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III The Men from Across La Manche: French Voyages, 1660-1790
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The Men from Across La Manche: French Voyages, 1660-1790

Seymour Chapin

Enormous contrasts can be drawn about conditions in France between the opening and closing dates of this survey. No matter where one looks, those hundred and thirty years resulted in alterations of considerable significance. In the political arena, the year 1660 saw Louis XIV take the decision to be his own first minister and, with that, to begin the rise of the absolute monarchy to its zenith. By 1790, however, the process of limiting the monarchy's power was already well under way at the hands of the National Constituent Assembly, and the republican sentiment that was to bring its complete downfall was at least in its embryonic stage. Socially in 1660 France was a hierarchically organized state in which all individuals were defined by the order to which they belonged. By 1790, however, the concept of orders had been replaced by that of la patrie . Economically France was, in 1660, on the verge of becoming—thanks to Colbert—the most thoroughgoing mercantilistic nation in Europe. By 1790, however, the stage had been set for at least the beginnings of a substitu-


tion of a free-enterprise, laissez-faire system for the previous Colbertism. One could doubtless evoke many other such broad examples, but it seems preferable to come quickly to the specific subjects of this study: scientific and geographical discovery.

This is obviously not the place to attempt even the most cursory summary of one hundred and thirty years of scientific development—especially these years which, after all, saw the dilettante savant converted into the professional scientist. That comment will, however, allow one to offer at least one general contrast to parallel those already made, since the principal agency of that transformation was the Académie Royale des Sciences. Thus the year 1660 found France six years from the creation of that central and well-subsidized institution for the promotion of scientific research. The year 1790, on the other hand, saw the French nation only three years away from destroying that academy, which it may be argued had lived out most of its truly useful existence. A multitude of sciences had progressed greatly under its aegis—to the point, in fact, where other, more specialized, centers had emerged to provide new foci and new support.[1] Several of these sciences and institutions had important roles to play in scientific and geographical expeditions. We shall be concerned here with a few of them. I should like to stress at the outset, however, that my emphasis will be upon such matters as astronomy, navigation, geodesy, and cartography and not at all upon the rather separate though very significant tradition of voyaging in the interests of natural history.[2]

Coming now to geography, one might offer several broad contrasts between French presences on the globe in 1660 and those in 1790. Overseas, France in 1660 was well established in the West at those rapids in the St. Lawrence River that Cartier had ironically named La Chine. By 1790, however, that Canadian springboard into Louisiana had passed into English hands while Louisiana itself had been divided between Spain and the young United States. In the East there was, in 1660, virtually nothing French be-


yond the Cape of Good Hope. And France's subsequent Indian Ocean presence had again diminished by 1790. Beyond there, or from around Cape Horn, Frenchmen had not passed—except as sailors on the ships of Magellan and others—by 1660. By 1790, however, they had left their mark—and their markers of possession—on a significant number of Pacific locations and were exploring the possibilities of a fur trade between the northwest coast of North America and La Chine the country.[3] Finally, one might conclude this set of contrasts by pointing to the fact that France itself had undergone considerable change during this period, adding large territories on its east by military, legal, and diplomatic action while losing lands on its west to the Atlantic Ocean.

This latter loss was the result of scientifically based mapping operations and can, thereby, serve to get us on with our subject—after two general remarks. The first is simply a disclaimer: the survey I shall be presenting makes no pretense to being definitive; indeed, it will probably appear rather selective. The reason for that brings me to my second observation: while it has become almost commonplace to point out that exploration in the eighteenth century became more scientific as the century progressed, that view is based far more upon the English experience than upon the French. Thus some effort at a demonstration of this point and, more specifically, of a contention that the French were more scientific all along will be one of my major concerns— an objective that has, naturally, somewhat controlled my choice of examples.

In 1663 an account of a French voyage of the early sixteenth century was published. In the early summer of 1503, a ship named L'Espoir , under the command of a Captain Gonneville, left Normandy and sailed south into the Atlantic. The following November, when somewhere in the vicinity of the Cape of Good Hope, she encountered violent storms and was blown off course. In early January 1504, L'Espoir reached a land where her crew, well treated by the natives, was able to repair the ship and lay in stores


for the return trip. When the ship finally arrived back in France in the spring of 1505, she carried on board the son of a local king of what came to be known as Gonneville's Land. It was a descendant of that passenger, Jean Paulmier de Courtonne, canon of St. Peter's cathedral in Lisieux, who published the 1663 account of the voyage of L'Espoir , accompanied by a plea for a missionary expedition to his people.[4]

It would be tempting to see the appearance of this pamphlet, a second printing of which was issued in 1664, as at least a partial motivation for the founding in that year of the Compagnie des Indes Orientales. Such would not seem to be at all the case, however, for two major reasons. First, the location of Gonneville's Land was unknown, for the captain's report contained neither bearings of any kind nor any estimates of either latitude or longitude. It was generally assumed that it must lie somewhere in the southern ocean, but precise guesses ranged widely and the whole affair was attended with such vagueness that this mysterious region had to wait until the next century to have its real impact. The second reason is simply that since 1604 there had appeared no less than four French companies which had proposed to establish commerce with the East Indies, but they had profited from their privileges only to send isolated ships to distant parts and to found on Madagascar (sometimes suggested as the actual landfall of Gonneville) a colony that was on the point of extinction by 1664.[5] The company that Colbert then founded under the special protection of Louis XIV aimed at reversing that pattern of failure.

That the new association seemed destined to a brilliant future was a product of its being part and parcel of Colbert's whole economic program. That plan, which gave due consideration to foreign commerce, tariffs, the merchant marine, and the navy, was colored by his hostility to the English and Dutch—especially the latter, a hostility which had its origins in mercantilist principles.[6]

Of particular interest here is that Colbert's program also


predisposed the French to take a great interest in the marine clocks of the Dutch scientist Christian Huygens. Having converted Galileo's discovery of the isochronism of the pendulum into an accurate timepiece in 1656,[7] Huygens had, in 1662, developed a marine variation employing a short pendulum which had subsequently been subjected to tests at sea with the aid of the English. News of this device having come to Colbert through one of his advisers, the new director of France's economic life was determined to secure its advantages for his nation. Accordingly, Huygens was lured to Paris in 1665.[8]

About a year after his arrival there he became one of the original members of the Académie Royale des Sciences, the creation of which was yet another reflection of Colbert's sweeping program aimed at establishing France's economic preeminence. Thus the Académie was to be the government's select body of consultative experts. They were to engage, for example, in a complete description of the arts and crafts in France aimed at introducing the benefits of scientific theory into the practices of the workshops. Of far greater importance to present purposes, they were to play an important role in achieving another of Colbert's broad goals: the exact mapping of his monarch's kingdom.[9]

