The time is not yet come when a memoir of the personal life of Delambre
could be attempted with any chance of interesting the reader. The
accounts which have been published from authentic sources are very
meagre; and, as may be supposed, this country is not the place in which
better can be obtained. We must therefore content ourselves with
offering a slight table of the principal events of his public career,
and proceed to give some account of his extraordinary labours.
Jean Baptist Joseph Delambre was born September 19, 1749, at or near
Amiens. He studied under Delille at the college of Plessis, applying
himself particularly to the learned languages. His accurate and ready
knowledge of Greek afterwards proved an element of no mean importance in
the merit of his ‘History of Astronomy.’
Though the extent of his works would give the idea of a very long life
applied to one subject in all its bearings, yet Delambre was more than
thirty years old before he turned his attention to astronomy. It is said
that he accidentally entered the room where Lalande was delivering a
lecture on some part of that science, while either waiting for or coming
from another on the Greek language. Be that as it may, he commenced his
studies under the celebrated astronomer just named before 1785, in which
year the calculation of the longitudes and latitudes of the stars in
Mayer’s Catalogue, by Delambre, was published, in the ‘Connaissance des
Tems’ for 1788. In 1789 he published Tables of Jupiter and Saturn; and
in 1790 Tables of Uranus, which gained the prize of the Academy of
Sciences; at the same time he was actively engaged in correcting, by
observation, the existing tables of right ascensions. In 1791 he
published new Tables of Jupiter’s Satellites, which Lalande calls “Un
des plus grands travaux astronomiques qu’on ait faits.”
In 1792 Delambre aided Lalande in calculating the planetary tables for
the third edition of his ‘Astronomy;’ and was appointed a member of the
Institute, and also of the Commission for measuring a Degree of the
Meridian. Of his share in this operation we shall presently speak. In
the same year he published his first Tables of the Sun, and a second set
in 1806, together with Tables of Refraction. In 1817 he again
constructed Tables of Jupiter’s Satellites. In 1795 he was appointed to
the _Bureau des Longitudes_; in 1802 he was made _Inspecteur Général des
Etudes_, in which capacity he formed the Lyceums of Moulins and Lyons.
In 1803 he became perpetual secretary of the class of mathematics in the
Institute, and the various _éloges_ which are found in the Memoirs of
that body till 1822 are from his pen. In 1807 he succeeded Lalande as
Professor at the College of France; in 1808 he was appointed Treasurer
of the University, and in 1821, Officer of the Legion of Honour. He died
August 19, 1822, at the age of seventy-three.
The dry catalogue of tables and works becomes curious and interesting
when we consider them all as the production of one man, who was also
actively engaged either on the great Survey or in continual observation.
But the list is yet far from complete. The Histories of Astronomy
(_Ancienne_, _Moyenne_, _Moderne_, _du dix-huitième Siècle_), comprised
in six volumes 4to., appeared between 1817 and 1821, with the exception
of the last, which was published in 1827, after the author’s death. His
large work on astronomy, in three 4to. volumes, came out in 1814, and
the ‘Base du Systême Métrique,’ a detailed account of the operations of
the Survey, in four volumes 4to. (of which the first three are the work
of Delambre), appeared at different times between 1806 and 1810. He had
previously (in 1799 if we recollect rightly) published a shorter
description of the methods employed. His decimal tables of Logarithms
appeared in 1801, and his Report on the Progress of all the Sciences
since 1789 was presented to the Emperor Napoleon in 1808, and published
in 1810. We have still to add the numerous memoirs which he contributed
to the ‘Connaissance des Tems,’ the ‘Memoirs of the Institute,’ and
other periodicals, to the list of Delambre’s labours; a list which shows
that he possessed a degree of energy rarely surpassed, and a quantity of
reading, on the subject of astronomy at least, certainly never equalled.
But though it is only justice to the memory of Delambre to insist upon
the amazing _quantity_ of work which he performed, all of the first
order of utility, in which he appears to us to stand altogether without
a rival in the history of science, we have yet to point out how much of
that work was of a more laborious character than is usually necessary to
produce the same number of pages. We need not dwell on the planetary
tables, &c., or on the ‘Base du Systême Métrique,’ almost every page of
which is a separate record of toil and patience. The History of
Astronomy is a work of a peculiar kind. It is not merely a digest of
ideas which the author had acquired from the perusal of the writings of
others, but an actual abstract of every work which has exercised the
least influence on the progress of the science, whether Greek, Arabian,
or modern European. This task by itself would have been abundantly
sufficient to secure to its author the reputation of a long life well
spent; for he had to wade through the writings of every age and country,
and in particular to acquire a knowledge of the mathematical styles of
different times, which are sufficiently distinct to render them, we
might almost say, sciences of different species. The student of
astronomical history is thus with very little trouble put in possession
of all the records of the only science whose history is a part of
itself, and must be studied with it. If the author sometimes appears
prejudiced or hasty in his conclusions, it must be recollected that
(intentional misquotation of course apart, of which he was never
suspected) the plan of the work is such as to render the conclusions
which a reader may draw from it, to a great degree independent of any
colouring arising from the bias or misconception of the author.
