A valuable improvement in compressed air engines has recently been
patented in this country and in Europe by Col. F. E. B. Beaumont, of the
Royal Engineers, and we learn from accounts given in the London and
provincial papers that it has proved highly efficient and satisfactory.
The engine possesses some peculiar features which render it very
economical in the use of compressed air. It has two cylinders, one being
much larger than the other. Into the smaller of these cylinders the
compressed air is taken directly from the reservoir, and after doing its
work there it is discharged into the larger cylinder, where it is
further expanded, being finally discharged into the open air.
The admission of air to the smaller cylinder is regulated by an
adjustable cut-off apparatus, which admits of maintaining a uniform
power under a variable pressure. When the reservoir at first starting
contains air at a very high pressure, the cut-off is adjusted so that
the small cylinder receives a very small charge of air at each stroke;
when the pressure in the reservoir diminishes the cut-off is delayed so
that a larger quantity of air is admitted to the small cylinder; and
when the pressure in the reservoir is so far reduced that the pressure
on the smaller piston gives very little power, the supply passages are
kept open so that the air acts directly on the piston of the larger
cylinder. This arrangement is also available when the air pressure is
high and great power is required for a short time, as, for example, in
starting a locomotive.
It is, perhaps, needless to mention the advantages a motor of this kind
possesses over the steam locomotive. The absence of smoke and noise
renders it particularly desirable for tunnels, elevated roads, and, in
fact, for any city railroad.
Further information in regard to this important invention may be
obtained by addressing Mr. R. Ten Broeck, at the Windsor Hotel, New
York.
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