Page images
PDF
EPUB

Unity at Bantam in October, the president of the Dutch East India Company confiscated the vessel and her cargo, declaring Schouten and his companions to be unlawful traders, and bade them seek redress in Holland. Spilberg's ships were then about to sail on their homeward voyage, and several of the discomfited adventurers took passage by them. Le Maire died from vexation after they had been two weeks at sea; and Schouten reached Holland in July, 1617, having accomplished his journey round the world in two years and eighteen days, and failed to obtain redress for the injustice of which he had been the victim. His voyage affords an instance of sagacious thought finding its confirmation in experience.

Another Spanish expedition under the Nodals, accompanied by Dutch pilots, sailed in 1618, to verify Schouten's discoveries; it returned, after surveying the coasts of Terra del Fuego. And in 1623, the Nassau fleet, composed of eleven Dutch ships of war, arrived in the same latitudes; the commander, Jacques le Hermite, found that several passages existed by which the Pacific could be reached without doubling the Horn or passing through the Straits-a fact confirmed by the late surveying voyage of Captain King in the Beagle. One of Hermite's vessels went as high as 60°, and rounded the Cape without once seeing it.

66

Meantime Pedro Fernandez de Quiros, in a memorial to the viceroy of Peru, had requested permission to plough up the waters of the unknown sea, and to seek out the undiscovered lands around the antarctic pole, the centre of that hori

zon."

With De Quiros to the south

Still urge the way, if yet some continent
Stretch to its dusky pole, with nations spread,
Forests, and hills, and streams.

of those people, the knowledge of it was kept secret.

For some time this new discovery was supposed to be the great south land; and, in 1642, Van Diemen, the governor of Batavia, sent Tasman to make explorations. In this voyage the geography of the region was determined; the extreme southern portion of the land was sailed round, and named after the governor, and its disconnection with an Austral continent conclusively proved. Tasman afterwards discovered New Zealand; and, possessed with the ideas of the period, he imagined that this remote island stretched away, and united with the Staten Land of Schouten and Le Maire at Terra del Fuego, and hoped it was "part of the unknown south continent." As an acknowledgment of Tasman's services by the States-General, the large island was named New Holland.

Those daring sea-rovers, the Bucaneers, while pushing their lawless cruises, for greater part of the seventeenth century, wherever the hope of plunder led them, contributed materially, though indirectly, to extend the limits of geographical research. Dampier and Wafer were among the party who marched across the Isthmus of Panama; and embarking in several canoes which they had stolen, rowed out to sea, and made prize of a vessel lying at anchor. Emboldened by success, they attacked and took larger ships, and in these traversed the Pacific Ocean. One of their captures was turned adrift as useless, with seven hundred pigs of metal on board, which they supposed to be lead; afterwards, when they came to make bullets from a lump which they had kept, the lead proved to be silver. Desirous of reëntering the Atlantic, they stretched boldly to the southwards till they met with ice, and doubled Cape Horn; and inspired so much confidence by their resolute perseverance, that a voyage round South America came to be regarded with diminished apprehension. Dampier was afterwards appointed to the command of a vessel, fitted out by the government of William III., in which he made further discoveries in New Holland and other southern countries. The war which broke out between England and Spain in 1739 lcd to Anson's famous voyage, which, though in many respects unfortunate, widened the boundaries of geographical knowledge. The wreck of one of the squadron, the Wager, on the coast of Terra del Fuego, although it gave the survivors an intimate knowledge of the country, will always be remembered as a most melancholy incident in the annals of disaster. "Nothing can be imagined," says the historian of the expedition, more savage and gloomy than the whole aspect of this coast." In doubling Cape Horn, "we had a continual succession of such tempestuous weather as surprised the oldest and most experienced mariners on board, and obliged them to confess that what they had hitherto called storms were inconsiderable gales compared with the violence of these winds, which raised such short, and, at the same time, such In 1606, Torres saw another great land, now mountainous waves, as greatly surpassed in danger known as Australia, which, with some show of all seas known in any other part of the globe." probability, might have been the continent imag-And he laments that "the squadron would be ined by his companion. Within the next twenty-separated never to unite again, and that this day of five years, the north and west shores of that vast our passage would be the last cheerful day that island were surveyed by Dutch navigators, and the greatest part of us would ever live to enjoy." there is reason to believe that it had been visited Up to this period, and for some time afterwards, by the Spaniards and Portuguese nearly a century earlier, as it is laid down in maps drawn about the year 1550, which are preserved in the British Museum; but, in accordance with the jealous policy

