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DEPARTURE FROM CORUNNA.

CHAPTER II.

Voyage from Corunna to Teneriffe.

Departure from Corunna-Currents of the Atlantic Ocean-Marine Animals-Falling Stars-Swallows-Canary Islands-Lancerota-Fucus vitifolius-Causes of the Green Colour of Plants-La GraciosaStratified Basalt alternating with Marl-Hyalite-Quartz Sand— Remarks on the Distance at which Mountains are visible at Sea, and the Causes by which it is modified-Landing at Teneriffe.

THE wind having come round to the north-east, the Pizarro set sail on the afternoon of the 5th of June, 1799, and after working out of the narrow passage passed the Tower of Hercules, or lighthouse of Corunna, at half-past six. Towards evening the wind increased, and the sea ran high. They directed their course to the north-west, for the purpose of avoiding the English frigates which were cruising off the coast, and about nine spied the fire of a fishing-hut at Lisarga, which was the last object they beheld in the west of Europe. As they advanced, the light mingled itself with the stars which rose on the horizon. "Our eyes," says Humboldt, " remained involuntarily fixed upon it. Such impressions do not fade from the memory of those who have undertaken long voyages at an age when the emotions of the heart are in full force. How many recollections are awakened in the imagination by a luminous point which in the middle of a dark night, appearing at intervals above the agitated waves, marks the shore of one's native land!"

They were obliged to run under courses, and proceeded at the rate of ten knots, although the vessel was not a fast sailer. At six in the morning she rolled so much that the fore topgallant-mast was carried away. On the 7th they were in the latitude

EQUINOCTIAL CURRENT.

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of Cape Finisterre, the group of granitic rocks on which, named the Sierra de Torinona, is visible at sea to the distance of 59 miles. On the 8th, at sunset, they discovered from the mast-head an English convoy; and to avoid them they altered their course during the night. On the 9th they began to feel the effects of the great current which flows from the Azores towards the Straits of Gibraltar and the Canaries. Its direction was at first east-by-south; but nearer the inlet it became due east, and its force was such as, between 37° and 30° lat., sometimes to carry the vessel in twenty-four hours from 21 to 30 miles eastward.

Between the tropics, especially from the coast of Senegal to the Caribbean Sea, there is a stream that always flows from east to west, and which is named the Equinoctial Current. Its mean rapidity may be estimated at ten or eleven miles in twenty-four hours. This movement of the waters, which is also observed in the Pacific Ocean, having a direction contrary to that of the earth's rotation, is supposed to be connected with the latter only in so far as it changes into trade-winds those aerial currents from the poles, which, in the lower regions of the atmosphere, carry the cold air of the high latitudes towards the equator; and it is to the general impulse which these winds give to the surface of the ocean that the phenomenon in question is to be attributed. This current carries the waters of the Atlantic towards the Mosquito and Honduras coasts, from which they move northwards, and passing into the Gulf of Mexico follow the bendings of the shore from Vera Cruz to the mouth of the Rio del Norte, and from thence to the mouths of the Mississippi and the shoals at the southern extremity of Florida. After performing this circuit, it again directs itself northward, rushing with great impetuosity through the Straits of Bahama. At the end of these narrows, in the parallel of Cape Canaveral, the flow,

which rushes onward like a torrent, sometimes at the rate of five miles an hour, runs to the north-east. Its velocity diminishes and its breadth enlarges as it proceeds northward. Between Cape Biscayo and the Bank of Bahama the width is only 52 miles, while in 281° of lat. it is 59; and in the parallel of Charleston, opposite Cape Henlopen, it is from 138 to 173 miles, the rapidity being from three to five miles an hour where the stream is narrow, and only one mile as it advances towards the north. To the east of Boston and in the meridian of Halifax the current is nearly 276 miles broad. Here it suddenly turns towards the east; its western margin touching the extremity of the great bank of Newfoundland. From this to the Azores it continues to flow to the E. and E.S.E., still retaining part of the impulse which it had received nearly 1150 miles distant in the Straits of Florida. In the meridian of the Isles of Corvo and Flores, the most western of the Azores, it is not less than 552 miles in breadth. From the Azores it directs itself towards the Straits of Gibraltar, the island of Madeira, and the Canary Isles. To the south of Madeira we can distinctly follow its motion to the S.E. and S.S.E., bearing on the shores of Africa, between Capes Cantin and Bojador. Cape Blanco, which, next to Cape Verd, farther to the south, is the most prominent part of that coast, seems again to influence the direction of the stream; and in this parallel it mixes with the great equinoctial current as already described.

