MARINE ENGINES.

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blocks must be well executed, for the main stress is directly takenon these bearings. When the distance between the cylinders isgreat, leaving a long centre part on the cranked shaft between thecranks, the centre bearing should be increased in length, so that noundue strain is taken on the cranked shaft; in fact, the shaft shouldbe always supported as close to the cranks as is practicable. Allthe brass bearings are recessed for the reception of white metal,which is poured in while in a fluid state, a cast-iron core piece,somewhat less than the diameter of the shaft, being first inserted

Fig. 301.—Main Framing of Fox Section.

A, Frame, b, Brasses . c, Cap. x> d, Bolts and nuts. e, Wrought-iron stay. f, Slipper guide.

G, Oil cup.

in the bearing, so as to keep the white metal in its place; the halfbrasses are held together prior to this Operation, and are bored outin the lathe and then separated. In this way fair work is secured;but some makers prefer boring out the brasses in situ, and nodoubt when properly executed this plan has its advantages. Inmost machinery there are numerous fittings which can be con-veniently cast on the main framing, or bolted on fitting strips leftfor that purpose; and proper attention to these points shows theskilfulness of the designer, and saves much work afterwards.

The box form of framing differs materially from the x and +

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