AIR TEMPERATURE.
The most recent definition of heat is that it is a mode of motion; not
movement of a mass of substance, but movement of its ultimate particles.
It has been determined by experiment that the ability of any substance
to absorb heat depends upon the number of atoms it contains, rather than
its bulk or its weight.
It has also been stated that the atmosphere at sea-level weighs about
fifteen pounds to the square inch, which means that a column of air one
inch square extending from sea-level upward to the extreme limit of the
atmosphere weighs fifteen pounds. The density of the air decreases as we
ascend. Each successive layer, as we ascend, is more and more expanded,
and consequently has a less and less number of air molecules in a given
space. Therefore the capacity of the air for holding heat decreases as
we go higher.
We deduce from these facts that the higher we go the colder it becomes;
and this we find to be the case. Whoever has ascended a high mountain
has had no difficulty in determining two things. One is that the air is
very much colder than at sea-level, and the other that it is very much
lighter in weight. We find it difficult, when we first reach the summit,
to take enough of oxygen into our lungs to carry on the natural
operations of the bodily functions. To overcome this difficulty, if we
remain at this altitude for a considerable time, we shall find that our
lungs have expanded, so as to make up in quantity what is lacking in
quality.
If a man lives for a long time at an altitude of 10,000 feet he will
find that his lungs are so expanded that he experiences some difficulty
when he comes down to sea-level. And the reverse is true with one whose
lungs are adapted to the conditions we find at sea-level, when he
ascends to a higher altitude. There is a constant endeavor on the part
of nature to adapt both animal and vegetable life to the surroundings.
While no exact formula has been established as to the rate of decrement
of temperature as we ascend, we may say that it decreases about one
degree in every 300 or 400 feet of ascent. There is no exact way of
arriving at this, as in ascending a mountain the temperature will be
more or less affected by local conditions. If we go up in a balloon we
have to depend upon the barometer as a means of measuring altitude,
which, owing to the varying atmospheric conditions, is not a reliable
mode of measurement. It is easily understood that a cubic foot of air at
sea-level will contain a great many more atoms than a cubic foot of air
will at the top of a high mountain; or, to state it in another way, a
cubic foot of air at sea-level will occupy much more than a cubic foot
of space 10,000 feet higher up. Suppose, then, that the amount of heat
held in a cubic foot of air at sea-level remained the same, as related
to the number of atoms. In its ascent we shall find that at a high
altitude the same number of atoms that were held at sea-level in a cubic
foot have been distributed over a so much larger space that the sensible
heat is greatly diminished or diluted, so to speak. It was an old notion
that heat would hide itself away in fluids under a name called by
scientists latent heat. This theory has been exploded, however, by
modern investigation.
If we place some substance that will inflame at a low temperature in the
bottom of what is called a fire syringe (which is nothing but a cylinder
bored out smoothly, with a piston head nicely fitted to it, so that it
will be air-tight) and then suddenly condense the air in the syringe by
shoving the plunger to the bottom, we can inflame the substance which
has been placed in the bottom of the cylinder. In this operation the
heat that was distributed through the whole body of air, that was
contained in the cylinder before it was compressed, is now condensed
into a small space. If we withdraw the plunger immediately, before the
heat has been taken up by the walls of the syringe, we shall find the
air of the same temperature as before the plunger was thrust down. This,
however, does not take into account any heat that was generated by
friction.
Let us further illustrate the phenomenon by another experiment. If we
suddenly compress a cubic foot of air at ordinary pressure into a cubic
inch of space, that cubic inch will be very hot because it contains all
the heat that was distributed through the entire cubic foot before the
compression took place. Now let it remain compressed until the heat has
radiated from it, as it soon will, and the air becomes of the same
temperature as the surrounding air. What ought to happen if then we
should suddenly allow this cubic inch of air to expand to its normal
pressure, when it will occupy a cubic foot of space?
Inasmuch as we allowed the heat to escape from it when in the condensed
form, when it expands it will be very cold, because the heat of the
cubic inch, now reduced to the normal temperature of the surrounding
air, is distributed over a cubic foot of space.
This is precisely what takes place when heated air at the surface of
the earth (which is condensed to a certain extent) rises to the higher
regions of the atmosphere. There is a gradual expansion as it ascends,
and consequently a gradual cooling, because a given amount of heat is
being constantly distributed over a greater amount of space. At an
altitude of forty-five miles it will have expanded about 25,000 times,
which will bring the temperature down to between 200 and 300 degrees
below zero.
When we get beyond the limits of the atmosphere we get into the region
of absolute cold, because heat is atomic motion, and there can be no
atomic motion where there are no atoms.
