JOHN TYNDAL L. [Professor Tyndall is an instance of native | and apt illustration. Indeed, he is one of the genius and energy raising themselves to a pioneers in the new era, in which a polished lofty reputation in spite of early difficulties, style has been found quite compatible with and by nought but worthy means. the revelation of physical truths. His pub on purely scientific subjects; but occasional visits to the Continent and explorations among the Alps have led to the production of pleasant volumes, in which the scientist brings into striking and sometimes amusing combination the dreamy eye of the lover of the picturesque, and the keen eye of the philosopher in search of explanations of physical phenomena.] SCIENTIFIC LIMIT OF THE IMAGINATION. (FROM ADDRESS TO BRITISH ASSOCIATION.1) John Tyndall was born in 1820 at Leighlin-lished works are numerous. Most of them are Bridge, Carlow. His parents were poor; but, with that zeal for education which is one of the best characteristics of the Irish people, they managed to have their son taught well; and he early acquired a sound knowledge of mathematics. His first employments were not of a particularly philosophic character, for he had to be content with the post of a "civil assistant" of the Ordnance Survey in his native district, and with employment in railway engineering operations in connection with a Manchester firm. In 1847 came what was, probably, much more congenial employment, when he received an appointment as a teacher in Queenwood College, Hampshire. Here he formed a friendship which was destined to deeply influence his life. The chemist of the college was Mr. (now Dr.) Frankland, and with him Tyndall began that career of physical investigation in which he has since gained such a fame. In company with his friend he went abroad and prosecuted for some time the study of chemical and other phenomena. His discoveries had been noted, and he received the fellowship of the Royal Society. In 1853 he was elected professor of natural philosophy in the Royal Institution, and was successor of Michael Faraday as superintendent. It is not our duty to speak in detail of his scientific achievements. We must content ourselves with saying that he has received those honours which are conferred on those alone who have reached the highest position in the scientific world. He has been President of the British Association, has been made an LL.D. of Cambridge and of Edinburgh, a D.C.L. of Oxford, and held office in 1877 as President of the Birmingham and Midland Institute. In 1872 he went on a lecturing tour in the United States, and the proceeds he devoted to the encouragement of original research. Professor Tyndall is best known to the general public as a lecturer. He shares with his friend, Professor Huxley, a singular power of making the dark ways of science light to the ordinary understanding by a style of wonderful clearness, and brightened with humour If you look at the face of a watch you see the hour and minute hands, and possibly also a second-hand, moving over the graduated dial. Why do these hands move? and why are their relative motions such as they are observed to be? These questions cannot be answered without opening the watch, mastering its various parts, and ascertaining their relationship to each other. When this is done we find that the observed motion of the hands follows of necessity from the inner mechanism of the watch when acted upon by the force invested in the spring. The motion of the hands may be called a phenomenon of art, but the case is similar with the phenomena of nature. These also have their inner mechanism, and their store of force to set that mechanism going. The ultimate problem of physical science is to reveal this mechanism, to discern this store, and to show that from the combined action of both the phenomena of which they constitute the basis must of necessity flow. I thought that an attempt to give you even a brief and sketchy illustration of the manner in which scientific thinkers regard this problem would not be uninteresting to you on the present occasion; more especially as it will give me occasion to say a word or two on the tendencies and limits of modern science; to point out the region which men of science 1 By permission of the author. claim as their own, and where it is mere waste of time to oppose their advance, and also to define, if possible, the bourne between this and that other region to which the questionings and yearnings of the scientific intellect are directed in vain. There have been writers who affirmed that the pyramids of Egypt were the productions of nature; and in his early youth Alexander von Humboldt wrote a learned essay with the express object of refuting this notion. We now regard the pyramids as the work of men's hands, aided probably by machinery of which no record remains. We picture to ourselves the swarming workers toiling at those vast erections, lifting the inert stones, and, guided by the volition, the skill, and possibly at times by the whip of the architect, placing them in their proper positions. The blocks in this case were moved and posited by a power external to themselves, and the final form of the pyramid expressed the thought of its human builder. Let us pass from this illustration of constructive power to another of a different kind. When a solution of common salt is slowly evaporated, the water which holds the salt in solution disappears, but the salt itself remains behind. At a certain stage of