Part 4 (1/2)
Triple-expansion engines are almost universally used on modern steams.h.i.+ps, and a pound of coal now makes about three times as much steam available as in the engines formerly used. As a result a bushel of wheat is now carried from Fargo, N. Dak., to Liverpool for about twenty-one cents--less than one-half the freight tariff of 1876.
[Ill.u.s.tration: THE SCHOONER THOMAS A. LAWSON. THE FIRST SEVEN-MASTED SAILING-VESSEL]
The fastest liners consume from three hundred and fifty to more than four hundred tons of coal a day, and for each additional knot of speed the amount of coal burned must be greatly increased. Freighters like the Celtic consume scarcely more than half as much as those of the Kaiser Wilhelm II. type.
=Sailing-Craft.=--In spite of the growth and development of steam-navigation, a large amount of freight is still carried by sailing-craft; moreover, it is not unlikely that the relative proportion of ocean freight carried by sailing-vessels will increase rather than decrease, especially in the case of imperishable freight.
The square-rigged s.h.i.+p, or bark, has been very largely replaced by the fore-and-aft, or schooner-rigged vessel. A large full-rigged s.h.i.+p requires a crew of thirty to thirty-six men; a schooner-rigged vessel needs from sixteen to twenty. These vessels are commonly built with three and four masts; some of the largest have six or seven. They carry as many as five thousand tons of freight at a speed of about ten knots--only a trifle less than that of an ordinary tramp freighter. Some of the larger vessels are provided with auxiliary engines and propelling apparatus, which enables them to enter or to leave port without the a.s.sistance of a tug. Donkey-engines hoist and lower the sails, and perform the work of loading and unloading. They are admirable colliers and grain-carriers.
At the beginning of the twentieth century, about ninety thousand sailing-craft and thirty-five thousand steam-vessels were required to carry the world's commerce. Of this number, Great Britain and her colonies register nearly thirty-five thousand, and the United States over twenty thousand.
HARBOR SAFEGUARDS.--Excepting the open anchorages formed by angles in coast-lines, the greater number of harbors consist of small coves and river-mouths. In these, although there may be a considerable area of water, there is not apt to be much sailing room; it is therefore necessary to mark off the navigable channels.
For this purpose buoys of different shapes and colors are used by day; by night fixed and flas.h.i.+ng lights are employed.
The buoys of permanent channels are usually hollow metal cylinders or cones about two feet in diameter, anch.o.r.ed so that the end of the cylinder projects about three feet above the water. On entering a channel from the seaward, red buoys are on the starboard, or right hand; white buoys are kept on the port, or left side. Buoys at the end of a channel are usually surmounted each by some device or other fastened at the upper end of a perch. Thus, at the outer entrance of Gedney Channel in New York Harbor, a ball surmounts the perch; at the inner entrance the buoy carries a double square.
Sharp angles in a channel are similarly marked. In many instances the buoy carries, as a warning signal, a bell that rings as the buoy is rocked by the waves; in others, a whistle that sounds by the air which the rocking motion compresses within the cylinder; still others carry electric or gas lights.
The color of a buoy is an index of its character. Thus, one with black and red stripes indicates danger; one with black and white vertical stripes is a channel-marker. Temporary channels are frequently marked by pieces of spar floating upright. In some cases it is customary to set untrimmed tree-tops on the port, and trimmed sticks on the starboard.
Light-houses are built at all exposed points of navigated coast-waters, and beacons are set at all necessary points within a harbor for use at night. All lights are kept burning from sunset until sunrise. The color, the duration, and the intervals of flas.h.i.+ng indicate the position of the beacon. In revolving lights the beams, concentrated by powerful lenses, sweep the horizon as the lantern about the light revolves. Flas.h.i.+ng lights are produced when the light is obscured at given intervals. Fixed lights burn with a steady flame. In some instances a sector of colored gla.s.s is set so as to cover a given part of a channel. Range lights, set so that one shows directly above the other, are used as channel-markers.
[Ill.u.s.tration: CITY OF NEW YORK AND VICINITY, WITH HARBOR APPROACHES.]
The use of lights may be seen as a vessel enters New York Lower Bay. A steams.h.i.+p drawing not more than eighteen feet of water may enter through Swash Channel (_follow the course on the chart_). In this case the pilot makes for Scotland lights.h.i.+p, and merely keeps New Dorp and Elmtree beacons in range, giving Dry Romer a wide berth to starboard, until Chapel Hill and Conover beacons come into range on his port side. The vessel is then held on a course between Coney Island and Fort Tompkins lights until Robbins Reef light shows ahead.
