CHARLES MARIE DE LA, a practical geographer and cultivator of science in general, son of Charles de la Condamine, a receiver-general of finances, and Margaret Louise de Chources, was born the 28th of January 1701.

His early education was by no means neglected, although he complains, in a manuscript memoir which he left respecting the progress of his studies, and the development of his faculties, that he was made to learn, as boys frequently are, too much by rote, without understanding the complete sense and bearing of the words which he repeated. It is, however, by no means certain that any great loss of time is ultimately incurred by this practice; for in fact the memory is much strengthened by the constant habit of getting by heart, and it does not appear that the judgment is at all impaired by it. He afterwards pursued his studies under Father Brissou, and in 1717 supported a thesis on the Cartesian philosophy, which the Jesuits were then beginning to introduce into their seminaries, while it was elsewhere giving way to the Newtonian. In 1719, after he had left college, he entered the army, and accompanied his uncle, the Chevalier de Chources, to the siege of Rossas, as a volunteer; and both on this and other occasions he exhibited sufficient proofs of the contempt of danger and the spirit of enterprise which were so much required in those pursuits that afterwards occupied a considerable portion of his life. Notwithstanding the dissipations in which military men are very commonly involved, he was moderate in the pursuit of pleasure; and he used to consider the distortion which the small-pox had left in his features as having afforded him some compensation for the injury done to his vanity, by diminishing the temptations to which his sensibility might otherwise have exposed him.

Having no prospect of speedy advancement in the army, and having suffered considerably in his fortune from a participation in the extravagant speculations of Law, he quitted the service, in hopes of finding a more advantageous employment in science. He distinguished himself as an active member of a society of arts, then recently established at Paris by the Count de Clermont; and, in 1730, he obtained a situation in the Academy of Sciences, as adjunct of the class of chemistry, having previously presented to the academy a memoir on the mathematical and mechanical properties of the lathe, which obtained him considerable credit. Soon afterwards he embarked in the squadron of Duguay Trouin, and made a voyage in different parts of the Mediterranean; he passed several months at Constantinople, and visited the plain of Troy, and many other parts of the Levant; after his return he gave an account of his tour to the academy; and a servant, who had accompanied him, published also a separate journal of his own.

Chemistry, as it was cultivated at that period, afforded but little scope for the employment of an active mind; and La Condamine, after the publication of one chemical memoir only, was removed from the class of chemists in the academy to that of astronomers. In this capacity he was the first to propose the measurement of a degree of latitude in the neighbourhood of the equator; and he seems to have felt the importance of the undertaking, not only for the purpose of deciding a great question in science, but also for that of attracting the attention of the public, and establishing the system of gravitation in France by a grand operation, executed, with great labour and at a great distance, by Frenchmen only. His ideas were readily seconded by Maurepas, then prime minister; and he was appointed by the academy, together with Bouguer and Godin, for carrying the proposal into effect.

In this expedition he was absent from his country for nearly ten years, from 1735 to 1745; and he had to combat with difficulties of every kind. A distant voyage; an uncivilized and sometimes uninhabited country; impracticable roads; want of regular remittances; the necessity of disposing of valuable articles disadvantageously, in order to procure a temporary supply; a malicious prosecution upon the pretence of a contraband traffic, founded only on this circumstance; and the still more violent attacks of a fanatical mob, who murdered the surgeon of the expedition: all these things, to say nothing of the awful appearance of an eruption of Cotopaxi, and the no less formidable operations of the hostile squadron of Lord Anson, required nothing less than the dauntless spirit and energy of character which he possessed, to bear him up against them; and at last the little jealousies, which will often arise among persons of science employed in the same pursuits, embarrassed and embittered the conclusion of his enterprise. The activity and fluency of La Condamine made the public disposed to imagine that Bouguer had been only his humble attendant; and Bouguer was too conscious of his own superiority as a mathematician to bear this injustice with patience. He complained, but the laugh was against him; and he revenged himself by refusing all communication in the statement of the results of the operations; so that each observer gave ultimately a separate account of his own measurements and calculations.

In consequence of all the fatigues and vicissitudes to which La Condamine had been exposed, he became extremely deaf, and partially paralytic, after his return; but the powers of his mind appear to have remained unimpaired.

