A Voyage of Discovery and Research in the Southern and Antarctic Regions/Volume 1/Chapter 1
Nine Pin Rock, Trinidad. Page 24.
CHAPTER I.
VOYAGE
OF
H.M.S. EREBUS AND TERROR
TO THE
ANTARCTIC OCEAN,
1839–43.
CHAPTER I.
The fortification of the Erebus being at length 1839.complete, she was warped out of dock on the 15th Aug. 15.of August, and, by the united efforts of both ships' crews, her equipment proceeded rapidly.
Sept. 2.On the 2d of September, the Right Hon. the Earl Minto, Vice-Admiral Sir Charles Adam, and Rear-Admiral Sir William Parker, the three Senior Lords Commissioners of the Admiralty, inspected the Erebus, and were pleased to express their satisfaction at the complete manner in which she had been fitted for the intended service.
Sept. 16.On the 16th I received their lordships' final instructions, and on the 19th the Erebus and Terror moved down the river to the moorings off Gillingham. Here the remainder of our stores and provisions was taken on board, and observations for the determination of the effect produced on the compasses by the iron of the ship were obtained. This operation, so simple and desirable at all times, became more important and essential in ships destined to navigate the more interesting regions of magnetic power, and to penetrate to the highest attainable magnetic latitude.
The Commander in Chief, Sir Robert Waller Otway, and his family, from whom, during the period of our fitting out under his immediate command, we had experienced many instances of kind consideration and assistance, honoured our ships by a visit on the 24th. On the morning of the Sept. 25.25th Captain Superintendent Clavell and the pay clerks came on board, and paid the crews three months' advance, in addition to the wages then due to them; soon after noon the moorings were slipped, and we sailed down the river, followed by the Terror. As we passed Sheerness a pilot came on board, but not having sufficient depth of water over the flats, we were obliged to anchor near the buoy off the Mouse until the next morning, when, towed by her Majesty's steam vessel Hecate, we proceeded to Margate Roads, where we anchored at 2h. 20m. p.m. The Terror joined us the following evening, and many people from Margate visited the ships during their stay at this anchorage. We were here supplied with a bower anchor from the dock-yard at Deal, to replace a damaged or defective one that had broken whilst we were in the act of heaving it up, fortunately at a time that no harm could result from the gross negligence of those whose duty it was to ascertain the soundness of that on which, under different circumstances, the ship, and lives of all on board, might have mainly depended.
Sept. 30A prevalence of westerly wind detained us in Margate Roads until the evening of the 30th September. It suddenly shifted to the eastward at six p.m., when we weighed, and beat round the Foreland; before midnight, we hove to for a few minutes in the Downs, to discharge our pilot, and to enable the Terror to join company.
We made good way down Channel until after Oct. 3.noon of the 3d October, when, abreast of the Start Point, we encountered a strong south-westerly gale; but, being unwilling to lose more time by entering any of the Channel ports, we kept the sea, and were gratified to find our ships behave well throughout the gale, although much deeper laden than we considered desirable. During the night of the gale the Terror parted company; but, as our run to Madeira, the first appointed rendezvous, was so short a distance, we proceeded without delay on our voyage alone.
On the morning of the 5th we were off the Oct 5.Lizard, the last point of the coast of England seen by us, and from which therefore we took our departure. It is not easy to describe the joy and lightheartedness we all felt as we passed the entrance of the Channel, bounding before a favourable breeze over the blue waves of the ocean, fairly embarked in the enterprise we had all so long desired to commence, and freed from the anxious and tedious operations of our protracted but requisite preparation.
The daily, almost hourly, observations of various kinds, from which so large a measure of useful and important results were expected, were now reduced into a practical system, and immediately entered upon with eager zeal and diligence by the officers of the Expedition.
During our passage across the Bay of Biscay we had no favourable opportunity of determining the height of its waves, as we experienced no violent storm: we had, however, a very rough and awkward sea, occasioned by a strong south-westerly breeze, and mixing confusedly with the long rolling northwesterly swell peculiar to this bay. The highest waves we measured scarcely exceeded thirty-six feet from their base to their summit; the velocity of their motion and their distance apart could not be determined without the presence of another vessel.