The ‘History’ of Delambre was preceded by that of Bailly, a work of such
totally different character, that the description of it after the other
may almost seem exaggerated for the sake of contrast. With much general
knowledge, and, perhaps, considerable research, but with too much
previous self-instruction what to find, Bailly has made conjectures of
his wishes, and positive theories of his conjectures. His fanciful
accounts of people whom he has caused, as has been observed, to give us
all knowledge, except that of their own name and existence, perhaps
drove Delambre a little into the other extreme: it so, the circumstance
is not to be regretted; and the reader, who has amused himself with the
former, by inventing inventors for all that has ever been invented, may
fall back upon the latter, to learn how many of his conclusions are
founded on the rational basis of written testimony. A strong
predilection for the latter kind of evidence is the characteristic of
Delambre’s writings; and if familiarity with the Greeks rendered him
somewhat prejudiced in their favour, he has but paid too much interest
for a large and acknowledged debt; whereas Bailly has squandered his
whole substance upon creatures of his own imagination.
A very striking feature of Delambre’s writings upon the history of
astronomy, is the avidity with which he throws himself upon any
calculation which comes in his way, repulsive as such details are to
writers in general. Not content with the fullest numerical exposition of
the process as practised by the astronomer he is describing, he
frequently adds the modern method of doing the same thing. This is one
of the most useful parts of his undertaking; for astronomy is not, as so
many imagine, only the art of looking at the heavens, but also of
knowing what to do with the results of observation; and Delambre, in his
character of an unwearied calculator, has been of more use than the most
assiduous observer[5] of his day.
Footnote 5:
We are far from undervaluing the higher species of observation which,
when combined with the sagacity of the inventor, finds new general
laws. We speak only of the vulgar notion entertained of an astronomer,
which, however excusable in the general ignorance of the science,
portrays only a part of the character, useful indeed, but not the most
difficult.
But in the character of an observer Delambre was conspicuous. In
conducting his part of the Survey, we cannot help admiring his fortitude
as well as skill. In a letter to Lalande, written in 1797, he thus
expresses himself, and it is no exaggerated instance of the impediments
he frequently met with: “I had about six hours’ work, and I could not do
it in less than ten days. In the morning I mounted to the signal, which
I left at sunset. The nearest inn was that at Salers, to which it took
me three hours to go, and as much to return, and the road was the worst
I have met with. At last I resolved to take up my lodging in a
neighbouring cowhouse; I say neighbouring, because it was only at the
distance of an hour’s walk. During these ten days I could not take off
my clothes; I slept upon hay, and lived on milk and cheese. All this
time I could hardly ever get sight of the two objects at once; and
during the observations, as well as in the long intervals which they
left, I was alternately burned by the sun, frozen by the wind, and
drenched by the rain. I passed thus ten or twelve hours every day,
exposed to all the inclemency of the weather; but nothing annoyed me so
much as the inaction.”
It was with extreme difficulty that permission to encounter these
inconveniences was granted. The republican government, which, in its
hurry to change the weights and measures,[6] had ordered the commission,
began to fear lest a latent tinge of royalism in some one of their
agents might infect the new standard. At least such a suspicion forces
itself upon us, when we find that “The Committee of Public Safety,
considering how important it was to the amelioration of the public mind
that those employed by government,” in the Survey for instance, “should
be distinguished,” not by their knowledge of the theodolite and
repeating circle, but “by their republican virtues and hatred of kings,”
struck Delambre and others off the list, and would have served Méchain
in the same way (who was on the frontier, with public money in his
possession), had not they found within themselves the suspicion that he
would play them false. But we must not be less than just to the
instances of liberal feeling which the most bigoted times produce. When
Delambre returned to Paris, he was allowed, after some hesitation, to
retain the diploma of the Royal Society of London, written in Latin,
with the arms of the King of England upon it.
Footnote 6:
For some of our readers we may state that the object was the
measurement of the earth’s circumference, or rather the deduction of
it from the measurement of a part, in order that the metre might be
made an exact aliquot part of the circumference.
Such were the feelings with which the government regarded even their own
favourite project, and we may therefore be surprised at the endurance
with which Delambre solicited, and at length partially obtained, leave
to recommence his operations; add to which, that his astronomical
instruments caused him frequently to be molested as a spy by the
ignorant populace of the departments—a fact nowise to be wondered at,
when we remember that at Paris Lalande’s observatory was searched for
arms, and the tube of a telescope carried off to the authorities as some
strange species of gun.
Delambre did not interfere in politics; it would have been strange
indeed if he had found time. It was amply sufficient for one man to link
his name to the science of astronomy, past, present, and future, by
history, observations, and tables.
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