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July, 1910 TAE Marine Review STEAMER NAPA VALLEY, OF THE' MONTICELLO STEAMSHIP Co.'s FLEET. bearings lined with white metal. The main bearing binder bolts are fitted with graduated nuts. Balanced slide valves are used on the low pressure cylinders and the high pressure and intermediate cylinders are fitted with piston valves working in cast iron liners. The valve gear is of the usual double-bar link type. Piston rods are of nickel steel, 54% in. diameter and are interchangeable and fitted with Wat- son metallic packing. Connecting rods are of the forked type, 75-in. centers, the top end fitted with bronze boxes and the lower end with steel boxes lined with white metal. Cross-head pins are 714 x 6% in. The crank shaft is solid forged, 11% in. in diameter, and made in two sections, with the cranks in each section placed at 180 degrees; the line shaft is 11 in. diameter and the propeller shaft 1134 in. diameter. The propeller is sectional with cast iron hub and cone and bronze blades. The stern tube is of the usual type, of cast iron, with composition liners fitted with lignum vitae staves. gine is of the ordinary direct steam type, with floating valve gear. A two- cylinder, 4 x 4 in. turning engine and Tatchet hand gear are also fitted. The four single-ended boilers are set In two batteries facing each other fore and aft, with fire room between. Oil fuel is used exclusively. The boilers are 12 ft. 3 in. diameter, 11 ft.. long between heads and contain three 34-ini, Temovable, suspension type furnaces with common combustion chambers. There are 322 21%4-in. tubes, 7 ft. °6 in. long, and every fourth tube in both vertical and horizontal rows is a stay tube. The heating surface in each boiler is 1,970 Sq. ft. The boilers are designed for a Working pressure of 180 Ibs. A fuel oil tank with a capacity of The reversing en-_ oe WHUUSAMOnNNEOTOOEET PEEP EEE PERE RE DEM 26,500 gal. is fitted directly forward of the boiler room. The surface condenser is independent and the cooling surface 4,250 sq. ft. The circulating pump is of the centri- fugal type, with a capacity of 4,000 gal. per minute. The air pump .is of the Blake vertical simplex type, 14 x 24 x 18 in. and fresh water pumps are also fitted. » One 7-K. W. and one 20-K. W. G-E turbo-generators supply current for about 325 incandescent lamps and one standard search light. The usual call bells, speaking tubes and telegraphs are fitted throughout. Altogether the Napa Valley is one of the best examples of a passenger steamer on the Pacific coast, and it is claimed that on her trial trip she attained a speed of 20% statute miles per hour. FACTORS CONTRIBUTING TO SPEED IN SHIPS. There is a chapter in Brassey's Naval Annual on engineering problems, and Alex. Richardson, who contributes it this year again, has been able, in a com- plete thesis on the "Efficiency of the Factors Contributing to Speed in Ships," to afford information regarding the de- velopment of the moment. He pleads for a fuller measure of efficiency in speed, contending that engineers are now beginning to realize more fully that what must be aimed at is not the best results of the boiler, engines, or propeller separately, but the efficiency of the whole combination, taking into account the proportions of the hull for a given displacement, the lines of the ship, the quality of the coal, the evapora- tion of the boiler, provision against heat radiation from the pipe connections, the thermo-dynamic efficiency of the turbines and the auxiliaries, the value of high power required Independent feed, fire, sanitary 'per ton displacement. A ' ' i vacua, and the efficiency of the propel- ler. oe He shows that the steady development in the length of battleships and cruisers has conduced to higher speed. | A caré- ful estimate of the probable: effective for overcoming the resistances in a 27-knot ship shows that, in a véssel of 530. ft. long between pet- -pendiculars, and of 17;250 tons displace- 'ment (like the. Invincibles), the power required to overcome skin-friction resist- ance is equal to about 0.84, and that to meet residuary resistance to about 0.85 effective .horsepower per ton displace- "ment; whereas in the latest British cruisers of 660 ft. long between perpendiculars and 26,350 tons displacement--these figures may be 0.75 and 0.68 respectively per ton displacement, a saving of about 15 per cent in the total effective horsepower As confirmation of this, it is stated that had the Lusi- tania and Mauretania been 700 ft. long instead of 785 ft., the: power necessary to attain their speed would have been at least 10 per cent greater. Data are given regarding trials of the Parsons partial-admission turbines, wherein it is shown, by comparison with an ordinary high-pressure cruising tur- bine, that the increase in the total power of a ship for the same quantity of steam is-about 7.per cent. This is. sure to -be improved upon with experience. But perhaps of greater interest is the prac- tice of fitting an impulse first-stage wheel in combination with reaction blading in turbines, as there is a great possibility of increased economy, espe- cially at low powers, by such a combina- tion, while at the same time greater sim- plicity and strength in manufacture is achieved than with compound-impulse turbines as fitted to each shaft in some European ships. For the lower powers