concentration the salt can no longer retain the liquid form; its particles, or molecules, as they are called, begin to deposit themselves as minute solids, so minute, indeed, as to defy all microscopic power. As evaporation continues solidification goes on, and we finally obtain, through the clustering together of innumerable molecules, a finite crystalline mass of a definite form. What is this form? It sometimes seems a mimicry of the architecture of Egypt. We have little pyramids built by the salt, terrace above terrace from base to apex, forming a series of steps resembling those up which the Egyptian traveller is dragged by his guides. The human mind is as little disposed to look unquestioning at these pyramidal salt-crystals as to look at the pyramids of Egypt without inquiring whence they came. How, then, are those salt-pyramids built up? Guided by analogy, you may, if you like, suppose that, swarming among the constituent molecules of the salt there is an invisible population, guided and coerced by some invisible master, and placing the atomic blocks in their positions. This, however, is not the scientific idea, nor do I think your good sense will accept it as a likely one. The scientific idea is that the molecules act upon each other with out the intervention of slave labour; that they attract each other and repel each other at certain definite points, or poles, and in certain definite directions; and that the pyramidal form is the result of this play of attraction and repulsion. While, then, the blocks of Egypt were laid down by a power external to themselves, these molecular blocks of salt are self-posited, being fixed in their places by the forces with which they act upon each other. I take common salt as an illustration because it is so familiar to us all; but any other crystalline substance would answer my purpose equally well. Everywhere, in fact, throughout inorganic nature, we have this formative power, as Fichte would call it-this structural energy ready to come into play, and build the ultimate particles of matter into definite shapes. The ice of our winters and of our polar regions is its handiwork, and so equally are the quartz, felspar, and mica of our rocks. Our chalk-beds are for the most part composed of minute shells, which are also the product of structural energy; but behind the shell, as a whole, lies a more remote and subtle formative act. These shells are built up of little crystals of calc-spar, and to form these crystals the structural force had to deal with the intangible molecules of carbonate of lime. This tendency on the part of matter to organize itself, to grow into shape, to assume definite forms in obedience to the definite action of force, is, as I have said, allpervading. It is in the ground on which you tread, in the water you drink, in the air you breathe. Incipient life, as it were, manifests itself throughout the whole of what we call inorganic nature. The forms of the minerals resulting from this play of polar forces are various, and exhibit different degrees of complexity. Men of science avail themselves of all possible means of exploring their molecular architecture. For this purpose they employ in turn as agents of exploration, light, heat, magnetism, electricity, and sound. Polarized light is especially useful and powerful here. A beam of such light, when sent in among the molecules of a crystal, is acted on by them, and from this action we infer with more or less of clearness the manner in which the molecules are arranged. That differences, for example, exist between the inner structure of rock-salt and crystallized sugar or sugar-candy, is thus strikingly revealed. These differences may be made to display themselves in chromatic phenomena of great splendour, the play of molecular force being so regulated as to remove some of the coloured constituents of white light, and to leave others with increased intensity behind. And now let us pass from what we are accustomed to regard as a dead mineral to a living grain of corn. When it is examined by polarized light, chromatic phenomena similar to those noticed in crystals are observed. And why? Because the architecture of the grain resembles the architecture of the crystal. In the grain also the molecules are set in definite positions, and in accordance with their arrangement they act upon the light. But what has built together the molecules of the corn? I have already said regarding crystalline architecture that you may, if you please, consider the atoms and molecules to be placed in position by a power external to themselves. The same hypothesis is open to you now. But if in the case of crystals you have rejected this notion of an external architect, I think you are bound to reject it now, and to conclude that the molecules of the corn are self-posited by the forces with which they act upon each other. It would be poor philosophy to invoke an external agent in one case and to reject it in the other. Instead of cutting our grain of corn into slices and subjecting it to the action of polarized light, let us place it in the earth and subject it to a certain degree of warmth. In other words, let the molecules, both of the corn and of the surrounding earth, be kept in that state of agitation which we call warmth. Under these circumstances the grain and the substances which surround it interact, and a definite molecular architecture is the result. A bud is formed; this bud reaches the surface, where it is exposed to the sun's rays, which are also