We availed ourselves of every opportunity of trying for soundings, but without finding the bottom with from three to six hundred fathoms of line. The specific gravity of the water we found to be 1.0278 at the surface, and the same to the depth of three hundred fathoms, although it was from ten to fifteen degrees colder than at the surface. In lat. 48° 20′ N. and long. 8° 0′ W. we passed through one of those very remarkable luminous patches that have been frequently before observed. It was about sixty or seventy feet in diameter, and much brighter in the centre than at the edges. It consisted of aggregated myriads of animalculæ, which emit a beautiful phosphorescent light when agitated by the vessel passing through their mass.
In the evening of the 19th, having reached the Oct. 19.assigned position of the shoal called "the Eight Stones," we hove to, and tried for, but could not obtain, soundings with three hundred fathoms of line, adding another to the many proofs of the nonexistence of that supposed danger.
At daylight the next morning Madeira island Oct. 20. was seen, and we anchored in Funchal Roads in the afternoon. By the kind and prompt attention of Mr. Stothard, the English consul, we were enabled at once to commence the necessary observations for rating our chronometers, and for the magnetic desiderata of dip, variation, and intensity,—the principal objects of our visit to this delightful spot. Some uncertainty still existing as to the exact altitude of Pico Ruivo, the highest mountain of the island, above the level of the sea, a party of officers was despatched to its summit, with two mountain barometers, for the purpose of its determination: this service was entrusted to Lieutenants Wilmot and Lefroy of the Royal Artillery, and corresponding observations were made with the standard barometers of the Erebus and Terror, near high-water mark, by the officers of the ships.
The result of these operations gave, for the height of Pico Ruivo, 6097.08 or 6102.90 English feet, according as Gay Lussac's or Rudberg's measure be taken for the expansion of air by heat. The result is computed by Bessel's tables[1], in which the hygrometric state of the atmosphere at the two stations is taken into the account. This elevation is some hundred feet greater than the height which was assigned by Lt.-Colonel Sabine from barometrical observations made by the late Captain Clavering, R.N., and himself, in the winter of 1821–22. It is probable that this difference has been occasioned by the frequently practised deception of the guides: when fog conceals the highest peak from view, they halt at a station they call the "Homme à pied," which, under such circumstances, may be easily mistaken for the summit, having a steep descent on every side. By this artifice the guides save themselves and the travellers the trouble and fatigue of descending into a deep ravine, and of thence ascending the most toilsome portion of the journey to the peak.
Since this was written, the result of Lieutenant Wilkes's observations has been published in his Narrative of the United States' Exploring Expedition. His computations assign an elevation to Pico Ruivo above half-tide of six thousand two hundred and thirty-seven feet: a difference of nearly one hundred and forty feet from our observations, and much greater than we should expect from the perfect and accurate instruments employed 1839 on both occasions.
The details of our observations are given in the Appendix, together with a letter I have received on the subject from Colonel Sabine, as it contains a useful caution and suggestion on barometrical measures.
The pile of stones erected by Lieutenant Wilkes's officers was pointed out to our party by the guides; but the notice left there by the Americans of their visit had been removed by some persons last year, and used by them, as the guides informed our officers, to light their fire. We did not learn the names of those who had been guilty of this ungracious act.
The day was splendidly beautiful, and our officers obtained a most magnificent view from their elevated position, overlooking the whole of the island: a circumstance of but rare occurrence, owing to the almost constant mist which encompasses the higher parts of the mountain, occasioned by the condensation of the vapour with which the atmosphere of this island is so fully charged.
Oct. 22.On the evening of the 22d a remarkable phenomenon was witnessed by us from the anchorage. We observed a very faint appearance of a pale rose colour rising behind the hills, to the left of Loo island, and twenty degrees west of the polar star: it increased in brightness and extent, until in twenty minutes it attained the altitude of thirty-three degrees, and bearing from N.W. to N. by E. by compass. At 7h. 45m. p.m., when it had risen to forty-three degrees, the colour became generally more deeply red, but much fainter near the edges, and by a few minutes after eight entirely disappeared. At half-past nine the same portion of the heavens was again illumined in a similar manner. Two coruscations, of a paler colour and yellowish tinge, were at this time distinctly visible, radiating from the point of first appearance; they were what might be termed about one foot broad, and ten feet apart at the altitude of twenty-five degrees, where they blended with the other light. At half-past ten the whole gradually passed away.
