University of Virginia Library

1. CHAPTER I.
STATEMENT OF THE CASE—TESTIMONY OF THE
ATMOSPHERE.

THE time has been when the Christian Church was an active antagonist of physical science; when the whole hierarchy of Rome united to condemn its results and to resist its progress; when the immediate reward of great discoveries was obloquy and persecution. But all this has passed. The age of dogmatism has gone, and an age of general scepticism has succeeded. The power of traditional authority has given place to the power of ideas, and physical science, which before hardly dared to assert its birthright, and could even be forced to recant, on its knees, its demonstrated truths, has now become one of the rulers of society. By its rapid growth, by its conquests over brute matter, and by its wonderful revelations, it has deservedly gained the highest respect of man, while by multiplying and

diffusing the comforts of life it has become his acknowledged friend. Every effort is now made to further its progress. Its great discoveries win the applause of nations, and its fortunate students are remembered when the princes and nobles of the earth are forgotten.

All this is well. But unfortunately, elated by his success, the stripling has been at times proud and arrogant, usurping authority not his due. Forgetting his early faith, he has approached with irreverent thoughts the holy temple of our religion, and, not content to worship in the outer court, has dared to penetrate into the very Holy of Holies, and apply his material tests even to the vessels of the altar. No wonder that the Church should become alarmed, that many of her best men, holding fast to the sacred dogmas of our religion as the only sure anchor of their faith in this world, and their sole ground of hope for the next, should join in a general cry against the whole tendency of science and its results.

But this is a great mistake. Judging of the real character of physical science from the pretensions of a few, and not possessing the power or opportunity of investigating for themselves, these good men are unnecessarily alarmed: the phantom they fear is purely of their own creation, and, could they but know the whole truth, they themselves would see that to ignore the well-established results of science, and to denounce its legitimate tendency, is a policy as short-sighted as it is illiberal and unchristian.

Fortunately, such fearful souls constitute but a

small party in the Christian Church. There is a far nobler and more courageous faith than theirs,—a faith so strong in its convictions that it fears no criticism, however searching, and no scientific analysis, however rigorous it may be,—a faith which finds in the Bible, not a series of dead formulas, but a mass of living truth,—a faith which really believes that the God of nature is the God of grace, and that man was created in the image of this one and only God,—a faith which wells up from the depths of the soul, which speaks because it believes, which believes because it feels,—a faith whose sources are as hidden as those of the fountain, but whose reality is as living as the verdant landscape which the fountain waters.

It is the men with a faith like this who are the really brave Christians. They are not alarmed at the apparent contradictions between science and revelation. By the very imperfections of their own faculties, which they so keenly appreciate, they have been taught that mysteries exist; nay, they find in these very mysteries the strongest bulwarks of their faith; for they feel, with Robert Hall, that "a religion without its mysteries would be a temple without its God.'' They are fully assured that our minds were framed after the likeness of their Divine original, in order that we, creatures of the dust though we are, might nevertheless in our feeble measure comprehend God's workmanship and sympathize with his divine thoughts; and they reject as absurd the doctrine that man, thus created an intelligent and sympathizing observer of God's universe, should

have been permitted, in the legitimate exercise of the very powers which God has given him, to build up a connected system of science in direct contradiction to those higher and spiritual truths which the Father has been mercifully pleased to reveal to his sinning children through his prophets and his Son.

In the sight of this brave Christian faith there can be no essential contradiction between science and revelation. On the contrary, all nature appears radiant with the Divine Presence.

"The heavens declare the glory of God, and the firmament showeth his handiwork. Day unto day uttereth speech, and night unto night showeth knowledge. There is no speech nor language where their voice is not heard. Their line is gone out through all the earth, and their words to the end of the world.''

But although this glorious song of the Psalmist has been chanted through the ages as expressing the all but universal belief of thinking men, there has always existed at the same time a philosophy which interpreted the facts of nature in a very different way, and within the last few years this philosophy has become more than ever before dogmatic and aggressive. For the present we waive all discussion of the fundamental questions which materialism raises. With the increasing experience of life, we cling ever more and more fondly to the belief that the grand thoughts which the study of nature suggests to our mind are the manifestations of a Being who is not only to be venerated and feared

but also whom to be reverenced and loved. We believe that the instructions and suggestions of nature are the voices of an all-powerful Friend, who knows our capabilities and infirmities; who sympathizes in our joys and our sorrows, and who can be touched in our aspirations and our prayers; a Creator whose laws can not be broken, and whose behests must be obeyed; but also a Father who ever watches over his children, and who was in Christ reconciling the world unto himself.

