OSCILLATING ENGINES. 243

some instances an intermediate or alternateconnection only is requisite ; and short arms,from the inner to the outer ring, complete theentire frame. This latter arrangement isoften used with fixed floats, and also in somecases with the feathering floats. With those,in some instances, the outer ring is dispensedwith, and the projections on the arms, alone,support the floats and requisite details. This,however, is not to he universally recommended,although material and labour are reduced byits adoption.

With reference to the centre pieces, theyare generally as these shown by Figs. 70and 72—pages 240 and 242. The mode ofsecuring them on the shaft is by keys, and, insome instances, lateral displacement is guardedagainst by a plate secured by studs at the

end of the shaft—also shown by Fig. 72.The means for turning the engines when“cold,” or not under steam, is by securinga toothed ring to the outer or inner ring—but mostly the former; and an ordinarypinion gearing with the same, imparts therequired motion by hand power—the handlebeing beyond the deck side of the paddle-box.

It is of course known to all engineers,'thatdesign, and even arrangement, is subject tothe power to be exerted; and the mode ofconnection, with a small example, will admit ofvarious modes not applicable in a large type.It is for this reason, mostly, that such trivialalterations and - variations are in being, notbeing therefore as much thoughts of capriceas ideas of circumstance.

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