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50 no load the turbo-generator commonly takes about one-eighth the total quantity of steam that it requires at maximum output, and the pressure below the stop valve is then not far removed from that of the atmosphere. At 2400 kilowatis the turbine proposed above will, it is asstim- ed, take 4U,800 Ib. of steam per hour, and the pressure below the stop-valve is 175 Ib. absolute, or, say, 160 lb. gage pressure. Plotting down a diagram such as that an- Lbs per sq.in. Zs per Hour 200 Le E 50.000 /60 a 40.000 gon 120 b 50000 4 : oF e Yt Ss Ras qo 5 0 p 60 ~~ 4 hg E120 000 " g or ye? X al er Ss pasue les 4 40 | 404 ae 0.000 e ; / Qs : ; Sek bs perihour- e720 409 "800 _/200° 1600 2000+ 2400 6 Coad 77K, PW. nexed, the consumption at 2400 kilowatts being 40,800 lb. per hour, it will be about 5100 Ib. per hour at no load (magnets excited). Joining these two points by a straight line, the consumption is obtained at intermediate loads. Similarly, the gage pressure below the governor-vyalve being 160 Ib. per sq. in. at 2400 kilo- watts, it may be taken as atmospheric al no load (magnets excited). Joining these by a straight line as indicated, the gage pressure at all other loads can be read off with considerable accuracy, the output, in fact, being usually very nearly in direct proportion to the gage presstre. If the same turbine were run at 1200 in place of 1500 R. P. M,; its output and efficiency would diminish nearly in direct proportion to the reduction in speed. In place of 2400 kilowatts it would gener- 2400 X 1200 ate about----__-- = 1920 kilowatts, and the total steam consumption would be little changed. In fact, steam reac- tion turbines are generally run at ratios of blade speed to steam speed at: which the efficiency curve is fairly well repre- sented by a straight line passing through the origin. At some futtire date we may compare the proportions obtained by these empiri- cal rules with those demanded by a more complete theory of the action of the tur- bine, and with the results actually ob- tained in practice with a large turbine of which. complete trial data are available. In the meantime the rules in question, in spite. of their empirical character, may be taken-as giving a very fairly proportion- ed turbine. THe Marine REVIEW FASTEST WAR VESSEL IN THE oe WORLD. There is at present undergoing her speed. trials a torpedo-boat destroyer built for the British navy which can rightly claim to be, and will be for some time to come, the fastest war vessel in the world. She has been accurately named the Swift and has been built not only as a kind of ex- perimental vessel, but under great secrecy at the Birkenhead ship build- ing yard of Messrs. Cammell Laird & Co., on the river Mersey, Liver- pool. Her displacement is about 1,800 tons and the horsepower of her tur- bine 'propelling machinery is nearly 30,000. That these are startling fig- ures for a torpedo-boat destroyer will be evident to anybody who knows anything about this kind of war ves- sel, or cares to look up records of them. She belongs to no class nor are there any other ships building exactly on her designs. She is, as be- fore stated, an experimental vessel for the British navy and her contract speed was stipulated at 36 knots. As a torpedo-boat destroyer she is the largest yet built, her principal dimen- sions being, length, between perpen- diculars, 345 ft.; breadth, 34 ft.; depth, 20 ft. 4 in; with a displacement at mean load draught of about 1,800 tons. Her armament consists of four 4-in. breach-loading guns, two on the forecastle and two on the upper deck, and two 18-in. torpedo tubes on the upper deck. She is fitted with. quad- ruple turbine machinery.of the Par- sons. type, which drive four shafts, there being one propeller on each shaft. The turbines are placed in two distinct engine rooms in order to min- imize the capacity of any one: water- tight compartment, and several noy- elties have been introduced in order to accommodate machinery of the large power required in the compara- tively small space at disposal. There is an installation of 12 boilers of the express straight tube. type, these be- ing arranged for the burning of oil fuel exclusively. Her designed speed is) 36 knots, but whether the vessel will. maintain. this under. severe ad- miralty conditions remains to be seen. It is a happy augury, however, that on some of her trials so far she has credited: herself with 38 knots. AWARDS FOR DESTROYERS. Secretary of the Navy Metcalf on Sept. 19 awarded contracts for the construction of the 10 torpedo boat destroyers authorized at the last Ses- sion of congress, and for which bids were opened recently. Each of the o® following companies is to build two _ of the destroyers: Fore River Ship Building Co. Quincy, Mass; New York Ship Building Co., Camden, N. J.; Newport News Ship Building g Dry Dock Co., Newport News, Va.; Bath Iron Works, 'Bath, Me. ang William Cramp & Sons Ship & En- gine Building Co., Philadelphia, Pa, The contracts with the Fore River and Cramp plants are for the con- struction of vessels on their 6wn plans for hull and machinery, the re- mainder of the vessels to be con- structed on the plans made by the navy department. a TRIALS OF SCOUT CRUISERS. The three scout cruisers, Chester, Salem and Birmingham, the only ships of their (class. in: the world, are to leave the Charlestown navy yard within a few days for the exhaustive set of competitive tests which will be watched everywhere with interest. The final official acceptance trials will: be: .: Oct: 6, the » Birmingham; Oct &, the Salem, and'-Oct. 11 the Chester. Then' will come the stand- ardization tests over the official measured mile course, off Rockland, Me., 'the Birmingham, Oct, 16;- the Chester, Oct. 18, and the Salem, Oct. 25; after which the three cruisers are ordered to assemble on Nov. 15 at Hampton Roads, whence they will start on a 2,000 to. 3,000-mile, coal- endurance test and competitive run to: Guantanamo. This' last test will be* for the purpose of establishing the merits of the different kinds of motive power used respectively in the three cruisers, under equal condi- tions, both as to the amount of coal consumed, sailing and uniform man- euvers. Jt. is reported that the Oceanic Steamship Co., of San Francisco, has arranged to sell to the Pacific Mail Steamship Co., the steamers Ventura, Sierra and Sonoma. These steamers are controlled by the Spreckels in- terests and were taken off the San Francisco - Honolulu - Australia run several months ago and have since lain idle. The Pacific Mail Steamship Co. is controlled by the Harriman lines and it is said to be the inten- tion to institute an express service to Ancon, on the Pacific side of the Isthmus of Panama, thus enabling coast bidders to compete in the mat- ter of supplies for the Panama canal. John D. Spreckels has announced that there is nothing in the report, but was unwilling to discuss the matter defi- nitely.