The north, he shows, was known up to the 70th degree of latitude, while" of the south part is discovered to 55 degrees only, passing the Strait of Magalhaens; and to 35 degrees, in which is the Cape of Good Hope; or 40 degrees and a little more, to which ships go in doubling it. Now are wanting the rest which remain from these, and from this parallel and to the west, from a lower latitude, to 90 degrees, to know if it is land or water, or what part there is of both." It was supposed, from the voyages that had been made to the Philippines and other islands of the Pacific, that a great land existed towards the pole, "the antipodes to the greater part of Europe, Africa, and Asia, where from 20 degrees to 60 degrees, God has made men so useful." Quiros sailed from Lima in 1605 in company with Torres; he discovered twenty-three islands, among which his Sagittaria and Encarnacion are believed to be Tahiti and Pitcairn's Island. And so confident was he that a greater extent of land would be found, that, on his return, in his communication to Philip II., he declared," in the southern parts lies hid a quarter of the globe."

66

the idea of a great southern continent was still entertained: philosophers argued in favor of it, for without a mass of land at the antipodes to counterbalance the preponderance in the north, the in

equality of weight would cause the earth to rotate | strong collier ship, the Endeavour, was selected;

A French expedition went out shortly afterwards, commanded by the unfortunate Marion, who was eaten by the New Zealanders. One of his lieutenants, Kerguelen, discovered land in 50° 5' south in February, 1772, and hastened back to France with glowing accounts of an antarctic continent. This was the most southerly land then known in the Atlantic. Cook touched at it during his third voyage, in 1776, and called it Desolation Island; but it is generally known by the name of its first discoverer.

in the opposite direction! Among the maps pub- and in August, 1768, Cook sailed. Banks and Solished in "Purchas' Pilgrims" is one which lander were on board as naturalists. They were represents South America as terminating at the thirty-four days in beating round the Horn; and Strait of Magellan, by which it is separated from after observing the transit, steered for New Zealand, a huge continent, larger, apparently, than any and disproved Tasman's supposition as to the conother division of the world, and named Terra Aus- nection of those islands with the southern continent. tralis Incognita; and that which accompanies Dam- The eastern coast of New Holland was afterwards pier's narrative contains the same delineation, but surveyed, from the spot where the Dutch navigator in a less exaggerated form. Every newly-discov- left off, to Torres' Straits, an extent of more than ered island was supposed to be an outlying portion 2000 miles. Cook landed and took possession of of the antarctic land, until, one after the other, their the country, giving it the name of New South southern extremities were explored. After all-Wales, and returned to England in 1770, after an so difficult is it to give up a long cherished belief- absence of two years and eleven months. arguments were still adduced to show that the connection might exist in the shape of a chain of islands Africa and America were probably connected in that way, and these again with the Terra Incognita. The essential differences of natural phenomena, as observed in the north and in the south, were also matter for speculation, and not a little error was mixed up with the truth. Acosta's treatise affords numerous instances. "Many in Europe," he writes, "demand of what forme and fashion heaven is in the southerne part; for that there is no certaintie found in ancient books, who, although they grant there is a heaven on this other part of the world, yet come they not to any knowledge of the form thereof." Ice was met with in lower latitudes than in the north; the seasons were less genial; the climate of Staten Land and Terra del Fuego would bear no comparison with that of countries lying in a similar latitude in the opposite zone. One reason assigned for the difference was, that the sun remained eight days longer in the northern than in the southern hemisphere, and that the north was nearer to the sun during winter. These, with many other absurd notions, were, however, to disappear before the increasing intelligence of the period to which we are now approaching.

