from Chemical Action, Combustion, etc. (2) From transmission or "contagion" from some other body of Substance, the Particles of which are vibrating at the rate of Heat. (3) From interrupted Motion, including friction both of the moving body with the air or other Substance, and the friction of a current of Electricity passing through the body. In each of the above cases, the actual and immediate cause of the Heat is the vibration of the Particles of the Substance manifesting the Heat, although the transmitted vibratory waves, or the interrupted motion, friction, current, etc., may have been the instigator or provoker of such vibration. The interrupted motion, friction, or "wave" does not produce the Heat, but merely arouses or provokes the increased vibration of the Particles, that really manifest the Heat. At the last, remember, the Heat is in the Particles of the body that "feels" or experiences it.
The vibrations of Heat seem to have the properties of causing the Molecules to draw further apart, and to manifest less Attraction, or more Repulsion, whichever way one cares to express it. This "moving away" of the Molecules tend to cause the body to increase in volume or size, and occasions what is known as "Expansion" in Substance. In this way Heat transforms Solids into Liquids; Liquids into Gases or Vapors, the change being wholly a matter of the relative distances of the Molecules.
Magnetism is another form of Energy, and is generally believed to be a part of the phenomena of Electricity, if indeed, not a form of Electricity itself. Science knows very little about the nature of Magnetism, but in a general way holds to the theory that it results from the vibration or motion of the Particles of Substance, as do all other forms of Energy. The magnetic qualities of a body may be increased or decreased by motion affecting the relation of the Molecules, which fact has been regarded as having some bearing on the theory.
Electricity is a form of Energy, that Science regards as also arising from the vibration or motion of the Particles of Substance. It is transmitted, like Heat, by Conduction and Radiation, the "waves" tending to provoke similar vibrations in the Particles of Substances receiving them. By many careful investigators, Electricity is believed to be very closely related to the phenomenon called light, both having much in common. Science seems to be discovering new points of resemblance between them, and it is probable that in the near future they will be seen to be but varying forms of the same thing. The purposes of this book do not call for an extended consideration of the properties of Electricity, the same being served by a consideration of its nature being akin to that of the other forms of Energy, namely, "vibration or motion in or among the Particles of Matter."
Light is a form of Energy, the study of which is of the greatest interest to Science, for the reason that the field seems to be widening out continuously, and reaching out into the territory formerly thought to be the special region of Electricity. And, in another direction, it seems to be reaching out into the territory of Heat, the latter being considered by many to be but a form of Light, in its lower vibrations. In fact, the writer of this book so considers the subject, and for the purposes of this book, in later chapters, he will combine Electricity, Heat, and Light, including, also, the phenomena known as the X-Rays, Becquerel Rays, Radium waves, etc., as forms of Light—the combined forms of Energy to be called "Radiant Energy." In this combination, he believes that he is in line with the latest and best thought of Modern Science. However, he does not insist upon his readers following this idea, and so, if they prefer, they may think of each of these forms as separate and distinct, and yet not run contrary to the line of thought of the book.
Light is not the simple thing that it is considered to be by the general public. It is composed of many parts, qualities and manifestations. Its rays, when separated by the Spectrum, are seen to consist of "waves" or vibrations of differing degrees of rate and intensity. The lower range contains the heat rays, and it is interesting to know that there are rays of heat too far down in the scale to be evidenced by human senses that may be distinguished by delicate instruments. But there are rays still further down in the scale that are known to exist, theoretically, that cannot be registered even by the finest instruments. To gain an idea of the delicacy of these instruments, let us remember that Prof. Langley has an instrument called the "Bolometer," that is so delicate that it registers a change of temperature of one millionth of a degree, and will register the heat of a candle one and one-half miles distant from it. Light vibrations arise from combustion, friction, electricity etc., causing the Particles to assume increased Motion.
Let us consider the report of the Spectrum. Beginning with waves or vibrations far below the sensibility of Man, the scale shows an advance until the first "warm" vibration of iron was reached. This first indication of warmth comes when the vibrations reach the rate of 35,000,000,000,000 per second. Then gradually they increase until a dull red glow is noticed—the lowest visible light ray—when the vibrations are 450,000,000,000,000 per second. Then come the orange rays, then the golden yellow, then the pure yellow, then the greenish yellow, then the pure green, then the greenish blue, then the ocean blue, then the cyanic blue, then the indigo, then the violet—the latter evidencing when the vibrations reach the rate of 750,000,000,000,000 per second. Then come the Ultra-violet rays—invisible to human sight—but evidenced by chemical media. In this Ultra-violet region lies the X-Rays, etc., and also the "Actinic Rays," that produce photographs, sunburn one's face and blister the nose—that cause violent explosions in chemicals—that transform forms of Substance—that are employed to cure skin diseases, etc. These Actinic or Chemical Rays have an important role to play in plant-life, for they act upon the green leaves of the plant, causing a chemical change by which carbonic acid and water are transformed into sugar and starches.
Some of the rays of the Ultra-violet region of Light penetrate substances formerly considered solid and impenetrable. And some of them emitted from Radium, etc., would destroy organic life if applied in sufficient quantities. Some of them are practically waves of Electricity so that Light and Electricity are seen to be closely related.
To give one an idea of the differences produced by different rates of vibration, let us imagine a Mass of Iron, shaped like a great "Top," capable of being impelled to "spin" at a constantly increasing rate of speed, by some Mighty Will. At first it is seen as a slowly spinning Top, manifesting nothing but slow motion, to our senses.
Now, imagine our Top spinning at a rate doubling each second. The first second the Top spins at the rate of two revolutions per second. We notice no change, except that we can see the movement. The next second the revolutions are doubled to four per second. Then, doubling each second, we have, respectively, revolutions of eight per second, then sixteen, and then in the fifth second thirty-two per second. Then we begin to notice a change.
When the revolutions reach thirty-two per second the friction of the moving Top on the air causes it to give forth a very low, deep, bass note of sound. This note is like a low, deep "hum," and is the lowest possible of perception by the human hearing, although it is possible that some of the lower forms of life may be conscious of still lower vibrations.
The sixth second the revolutions reach sixty-four, and the low note has grown much higher in the scale. The seventh second records a rate of 128, and the note has correspondingly increased. Then, as the seconds pass, we have, successively, 256, 512, 1,024, 2,048, 4,096, 8,192, 16,384, 32,768, the latter in the fifteenth second, and representing the highest note recognizable by the human ear, although it is believed that some of the lower animals may recognize sounds too acute for our sense of hearing. During this increase in revolutions from the fifth second to the fifteenth, the sound-note has risen rapidly in the scale from the low sullen "hum," on through the notes of the musical scale, and beyond the range of instruments, until the shrillness becomes so intense as to be almost unbearable, and finally terminating in a shrill, piercing shriek like the "squeak" of the bat, only long-drawn out.
Then from the termination of the sound (by reason of the rate of vibration having become too high) silence reigns for thirty seconds—absolute silence, in spite of the rapidly increasing rate of vibrations, in fact, because of it.
When the forty-fifth second is reached, and the revolutions have reached the rate of 35,184,372,088,832 per second, our Top begins to emit heat-rays, increasing each second. Then a little later a dull, dim glow may be noticed. Then, as the seconds fly, the dull glow manifests a deep dark red color, such as one notices in the iron of the blacksmith's shop, soon after it begins to "glow." Then, on