We do not, of course, expect to reach such a faith as this through the study of nature alone. It comes not from the observation of external phenomena, but through the affections and aspirations of the soul, which finds in the Christian revelation that which answers to its needs and satisfies its cravings. Any system of natural theology like that of Paley which looks for its evidences solely to external phenomena, is of necessity defective and powerless. If nature could rise of her own self to spiritual things, there would have been no necessity for a revelation. Indeed, the attempt to establish a spiritual truth by the evidence of material phenomena, is, mutatis mutandis, but a repetition of the error of Aristotle and his school, who vainly sought to frame a system of natural philosophy independently of observation. The only satisfactory evidences of the truths of Christianity, independent of the historical record, are to be found in its adaptation to the spiritual needs of men, and it is such evidences of design alone that have persuaded the world.

Nevertheless, while we cannot expect to prove the fundamental principles of Christian theism by the evidences of material nature, it seems to us that an advantage may be gained by discussing material phenomena from the theistic point of view. The purely mechanical aspects of nature are now so prominently presented by ingenious and powerful writers that it may be a satisfaction to many thoughtful Christians if it can be shown that the same facts may be interpreted in a very different way, and that these facts are at least as consistent with the Christian theory of the origin of the universe as with the theory of the materialist. In this conclusion the Christian philosopher may securely rest, looking for the confirmation of his inherited faith to his own spiritual experience, in which alone convincing evidence can be found, according to the Master's promise: "If any man will do his will, he shall know of the doctrine, whether it be of God, or whether I speak of myself.''

The illustrations of the attributes of God, which may be drawn from the constitution of matter, are conveniently divided into two classes,—first, those which appear in the adaptation of various means to a particular end, and, second, those which are to be found in the unity of plan according to which the whole frame of nature has been constructed. The first class are exhibited by the properties of matter, the second by the so-called physical laws and forces.

In following out, then, the order which seems to be so obviously indicated by the nature of the case, I shall ask you, in the first place, to study with me

the physical condition of our atmosphere, and the properties of the various materials of which it consists; and I am sure we shall not fail to find in one and all abundant evidence of the wisdom, goodness, and power of God. Having thus made you acquainted with some of the more important scientific facts required for my argument, I shall next direct your attention to those grander demonstrations of God's wisdom and power which appear in the great laws and forces, by which the whole material universe is upheld, and lastly an examination of the relative limits of scientific and religious thought will form an appropriate termination for the course

The argument from special adaptations which lies at the basis of most works on natural theology is condensed by Dugald Stewart into two simple propositions. The one is, "that everything which begins to exist must have a cause;'' the other "that a combination of means conspiring to a particular end implies intelligence.'' To these might be added the two equally clear propositions stated by Dr. Reid: first, "that design may be traced from its effects;'' second, "that there are evidences of design in the universe.'' I do not at present intend to discuss the logical validity of this argument, or the general value of analogical reasoning which it implies. Such discussions belong particularly to the province of metaphysics, and I willingly leave them to abler hands. It will be my chief object in these lectures to bring to your notice a few of the numberless indications of adaptation in the materials of our atmosphere, assuming for the present that these

adaptations are evidences of design, and therefore evidences of the existence of a personal God, infinite in wisdom, absolute in power. When we have thus become acquainted with some of the facts on which the argument rests, we may then profitably consider the validity of the reasoning, at least so far as to weigh the objections which modern materialism has urged against it.

It must, however, be constantly borne in mind that the portion of the subject with which we are to deal should occupy only a very subordinate position in any comprehensive scheme of natural theology. We have already expressed the opinion that the only conclusive evidences of the truth of Christianity, apart from the historical record, are those based on its adaptation to the spiritual wants of men, and all other facts are secondary to this great central truth. But even when established on its broadest basis, I would not press the arguments of natural theology too far.

