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ON THE NATURE AND ADVANTAGES OF THE STUDY OF PHYSICS.

Being the Substance of an Introductory Lecture, delivered to the Class of Natural Philosophy, at Guy's Hospital; by W. M. HIGGINS, Esq., F. G. S., &c. &c.

PHYSICAL Science, in its widest application, embraces the investigation of matter in all its conditions and combinations. The entire material world comes under its cognizance. It not only considers the phenomena by which we are assured of material existence, but determines the properties of matter under all its forms, and the mutual influence which different species of matter, having various subordinate properties, exert upon each other. It embraces in its mighty grasp the laws of combination and form, the peculiarities of each individual element in itself, and in its union with others; enters the very laboratory of physical causes, and reveals the secret processes by which the universe itself is regulated.

But such a subject would be far too extensive for the mightiest human intellect, and we are compelled to form certain artificial divisions, that, by the united efforts of many, we may advance to some knowledge of the whole. The consideration of the material universe has, therefore, been divided among the natural historian, the chemist, and the experimental philosopher. To the first of these is appropriated the study of animals and vegetables, and the form and locality of mineral substances. Chemistry investigates all those phenomena which alter the composition of bodies, and endeavours to determine the nature of the elementary substances which enter into their formation. To the experimental philosopher is assigned the investigation of the laws of matter, and the nature and cause of all those phenomena in which it suffers change without altering any of the essential properties of its composition. But as these boundaries are artificial, they are often broken down, for the gradation from one to another is so perfect in nature, that it would be difficult to form such definitions as to prevent the student of one department from encroaching on the territories of the others.

But although we have thus divided physical science, and have appropriated only so small a part to the experimental philosopher, it is still necessary to arrange the objects of his pursuits, and hence we have the sciences of hydrodynamics, electricity, and others. One great advantage has resulted from this. Men of investigation have been able to devote themselves to particular subjects, and to pursue their concentrated inquiries at a time when knowledge was obtained with more difficulty than at present. We would not, however, insinuate that those who devote themselves to one science, are better fitted for discovery than those who have taken a wider view of nature. But in the infantine state of science, it was necessary, much more than at present, that there should be those who could give their undivided attention to the accumulation of facts, leaving their combination, and the deduction of general laws, to others, who had either more of the inspiration of nature, or had taken a more extensive view of physical causes. It is not the collectors of flowers, or of minerals, that can give the character of a country, and theorize on the problematic causes from which it originated, but the man who has traced the relations of its parts, and from an eminence surveyed its outline, and marked its features. And he will be best able to determine the immutable laws of nature, who, in the general pursuit of knowledge, has cultivated that spirit of generalization which can alone enable him to perceive the relative connexion of different phenomena.

From this view of philosophical pursuits, it must suggest itself as important to consider the process by which we are to be conducted to physical truths. The human mind has never arrived at any important discovery but by slow and progressive means. We have not a single instance of the discovery of a valuable fact by conjecture; and had this axiom been appreciated by the schoolmen of Greece, Rome, and the middle ages, modern philosophers would have had less to discover, and their labours would have been appreciated. Experiment, therefore, is the foundation of philosophy: for the want of it, men have established dogmas for causes; and by it, we have obtained the control of all material existence. It was long unknown to philosophers, why water rose in a pump. Without troubling themselves with an experiment, they assumed as a principle, that nature abhorred a vacuum; and therefore, as the atmospheric air was exhausted by suction, in the process of raising the piston, so it necessarily followed that the water must occupy its place. But it was accidentally discovered in the early part of the seventeenth

century, that water could not be raised in a pump, when the sucker was more than 32 feet from the surface of the water.

Unable to look beyond the dogma they had received from the ancient masters, they decided that nature did not abhor a vacuum for more than 32 feet! Torricelli, however, was not satisfied with the explanation; and a single experiment assured him that the phenomena were but the results of atmospheric pressure, and that the water did not rise more than 32 feet, because at that height it exactly balanced the pressure of a column of atmospheric air with a base of the same dimensions.

To prove the truth of this opinion, Torricelli made another experiment, which has produced scarcely less important results than the discovery of the principle.

Mercury being about thirteen and half times heavier than water, it is evident that a column of mercury about 30 inches long ought to counterpoise a column air of the same base. Experiment proved the truth of the supposition, and the barometer was the result of the investigations that followed. By the former experiment we ascertain a fact, which is the very conservative principle of nature. Without it, the vessels of both vegetable and animal bodies would be unable to hold their fluids which circulate through them, and the majority of liquids would assume the vapourous state. By the latter experiment we are put in possession of an instrument that is not only important as the prophet of atmo spheric changes, but is the invaluable companion of the traveller, as affording the best and readiest method of measuring heights.

