Plate XXXVI.Larger image
Plate XXXVI.
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TYPICAL PROPELLING ENGINES.Larger image
TYPICAL PROPELLING ENGINES.
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Many varieties and types of boilers have been made. The old practice of having two or three rings in the length of the shell in ordinary cylindrical boilers has long since given place to one plate in the length. The boiler ends are seldom made in more than two plates; up to diameters of 11 ft. only one plate is used. The number of riveted seams is thereby reduced to a minimum, and the liability of the boiler to leak is minimised. The Scotts also have a system of forced draught for supplying either cold or heated air to the furnaces, which is fitted largely to their ships, and gives every satisfaction. Large installations of Belleville and Yarrow water-tube boilers for working under forced draught have also been made and fitted in H.M. ships, but they need no description here. A large installation for burning oil fuel has recently been completed and applied by the firm to the Babcock and Wilcox water-tube, and the cylindrical, boilers of H.M.S.Argyll.