For myself, I believe that the facts of human nature themselves all tend to prove that a divine revelation is the only legitimate basis for a system of religion, and that an historical faith based on a supernatural revelation is the only religion possible for imperfect humanity. Indeed, I am led to think we find evidence of the goodness of our Heavenly Father in the very circumstance that the foundations of all knowledge have been laid in such obscurity that no unaided human intellect can wholly dispel the cloud which hides the Creator from our sight,—

This very obscurity humbles the pride of human learning, and raises its constant warning against that intellectual idolatry which would substitute its shallow philosophy for the simple truth as it is in Jesus. The Bible once received, science can furnish abundant illustrations of the attributes of the Being therein revealed; but even with all the illumination which has been the immediate or secondary result of Christianity, man is hopeless without its authority, and I would not give the slightest shadow of support to that irreverent presumption which, guided by what it calls the unaided light of nature, would construct a system of religion out of passions, intuitions, and I know not what absurdity.

But still it must be remembered that the Christian revelation does not prove the existence of God; on the contrary, it appeals to a belief in his being that already exists in the mind of man. The Bible opens with this assumption. The first line asserts that—

"In the beginning God created the heaven and the earth.''

And the Hebrew name of God, Jehovah (I am that I am), is itself a declaration of his self-existent being.

With all men a belief in some Almighty Power overshadowing their being grows up spontaneously in the heart, they know not how; but the educated and the intelligent seek further to find its logical grounds in the evidences of nature.

Here, then, is the first great office of natural theology. It furnishes the logical basis on which the whole scheme of revealed religion given us in the Bible rests.

I have no desire to over-estimate the importance of my subject. For myself, I believe, with Paley, and the other eminent writers of the same class, that the fundamental truths of our religion can be inferred from the constitution of the human mind and from the course of nature with as much certainty as analogical reasoning can ever give. But still I know that the evidence is not demonstrative and not likely to convince the sceptic; for in the last analysis it rests on certain assumptions which he will not admit. And it is in vain to urge that these assumptions are really intuitive truths and tacitly admitted by the whole human race; for he easily replies, that they are not intuitive to his mind.

Nevertheless, the evidences of God in nature— including, of course, the human soul—are the only proof we have or can have of his existence, and they are, therefore, the only logical basis of the Christian revelation. Nature and revelation are parts of one and the same system, and, however much our prejudices may obscure the fact, Christianity rests on natural religion, and cannot be logically defended if the authority of the last is denied.

But however great the value of natural theology, considered as the basis on which revelation rests, this is not its only or most important office. In the present age of the world, it confers a still more inestimable benefit on mankind by confirming, illustrating,

and enforcing the admitted truths of revelation.

If it be asked of what value are further illustrations of admitted truths, I answer, that there is an important class of nominal Christians who are more open to impressions from the study of nature than to direct appeals to the heart. It is true that the great mass of mankind must be Christianized, if at all, through the affections and by the hard discipline of sorrow; but there are some who, not yet tried in the fiery furnace of affliction, have first felt their Father's hand and recognized his love while contemplating his works. I do not say that persons so touched are already Christians, but I do say that the first step has been taken, and that is a great deal. It may require many years of sad experience and many a bitter pang of disappointment before they come to kneel humbly at their Saviour's feet; but, like the great Apostle, they will always look back to the time when the Divine presence first visibly shone before them as the turning period of their life.

While, therefore, I should be the first to condemn that hollow naturalism which would substitute a system of natural theism for the simple doctrines of the Bible, I must also deprecate that prejudice which prevents many clergymen, through fear of this tendency of the age, from availing themselves of the aid of science in enforcing the fundamental truths of our religion. I assure them they thus neglect a most important means of influence over educated and thinking men,—a means of influence always important, but never more so than in an age

which is marked by its cultivation of practical science, and in a country where so large a portion of the active energy of the community has taken this practical direction. The danger of our time is not so much a philosophical scepticism—as a practical materialism. The fear is, not that men should reason themselves into unbelief, but that, spending their whole lives in developing the powers of nature, they should practically worship the dead matter rather than the living God. If, however, we can make such persons feel that the material is but a form of the spiritual, and that in fact the spiritual is nowhere more manifest than in those very laws and forces which they so much idolize, we shall not change, it is true, the tendency of the age, but we shall ennoble and sanctify it. The whole material universe will become transfigured, and nature will no longer be seen as a wonderful mechanical application of blind forces, but as a living embodiment of the Eternal One. Nature-worship may continue, but it will have lost its idolatry; for it will be no longer the machine that is worshiped, but that same Living Spirit which spoke in tones of thunder from the clouds of Sinai and in accents of mercy at the baptism of Christ.