Every science within the pale of experimental philosophy affords illustrations of the value of experiment; and it may be assumed as a principle, that it is the means by which we have ascertained every fact. But let it not be supposed that, in insisting on the high importance of experiment, we depreciate the value of mathematical studies. They are highly important and necessary to him who desires to investigate with minuteness any branch of physics; but they are not indispensable to an accurate knowledge of general principles, and we have abundant instances of successful experimenters who have been utterly ignorant of the mathematics. In the one case, we entirely trust to intellectual energy and the infallible power of numbers; in the other, to our senses, which though they offer a readier and more generally appreciable species of evidence, involve at the same time greater liabilities to error. The mixed method of investigation is, therefore, always to be preferred.

Let it further be remembered, that the fashion of the day is opposed to scientific research, and those who have passed their lives in such pursuits are too frequently treated with indifference and contempt. This has arisen in a great measure from the unpopular manner in which scientific truth has been explained. Men are not now to be attracted by mathematical erudition or startling propositions, but must have a plain reason, or actual experiment, for the statements which they are required to believe.

The great mass of mankind are unable to appreciate mathematical demonstration. Nor is it to be supposed that those from whose avocations it is remote, should be prepared to enter into its investigations. In such cases, the experimental style of teaching must be employed, and a direct appeal be made to the senses.

We must, then, in the study of nature, interrogate her by experiment; and if we can avail ourselves of the assistance of the sciences of quantity and number, we shall find them most useful auxiliaries in the study of the more complex phenomena. At all events, philosophy is not to be sought in the lap of luxury, or in the castles of indolence. She can only be acquired by patient investigation, and incessant exertion. It is, therefore, most important to the student, to ascertain whether the advantages which flow from a cultivation of experimental philosophy are adequate to the labour which will be experienced in acquiring it; and in endeavouring to determine this question, we shall consider, first, the personal, and then the public advantages which result from its cultivation.

It may here be necessary to remark, that when we enter upon the study of nature, we must renounce all preconceived opinions. Our senses are not always to be trusted to; their evidence frequently deceives us. Rash conclusions and opinions, deduced from an individual phenomenon, are generally erroneous. Because, for example, the heavenly bodies appeared to revolve round the earth, it was supposed to be the stable centre of the universe. But it was observed that, when a vessel or other vehicle is in rapid motion, and the eye of an observer situated in it, is fixed upon the objects in his path, they appear to be the moving bodies, and himself to be at rest. It would be difficult to determine, with these two observations, whether the earth or the heavenly bodies were in motion; that is, whether the observed motion was real or apparent. But the discovery of gravitation, and the immense distances of the stars, decide the question. Thus we gather from accumulated

phenomena, an incontrovertible proof that the earth is the revolving body, that we have been deceived by our senses, and that, in the investigation of physical causes, the mind must be waiting to receive the evidence of phenomena, whether they contradict or support our opinions.

I can conceive it possible that an individual should have so entirely devoted himself to other studies, as to be ignorant of every discovery of modern chemistry. Such an individual would consider water as an elementary substance, and, were we to speak of its decomposition, a feeling of incredulity would certainly rise in his mind. Now, let him proceed to the investigation, and with a few plates of copper and zinc, this apparently elementary body shall be decomposed, and the two gases of which it is constituted be collected in separate tubes. One of these, he is informed, is oxygen, which is a component part of air, and the supporter of combustion. The other, hydrogen, an explosive substance. When combined in their gaseous state, they form a most explosive compound; and, in proof of this fact, they are placed in the same tube, and ignited. But this last experiment has resolved them again into the liquid state, and drops of water are observed around the tube.

What must be the result of such information upon the mind of the classical scholar, when driven thus suddenly from an opinion that he had received upon the sanction of all the ancient philosophers. This, however, is but a solitary instance of what is hourly occurring, and we are thus admonished to renounce the influence of all preconceived opinions in philosophical inquiries, and to give every phenomenon its true estimate in the determination of a cause.

The greatest personal advantages arising from the cultivation of natural philosophy are, perhaps mental. There are men who would fain enrol themselves among_philosophers, to whom such a sentiment would seem highly enthusiastic and absurd. To what serviceable result can such a study be applied? is the question which they are incessantly asking; by which they mean to inquire, how much money can be made of it. On them the "auri sacra fames" has laid its hand, and forever forbids their acquisition of the advantages we describe. The best pleasures of life are but the flowers which beguile a laborious journey; and whatever may be the character of those we select, they are but few and occasional. Those who select them from the path of philosophy will find that they must pay their price, which is too often poverty and contempt. The epithets of worldly distinction are never conferred until the individual honours the title. The student of philosophy must, therefore, seek his remuneration from the influence which it will exert on his mind.

But, although the man who nobly devotes himself to scientific pursuits is thus oppressed by the indifference of the world, he finds numerous resources against the influence which, under ordinary circumstances, it exerts upon the character. Almost the first impression which he receives is an elevated estimate of the universal Governor. I do not assert, or believe, that it is equivalent to that which is obtained from the inspired writings; but it is the highest which can be obtained independent of revelation. In every feature of nature he traces the marks of a perfect mind, which governs and directs it; and in proportion to the minuteness of his examination, is his estimate of its wisdom. Having his mind thus deeply impressed with the universal and minute superintendence of a regulating Hand, he feels but little difficulty in committing himself to its government.