That aim fitted in very well with the extensive astronomical program proposed for the Académie during its earliest sessions by Adrien Auzout, including a call for the creation of a royal observatory in Paris. And it was undoubtedly that same desire which brought new additions into the Académie. One of these, Jean Picard, was probably the closest approximation to a "professional" astronomer then to be found in France.[10] The other addition of significance had to be imported into that nation. This was Giovanni Domenico Cassini, whose tables of the motions of Jupiter's satellites—published in Bologna in 1668—had, because they were accurate enough to predict the eclipses of those bodies, finally rendered practicable Galileo's idea for reading them as the hands of a celestial


clock in the determination of longitudinal differences.[11] Small wonder that Cassini was invited to enjoy a large pension from the Sun King on the condition of taking up residence in Paris, where he assumed membership in the Académie and a leading role in the affairs of the observatory then being constructed.

As successful as it was for utilization on land, the technique of Jupiter's satellites was not applicable at sea— largely because of the difficulty of making precise observations through a long telescope on the deck of a swaying ship. But determining longitude at sea was, as we have seen, a major concern in France at this time.[12] Indeed, one of the activities called for by Auzout as early as January 1667 was for the sending of a scientific expedition to Madagascar. The memoir in which he spelled out its manifold aims is the first clear statement of what constitutes a truly "scientific expedition" as opposed to a broad but ill-defined voyage of collection. It has appropriately been said that the carefully planned journey "by a trained scientist for the investigation of significant problems or phenomena was a remarkable innovation"[13] it should be emphasized, in keeping with my earlier contention, that it was an innovation which appeared in the Paris Académie des Sciences within three weeks of its official beginning. One of the goals of this first suggested program was, as would be expected, the testing of Huygens' marine clocks. And although the full Madagascar expedition had to be postponed because of political and economic considerations, Colbert pushed ahead with more restricted and utilitarian voyages.[14] Thus during 1668 and 1669 two voyages to test the clocks were made in the Mediterranean with one of the Académie's assistants, a M. Delavoye, in charge of the instruments. The first test produced quite unsatisfactory results—for which Huygens partially blamed Delavoye's handling—but the second greatly encouraged all involved. Indeed it now seemed vital to send the clocks on a more extensive voyage, and the Madagascar possibility surfaced once again. That was not destined to come about, but its


place was taken, in 1670, by a voyage to Acadia, perhaps thought to be a more appropriate destination—thanks to its east-west rather than primarily north-south orientation—for attempts at longitude determination. I say attempts because, as things developed, this voyage was to test two methods for achieving that goal, precisely the two methods that were ultimately to prove successful a hundred years later: the chronometer and lunar-distance methods. They were far from successful in 1670. Thus the clocks, now confided to Jean Richer, another of the Académie's students, had been stopped by an encounter with a storm shortly after the ship's departure from La Rochelle, while no records at all remain of the efforts of a M. Deshayes to employ the technique known as lunar distances.

The situation was quite different on land. There the academicians—especially in the person of Picard—were carrying through a revolution in observational astronomy made possible by Huygens' astronomical pendulum clock, the filar micrometer perfected (if not invented) by Auzout, and the application of telescopes to large-scale graduated instruments appropriate for the measure of small angles.[15] It was with this equipment that Picard undertook to measure the distance between two localities approximately on the meridian of Paris, to determine the differences in their latitudes, and to deduce from those results the length of a degree of meridian. That eminently successful arc measure, marked by a precision thirty to forty times greater than any previously achieved, became the basis on which the desired rectification of French cartography could be— and was—carried out.[16]

The Académie also continued its interest in expeditions abroad. Thus, in July 1671, Picard traveled to Denmark for the purpose of establishing the exact location of Tycho Brahe's observatory of Uraniborg and the longitudinal separation of that site from Paris in order to be able to utilize the Danish astronomer's star catalog effectively. And in September of that same year Richer was dispatched to Cayenne to conduct many of the astronomical observa-


tions originally slated for Madagascar but also to take advantage of the proximity that Mars would have to Earth in 1672 in order to deduce, by means of corresponding observations made by Cassini in Paris, a new and improved figure for the parallax of the sun. The dimensions of the solar system were to be improved along with those of France. One important outcome of the Richer expedition, to which we shall return momentarily, was that he found it necessary to shorten a seconds pendulum that had been accurately adjusted in Paris.[17]

All of this new information—especially the new determinations of latitude and longitude for hundreds of locales—was placed by Cassini upon the large world map that he created at the Royal Observatory. That institution was also the scene of other important works. Thus, for example, it was there that Ole Roemer, who had so impressed Picard while assisting him at Uraniborg that the Frenchman had brought him back to Paris, engaged in his study of the eclipses of Jupiter's satellites that led him to enunciate, in 1676, the finite velocity of light and provide a figure for it.[18] Interestingly, Roemer also contributed to the ever increasing precision of observation through work on the epicycloidal form of the teeth of clock driving wheels.[19] That effort, which found immediate use in improved pendulum clocks, also had applicability for spring-driven clocks which even Huygens was beginning to realize would have to be the basis for effective seagoing timekeepers.[20] Another product of the observatory was the publication of an annual ephemeris, the Connaissance des temps , beginning with a volume devoted to the year 1679.[21]

The result of all this activity was a remarkable improvement in maps and the manner of making them. Indeed, the creation of scientific cartography seems clearly to be a French contribution of the late 1660s and 1670s. This was to be the process that shrank France in the West, although that was actually done separately from the work of the Académie by a group of engineers, whose isolated works


were, however, coordinated by the Académie and furnished information to become publishable in atlas form as Le Neptune François .[22]

In the 1680s this thrust toward scientific locating was continued both in France and overseas. One instance of the latter was the expansion of this activity to China. When Father Fontenay, a Jesuit professor of mathematics at the Collège Louis le Grand who was well aware of the work of Cassini and his colleagues, was then preparing to go there, he volunteered to make as many observations as he could undertake without interfering with his missionary duties. He was duly trained at that observatory before his departure.[23] At the same time, the Académie was organizing another expedition to the West. Thus in the spring of 1682, two of His Majesty's engineers for hydrography, Messrs. Varin and Deshayes, joined by a M. De Glos, a young man trained (as were they) by Cassini, departed from Gorée, a small island off Cape Verde on the west coast of Africa, where a French colony had recently been established by the Compagnie du Sénégal et Côtes d'Afrique. From there they sailed to the West Indies where they spent the better part of a year in extensive observations. Certainly their talents could have been put to good use by René-Robert Cavelier Sieur de La Salle, who had descended the Mississippi to its mouth in 1681, returned to France, and won support for an expedition to plant a colony there.[24] He overshot that destination by some 400 miles, however, and landed in what is now western Texas. Clearly a Cassinitrained scientist might have enabled him to avoid the disaster that ultimately befell the entire undertaking.

