British Admiralty.—Tensile, 58,240 to 67,200 lbs.; elongation in 8 in., 20 per cent. Same cold-bending and quenching tests as United States Navy.
Bureau Veritas,—Shell : Tensile, not less than 00, 480 lbs.; elongation in 8 in., 20 per cent ; must with stand after heating to dull red, and being plunged into water of 80° F., being bent until opening between ends is three times thickness of plate.
United States Revenue .Marine.—Tensile, not less than 60,000 lbs.; reduction of area, 50 per cent.
American Boller- Makers' Association.— Tensile, 55,000 to 65,000 lbs.; elongation in 8 in.. 20 per cent for plates ; in. thick and under; 22 per cent for plates in. to in. ; 25 per cent for plates in. and over. Cold bending test : For plates it in. thick and under, speci men must bend back on itself without fracture: for plates over 4 in. thick, specimen must withstand bending 180° around a mandril one and a half times the thickness of the [dote. Chemical Phosphorus, not over .040 per cent ; sulphur, not over -030 per cent.
FIRE -Tune Bommts.— The ReynoldsVertical Tabu tar Boiler, made by the E. P. Allis Co., of Milwaukee, is shown in Figs. 1 and 2. The tubes are set in rows radiating from a large man-hole located over the fire-door and bottom tube sheet, consequently every flue and all parts of both tube-sheets can be inspected and cleaned when the man-hole cover is removed. Iland-holes are located near the man-hole for ad mitting light for inspecting mid inserting a hose-nozzle for washing the tubes and crown sheet. Iland-holes are placed at intervals around the base, where sediment collected in the Nynter-legs may be removed. The feed water is pumped into the internal reservoir through the feed-pipe ; this reservoir being closed at the bottom. The discharge into the Loiter is over the top. and it being so much larger than the feed-pipe, the current npward is very slow. consequently the feed-water gains the same temperature as the water in the boiler before it is dis charged into the boiler, Tins action is effective in precipitating nearly all of the heavy impurities carried in with the feed-water, which can be blown out of the reservoir by a blow-off arranged for this purpose. By carrying the water in the boiler slightly above the top of the reservoir, it can then be utilized as a surface blow-off to free the boiler of scum or light impurities collected on the surface of the water. The smoke-hood on toll of the boiler is furnished with a revolving top having a removable cover. For the purpose of clean ing the fines this cover is removed, and only a small portion of the total number of flues are exposed at one time ; this arrangement en ables the fireman to clean the flues while the boilers are in operation. This type of boiler is especially adapted to locations where floor spaee is valuable, as from 300 to 400 horse-power of vertical boilers can be located in the space required by an ordinary horizontal tubu lar boiler of 100 horse-power capacity.
Vertical Boiler with Submerged Tubes.—Fig. :3 represents a vertical tubular boiler, built by the Morrisville Machine Works. Baldwinsville, N. Y. The upper ends of the tubes are
submerged in water, and are thereby prevented from burning out, obviating one of the prin cipal defects of the ordinary vertical boiler.
Payne's Vertical Tubular Boiler.—The boiler shown in Fig. 4, built by B. W. Payne & Sons, Elmira, N. Y., is also designed to prevent the burning out of the upper ends of the tubes. Midiyay between the outer tithes and the shell of the boiler is suspended a cylindrical baffle-plate—concentric with the boiler-shell. This baffle-plate, or apron, extends from about 11 in. below the upper head to within about 10 in. of the bottom of the water-leg of the boiler, and completely surrounding the tubes. Midway between this apron and the boiler-shell is suspended from, and joined to, the upper head a perforated plate, which extends downward about 20 in., encircling the apron. The effect produced by the apron and perforated plate is that when the boiler is subjectvd to heat from its furnace, the water surrounding the tubes as cends and is replaced by the cold water from the space between the apron and the boiler-shell. As the heat increases, the circulation around the apron becomes more rapid, the water within the apron and around the tubes being forced to and over the top of the apron where the separation of water and steam takes place ; the latter passing through the perfo rated plate to the space between the boiler-shell and that plate, and the former descending to the water contained between the apron and boiler shell. The steam is drawn from the boiler through an opening in the shell near the upper head. The separation of the water and steam is thorough, as the water after passing over the apron has a downward tendency, which, with its greater weight, causes it to descend ; while the steam readily passes through the perforated plate, and is found in the outer space free from entrained water.
Marine Boilers milk Corrugated all steam ers are now fitted with boilers of the Scotch type. Two of these boilers are shown in Figs. 5 and O. These boilers were made by Messrs. J. & G. Rennie, of London. The use of corrugated furnace-flues, or of some substitute for them, as flues with stiffening ribs, has become almost uni versal since the use of high pressures of steam 100 lbs. and upward. The marine boilers used in the United States gun-boats Yorktown, Concord, and Bennington, have each three corrugated furnace-flues leading into one common back connection. From here the products pass along through the nest of tubes to the chimney. The British Board of Trade in 1891 adopted a new formula for the working pressure allowable on corrugated furnaces, as follows: 14000 X T , in which WP is the working pressure in lbs. per sq. in., T thickness in., and D mean diameter in in. Lloyd's Registry have also adopted a new formula, as fol lows: in which T is the thickness in sixteenths of an in., and D the greatest diameter in in.