In 1764, Commodore Byron, who had been wrecked in the Wager, sailed with two armed vessels" to make discoveries of countries hitherto unknown;" for, as stated in his instructions, "there was reason to believe that lands or islands of great extent, hitherto unvisited by any European power, may be found in the Atlantic Ocean between the Cape of Good Hope and the Magellanic Strait, with in the latitudes convenient for navigation." This voyage lasted twenty-two months, without enlarging the limits of southern exploration. The expedition by Wallis and Carteret in the Dolphin and Swallow followed in 1766. The ships were four months in passing the straits; and, having been separated in a gale, did not meet again during the cruise. Carteret rediscovered Pitcairn's Island, and Wallis Tahiti. The latter was unable to account for the natives being somewhat acquainted with the use of iron, but the prior discovery by Quiros furnishes a sufficient explanation. Bougainville's second voyage was also undertaken at the same time.

We come now to the voyages of Captain Cook; these had a definite scientific object. Astronomers were desirous that the transit of Venus over the sun's disk, which took place in 1769, should be observed on the other side of the world as well as in Europe; the determination of some highly important astronomical questions depended on it. Wallis, who had just returned, recommended a bay in Tahiti as a suitable locality for the purpose. A

Although Cook had shown that New Zealand was not united to the Terra Australis Incognita, it was still thought that a continent would be found. An expedition to search for it was sanctioned by the government; and Cook went out a second time with two vessels, the Resolution and Adventure, the latter commanded by Captain Furneaux, who had held the post of lieutenant under Wallis. To make the voyage as complete as possible, a number of scientific men and skilled artists were attached to the vessels, and every means taken to promote the health of the crews. They sailed in July, 1772; and in January of the following year were in 67° 15′ south latitude, where further progress was stopped by ice, and for the first time the aurora australis was observed. After a run of 11,000 miles, without once seeing land, Cook anchored at New Zealand to refit, from whence he again advanced towards the antarctic pole, in such a direction as to take advantage of the currents setting from west to east. On the 29th January, 1774, when in latitude 71° 10' south, longitude 106° 54' west, a point far beyond all those previously attained, he was stopped once more by ice, extending, as he believed, to the pole; yet, from the number of birds flying about the ship, he judged there must be land behind the ice; and he "who had ambition not only to go further than any one had gone before, but as far as it was possible for man to go,' was compelled to renounce his hope of penetrating nearer to the south. He subsequently traversed the whole of the Southern Pacific, the first time the feat had ever been accomplished; rounded Cape Horn with "more calms than storms;" surveyed the islands of Terra del Fuego; and started on a high latitude to cross the South Atlantic in January, 1775. On the 14th land was seen; and on the 17th, the great navigator landed to take possession, although he did not think "that any one would ever be benefited by the discovery." He named it Isle of Georgia, and describes it as savage and horrible. The wild rocks raised their lofty summits till they were lost in the clouds, and the valleys lay covered with everlasting snow. Not a tree was to be seen, not a shrub even big enough to make a toothpick."

66

[ocr errors]

"Who would have thought," he adds, "that an island of no greater extent than this, situated between the latitude of 54° 55', should in the very

height of summer be in a manner wholly covered | etrated as far as 69 degrees-the first time that the many fathoms deep with frozen snow?" Although antarctic circle had been crossed since Cook's voyhe saw much ice, he concluded that a greater extent age. Powell and Palmer, two Englishmen, also of land was required for its formation than here made some explorations about this period. In seen, and he hoped to discover a continent. Yet 1822, an expedition sailed from the Downs, which he says, "I must confess the disappointment I now reminds one of the enterprises of former days in met with did not affect me much; for to judge of the small size of the vessels, a brig and cutter; the the bulk by the sample, it would not be worth the one 160 tons, the other 65. They were commanded discovery." by Weddell and Brisbane, and were provisioned for a sealing voyage of two years. In the first part of their cruise they proved the non-existence of the supposed continent connecting Sandwich Land and the South Shetlands; and on the 18th February, 1823, were in latitude 72° 24' where not a particle of ice was to be seen; and on the 20th, in‍ 74° 15′, 214 miles beyond Cook's furthest. Here, although the sea continued open, and Weddell believed that no more land lay to the south to prevent access to the pole, he judged it most prudent, from the lateness of the season, to return. On anchoring at South Georgia, in March, he describes the sight of that desolate land as a gladness to their eyes after their lengthened and daring cruise.