The La Salle episode reminds us that various commercial and expansionary developments were not at all associated with the movement being dealt with here. To cite but a few examples, one can point to the expansion from Madagascar into the Mascareines with the founding of centers on the Ile de France and the lie de Bourbon and the further establishment, from there, of a French presence in India. In fact the expansion went beyond there,


for the Jesuits were followed into China by traders, who, naturally, came to be organized in mercantilistic France as the Compagnie de Chine.[25] Moreover, there occurred also a French penetration into the southern ocean across the Pacific when, after the Dutch wars of 1672-1678, French corsairs joined the pirates of the Caribbean in attacking the rich and ill-defended South American colonies along the Pacific coast. That penetration greatly escalated after 1698 and took a new turn, becoming almost legal, with the placing of a Bourbon on the Spanish throne in 1700.[26]

We return to our dominant theme by observing that the War of Spanish Succession which resulted from that action provided an opportunity for French scientists to pay visits to areas previously closed to them. Thus, in 1707, Louis Feuillet—who had earlier accompanied Jacques Cassini, the second member of that astronomical dynasty, on a voyage to the Levant and was later sent to the Caribbean, the aim of both journeys being astronomical observations and the determination of longitudes—was dispatched to the South Seas with instructions to carry out a scientific survey of the Pacific coast and to fix the exact longitudes of its principal parts. Four years later, Amedée François Frézier left to do more of the same, although this time with certain political undertones and with some important Atlantic coast work—such as a survey of Le Maire Strait—on the way. His map of South America has been called "the most accurate and reliable which had so far been drawn."[27]

It was an incident of this same war—namely, the wreck in the Scilly Islands of four ships with the loss of two thousand men of Admiral Shovel's fleet—that gave a new urgency to the search for a solution to the problem of determining longitude at sea. The most famous response to this disaster was the passage of the British act of Parliament in 1714 that provided for a "public reward for such person or persons as shall discover the Longitude" and created the Board of Longitude to administer the distribution of funds.[28] Of equal importance for our purpose,


however, was a parallel development in France—namely, the creation of two prize programs to be developed and directed by the Académie des Sciences on the basis of funds bequeathed to it by one Rouillé de Meslay.[29] The second of these programs was to reward the finding of longitude at sea and discoveries useful to navigation and great voyages. As such, it was to be responsible for a good deal of the work—particularly the construction of marine clocks— that we shall be dealing with here.[30]

Before continuing with the longitude theme, however, we should note another problem that burst upon the scientific scene in that same second decade of the eighteenth century: the puzzle that appeared with Richer's shortening of his seconds pendulum. The need for that action was not immediately explained. Indeed, it was not even accepted by all interested parties—Cassini, for example, was inclined to think that Richer had been mistaken or careless. When the subsequent expedition from Gorée reported the same necessity, however, the search for an explanation became rather pressing. In the interim between those voyages, Huygens had published his epochal Horologium oscillatorium , which provided an equation for the duration of an oscillation of a pendulum in terms of its length and its weight considered as a combination of attraction and centrifugal force.[31] It now was realized, therefore, that the alterations in length must have been necessitated by a change in weight. How was this possible? The answer was soon forthcoming in Newton's monumental Principia , which appeared in 1687 and gave to the world the great principle of universal gravitation. In it, Newton postulated, without demonstration, that the form of equilibrium of a fluid homogeneous mass, subject to the law of attraction and rotating about an axis, is an ellipsoid of revolution about that axis, flattened at the poles.[32] In other words, the earth has the shape of an oblate spheroid, a conclusion with which Huygens agreed in his 1690 work on the cause of weight, even though he did not admit the reciprocal at-


traction of all particles of matter and found a lesser degree of flattening at the poles (or, the same thing in reverse, the bulging of the equator).

Thus by the end of the seventeenth century agreement had been reached as to the oblateness of the earth but not its extent. Operations were then under way, however, which were to contradict the idea of oblateness itself. As early as 1683 it had been decided to extend the arc measured by Picard in both directions. This work, begun by the first Cassini and others, had been interrupted. It was resumed in 1700, however, and carried to completion in 1718 by Jacques Cassini, who published the results of these new measures in 1720.[33]

If the earth has the form of an oblate spheroid, the length of one degree of latitude ought to increase as one moves from the equator toward the poles. In the measure undertaken in France, therefore, a northern extension of the same amplitude as Picard's arc ought to have been slightly longer than the original arc, which, in turn, ought to have exceeded in length a southern extension. The figures published by Jacques Cassini, however, indicated an opposite relationship. Having found that the most southerly portion of the total arc had the greatest length, Cassini and a group of followers maintained that the earth had the shape of a prolate spheroid—elongated rather than flattened at the poles.

It has recently been shown that the dispute between the proponents of oblate and prolate spheroids, known respectively as the Newtonians and the Cassinians, was not simply "a skirmish in the battle between Cartesians and Newtonians" as it had usually been represented—an observation that should have been obvious from the outset when one considers that Huygens' support of oblateness was, after all, derived from Cartesian principles.[34] The new and richer context for the debate has made much more of the fundamental split between solutions from theory and those from observation. That the evidence from


the latter was suspect was first pointed out in 1720 by Joseph Nicolas Delisle, the occupant of a chair of mathematics at the Collège Royal. Delisle set forth reservations about what one could infer about the earth's shape from any local measurements, even those associated with his suggestion for a different approach to the problem—namely, to substitute a measure of a degree of longitude along a parallel to the equator for the measurement of latitudinal lengths.