I know it is said that nature conceals rather than reveals God, and in a certain sense it is undoubtedly. true that He is hidden from us behind the veil of his works; but since it is permitted to man by the exercise of his intelligence to lift in part this veil, it is certainly the duty, as it should be the privilege, of the ministers of religion to show forth the unspeakable

glory which lies behind these material forms.

But why multiply arguments when we have the authority of the Great Teacher himself, who frequently appealed to nature to illustrate and enforce the divine truths which he came on earth to reveal? We have indeed the whole summary of Natural Theology in His simple words:

"Wherefore, if God so clothe the grass of the field, which to-day is, and to-morrow is cast into the oven, shall he not much more clothe you, O ye of little faith?''

With, then, such authority as this, let us not despise the beginnings because they are not the end, or undervalue the means by which many a noble soul has been led to the foot of the Cross.

Without seeking, therefore, to vindicate further the claims of my subject, I will at once enter upon the plan already proposed for this course of lectures, and will first ask your attention to the illustrations of the wisdom, goodness, and power of God, which may be discovered in the constitution of our atmosphere. In endeavoring to carry out this plan, I shall require all your indulgence and all your kind forbearance. From the very nature of the case, it will be necessary to start from first principles, and much of the way we are to travel together will be uninteresting and dull. If, however, the path shall lead us to the summit of that holy mountain from which we can gain a clearer vision of spiritual things, we shall soon forget the toil and difficulty of the ascent. We have no extravagant expectations of the result.

We do not hope to convince the sceptic, or to arouse the indifferent from their practical unbelief. Our only hope is—and this we entertain in all humility— that, by pointing out a few of the footprints of the Creator which lie thickly along our daily path, we may encourage some earnest student toiling forward on his journey of life. May God grant to us all the richest blessings of his grace; for though man may plant and water, He only giveth the increase.

The illustrations of the attributes of God presented to us by the atmosphere are especially manifest in those adaptations of properties by which it has been made to subserve the welfare and happiness of mankind, and this is to be expected, not only because these relations have been the most studied, and are, therefore, the best known, but also because the familiar phenomena through which our intelligences are connected with the external world, are the immediate objects of our observation and cognizance. Here, however, as always in the study of nature, we must be careful to avoid the error of considering man as the sole end of creation, and of interpreting all phenomena with reference to him alone. The material universe is the manifestation of one grand creative thought, as comprehensive in the diversity of the parts as it is grand in the unity of the whole. These parts have been so wondrously joined and skilfully wrought together, that each is linked with each, and one with all. In this divine economy nothing is wanting, nothing is superfluous, and what seems to our feeble vision least important is as essential to complete

the unity of the plan as our own glorious manhood:

Amidst all this wonderful variety in unity, man stands the culminating glory of the whole. Made in the image of his Creator, and but "a little lower than the angels,'' he has been intrusted with dominion and power over all the brute matter which surrounds him. Through the long ages of geological history the earth was preparing for his dwelling, and in the earliest forms of animal life his coming was prefigured and foretold. It will be natural, therefore, to consider the adaptations of the atmosphere with special reference to him; and this we may do legitimately, without losing sight of the grand idea which underlies the whole, and of which man is only the nobler part.

The atmosphere is a vast ocean of aeriform matter, enveloping the earth like a mantle, and rising to the height of many miles above our heads, but constantly diminishing in density as the elevation increases. At the height of about three miles and a half (3.43) the density is only one-half as great as at the level of the sea; and at the height of forty miles it is less than in the exhausted receiver of the best air-pumps. How much higher than this the atmosphere extends, it is impossible to determine with accuracy. In this ocean of air all bodies on the surface of the globe are immersed. It is so subtle

that it penetrates into the minute pores of matter, and fills the cavities of all organized being. It is the medium in which all vital processes both of plants and animals take place, and in which all human activity has its seat. Let us see now with what wisdom its properties have been adapted to the important ends which it is appointed to subserve.

