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1901,] MARINE REVIEW. | 27 difference of opinion. That there should be errors in observations and deductions connected with such a complicated subject, is no cause for surprise, and does'not, in my judgment, in any way detract from the credit due him. i In what I have written I have tried .to include all that has been carried out practically in engine balancing, which can be regarded as any approach toward the solution of the problem. Of the theory I have given enough to exhibit the exact nature of the problem, and have shown that the indications of theory are fully borne out by the consequent phenomena of ship vibrations. I have shown that the old counterbalancing took much too narrow a view. It was adopted long before the exact nature of the forces had been fully investigated, and it can only be looked on as a first approximation to a solution. The discussion has also, I believe, made it clear that the Y. S. T. system is only a partial solution of the balancing problem, and that while it may annul the unbalanced horizontal forces, the effects of which never gave rise to very special remark, it gives an engine in which some of the forces left unbalanced exert very nearly their highest possible effect. With this view of the system, it would have ben out of place in an already very long paper to give the numerous methods, alge- braic and semi-graphical, which have been proposed to determine crank angles and moving masses. The engine is costly, heavy, and on account of the calculations required, troublesome to design. When completed it is only a partial solution of the problem, and for the conditions of the fast vessels and high-speed engines of today the solution is far from sufficient. I have shown fully how five and six-crank engines must be adjusted to produce a balance up to the fourth period. That this engine, occupying much valuable space, complex. and costly, should have been introduced, even in a few cases, shows how pressing is the necessity for a more. complete solution of the balancing problem, As I stated in the beginning, it is my belief that the MacAlpine system is the best solution of the problem of engine balancing to prevent hull vibration that has thus far appeared. For this reason I have placed in strong contrast. the features of this and the Y. S. T. system, inasmuch as the latter has been applied in more cases than any other system which «claimed to give 'a reasonably complete solution of the problem. The discussion has aimed to show that the MacAlpine system considers fully -the dynamical problem, and gives a complete solution; that it makes no unwarrantable, even if approximate, assumptions. It has been shown that the lack of complete torsional balance leads to very slight response from the ship, and that this single omission to secure absolutely perfect balance is fully justified, as the advantages gained through the admission of this slight lack of balance very much more than offset the disadvantages. It:is to be particularly remarked that the engine which thus realizes the perfect solution of the balancing problem is a perfectly practicable one. It is of a type in common use, and with the performances of which we are perfectly familiar, to which are now added, however, the necessary condition for the solution of this great problem. It has the additional advantages of great compactness, simplicity, and accessibility. If the discussion which has been given should, as I hope, prove conclusive, I trust that the gentleman who has encouraged the preparation of this paper, and who, if I am correctly informed as to his identity, is fully able to test the MacAlpine system, will do so. After a most careful study I am convinced that the . system is correct, and I believe the results will amply compensate him for having given it an opportunity for demonstration. NEW YORK'S GREAT CHANNEL TO THE SEA. -- Some figures recently published regarding the work of providing a channel of 40. ft. depth from New York to the sea, show the wonderful progress that has been made of late in constructing high-powered suction dredges. The dredges Thomas and Mills, built at Sparrows' Point, Md., some time ago, and constructed especially for the New York channel contract, have already succeeded in excavating a mile of the channel to a depth of 42 ft. and a width of 2,000 ft. The depth of water over this mile of new channel before dredging began was 14 to 18 ft. The dredges work night and day and in every hour and twenty minutes each of them, work- ing over a reach of 1,000 ft: width, sucks up 4,700 tons of sand. Capt. A. B. Connor, the superintendent in charge, commends in the highest terms the use of Pintsch gas buoys in prosecuting work of this kind by night. He says it would be almost impossible to carry on the work by night without the gas buoys. Six of them are used, three on each side of the channel, and their greatest advantage is their reliability. They are of the kind that can be charged to burn for a very long period--several months-- and can always be depended upon. The electric lights on Gedney's chan- nel have, on the contrary, Capt. Connor says, gone out several times while the dredging job has been under way. ' TRADE NOTES. "Elisha Webb & Son, Philadelphia, have recently completed the equip- ment of the tugs Vigilant and Anna W., built at Neafie & Levy's yard, Philadelphia, and the Patience, built at John H. Dialogue & Son's yard, Camden, N. J. They are now fitting out the steamer Springfield, building for the Bordentown & Philadelphia Transportation Co. at Pusey '& Jones' yard, Wilmington, Del. They are also in receipt of the order for cooking apparatus for two large freighters building at the Maryland Steel Co.'s works, Sparrow's Point, Md. In the Chicago store of the Boston Woven Hose & Rubber Co., 185- 187 La Salle street, a room has been fitted up for the express use of cus- tomers and friends who may happen to be in the city. The room contains the daily papers, magazines, writing materials, etc., and the services of a stenographer if required. Se Excursion rates to Florida via Baltimore & Ohio R. R. and Wash- ington, D. C., passing through the beautiful cities of the south. Stop over privilege allowed on all round trip tickets. Two fast trains leave Cleve- land daily at 3:00 and 11:20 p. m. Call at city ticket office, 241 Superior street. tf BELLEVILLE GENERATORS Grand Prix 1889 Originated 1849 Hors Comcours 1900 Latest Improvements 1896 Number of Nautical Miles made each year by Steamships of the Messageries Maritimes Co., Provided with Belleville Generators--Since their Adoption in the Service. Year. Australien | Polynésien ra cow ias mir : Chili Cordillére Laos | Indus Tonkin Annam Atlantique ee 67,728 2,460 | 188 lcc cn | 68,247 | 68,331 204 (CO ali 68,247 | 68,403] 69,822| 23,259 1696 ec 68,379 | 68,343| 68,286] 68,247 1994.62.54... 68,439 | 68,367] 68,574| 68,439] 37,70! 1696... fs... 68,673 | 68,766| 68,739| 68,808| 40,887| 28,713 1696. 69,534 | 92,718] 69,696] 69,549| 62,205]. 63,153] 40,716 1807.56.05, 68,250 | 69,606] 92,736 | 69,555] 62,235] 76,110 | 63,357] 43,146 1898.. 70,938 | 69,534 | 69,552 | 69,597| 62,526] 63,240] 63,240] 62,553] 63,954| 22,707 1590... 69,534 | 69,615 | 67,431 | 90,405] 60,246] 62,778| 62,868| 52,344| 54,855| 44,007| 22,884 6. 69,534 | 67,494 | 69,744] 69,564 | 61,719] 62,382] 62,502] 51,471] 53,373] 62,016| 63,066] 52,140 Total)... 757,503 | 713,637 | 644,784 | 597,423 | 387,519 | 356,376 | 292,683 | 209,514 | 172,182| 128,730] 985,950 | 52,140 ATELIERS ET CHANTIERS DE L'ERMITAGE, A ST. DENIS (SEINE), FRANCE. _, , WORKS AND YARDS OF L'ERMITAGE AT ST. DENIS (SEINE), FRANCE. | "TELEGRAPHIC ADDRESS: BELLEVILLE, SAINT-DENIS-SUR-SEINE. Ree