At a recent meeting of the _Société Industrielle_ of Elbeuf, Mr. L.
Quidet described an apparatus that he had, with the aid of Mr. Perré,
invented for evaporating juices.
In this new apparatus a happy application is made of those pipes with
radiating disks that have for some time been advantageously employed
for heating purposes. In addition to this it is so constructed as to
give the best of results as regards evaporation, thanks to the lengthy
travel that the current of steam makes in it.
[Illustration: PERRE & QUIDET'S EVAPORATING APPARATUS.]
It may be seen from an examination of the annexed cuts, the apparatus
consists essentially of a cylindrical reservoir, in the interior of
which revolves a system formed of seven pipes, with radiating disks,
affixed to plate iron disks, EE. The reservoir is mounted upon a
cast-iron frame, and is provided at its lower part with a cock, B,
which permits of the liquid being drawn off when it has been
sufficiently concentrated. It is surmounted with a cover, which is
bolted to lateral flanges, so that the two parts as a whole constitute
a complete cylinder. This shape, however, is not essential, and the
inventors reserve the right of giving it the arrangement that may be
best adapted to the application that is to be made of it.
In the center of the apparatus there is a conduit whose diameter is
greater than that of the pipes provided with radiators, and which
serves to cross-brace the two ends, EE, which latter consist of iron
boxes cast in a piece with the hollow shaft of the rotary system.
The steam enters through the pipe, F, traverses the first evaporating
pipe, then the second, then the third, and so on, and continues to
circulate in this manner till it finally reaches the last one, which
communicates with the exit, G.
Motion is transmitted to the evaporator by a gearing, H, which is
keyed on the shaft, and is actuated by a pinion, L, connected with an
intermediate shaft which is provided with fast and loose pulleys.
The apparatus is very efficient in its action, and this is due, in the
first place, to the use of radiators, which greatly increase the
heating surface, and second, to the motion communicated to the
evaporating parts. In fact, each of the pipes, on issuing from the
liquid to be concentrated, carries upon its entire surface a pellicle
which evaporates immediately.
The arrangement devised by Messrs. Perré and Quidet realizes, then,
the best theoretic conditions for this sort of work, to wit:
1. A large evaporating surface.
2. A very slight thickness of liquid.
3. A constant temperature of about from 100° to 120°, according
to the internal pressure of the steam.
Owing to such advantages, this apparatus will find an application in
numerous industries, and will render them many services.--_Revue
Industrielle._
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"FLYING."
_To the Editor of the Scientific American:_
Your correspondent on this subject in the issue of April 14 cites an
array of facts from which it would seem the proper conclusions should
be inferred. I think the whole difficulty arises from a confusion of
terms, and by this I mean a want of care to explain the unknown
strictly in terms of the known; and I think underlying this error is a
misconception as to what an animal is, and what animal strength is,
only of course with reference to this particular discussion, i.e.,
in so far only as they may be considered physical organisms having no
reference to the intellectual or moral development, all of which lies
beyond the sphere of our discussion.
Purely with reference to the development of physical strength, which
alone is under consideration, any animal organism whatsoever must be
considered simply in the light of a machine.
A compound machine having two parts, first an arrangement of levers
and points of application of power, all of which is purely mechanical,
together with an arrangement of parts, designed, first, to convert
fuel or food into heat, and, secondly, to transform heat into force,
which is purely a chemical change in the first instance, and a
transformation of energy in the second. So much for the animal--man or
beast--as a machine physically considered.
What then is animal strength considered in the same light? The animal
is not creative. It can make nothing--it can only transform. Does it
create any strength or force? No. The strength it puts forth or exerts
is merely the outcome of this transformation, which it is the office
of the machine to perform.
What do we find transformed? Simply the energy, or potential,
contained in the fuel or food we put into the machine. Its exact
equivalent we find transformed to another form of energy, known as
animal strength, which is simply heat within the system available for
the working of its mechanical parts. How, then, is this energy which
exists in the shape of animal strength used and distributed? This is
the question the answer of which underlies this whole discussion as a
principle. It is distributed to the different parts of the machine in
proportion to the relative amount of physical work that nature has
made it the office of any particular part to perform.
Let us see how it is with the bird machine. In course of flight he is
called upon to remain in the air, which means that should he cease to
make an effort to do this, i.e., should he cease to expend energy in
doing it, he would fall during the first second of time after ceasing
to make the effort some sixteen feet toward the center of the earth.
But he remains in the air for hours and days at a time. What is he,
then, doing every second of that time? He is overcoming the force of
gravitation, which is incessantly pulling him down. That is, every
second he is doing an amount of work equal to his weight--say 10 lb.
multiplied by 16--say 160 lb. approximately; all this by beating the
air with his wings. Now let us institute a slight comparison--and the
work shall be performed by a man, who climbs a mountain 10,000 feet
high in 10 hours. The man weighs 150 lb.; he climbs 10,000 feet;
1,500,000 foot pounds is, then, the work done. He does it in 10 hours,
or 36,000 seconds, which gives an amount of work of only 42 foot
pounds per second performed by his muscles of locomotion.
At the end of the ten hours the man is exhausted, while the bird
delights in further flight. To what is this difference of condition
due? _It is due simply to the difference in the machine;_ but this,
you say, is not explaining the unknown in terms of the known. Let us
see, then, if we cannot do this. In the two accounts of work done as
above cited in the case of the man and the bird, an amount of energy,
i.e., heat of the system, has been expended just proportional to the
work done.
Now while the bird has expended more energy in this particular work of
locomotion than has the man, we find the bird machine has done little
else; he has consumed but little of his available heat force in
exercising his brain or the other functions of his system, or in
preserving the temperature of the body, and but little of his animal
heat, which is his strength, has been radiated into space. In short,
we find the bird machine so devised by nature that a very large
proportion of the available energy of the system can be used in
working those parts contrived for locomotion, and resist the force of
gravity, or, what is the same thing, nature has placed a greater
relative portion of the whole furnace at the disposal of these parts
than she has in man. The breast muscles of the bird are so constructed
as to burn a far greater proportional amount of the fuel from which
all energy is derived than do the muscles of the rest of the body
combined.
Let us see how it is with the man who has climbed the mountain. In
this machine we find affairs in a very different state. During his
climbing he has been doing a vast amount of other work, both internal
and external. His arms, his whole muscular system, in fact, has been
vigorously at work, all drawing upon his total available energy. His
brain has been in constant and unremitted action, as well as the other
internal organs, which require a greater proportional amount of energy
than they did in the bird. Besides this, he has been radiating his
animal heat into space in a far greater amount. All these parts must
be supplied; they cannot be neglected while the accumulated surplus is
given to the machinery for locomotion or lifting. This then is what
constitutes what I call the difference in the machine, which is purely
one of organic development depending upon the functions nature has
determined that the different organs shall perform. As for the
pterodactyl quoted in the last article, I have only to remark that
this discussion arose purely from a consideration of what was the best
type of flying apparatus nature had given man to study, and I claim
that this prehistoric bird of geology does not come within this class.
For if it is not fully established that this species had become
extinct long before the appearance of man on the globe, it is at least
certain that the man of that early day had not dreamt of flying and
was presumably content if he could find other means to evade the
pterodactyl's claw.
F.J.P., U.S. Army.
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