The "Naturanschauung' to which he was led by deep and laborious study finds expression in his Address to the Association of Physicists in 1886: "The deeper we penetrate into the harmonious and immutable order of nature, and unveil her hidden forces, the more modestly do we come to think of the little compass of our knowledge, and the more intense is our admiration of the supreme ordering Wisdom which pervades the whole created world."1

Wilhelm Weber († 1891), one of the celebrated Seven of Göttingen, who in 1837 surrendered their posts rather than swear allegiance to the new government, stands in the first rank of German physicists. He worked at the theory of wave-motion, and acoustics, but above all at electricity. His celebrated electro-dynamic law is indeed no longer accepted, but even his critics admit that Weber's conception bears the stamp of genius, and it held the allegiance of scientists for a long time 2. Weber is also remembered for his contributions to the measurement of electricity, and he was, with Gauss, the first to apply (in 1833) the galvanic current to telegraphy.

4

Reinke includes Weber in his list of great scientists who were also believers. A somewhat longer biography which we have seen, although entering as little as possible

the great workshop of Nature, there are no lines of demarcation to be drawn between the most exalted speculation and commonplace practice, and that all knowledge must lead up to one great result, that of an intelligent recognition of the Creator through his works" (Report of the 52nd meeting of the British Association for the Advancement of Science, held at Southampton in August 1882 [London 1883]. President's Address p. 33)

1 Ib. 170.

2 H. Hertz, Über die Beziehungen zwischen Licht und Elektrizität, Bonn 1889, 7.

3 J. Reinke, Die Welt als Tat, Berlin 1903, 468.

Leopoldina XXVIII, Halle 1892, 147 169 178 185 201.

into religious questions testifies that he "preserved all his life the heart and faith of a child"1. We find in it the following account of his death: "At midday he fell asleep, seated in an arm-chair. As the sun was sinking in the West he awoke again, and his eyes, bright and eager, strained out into the distance; their gaze was no longer fixed on the things of earth but uplifted to that sublimer reality for which his heart had so long hungered." We have in this passage, despite the somewhat rhetorical style, clear evidence of Weber's belief in the immortality of the soul.

William Robert Grove († 1896), who also took electricity for his province, says at the close of his celebrated book "On the Correlation of Physical Forces":

"It is a great assistance in such investigations to be intimately convinced that no physical phenomenon can stand alone: each is inevitably connected with anterior changes, and is inevitably productive of consequential changes, each with the other, and all with time and space; and, either in tracing back these antecedents, or following up their consequents, many new phenomena hitherto believed distinct will be connected and explained: explanation is, indeed, only relative to something more familiar, not more known, i. e. known as to causative or creative agencies.

In all phenomena the more closely they are investigated, the more are we convinced that, humanly speaking neither matter nor force can be created, and that an essential cause is unattainable.

Causation is the will, Creation, the act,

1 Ib. 201.

2 Ib. 204.

3 W. R. Grove, On the Correlation of Physical Forces: being

the substance of a course of lectures delivered in the London Institution in the year 1843, London 1846, 48 50.

Kneller, Christianity.

10

2. THE THEORY OF LIGHT.

To the second half of the 19th century belong the development of the theory of electricity, and the establishment of the mechanical theory of heat. The first half saw, indeed, the discovery of many fundamental laws of electricity, but it is significant in the history of science mainly for the formulation of the modern theory of light. Fresnel, Fraunhofer, Fizeau, Foucault are the names that come to everyone's lips in this connection; it is to their labours that we owe the current conception which regards light, not as a substance, but as a wave-motion in the ether.

The external life of the great Augustin Fresnel1 is soon told. Born on May 10th 1788 at Broglie in the Department of Eure, he received his early education at home, and subsequently went to the Central School in Caen, to the Polytechnic, and to the School of Engineering in Paris. He then obtained a post as engineer in the North of France. When Napoleon returned from Elba, Fresnel considered himself bound as a good Royalist to take service in the army of the South. The outcome was that he secured leisure for scientific studies; for after the triumph of Napoleon he was deprived of his position as engineer and placed under police supervision. Fresnel now began his investigations into the nature of light; and, thanks to the kindness of his superiors, he was able to continue them after his resto

1 Euvres Complètes d'Augustin Fresnel, publiées par MM. Henri de Senarmont, Émile Verdet et Léonor Fresnel, 3 vols, Paris 1866 f. Duleau, Notice sur A. Fresnel, printed in the Rev. Encyclopédique XXXIX, livr. 117, Paris, Septembre 1828, 558-567.

ration to office. The essays published by him during 1819-1827 on refraction, interference, and related subjects are few in number, but every one of them is a masterpiece. He also made many improvements in the apparatus used in lighthouses. He died young, not yet forty, on July 14th 1827, at Ville d'Avray near Paris.

The famous physicist came of a deeply religious family. Thus his mother writes in 1802 in reply to a letter from his elder brother asking news of Augustin, then at college: "I pray God to give my son the grace to employ the great talents, which he has received, for his own benefit, and for the God of all. Much will be asked from him to whom much has been given, and most will be required of him who has received most.” 1 Augustin inherited this religious habit of mind. During the early years of his life as an engineer he was almost friendless, and was cast wholly on his own resources. He sought distraction in study, and with all the greater ardour inasmuch as he had never any taste for the practical life. "But the first inclination of his life was by no means to optics. Under the influence of a home education in which religion had held the first place he began to reflect on philosophical problems, and endeavoured to reach a rigorously scientific proof of certain of those doctrines to which he adhered with an ardent belief. But he never opened his mind on these questions save to members of his family or to his most intimate friends." 2

1 Euvres Complètes I, Paris 1866, XCVIII.

2 Sous l'influence des souvenirs d'une éducation de famille où la religion avait tenu la première place, il commença à méditer sur les questions philosophiques et s'efforça de trouver une démonstration

ΙΟ

The editor of Fresnel's scientific works shows little inclination to dwell on the religious side of his character, but in spite of this we find many proofs that the great scientist remained all his life an adherent of the "Spiritual School" 1. We find notes for instance of an essay in defence of the doctrine of immortality forwarded by Fresnel to a sceptical uncle of his.

Fresnel's piety of disposition remained unaltered down to the last moment of his life. His friend, the engineer Duleau, who nursed him in his last illness, tells us that the constant theme of his conversation was the greatness of God, Whose power and wisdom he saw manifested in every part of nature. He always regarded his own intellectual endowments as a gift from God, and held it a duty to employ them for the advance of knowledge and the benefit of his fellow men. The thought of his untimely death and of the works he was compelled to leave unfinished, in no way troubled his devotion; there was something higher, he said, for mankind than science and genius 2.

scientifique et rigoureuse de la vérité de quelques-unes des croyances qui avaient été jadis pour lui l'objet de la foi la plus ardente; mais il ne communiqua jamais ses pensées qu'aux membres de sa famille et à ses plus intimes amis (Œuvres Complètes I XXVIII).

1 On August 5th 1811, Léonor Mérimée writes to his nephew Aug. Fresnel: "J'ai serré dans mon tiroir ta lettre philosophique, pour la reprendre quand j'aurai le loisir de débrouiller ma case de métaphysique." Here Léonor Fresnel makes the marginal note: “Il s'agit sans doute d'un essai psychologique, où A. Fresnel développe les principaux arguments sur lesquels se fonde la doctrine spiritualiste, dont il fut toujours défenseur” (Ib. II [1868] 811).

2 "Il a vu approcher sa fin avec les sentiments religieux d'un homme qui, ayant été initié plus avant que ses semblables dans le secret des merveilles de la nature, était profondément pénétré de la puissance