Consider, in the first place, the physical state of the atmosphere, its very aeriform condition. This air is as truly matter as the solid planks on which we are treading, or the granite rocks on which this building rests. It is far less dense, it is true, but then it has all the essential properties of matter. It fills space. It resists with an ever-increasing force all attempts to condense it; and, moreover, it has weight. But how different in condition from the solid rock!—so different that to the uneducated it hardly seems material; and in our common language we speak of a space which is filled only with air as empty. Its particles are endowed with such perfect freedom of motion, and yield so readily to the slightest pressure, that we move through it without feeling its presence. It is firm enough to support the wings of the lark as he mounts the sky, and yet so yielding as not to detain the tiniest insect in its rapid flight.

The physical condition of the atmosphere will still further excite our admiration, when we consider the wonderful play of forces by which it is upheld. It may not be known to you all that upon this mass of air, outwardly so calm and passive, there are constantly

acting two mighty forces,—the force of gravitation and the force of heat. In virtue of the force of heat the particles of the atmosphere mutually repel each other, and the whole mass, like a bent spring, tends to break from its confinement and to expand into the surrounding space; but this it cannot do, for by the power of gravitation it is held with a firm grasp to the surface of the globe. Were this grasp for a moment relaxed, the atmosphere would dash off with explosive violence and be lost in the immensity which surrounds us. How great the force is which is required to restrain the expansive tendency of the atmosphere few persons have an adequate conception, because the two opposing forces are so perfectly balanced that we are obliged to call in the aid of experiment in order to render their effects evident. So true is this, that the world never even dreamed of their existence until within two hundred years, and the story of the discovery is one of the most remarkable in the history of inductive philosophy. This story is well known; but as it is short, and teaches us an important truth, you will pardon its repetition.

Every one who has seen a common pump is familiar with the fact that it is the pressure of the air which causes the water to rise in the suction-pipe, and this suction is one manifestation of that force by which the atmosphere is held so firmly to the surface of the globe. The pump, however, was used long before the discovery of the pressure of the atmosphere, and its action was explained by a principle which seemed perfectly satisfactory then, but

which sounds strangely enough to modern ears. The principle appears first to have originated with the Aristotelians, and was expressed in the phrase, "Nature abhors a vacuum.'' These ancient philosophers noticed that space was always filled with some material substance, and that the moment a solid body was removed air or water always rushed in to fill the empty space. Hence they concluded that it was a universal law of nature that space could not exist unoccupied by matter, and the phrase just quoted was merely their figurative expression of this philosophical idea. When, for example, the piston of a common pump was drawn up, the rise of the water was explained by declaring, that, as from the nature of things a vacuum could not exist, the water necessarily filled the space deserted by the piston.

This physical dogma served the purpose of natural philosophy for two thousand years, and it was not until the seventeenth century that men discovered any limit to nature's abhorrence of a vacuum. Near the middle of that century some engineers were employed by the Duke of Tuscany to sink a well in the neighborhood of Florence to an unusual depth. They finished their work, but on adjusting the pump they found to their surprise that it would not work. With all their efforts the water would rise only a little more than thirty feet, and by no ingenuity or skill could they raise it an inch higher. More disgusted with nature than nature was with the vacuum in their pump, they applied to Galileo, then an old man, living in his villa on the brow of Fiesole.

He could not aid them, but he is said to have replied, half in jest, half in earnest, that nature did not abhor a vacuum above thirty feet. Had this incident occurred earlier in his career, Galileo would undoubtedly have added to the other jewels of his crown a brighter gem than all, but now the vigor of his manhood was spent; he had done his work, and, worn out by the persecution of a bigoted priesthood, he was peacefully resting from his life's labor, and calmly awaiting the close.

But the key which the incident had furnished was not lost. It passed into able hands, and it was the fortune of Torricelli, Galileo's best pupil, to unlock the secret. This young Italian philosopher, whose clear, intellect had been trained in the mechanical philosophy of his great master, saw at once that a column of water thirty-three feet high, and no higher, could not be sustained in a cylindrical tube by a mere metaphysical abstraction.

