strictly adhered to in all engines giving above 8 B.H.P. The pistons are of unusual length and as light as possible.

The Richardson type of governor is used, and the side shaft is fitted with adjustable bearings; and all engines are arranged to run in either direction.

which, as the impulse is taken only on the outward stroke, may be light, and yet permit of very fine adjustment. The cranks are of the slotted form and balanced on the webs, a practice

In fig. 20, which is the form of engine used for the sizes ranging from 2 to 8 B.H.P, the only modification from that of fig. 19 is that the bed and base are in one casting, and the cranks are not balanced on the webs; and fig. 21 represents their smallest size of engine, on which an inertia governor of a simple form is substituted for the centrifugal one.

The tendency of all makers in designing large powers of gas engines is to arrange them in the girder form, and figs. 22, 23, and 24 are the elevation, plan, and perspective elevation of a 100 B.H.P. of this type.

Any part can be detached for examination and repairs without interfering with any other part of the engine, and readily put together again by means of a few turned bolts. The main girders are tied together by a large foot, yet, when completed, form a substantial structure, in which the strains are very evenly distributed. The governing gear has all the advantages of the centrifugal governor, and a broad striking edge, the disturbing action being practically nil. The combustion chamber is fitted with manholes, which, besides serving as a means of cleaning out the cores at the foundry, are useful, when bad water is used, in keeping the jacket face from mud, and the

FIG. 22.-100 B.H.P. ROBEY GIRDER TYPE ENGINE (ELEVATION)

FIG. 23.-100 B.H.P. ROBEY GIRDER TYPE ENGINE (PLAN)

covers being made specially thin, act as safety doors in case of frost.

The bearings are in four pieces, the adjustment of which is arranged by wedges on the side opposite which takes the explosion. The length of the centres of the connecting rod is not less than three times the length of the stroke, and as balanced cranks are used the strains are greatly reduced. Only one flywheel with barring teeth and a water trough (for testing purposes) is fitted; but an outer bearing and pedestal is provided, as the flywheel has to be of necessity very large and heavy. The crank is fitted with a neat arrangement of centrifugal lubrication for long-continuous running.

The Lanchester system is the method of self-starting used by this firm.