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reaching to the zenith, and passing over the moon's disk, encircling her with a faint halo of twenty degrees in diameter. It continued an nour, and although it was bright moonlight, the phenomenon was very distinct and beautiful.

On the 5th, the winds drew to the south-southeast, and we crossed the line, as we had intended, in longitude 17° W., which enabled us to pass over and examine the supposed locality of the Triton Bank, in longitude 17° 46' W., latitude 00° 32' 00" S. The current was found this day to be setting to the northeast, fifteen miles in the last twenty-four hours. This night the sea was extremely brilliant, showing in large luminous patches. The light proved to be occasioned by a large species of Pyrosoma, some of which were ten inches in length, and two inches in diameter. Many phosphorescent animalcula were taken, and some rips that were seen, exhibited long lines of brilliant light. Temperature of water 76.5°. Our dipping-needle on the equator gave 23° 30'. Hourly observations were made for forty-eight hours, to ascertain the oscillations of the barometer under the equator (for which see Appendix XVI.) The periods of oscillation were found to be as follows: the maxima at nine A. M. and nine P. M., and the minima at three A. M. and three P. M. The variation was 1 of an inch, and was found to be very regular, from latitude 3° 30' N., to 4° S.

We had now heavy deposits of dew, on several fine and cloudless evenings. Indeed the sun had scarcely set before the ship was quite wet with it. One of the essential requisites supposed necessary by Dr. Wells for a deposit of dew, was certainly wanting in this case, viz., that “the temperature of the body on which it was deposited, should be considerably lower than the surrounding air;”—the temperature of the air and ship having remained the same for several days at about 78°: all objects, hammock-cloths, spars, sails, and rigging, so far as could be ascertained, showed the same. And at the time when the dew was observed to be most copious, we had a fine breeze. It has generally been supposed that dew never falls off soundings. This at least is an old saying among seamen: but our observations are at variance with this notion; for, as far as every indication went, both by sounding and blue water, we certainly had no bottom.

The supposed position of the Triton Shoal was now passed over, and examined carefully in the same manner as heretofore described, sounding at the same time with two and three hundred fathoms of line. Nothing of the kind was perceived, nor was there any indication of soundings in the discoloration of the water, or any change in its temperature.