This effect, he said, must be the result of some mechanical force equivalent to the weight of the mass of water sustained. It was not difficult to prove the correctness of this reasoning, for it was evident that if a column of water was sustained at the height of thirty-three feet in the suction-pipe of a pump by a constant force, the same force could only sustain a column of a heavier liquid at a proportionally less height. So Torricelli tried mercury, a liquid thirteen and a half times heavier than water, and the result was as he had anticipated. The force which raised the column of water thirty-three feet could only raise a column of mercury to the height

of thirty inches, which is thirteen and a half times less than thirty three feet. Torricelli did not, however, make this experiment with a pump, but with an apparatus of his own, much simpler, and equally effective.

He took a long glass tube, open at one end, filled it with mercury, and, having closed the opening with his thumb, inverted the tube, and plunged the open end in a basin of mercury; on removing his thumb, the mercury, instead of remaining in the tube, and thus satisfying nature's abhorrence of a vacuum, fell, as he expected, and, after a few oscillations, came to rest at a height of about thirty inches above the level of the mercury in the basin. The correctness of his induction having been thus verified, Torricelli at once concluded that it must be the pressure of the air which sustained both the water in the pump and the mercury in his tube.

This experiment excited a great sensation in Europe; but, as might naturally have been expected, the old physical dogma was not easily laid aside, and Torricelli did not live to see his opinion generally received. It was left to the celebrated Blaise Pascal to convince the world that Torricelli was right, and this he did by one of those master-strokes of genius which at once silence controversy.

"If,'' said Pascal, "it be really the weight of the atmosphere under which we live that supports the column of mercury in Torricelli's tube, we shall find, by transporting this tube upward in the atmosphere, that in proportion as it leaves below it more and more of the air, and has consequently less and

less above it, there will be a less column sustained in the tube, inasmuch as the weight of the air above the tube, which is declared by Torricelli to be the force which sustains it, will be diminished by the increased elevation of the tube.''

Accordingly Pascal carried the tube to the top of a church-steeple in Paris, and observed that the mercury fell slightly; but not satisfied with this result, he wrote to his brother-in-law, who lived near the high mountain of Puy de Dôme, in Auvergne, to make the experiment there, where the result would be more decisive.

"You see,'' he writes, "that if it happens that the height of the mercury at the top of the hill be less than at the bottom (which I have many reasons to believe, though all those who have thought about it are of a different opinion), it will follow that the weight and pressure of the air are the sole cause of this suspension, and not the horror of a vacuum; since it is very certain that there is more air to weigh on it at the bottom than at the top; while we cannot say that nature abhors a vacuum at the foot of a mountain more than on its summit.'' M. Perrier, Pascal's correspondent, made the observation as he desired, and found a difference of about three inches, "which,'' as he replies, "ravished us with admiration and astonishment.''

Thus it was that man first learned to recognize the existence of that power, which retains the atmosphere on the surface of the globe, and the history of the discovery should humble our intellectual pride and teach us to hold our knowledge with reverence

and humility. This old scientific dogma of the seventeenth century never fails to excite a smile, and we are inclined to wonder how man could ever have believed what now appears so absurd; but if, like an antiquary, we imbue our minds with the spirit of that age, it will be seen, not only that the dogma was not essentially absurd, but also that the philosophical idea, clothed in those quaint terms, appeared to the scientific men of the period as truly a legitimate induction from observed facts as the law of gravitation seems to us. And the induction was legitimate; but since the known facts did not cover the whole ground, they gave only a very partial truth. The Grand Duke's pump was the first failing case, and proved, not that the old principle was absolutely false, but only that its application was very limited.

Thanks to Galileo, Torricelli, Pascal, and Newton—noble line of genius—nature's abhorrence of a vacuum gave place to the law of gravitation, and two centuries of unparalleled scientific activity have only served to confirm the truth, and extend the domain of Newton's grand generalization; but even after this signal triumph, who now feels fully assured that the law of gravitation may not find its failing case? and when, two centuries hence, the future historian comes to write the history of inductive philosophy, who can feel certain that Aristotle's dogma and Newton's law may not both be condescendingly noticed among the partial truths which served the purposes of science in its infancy and childhood?

