The Sun.
London, England, 1853-02-17 00:00:00

verton.

The author, in a short historical notice, stated tha,
Sir George Cayley had written on the subject in 1804
and 1807, and had subsequently built several engines ;
but that the. Messrs. Stirling, of Scotland, produced the
first really efficient engine, working by means of heated
air, in the year 1827. In the same year Messrs. Par-
kinson and Crosley brought forward their air engine ;
that Mr. Ericsson, following more closely the arrange-
ments and form of the ordinary steam engine, con-
structed an air or a " caloric engine," as it was termed,
in 1833. Messrs. Stiriing patented further improve-
ments in 1840, and in 1845 their engine was described
to and discussed at the Institution of Civil Engineers.
In 1851 Mr. Ericsson brought forward his present form
of engine, and that the principle acted upon in both
these latter inventions, and announced as an important
discovery in motive mechanics, was the reiterated use of
the same caloric in the production of power. The me-
chanical means of realising this idea were described, and
it appeared that in both inventions they were substan-
tially identical. The ejected hot air, by being brought
into contact with an extensive metallic surface of wire
gauze, was deprived of its heat, which the next moment
was imported to the incoming cold air, and thus the
ultimate use of the furnace was only to supply the un-
avoidable waste of caloric by radiation.
This view of the subject was strongly contested, as
being inconsistent with the best established laws of na-
ture, and as involving the idea of the possibility of the
creation of power. It was argued at some length, that
the employment of caloric as a motive agent consisted
in the development, from molecular forces, of a dynamic
force, and as such was directly amenable to the third law
of motion—that of action and reaction being equal and
opposite. It was contended that sensible caloric was
not an indication of the presence, but of the abeyance of
mechanical action ; that these were interchangeable con-
vertible quantities ; and, consequently, that a working
force could appear only as heat disappeared—a conclusion
entirely opposed to the assumed principle of the _" caloric
engine," that " caloric could be made to operate over
and over again." It was admitted, however, that there
was an apparent anomaly in the application of the law
of action and reaction when caloric was in question, in
the fact that its quantity was not less after than before
the generation of steam power, if it were estimated
conjointly by water and temperature. But it was ex-
plained that a cause might have two classes of effects,
and might require two distinct and different mea-
sures, to indicate its entire efficiency ; that while
caloric might remain intact, under the aspect ad-
verted to, it lost by a declination in the intensity of
temperature for which the equivalent gain was a dynamic
force—a conclusion as adverse as before to the idea
that such force could be acquired without cost. It
was, in short, in the aspect of a vis viva " force" in
caloric that the development of mechanical action must
be considered. These views were further explained and
illustrated by a reference to the analogous difference be-
tween momentum and the more practical modification
of power, named by Smeaton and Watt " mechanical
power," " work," and " duty ;" and it was shown that
here also an apparent discrepancy existed in relation to
the third law of motion, but which was cleared up when
both the measures of power—that by time and that by
space—were appropriately used.
It was contended that the "caloric engine" was
analogous to a non-expansive high-pressure steam-en-
gine, which it could exceed in wastefulness of heat, if
it were not provided with what its inventor improperly
termed a " regenerator," the office of which, it was in-
sisted, was simply to absorb the unutilised sensible
h
caloric of the escaping air, which, as comparedi with
steam, was in very large proportion to the efficient calo-
ric ; and to afford another opportunity of .t being con-
verted into force, thus compensatingfeufoeirdedtheenhe
loss
tosef
expansive pressure. An explanation,
considerations, was given of the continued action of the
engine for some time after the fire was wit awn—a
fact which had been advanced in support of what was a
styled the untenable hypothesis of a regenerator of
force."
Although the mechanical effect of heat might be proved
to be independent of the chemical condition, ndit was admitted
that ifnomtitatlesdo
of the physical constitution of bodies,
that economy of fuel, as being a distinct question from
that of economising the caloric already in possession, was
eminently a practical matter, only to be determined by
experiment ; and in this point of view it was explained
in what manner the reception of heat, at a much higher
temperature than steam, was greatly in favour of air as
a motive agent ; but, on the other hand, many adverse
considerations were adduced, tending to show the im-
practicability of the system in its present form.
In conclusion, it was shown that the other "caloric
engine" did not rest on true principles, exclusively its
own—that its merits stood upon common ground with
those of the steam engine--and therefore, that even
should the performances of air be found superior to those
of steam, it could not be anticipated that the former
would immediately supersede the latter ; but, as far as
public statements could be relied on, the performances of
the air engine on board the "caloric-ship " Ericsson,
were very unfavourable to the pretensions of the promul-
gators of the plan.
The discussion was commenced by an exposition of the
several systems adopted by Sir G. Cayley, Stirling, Park-
inson, and Crosley, and Ericsson, illustrating them by
diagrams, whence it appeared that the most preferable
mode of heating the air was that of Sir G. Cayley, by
directly traversing the incandescent fuel, that the great
improvement recently introduced by Ericsson was the
wire gauze regenerator, which, however, formed an al.