroath, in 1394. In the seventeenth century, at Whitby and Scarborough, also in Yorkshire, rough piers were thrown out, protecting the mouth of the port; while at Yarmouth, in Elizabeth's reign, a north jetty, and subsequently a south one, were formed. An ancient mole existed at Lyme Regis. But the chief efforts of the early English engineers were directed against the shoals and waves of Dover. With the advent of Smeaton, however, things took a different turn; and now few countries surpass Great Britain in the number of artificially improved commercial harbors, or in the just appreciation of their importance.
The development of harbor works in America, of course, belongs entirely to modern times. The first regular appropriation for harbor work in the United States was made in 1802; it amounted to $30,000, and was to he devoted to the erection of public piers at Philadelphia, Pa. In 1822 an appropriation of $22,700 was made for the construction of a harbor of refuge in Delaware Bay. The first approach to a river and harbor bill was made in 1826, when about $150,000 was appropriated for carrying on work in about twenty localities. From 1826 to 1838 aggregate appropriations carried by the various river and harbor bills were about $9,000,000. From 1838 to 1866 the aggregate expenditure was $6,600,000. The total aggregate expenditure of the United States on river and harbor works from 1820 to 1894 was $262,845,900. Since 1894 the annual amount set aside by Congress for such works has rapidly increased, until in 1900-01 the River and Harbor Bill called for an appropriation of nearly $60,000,000 for new work, and the Sundry Civil Service Bill called for an appropriation of $7,000,000 for continuing work in progress.
Harbor Construction. The designing and construction of harbors constitute one of the most difficult departments of civil engineering. In discussing this branch of the subject attention will be limited to commercial harbors, including harbors of refuge. The general plan of commercial harbors differs in different nations, and there is a great diversity of form due to the methods of commercial means of disposing of the freight received from vessels. It may be set down, as a general rule, that the ship itself does not determine the character of the harbor beyond the fact that it must be of sufficient depth to accommodate ships of the maximum draught using the harbor. In some of the most important ports of the world there are practically no installations for handling freight, the ships anchoring in the open harbor and discharging their cargoes into lighters. Railways play a far more important rôle in determining the arrangement of the harbor, particularly in regard to the dock and quay arrangement. In the last respect, also, the local movement of commerce of the city itself plays an important part.
Turning now to the natural conditions which influence the character and arrangements of harbors, it may be stated that the topographic and geologic conditions exercise a decisive influence. A harbor may be situated directly upon the seacoast or in some river, bay, or gulf, or far in the interior on some river or maritime canal. The effects of the ocean, the action of the winds and tides, and the general conformation of the shore-lines are other controlling factors in determining the arrangement of harbor works. Finally, the nature of the soil, whether alluvial, or diluvial, or rocky, plays an important part in the arrangement of the basins, either natural or artificial, and the adoption of quays, jetties, piers, etc.
The great variety of commercial and natural conditions which influence the arrangement of harbor works of course call for a corresponding variety of arrangements; it is obviously impossible to describe each here. For the sake of clearness we may somewhat arbitrarily divide harbors into, first, those located on a comparatively open coast; second, those located at river mouths or on bays or gulfs, and thus more or less landlocked; and third, those located well inland on rivers or maritime canals.
The simplest form of open-coast harbor consists of a quay wall or bulkhead wall open to the sea, and serving only to enable ships to tie up alongside the shore and discharge and receive cargoes. Such a quay affords comparatively no protection from the winds, tides, and currents. The next advance is a straight pier extending out from the shore. This pier affords little shelter to ships from waves coming directly inshore, but in case of winds and waves along shore it affords