Let me not be understood to imply a belief that man cannot attain to any absolute scientific truth, for I believe that he can, and I feel that every great generalization brings him a step nearer to the promised goal; but I wish here at the outset most strongly to impress the distinction between the undoubted facts of science, and the laws and principles which have grown up around them, and by which they have been embodied in our systems of philosophy,—the distinction, in a word, between the observed phenomena of nature, and man's interpretation of the phenomena.

This distinction, so obvious when stated, is too often forgotten, and is necessarily overlooked in our scientific text-books. It is the sole aim of these elementary treatises to teach the present state of knowledge, and they would fail in their object if they attempted by a critical analysis to separate the phenomena from the laws or systems by which alone the facts of nature are correlated and rendered intelligible. But although while studying science itself, we may for the time waive the distinction between fact and theory, the moment we come to compare the results of science with the eternal verities of religion, the distinction here enforced becomes of paramount importance, and it must be our chief aim to separate that which is absolute and eternal truth from that which, even in its highest development, is the result of human thought, and, like all things human, subject to limitations and liable to change.

Had this distinction been always borne in mind, the controversies between the philosophers and the

churchmen would have been less bitter and more fruitful in truth; the philosophers would have been willing to waive their theories, and the churchmen would have been led to respect the results of science, and conform their theology to the indisputable truths which God has been pleased to reveal through nature no less plainly than in his written word; and if the trite anecdote of Galileo and the pump-makers serve to impress the distinction on our minds, this digression will not have been made in vain.

You must all have recognized in Torricelli's tube our modern barometer. By means of this well-known instrument we can readily estimate the pressure of the atmosphere, and determine the amount in our human standards of measurement. It can be readily proved that the pressure of the atmosphere is about fifteen pounds on every square inch of the earth's surface, and if, starting from this well-known fact, you calculate the amount of pressure on any extended surface, you will be astonished at the result. For example, the pressure exerted by the atmosphere on the area on which this building stands is much greater than the whole weight of the building itself. The pressure on a man of ordinary stature is about sixteen tons; that on one square mile of surface is equal to over twenty-six million tons.

How great, then, must be the pressure on the whole surface of the globe, or, what is the same thing, how great is the intensity of that ever-acting power, which holds the atmosphere in its appointed place! It would not be difficult to calculate the

amount and to express it in numbers; but these numbers would convey to you no definite idea, for our minds are incapable of forming an adequate conception of such immensity. The attempt to grasp it only exposes our weakness, and yet this force, immense as it is, is so delicately balanced by the sweet influences of the sunbeam, that it does not so much as shake the aspen-leaf or break the gossamer. If we believe no more than this, that the world was once created by God, what must be the power and wisdom of a being who could appoint these mighty forces and adjust them with such perfect precision! But if we also believe that these forces are direct emanations of Divine Power,—that it is God himself who with his own right hand holds the atmosphere in its place, and appoints its bounds,—then all nature assumes a more glorious aspect, and we feel that we are indeed surrounded by the Divine Presence. Yet this force, which we find so far beyond our powers of conception, is but a secondary phase of that immeasurably greater power which brings forth Mazzaroth in his season, and guides Arcturus with his sons. How futile all attempts to measure Divine power! We select some one of the feeble forces acting around us, and succeed in reducing its value to our human standards of comparison, and expressing this value in numbers; but the numbers, when obtained, are beyond our grasp, and we find that we have merely mounted to a little higher platform, from which we discover numberless other forces immeasurably greater than the first. Something, however, has been gained. We have attained to the idea of the infinite; and to thoroughly apprehend the existence of the infinite, is to take the first step toward recognizing the existence of a God.

I know it will be said that man cannot comprehend the infinite, and if by this statement it is only meant to affirm the declaration of the Bible, that man cannot "find out the Almighty unto perfection,'' not even the most visionary dreamer would question the position. But there is a class of philosophers at the present day who think to enforce the authority of revelation by maintaining the doctrine that man can know absolutely nothing of the infinite,—nothing more than he now knows of the facts or principles of science to be hereafter discovered; that, indeed, the very term infinite implies a negation of all cognizable qualities.

To me, this position seems fatal to the very cause it is intended to defend, and surrenders all the approaches of the citadel to the infidel. For if there is in man no possibility of apprehending the infinite, even to the smallest degree, I can see nothing to which revelation can appeal. He has then no power to distinguish between the Divine and the human.

