Lebon, in the certificate dated 1801, in addition to his first patent,
described and illustrated a three-cylinder gas-engine in which an
explosive mixture of gas and air was to have been ignited by an electric
spark. This is a curious anticipation of the Lenior system, not brought
out until more than fifty years later; but there is no evidence that
Lebon ever constructed an engine after the design referred to. It is an
instructive lesson to would-be patentees, who frequently expect to reap
immediate fame and fortune from their property in some crude ideas which
they fondly deem to be an "invention," to observe the very wide interval
that separates Lebon from Otto. The idea is the same in both cases; but
it has required long years of patient work, and many failures, to embody
the idea in a suitable form. It is almost surprising, to any one who has
not specially studied the matter, to discover the number of devices
that have been tried with the object of making an explosion engine, as
distinguished from one deriving its motive power from the expansion of
gaseous fluids. A narrative of some of these attempts has been presented
to the Societe des Ingenieurs Civils; mostly taken in the first place
from Stuart's work upon the origin of the steam engine, published in
1820, and now somewhat scarce. It appears from this statement that so
long ago as 1794, Robert Street described and patented an engine in
winch the piston was to be driven by the explosion of a gaseous mixture
whereof the combustible element was furnished by the vaporization of
_terebenthine_ (turpentine) thrown upon red hot iron. In 1807 De Rivaz
applied the same idea in a different manner. He employed a cylinder
12 centimeters in diameter fitted with a piston. At the bottom of the
cylinder there was another smaller one, also provided with a piston.
This was the aspirating cylinder, which drew hydrogen from an inflated
bag, and mixed it with twice its bulk of air by means of a two-way cock.
The ignition of the detonating mixture was effected by an electric
spark. It is said that the inventor applied his apparatus to a small
locomotive.
In 1820 Mr. Cecil, of Cambridge, proposed the employment of a mixture of
air and hydrogen as a source of motive power; he gave a detailed account
of his invention in the _Transactions_ of the Cambridge Philosophical
Society, together with some interesting theoretical considerations.
The author observes here that an explosion may be safely opposed by
an elastic resistance--that of compressed air, for example--if such
resistance possesses little or no inertia to be brought into play;
contrariwise, the smallest inertia opposed to the explosion of a mixture
subjected to instantaneous combustion is equivalent to an insurmountable
obstacle. Thus a small quantity of gunpowder, or a detonating mixture of
air and hydrogen, may without danger be ignited in a large closed vessel
full of air, because the pressure against the sides of the vessel
exerted by the explosion is not more than the pressure of the air
compressed by the explosion. If a piece of card board, or even of paper,
is placed in the middle of the bore of a cannon charged with powder, the
cannon will almost certainly burst, because the powder in detonating
acts upon a body in repose which can only be put in motion in a period
of time infinitely little by the intervention of a force infinitely
great. The piece of paper is therefore equivalent to an insurmountable
obstacle. Of all detonating mixtures, or explosive materials, the most
dangerous for equal expansions, and the least fitted for use as motive
power, are those which inflame the most rapidly. Thus, a mixture
of oxygen and hydrogen, in which the inflammation is produced
instantaneously, is less convenient for this particular usage than a
mixture of air and hydrogen, which inflames more slowly. From this point
of view, ordinary gunpowder would make a good source of motive
power, because, notwithstanding its great power of dilatation, it is
comparatively slow of ignition; only it would be necessary to take
particular precautions to place the moving body in close contact with
the powder. Cecil pointed out that while a small steam engine could not
be started in work in less than half an hour, or probably more, a gas
engine such as he proposed would have the advantage of being always
ready for immediate use. Cecil's engine was the first in which the
explosive mixture was ignited by a simple flame of gas drawn into the
cylinder at the right moment. In the first model, which was that of
a vertical beam engine with a long cylinder of comparatively small
diameter, the motive power was simply derived from the descent of the
piston by atmospheric pressure; but Mr. Cecil is careful to state that
power may also be obtained directly from the force of the explosion. The
engine was worked with a cylinder pressure of about 12 atmospheres, and
the inventor seems to have recognized that the noise of the explosions
might be an objection to the machine, for he suggests putting the end of
the cylinder down in a well, or inclosing it in a tight vessel for the
purpose of deadening the shock.
It is interesting to rescue for a moment the account of Mr. Cecil's
invention from the obscurity into which it has fallen--obscurity which
the ingenuity of the ideas embodied in this machine does not merit. It
is probable that in addition to the imperfections of his machinery,
Mr. Cecil suffered from the difficulty of obtaining hydrogen at a
sufficiently low price for use in large quantities. It does not
transpire that the inventor ever seriously turned his attention to the
advantages of coal gas, which even at that time, although very dear,
must have been much cheaper than hydrogen. Knowing what we do at
present, however, of the consumption of gas by a good engine of the
latest pattern, it may be assumed that a great deal of the trouble of
the gas engine builders of 60 years ago arose from the simple fact of
their being altogether before their age. Of course, the steam engine of
1820 was a much more wasteful machine, as well as more costly to build
than the steam engine of to-day; but the difference cannot have been so
great as to create an advantage in favor of an appliance which required
even greater nicety of construction. The best gas-engine at present made
would have been an expensive thing to supply with gas at the prices
current in 1820, even if the resources of mechanical science at that
date had been equal to its construction; which we know was not the case.
Still, this consideration was not known, or was little valued, by Mr.
Cecil and his contemporaries. It was not long, however, before Mr. Cecil
had to give way before a formidable rival; for in 1823 Samuel Brown
brought out his engine, which was in many respects an improvement upon
the one already described. It will probably be right, however, to regard
the Rev. Mr. Cecil, of Cambridge, as the first to make a practicable
model of a gas-engine in the United Kingdom.--_Journal of Gas Lighting_.
* * * * *
Alabama has 2,118 factories, working 8,248 hands, with a capital
invested of $5,714,032, paying annually in wages $2,227,968, and
yielding annually in products $13,040,644.
* * * * *