In 1748 he was elected a foreign member of the Royal Society of London; and he afterwards exerted himself with great zeal and success in promoting, among his countrymen, the general introduction of the variolous inoculation, which had long been practised in England, and in some other parts of Europe. In 1757 he took a journey to Italy, and spent a considerable time at Rome, partly with a view to the improvement of his health, and to the observation of a variety of facts connected with his scientific pursuits; but principally, perhaps, in order to obtain a dispensation from the pope for a marriage with his niece, who seems to have had a high respect for his talents, and even a sincere attachment to his person, notwithstanding the disparity of their ages, and the caprices of a temper not a little impatient and irritable. He became, in 1760, one of the forty members of the French Academy, and contributed considerably to an improved edition of their dictionary. In 1763 he paid a short visit to England, which was rendered less agreeable to him on account of the difficulty that he found in obtaining legal redress for some slight injury which he had received; after his return, the insensibility of his limbs increased, and he was obliged to relinquish all his pursuits of science, retaining only the amusement of making some light attempts in poetry, and occasionally inserting in the periodical works of the day a few tales in verse, besides a poetical translation of a part of Virgil's *Enée*; although it seems natural to suppose that the exercise of the inventive fancy of a poet would tend to exhaust the debilitated faculties even still more than the methodical investigation of mathematical or physical subjects.

1. The first of Mr. de la Condamine's publications was a *Memoir on the Conic Sections*, M. Ac. Par. 1731, p. 240. It contains a comparison of the equations of the various parallel sections of a given cone with that of the surface of the cone itself; but it is not remarkably distinguished either for clearness of conception or for accuracy of expression.

2. *On Metallic Vegetation*, M. Ac. Par. 1731, p. 466, H. P. 31. The experiments described in this paper relate to the precipitation of nitrate of silver, or other metallic solutions, placed upon a flat surface of glass or agate, by means of an iron nail; and the only remarkable circumstance attending them is the extension of the ramifications to parts at a considerable distance from the nail which supplies the iron in the place of the silver deposited, exhibiting a faint resemblance of the astonishing transfers and interchanges which have been more lately discovered in electro-chemical experiments.

3. *Observations made in the Levant*, M. Ac. Par. 1732, p. 295; relating principally to navigation, to geography, and to natural history. The author had agreed to undertake an expedition into the interior of Africa; but his arrangements were interrupted for want of the expected co-operation.

4. *Account of an Instrument for determining a Parallel Circle on the Earth's Surface*, M. Ac. Par. 1733, p. 294, H. P. 53; a telescope fixed perpendicularly on an axis parallel to that of the earth, and consequently capable of being directed only to objects situated in the parallel circle required, proper allowance being made for the effects of refraction.

5. *Description of a Variation Compass*, M. Ac. Par. 1733, p. 446. A wire is fixed in the axis of the card, and a graduated ring of paper round its circumference, half above and half below, on which the shadow of the wire is to fall at sunset.

6. *Two Memoirs on the Lathe*, M. Ac. Par. 1734, p. 216, 295. A description of the rosette and of other parts of the figure lathe, with a mathematical determination of the epicycloids, conchoids, and other curves, which are traced by their combination. The apparatus is represented among the machines approved by the academy, vol. v. p. 83, 89.

7. *A Letter relating to the Variation Compass*, M. Ac. Par. 1734, p. 597; containing testimonials in its favour, with a mode of observing, by looking directly at the wire, and at the setting sun when his light is too faint to cast a shadow.

8. *On the Determination of small Differences of Longitude*, M. Ac. Par. 1735, p. 1; a discussion of the kinds of signals best adapted for contemporaneous observations at a distance; a subject much more difficult at that time than at present, when the art of pyrotechny has been carried to so high a degree of perfection, especially since the late singular invention of a rocket with a parachute, descending slowly, and exhibiting successive explosions.