But it is not so. Revelation implies, and all experience shows, that man can recognize the presence of the infinite by attributes as clear and unmistakable as those which mark the presence of the finite matter around him. He may not be able to comprehend a single attribute of the infinite in its essence; but as the mathematician, dealing with infinitesimal quantities, which he cannot fully understand,

arrives at truths of the material world with all the certainty of demonstration, so the mental philosopher may attain to moral truths in regard to the Infinite Being, although the very terms he employs may be veiled in impenetrable mystery.

And what is the true human conception of the infinite? It is not merely something which we feel to be very great indeed, but it is something which we feel surpasses our utmost conceptions of the great,—something which, let us account it as great as we please, yet, wherever the inability of our mental power fixes the limit of our conception, will still be felt to be greater than the greatest. We cannot gaze into the heavens without awe; we cannot examine the wonders of the dew-drop without reverence; we cannot look into our own souls without trembling. It is the same invisible Presence everywhere, and however long false philosophy may conceal the vision, or material cares and pleasures blind the senses, when man once recognizes its existence he instinctively worships and adores.

The far-reaching relations of the adaptations we are now studying become evident when we consider that the density of the atmosphere is one of the conditions of organic life on the surface of the globe. By density is meant, I need not state, the quantity of matter which the atmosphere contains in a given volume; for example, in a cubic yard. This quantity is capable of exact measurement, and although to a certain extent variable, it is constant in the same place, under the same conditions of temperature and pressure.

In this latitude, at the level of the sea, one cubic yard of the atmosphere, when dry and under the normal conditions of temperature and pressure, contains about two pounds of air, and this weight is the measure of its density. Now we find that the organization of plants and animals, including man, has been adjusted to the density of the air, and illustrations of this adaptation will be met with as we proceed. But accepting the fact for the present as universally conceded, let us consider the conditions on which this adaptation of the air to our physical organization rests.

The density of the atmosphere may be said to depend upon four conditions: first, on the inherent nature of the substance which we call air itself; secondly, on the intensity of gravity; thirdly, on the total quantity of air on the globe; and, lastly, on the temperature. The influence of the first condition is not understood, but that of the last three we can readily trace. If the intensity of the force of gravity at the surface of the earth were to change, other circumstances remaining the same, the density of the atmosphere would change in the same proportion. Thus, for example, if the intensity of gravity on the earth were as great as it is on the surface of the sun, the density of the atmosphere would be twenty-eight times as great as at present; or if this intensity were reduced to that which exists on the surface of the moon, the density would be diminished to one-sixth of the existing density.

But, assuming that the intensity of the force of gravity on the surface of the earth remained constant,

precisely the same effect would result from any variation in the total quantity of the atmosphere. Were the whole amount of air on the earth increased or diminished, the density of the atmosphere at its surface would also be increased or diminished in the same proportion. Still further, assuming that, while the intensity of gravity and the mass of the atmosphere remained fixed, the temperature were changed, then also the density of the atmosphere would vary, and by a quantity which can be easily determined. By accurate experiments it has been ascertained that an elevation of temperature equivalent to about five hundred degrees of our Fahrenheit thermometer would reduce the density to one-half; and, on the other hand, that a reduction of temperature would increase the density in the same proportion.

Consider next what these relations imply. Reflect that the intensity of the force of gravity depends upon the mass of the earth. Remember that the mean temperature depends upon the distance of the earth from the sun, and you will see that not only the actual size of the earth, but also its distance from the sun, and the quantity of air on its surface, were all necessary conditions in order that the atmosphere should have its present density, and thus become the fit abode for the actual families of organic beings. If any one of these conditions had been different, the same result would not have been attained, and man, as he exists, could not have lived on this globe.

It must then have been He "who hath meted out

heaven with the span, and comprehended the dust of the earth in a measure, and weighed the mountains in scales, and the hills in a balance,'' who "formed man of the dust of the ground, and breathed into his nostrils the breath of life.''

The unity of the design implies the oneness of the designer, and although the adaptations just considered may not exclude every possible atheistic theory of cosmogony, yet they show conclusively that, if there is design anywhere, there is design everywhere; if there is design in the least, there is design also in the greatest, and design in the atom may thus confirm the evidence of design in man.