The memoir in which Delisle enunciated these considerations was not made public at the time of its writing. Nor, in fact, did it come to light for some time thereafter, an outcome that stemmed from his acceptance of an offer from Peter the Great to found an observatory and an associated school of astronomy in Russia. Planned for four years, Delisle's stay in Russia stretched into a twenty-two-year period. While there, incidentally, he and his students engaged in geodetic and cartographic ventures throughout the country, the results of which were intended for a projected but unrealized large-scale and accurate map of Russia.[35] In any event, given his absence from Paris it fell by default to others to carry out or at least to publicize his suggestions. They—particularly Pierre Louis Moreau de Maupertuis—did so in 1733 on the basis of a small book published in Italy in 1729 by Giovanni, the Marquis Poleni, holder of the chair of mathematics at the University of Padua. Like Delisle's unpublished memoir, that booklet (and Maupertuis) urged the utilization of longitudinal measures. Maupertuis read his paper to the Académie when Cassini was away—engaged in the fieldwork necessary to trace across France the arc of the great circle perpendicular to the meridian through Paris. Reporting on this project at a public meeting of the Académie a few months later, Cassini not only insinuated that he had himself arrived at the idea of using longitudinal lengths to determine the earth's shape but that the work already accomplished had again vindicated his prolate spheroid. Delisle,


incidentally, reclaimed his priority by finally printing his ideas in 1737. Considerably before then, however, a solution to the dispute was being sought in another direction.

The real problem with the evidence of the extended measure, as pointed out by Newton himself in the 1726 third edition of his Principia , was that the small differences in length involved could have resulted simply from errors in the operations. One proposed solution to that difficulty was simply to measure degrees of latitude considerably distant from one another. Thus, in 1735, the Académie resolved to send an expedition to measure a degree of latitude near the equator and another to do the same near the pole. Shortly thereafter, two groups of academicians left France; one went to Peru, the other to Lapland.

The expedition to Lapland did not in fact leave until 1736, almost a year after the other. It returned, however, in 1737—seven years before the Peruvian expedition. The account of this northern undertaking was published in 1738 by Maupertuis, who had both promoted and headed it. The arc measured by this expedition was found to be considerably longer than that measured by Picard (Figure 3.1). No wonder that Maupertuis, for a frontispiece to his account, had himself painted bedecked in furs and holding in his hands a globe of the earth that he was squeezing flat at the poles (for another depiction of Maupertuis from his book, see Figure 3.2).[36]

The value of the Lapland degree invalidated the re-suits proclaimed after the prolongation of Picard's arc and necessitated a remeasure of the meridian of Paris. This project was undertaken in 1739 and 1740 under the auspices of the Académie and featured the work of the Abbé Nicolas-Louis de Lacaille and the third member of the Cassini dynasty to be so involved, César-François Cassini de Thury as he liked to fashion himself. The new meridian, known as the Méridienne vérifiée from the title of Cassini III's book describing the operations, reversed the earlier findings and erased any doubts which might have remained.[37] Thus, in 1740, the question was definitely de-


Figure 3.1.
Foldout map following p. 184 in M. de Maupertuis, 
La figure de la terre . . . (Paris, 1738).


Figure 3.2.
Depiction of Maupertuis moving from one station to another in Lapland. 
From M. de Maupertuis, La figure de la terre . . . (Paris, 1738).

cided in favor of the Newtonian theory. The results soon to be brought back from Peru were going to provide further proof of the oblateness of the earth.

As indicated earlier, the Peruvian expedition left France in 1735. It was not until 1744, however, that the first of its members reappeared in Paris. There were several reasons for that long delay, the first of which was simply the difficulty of the operations themselves. Another reason was the friction among those involved.

The leader of the expedition was Louis Godin, who had addressed himself to its object immediately following Maupertuis's memoir and subsequently suggested the equatorial venture.[38] Following those operations he stayed on, as a professor of mathematics at the University of San Marcos, until 1751. Despite later claims that he was working on it, Godin never published his account of the voyage.

Another member of the expedition was Charles-Marie de La Condamine, who in June 1733 had discussed instrumentation to go with Godin's ideas. He returned to France by the longest and most dangerous route, the Amazon. After reaching the Atlantic he went to Cayenne where he repeated the observations of Richer that had initiated the problem more than seventy years earlier. Back in Paris he published, in 1751, a day-by-day account of the expedition


which served as a kind of introduction to the detailed treatment of the geodetic operations which he brought out later that same year. It is rather ironic that, thanks to "his amiable nature and his talent as a writer," La Condamine has received the major part of the credit for the success of the expedition when he was, in fact, a less gifted astronomer than Godin and a less reliable mathematician than the venture's third member, Pierre Bouguer,[39] who was in fact, for our purposes, its most important collaborator.

The son of a royal professor of hydrography, Bouguer was a prodigy who at the age of fifteen, at the death of his father, applied for and obtained the professorship. He quickly became "the leading French theoretical authority on all things nautical," winning Meslay prizes in 1727, 1729, and 1731 on the subjects of the masting of ships, the best way of observing the altitudes of stars at sea, and the observation at sea of the magnetic declination.[40] Becoming an associate geometrician in the Académie in 1731, a most unusual appointment, he seemed a natural choice to accompany Godin and La Condamine. In Peru he engaged in a number of investigations beyond the geodetical work itself. He also, as has been implied, entered into arguments with his colleagues. The first of the three to return to France, he also was the first to set forth his account of the expedition. That publication occurred in 1749,[41] but he continued thereafter to launch a number of polemics, which need not concern us, against La Condamine.

Always good with instruments, in 1748 Bouguer invented the heliometer, a device capable of accurately measuring such small arcs as those involved in determining the diameter of the sun.[42] In 1752 he was named an honorary member of the Académie de Marine established in that year,[43] while in the following year he brought out his Traité de navigation . Although warmly lauded in a report presented to that naval academy, the Traité was written more for scientists than for sailors. It was, however, to be greatly improved upon in that regard in a new edition brought out by Lacaille in 1760, as we shall see shortly.[44]


The new Académie de Marine was a significant creation. It was composed of a liberal cross section of people concerned with naval affairs: officers from the rank of ensign through squadron chief, engineers who dealt with fortifications, artillery, and the various activities of the Dépôt des Cartes et Plans, shipbuilders and pursers, professors of hydrography in certain ports of France, and instructors in mathematics in some of those same places, but mainly those (and especially several Jesuits) associated with the schools devoted to the training of future naval officers, the specially favored Gardes de la Marines.[45] Its works were to be as broad as its membership, starting with the idea, so typical of the eighteenth century, of preparing a dictionary of all nautical terms and concerns. Another of its functions, as suggested by the case of Bouguer's Traité , was to undertake the review of relevant books. Nor were books the only printed objects that came under its scrutiny. Its concern with a mappemonde sent to it by Delisle in 1753 is of special interest.

