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COMMENT ON AMERICAN SCOUT CRUISERS. The London interesting article on the three new of the United States navy, the Birmingham, the Salem and Times prints, a very scout cruisers the Chester, the former being fitted with reciprocating engines, the second with Parsons turbines, and the last with turbines of the Curtis pattern. In other respects than the machinery the three vessels are nearly identical. In its comparison the Times says: "On the four hours' full speed trial the Birmingham attained a mean speed of 24,325 knots, with 191.66 revolutions per minute, and 15,540 indicated horse- power. The Salem attained a mean speed of 25.947 knots, with 378.39 revolutions: ©*"per' ) minute, and:< @ "shaft" horsepower -- ascertained by using a torsion meter--of 19,200 horse- power. Allowing 10 per cent for en- gine friction the corresponding indi- cated horsepower of reciprocating en- gines which would have been required to drive the Salem at this speed would have been 21,100 horsepower, and the consumption of coal per indicated horsepower per hour would have been 1.81 pounds, as against a consumption of 1.92 pounds for the Birmingham. The turbines, therefore, gave an in- crease of 1.62 knots in speed, and an increase in (equivalent) indicated horsepower of nearly 5,600 horsepow- er--or about 36 per cent--with a small economy in coal consumption. "Another contract trial of greater practical importance than the _ speed trial of the American scouts was that for 24 hours at a speed of about 22.5 knots. The Birmingham aver- aged 22 2/3 knots with 172 revolutions per minute developing 10,760 I. H. P. and burning 1.91 pounds of coal per I. H. P. per hour; she ran 2.47 knots per ton of coal burned at this speed. The Salem averaged 22.536 knots with 312.5 Tevolutions per minute, the -- shaft whorsepower was 9,340 horsepower (corresponding to about: 10,275 I. H. P.), the coal burned was 1.78 pounds per I. H. P. per hour, and the ship ran 2.73 knots per ton of coal burned. In the case of the Chester. the shaft horse- POwWer was not measured, but she av- eraged 22.78 knots for 24 hours, with 473.5 revolutions per minute, and ran 2.82 knots per ton of coal burned. This trial represents continuous steaming at sea in favorable weather; starting with bunkers full (1,250 tons), the dis- tance which could be covered before coal was exhausted would be about 3,500 knots. This is a good coal en- durance for vessels of the dimensions, full. 'and best sea-keeping "TAE Marine Review and is British scouts. "Another 24 hours' trial was made at 12 knots, the cruising speed for the class. The Birmingham averaged 12.23 knots, developing 1,600 I. H. P., with 91.4 revolutions per minute, burning 2.89 pounds of coal per I. H. P. per hour and running nearly six knots per ton of coal burned. The Salem aver- aged 11.93 knots, with 164.1. revolu- tions per minute, burning 2.68 pounds of coal per estimated I. H. P., and run- ning 6.6 knots per ton of coal burned. The Chester averaged 12.2 knots with 250 revolutions per minute, and ran 6.68 knots per ton of coal burned; she is fitted with cruising turbines. It is interesting to note that- both the turbine-propelled vessels surpassed the Birmingham in economy of coal con- sumption, even at this low cruising speed when only 8 to 10 per cent of the maximum engine power was de- veloped. "In the design of these vessels and their propellers full use has been made of modern experimental methods. Models were tested in the experi- mental tank at. Washington to deter- mine the "tow-rope" resistance and "effective horsepower' corresponding to various speeds. Every man was taken to secure efficient propellers. For the Salem four competitive de- signs for propellers are said to have been obtained, including one from this country and another from Germany. Photographs taken of the wave phe- nomena surrounding the vessels when running their full. speed trials furnish evidence that the form and dimensions adopted were admirably well-suited for the high estimated speeds. "As matters stand the United States navy possesses for the moment the two swiftest, most powerfully armed, scout cruisers afloat in the Chester and Salem; and the builders--the Bath Iron, Works and the Fore River company--deserve hearty congratulations on their unqual- ified success." H. M. S. INDOMITABLE. The magnificent run which H. M. S. Indomitable has just made as shown that the new battleship cruiser is capable of speeds hitherto unattainable in any navy, with the exception of such craft as torpedo boat destroyers. It is impossible to give precise particulars of a perform- ance concerning which no official informa- tion has been supplied. Broadly stated, her passage from Quebec to this country was made in five and a half days, but the number of hours has not been made pub- lic nor the rate at which she came down ' far superior to that of the. very fine performance. OR the St. Lawrence. All that' can be said is that leaving Quebec early on Wednes-' day morning, the 29th ult., the Indomitable for the 719 miles down the St. Lawrence river had to steam at a vomparatively low speed. At Belle Isle, on the New- foundland coast, the race home com- menced, and the run across the Atlantic was covered at an average speed variously stated as 25.13 and 24.8 knots. For four hours a speed of 26.4 knots was attained. The great speed at which the cruiser has steamed across the ocean is made all the more remarkable by the fact that this ves- sel has not been stripped in order to allow her to make a record run. She carried the heavy guns of a Dreadnought, a thick coat of armor, her magazines full of ammunition, and all the rest of the equip- ~ ment of a man-of-war ready for active service. Her cost was enormous, ap- proaching close upon £2,000,000, and 'be fore the year is out, another two of these vessels will have been added to the strength of the navy. The Indomitable is -- 560 ft. long on the water-line, 7814 ft. beam, and has a displacement of 17,250 tons. Her propelling machinery consists of Parsons' turbines, capable of develop- ing 41,000-horsepower. She is one of a new group of cruisers, mainly intended for the convoying of fast merchant steam- ers should war break out. It is stated that on. the measured mile she attained a speed of 28 knots. But the official re- ticence concerning her performance is complete. Steam is supplied by Babcock boilers, made in Glasgow. Probably the most interesting question which she has settled is her steaming range at full power. This may be taken at, in round numbers, 2,500 knots. Her bunkers hold 3,000 tons of coal; how much more she carried, or whether she carried any addi- 'tion at all, has not been stated. She is, we believe, fitted to burn oil fuel. We understand that she reached Cowes at 9:40 p.m. on Monday with empty bunkers. Now, it is not likely, that her machinery used less than 15 Ib. of steam per horse per hour. Even that figure stands for a If her boilers evaporated 10 lb. of water per pound of coal, we have 1% lb. of coal per horse per hour, or, say, 60,000 lb. or 27 tons per hour. If her actual steaming time was 132 hours, then she must have burned 3,564 tons on the trip. Two or three hours more or less will not make much difference. Some allowance may perhaps be made for the run down the St. Law- rence. If she had only 3,000 tons of coal to burn then she must have been helped by oil fuel, or her turbines did not exert 40,000 horsepower. In the latter case the efficiency of the ship as a whole is re- markable. Her propellers must be admir- able, and the form of the hull under water reflects the greatest credit on her designer. No doubt, in process of time,