In this part of his cruise Cook had no intention of going higher than 60 degrees, unless induced to do so by real signs of land. On the 30th, when in latitude 59° 13′ 30′′ south islands were seen, which he called Sandwich Land and Southern Thule, "because it is the most southern land that has ever yet been discovered." The great navigator shrewdly conjectured that a greater expanse of land existed nearer the pole, and that it projected most towards the north in the region of the South Atlantic and Indian Oceans, as more ice was always found there than in the South Pacific. Yet he declared himself"bold enough to say that no man will ever venture further than I have done, and that the lands which lie to the south will never be explored Lands doomed by nature to perpetual frigidness; never to feel the warmth of the sun's rays; whose horrible and savage aspect I have not words to describe."

The trade to this island, which began soon after Cook's report concerning it was published, has shown how fallacious were his predictions. In the course of a few years, it furnished more than a Subsequent events have proved that in these re-million of seal-skins, and 20,000 tuns of oil to the spects Cook was simply mistaken. Not so in his London market; and Kerguelen Island has proved explorations. His determination of positions and not less profitable. Mr. Weddell states that "duraccuracy of surveys are beyond all praise; few per- ing the time these two islands have been resorted sons have rendered greater services to the science to for the purposes of trade, more than 2000 tons of geography. He was, besides, the first to prove of shipping, and from 200 to 300 seamen, have that remote expeditions did not necessarily involve been employed annually in the traffic." From the waste of life; for, on returning to England in 1775, South Shetlands, also, in 1821 and 1822, 940 tuns after a voyage of three years and eighteen days, he of oil and 320,000 seal-skins were obtained. brought back the whole of his crew in health, with the exception of four lost by casualties. After this, publishers left the Terra Australis Incognita out of their maps.

In 1829, the South Shetlands were visited by the Chanticleer surveying-ship; in common with all the other lands of the Antarctic Ocean, they were found to be volcanic; some of them rising to A contemporary of Cook's, Alexander Dalrym- a height of between 6000 and 7000 feet. Lieutenple, afterwards hydrographer to the Admiralty, had ant Kendal describes them as "the most dreary long entertained a belief in the existence of an ant- aspect of barrenness ever beheld." No vegetation arctic continent, and frequently importuned the gov-was to be seen except a few lichens; but penguins, ernment to send him out with an expedition to pintados, and sea-leopards, were numerous. The colonize the probable country. He drew up a sin- ship was moored in a small cove in Deception gular code of laws by which the settlement was to be governed; women were to have equal privileges with men; all lawyers were to be subjected to perpetual imprisonment; bachelors and maids to be taxed; none but copper money; and accounts of the government expenses to be submitted to the public every Sunday. Had this project been realized within the antarctic circle, Dalrymple would have proved himself a colonizer of no common order.

After Cook's second voyage, no further advance was made in antarctic exploration until within the first quarter of the present century. In 1818, Captain Smith, while on a course from Monte Video to Valparaiso, saw a long line of coast, as it appeared to him, in latitude 62°. He reported the fact to the commander of the Andromache, then lying in the port to which he was bound, who sent an officer to survey the land. It was found to consist of a group of twelve principal islands, surrounded by countless rocks and rocky islets, which are now known as the South Shetlands, of which Gerritz caught a glimpse in 1599. In 1820, Weddell discovered the South Orkneys; and in 1821, Belling hausen, a Russian in command of the Vostok, pen

The

Island for several weeks, and an observatory built
on the shore, while the boats were employed in
the survey. The volcanic force was still active;
150 jets of steam could be seen from the Chanticleer's
anchorage. Surveying in such latitudes is, as
Lieutenant Kendal says, "cheerless work.
fogs were so frequent, that for the first ten days
we saw neither sun nor star; and it was, withal,
so raw and cold, that I do not recollect having suf-
fered more at any time in the arctic regions, even
at the lowest range of the thermometer."