Delisle had returned to France in 1747, bringing with him vast amounts of geographical and astronomical material. Because of its great value, the French government purchased this collection by giving Delisle a life annuity, an observatory at the Hôtel de Cluny in Paris, and the title of astronome de la marine to go with it. Although he undertook various works in that capacity, he particularly concerned himself with developing the idea, first put forward by Halley, of utilizing the transits of Mercury and Venus across the face of the sun to determine a more accurate figure for solar parallax. His mappemonde was devoted to showing the best locations for observing the transit of Mercury in May 1753. The Académie de Marine was very much interested in it and the phenomenon but was unable to send any expeditions to observe it.

This new institution was also concerned with the tools of astronomical observation. Thus, for example, in 1754 one of its members presented a paper on Hadley's octant which was extensively commented upon by another mem-


ber with a view toward improving the English instruments. Beyond such specific interests, the Académie wanted its own observatory at Brest. In fact, it devoted some time in 1754 to examining a plan for such provided by Pierre-Charles Lemonnier, who had accompanied Maupertuis to Lapland but was more noted for the observations he undertook in his observatory in Paris in the Capucin monastery on Rue St.-Honoré. These were important because they were made with the best instruments then in France, Lemonnier having initiated the practice of acquiring superior large-scale apparatus from English instrument makers and then undertaking to describe them in the volume devoted to astronomical instruments in the Académie des Sciences' Description des arts et métiers .[46] More important for our purposes, however, was Lemonnier's advocacy of a new technique for determining longitude at sea—namely, the method of horary angles of the moon. The major convert to this idea was Alexandre-Guy Pingré a member of the congregation of Ste.-Geneviève in Paris and an assiduous calculator who had been named a correspondent of Lemonnier in the Académie des Sciences in 1753. The following year he prepared a kind of nautical almanac under the title of Etat du ciel which set forth the technique of horary angles.[47] Though praised within the Académie de Marine, the astronomers of the Académie des Sciences found fault with it because of several difficulties and uncertainties.

Chief among these critics was Lacaille, professor of mathematics at the Collège Mazarin where he had an observatory in which he carried out an extensive observational program with much smaller instruments than those of Lemonnier but which, thanks to great care and effort, produced both greater and more accurate results—as shown, among other places, in the ten-year ephemeris that he published for the period 1745 through 1754. Lacaille undertook an expedition to the Cape of Good Hope in 1751. Though primarily intended to expand upon Halley's earlier catalog of southern stars (which it did with


enormous success), the voyage had other goals as well. Since one of these objectives was for a more precise determination of lunar parallax, Lacaille's expedition to the tip of Africa was accompanied by the dispatch of an observer to Berlin, located on the same meridian, to make simultaneous observations. This interest in the moon led Lacaille to examine its use for determining longitude at sea. Unlike Lemonnier, Lacaille reverted to the older idea of lunar distances, and, in fact, he provided a successful demonstration of its use on his return voyage to France.[48] Once back, he addressed himself to the preparation of a new ten-year ephemeris. This time, however, he also made it into a weapon to propagandize for the lunar-distance technique, setting forth explanations of all the necessary calculations and providing a kind of almanac for use at sea in listing the distances from the moon to the sun and a few selected stars for four-hour periods.[49] Subsequently this was one of the key elements that he added to the new edition of Bouguer's Traité de navigation in 1760. Curiously, neither of these works appears to have come before the Académie de Marine, perhaps because, beginning in 1756, its meetings began to suffer from the inroads of the Seven Years' War.

It was about two years later that the editorship of the Connaissance des temps came open. Since this position was given only to associate members of the Académie des Sciences, one obvious candidate for the position was Pingré, who had become an associé libre —the only sort of membership available to regular clerics—in 1756.[50] Rather than giving Pingré the post, however, the Académie, perhaps with the connivance of the navy, awarded it instead to Joseph-Jérôme Lefrançais de Lalande.

Having been sent to Paris to pursue legal studies, Lalande had, in 1749, obtained lodgings in the Hôtel de Cluny.[51] There, of course, he came into contact with De-lisle and was gradually but irretrievably drawn into astronomy, availing himself of courses in that subject taught at the Collège Royal by both Delisle and Lemonnier. He sub-


sequently came also under the influence of Lacaille and, in fact, was his corresponding observer in Berlin. That expedition was followed by other successes—including, near the end of the 1750s, the provision of data to Alexis-Claude Clairaut, the third and final French member of the Lapland expedition and later France's leading theoretical astronomer, for his calculations on the return of Halley's comet, the publication of a new and improved edition of that Englishman's planetary tables, and, increasingly, work with Delisle on the preparation of a mappemonde for the upcoming transit of Venus, which he had come to consider far more appropriate than Mercury's transit for determining parallax.

The transits of Venus, in 1761 and 1769, became the occasions for numerous expeditions, English as well as French, in various parts of the world. Although of great intrinsic interest for scientific voyaging generally, and even of specific interest for geography in their precise latitudinal and longitudinal determinations of their observational locales, these many expeditions, which did not result in the posing of new questions like those arising out of Richer's Cayenne venture, will be touched upon only as they involve other matters of more direct concern to us. Since they have been more than adequately treated by Harry Woolf, there is no need to incorporate them here except to insist that it was Lalande who undertook to analyze the results of all the observations.[52] Far more important for our purposes, however, was his assumption of the editorship of the Connaissance des temps in 1759.

Though Lalande later said that Pingré was denied that post because of his religious affiliation (adding, with uncharacteristic modesty, that Pingré would have done a superior job with it),[53] Lalande was probably chosen because of his known attachment to the method of lunar distances. Certainly he did show himself a proponent of that technique as he undertook to introduce numerous changes into the publication. First he separated from the annual publication all the information and calculations that did not


have to be repeated annually. These he collected and published in a separate book which could be used to accompany the ephemerides for any individual year.[54] Included there were all the instructions necessary to determine longitude by means of lunar distances. Having streamlined the Connaissance des temps , Lalande was now free to add to it current articles in astronomy as well as reviews of new books—thus converting it from a simple ephemeris into what deserves to be called the first specialized scientific journal.[55]

