Account of the Life and Writings of Reaumur.
Birth and Education of Reaumur—He settles at Paris, where he is introduced to the Scientific World by the President Henault, and becomes a Member of the Academy of Sciences—His Labours for the Improvement of the Arts—His Works on Natural History, of which the Memoirs on Insects are the most important—His Occupations and Mode of Life.
René Antoine Ferchault de Reaumur, one of the most ingenious naturalists whom France has produced, was born at Rochelle in 1683. He commenced his studies in his native place, continued them at Poitiers under the Jesuits, and finished his professional course at Bourges; but feeling less inclined to the practice of law than to the investigations of natural science, he resolved to devote himself entirely to the latter. In this respect he was the more justified in following his inclination, that he possessed a fortune sufficient to support him without engaging in any occupation merely to procure the means of subsistence. He began to prepare for his new pursuits by studying mathematics, and when he thought his proficiency such as to qualify him to make a respectable figure among the naturalists and philosophers of the capital, he removed thither in the year 1703.
The President Henault, who held a distinguished station among the literati of Paris, and who was his relative, introduced him to the scientific world. In 1708, when only twenty-four years of age, he presented some geometrical memoirs to the Academy of Sciences, who were so much pleased with his performance as to admit him into their society,—an honour which he enjoyed nearly fifty years. His exertions were directed successively to the improvement of the arts, to natural philosophy, and to natural history. From his entrance into the academy he scarcely allowed a year to pass without publishing some work of importance. Soon after his admission he was appointed to assist in drawing up a description of certain arts and trades; but not confining himself to a simple elucidation, he endeavoured also to improve them, by applying the principles of physics and chemistry. On the other hand, by observing the ingenious combinations employed in some of the arts, he had frequent opportunities of adding to his knowledge of the phenomena of nature.
In his inquiries into the business of ropemaking, for example, he proved by conclusive experiments that, contrary to the common opinion, twisting impairs the strength of ropes. Again, while describing the labours of the goldbeater, he took occasion to show the prodigious ductility possessed by certain substances. But, more especially, when examining the processes by which artificial pearls are coloured, he discovered the singular matter which gives lustre to the scales of fishes, and even explained the formation and growth of those scales. The colouring principle in glass pearls is obtained from the bleak (Cyprinus alburnus), an inhabitant of fresh water, and about six inches in length. This silvery ingredient is procured by macerating its scales in water, and is then mixed with a little isinglass. The small globes which are to represent pearls are first furnished with an internal coating of the solution, and then filled with melted wax to give them suitable weight. The pearly matter occurs also in the membrane which envelopes the stomach and intestines, and is supposed by Reaumur to be produced in the latter, from which it is conveyed by the blood-vessels to the scales. He likewise made inquiries into the formation and growth of shells, which he proved to be developed by accessions to their outer edge. He is even said to have examined the structure of pearls, with the view of forcing the shell-fish to produce them. When describing the turquoise-mines of the south of France, and the means adopted to make the mineral assume a blue colour, he discovered that these alleged stones were the teeth of a large animal, which is now known under the name of the mastodon.
His most important labours, however, with reference to the arts, were his researches respecting iron and steel, which he published in 1722, in a separate work under the title of Traité sur l'art de convertir le fer en acier, et d'adoucir le fer fondu. At this period all the steel that was used in France was imported, none having previously been made in that country; and one may imagine how numerous and patient were the trials made by Reaumur before he succeeded in his object. The Duke of Orleans rewarded him for this valuable discovery, by bestowing on him a pension of 12,000 livres. In like manner, he found out the method of manufacturing tin-plate or whiteiron, which until then had been brought from Germany. In his various experiments, he had frequent occasion to observe that melted metals assume regular forms on cooling, and he accordingly gave an account of the crystallizations which they present. The manufacture of porcelain also engaged his attention, and received considerable improvements from him, although he did not succeed in perfecting it. In 1739, he made known a method which he had discovered of giving a whiteness and opacity to glass, which causes it to assume the appearance of chinaware. He was also the first who tried in France the expedient practised by the Egyptians for hatching eggs,—a subject which, being of a nature suited to popular apprehension, procured for him at least as much estimation as all his other researches.
In Great Britain his fame seems to rest almost entirely on his peculiar scheme of graduating the thermometer. He chose the extreme points of the freezing and boiling of water, which, under similar circumstances, are always fixed and unvarying. The interval between these points he divided into eighty degrees, upon the principle that spirit of wine, in a certain state of rectification, expands 80,000 parts. In his experiments on this subject he arrived at some valuable conclusions, in regard to the varieties in their volume and temperature which are exhibited by particular fluids when combined, as well as on frigorific mixtures. He also carefully collected the observations on heat made in different places by means of his thermometer.
The importance and utility of these researches are unquestionable, and yet there is even more of novelty and interest in those which he made in natural history. For instance, he explained the means by which many shells, sea-stars, and other mollusca or zoophytes, execute their progressive motion. He likewise illustrated the curious manner in which the claws of crabs and lobsters are reproduced. He also threw a new light on the singular action of the torpedo, and the organ by means of which it is exercised, although the phenomena of electricity were not then sufficiently understood to enable him to perceive all the relations of his subject. In 1718, he published a memoir on the rivers of France, which contain grains of gold in their sands, and soon after described the immense beds of fossil shells known in Touraine under the name of falun. In 1723, he made observations on the lustre emitted by several kinds of shell-fish, especially the pholades, which perforate wood and stones.
Physiology is indebted to him for the ingenious and decisive experiments which, in 1752, made known the difference that exists, with respect to digestion, between birds of prey, whose stomach acts on their food only by means of a solvent fluid, and granivorous birds, in which a very powerful muscular gizzard exercises a pressure sufficient to break down the hardest bodies and reduce them to powder.
These labours might well have sufficed for a single life; but the most remarkable undertaking of Reaumur has not yet been mentioned. It is entitled Memoires pour servir à l'Histoire des Insectes, and extends to six quarto volumes, which were published between 1734 and 1742. This work occupied many years, and was the result of numerous observations made principally in his own garden, where he kept insects of all kinds, for the purpose of examining their habits, changes, and generation. It is, however, incomplete,—the locusts and grashoppers, as well as the whole tribe of coleoptera, having been intended for subsequent volumes, which never appeared.