WATER-TUBE BOILERS.—The Ileine Water-Tube Boiler (Fig. 9).—The distinguishing. features of the Ileine boiler as compared to other water-tube boilers are briefly these : 1. It is an entirely riveted construction, with no bolted joints to work loose. 2. While it has the same principle of action as other water-tube boilers, viz., a rising current of steam and water mixed in front, and a falling current of solid water in the rear, it differs from them in having the throat opening from 65 to 90 per cent of the total cross-sectional tube area. 3. The travel of the gases is horizontal with a gradual upward trend, as distinguished from the np and down travel of the gases in the older types of water-tube boilers. 4. The water-legs being the strongest parts of the boiler, form its natural supports. the front one resting on a fixed fire front, the rear one on expansion rollers on the rear wall. 5. The internal mud-drum (inclosed inside of the steam and water drum) forms a receptacle in which the feed-water is gradually heated to approximately the temperature of the water in the boiler, and as it issues from the front top of the same in a thin current, it mixes with the main current flowing backward in the shell, and the expansion strains from changes in temperature are practically eliminated. 6. Access is given to the outside of the tubes through hollow stay-bolts in the water-le!_rs at all times, so that the tube-heating surfaces can be inspected, cleaned, and watched while the boiler is under steam. 7. All the hand-hole plates opposite ends of tubes have internal joints, thus doing away with the danger resulting in other types from broken bolts in the headers. 8, The mode of setting practically prevents the flame or hot gases from striking the riveted work of the shell, until their temperature has been reduced to about 900° F.. or less.
Gill's Water-Tube Poilen—The Gill boiler, Fig. 10, is a representative of a number of new water-tube boilers that have. come into use during the past ten years, of the general type which has become standard, and apparently permanent, having a dram in which the water-level is carried at or near the middle, and a bank of inclined tubes connected with headers, which are connected by eireulat MI; pipes to the drum. The Gill boiler differs from other boilers of this standard type merely in the details of construction of the headers.
and in its method of connecting the headers to the drum. These details are shown in Figs. 9
and 10. The water-tubes, 4 in. in diameter and spaced about 3 in. apart, are inclined at an angle of about 15° from the horizontal. Each nest of 4 or 5 tubes is expanded into a east-iron box or header at each end in such a way that the tubes are staggered instead of being placed one above the other. By thus making these boxes short, and by connecting them by slightly flexible tubes, the danger of breakage is entirely avoided, which is of common occurrence where the headers are made in one long cast-iron box. The connection between the headers and the steam and water drum overhead is exceedingly simple, consisting of short tubes which are expanded into the top of the headers and into the drum entering the latter radially, for which pur pose they are curved to the proper form. l•ig. 11 shows a bank of headers and a steam-drum with their connections.
Yarrow's Water-Tube Boiler.—Fig. 12 shows a type of water-tube boiler which has been lately introduced by Messrs. Yarrow & Co., for use in the torpedo-boats built by thh firm. There is a horizontal upper chamber or receiver and two lower chambers, each of the latter occupying the space at the sides of the fire-grate. The receiver is connected tc the lower chambers by numerous straight lengths of pipe. composed of weldless-steel tube, The parts of the chambers into which these tubes arc inserted are flattened so that several rows of the tubes are possible. The tubes are expanded into the chambers in the ordinary way. Each chamber is made in two parts, which are flanged out and joined by nuts and bolts, a copper wire serving as packing to make a steam-tight joint. The water-gauge glasses and other fittings are attached to the upper cylinder. The whole is inclosed by a smoke• jacket, and the products of combustion pass upward among the tubes to the uptake on the top of the boiler. The length of the cylinders is about 6 ft., and the diameter of the toi receiver is 20 in. The tubes are galvanized, and arrangements have been made whereby the whole of the boiler can be galvanized complete. When running. the water-level is kept about half-way up the receiver. The advantages claimed for the boiler are that it is free from com plicated and intricate parts, there being neither bends, elbows, nor intermediate obstruction to the free flow of steam and water through the tubes.