With these accomplishments behind him—as well as having obtained the reversion of Delisle's chair at the Collège Royal, where he began to lecture in 1762—it was as a rather well-known figure that Lalande visited London in 1763, arriving there even before the final acceptance of the peace ending the Seven Years' War.[56] Though not intended for that purpose, his voyage wound up having significance for its connection with the longitude problem. Thus Lalande came to be associated with the effort then under way to have John Harrison reveal the mechanism of his famous No. 4 chronometer that had just returned from a transatlantic voyage during which it had performed well enough to win the highest reward offered by the Act of 1714. He was also made aware of the opposition of several English astronomers to the possibility of awarding that prize to a mere mechanical device. Their desire, instead, was to perfect and reward the technique of lunar distances. That was perhaps especially true of Nevil Maskelyne, who became England's Astronomer Royal in 1765. Rather like Lacaille earlier, Maskelyne had gone to the Southern Hemisphere in 1761—specifically to the island of Saint Helena to observe the transit of Venus—and had used the occasion to demonstrate the usefulness of "lunars" using some of Lacaille's own precepts. Indeed, thanks to the fact that he had been able to utilize new and improved tables of the moon's motions sent to the Board of Longitude by the German astronomer Tobias Mayer, his demonstration was even more effective. As with Lacaille's Ephemerides ,


he had then forcefully recommended the use of the technique in the British Mariner's Guide that he published in 1763.[57]

Lalande's 1763 trip to London can be used as a point of departure for saying something further about the French contributions to the solutions of the longitude problem. One might look first at the matter of the marine clock. I have no intention of attempting to list every French contribution to horology from Roemer's work on. That would involve, among other things, a look at the efforts of Henri Sully and Julien Le Roy in the 1730s and 1740s. Instead, I want to come directly into the 1760s and look, especially, at the work of two men.[58]

One of them, Ferdinand Berthoud, was not actually a Frenchman. Born in Neuchâtel, Berthoud had gone to Paris in 1745, at the age of eighteen, in order to complete his horological studies. Having done so, he then stayed on and gave enough examples of his abilities to earn a considerable reputation. His interest in using these talents in a marine direction manifested itself as early as 20 November 1754 when he deposited at the Académie des Sciences, in the customary manner for establishing priority, a package containing a description of a new marine clock. That early description was followed, at the end of 1760, by a sealed envelope containing a memoir exposing the principles on which he had just built his first example. That memoir was continued in a second some two and a half months later. Small wonder, therefore, that he was selected as the clockmaker to accompany Charles-Etienne-Louis Camus, a member of both the Académie des Sciences and the Académie de Marine, to London to join Lalande in examining Harrison's chef-d'oeuvre.[59] Upon his return from that disappointing venture, he found himself engaged in an intense competition with Pierre Le Roy, a native French clockmaker.

The son of the earlier-mentioned Julien, Le Roy had first contemplated a marine clock at almost the same time


as Berthoud. In fact, his first description was deposited at the Académie less than one month after that of Berthoud, and, like him, he had subsequently undertaken to convert plans into actualities. Apparently upset that Berthoud had been chosen to go to London and thus, presumably, had been granted priority of discovery, Le Roy asked the Académie to open his description on 26 June 1763. Back from London, Berthoud responded in kind on 13 July. This first round thus went to Berthoud, who followed up that success by building several new models.

Berthoud seems to have had enough confidence in his fourth construction to turn the device over to the Académie, which, in turn, ordered it to be tried on board a ship. That was done in the roadstead at Brest in the fall of 1764. On board to carry out the tests were Henri-Louise Duhamel du Monceau—an honorary member of the Académie de Marine and, in Paris, the navy's inspector general and a working member of the Académie des Sciences— and Jean-Baptiste l'Abbé Chappe d'Auteroche, who had entered that institution as an assistant astronomer in 1759 when Lalande had been promoted to the associate level. In their view the results of these tests were far from satisfying. Meanwhile, Le Roy too had been busy. He had submitted a large marine clock to the Académie before the end of 1763, and in the following year he presented a smaller one whose goings were watched for more than a year by Lemonnier although it was not—owing to the lack of funds—subjected to trial at sea.

It was undoubtedly because of all this activity that the Académie was led to propose, as a topic for its Meslay prize in 1767, the best manner of determining time at sea. Le Roy offered this competition a clock that seemed to embody excellent qualities, but it went unrewarded when the judges decided that the prize could not be awarded without a seagoing test.[60] François-César Le Tellier, the marquis de Courtanvaux, an honorary of the Académie and, like many such, a patron of the sciences, then undertook to arrange such a test. Accordingly, Le Roy set out on an ex-


pedition around the North Sea with two clocks which were to be watched by Charles Messier, who, after simply keeping Delisle's observational registers at the Cluny observatory for several years, had succeeded to the use of his instruments there in 1761. Delisle's title of naval astronomer, however, had fallen to Pingré, who was now assigned the task of making the necessary calculations for this test. In slightly over three months on board L'Aurore , Le Roy's clocks performed quite well.[61]

Berthoud had been using that time to improve his devices. In 1768 he delivered one to Chappe, who, having observed the Venus transit of 1761 in Siberia, was then leaving to observe the transit of 1769 at the tip of Baja California. More important, Berthoud delivered two others into the hands of a young naval officer, Charles-Pierre d'Eveux de Fleurieu, who, with Pingré, was to give them an extensive transatlantic test that would include a stop at Santo Domingo for Pingré to view the transit of Venus. The almost yearlong voyage of the Isis held out great hope for Berthoud's clocks.[62]

This voyage was a product of a new initiative in the naval ministry associated with the duc de Choiseul's 1766 decision to turn those affairs, in which his own ideas had generated much opposition among the rouge , or noble officers of the navy, over to his cousin, the duc de Praslin. Abandoning the more radical projects entertained by his predecessor, Praslin simply reorganized such institutions as the Gardes-Marines and the Académie de Marine while undertaking to encourage the maritime revival of France through careful appointments and selected expeditions.[63]

For 1769 the Académie des Sciences renewed its 1767 Meslay subject with the offer of a double prize. Le Roy's submissions obtained that reward after again being put to a sea test in which Jean Dominique Cassini, the fourth member of that dynasty, served as the scientific observer.[64] Another good performance set the stage for a head-to-head competition between the clocks of Le Roy and those of Berthoud. The result, in 1771-1772, was a several-


month transatlantic voyage of the frigate La Flore . On board to deal with the clocks were Pingré and Jean-Charles le chevalier de Borda, a product of training in the famous military engineering school at Mézières but brought into the navy by Praslin and one of the many new members, along with such people as Lalande, named to the Académie de Marine in its 1769 reorganization.[65] Owing to an accident that befell the Le Roy clocks, a strict comparison did not result. Rather, the examiners simply concluded that marine clocks merited the confidence of navigators.[66]

One further confrontation between Le Roy and Berthoud failed to materialize. When the Académie des Sciences decided to reoffer a double Meslay prize for 1773 for the same subject as 1769, Berthoud, who had by then been named horloger mécanicien de la marine , declined to submit any work from his hand because of his status as official provider of marine clocks. Le Roy, however, did. He must have considered his winning somewhat hollow, though, for he shortly thereafter abandoned his work on marine timekeepers. He was subsequently given an annual pension to compensate him for the expenses of his research, but, apparently bitter over Berthoud's title, he did not pursue his investigations.