Within the twelve following years are comprised the greatest achievements in antarctic research; Messrs. Enderby sent out a brig and cutter, the Tula and Lively, under Captain Biscoe, on a sealing voyage, in July, 1830. In the course of December he discovered an island in latitude 58° 25', longitude 26° 55', which he describes as "terrific, being nothing more than a complete rock, covered with ice, snow, and heavy clouds, so that it was difficult to distinguish one from the other." In January, 1831, he crossed Cook's track of 1773, and found the field ice in precisely the position where that celebrated explorer had left it; signs of land had been for some time visible, and on the 27th a considerable extent of coast was seen in lat

66

itude 65° 57′, longitude 47° 20′ east. In the night an aurora australis appeared "at times rolling," to quote Biscoe's words, as it were, over our heads in the form of beautiful columns, then as suddenly changing like the fringe of a curtain, and again shooting across the hemisphere like a serpent; frequently appearing not many yards above our heads, and decidedly within our atmosphere. It was by much the most magnificent phenomenon of the kind that I ever witnessed; and although the vessel was in considerable danger, running with a smart breeze, and much beset, the people could scarcely be kept from looking at the heavens instead of attending to the course.

[ocr errors]

Great efforts were made to reach the land, which lies on the antarctic circle, but the opposition of ice and currents was too powerful to be overcome. The health of the crew suffered from cold and exposure; and in April, while on the passage to Van Diemen's land, two men died, and the others were so weak, that, with the exception of the three officers, only one man and a boy were able to do duty. Undeterred by these casualties, Biscoe sailed again for the south in January, 1832, taking a southeasterly course, which, in the following month, in latitude 67° 1', longitude 71° 48' west, brought him to an island, the westernmost of a chain lying off a high main coast, now known as Graham's Land. He landed on the 21st February, and took possession in the name of his majesty, William IV. From this group, sometimes called Biscoe's Range, the discoverer touched at the South Shetlands, where he narrowly escaped shipwreck, and sailed for St. Catherine's, in Brazil, on which route the Lively was lost on one of the Falkland Islands. His voyage is remarkable as having comprised the circumnavigation of the south pole, and two cruises within the antarctic circle, as well as for the new lands which it brought to light. It affords another instructive instance of what may be accomplished by proper skill and courage with comparatively small means.

Another sealing expedition, a schooner and cutter in charge of Captain Balleny, was sent out by Messrs. Enderby in July, 1838. This was also successful in discovering land, a group of five islands, now called Balleny Isles, one of which rises with a splendid peak 15,000 feet above the sea-level. The vessels encountered much severe weather; and, on the 24th March, at midnight, during the return voyage, the cutter burned a blue light, which was answered from the schooner; but the heavy sea prevented communication. The next morning the little cutter was nowhere to be seen: she had perished with all her crew; and it was not without much difficulty that Balleny saved his vessel from a similar fate, and reached London in September, 1839.

In 1837, the French government sent out an expedition under Rear-Admiral D'Urville, an eminent explorer, who had already made three voyages ound the world. Two corvettes, the Astrolabe and élée, sailed from Toulon, and, by the end of the year, had followed Weddell's track in the antarctic seas until they were stopped by the ice between the 63d and 64th parallels. On three occasions an entrance was forced into it, but they were driven back each time, and forced to return. Louis Philippe's Land, however, was discovered, and some positions of the shores beyond Brandsfield Straits determined. After a lengthened cruise in Polynesia and the Indian Archipelago, D'Urville resolved to make another attempt to get to the