For the liners that draw more than eighteen feet the task is more difficult, inasmuch as the channel is tortuous. At Sandy Hook lights.h.i.+p a course lying nearly west takes the vessel to the outer entrance of Gedney Channel, marked by two buoy-lights. In pa.s.sing between the lights the vessel enters the channel, which is also covered by the red sector of Hook beacon. The pilot continues between the buoy-lights until Waacaack and Point Comfort beacons are in range, and steers to this range until South Beacon and Sandy Hook light are in range astern. The helm is then turned, keeping these lights in range astern until Chapel Hill and Conover beacons are in range on the port bow. Turning northward nearly eight points, the pilot holds the bow of the vessel between Fort Tompkins and Coney Island lights, keeping sharply to his range astern, until Robbins Reef light comes into view through the narrows. From this point on, the sh.o.r.e lights are the pilot's chief guide.
So difficult are harbor entrances, that in most cases the underwriters will not insure a vessel unless the latter is taken from the outer harbor to the dock by a licensed pilot, and the latter must spend nearly half a lifetime as an apprentice before he receives a license. The charges for pilotage are usually regulated by the number of feet the vessel draws. The charges differ in various ports, but the devices for marking and lighting the channels are much the same in every part of the world. In the United States all navigable channels are under the control of the general Government.
=Inland Waters.=--Lakes, rivers, and ca.n.a.ls furnish a very important means of transportation. In Europe and Canada an enormous amount of slow freight is transported by their use; in China they are the most important means of internal traffic.
[Ill.u.s.tration: THE COMMERCE OF THE OHIO--TOWING COAL TO THE STEEL MILLS, PITTSBURG]
In the United States the Great Lakes with the Erie Ca.n.a.l and Hudson River form the most important internal water-way, and by them the continent is penetrated as far west as Duluth, a distance of more than one thousand three hundred miles. The traffic pa.s.sing out of Lake Superior alone is about one-third greater than that pa.s.sing out of the Mediterranean Sea at the Suez Ca.n.a.l. Much of this traffic goes across the continent, and the route in question is one of the great commercial highways of the world.
The Mississippi River and its branches afford not far from ten thousand miles of navigable waters. Ca.n.a.ls connect tributaries of this river with the Great Lakes at Chicago and at several points in Ohio. The development of the navigation of this great water-way was checked by the Civil War, and after the close of the war the great advance in railway building kept its improvement in the background. The general government, nevertheless, has done much to encourage the use of the Mississippi as a commercial highway, and many millions of dollars have been spent in widening and deepening its channel.[8] On the upper river grain and lumber form the chief traffic; on the lower part a large part of the world's cotton-crop starts on its journey to the various markets.
On account of the soft-coal fields and the steel manufacture in western Pennsylvania, the commerce of the Ohio River is very heavy, aggregating not far from fifteen million tons yearly. Much of this traffic extends to ports on the Mississippi.
The navigable parts of the Hudson and Delaware Rivers are estuaries of the sea or ”drowned valleys.” In each case navigation extends about to the limits of high tide. Both rivers carry a heavy freight commerce; the Hudson has a pa.s.senger traffic of several million fares each year.
Nearly every river of the Atlantic coast is navigable to the limit of high tide or a little beyond. Navigation extends to the point where the coast-plain joins the foot-hills. Above this limit, called the ”Fall Line,” the streams are swift and shallow; below it they are deep and sluggish. As a result, a chain of important river ports extends along the Fall Line from Maine to Florida.
River-navigation in Europe in the main is inseparably connected with the great ca.n.a.l systems. As a rule, the lower parts of the rivers are navigable for steamboats of light draught. Some of the smaller streams are made navigable by means of a long steel chain, which is laid along the bed of the stream; the boat engages the chain by means of heavy sprocket wheels driven by steam, and thus wind the boat up and down the river.
Ocean steamers penetrate the Amazon Valley to a distance of one thousand miles from its mouth; boats of light draught ascend the main stream and some of its tributaries a thousand miles farther. The Orinoco is navigable within one hundred miles of Bogota. Light-draught boats ascend the tributaries of La Plata River a distance of fifteen hundred miles.
The Asian rivers that are important highways of commerce are few in number. The Amur, Yangtze, Indus, and Cambodia have each considerable local commerce. The Hugli, a channel in the delta of the Ganges, has a channel deep enough for ocean steams.h.i.+ps. The tributaries of the Lena, Yenisei, and Ob have been of the greatest service in the commercial development of northern Asia from the fact that their valleys are both level and fertile.
Because of a high interior and abrupt slopes, the rivers of Africa are not suitable for navigation to any considerable extent; the channels are uncertain and the rivers are interrupted by rapids. The Nile has an occasional steamboat service as far as the ”First Cataract,” but in high water the service is sometimes extended farther. The Kongo has a long stretch of navigable water, but is interrupted by rapids below Stanley Pool. Similar conditions obtain in the Zambezi. The lower part of the Senegal affords good navigation. The Niger has in many respects greater commercial possibilities than other rivers of Africa. It is navigable to a distance of three hundred miles.