One may conveniently close off these considerations with the comment that, regardless of which man may have had more right on his side in this squabble, the modern marine chronometer, according to Gould's classic study, was derived far more from these French workers than from Harrison.[67] The same claim cannot be made about the competing lunar-distance technique for determining longitude at sea, even though Lacaille's work was a kind of watershed in revitalizing that approach. Still, the French efforts in this direction even after Maskelyne deserve at least some mention.

That Englishman's demonstration of the practicability of "lunars" with the first tables received from Mayer was greatly improved by what he was able to do with a second and superior set sent in 1763 by Mayer's widow.[68] That


compilation, indeed, became the basis upon which Maskelyne began the publication of the Nautical Almanac in 1766. The French were quick to recognize the usefulness of that publication. The Académie de Marine immediately pronounced itself in favor of lunar distances and, desiring that French seamen should have an equivalent guide, published tables and instructions to that end in 1772. At about the same time it undertook to translate the Almanac into French every year and to publish it one month later than its appearance in English. Moreover, as might be expected, the Connaissance des temps was enlisted in the same cause. Lalande, who had read memoirs suggesting that the approach could be expanded upon by adding distances between the moon and both Saturn and Venus, undertook to incorporate the distances listed in the Almanac —but not his own proposed distances—into his astronomical journal beginning with the issue for 1774.

Actually, Lalande had concerned himself with spreading the use of "lunars" even before Maskelyne began his annual almanac. Thus in 1764 he again advocated the technique in his famous text, L'Astronomie , while there then emerged from the Collège Royal one Pierre-Antoine Véron, whom he had carefully trained in its application.[69] Véron, in turn, imparted his knowledge to the French navy in the person of Charles-François-Phillippe de Charnières, upon whom hinged its subsequent development. In 1767, Charnières published a memoir describing his training expedition with Véron and both the advantages and the relative ease of the "lunars" approach.[70] When Lalande later listed this work in his Bibliographie astronomique he commented that Véron, in this voyage, had repaid to France "everything that the chair of astronomy had cost since its foundation."[71] Charnières brought out two further works, in 1768 and 1772, which dealt with "lunars" generally but also included descriptions of an instrument, adapted from Bouguer's heliometer, that he considered more appropriate than English octants for observing distances at sea.[72] The idea for this mégamètre, as he called the device, had


been given him by Véron, but it seems never to have been used by any others. Such was not the case with the reflecting circle, an instrument originally conceived by Mayer in the early 1750s but subjected to considerable improvement by Borda in the mid-1770s.[73] We shall return to that device shortly, but first we must conclude this account of longitude determination.

The technique of lunar distances was important in the first major French penetration of the Pacific Ocean. Véron, after all, accompanied Louis-Antoine, comte de Bougainville, on his circumnavigation of the globe between 1766 and 1769.[74] Bougainville was an important personage in the shift of focus of French expeditions after the Seven Years' War, a conflict that had stripped France of its overseas empire except for the small toeholds that Choiseul had been able to maintain with a view toward resuming the struggle at some future time. Bougainville, who, as Montcalm's aide, had had to negotiate the surrender of Quebec, was anxious to play some role in a French resurgence. His first idea was to plant a colony in the Malouines (Falkland Islands), which he did, at his own expense, early in 1764. Challenged by both the English and the Spanish, he subsequently negotiated the placing of that settlement under the sovereignty of the latter. That was accomplished in the early stages of a far more extensive venture—for as a consolation to Bougainville, Praslin granted him the right to undertake a voyage around the world during the course of which he could seek new areas to exploit in the vast reaches of the Pacific.

Thanks to the voyage of Gonneville, the French could claim some sort of a basis, however tenuous, for a right to such—or, at least, to lands associated with the supposed southern continent. That had been done, in fact, in 1738 when Lozier Bouvet had persuaded the French East India Company to commission him to follow the old captain's route for the discovery of lands which would be ideally suited both as a supply stop for company ships bound for India as well as for trade with South America.[75] Although


he did not find Gonneville's Land, he encountered a great deal of ice—then thought to be an indication that land was near—and discovered, on New Year's Day 1739, a cape that he believed to be attached to the southern continent. His desire to pursue that beginning with a far more ambitious expedition found no favor with the East India Company, however, and the dot of land in the South Atlantic that has come to bear the name of Bouvet Island quickly receded into relative obscurity.

The entire subject of the antipodal continent—whether Gonneville's Land, Bouvet's cape, or something else—began to become a significant element in European thought when Maupertuis, in 1752, called Frederick the Great's attention to the unexplored parts of the Southern Hemisphere in a Lettre sur le progrès des sciences . That work inspired the famous Histoire of the Président de Brosses that has been briefly but admirably described by Glyndwr Williams.[76] More than any other single work, de Brosses's Histoire replaced American exoticism, which had been in the process of becoming jaded in any event, with "the oceanic mirage, or more exactly the mirage of southern lands."[77]

This is not the place to consider the literary outcomes of that new orientation. Suffice it to say here that Bougainville's account of Tahiti as an earthly paradise was, quite naturally, a big element of that new orientation—as well, of course, as his bringing back of a Tahitian to Paris. Thanks to his many discussions with the latter, Bougainville himself came to recognize some of the social problems that existed in his Nouvelle-Cythère, but that did not prevent such philosophes as Diderot from undertaking, in his supplement to Bougainville's Voyage , to make it into a state of nature where, according to the prevailing theory derived from Condillac, man could be perfected through wise laws, education, and all the other tools so dear to the eighteenth-century Enlightenment.

Tahiti was the high point of Bougainville's voyage (Figure 3.3). He continued the well-worn westward route


Figure 3.3.
"Bougainville abordant à Taiti (îles Marquises)" from Léon Guérin,
 Les navigateurs français: historie des navigations, découvertes
 et colonisations françaises (Paris, 1846), facing p. 448.

thereafter, recognizing the Samoan Islands without stopping there, coming across the New Hebrides and guessing them to be the terra australis discovered by Quiros in 1606, avoiding the Great Barrier Reef, seeing various Solomon islands, and then entering the channel separating Nouvelle-Bretagne from Nouvelle-Irelande. There he found two excellent harbors, which he named Choiseul and Praslin, but found also native hostility and little provisioning. The latter points made it necessary for him to be provisioned by the Dutch in Molucca.

