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238 THE MARINE REVIEW ------------ eee a AAA ee | Mr. CHARLES WARD. it. The .stern is. very. full. with a transom nearly full width of the boat to sustain the theavy stern wheel which is carried by wooden or iron beams, secured in pairs on the outer edges of the hull. One of these beams extends. ait of the hull to carry the large paddle-wheel; the other beam lays on deck on the extreme side of the boat. Each pair of these beams rests on about one-fifth of the length of the boat at the stern and takes bearing and support from the several frames they cover. A system of braces: connects the deck and floor frames and these beams together. This trussing forms the engine bed and. its foundation, : to which the entire engine, including cylinders, slides and shaft 'bearings is secured. While the whole thing looks, and is limber, it thas the ad- vantage of covering a large bearing on the water. The whole hull is to an easterner very fragile, but with careful loading, and the novel system of chaining and bracing, it' has met the' requirements of the case. In building the same form of hull in steel, efficient system of a much more bracing is necessary, as the same amount of flexibility would strain the seams and bring on trouble. Rudders. The rudders of a stern-wheeler, two or more, like everything else about the boat, are peculiarly suited to the conditions and are of the balanced type, the balance extending well under the stern of the boat, and the after end reaching out to, and just clear of, the wheel. Sometimes the rudder stock is vertical and the bottom of the boat formed to clear the rudder, but more generally the rudder is hung with the top of the post pitching for- ward, in which case the forward part of the rudder is formed to clear the boat. The peculiarity of the position of the rudders forward of the wheel was doubtless brought about by the difficulty of placing the rudders aft of the paddle-wheel. This peculiarity diminishes the power of the rudders when going ahead, but increases it when the boat is backing. While of- ten useful, this makes it necessary for the boat to stop and back in order August, 1909 to secure the desired position going forward. In towing, this peculiarity has proved quite useful. With a large tow, in short bends of the river, there is often not room enough to steer the tow around these curves; then it becomes necessary to stop and back strong, checking the Progress - down stream. At this time the ryuqd- ders are very powerful and move the stern of the boat sideways, while the current tends to move the head of: the tow in the opposite direction, and, at the same time, float it around the bend. This is called flanking, > Boilers. Boilers are sometimes tubular and occasionally of the locomotive type, but more generally of the cylindrical flue type, ranging in diameter from 30 to. 40..in., and in. length, from 15 to 30 ft. The generally accepted form is the two-flue type, with fluse rang- ing from 12 to 16 1n...in diame Wihen weight is of prime considera- tion, five or six flues are used. Flues are always riveted to the heads, even when a large number of small flues are used. When arranged in battery, which. is general, except in. very. small: boats, these boilers are connected together transversely by two mud drums _ under- neath and a steam drum above--all firmly riveted together, with tubular connections flanged and riveted to the boiler and the drums, making a com- mon water-line and one compact piece, which lays over a large area of the deck, covering a large number of deck frames and displacement. In this particular they are suited to the conditions, as their weight is dis- tributed over a large surface. Very heavy foundations are not required. Being externally fired, the fire-box and fire-bed are formed of sheet iron,- lined with firebrick, combustion chambers. The gases of combustion pass under the boilers and return through the flues to the 'breeching and smoke stack. The draft is increased by the exhaust from the engine or by steam jet blowers, which are fitted to each flue, however many there may be. I need hardly to Say that the very ex- travagant way of increasing combus- tion. ~ Steamboat think are the They are the accompanying conditions following reasons :-- with very slow latter 1s a flue boilers suited to for the men thing. Their simple construction keeps first cost down; their small diameter ad- mits of high-pressure steam without thick plates; they are accessible for cleaning and work muddy water fair-