9. *Measurement of the Length of the Pendulum at St Domingo*, M. Ac. Par. 1735, p. 529. The academicians were detained at St Domingo more than three months, and they took advantage of the delay in order to ascertain the length of the pendulum in that latitude. Mr. de Condamine employed a ball of brass, suspended by a thread of the aloe, and attached to it by means of a piece of sticking plaster; the pendulum making a vibration in about two seconds, he observed in how many vibrations a second was lost or gained. The length thus determined was thirty-six French inches seven and a quarter lines, or 39'0125 English inches. Messrs Godin and Bouguer made it one twelfth of a line longer, or 39'020; and a calculation from the best modern observations for the latitude, which was 18° 27', gives us 39'029. The thread was fixed by a clip, and it was probably very flexible, since its rigidity must necessarily have tended to increase the curvature of the path of the ball, and to give a measure somewhat too long. See the article *Coifion*.

10. *Account of the Quinquina Tree*, M. Ac. Par. 1738, p. 226. Jussieu, who was the botanist of the expedition, had pointed out to La Condamine a number of circumstances respecting the cinchona, which required investigation; and he was enabled to illustrate them in a satisfactory manner, from having to pass through Loxia in the course of his investigations. It appears that the bark known under the name of quina-quina before the discovery of the cinchona, was the cascarilla; and these two articles have sometimes been confounded, though very different in their nature and effects.

11. *Abstract of a Journey through a part of South America*, M. Ac. Par. 1745, p. 391, H. 63. After the completion of the operations at Quito, Mr. de la Condamine determined to take the course of the river Maranon for his return towards Cayenne; and in the course of this route, of more than 2000 miles, which he performed partly by land, but principally on a raft, he had an opportunity of making a multitude of interesting observations of various kinds. He found in several places a singular agreement of traditions respecting the former existence of a republic of women only, in the neighbourhood of the river which has received its most usual denomination from them. He observed the effect of the tides at Pauxis, a point 600 miles from the mouth of the river, but not much elevated above it; and he was informed that there were always a number of alternations at high and low water at the same time between this point and the mouth of the river; in some places, where the water was shallow, he encountered the tide rising in the form of a bore, called by the French a barre or snasearet, and by the inhabitants there a poroca, occupying but one or two minutes in its ascent, and frequently producing accidents to boats unprepared for its reception. After his arrival at Para, he measured the length of the pendulum there, and found that the force of gravitation was about $\frac{1}{100}$ greater than at the summit of Pichincha. He next proceeded to Cayenne, and was obliged, on account of the war, to return to Europe by a Dutch ship, which sailed from Surinam.

12. *Abstract of the Geographical Operations performed in South America*, M. Ac. Par. 1746, p. 618. The length of a degree at the equator appears, from these calculations, to be 56,750 toises. Bouguer, who employs the same determination of the arc, but a different series of trigonometrical observations, makes it 56,753; and Godin, on the other hand, somewhat less than Condamine. This is more than 300 toises less than the degree measured in France, and almost 700 less than the degree in Lapland; and it gives for the earth's ellipticity, by comparison with the former, $\frac{3}{25}$, and with the latter $\frac{1}{17}$. The terminations of the base were marked by pyramids, and the length of the toise was identified by a bar of metal let into a tablet of marble, with an appropriate inscription.

13. *Mesure des Trois premiers Degrés du Méridien*, 4. Par. 1751, with a complete journal of the operations. 14. A Proposal for an Invariable Standard of Measures, M. Ac. Par. 1747, p. 489, H. P. 82. Many arguments are advanced in favour of the uniformity of measures in all countries; and the length of the pendulum at the equator is considered as the most proper for universal adoption as the fundamental unit.

15. Account of an Elastic Resin, M. Ac. Par. 1751, p. 319, H. P. 17; a description of several trees affording the calucho, or caoutchouc, especially of the Hheve, or syringe trees, chiefly from Mr Fresneau's communications.

16. A History of the Various Inoculation, M. Ac. Par. 1754, p. 615; a candid, clear, and judicious statement of the advantages of the inoculated above the natural small-pox, in a popular and sometimes even playful style, calculated to meet the prejudices of the day, and the various superstitious and interested motives which retarded the practice in France, while it had become universally prevalent in England; although, in more recent times, the public spirit in this country appears to be somewhat less favourably disposed to the admission of beneficial innovations; for scarcely in any part of the world has vaccination become less universal than it is at this time in Great Britain.