to be regarded as a kind of vibratory motion. And as the motion of common heat with which the grain and the substances surrounding it were first endowed, enabled the grain and these substances to exercise their attractions and repulsions, and thus to coalesce in definite forms, so the specific motion of the sun's rays now enables the green bud to feed upon the carbonic acid and the aqueous vapour of the air. The bud appropriates those constituents of both for which it has an elective attraction, and permits the other constituent to resume its place in the air. Thus the architecture is carried on. Forces are active at the root, forces are active in the blade, the matter of the earth and the matter of the atmosphere are drawn towards both, and the plant augments in size. We have in succession the bud, the stalk, the ear, the full corn in the ear; the cycle of molecular action being completed by the production of grains similar to that with which the process began. Now there is nothing in this process which necessarily eludes the conceptive or imagining power of the purely human mind. An intellect the same in kind as our own would, if only sufficiently expanded, be able to follow the whole process from beginning to end. It would see every molecule placed in its position by the specific attractions and repulsions exerted between it and other molecules, the whole process and its consummation being an instance of the play of molecular force. Given the grain and its environment, the purely human intellect might, if sufficiently expanded, trace out à priori every step of the process of growth, and, by the application of purely mechanical principles, demonstrate that the cycle must end, as it is seen to end, in the reproduction of forms like that with which it began. A similar necessity rules here to that which rules the planets in their circuits round the sun. You will notice that I am stating my truth strongly. . . But I must go still further, and affirm that, in the eye of science, the animal body is just as much the product of molecular force as the stalk and ear of corn, or as the crystal of salt or sugar. Many of the parts of the body are obviously mechanical. Take the human heart, for example, with its system of valves, or take the exquisite mechanism of the eye or hand. Animal heat, moreover, is the same in kind as the heat of a fire, being produced by the same chemical process. Animal motion, too, is as directly derived from the food of the animal, as the motion of Trevethyck's walking engine from the fuel in its furnace. As regards matter, the animal body creates nothing; as regards force, it creates nothing. Which of you by taking thought can add one cubit to his stature? All that has been said, then, regarding the plant may be restated with regard to the animal. Every particle that enters into the composition of a muscle, a nerve, or a bone, has been placed in its position by molecular force. And unless the existence of law in these matters be denied, and the element of caprice introduced, we must conclude that, given the relation of any molecule of the body to its environment, its position in the body might be determined mathematically. Our difficulty is not with the quality of the problem, but with its complexity; and this difficulty might be met by the simple expansion of the faculties which we now possess. Given this expansion, with the necessary molecular data, and the chick might be deduced as rigorously and as logically from the egg as the existence of Neptune was deduced from the disturbances of Uranus, or as conical refraction was deduced from the undulatory theory of light. sciousness is unthinkable. Granted that a definite thought, and a definite molecular action in the brain occur simultaneously; we do not possess the intellectual organ, nor apparently any rudiment of the organ, which would enable us to pass, by a process of reasoning, from the one to the other. They appear together, but we do not know why. Were our minds and senses so expanded, strengthened, and illuminated as to enable us to see and feel the very molecules of the brain; were we capable of following all their motions, all their groupings, all their electric discharges, if such there be; and were we intimately acquainted with the corresponding states of thought and feeling, we should be as far as ever from the solution of the problem, "How are these physical processes connected with the facts of consciousness?" The chasm between the two classes of phenomena would still remain intellectually impassable. Let the consciousness of love, for example, be associated with a right-handed spiral motion of the molecules of the brain, and the consciousness of hate with a left-handed spiral motion. We should then know when we love that the motion is in one direction, and when we hate that the motion is in the other; but the "WHY?" would remain as unanswerable as before. You see I am not mincing matters, but avowing nakedly what many scientific thinkers more or less distinctly believe. The formation of a crystal, a plant, or an animal, is in their eyes a purely mechanical problem, which differs from the problems of ordinary mechanics in the smallness of the masses and the complexity of the processes involved. Here you have one half of our dual truth; let us now glance at the other half. Associated with this wonderful mechanism of the animal body we have phenomena no less certain than those of physics, but between which and the mechanism we discern no necessary