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We next sailed for a vigia laid down on the chart. On the 7th November at noon we were in longitude 18° 20' W., and latitude 3° 30' N. Here we first experienced the influence of the equatorial current, and found it setting west by north at the rate of half a mile per hour. This vigia was not seen. I then stood for Bouvet's Sandy Isle, or its reported position. We saw nothing of it whatever. I was very desirous of continuing my search farther to the west, from the report I had seen of various vessels having experienced shocks of earthquakes, and the belief having been entertained that shoals might have been formed by them. The equatorial current having been felt, I was aware that in getting farther to the west, I should lose the opportunity of examining the locality where that distinguished navigator, Admiral Krusenstern, supposed he saw a volcano. I therefore gave up proceeding farther to the westward in this latitude, and hauled up for its position. It was now the 9th of November; we had delightful weather; and moderate breezes from the south and east. An amusing circumstance occurred this night. In our course we passed very near a large sail, which from the night being dark, the officer of the deck of the Porpoise mistook for the Vincennes, although sailing on a different course. He immediately, agreeably to his orders, followed the vessel, and continued after her until morning, when, to his surprise, he discovered that it was a large Dutch ship. Fortunately, I had perceived the ship pass, and conjectured, when we found the Porpoise was not in sight at daylight, the nature of the mistake. I therefore retraced my steps, and in an hour or two we again came in sight of her, then tacked and proceeded on our course. On the next day, the time being very favourable, we hove-to, to get a deep-sea sounding with the wire line, and ran out one thousand six hundred fathoms of it. On reeling it up, the wire parted, and we lost nine hundred and sixty fathoms of line, with our sounding apparatus, including one of Six's self-registering thermometers. The wire was badly prepared and ill adapted to the purpose. On the 11th we found ourselves near the location of Krusenstern's supposed shoal, ran over the position in parallel lines, and satisfied ourselves of its non-existence. Having now examined all the localities which were designated in my instructions, I made all sail for Rio de Janeiro. We now found ourselves in the equatorial current, setting us west twenty-five miles in twenty-four hours. On the nights of the 11th, 12th, and 13th, we kept a watch for the periodical showers of stars. About thirty were seen in the mid-watch of the 13th, proceeding from the Pleiades, and shooting in a northerly direction. Our position was in latitude 6° 15' S., and longitude 24° 25' W. The Peacock, whose situation was about forty miles to the westward of us at the time, saw a number shooting from the constellations Orion and Leo. The equatorial current was now strongest, setting thirty miles in a day to the westward; the breeze had become very steady and strong; the upper current was found to correspond with the direction of the lower. Every day the wind was observed to freshen as the sun was coming to the meridian, and continued so until the afternoon, when it died away again, freshening after dark, and continuing until near daylight. On the 16th of November we passed the magnetic equator in latitude 13° 30' S., longitude 30° 18' W. The variation was found by careful observations to be 10° 30' W. We continued to pursue our course rapidly, experiencing the current setting more to the southward, and upwards of twenty miles a day. On the 22d we made Cape Frio; here we fell in with and boarded the ship Louisiana, in fifty days from New York, and were much gratified by getting letters and papers. The progressive temperature on the passage from the Cape de Verde Islands to Rio, was as follows: it rose until it reached its maximum in 9° 24' N., water 83.5°, whilst the air was at 81-6°; from thence to striking soundings, it decreased to 75°, and on soundings 69°. The soundings obtained off the cape were in fifty fathoms, ouze and shells, the water changing its colour to a deep green, and as we approached the harbour, to a dark olive. On the afternoon of the 23d of November, we took a light wind from the southeast, and with all sail set stood in for the magnificent harbour of Rio Janeiro. Our attention was drawn first to the high, fantastic, and abrupt peaks of Gavia, the Sugar Loaf, and Corcovado, on our left; whilst on our right, we had the bold point of Santa Cruz; then before us the city of San Sebastian, and the towns of San Domingo, with Praya Grande opposite, and the islands and fleet that lay between them decking this beautiful expanse of water. These objects, with the pinnacles of the Organ Mountains for a background, form such a scene that it would be difficult to point out in what manner it could be improved. The life and stir created by the number of vessels, boats, and steamers of various forms and of all sizes passing to and fro, give great animation to the whole. The mountains present a very peculiar appearance. Their tops and sides have a rounded or worn surface, destitute of verdure, with the exception of here and there a yellowish patch, produced by the Tillandsias, which in places cover the rocks. The abruptness of the Sugar Loaf Mountain, and those immediately behind Santa Cruz, strikes the spectator very forcibly. The shipping do not form as in other places a dense forest of masts. There being no wharves, they are obliged to lie at anchor, exhibiting their proportions and symmetry to great advantage. They are usually seen grouped together, with their different flags fiying, forming a picture that a painter would delight in. As we proceeded up the harbour, our own flag was seen to wave over that magnificent specimen of naval architecture, the Independence; and as we passed her, our bosoms beat to the tune of Hail Columbia, played by the band. There is a feeling of security on entering the harbour of Rio, that I have seldom experienced elsewhere, not even in our own waters. The mountains seem as it were to afford complete protection from the winds and ocean. We anchored near Enxados or Hospital Island, and found the Peacock had arrived here three days before us, and that she was proceeding with her repairs rapidly. The vessels being altogether unfit for the southern cruise, it became necessary to effect the requisite repairs as speedily as possible. While I could not but deprecate the loss of time and the shortening of the season for our southern operations, I felt it an imperative duty that I owed to those who were engaged with me on this service, not to suffer them to go among the many dangers of our southern cruise badly provided with the means to secure them against ordinary accidents, and to encounter the weather we must necessarily anticipate. On our arrival I was told it was the beginning of the hot season, and that rains usually prevailed during the coming months. This was unpleasant news, particularly as I was desirous, whilst making the necessary repairs on the vessels, to complete a set of astronomical observations, and to perform a series of experiments with the pendulums, &c. This information, however, I did not find to be correct, and from the examination of the meteorological tables (see Appendix XVII.) obligingly furnished me by John Gardner, Esq., an American gentleman residing at Rio, I am not disposed to credit this common saying. It therein appears that rain falls as often in other months as in December, and my experience during the time of our stay corresponds with these tables. The first fortnight we had occasional rains, but before we left the harbour our parties reported that the country was suffering from drought. Mr. Gardner has also obligingly favoured me with a table (see Appendix XVIII.) showing the monthly average of passages from the United States to Rio during eight years, from 1834 to 1841. The shortest passage occurred in the year 1835, and the longest in 1840. The former by a very fast vessel in twenty-nine days; the latter by an ordinary merchant-ship in ninety days. The Relief, our store-ship, had one hundred days in 1838 but this includes touching three days at the Cape de Verdes.

It will be seen that the average monthly passage does not vary but a few days throughout the whole eight years. The winter months are the most favourable, in consequence of the strong westerly winds that prevail in the North Atlantic at that season, and also to the prevalence of the northeast monsoons on the coast of Brazil.

Our observations would point out the necessity of dull-sailing vessels not crossing the equator to the westward of 20° of west longitude, where the equatorial current begins to be felt; but vessels that sail well, may cross it as far as 26° W., particularly when the northeast monsoons prevail in their full strength, and very much shorten their passage by such a course.

During the repairs, I endeavoured to employ my time and that of the officers and scientific gentlemen in as advantageous a manner as possible. We are indebted to the Hon. William Hunter, our charge d'affaires, and our consul, William Slacum, Esq., for many kindnesses and attentions received during our stay. Through their intercession, I obtained the use of the small island of Enxados, which was well adapted to our purposes. The instruments and stores were allowed to be landed there free of inspection, and every assistance we could desire was afforded us by the government and its officers. How different a policy and treatment from that pursued towards Captain Cook some seventy years before, under an ignorant and jealous colonial government

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