with an accuracy hitherto unknown, the difference between the longitudes of the observatories at Uraniburg and Paris.

In consequence of this successful experiment, MM. Picard and Delahire, both academicians, were immediately employed to examine and to correct the map of France by astronomical observations. In executing this task, they were obliged to contract France within much narrower boundaries than it was supposed, according to the maps of that time, to occupy. They reduced it above 1° of longitude along the western coast from Brittany to the Bay of Biscay, and in the same inanner they cut away about half a degree from the shores of Languedoc and Provence. These changes gave rise to a jest of Louis XIV., who, when complimenting the academicians on their return, told them "he was sorry to observe that their journey had cost him a large portion of his kingdom."

Cassini, in the mean time, laboured indefatigably in endeavouring to improve geography, by allying it strictly with astronomy. He drew, in 1696, a planisphere on the floor of the observatory at Paris, on which he marked thirty-nine positions determined by recent observations. He vehemently reproached the learned world with the defects of geography, which in the march of science still lingered considerably in the rear. Mapmakers paid no attention to the astronomical observations which were multiplied round them every day, and which, though far from exact, never deviated into such errors as those which were handed down traditionally from the ancients. By his desire Chazelles was sent to the Levant, to correct the map of the Mediterranean: his observations ascertained the difference in longitude between the shores of Palestine and the meridian of Paris. The map of the portion of the Mediterranean which lies to the west of this meridian was not corrected till 1720. It is remarkable that Peiresc, in 1635, had reduced the distance from Aleppo to Marseilles from 45° to 30°. But the learned did not universally accede to those improvements proposed by individuals of eminent abilities. While Newton taught the laws which regulate the movements of the earth among heavenly bodies, little care was taken to delineate its surface. Geography continually relapsed to the errors of antiquity, and needed, as Cassini loudly complained, a total reform.

William Delisle, the friend of Cassini, was the first who seriously set about the task of reconstructing the geographical edifice. He conceived his grand design when young, and applied himself to it with such uncommon ardour that he had finished the task at the age of twenty-five. In the year 1700 he published his map of the world, as well as separate maps of Europe, Asia, and Africa. In these he boldly departed from the examples of his predecessors, and made free use of the materials

which the improvements in astronomy had placed within his reach. The defects of geography in his age belonged to the original vice of its system, and not to any deficiency of materials: it had been already enriched, and in every way improved, by the industry of Sanson, the learning of Ortelius, and the cleverness of Mercator. But Sanson, though the first geographer of the seventeenth century, still remained far behind the astronomical discoveries of the time. He followed blindly the longitudes of Ptolemy, and his sons and grandsons after his death continued to reproduce his maps, without paying any attention to the observations that were daily increasing. The maps of Coronelli and others, notwithstanding their reputation, were inferior to those of Sanson. In order to improve geography it was necessary to combine the narratives of travellers with the results of astronomical observations. This had been partially and ineffectually attempted before by Riccioli, Hondius, and others. But these previous revolts of reason against authority do not diminish the glory redounding to Delisle, from the revolution which he effected in geography: for he proved himself to accord with both ancient and modern measures; he combined a greater mass of materials, and instead of confining his corrections to one quarter of the globe, he proceeded through the whole; hence he has a good right to be considered the creator of modern geography. Peter the Great, when in Paris, condescended to visit him, and to give him what information he possessed respecting the geography of Muscovy.

Delisle died in 1726, but he lived to see his disciple J. B. D'Anville attain such eminence in his favourite study, as promised to bring geography to a speedy perfection. The talents of D'Anville procured him, at the early age of twenty-two, the honour of being appointed the king's geographer. He was remarkable for a singular correctness of judgment, and fineness of penetration, which appeared almost instinctive. He proceeded much on conjecture, and yet he rarely erred. The researches of the learned, and the increased acquaintance made with the globe within the last century, both bear witness to the sagacity of his spirit. Italy, before his time, was enlarged in the maps far beyond its true dimensions, and extended from west to east, according to the ideas of the ancients. But he ventured to reduce it, having previously discovered the true measures of the ancients; and the geodesical operations of Benedict XIV. showed him to be correct. His boldness completed what the resolution of Delisle had begun.

If the glory of reforming the inveterate errors of geography belongs in a peculiar manner to the French nation, the English at least had the merit of affording the most important elements to the laborious task. The discoveries of Newton did not ter

minate merely in the improvement of astronomy; they communicated, of course, an impulse to every branch of knowledge at all connected with that science. But his disciple Halley exerted a more immediate influence on geography. This extraordinary man, like D'Anville, distinguished himself at a very early age by his remarkable proficiency in his favourite study. At the age of nineteen, he published a direct method of finding the aphelia and eccentricity of the planets. He was aware that astronomy depended on an extensive knowledge of the position of the stars, and expressed his zealous desire to observe the stars in the southern hemisphere. Charles II. favoured his zeal ; and in 1676, when Halley was only twenty years of age, he embarked for St. Helena, on this important mission. He remained there a year; and, during that time, from the fault of the climate, he had fixed the places of only 350 stars. Had he chosen the Cape of Good Hope he would have found a clearer sky, as well as a more southern position.