This entire course was, naturally, charted on a map which was not really very accurate. The more detailed maps of such harbors as Choiseul and Praslin were much better, however. And, in fact, Véron's more accurate determination of the position of several islands—accomplished, incidentally, with the aid of his mégamètre—was one of the basic contributions of the venture. Curiously, Bougainville, who was usually careful to point out the discrepancies


between his own "dead-reckoned" figures and those of Véron, states that the latter were arrived at by means of the method of horary angles rather than that of lunar distances.[78]

Bougainville returned to France in 1769—the year when, as we have seen, several English and French scientists were voyaging to observe the transit of Venus. To those names already mentioned, one must now add another of particular importance to this series. This, of course, is Captain James Cook, the publicized reason for whose voyage to Tahiti was to observe that phenomenon. His secret orders to search for the southern continent were not revealed until one hundred and sixty years later.[79]

For our purposes the significance of Cook's voyage was its generation of French responses. There were four of these between 1769 and 1773. Two of them need not really detain us. The voyages of Jean François de Surville and Marc-Joseph Marion-Dufresne were, after all, largely commercial ventures launched by the East India Company and stimulated in part by the vigor that Pierre Poivre, Praslin's appointment to the position of Intendant of the Mascareines, had brought to that area in the second half of the 1760s.[80] Neither voyage carried significant scientists or scientific equipment. Nevertheless, Surville's voyage did help to establish the position of the Solomon Islands with more precision. Marion-Dufresne's, on the other hand, accomplished little more than a slight setback for the noble savage idea when, after having begun as an effort to return Bougainville's Tahitian to his homeland, it ended in providing a human dinner for the fierce Maoris of New Zealand.

The two voyages of Yves-Joseph de Kerguelen-Tremerec deserve slightly more consideration even though they never entered into the Pacific per se. The first of his expeditions left France in May 1771.[81] On board as its astronomer was Alexis Rochon, a native of Brest, a seasoned voyager and chartmaker, and a recent addition to the reorganized Académie de Marine. Unfortunately for


Kerguelen, he had a falling-out with the astronomer and his positioning of the island he found in the southern Indian Ocean early in 1772—which he subsequently presented as Gonneville's Land found—was egregiously bad. Rochon, incidentally, had in the meantime been denied the right to sail with Marion-Dufresne and had, instead, given himself over to some exploring on his own, especially of Madagascar.[82] One interesting outcome of those travels was that, having advocated an improvement in Bouguer's heliometer, he now found and brought back to France some rock crystal with which he subsequently constructed a prismatic eyepiece for use on such instruments.[83]

As to Kerguelen's second voyage, to which he persuaded a rather reluctant French government, he was more fortunate in scientific aid. His astronomer was Joseph Lepaute d'Agelet, a rising Lalande student who had been placed in Lacaille's former observatory by that mentor, who also now provided him with an aide in the person of an even younger student named Mersay.[84] Though the expedition itself was largely a fiasco, the astronomers did manage to correct the earlier positioning of Kerguelen Island.[85]

The disappointing results of all these voyages and the American War of Independence brought about a hiatus in the launching of further French expeditions. Cook, of course, was very busy with his third voyage and, interestingly, was untouched by the war since French ships were specifically instructed to leave him alone.

The return of peace initiated a resumption of French activities in the Pacific. Indeed, they were now brought to a new level—in fact to a kind of climax—in the expedition of two ships, the Boussole and the Astrolabe , that left Brest on 1 August 1785 and were scheduled to return there four years later after circumnavigating the earth. They were under the command of Jean-François Galoup de Lapérouse, who had distinguished himself in American waters during the war and was now rewarded with the chance to sail in Cook's wake. The outcome is well known because the expedition—whose major geographical gift to pos-


terity was the exploration of the northeast Pacific, especially the seas around China and Japan—owes its fame in part to its ill fate, for it vanished in the South Pacific.[86] It is probably equally true to say, however, that its renown has stemmed from its characterization as a great scientific expedition.[87]

Some fifteen years ago I undertook to demonstrate that this characterization is misleading insofar as the primary motive for the voyage was a set of political and economic considerations growing out of a continuing competition for empire between England and France.[88] In fact, I showed that one of the clearest reasons for emphasizing the expedition's scientific missions was the hope that this would encourage favorable reception of the frigates in essentially foreign parts and waters—that they would be looked upon as had the ships of Cook earlier. That deception, incidentally, did not delude the English or even their recently independent American cousins. Although I do not now wish to disavow this interpretation, which, in fact, has since come to be the most widely held view,[89] I should insist upon the very real scientific aims and contributions of this undertaking.

Each of the ships carried several scientists as well as the tools of their trade. For our purposes I need mention only the astronomers. One of them, on the Boussole with Lapérouse, was the d'Agelet who had accompanied Kerguelen's second voyage. The other—like d'Agelet a professor of mathematics at the Ecole Militaire in Paris—was Louis Monge, younger brother of the more famous Gaspard, inventor of descriptive geometry at Mézières. Since he soon left the expedition when illness forced him to return to France, his astronomical function was assumed by Paul-Antoine de Langle, the expedition's second-in-command, director of the Académie de Marine, and a competent observer. The fact that such could be said of many French naval officers at this time might be considered an index of the general improvement of that branch and, more specifically, of the spread of astronomical knowledge there.


The most important works that these men engaged in were, for our purposes, the collection of pendulum observations made in a wide variety of latitudes with a view toward shedding further light on the shape of the earth—or at least bringing about better agreement between the figures for oblateness derived from arc measures and those obtained from gravity measurements. More important in the light of our earlier concerns, the expedition provided a setting for a thorough testing of the competing techniques of lunar distances and utilization of chronometers for determining longitude at sea. Furthermore, the expedition even provided, in that connection, a stage on which competing English and French devices could be set against one another, English octants against Borda's new reflecting circles, English chronometers versus Berthoud's timekeepers.

With that observation it seems well to recall by way of conclusion that a dual testing of longitude-determination techniques had been a project of the infant Académie des Sciences some one hundred and twenty years earlier. The specific attempt to carry it out had then failed as miserably as Lapérouse was to succeed brilliantly. The significant feature of the early effort, however, was not that it failed but that it represented an actualization of the new concept of the scientific expedition. The hundred and twenty years that separated Richer and Deshayes from d'Agelet and de Langle saw that technique employed to determine the size of the solar system and the shape of the earth as well as to develop methods for determining longitude and apply them on a worldwide scale. These were accomplishments that any nation could be proud of.

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