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and coal and iron products could not be moored ready for shipment to lower river ports. All this would tend to affect business generally, and above all the sanitary condition of the community would be appreciably deteriorated. structive influences are happily obviat- ed by the existence of a single perma- nent, reliable slack water construction. For almost 24 years this structure has served well the purposes for which it was intended. It required a few years to accomplish satisfac- tory results. The original structure was eyperimental in many respects, notwithstanding the Chanoine type of dam had been tested for several years on small streams in France. Little by little its adaptability to the larger conditions of a great river, with its sudden rises and freshets, drifts, ice, etc., has been applied, until in recent years it has met the needs of the com- munity quite efficiently. . These re- sults have not come by chance, but have required much thought, anxiety and labor on the part of those in charge and considerable expenditures' It is also a sig- by the government. nificant fact that while the service has been improving the physical con- dition of the entire structure has ma- terially depreciated. Much of this depreciation has been in large meas- ure dtie to the experimental nature of the structure, its working plant and operation. One thing after another was tried, often only to prove a fail- ure. Many experiments were costly, frequently ending in a complete loss. Nevertheless the service was gener- ally maintained and in the main. im- proved, until now it has reached a state eminently satisfactory. As in- stances in changes of operating meth- ods, formerly, and indeed for many years, it was became imminent and shghtly in ad- vance of its approach. This frequent- Jy occasioned through miscalculation of the progress or extent of rise a premature or even unnecessary lower- ing, causing the harbor level to de- cline as much as 2 or 3 ft. below its normal elevation several hours in ad- vance of the proper time for pool disposal, and before sufficient water had reached the harbor to maintain its normal condition. This policy was often detrimental to navigation, at least causing great inconvenience, and occasionally slight losses. All this has been changed. Now the dams are left standing as long as possible against advancing rises, until they are literally forced down by their on- Such de-' thought necessary to lower the wickets:as soon as a-rise: _ after all "THE MaRINE. REVIEW ward movement. Consequently the heads of the pools are generally so precisely regulated as to render the transformation from pool to open river unobservable. Again the orig- inal method of maneuvering Davis isl- and dam alone precluded consider- ation of every interest save itself,' and toa certain extent, Of course, navigation. Now, as must appear evident, there being a series of seven such dams in consecutive order, each must be operated mindful of the in- terests of the rest. Nothing short of such a policy would ever serve to accomplish their successful lowering without injury to some and probably a complete blockading of navigation. These two noteworthy might be multiplied many times in the history of the Davis island struc- ture <alone. Doubtless many have conceived the idea that the movable dams having been designed to meet the condition; obtaining on our local rivers, all. that- is necessary is to build them and set. the wheels in. motion and the struc- tures will automatically | do the rést. Nothing could be farther from the truth. The Ohio river, even at its source, is a large streem, which to control at< any stage and by any means is no mean undertaking. ers of such magnitude and velocity do not stop in their gulf-ward flow without offering resistance. Every inch, of closure to obstruct their course must literally be fought out until the entire passageway has been shut off and the water above the dam lies conquered in a placid pool. So also when released 1t again as- serts. its power with ever increasing force until its pent up energy has been expended and a normal condition attained: No matter as to the char- acter of machinery such, operations the personal element remains all-important and indispensable. The maneuvering of the dams must be performed by the operating forces to meet the varying conditions, and as: they change the methods of doing the work must change. No fixed rule can be laid down for the performance of the greater part of this work. It must be done as circumstances demand. For some time the navigation inter- ests and:the community in general have awaited the completion of the upper Ohio river structures. Doubt- less they might have been finished much sooner had the means for their con- struction been more promptly pro- vided, and especially had the first definite project been carried out, When examples: Riv- introduced 'for. 37' the earlier dams were constructed -- and provision made for those imme- diately following they contemplated -- only a 6-ft. navigation. Not until No. 6 was completed and dams 2 and © 5, inclusive, were well under way did -- it suddenly occur to those whose inter- ests were most directly involved that the pools should afford. ample depth to accommodate the deepest draught vessels in general use in this locality. Immediate steps were taken to ac- complish this end. Necessarily this meant increased delay in securing congressional authorization, addition- al funds to meet the cost of altera- tions and time for performing the work. Parts of the work already in place were removed, reshipped to factory, changed and replaced; ex-. tensive modifications at the works were made, often at great disadvant- ages owing to the absence of coffer- dams; and unbuilt portions of struc- tures' were redesigned and construct- ed to effect a 9-ft. navigation. No doubt had all this been foreseen and. covered in the original project not only much time, labor and cost could have been saved, but-the structures ©. themselves in many respects would' -- have been better and generally more satisfactory. However, the change proved most worthy, and notwith- standing its responsibility for some undesirable features causing extra care, labor and expense in mainte- nance and operation, navigation has gained a material advantage right at the outstart of the vast canalization project of the Ohio river, which will unquestionably be carried out through its entire length. Nor is this 9-ft. depth merely a theoretical one not available for the uses of navigation. Any craft drawing not exceeding 9 ft, aay. now navigate safely from Pittsburg to dam 6, without danger © of grounding if the. channel is closely followed. (To be continued.) a MASTERS AND PILOTS ELECT OFFICERS. The National Association of ee ters, Mates and Pilots of Steam Ves- sels, at its annual convention in Wash- ington, Jan. 23, elected officers for the ensuing year as follows: Presi- dent, John H. Pruitt, of Brooklyn; first vice president, A. L. Pease, Port- land, Ore.; second vice president, A. R. Mackey, Pittsburg, Pa.; third vice president, William Sommers, Camden, N. J.; counsel, L. B. Dow, New York city; secretary, C. L. Warwick, Balti- -- more; treasurer, A. B, Dowlin, Jersey City; BT.