south, and touched at Hobart Town in a distressed condition, having lost three officers and thirteen men by dysentery. He sailed January 1, 1840, his special aim being to approach or reach the magnetic or terrestrial pole. The terrestrial moridian from Hobart Town to the pole coincides in a remarkable degree with the magnetic meridian, and, by steering on the former, D'Urville hoped to arrive at both the poles he was searching for by the same route. On the 21st he was surrounded by numerous ice islands, and saw a lofty line of coast covered with snow stretching from south-west to north-west, apparently without limit. With some difficulty a landing was effected, and possession taken in the name of France; it was called La Terre Adélie, after the wife of the discoverer. Two days afterwards, the vessels were separated by a terrific storm; they, however, weathered through, and met again on the 28th in an open sea towards the north, from whence they steered a south-westerly course to complete a series of magnetic observations-keeping a look-out for land in that direction. On this route, a ship was seen, which afterwards proved to be the Porpoise, one of the American squadron; the vessels passed without communicating; and in February, 1840, D'Urville returned to Hobart Town. The subsequent fate of this persevering navigator was truly melancholy; after having escaped all the dangers of a sailor's life during thirty years, he was burnt to death, with his wife and son, in the railway train between Paris and Versailles in 1842.

The United States' Exploring Expedition, the first that ever left that country for a scientific purpose, sailed in August, 1838. It comprised two sloops of war, the Vincennes and Peacock, the brig Porpoise, a store-ship, and two tenders. With respect to researches in the antarctic seas, Lieutenant Wilkes, the commander, was instructed to follow, as others had previously done, Weddell's track, and afterwards to explore as far as Cook's ne plus ultra, neglecting no opportunity of pushing to the south as might be compatible with the safety of the vessels. The Porpoise and Seagull tender sailed from Orange Harbor, on the west of Terra del Fuego, in February, 1839, for the first southern cruise, and explored in the vicinity of the South Shetlands. The Peacock and Flying-Fish followed, and penetrated as far as 70 degrees, when the approach of winter compelled their return. Off Cape Horn the Seagull separated from her consort, and was never afterwards heard of. The second cruise was made from Sydney with four of the ships; they sailed December 29, two days before D'Urville. Lieutenant Wilkes chose the meridian of Macquarie Island, designing, after a long stretch to the south, to turn westward, and beat round the circle to Enderby Land, and make a dash towards the pole whenever practicable. On the 16th January, in latitude 66 degrees, he landed on what was taken for an island, but which subsequent researches gave reason to suppose was a floating mass of ice. To make the exploration as effective as possible, the ships separated. They were, however, so ill adapted for navigation among ice, that although great exertions were used to widen the search, one after another they were compelled to abandon the enterprise, after having incurred extreme distress and danger. The Vincennes was the last to return; on the 30th January, Lieutenant Wilkes entered a bay, which he named Piner's Bay, in latitude 66° 45', and designated the country as the antarctic continent. The accumulations of floating

ice prevented his reaching the shore, and he was
then unaware that this was the Adélie Land of
D'Urville. The French admiral had landed there
a week previously, and taken possession. The
American squadron returned to the United States
in June, 1842.

The last and most memorable voyage to the south is that by Captain (now Sir James) Ross, whose labors in arctic research will be well remembered. Its scientific results were highly important, and it settled the question of a terra australis; such a land may now find a place in maps; the dreams of theorists are verified. This voyage more immediately originated in a recommendation by the British Association, in 1838, a period when the desirability of establishing the phenomena of terrestrial magnetism was strongly felt. tories were to be erected in different latitudes and Observain different zones of the earth, and much importance was attached to the filling up of the deficiencies of our knowledge of terrestrial magnetism" in the high southern latitudes between the meridians of New Holland and Cape Horn." The laws which regulated the movement of the needle were supposed to be extremely simple, operating in cycles, dependent on climatic or other and unknown causes. The simplicity, however, was apparent only; on investigation, the effects proved to be most complex, and the causes altogether unapproachable. Formerly, the variation alone was the phenomenon which received attention; now the dip and intensity were to be taken account of; and this, by a little contrivance, could be done at sea almost as well as on land. The inconstant nature of the phenomena had also to be considered, their relations to each other, their times and changes, and other incidents-all were essential in researches into the cause and effect of magnetism.

