Inland Waters as Sources of Food.—Most of the stories of fisher men are based on the experiences of amateurs in inland waters. In apiteof all the stories, however, the amount of food procured in this way is small. This is largely because in most inland waters the supply of fish is too small to tempt professional fishermen. The fish are caught by amateurs who go fishing only a few times each year. Nevertheless some rivers like the Illinois and some of the larger lakes support far more fishermen in proportion to their size than do the seas. These men and those who catch salmon and other fish at the mouths of rivers entering the sea procure two-fifths of the whole catch in the United States. In Russia, also, the Volga, Don, and other rivers support very extensive fisheries, the most famous of which are the sturgeon fisheries, where caviar, or sturgeon roe, is procured.
Inland Waters as Barriers.—The importance of inland waters as barriers is even greater than that of the oceans. Every person who reads this book has probably been put to inconvenience hundreds of times because of some comparatively slight water barrier. Per haps it was only a brook across which it was necessary to jump. Or perhaps it was a river which made it necessary to go several blocks out of the direct route to reach a bridge or ferry. The reason why inland waters are more troublesome than the vast water barrier of the ocean is, their small size and great number. Because they are small, one can rarely travel far on them in the right direction. Be cause they are nuinerous, frequent bridges are necessary along most routes, or else one must keep changing from land transportation to water transportation.
The Mississippi River as a Great Water Barrier.—The Mississippi river illustrates many of the ways in which inland waters serve as barriers. On the map notice how largely this great river forms the boundary between States. This is natural, for the stream is so wide, so deep, and so subject to great floods that it is very difficult to cross it in boats or to bridge it. Until Memphis is reached,. 500 miles up stream there is no bridge, and of the two there only one is passable for wagons. The next bridge is near Cape Girardeau, 175 miles farther up, and the next at St. Louis,125 miles still farther. Not till St. Louis is reached, over 800 miles from the Gulf of Mexico, or 1270 as meas ured along the windings of the river, is there a second bridge which can be crossed by wagons and foot passengers as well as by trains.
In order to realize the importance of the Mississippi barrier, consider how many delays it causes. Even where a ferry is close at hand, it is a slow way of travel. At New Orleans, for instance, all railroads connecting with the west have to run their trains on to ferryboats. This takes time, for the cars have to be shunted back and forth, the ferryboat moves slowly, and the landing stage must be raised or lowered so that the tracks on the land and on the boat meet exactly. Moreover, the loss of life on the river, the extra effort involved in crossing it, and the long delays all cause expense, and so does the building of boats, bridges, and tunnels, so that every water barrier is a great consumer of money.
To sum it all up, the chief reason why the Mississippi and other bodies of water are barriers is that they require a change in the mode of traveling. The train must run on an expensive bridge or ferryboat instead of an ordinary track; the pedestrian must swim or get a canoe or other boat. The change is what makes the trouble, for when a man or a piece of freight is once aboard the boat it is a cheap and easy means of conveyance. The man who keeps a motor boat on the banks of the Mississippi has the means of overcoming the water barrier almost as effectively as his automobile overcomes distance on the land.
How Water Barriers Determine the Location of Cities : London.— Since bodies of water act as barriers, the places where it is easy to cross them are likely to develop into towns. This is because roads converge at such places, and people are often obliged to stop ti ere. London is a good example. Ten or more centuries ago the most im portant part of England was the southeastern corner. The next most important part was the region north of the lower Thames, and south of the curious square-cornered indentation called "The Wash." The silk merchant who went from Cambridge to Paris, for example, or the pilgrim who was returning from Rome to Norfolk, was obliged to cross the Thames, or else go around its head. The lower reaches of the river were not easy to cross because the stream widens toward the sea and is bordered by marshes. Hence traffic converged at the lowest point where the stream is narrow and the banks are firm, and there London grew up. Its site was where the water barrier could be easily crossed. That is why London Bridge, at the point where the river was first easily crossed, is one of the world's most famous struc tures.