The Birmingham age-herald., 1903-09-13


 have been put mat a cost of more than $10,000 each. They are purely temporary, and will be removed upon the completion of the work. The most difficult task in the construction of a lock Is to get a suitable foundation and oftentimes the amount expended on the foundation is quite a large percentage of the entire cost of the completed lock-
 There are many who do not understand why locks and dams are built and why such vast sums of money should be spent on their construction. The dams are built simply for the purpose of keeping the water back so that it will be at least six feet deep at any point along the river, and the lock is an unique devise for all lowing boats to pass the dam. The low water mark of the Warrior river at the forks of the Locust and Mulberry is ex- actly 230 feet above mean low tide at Mo bile, or what is commonly called the sea level.
 Like Stairs.
 When the twenty dams across the War rior are finished, the water of the river will be not unlike gigantic stairsteps, each step being about ten feet high and in some cases as much as forty miles to the next step. The water in the river from one dam to another is called a pool. When the water in each pool rises to the top of the dam it runs over and so on all the way down the river
 At each of these dams there must be a lock through which boats can pass The lock is built at either end of the dam and consists primarily of two long parallel walls. the open ends formed by these be- ing equipped with immense iron gates. The enclosure thus formed is large enough to accommodate four 500-ton barges and a tow boat at the same time. The walls of the locks are now being built of concrete, which Is a mixture of sand and gravel and cement. The three locks at Tuscaloosa are built of cut stone. but 1t has been found that the concrete is not only more durable than the stone but that it is also cheaper.
 Because of the dam, the water of the river at one end of the lock is ten feet higher than at the other. When a boat from up the river comes along, the upper gates of the lock are opened the water in the lock being on level with that above the dam. The boat enters, the upper gates are closed and by means of culverts the water in the lock is gradually allowed to run out at the lower end by opening valves until 1t is level with the river be- low the dam. When it has reached that level the lower gate is opened and the boat steams out of the lock and on down the river ten feet lower than it was a few minutes before. The process of passing a boat through the locks re- quires between fifteen and twenty min utes.
 The fall of the river is greater at some points than at others. and the locks are therefore unequal distances apart. Locks 10. II and 12 at Tuscaloosa are very close together because of the rapid incline and the shoals at that point, while it is more than forty miles from Lock 10 to Lock g.
 Lock No. 8.
 Of the locks which are under construc- ton now, the government is doing the work on but one. At Lock 8 the United States employs all the laborers direct and pays them. At all the other locks the work Is let out by contract, and 1t is worth noting that all the contractors who have undertaken the locks which are al-