Next to the fallacious testimony of the human senses, and the hidden nature of material substance, the subtle influences at work in the physical world seem very remarkably to indicate some curious analogies between the constitution of matter in its finer forms, and the nature of spiritual agencies. Recent analysis of the solar beam, for instance, has revealed rays hitherto unknown, because invisible to the acutest vision unaided by the appliances of science, and for long concealed even from its piercing scrutiny, but yielding at last to the refinements of modern investigation. These invisible rays have been proved to exercise most important functions in nature; in the germination and vegetation of plants, and other widely multiplied physical processes. There are few who have not heard much of the magnetic and electric currents which permeate every portion of the surface of the globe and its surrounding atmosphere; but we imagine that not so many are aware of the powerful influence which they possess in the economy of our planet. "There is strong presumptive evidence," says Mrs. Somerville, "of the influence of the electric and magnetic currents on the formation and direction of the mountain masses and mineral veins; but their slow persevering action on the ultimate atoms of matter has been placed beyond a doubt by the formation of rubies, and other gems, as well as various other mineral substances by voltaic electricity." [Footnote 128] And, in another place, in the same instructive work, she remarks, that "it would be difficult to follow the rapid course of discovery through the complicated mazes of magnetism and electricity; the action of the electric current on the polarized sunbeam, one of the most beautiful of modern discoveries, leading to relations hitherto unsuspected between that power and the complex assemblage of visible and invisible influences on solar light, by [{379}] one of which nature has recently been made to paint her own likeness." [Footnote 129] These influences, for all their subtlety, have a real, appreciable existence, and fulfil a definite and beneficent end. A curious example of the subserviency of the invisible magnetic current to the wants of men is mentioned by Humboldt as having occurred to himself, in one of his voyages off the west coast of South-America. Bad weather had prevailed for several days, so as to shut out all view of land, or of the sun and stars. The crew were in expectation of making a particular port on that coast: on consulting his dip-needle, the scientific passenger discovered that the ship had passed the latitude of its destined port; the ship's course was altered, and much delay and, probable, danger avoided. [Footnote 130] Nor are the agencies destructive to human life less subtile or recondite. Various miasmata of a pestilential character defy every refinement of chemical analysis to detect the cause of their mischievous operation, or the difference of their elementary constitution from that of pure and wholesome air. The most universal, and, as far as our knowledge serves, the most important of all physical influences, that of gravitation, is also the subtlest and most occult; traversing the vast regions of space with instantaneous speed, and pervading the remotest fields of the great universe of matter; penetrating without sensible interval of time to distances far beyond the utmost reach of human thought, with a force which maintains the stars of heaven in their courses, and gives stability to every known material system.
[Footnote 128: Physical Geography, II., chap. xxii. pp. 92.]
[Footnote 129: Physical Geography, II., xxxiii. pp. 400, 401.]
[Footnote 130: Cosmos, I. 171; III. 139.]
If these occult agencies in the material world are recognized as fulfilling their mission, for all their secrecy and subtlety, or rather, by means of these very characteristics, why is the possibility of a hidden yet efficient agency in the spiritual world denounced as a heresy against common sense and sound philosophy? The physical system of things has its great laboratory of decomposition and reconstruction kept in operation by these unseen influences; it is indebted to them for the maintenance of its existence. Science rejoices to measure them by their admirable results, to detect their operations in their sensible effects. Why must the sacramental system revealed in the spiritual world be with equal justice refused its claim to an agency hardly more subtle? Philosophers admit the truth of observations in these occult natural agencies, and have no doubt of their real existence; why do they so contemptuously regard the result of our observations in those which are secret and spiritual, when our observations are as numerous, and their evidence as good?
IV.
The whole question of the relation of space and time becomes one of vast interest and importance, in connection with a common objection made to the possibility of our holding communication with the saints and angels in heaven, as Catholics are taught to believe they may. Across a space of such unknown vastness, it is alleged that the idea of transmitting a wish or a prayer is contrary to every principle of philosophy. Now, assuming, what indeed has never been proved, that the heaven of the blessed is as remote from our daily path as some maintain it to be, and without entering here into the abstract question as to whether the idea of space or of time is the older and simpler, some considerations are suggested by the study of modern scientific principles, which may throw light on the objection just staled, and may help us to ascertain its real worth.
It is evident that time and space may be made a measure of each other. The distance from one point in space to another may be expressed in so many units of time, say a minute, an hour, or a day, required to traverse the intervening distance at a given velocity. Hence, if velocity of motion [{380}] from point to point be represented by the simple formula of (Space/Time) we obtain two other formulas representing; time and space, respectively, in terms of each other.
Thus, if Velocity = Space/Time
Then, Time = Space/Velocity
and Space = Time X Velocity.
[Footnote 131]
[Footnote 131: For example, call Velocity 40 miles and hour, and Time 10 hours; then Space = 40 X 10 = 400 miles; or call Space 400 miles, Velocity being the same, then Time = 400/40 = 10 hours.]
There is a little instrument much valued by philosophical observers, but of no great intricacy in itself, which is at once an unerring measure of space and time; we mean a common pendulum oscillating seconds in a given level, say of London, at a given level, say of the sea, other conditions, as of the thermometer, etc., being the same. This instrument, beating seconds, is an invariable measure of length; in the latitude of London, for example, at the level of the sea, with thermometer at 62° Fahr., it is invariably 39.1393 inches long. And, conversely, provide such an instrument of the length just mentioned, and set it a-going; its oscillations will exactly measure out one second of time. Further, as a measure of length, it enables us to ascertain the weight of a cubic inch of water, in parts of a pound troy, whence the imperial standards of weight and capacity are derived. Hence a pendulum is a constant representative of space, in its length; and of time, in its oscillation. At any point on the surface of the globe, a rod of a certain given length will invariably, in similar circumstances, beat seconds; and a rod, beating seconds as it swings, will invariably measure a certain fixed length, according to the latitude. Why it does so, does not enter into our arguments now; it is enough that the fact is ascertained, and is one of the very commonest application to practise. Every good house-clock is evidence of it In the same town, for instance, the seconds' pendulums of all regularly-going clocks are of equal length to the minute fraction of an inch; and all pendulums, of the same length exactly, keep the same time exactly. In other words, space is made a measure of time, and time is a measure of space.
We said, just now, that space may be represented in terms of time, and time in those of space, the rate of Velocity being given. London is said to be ten hours from Edinburgh, when the transit is made at the rate of forty miles an hour. "As long as it would take to go to London," may be given as an expression equivalent to ten hours, at the same rate of motion. But vary that rate, and the terms used instantly represent very variable quantities. Ten hours from London, at the rate of a pedestrian travelling his four miles an hour, represent an insignificant distance of only forty miles; "as long as it would take to go to London" now expresses a period of a hundred hours, or more than four days. But take the wings of light, and instantly the distance supposed, if expressed in terms of time, dwindles to a minute portion of a second; even this is long, if you measure the space by the flash transmitted along the electric wire. Leaving the comparatively insignificant spaces on the surface of the globe for those vaster distances which divide planet from planet and from the sun, the time of 8 minutes 3.3 seconds, which the solar light takes to travel from its source to our globe may be taken as an expression of its distance from that luminary. Nay, there is a rate of velocity surpassing all these, bridging over the vast span of Neptune's orbit, for example, or the vaster diameter of a comet's path, in a unit of time too minute for the subtlest human instruments or calculations to appreciate. We mean the force or influence of gravitation, which, ever since the first moment when the sun and the planets were created, has been passing instantaneously from the centre of the solar system to every part, [{381}] even the most distant, of his wide empire, and back again from its furthest point to his centre.