Even a statue was capable of impressing this truth upon him. But it was the statue of the man who said of his own features: “This is the face of a man who has struggled energetically”—the man of whose portrait Carlyle says: “Reader, to thee thyself, even now, he has one counsel to give, the secret of his whole poetic alchemy. Think of living! Thy life, were thou the pitifullest of all the sons of earth, is no idle dream, but a solemn reality. It is thy own; it is all thou hast to front eternity with. Work, then, even as he has done and does—Like a star, unhasting yet unresting.” Equally impressive was the effect produced on Professor Tyndall by even the sight of the form of such a man. Finding himself one fine summer evening standing beside a statue of Goethe in a German city, the contemplation of this work of art, which he considered the most suitable memorial for a great man, excited a motive force within his mind, which he thought no purely material influence could generate. “There was then,” he says, “labour before me of the most arduous kind. There were formidable practical difficulties to be overcome, and very small means wherewith to overcome them; and yet I felt that no material means could, as regards the task I had undertaken, plant within me a resolve comparable with that which the contemplation of this statue of Goethe was able to arouse.”
From his youth Tyndall appeared to have a remarkable power, not only of attracting friends, but of retaining them. The circumstances under which he early became acquainted with his life-long friends, General Wynne and Professor Hirst, have already been mentioned. Hirst was scarcely sixteen years of age when he became acquainted with Tyndall, who was ten years older. Though they stood in the relation of pupil and teacher, their intimacy ripened into an enduring friendship which separation heightened rather than dissolved. An incident that occurred while Tyndall was studying at Marburg affords honourable evidence of this fact. The death of a relative in 1849 made Hirst the possessor of a small patrimony, which he determined to divide between himself and his former teacher. He accordingly pressed Professor Tyndall to accept one half of his small fortune, but much to his disappointment Tyndall would have none of it. Entreaties to accept it for friendship’s sake were unavailing, but friendship, like necessity, can invent strange means for attaining its end. Hirst took counsel with a German banker as to a way of conveying the money to his friend, and soon a device was carried out, by means of which the devotee of science had to sacrifice his self-denial on the altar of friendship. While at work one morning in his lodgings in Marburg the postman brought him a heavy roll closely packed and sealed, which, to his astonishment, contained all sorts of German coins amounting to 20l. sterling, a considerable gratuity for a student to receive in those days. He had no alternative but to accept it. On a subsequent occasion when Tyndall left Marburg to visit England another friend of his youth, General Wynne, offered to replenish his exchequer, which he feared must be nearly empty, but the offer was declined with assurances that such generous assistance was unnecessary.
CHAPTER II.
“No man ever yet made great discoveries in Science who was not impelled by an abstracted love.”—Sir Humphry Davy.
At the time when Professor Tyndall was studying at Marburg University, the principal figure there was Bunsen, who had been appointed Professor of Chemistry in 1838. He was a profound chemist, and his fame as a lecturer was so eminent as to attract many foreign students. A prolific discoverer, and peculiarly happy in his manner of demonstrating his scientific teaching, he soon fascinated the ardent minds of the two students from Queenswood. For two years Tyndall attended his chemical lectures. Indeed he learned German chiefly by listening to Bunsen. He has himself stated that Bunsen treated him like a brother, giving his time, space, and appliances, for the benefit of his studies. The subject which most attracted Tyndall’s attention was electro-chemistry, upon which Bunsen delivered an admirable course of lectures in 1848. The whole principle of the voltaic pile was thus explained to him in a masterful manner. He also made himself acquainted with chemical analyses, both quantitative and qualitative. He displayed no less zeal in the study of mathematics. For a considerable period he got private lessons from Professor Stegmann, under whose tuition he worked through analytical geometry of two and three dimensions, the Differential and Integral Calculus, and part of the Calculus of Variations.
His first scientific paper was a mathematical essay on screw surfaces, respecting which he says:—“Professor Stegmann gave me the subject of my dissertation when I took my degree: its title in English was, ‘On a Screw Surface with Inclined Generatrix, and on the Conditions of Equilibrium on such Surfaces.’ I resolved that if I could not, without the slightest aid accomplish the work from beginning to end it should not be accomplished at all. Wandering among the pine wood and pondering the subject, I became more and more master of it; and when my dissertation was handed in to the Philosophical Faculty it did not contain a thought that was not my own.”