While Halley was at St. Helena he observed a transit of Mercury across the sun's disc. This kind of phenomenon had already attracted the notice of Gassendi, Horrox, and other great astronomers; but Halley was the first to see all the important consequences that might be derived from it. He perceived that it might serve to determine the parallax of the sun, whence again might be calculated the dimensions of the solar system. The passage of Venus across the sun, which is of more rare occurrence, seemed to him at the same time to offer superior advantages. He weighed attentively and arranged the methods and consequences of these observations; and, in a memoir published in 1716, he announced to the learned world that the transit of Venus would afford the means of calculating the distance of the earth from the sun with greater precision than had been yet expected. The last time this phenomenon had taken place was in 1639, and it was not to recur till 1767; a time to which Halley, who was born in 1656, could not hope to have his life prolonged; he therefore exhorted other astronomers to attend to his admonitions. His counsel has been obeyed, and his expectations fulfilled. Besides the advantages directly accruing to geography from the perfection of astronomical science, the observation of the transit of Venus, so warmly and prophetically urged by Halley, has a peculiar interest, inasmuch as it gave rise to the first voyage of Cook, which contributed so much to dispel the obscurity which hung over our knowledge of the globe.

But it is not merely by his remote influence on geographical exertions that Halley is entitled to our respectful notice; he figured prominently also as a navigator and hydrographer, and was among the first to lay the foundations of physical geogra

phy. His "Theory of Magnetic Variations," with his "History of the Monsoons, or the Periodical Trade Winds," having attracted the attention of the learned, the king gave him a vessel to examine the Atlantic, and to try how far his theory was conformable with experience. He embarked on this expedition in 1698, with a captain's commission; but as he had not been educated in the navy, he was viewed by his officers with jealousy and dislike, and the mutiny of his lieutenant compelled him to return soon after he had passed the line. He again put to sea, however, in 1699, and proceeded to the south till he met ice, in lat. 52°. In September, 1700, he returned, not having lost a man in the course of his voyage; a circumstance at that time of rare occurrence, and which can be attributed only to the care and humanity of the commander. His observations during both his voyages were found to be favourable to his theory of magnetic variations. Captain Halley was employed on his return to survey the Channel, and was soon after sent on a mission to the Adriatic and to Vienna. This extraordinary man died in 1742, at the age of eighty-six, retaining his faculties unclouded till the last. His long life was throughout devoted to the advancement of science: his habitual industry was equal to the activity of his mind. He was at once a strict reasoner and a bold speculator; he had no morbid fear of theories, nor was he ever weaned by his attachment to them from his love of truth. He knew from experience how much navigation depended on astronomy, and laboured hard to make the latter subservient to the purposes of the former. He attempted to improve the theory of lunar motions; and, though not perfectly successful, he did as much as could be expected from one man. What he commenced La Place has completed. These are the exertions for which navigation and geography are indebted to the genius of Halley; but his fame as an astronomer rests chiefly perhaps on his application of the Newtonian laws to the motions of comets, and on his calculations respecting the precession of the equi

noxes.

Having thus briefly sketched the progress of geography towards mathematical correctness, and its alliance with the kindred science of astronomy, it may, perhaps, illustrate still further the gradual dissipation of error, if we cast a passing glance at the last advocate for a great southern continent. Although there is nothing intrinsically absurd in the supposition that land extends for a great distance round the South Pole, yet the belief in the necessity of an antarctic continent, in order to establish the equilibrium of the earth, and the credulous and even disingenuous attempts to support this hypothesis by fragments of authors of imperfect authenticity, may safely be reckoned among positive errors. Alexander Dalrymple sailed to India,

1737, in the service of the company: he afterwards visited the eastern archipelago; and, while studying the history of those interesting countries, the trade or the possession of which was eagerly coveted by his employers, he contracted a strong partiality for geographical researches; but, with the information which he obtained from the earliest Spanish navigators, he also imbibed their credulity, and at length firmly believed in the existence of a southern continent teeming with wealth and abundance. In compensation for his services in the East, he was appointed, on his return home, hydrographer to the East India Company; and was afterwards named hydrographer to the Admiralty, when that office was first created, in 1795.

But previous to that period, in 1772, Dalrymple wrote to lord North, who was then prime minister, to inform him that he was about to embark on an expedition at his own expense to discover a southern continent, and hoped that government would allow him to retain for five years all the countries which he should discover in the southern Atlantic between the longitudes 0° and 60° west of Greenwich, on condition that this grant should comprehend only those lands or islands examined within five years, and of which plans should be delivered in. Lord North took no notice of this application until urged by repeated letters; but at length he gave Dalrymple an audience, in which, however, the latter complained that the conversation turned more on the politics of the East than on geographical discoveries: the minister eluded the demands of Dalrymple by urging the necessity of consulting his colleagues.

It is probable that, in the course of conversation, lord North was led to form an unfavourable estimate of Dalrymple's understanding, and was unwilling to risk the reputation of government by patronizing the schemes of a flighty enthusiastic projector. Dalrymple, however, was so sanguine in his hopes of finding a southern continent adapted for colonization, that he went to the trouble of composing a code of laws for his embryo republic: the general character of these is such as to justify the coldness he experienced from lord North. According to his scheme women were not to be debarred from public offices; but, in the exercise of public duties and political rights, were to be on an equal footing with the men. No one in his republic was to exercise the profession of the law for hire or fee, no pain of forfeiture of all his property and perpetual imprisonment. The public accounts were to be exposed to general inspection on every Sunday in all the churches. To prevent luxury, no coin was to be used but copper money. Bachelors and maidens were to be heavily taxed; the sums thus raised being to go to the support of orphans. Finally, no one was to be admitted into the colony who did not subscribe to this code of laws, and on