It has been asserted, that a deep investigation of nature tends to engender a spirit of scepticism. The habit which is acquired of tracing effects to their origin, leads them, it is imagined, to be satisfied with secondary causes, and to close their investigation where the noblest results are to be obtained. Thus they invest physical operations with the attributes of Deity, and resolve the origin of the wonders by which they are surrounded into fortuitous events, or invest the whole with immortality. We might fairly deny the assertion, by adducing numerous instances in which the deepest philosophical investigations have been united with the most exalted veneration of Deity; and it might be questioned whether those who have been known to deny a superintending power, have not obtained their opinions in some other school. But if we judge of the statement by the reason which is given, it may be unequivocally denied; for what can be more absurd than to state, that a habit of tracing from cause to effect prevents the mind from distinguishing between a primary from a secondary cause?

The study of nature will, therefore, lead the mind to value the presiding care of the universal Governor. A thousand individuals will pass over a beautifully varied country, and feel no other emotion than that arising from the influence of rugged scenery upon the

feelings. If they should be informed that it owes its present appearance to the violent convulsions which have upheaved the crust of the earth, they will either express their wonder or incredulity. But the geologist estimates the wisdom which designed the cause that led to such a result. Had the strata which compose the exterior of our earth remained in their horizontal position, the earth would have been one vast plain; no channel would have been provided for its waters, except those uncertain excavations which its passage formed; and the repositories of the metals and of coal, which are now exposed to view on the surface, would have been buried beyond the most curious research of man. But to him it is not a matter of surprise, it is but one of a series of facts, proving an intelligent design, and the choice of appropriate agents.

Air is a

This fact, however, is an instance of provision for the welfare of man, prior to his wants; an arrangement of causes, to produce a future state of things best suited to ensure human existence. There is scarcely a phenomenon in physics that does not show an arrangement of causes best suited to produce present results, and to harmonize with all other laws of nature. Take, for example, the properties of atmospheric air. union of two gases, oxygen and nitrogen, and is capable, in common with all fluids of its kind, of compression into a smaller space. The height of the atmosphere is about forty-five miles; and at its extreme height, the particles may be supposed to be in their free uncontrolled state. But as we descend towards the surface of the earth, the air becomes more and more dense, because it has to sustain the weight of that which is above it. The air has also the property of elasticity, and its elastic force increases in proportion to its density, so that in the same degree as it is subjected to pressure, is its elastic power or force of resistance increased. By this beautiful law, the condensation of air is prevented, and it is preserved to accomplish its important purposes in the economy of nature.

From the study of nature, then, we can hardly fail to gather ennobling views of the universal Governor-to deduce, that a knowledge of his character is essentially important, and that our happiness and safety is immediately under his control. It is difficult for those who have had the privilege of a revelation, to determine how far we may gather from nature the attributes of Deity, and his relation to man; but our only object is to shew, that the study of nature assists us in comprehending the statements it has made, and affords us, by an appeal to our senses, proofs of his superintending care.

Another personal advantage resulting from the cultivation of philosophy consists in raising our standard of happiness, by impressing us with a notion of the true dignity of the human mind. One original design in the creation of intelligence was to secure the appreciation of the natural world, and the praise of the Creator, as resulting from it. The investigation of nature still constitutes the best pursuit of man, and his nobility and power increases with his advance in knowledge.

The man who has advanced to some acquaintance with the phenomena of nature, and the causes from which they flow, feels himself raised above the great mass of mankind. He is conscious that the attributes of mind form the true and characteristic dignity of our species, and its health and energy the highest distinction of individuals. The laurels of the warrior are but the ensigns of our mortality; it is in the achievements of the philosopher that we realize our divine origin and our immortal destiny.

There is, however, another personal advantage arising from the investigation itself. Had philosophy no ulterior inducements to offer, the pleasures derived from the pursuit would be sufficient in themselves to allure. The mere love of knowledge, so deeply implanted in our nature, is, in itself, a reward for the toil of study. But the pleasure we derive from our pursuits is intimately associated with the kind of knowledge to be obtained. In the study of nature we are in pursuit of that which engaged the attention of the Supreme mind, and this thought makes us peculiarly conscious of the dignity of our pursuit.

When we have grasped a few of the general laws of nature, an additional pleasure is derived from a contemplation of their harmony. The scenes by which we may be surrounded, are no longer inadequate to our gratification, but in every change we are able to trace the combination of causes from which it proceeds. The mind, intent upon its purest gratification, is waiting for instruction, and seizes every phenomenon as an illustration of causes with which it is already acquainted, or deduces from it one with which it was before unacquainted. Thus, in the very pursuit of his inquiries, the philosopher finds his reward, independently of the advantages which are subsequently to be derived by society.

(To be continued.)