We have now traced the atmosphere up to the point where it shades off
into the ether that is supposed to fill all interplanetary space. As
Dryden says:
There fields of light and liquid ether flow,
Purg'd from the pond'rous dregs of earth below.
By interplanetary space we mean all space between the planets not
occupied by sensible material. It is the same as interatomic space, or
the space between atoms, except in degree, as the same substance that
fills interplanetary space also fills interatomic space, so that all the
atoms of matter float in it and are held together from flying off into
space by the attraction of cohesion. What this ether is, has been the
subject of much speculation among philosophers, without, however,
arriving at any definite conclusion, further than that it is a substance
possessing almost infinite elasticity, and whose ultimate particles, if
particles there be, are so small that no sensible substance can be made
sufficiently dense to resist it or confine it. It is easy to see that a
substance possessing such qualities cannot be weighed or in any way made
appreciable to our senses. But from the fact that radiant energy can be
transmitted through it, with vibrations amounting to billions per
second, we know that it must be a substance with elastic qualities that
approach the infinite. Assuming that the ether is a substance, the
question arises how is it related to other forms of substance? This is a
question more easily asked than answered. The longer one dwells upon the
subject, however, the more one is impressed with the thought that after
all the ether may be the one element out of which all other elements
come.
Chemistry tells us that there are between sixty and seventy ultimate
elements. This is true at least as a basis for chemical science.
Chemical analysis has never been able to make gold anything but gold, or
oxygen anything but oxygen, and so on through the whole catalogue of
elements. It may be, however, that the play of forces under and beyond
those that seem to be active in all chemical processes and relations,
are able to produce certain affections of the ether, the result of which
in the one case is an atom of gold and in the other an atom of oxygen,
etc., to the end of the list. In this case all of the so-called elements
may have their origin in one fundamental element that we call the ether.
I am aware that we are wading in deep water here, but sometimes we love
to get into deep water just to try our swimming powers. The above is a
suggestion of a theory called "the vortex theory," that is taking root
in the minds of many philosophers to-day, and yet there is almost
nothing of known facts to base such a theory upon, and nearly all we can
say about it is that it seems plausible, when viewed through the eye of
imagination.
We do know that substances, such as fluids or gases, assume very
different qualities when put into different rates of motion. A straw has
been known to penetrate the body of a tree endwise by the extreme
velocity imparted to it when carried in the vortex of a tornado.
Instances of the terrific solid power of substances that are mobile when
at rest are often exhibited during the progress of a tornado, especially
when confined in very narrow limits. Sometimes a tornado cloud will form
a hanging cone, running down to a sharp point at the lower end, which
lower end may drag on the ground, or it may float a little distance
above the ground, but more frequently it moves forward with a bounding
motion, now touching the earth and now rising in the air. This cone is
revolving at a terrific speed. The substance revolving is chiefly air,
carrying other light substances that it has gathered up from the ground.
If it comes in contact with a tree or building it cuts its way through
as though it were a buzzsaw revolving at a high rate of speed. This is
not simply the force of wind, but a kind of solidity given to the fluent
air by its whirling motion.
I remember a case in Iowa, where one of these revolving cones passed
through a barnyard, striking the corner of the barn, cutting it off as
smoothly as though done with some sharp-edged tool, but it in no other
way affected the rest of the building. One would suppose that the
centrifugal force developed in this whirling motion would cause the cone
to fly apart, and why it does not no one certainly knows. But we are
obliged to accept the fact.
These cases are cited to show that motion gives rigidity to substances
that in the quiescent state are mobile or easily moved, like the straw
or the air. If we should assume that there are infinitesimal vortices or
whirling rings in the ether, of such rapidity as to give it different
degrees of rigidity, we can get a glimmering idea of how an atom of
matter may be formed from ether.
Referring to the rigidity which motion gives to ordinary matter, it is
well known that when two vessels at sea collide the one having the
higher speed is not so liable to injury as the one with the lower. The
reader will perhaps remember a circumstance said to have occurred a few
years ago on the Lake Shore Railroad, between Buffalo and Cleveland. The
limited express was going west, and while rounding a curve the engineer
suddenly came in sight of a wrecked freight train, a part of which was
lying on the track where the express train had to pass. The engineer saw
that he was too near the wreck to stop his train and that the only way
to save his own train and the lives of his passengers would be to cut
through the wreck. He pulled out the throttle and put on a full head of
steam, and when the train struck the wreck it was going at such a high
rate of speed that it cut through without seriously damaging the train
and without harm to the passengers.
There are other heroes beside those who lead armies in battle.