principles of astronomy to geography. So remarkable was his early proficiency, that in 1676, at the age of twenty, he was sent to St. Helena to make a map of the stars in the southern hemisphere. While there, he observed a transit of Mercury across the disc of the sun. It occurred to him that this apparently trifling phenomenon might, by furnishing means for determining the sun's parallax, also furnish the elements for calculating the dimensions of the solar system. The transit of Venus seemed to him to afford still greater advantages, but that phenomenon occurs very rarely; one had taken place in 1639, the next would not happen till 1767. Halley earnestly exhorted astronomers who might then be alive, to observe that event. It was observed; and, so far as the subject of this sketch is concerned, it is interesting to remember that, in order to watch it, he undertook his first great voyage, which, as we shall see, so much enlarged our knowledge of the globe.

About the middle of the last century, the interests of commerce prompted some of the principal governments of Europe to fit out expeditions of considerable magnitude, partly for discovery, partly for the purpose of establishing colonies, and partly for the direct purpose of trade. The interests of science, too, began to be regarded as of sufficient consequence to be promoted at the public cost, and to warrant liberal expenditures. In 1764, Commodore Byron was sent on a voyage of discovery to the southern seas, and was absent nearly two years. One of his two ships was sheathed with copper, this being one of the first experiments for determining the value of that method of

preserving the bottoms of vessels from the attack of worms. After his return, Captain Wallis was sent out with the general design of prosecuting the discoveries still farther. He discovered the island Otaheite, or as it is now generally called, Tahiti. Of these voyages, however, commerce was, at least, as prominent a cause as science.

The first great expedition, fitted out mainly for scientific purposes, was that which sailed from Plymouth, August 26, 1768, under the command of Captain James Cook. The interest of the civilized world has ever clung to this distinguished navigator, in part, on account of his great professional merits, and in part, on account of his tragic death. This last circumstance has given him a hold upon the popular sympathies, which no other navigator ever obtained. About twenty years after the first voyage of Cook, the French commander, La Perouse, emulating his fame, and admiring his character, exceeded his model, perhaps, in the sad termination of his career. He sailed on a voyage of discovery, and his generation never heard of him again. For nearly forty years there was not the slightest clue to dispel the mystery which hung about his fate. But common minds need something tangible and palpable to arouse and retain their interest. In thousands of cottages in England and America were hung up rude prints of the "Death of Captain Cook;" while the mysterious fate of La Perouse, if we mistake not, produced, even among his own countrymen, its most lasting impression upon persons of comparatively high culture, and more likely to be affected by the gloomy obscurity of the unrevealing sea.

JAMES COOK was born in Yorkshire, in the year 1728. His father was a day-labourer to a respectable farmer, and, when his son was two years old, became an under steward upon an estate near the village of Great Ayton. James was kept at work upon the farm till he was thirteen, when he was permitted to attend school. He studied arithmetic and bookkeeping, and is said to have exhibited a good deal of talent at figures. When a few years older, he was apprenticed to a shopkeeper, in a small fishing town about ten miles from Whitby. Here he manifested good judgment and considerable skill in accounts, but his inclinations began to lead him very strongly to the sea. His master, willing to indulge him, gave up his indentures, and he soon engaged himself with the owners of some vessels employed in the coal trade. This navigation, carried on upon a coast, at some seasons of the year very dangerous, became from that circumstance a nursery of skilful seamen. As Cook was diligent in his new occupation, and gave satisfaction to his masters, they favoured him with opportunities of learning the various parts of his profession; and, in the course of a few years, he made voyages, not only upon the immediate coast, but to Liverpool and Dublin, and also to the Baltic.

In 1752, he was made mate of a vessel of 400 tons, and, in the next year, received the offer of being commander of the ship. This, however, he saw fit to decline. Impressments for the British navy were carried on, at this time, to a great extent; and either to avoid being taken contrary to his own consent, or for some other reason which does not appear, he entered

on board the Eagle, a man-of-war of sixty guns, under the command of Captain (afterwards Sir Hugh) Palliser. He served on board this vessel with so much distinction, that, by aid of his friends, and the strong recommendation of the captain, he was appointed master of the Mercury, a small vessel belonging to the squadron about to proceed to the attack upon Quebec. He soon joined the fleet in the St. Lawrence, and his talents and resolution were not long in making themselves perceived.

The fleet was expected to co-operate with the land forces under General Wolfe; but before this could be done, it was necessary to sound the river, so as to determine the channel. This was a difficult task, since it must be carried on in the face of a sagacious and watchful foe. It required a union of important qualities to enable one to perform the duty successfully. Cook was selected on the occasion, and entered upon the labour with accustomed resolution and skill. He carried on his operations in the night, and for some time was not perceived. At last he was discovered, and a large number of boats sent to cut him off. He fortunately became aware of the attempt in season to escape to the Island of Orleans. There was, however, little time for him to spare; since, just as he stepped on shore, the Indians in pursuit entered the stern of his boat, and took possession of it. His task, however, was accomplished, and he had the satisfaction of laying before the admiral a full and accurate survey of the channel.

After the conquest of Quebec, he was appointed to examine carefully the difficult parts of the river, which

was not then familiar to the English. He soon was transferred to the Northumberland, the flag ship of the commodore at Halifax, as master. Notwithstanding his success thus far, he felt his ignorance of mathematics, and applied himself in the midst of his other labours, to the study of Euclid's Elements of Geometry, and, having mastered them, to astronomy. He also devoted himself more particularly to the study of hydrography, in which he soon had an opportunity of exhibiting his skill, by a coast-survey of Newfoundland, which had lately fallen into the power of the English, and which began to be regarded, especially by its governor, Sir Hugh Palliser, as of great consequence for its fisheries. It was chiefly from this governor's recommendation, that Cook was appointed Marine Surveyor of Newfoundland and Labrador; and a schooner was placed under his command in order to enable him to perform his official duties. An account of a solar eclipse, observed in Newfoundland, which he transmitted to the Royal Society in 1766, and the longitude of the place as computed from it, gained him a good deal of credit for a knowledge of the scientific part of his profession. During some interval in his service on the northern coast of North America, he seems to have been upon the West India station, where he is mentioned as having been sent by the commanding officer, as a bearer of despatches to the Governor of Yucatan.

In the meantime, the year 1769 was approaching, in which was to take place that transit of Venus, which Dr. Halley had urged upon the attention of astronomers, as of so much consequence in its possible re