According to the report, so little was known of the magnetic lines of direction in the antarctic seas, "that the true position of the south magnetic pole could scarcely even be conjectured from the data already known;" and it would be of high importance to determine whether the magnetic phenomena observed during the voyage were simultaneous with similar phenomena in Europe or other parts of the world. On these points Sir James Ross' instructions were express and explicit; he was to notice in the South Atlantic the point where he crossed the curve or line of least magnetic intensity; to ascertain the depth of the ocean whenever practicable, and the temperature and specific gravity of the water at different distances below the surface; the strength and direction of currents and tides; periodical movement of the barometer; comparative brightness of stars; refraction, both terrestrial and celestial; and to swing pendulums in special localities, whereby to prove the figure of the earth. After refitting at Van Diemen's Land, he was to proceed direct to the southward, in order to determine the position of the magnetic pole, and even to attain to it if possible, which it is hoped will be one of the remarkable and creditable results of this expedition," one calculated to tion of the scientific men of all Europe.' engross the attenIt may, perhaps, assist towards a just appreciation of the results of this comprehensive voyage, to state briefly the three peculiarities of magnetic phenomena. There is within the polar circle of each hemisphere a point at which the dippingTeedle points straight downwards-this is the magnetic pole. Midway between these two points, a

66

66

9

line or curve may be traced all round the globe, on which the dipping-needle remains perfectly horizontal; this, through the greater part of its course, varies but slightly from a great circle whose plane is inclined about 12 degrees from the terrestrial equator; and, by analogy, it has been called the the compass-needle takes a direction in different magnetic equator. Then, as is commonly known, latitudes at times more or less oblique to the geographical meridian. The vertical plane hereby produced is called the magnetic meridian, and the angle which it forms with the terrestrial meridian on any part of the earth is termed the declination' or variation of the needle. The amount is not constant in all seasons for the same place; and, in the course of a single day, slight periodical changes occur, dependent apparently on the sun's height place more slowly, at intervals of years; and naviabove the horizon. But the absolute changes take gators generally follow the compass, as though the local declination were always the same, correcting it, however, occasionally by astronomical observation. By this following of the compass the lines might be laid down; near the magnetic equator they are almost parallel or perpendicular to it, but departing from it, they assume a progressive contour or flexion, all finally converging and terminating in the two points where the dipping-needle becomes vertical. The third element of magnetic force is the law of its intensity at different places; this is indicated by oscillations, more or less rapid, of the respective needles, as measures of density rience teaches that the intensity increases generally are judged of by vibrations of a pendulum. Expefrom the equator to the poles; but the progress of the increase, whether of dip or variation, is not regular-inequalities appear; effects have been noted in some localities which have not been wita principal magnetic force attaching as a result to nessed in others. From this fact, the existence of the whole mass of the globe has been inferred, whose general effects are modified locally by secondary magnetic forces, having their centres of action distributed at slight depths below the surface of the earth, in portions or districts probably affected by perturbations of the interior equilibrium.

tons, and the Terror; the latter having been Two vessels were fitted out, the Erebus of 350 repaired after returning from Back's hazardous voyage towards Repulse Bay. Ross and Crozier in each ship. They left Chatham on the 16th were the commanders, with sixty-four persons September, 1839, and on the 5th of October were off the Lizard, the last point of England which they were to see for several years. "It is not easy,' says Sir J. Ross, "to describe the joy and lightheartedness we all felt as we passed the entrance of the Channel, bounding before a favorable breeze over the blue waves of the ocean, fairly embarked in the enterprise we had all so long desired to commence.

ganized and carried out; the measured height of Scientific labors were immediately orwaves in the Bay of Biscay was 36 feet; at Madeira the height of the mountain was determined; magnetic observations were taken, and repeated 20, "the hourly register of the height of the afterwards at the Cape de Verds. On November barometer, and the temperature of the air and surface of the ocean, was substituted for the threehourly observations hitherto recorded, chiefly for the purpose of marking the progress of barometric depression in approaching, and reascension in receding from, the equator; a phenomenon repre

« PreviousContinue »