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ES -- eS ee ee ) ) Cee ee MARINE \ REVIEW. Vou. VIEL. Torpedo Boats for the U. S. S. Maine and Texas. SOME DETAIL ABOUT THE LITTLE VESSELS THAT REPRESENT A DEPARTURE IN OUR NAVY--A DESCRIPTION SPEC- IALLY PREPARED FOR THE REVIEW. _ These little vessels are something of a departure in our navy, although they have been in use in other navies for some time. Hitherto our service has devoted its attention to larger torpedo boats like the Cushing and the Ericsson, which is building at the Iowa Iron Works, Dubuque, Iowa. The functions of the two classes of boats are different, the larger or first class boats being expected to be capable of keeping the sea for some time, while the small ones, third class, are not intended for extended ser- vice but simply operate from the ship which carriesthem. How- ever, they have a high rate of speed and in an action where the vessels to which they belong cannot make as much speed as they can, they could do a great deal of damage. The boats for the Maine and the Texas ave of the same general type but differ in size, as will be seen by the following table of dimensions. MAINE. TEXAS. Voengthonss. Wi Li cievtscccccorss.: tree 58 ft. 6 in. AS tt. Ty in. Renguieever alleen. scsecteestnensss sores 61 ft. 8 in. 50 ft. Beamsat water line...2...-.ssccss-0ecece 9 ft. 3-16 in. 9 ft. 3-16in. Mies: drat ote sects ecrccewencnnees vesiee ese 2 ft.92 in. 2 ft. 13 in. Displacement, tons:...:-......-..c00.-00s 14.8 12 16 Coefficient of fineness................000. 455 462 Weight of bull and fi'tings, pounds 13,785 10,992 Weight of equipment, pounds........ 219 184 Weight of ordnance and armor...... 3,435 3,460 The frames are 1 inch by 1 inch by .8 pounds and the ee verse frames 7% inch by 7% inch by .7 pounds. They will carry a 1-pounder rapid firing gun, and the Maine's boats will have a bow torpedo tube tor an 18-inch Whitehead, while those of the Texas will have a deck training tube for a Whitehead of the same size. The machinery presents a few novel features, although it is chiefly notable for excellence of design to secure lightness and perfect balance of the moving parts. It might be thought at first sight that nothing could be easier than to balance the mov- ing parts by simply making them of equal weight and moving in opposite directions, as has been done in this case, but there is another point which must not be lost sight of, that is the effect of inertia on the power actually given out by the cylinders. As most of our readers doubtless know, it is by no means the case if the indicator card shows a mean effective pressure at the be- ginning of the stroke, of some 50 pounds say in the high pres- sure cylinder, that this pressure is transmitted to the crank pin. The inertia of the moving parts must be deducted, and ina small cylinder where the piston speed is high, the reduction is very large. Of course, the effect of the inertia, if properly con- sidered, is beneficial as tending to make the pressure more uni- form throughout the stroke, but we have to be very careful that the reduction for inertia does not exceed the mean effective pressure, otherwise we should have the cylinder running tor part of the stroke doing no work and actually a drag on the other cylinders. This, however, has been carefully considered in these torpedo boats, and there is no doubt that they will work with unusual steadiness and smoothness at the remarkably high speed for which they have been designed. It may be explained that the balance has been secured by putting the cranks of the high pressure and first intermediate pressure opposite and like- wise those of the second intermediate and the low pressure, CEEVELAND,-O}. Ano CHICAGO IEE. AWG. 33551803: No. while the latter two are at right angles to the first two. As the high pressure piston is necessarily smaller than that of the inter- mediate pressure and likewise the second intermediate pressure than the low pressure, the balance of weight has been secured by making the smaller piston of each pair thicker than absolute- ly necessary for strength. As usual in all modern naval vessels, the piston rods, connecting rods, etc., areof the same size, so that all fittings and spare parts may be interchangeable. The following table shows the principal dimensions of the machinery: MAINE TEXAS, Type of ENZINE....... seeereeercesecseeeessentereennes TE eeher'g Quadruple expansion. ( EL Ps eerie te 6.00 5.25 Diameters of Cylinders | Ist I. Po..c-. sce. sereeeee 8 37 7.35 LDPRICHES...<<cseesbeyore | DOT. Pbsstteaact seteaks os dG 10.00 Ti Pisnd i dcsacescnseraces 15.75 14.00 Strokel in. in@h es Brig: ....scsssocee erases meee ee ce eee eee 8.00 8.00 Condensing surface, square feet ..............+8. svlegeios 150 116 Revolutions) pel, mimUtesrcsrencavs seta testes ee ntseesee 675 675 Indicated honse: pow Cri:.c- dey cartes dees cece ee 200 155 Type Gf Dover. 2h onceassacns.oseeeies mro-tacdop eres Tubulous, Steam pressure, WOMNAG.....,.cosccotce ect taceenas ten aereve 250 250 Grate: surface square tet, .csccs -tpesesecuenssene treed 12 9.25 Heatingisurfacessquare feet. .....ccts-segessthesegccsace 480 372 Weight of all machinery, including auxiliaries, water aNd SpareS, POUNGS............sccoecsecscscceeeeee 12,000 9,900 As already stated, each boat will have a single vertical quadruple expansion engine, working at 250 pounds pressure. The high pressure cylinder will be forward. The shafting and working parts generally will be of forged open hearth steel, and -- the piston and connecting rods will be oil tempered. 'The shaft- ing will be hollow. The framing will consist of forged steel columns stayed by diagonal braces, so as to give a firm support to the slides and make the whole structure firm and rigid. The engine bed plate is of plate steel, supported on keelson plates : built in the boat, and stiffened by an angle iron running fore and aft on each side of the engine. The engine is also stiffened by what might be called an overhead bed plate, in that the cylinders have the pairs whose cranks are opposite cast together, while they have the two pairs joined by an interlocking arrangement and secured by turned and driven bolts, making an exceedingly rigid connection. All of the cylinders except the low pressure will have piston valves, the low pressure having a double ported flat slide. 'The valves of the high pressure and first intermediate pressure will have no rings, while that of the second interme- diate will have a broad adjustable ring. The valve gear will be the Stephenson link motion. The most novel feature in these engines will be the air pumps, which are the design of Passed Assistant Engineer Frank H. Bailey, United States Navy, chief designer for the bureau of steam engineering. As is well known, it is generally considered the best practice to have the air pumps run ata comparatively low speed and to be of the single acting, bucket plunger type, so that it would hardly be thought possible that air pumps could be run efficiently from main engines at a speed of nearly 700 revo- lutions per minute. 'This, however, will be the case in these boats, for economy of both steam and space, as independent pumps, while highly efficient in securing a vacuum, are very wasteful of steam. 'The pumps are only 3 inches in diameter by 3% inches stroke, and each engine will have two of them driven fe an eccentric on the forward end of the shaft. The pumps are horizontal and double acting. The piston is solid and there are no foot valves, while the delivery valves cover the entire end of the cylinder, being held in place by alight spring. The open- ing for admission of water and air is at the middle of the length