The use of lights may be seen as a vessel enters New York Lower Bay. A steamship 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 lightship, 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 lightship a course lying nearly west takes the vessel to the outer entrance of Gedney Channel, marked by two buoy-lights. In passing 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 shore 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 canals 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. [Illustration: THE COMMERCE OF THE OHIO--TOWING COAL TO THE STEEL MILLS, PITTSBURG]