The death of this distinguished man must be recorded. An interesting
_résumé_ of his labors by M. Daubree has appeared, from which we take
the following facts. After a training in his native town at the Lyceum
of Metz, which furnished so many scholars to the Polytechnic school,
Delesse was admitted at the age of twenty to this school. In 1839 he
left to enter the Corps des Mines. From the beginning of his career the
student engineer applied himself with ardor to the sciences to which
he was to devote his entire existence. The journeys which he undertook
then, and continued later, in France, Germany, Poland, England, and
Ireland, helped to confirm and develop the bent of his mind. He soon
arrived at important scientific results, and was rewarded, in 1845, by
having conferred to him by the university the course of mineralogy and
geology in the Faculty at Besançon, where Delesse at the same time
fulfilled the duties of engineer of mines. Five years later he returned
to Paris, where he continued his university duties, at first as deputy
of the course of geology at the Sorbonne, then as master of the
conferences at the Superior Normal School. Besides this, he continued
his profession of engineer of mines as inspector of the roads of Paris.
The first original researches of the young _savant_ concern pure
mineralogy; he studied a certain number of species, of which the
chemical nature was yet uncertain or altogether unknown, and his name
was appended to one of the species which he defined. He studied
also, and with success, the interesting modifications called
pseudomorphism--the mode of association of minerals, as well as their
magnetic properties. The attributes of a practical mineralogist aided
him greatly in the culture of a branch of geology to which Delesse has
rendered eminent services, in the recognition of rocks of igneous origin
and of others allied to them. He studied in the field, as well as by
investigations in the laboratory, for fifteen years, with an intelligent
and indefatigable perseverance, and, aided by the results of hundreds of
analyses, eruptive masses of the most varied kind, the knowledge derived
from which threw light upon the principles of science, from granites
and syenites to melaphyres and basalts. After thirty years of study
and progress, other _savants_, without differing from him, progressed
further in the intimate knowledge of rocks; but the historian of
science will not forget that Delesse was the precursor of this order
of research. His studies of metamorphism will long do him honor. The
mineralogical modifications which the eruptive rocks have undergone in
the mass are the permanent witnesses which attracted all his attention.
The chemical comparison of the metamorphic with the normal rock pointed
out distinctly the nature of the substances acquired or lost. One of the
principal results of these analyses has been to lessen the importance
attributed until then to heat alone, and to show in more than one case
the intervention of thermal sources and of other emanations from below,
to which the eruptive rocks have simply opened up tracks.
It is not only upon subjects relating to the history of rocks that
Delesse has touched. Witness his work on the infiltration of water, as
well as his volume relating to the materials of construction, published
on the occasion of the Exhibition of 1855. The nature of the deposits
which operate continually at the bottom of the sea offers points of
interest which well repay the labor of the geologist. He finds there,
indeed, a precious field to be compared with stratified deposits; for
in spite of the enormous depth to which they form a part of continents,
they are of analogous origin. Delesse laboriously studied the products
of the innumerable soundings taken in most of the seas. He arranged the
results in a work which has become classical with the beautiful atlas of
submarine drawings which accompany it. Though he never slackened in his
own especial work, he made much of the work of others. The "Revue des
Progrès de la Géologie," with which he enriched the "Annales des Mines"
for twenty years, would have been sufficient to engross the time of a
less active scientific man, and one less ready to grasp the opening of a
discovery. This indefatigable theorist never neglected the applications
of science: the nature and the changes of the layers which form the
under earth; the course and the depth of the subterraneous sheets of
water; the mineralogical composition of the earth's vegetation, were
represented by him on several charts and plans drawn out in proper form.
His maps which follow the route of many of the great French lines of
railway explain the kind of soil upon which they are laid, and are of
daily use. In the pursuit of his numerous scientific works, Delesse
never failed in discharging his duties in the Corps des Mines. Having
in 1864 quitted the service of the Government of Paris, which he had
occupied for eighteen years, he was made professor of agriculture, of
drainage, and irrigation, at the School of Mines, where he established
instruction in these before being called to found the course of geology
at the Agricultural Institution. Promoted to be Inspector-General of
Mines in 1878, and charged with the division of the south east of
France, he preserved to the end of his life these new duties, for which,
to the regret of the School of Mines, he gave up his excellent lessons
there. During the year of 1870 Delesse fulfilled his duties as a
citizen, as engineer in preparation of cartridges in the department.
His nomination to the Academy of Sciences, which took place on the 6th
of January, 1879, satisfied the ambition of his life. He was for two
years President of the Central Commission of the Geographical Society;
he was also President of the Geological Society. He was not long to
enjoy the noble position acquired by his intelligence and his work.
He suffered from a serious malady, which, however, did not weaken his
intellect, and he continued from his bed of suffering to prepare the
reports for the Council-General of Mines, and that which recently he
addressed to the Academy on the occasion of his election. The greatness
and the rectitude of mind of Delesse, his astounding power of work, his
profound knowledge of science, his sympathetic sweetness, which were
associated with sterling modesty and loyalty of character, made him
esteemed and cherished throughout his whole career. He died on the 24th
of March.--_The Engineer._
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[Illustration: SUGGESTIONS IN DECOTATIVE ART.--SILVER EWER, BY ODIOT,
PARIS.
(From The Workshop)]
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