17. Abstract of a Journey in Italy, M. Ac. Par. 1757, p. 336, H. P. 6. From an examination of several ancient standards, and from a comparison of the remains of buildings supposed to have occupied a certain round number of feet, Mr de la Condamine concludes that the old Roman foot was equal to 130-9 French lines; that is, to 969 thousandths of an English foot. Mr Folkes had before made it 966; but Mr Raper has shown, in the Philosophical Transactions for 1760, by a very careful comparison of a multitude of documents, that, before the reign of Titus, it somewhat exceeded 970, and under Severus and Diocletian it was less than 965; the original standard in the temple of Juno Moneta having probably been destroyed by fire. Mr de la Condamine also viewed the races on the Corso with an eye equally mathematical, and observed that the Barbary horses ran at the rate of about forty English feet in a second; but his correspondents in England furnished him with unexceptionable evidence that the horse Childers run the four mile course at Newmarket at the rate of very nearly fifty English feet in a second, while no other horse exceeded forty-eight; and he observes that, in this instance, truth far outruns probability; a remark which has been somewhat misrepresented in this country, and converted, by the lovers of the amusements of the turf, into a laugh against the lovers of the amusements of science; the story being told as if the French mathematicians had demonstrated the absolute maximum of a horse's utmost possible speed, and, a bet having been made on the occasion, an English horse had been found that actually exceeded the maximum. Our author also notices the awkward effect of the Roman mode of beginning the day at sunset, which renders it necessary to make continual alterations in the clocks, directions being given in the almanacs for putting them forwards or backwards a quarter of an hour at a time; and the precise time of noon happening in summer at sixteen o'clock, and in winter not till nineteen. He observes that a single signal, properly placed on the Apennines, would be visible at once near Trieste and near Monaco, giving a difference of longitude of not less than five degrees.

18, 19. On Inoculation, M. Ac. Par. 1758, p. 439; 1765, p. 505.

20, 21. Mr de la Condamine published also a series of Lettres sur les Dictionnaires, and another of Lettres sur l'Education.

In 1768 his name is mentioned as having excited the attention of the members of the academy by a relation of Spallanzani's experiments on the reproduction of the heads of snails, which several of them repeated with success. In fact, there was scarcely any one of the sciences to which he did not occasionally render some service, although he wanted patience and perseverance to make any very important discoveries or improvements by his individual exertions only. But his knowledge was universal; he understood and wrote all languages; he corresponded with men of celebrity in all countries; he published upon all subjects; he contributed to all the literary and scientific journals of the day; he answered all criticisms, and he accepted all compliments, even from persons whom he despised; for he delighted in the parade of a pre-eminent reputation. His style was simple and natural, somewhat negligent, but still elegant and lively; his manner was animated and somewhat singular; his temper was warm and restless; he sighed for repose, and was incapable of enjoying it; thinking nothing that occurred indifferent to him, and allowing none about him to be idle. He obtained the rank of chevalier in several orders, and was a member of several foreign academies; he had also the appointment of honorary secretary to the Duke of Orleans. At the age of sixty-eight he addressed to his wife an account of his education, and of the earlier progress of his mental faculties, as a practical illustration of his opinions respecting the cultivation of the mind. The memoir was not published; but it is perhaps unfortunate for mankind that men of celebrity seldom find a sufficient motive for communicating candidly to the world the results of such a self-examination. A few years before his death he printed a memorial in behalf of Mr Godin, who had been reduced to indigent circumstances; and he had the pleasure of obtaining for him the assistance which he required. He suffered occasionally from a hernia, and having read of the marvellous cures which some empiric professed to have performed by the application of a caustic, he determined to make the experiment on himself, without the knowledge of his family, and without much hope of success; but he fell a victim to the courage or the curiosity that prompted him to submit to the operation. In the course of the six weeks that he survived, he was still employed in writing or dictating a memoir containing answers to some questions respecting the manners of the Americans. He died on the 4th February 1774, leaving many of his books and instruments by will to the Academy of Sciences. (Hist. Acad. Par. 1774, p. 85.) (t. L.)