IMMENSITY AND COMPLEXITY OF NATURE.

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framed in accordance with intelligent design, nothing in it is essentially inscrutable to intellectual powers, and that the vast expanse of truth which remains unknown is only temporarily inscrutable, until the prior knowledge necessary to its discovery is obtained. And as ceaseless activity is a necessary condition of human existence, we may also conclude that new and improved intellectual processes of research will be invented, and that the entire universe of scientific truth will be investigated and discovered.

CHAPTER IV.

THE IMMENSITY AND COMPLEXITY OF NATURE.

SIMPLICITY, whether truthful or not, is often attractive to unphilosophical minds, because it requires less intellectual exertion. Men like to believe that the universe is framed in accordance with their own simple and crude preconceived ideas. As the human mind can think erroneously, it is only to a limited extent a true mirror of external nature. Realities often differ greatly from appearances, and the universe of matter is probably almost infinitely greater and more complex than our common ideas of it. The range of nature is inconceivably great. We cannot even imagine bounds to duration or space, nor do we know of limits to the amounts of matter or force, or to the degree of complexity of physical or chemical actions, except those already referred to (see Chapter II.). To say that duration is finite is equivalent to saying there was a period when time was not; and to say that space is not infinite is equal to affirming that there is a place where space does not exist. Geological considerations and

the phenomena of ancient eclipses carry us back towards periods of immense duration; those of astronomy and the revelations of the telescope indicate to us unlimited space; the spectroscope points towards the universal distribution of matter; the phenomena of nature show no definite limits to the quantity of energy; and the microscope and the phenomena of physics and chemistry reveal to us an almost infinite degree of minuteness in the constitution of substances, and complexity in the action of their forces.

The number of species of plants and of insects at present known has been estimated at 100,000. The stars of the firmament cannot be counted, because they exist in myriads; 200 millions of meteors are estimated to enter our atmosphere every twelve hours, and Arago calculated that 67 millions of comets frequent the planetary orbits. We know that the multitudes of lifeless substances in nature are actually innumerable; even the smallest grain of sand appears in the field of a powerful microscope like a mass of rock, and therefore composed of an immense collection of smaller particles. As extensive a world of minute things lies beyond the present reach of the microscope as that which that instrument has already revealed Notwithstanding the immense number of facts which differ in kind, the number of those which differ in degree is almost infinitely greater, because they shade off into each other by insensible differences. The number of modifications in the quantitative varieties of substances and forces appears to be limitless; even the number of possible mixtures of liquids, or of metals alone, is almost incalculable.

to us.

Berthelot has calculated the number of combinations which may be made of acids with certain alcohols, and says, If you give each compound thus possible a name,

IMMENSITY OF SPACE.

31

and allow a line for each name, and then print one hundred lines in a page, and make volumes of one thousand pages each, and place a million volumes in a library, you would require fourteen thousand such libraries to complete your catalogue.'

The portion of space we are at present acquainted with is immense, and altogether beyond our powers of conception. A cannon-ball, moving at its usual velocity, would occupy about a year in travelling from the earth to the sun, or more than 200,000 years to the nearest fixed star. Some of the distant heavenly bodies are so far off that light, travelling at the rate of 192,000 miles in a second, occupies more than 2,000 years in passing from them to us; and, for aught we know, there may exist multitudes of systems of worlds immensely more distant than this; and, notwithstanding that light travels at so enormous a velocity (nearly 900,000 times faster than sound), the speed of gravity, according to Laplace, is at least 50 million times greater.

It has been calculated by Sir William Thomson that the number of molecules in a single cubic inch of any gas is about 100,000 million million millions. Each molecule also, in different gases, consists of from two to many atoms, and is believed to be continually moving to and fro at a very rapid rate: in hydrogen, at about 6,055 feet per second, or 69 miles per minute (Joule). The diameter of a particle of matter has been estimated to be about to 3 millionth of an inch. According to Sorby,' ath of an inch cube of liquid water contains about 3,900 million million molecules. moon's influence upon the tides of the earth is about 21,871,400th part of the total influence of gravity, yet the

1 Nature, Feb. 24, 1876, p. 333.

The

latter force is a very feeble one in comparison with the other powers (see page 24); it requires the mass of the entire earth in order to attract an ounce with the force of an ounce, whilst a magnet may be made to attract and support many times its own weight. The heat evolved by the sun is calculated to be 2,000 million times as great as that received by the earth from it; and the light to be 300,000 times greater than that of the moon, or 2,200 million times more intense than that of a Centuari. Lalande calculated that it would require more than 17 millions of millions of years to bring about the contemporaneous conjunction of the six great planets.

"The amplitude of the aerial particles' (of soundwaves) is less than a 10-millionth of a centimetre.' A wave of light does not exceed 150,000th of an inch in breadth. In perceiving the sensation of violet colour, 707 millions of millions of vibrations are communicated to our eyes in one second of time.2 The least ray of light also, falling upon a coloured or dark body, is absorbed, and must produce some effect; and the effect is probably more or less different in every different substance, and in the same substance at every different temperature. In a vacuum it repels bodies, in black substances it produces heat, in selenium it alters the electric conductivity, in salts of silver it changes the chemical state, and so on. It has been truly remarked, 'There is every reason to believe, from the spectra of the elements, and from other reasons, that even chemical atoms are very complicated structures. An atom of pure iron is probably a vastly more complicated system than that of the

1 Lord Raleigh, Proceedings of the Royal Society, vol. xxvi. p. 248. 2 Young's Lectures on Natural Philosophy, ii. 267.

COMPLEXITY OF MATTER.

33

planets and their satellites.'1 According to Ångström and Thalen, pure iron ignited to whiteness simultaneously emits rays of light of more than 460 different rates of vibration; and titanium emits even a very much larger number.

Heat or pressure applied to a piece of steel alters its length, breadth, thickness, molecular arrangement, atomicdistance, specific gravity, cohesive power, adhesion to liquids, elasticity, temperature, specific heat, latent heat, thermic conductivity, thermo-electric power, electric-conduction-resistance, magnetic capacity, chemical and chemico-electric actions, and a number of other properties simultaneously. In a paper on The Molecular Movements and Magnetic Changes in Iron at different Temperatures,' 2 I have remarked, 'The changes produced by heat in even so apparently simple a substance as iron were so numerous in some of the experiments as to produce the impression that the metal was endowed with vitality.' This simultaneous change of properties is a general attribute of matter, and iron and the magnetic metals generally are only conspicuous instances of it amongst elementary bodies, probably because they possess the greatest number of molecules in a given space, and have their properties thereby condensed.

The phenomena of light and sound teach a similar lesson. Although the atmosphere is substantially a mixture of only two simple gases, the smallest portion of it is capable of transmitting at the same instant, with but little interference, not only an almost infinite number of rays of light of every different degree of refrangibility, but also millions upon millions of acoustic vibrations emitted

1 Jevons's Principles of Science, vol. ii. p. 452.

2 Philosophical Magazine, September, 1870.

D