connection. A man, for example, can say I feel, I think, I love; but how does consciousness infuse itself into the problem? The human brain is said to be the organ of thought and feeling; when we are hurt the brain feels it, when we ponder it is the brain that thinks, when our passions or affections are excited it is through the instrumentality of the brain. Let us endeavour to be a little more precise here. I hardly imagine there exists a profound scientific thinker, who has reflected upon the subject, unwilling to admit the extreme probability of the hypothesis, that for every fact of consciousness, whether in the domain of sense, of thought, or of emotion, a certain definite molecular condition is set up in the brain; who does not hold this relation of physics to consciousness to be invariable, so that, given the state of the brain, the cor-yond this position. I do not think he is entitled responding thought or feeling might be inferred; or given the thought or feeling, the corresponding state of the brain might be inferred. In affirming that the growth of the body is mechanical, and that thought, as exercised by us, has its correlative in the physics of the brain, I think the position of the "Materialist” is stated, as far as that position is a tenable one. I think the materialist will be able finally to maintain this position against all attacks; but I do not think, in the present condition of the human mind, that he can pass be to say that his molecular groupings and his molecular motions explain everything. In reality they explain nothing. The utmost he can affirm is the association of two classes of phenoBut how inferred? It is at bottom not a mena, of whose real bond of union he is in absocase of logical inference at all, but of empiri- lute ignorance. The problem of the connection cal association. You may reply that many of of body and soul is as insoluble in its modern the inferences of science are of this character; form as it was in the prescientific ages. Phosthe inference, for example, that an electric phorus is known to enter into the composition current of a given direction will deflect a of the human brain, and a trenchant German magnetic needle in a definite way; but the writer has exclaimed, "Ohne Phosphor, kein cases differ in this, that the passage from the Gedanke." That may or may not be the current to the needle, if not demonstrable, is case; but even if we knew it to be the case; thinkable, and that we entertain no doubt as the knowledge would not lighten our darkto the final mechanical solution of the prob-ness. On both sides of the zone here assigned lem. But the passage from the physics of to the materialist he is equally helpless. If the brain to the corresponding facts of con- you ask him whence is this "Matter" of VOL. IV. 72 which we have been discoursing, who or what | may offer itself to terrestrial, if not to human divided it into molecules, who or what im- investigation. Meanwhile, the mystery is not pressed upon them this necessity of running into without its uses. It certainly may be made a inorganic forms, he has no answer. Science power in the human soul; but it is a power is mute in reply to these questions. The pro- which has feeling, not knowledge, for its base. cess of things upon this earth has been one of It may be, and will be, and we hope is turned amelioration. It is a long way from the to account, both in steadying and strengtheniguanodon and his contemporaries to the pre-ing the intellect, and in rescuing man from sident and members of the British Association. A time may, therefore, come when this ultrascientific region by which we are now enfolded that littleness to which, in the struggle for existence, or for precedence in the world, he is continually prone. JOHN CRAWFORD WILSON. [John Crawford Wilson was born at Mallow, county Cork, on the 20th April, 1825, but he has passed the great part of his life in London. He is favourably known as a poet, dramatist, and miscellaneous writer. His chief poetical works are, The Village Pearl, and other Poems, 1852; Elise and Flights to Fairy Land, 1865; Lost and Found, a pastoral, 1865. His most important dramas are Gitanilla and a stage version of his poem Lost and Found. Jonathan Oldaker, or Leaves from the Diary of a Commercial Travellera bright and amusing series of sketches and tales has passed through several editions. For eighteen years Mr. Wilson has been a member of the Dramatic Authors' Society, and is president of the Whitefriars' Club, a literary association which he was chiefly instrumental in founding. Among his fugitive pieces, which have been highly praised, we find Eight Hours at the Sea-side, a sketch, and A New Ode to St. Patrick, a poem. "As an author," says a reviewer, "Mr. Wilson has been eminently successful, the scenes he depicts and the characters he introduces being calculated to promote a thrilling interest, nor is he wanting in that quality of pathos which invests a story, where requisite, with solemn and sober touches." "To the moral qualities which distinguish poets Mr. Wilson may lay an undoubted claim," says the Athenæum. "Genuine feeling is so infectious that such a writer can hardly tell a plain and pathetic story to unsympathizing readers." The greater number of the author's poems depict the pathetic and tender feelings of our nature, and among these his poem Home takes a high place. In Lost and Found, the most ambitious of his poetical efforts, he depicts a heroine They called her "Lily"-Lilian was her name— |