In this manner the waters of the Atlantic, between the parallels of 11° and 43°, are carried round in a continual whirlpool, which Humboldt calculates must take two years and ten months to perform its circuit of 13,118 miles. This great current is named the Gulf-stream. Off the coast of Newfoundland a branch separates from it, and runs from S. W. to N.E. towards the coasts of Europe.

From Corunna to 36° of latitude, our travellers had

MARINE ANIMALS-MEDUSE.

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scarcely seen any other animals, than terns (or seaswallows) and a few dolphins; but on the 11th June they entered a zone in which the whole sea was covered with a prodigious quantity of medusæ. The vessel was almost becalmed; but the molusca advanced towards the south-east with a rapidity equal to four times that of the current, and continued to pass nearly three-quarters of an hour, after which only a few scattered individuals were seen. Among these animals they recognised the Medusa aurita of Baster, the M. pelagica of Bosc, and a third approaching in its characters to the M. hysocella, which is distinguished by its yellowish-brown colour, and by having its tentacula longer than the body. Several of them were four inches in diameter, and the bright reflection from their bodies contrasted pleasantly with the azure tint of the sea.

On the morning of the 13th June, in lat. 34° 33', they observed large quantities of the Dagysa notata, of which several had been seen among the medusæ, and which consist of little transparent gelatinous sacs, extending to 14 lines, with a diameter of 2 or 3, and open at both ends. These cylinders are longitudinally agglutinated like the cells of a honeycomb, and form strings from six to eight inches in length. They observed, after it became dark, that none of the three species of medusa which they had collected emitted light unless they were slightly shaken. When a very irritable individual is placed on a tin plate, and the latter is struck with a piece of metal, the vibrations of the tin are sufficient to make the animal shine. Sometimes, on galvanizing medusæ, the phosphorescence appears at the moment when the chain closes, although the exciters are not in direct contact with the body of the subject. The fingers, after touching it, remain luminous for two or three minutes. Wood, on being rubbed with a medusa, becomes luminous, and after the phosphorescence has ceased, it may be rekindled by passing C

the dry hand over it; but when the light is a second time extinguished it cannot be reproduced.

Between the island of Madeira and the coast of Africa they were struck by the prodigious quantity of falling stars, which continued to increase as they advanced southward. These meteors, Humboldt remarks, are more common and more luminous in certain regions of the earth than in others. He has nowhere seen them more frequent than in the vicinity of the volcanoes of Quito and in that part of the South Sea which washes the shores of Guatimala. According to the observations of Benzenberg and Brandes, many falling stars noticed in Europe were only 63,950 yards, or a little more than 36 miles high; and one was measured, the elevation of which did not exceed 29,843 yards, or about 17 miles. In warm climates, and especially between the tropics, they often leave behind them a train which remains luminous for twelve or fifteen seconds. At other times they seem to burst, and separate into a number of sparks. They are generally much lower than in the north of Europe. These meteors can be observed only when the sky is clear; and perhaps none has ever been seen beneath a cloud. According to the observations of M. Arago, they usually follow the same course for several hours; and in this case their direction is that of the wind.

When the voyagers were 138 miles to the east of Madeira, a common swallow (Hirundo rustica) perched on the topsail-yard, and was caught. What could induce a bird, asks our traveller, to fly so far at this season, and in calm weather? In the expedition of Entrecasteaux, a swallow was also seen at the distance of 207 miles off Cape Blanco; but this happened about the end of October, and M. Labillardiere imagined that it had newly arrived from Europe.

The Pizarro had been ordered to touch at Lancerota, one of the Canaries, to ascertain whether the