The following text may have been generated by Optical Character Recognition, with varying degrees of accuracy. Reader beware!

. more can be expected of the Mauretania under different~weather conditions. When Capt. Pritchard became commo- dore of the Cunard fleet some months ago he asked to be put in command of the Mauretania rather than of her sister ship, the Lusitania, for he contended that the Mauretania was the faster ship, that with her he would break all records. His judgment has-now proved itself cor- rect, for the Mauretania holds the east- bound record. ~~ THE PROGRESS OF RIVER IM- PROVEMENTS IN THE VI- _ CINITY OF PITTSBURG. ue BY J. W. ARRAS. (Continued from Feb. 11.) One thing stands inev tably in the way of the general use oi bDear-trap gates for navigation purpo-es. They cannot be introduced in long sections, such as for navigable passes or for shorter dams over their entire length, because of their rapid movement both upward and downward, which in the first instance would cauce a too sud- den reduction in the river's discharge, and in the latter case would create an immense wave, destruction alike to everything afloat both above and below it. As an automatic weir for pool regulation and rise control, how- ever, it has no equal, and its popu- larity for such use will undoubtedly continue unless a better device is dis- covered. It is probable that in future constructions, traps of varying widths will be introduced, thus afi ording greater flexibility to the system and more readily accommodating the op- erations to the varyng conditions of the water. CHANOINE WICKET WIERS. In the operation of the upper Ohio tiver dams the Chanoine wicket weir has up to the present time occupied but an unimportant place, perhaps much more so than it will in the future. It was the oriciral intention to have this weir act as the main regulating and rise controlling fea- ture. With the navigable pass up, the weir was to be of sufficient width and discharge capacity to permit the passage of the stream at a com- paratively high stage in order to pre- vent a material increase in the height of water above the dam. First the river was to be raised slowly as the needs of the pool might indicate, to be followed when entirely up by the raising of the automatic weirs or beartraps. . Several reasons may be assigned for failure to operate the THE MARINE REVIEW wicket weirs more generally. - First, the Davis island dam had been ee vided with such weirs on an extensive scale. These were not long and were expected to work easily from the sef- vice bridge above. On the contrary, however, their operation proved un- necessarily laborious. Even the short- est wickets, only 9 ft. 9 in. long, were hard to maneuver. Second, the service bridge was subject to attack by ice, drift, derelict erait, Ct, read- ily injuring and even destroying it. And third, it was found upon com- pletion of Herr island dam and dam No. 6, neither of which has a wicket weir, that they are much easier to operate than Davis island dam and could be maneuvered at higher stages of the water. Nevertheless, each succeeding structure has been sup- plied with ample wictet weir facili+ ties, with wickets in more than one instance longer and heavier than are the pass wickets of He-r island dam and dam No, 6, each of which are about 1 ft. longer than tiiose in the Haes at. Davis island dzm; in order to overcome the difficulty it was de- termined to operate the larger weir wickets by compressed a'r conducted through pipe lines constructed in dam foundations from power plants to abutments. Already o erating winch- es for the purpase have been provided and are installed ready for experi- mental use at dam 2, where the long- est weir wickets are placed, to be tested when conditions render such service, necessary. Should they fail tO Operate satisfactori'y after thor- ough trial. it will not result in their abandonment. It has long since been suggested that such wickets should He Made much shorter, s*y 6 to 8 ft. long, in order to induce their more frequent operation, the substructure underneath being a concrete fixed dam. This would naturally be the next step. However, first they will be thoroughly tried az: severat dams. But probably to the general public the lock is always the most interesting feature of a slackwater system be- cause it is the part with which they come in closest contact while passing along the stream. The Ohio river locks are among the targest in area in the world, being 110 ft. wide by 600 ft. long in their useful dimensions, and affording a safe navigable depth of 9 ft. over tteir lower gate sills, measured from normal surface of lower pools. Locks 1 and: 6 are built of stone masonry. Nos. 2 to a inclusive, were originally constructed of concrete with stone facing on river exposure of river walls, and tim- ber facing in lock chambers, -- As the timber decays, as it has in scme jp. stances, it is beng replaced with concrete. At some locks the heavy stone coping has also b-en replaceq with concrete. ' | RECENT CHANGES IN DESIGN. In this connection it is worthy of attention that in recent years river construction works have undergone important changes. Formerly all locks, piers, and abutments were built of stone, and fixed dams of timber cribwork filled with broken stone, except.an occasional stone masonry dam. Frequently also no great ef- fort was made to se:ure deep foun- dations, the structures as far ag possible being located on rock, even occaionally at considerable disadvant- age to navigation interests. In recent years, however, a'l government struc- tures are being built of concrete, where possible throughout, the con- crete in this vicinity ucually being ' composed of river gavel and sand and Portland cement. These struc- tures are now almost invariably mon- olithic, the lighter members being re- inforced with steel rods or beams. This method of construction is much less expensive than tne old, besides being stronger and it is thought more durable. Another decided advantage is that its construction can be accom- plished in much sho-ter time than stone masonry, and it is adaptable alike to foundaticn and superstructure purposes. Locaticns are determined with special reference to tne needs and advantages of navigation, and if on gravel an equally good foundation is obtained by building tne concrete structure on piles. Thus a_ stable structure in the main is secured; but steps must be taken to protect against scour by means of st-:n--filled cribs, piling, heavy riprap, etc. GATES OF ROLLING TYPE. The Chio river lock gates are all of the rolling type, withdrawing into recesses extending into the banks back of the Io k-. ~The gates ae drawn back and 'orth cn iracks, much like railroad car, by me ns of huge chains windirg on grooved steel drums. The locks, are filed and emptied of water in nearly every in- stance through large valves in the river walls. Sixteen so-called butter fly valves, each 41% ft. i: diemetem are located above the dams for fill- ing the locks to the level of the up- per pools, and 16 be- low the dams for emptying the locks to the the pools. These are overated directly from the power plants by oil pumps similar valves level of lower valves