But the man whose acquaintance at Marburg appeared to exercise most influence over his career was Dr. Knoblauch, who had just come thither from Berlin as extraordinary Professor of Physics, and who had already distinguished himself by his researches in radiant heat. He illustrated his lectures with a choice collection of apparatus brought from Berlin; and he not only suggested to Tyndall an exhaustive series of experiments bearing on a newly-discovered principle of physics, but supplied him with the necessary apparatus, and placed his own cabinet at his disposal for that purpose. The subject of investigation was diamagnetism.
Faraday’s discoveries and experiments in magnetism were then attracting the attention of the scientific world. He had shown in 1830 that by moving a magnet within the hollow of a coil of copper wire an electrical current was produced in the wire. This was a startling and pregnant discovery. Taking six hundred feet of insulated copper wire and winding it into a large vertical coil, he arranged the two ends of the wire into a small coil a little distance away from the large coil, and immediately above this small coil he suspended a balanced compass needle by a silk thread. Then, on dropping a bar magnet, or piece of iron magnetised, into the large coil, the needle, which was pointing towards the North Pole, instantly swung round, evidently impelled by magnetic force; when, again, the bar magnet was raised out of the hollow of the large coil, the needle moved round in the opposite direction; while it remained motionless so long as the bar magnet was at rest either inside or outside the coil. It thus appeared that an electrical current could be produced by the movement of the bar magnet—by dropping it into the coil or taking it out; and the current so produced he called an induced current. This operation is called magneto-electric induction. In 1845 Faraday greatly extended his magnetic discoveries. He not only established the magnetic condition of all matter by showing that every known body or thing could be influenced by magnetism, but he discovered a new property of magnetism, which he called diamagnetism. This was considered his greatest discovery.
By suspending bodies of an elongated form between the ends or poles of powerful magnets, he found that every substance was attracted or repelled from the magnetic poles; and he divided all bodies into two great classes, called magnetic and diamagnetic. The way in which a piece of iron is attracted by the poles or ends of a horseshoe magnet is a familiar illustration of the action of magnetic bodies, and the position that such bodies assume, pointing in a line from one pole to the other, he termed axial. On the other hand, diamagnetic bodies were those which, when freely suspended within the influence of the magnet, assumed a position at right angles to the line joining the poles of a magnet, or to the magnetic meridian; in other words, magnetic bodies pointed axially from pole to pole, or north and south; while diamagnetic bodies pointed east and west, or in an equatorial direction. Bismuth is a conspicuous example of diamagnetic substances. Scientific curiosity soon became excited as to the exact nature of the diamagnetic force in relation to crystals, some of which behaved in a mysterious manner between the poles of a magnet. Professor Plücker, of Bonn, discovered that some crystals formed of diamagnetic substances were not subject to the diamagnetic force; and to account for this he attributed to crystals an optical axis, upon which the poles of a magnet exercised a peculiar force. Plücker brought this theory before the British Association in 1848, and called it a new magnetic action. At the close of the same year, Faraday told the Royal Society that he had often been embarrassed by the anomalous magnetic results given by small cylinders of bismuth, and after investigation he referred these effects to the crystalline condition of the bismuth. In concluding his lecture on this subject, Faraday said:—“How rapidly the knowledge of molecular forces grows upon us, and how strikingly every investigation tends to develop more and more their importance, and their extreme attraction as an object of study. A few years ago, magnetism was to us an occult power affecting only a few bodies: now it is found to influence all bodies, and to possess the most intimate relations with electricity, heat, chemical action, light, crystallisation, and, through it, with the forces concerned in cohesion.” He thought there was in crystals a directive impelling force distinct from the magnetic and diamagnetic force.
Frequent conversations on this subject took place between Knoblauch and Tyndall in Germany during 1849. Knoblauch suggested that Tyndall should repeat the experiments of Plücker and Faraday; and as this operation was proceeding they agreed to make a joint inquiry into the deportment of crystals under the diamagnetic force. They laboured long at the problem before attaining any encouraging success. They examined the optical properties of crystals as well as made magnetic experiments with them, a great many experiments being made without discovering any new fact. Eventually, however, they found that various crystals did not act in accordance with the principles enunciated by Plücker, and the more they worked at the subject the more clearly it appeared that the deportment of certain bodies under the influence of magnetism was due, not to the presence of some force previously unknown, but to the crystalline structure of the substance under investigation, or as Tyndall put it, to peculiarities of material aggregation. For example, he showed that while a bar of iron attracted by a magnet sets itself in a line from pole to pole, an iron bar made of an aggregate of small bars sets itself in the opposite direction. Tyndall showed that the cause of the latter bar assuming an equatorial position was simply its mechanical structure, the small plates composing the “aggregated” bar setting from pole to pole. He found that the same law regulated the magnetic deportment of crystals, whose mechanism or structure, however, was generally less evident.