But notwithstanding the crude and uncritical nature of the writings of the second half of the eighteenth century, resulting from the lack of that more careful and detailed observation which characterizes our day, there was during this period a widespread interest in physical and natural science, and it led up to that more exact study of nature which signalizes the nineteenth century. “More new truths concerning the external world,” says Buckle, “were discovered in France during the latter half of the eighteenth century than during all preceding periods put together.”[66] As Perkins[67] says: “Interest in scientific study, as in political investigation, seemed to rise suddenly from almost complete inactivity to extraordinary development. In both departments English thinkers had led the way, but if the impulse to such investigations came from without, the work done in France in every branch of scientific research during the eighteenth century was excelled by no other nation, and England alone could assert any claim to results of equal importance. The researches of Coulomb in electricity, of Buffon in geology, of Lavoisier in chemistry, of Daubenton in comparative anatomy, carried still farther by their illustrious successors towards the close of the century, did much to establish conceptions of the universe and its laws upon a scientific basis.” And not only did Rousseau make botany fashionable, but Goldsmith wrote from Paris in 1755: “I have seen as bright a circle of beauty at the chemical lectures of Rouelle as gracing the court of Versailles.” Petit lectured on astronomy to crowded houses, and among his listeners were gentlemen and ladies of fashion, as well as professional students.[68] The popularizers of science during this period were Voltaire, Montesquieu, Alembert, Diderot, and other encyclopædists.
Here should be mentioned one of Buffon’s contemporaries and countrymen; one who was the first true field geologist, an observer rather than a compiler or theorist. This was Jean E. Guettard (1715–1786). He published, says Sir Archibald Geikie, in his valuable work, The Founders of Geology, about two hundred papers on a wide range of scientific subjects, besides half a dozen quarto volumes of his observations, together with many excellent plates. Geikie also states that he is undoubtedly entitled to rank among the first great pioneers of modern geology. He was the first (1751) to make a geological map of northern France, and roughly traced the limits of his three bands or formations from France across the southeastern English counties. In his work on “The degradation of mountains effected in our time by heavy rains, rivers, and the sea,”[69] he states that the sea is the most potent destroyer of the land, and that the material thus removed is deposited either on the land or along the shores of the sea. He thought that the levels of the valleys are at present being raised, owing to the deposit of detritus in them. He points out that the deposits laid down by the ocean do not extend far out to sea, “that consequently the elevations of new mountains in the sea, by the deposition of sediment, is a process very difficult to conceive; that the transport of the sediment as far as the equator is not less improbable; and that still more difficult to accept is the suggestion that the sediment from our continent is carried into the seas of the New World. In short, we are still very little advanced towards the theory of the earth as it now exists.” Guettard was the first to discover the volcanoes of Auvergne, but he was “hopelessly wrong” in regard to the origin of basalt, forestalling Werner in his mistakes as to its aqueous origin. He was thus the first Neptunist, while, as Geikie states, his “observations in Auvergne practically started the Vulcanist camp.”
We now come to Lamarck’s own time. He must have been familiar with the results of Pallas’s travels in Russia and Siberia (1793–94). The distinguished German zoölogist and geologist, besides working out the geology of the Ural Mountains, showed, in 1777, that there was a general law in the formation of all mountain chains composed chiefly of primary rocks;[70] the granitic axis being flanked by schists, and these by fossiliferous strata. From his observations made on the Volga and about its mouth, he presented proofs of the former extension, in comparatively recent times, of the Caspian Sea. But still more pregnant and remarkable was his discovery of an entire rhinoceros, with its flesh and skin, in the frozen soil of Siberia. His memoir on this animal places him among the forerunners of, if not within the ranks of, the founders of palæontology.
Meanwhile Soldani, an Italian, had, in 1780, shown that the limestone strata of Italy had accumulated in a deep sea, at least far from land, and he was the first to observe the alternation of marine and fresh-water strata in the Paris basin.
Lamarck must have taken much interest in the famous controversy between the Vulcanists and Neptunists. He visited Freyburg in 1771; whether he met Werner is not known, as Werner began to lecture in 1775. He must have personally known Faujas of Paris, who, in 1779, published his description of the volcanoes of Vivarais and Velay; while Desmarest’s (1725–1815) elaborate work on the volcanoes of Auvergne, published in 1774, in which he proved the igneous origin of basalt, was the best piece of geological exploration which had yet been accomplished, and is still a classic.[71]
Werner (1750–1817), the propounder of the Neptunian theory, was one of the founders of modern geology and of palæontology. His work entitled Ueber die aüssern Kennzeichen der Fossilien appeared in 1774; his Kurze Klassifikation und Beschreibung der Gebirgsarten in 1787. He discovered the law of the superposition of stratified rocks, though he wrongly considered volcanic rocks, such as basalt, to be of aqueous origin, being as he supposed formed of chemical precipitates from water. But he was the first to state that the age of different formations can be told by their fossils, certain species being confined to particular beds, while others ranged throughout whole formations, and others seemed to occur in several different formations; “the original species found in these formations appearing to have been so constituted as to live through a variety of changes which had destroyed hundreds of other species which we find confined to particular beds.”[72] His views as regards fossils, as Jameson states, were probably not known to Cuvier, and it is more than doubtful whether Lamarck knew of them. He observed that fossils appear first in “transition” or palæozoic strata, and were mainly corals and molluscs; that in the older carboniferous rocks the fossils are of higher types, such as fish and amphibious animals; while in the tertiary or alluvial strata occur the remains of birds and quadrupeds. He thought that marine plants were more ancient than land plants. His studies led him to infer that the fossils contained in the oldest rocks are very different from any of the species of the present time; that the newer the formation, the more do the remains approach in form to the organic beings of the present creation, and that in the very latest formations, fossil remains of species now existing occur. Such advanced views as these would seem to entitle Werner to rank as one of the founders of palæontology.[73]
Hutton’s Theory of the Earth appeared in 1785, and in a more developed state, as a separate work, in 1795.[74] “The ruins of an older world,” he said, “are visible in the present structure of our planet, and the strata which now compose our continents have been once beneath the sea, and were formed out of the waste of preëxisting continents. The same forces are still destroying, by chemical decomposition or mechanical violence, even the hardest rocks, and transporting the materials to the sea, where they are spread out and form strata analogous to those of more ancient date. Although loosely deposited along the bottom of the ocean, they became afterwards altered and consolidated by volcanic heat, and were then heaved up, fractured, and contorted.” Again he said: “In the economy of the world I can find no traces of a beginning, no prospect of an end.” As Lyell remarks: “Hutton imagined that the continents were first gradually destroyed by aqueous degradation, and when their ruins had furnished materials for new continents, they were upheaved by violent convulsions. He therefore required alternate periods of general disturbance and repose.”
To Hutton, therefore, we are indebted for the idea of the immensity of the duration of time. He was the forerunner of Lyell and of the uniformitarian school of geologists.
Hutton observed that fossils characterized certain strata, but the value of fossils as time-marks and the principle of the superposition of stratified fossiliferous rocks were still more clearly established by William Smith, an English surveyor, in 1790. Meanwhile the Abbé Haüy, the founder of crystallography, was in 1802 Professor of Mineralogy in the Jardin des Plantes.