The advantages of mechanical power have never been more appreciated
than at the present time, when trade depression enforces economy in
every industry and branch of production. Attention has accordingly
been keenly directed of late towards that class of prime movers
known as ‘small motors,’ deriving their power either from some
central supply, or themselves generating the motive energy. A wide
field undoubtedly lies open to such motive force, not merely in the
domestic operations—pumping water for house-supply, driving, sewing,
and culinary machinery—but also in such industrial work as cutting,
chopping, grinding, churning, and sawing; in addition to the numberless
requirements of the smaller manufactories and workshops.
Gas-engines have already reached a high stage of perfection, and in
towns where gas can be procured at a moderate cost, large numbers
of these motors are actively and advantageously employed in the
various operations just enumerated. The production of the gas at one
central source, prior to its distribution, is, it may be remarked, on
economical grounds, a very perfect arrangement, for the loss incidental
to a series of small producers is avoided. A similar law holds true of
steam, it being well known that a number of small engines driven from
one large boiler give a considerably higher duty than if each engine
had its own small boiler.
The employment of water-pressure has of late received considerable
impulse; and in large cities, systems of high-pressure supply are
now laid down. The power is supplied from accumulators worked by
pumping-engines at central stations, and a pressure of one thousand
pounds per square inch is not unfrequently maintained in the mains. For
lifts and hydraulic hoists, this system of transmitting power has been
eminently successful; for other purposes, it has not as yet realised
the expectations of its introducers, mainly, it is asserted, from
difficulty in obtaining a satisfactory motor which shall transform the
pressure into motion.
Cost of production has as yet debarred electricity from competing
commercially as a transmitter of power; viewing, however, the
extraordinary progress recently made, it would be rash to assert how
much further a comparatively near future may not bring us, if we would
read the future by the past.
Recently, a vacuum-engine has been produced, which attracted
considerable attention at the Inventions Exhibition, and from what
has been achieved in a very short time, promises well. Amongst the
advantages claimed for this engine is the fact that once started, no
further attention is requisite for many hours. By an ingenious use
of gun-metal in the cylinder, valves, &c., lubrication is rendered
unnecessary; whilst, by means of a hopper boiler, the furnace is
self-feeding. Explosion is, of course, impossible, the engine working
below atmospheric pressure.
This engine has been employed in small electric-light installations;
and from its regular motion and the ease with which it is managed,
is undoubtedly eminently adapted for this class of work; whilst the
smallness of its coal-consumption and the high duty attained have
procured the highest awards at the hands of all juries who have
examined it.
In the future of ‘small motors,’ a future that appears an extended one,
this new vacuum motor will doubtless play a not unimportant part.