The wind was N. by W.; the compass was not at all affected during its continuance; the stars were seen through it, and the moon, which was for some time behind a cloud, seemed to produce only a comparatively slight change, when she afterwards shone forth with great brilliancy.
Much anxiety was expressed by the inhabitants of the island at this unusual phenomenon: various and absurd were their conjectures as to the cause. The more prevalent were, either that a new volcano had burst forth, or that some very large vessel had been destroyed by fire. Both these suppositions were proved erroneous on the arrival of the Terror at 8 a.m. on the 24th. She was about two hundred miles to the northward of Madeira at the time of its occurrence, and the description given of it by Commander Crozier and the officers of that ship agreed so exactly with our own observations, that no doubt could remain of its identity.
From the circumstance of the Terror being so many miles nearer to it than we were, and from its being observed still to the northward of her, without any material difference in its altitude, there can be no doubt that its region must be considered far beyond the limits of our atmosphere; but I must leave it to those more conversant with these matters to assign its cause.
During our stay at this island we were much indebted to Mr. Stothard for the liberal hospitality with which he placed his residence in Funchal entirely at the service of Commander Crozier and myself, and for affording us every facility in there making our observations: and also to the friendship and kind attentions of Mr. Veitch, late Consul-general; particularly for the gratification and advantage we derived from inspecting with him his celebrated "Jardin" of the mountain, where he has successfully cultivated several kinds of the tea, and other Chinese plants. The garden, or tea plantation, contained three or four hundred shrubs, and all our party considered the infusion of some of the species which we tasted to have such an excellent flavour as, in our opinion, to justify his expectations of eventually making it an article of commercial importance; provided the cost of labour in its preparation would not here, as at Rio, be found an obstacle.
Oct. 31.Bananas, dates, figs, spices, and all the choice tropical fruits, grow abundantly in the gardens about the town: and the quantity of coffee raised in the island, and which is of a very good quality, is sufficient to supply the wants of the whole population.
Our magnetic and other observations were only just completed, when a strong westerly breeze and heavy south-westerly swell, attended with such indications as to the experienced islanders predicted a coming storm, obliged us hurriedly to depart at 4h. p.m. on the 31st. At daylight on the 2d of November we saw the lofty peak of Teneriffe, distant about sixty miles: our object being to land our letters, we steered for Santa Cruz, the chief town of the Canary Islands; but, baffled by calms and light winds, it was not until the evening of the 4th that we were enabled to accomplish our purpose, and to bear away for the Cape de Verd Islands.
Nov. 6.We got the N.E. trade wind on the 6th, in latitude 27° N., and passed the tropic of Cancer on the evening of the 8th. We met with large numbers of flying-fish, attended by their persecutors, the bonito and dolphin; and thus early on our voyage we began the collection of natural history, by preserving as many different kinds of these creatures as we could procure, and by means of towing nets and other devices, gathered numerous curious and entirely new species of animalculæ, which, like the grass of the meadows to land animals, constitute the foundation of marine animal subsistence; and by their emitting a phosphorescent light upon disturbance, render the path of the ship through the waters on a dark night surprisingly brilliant.
On the 13th St. Jago Island was seen, and the Nov. 13. next morning, at ten o'clock, we anchored in Port Praya.
By permission of the Governor we landed our tents and instruments on Quail Island, and our observations were immediately commenced. The island, being of volcanic origin, is by no means a desirable position for magnetic determinations; but we had by this time learned to place more reliance on those taken on board our ships than on any made on shore, even under the most favourable circumstances. Our observations were here confined to the rating of our chronometers, and the spot selected for this purpose is close to a small beach on the west side of the island, and quite convenient to the anchorage.
Some of our officers, whose time and duties admitted of their making excursions to a distance from the shore, described the country, particularly the valley of St. Domingo, where was the ancient capital of the islands, as far more beautiful and fertile than they could have supposed from the desolate aspect its coasts present. Not far from the town we saw a fine specimen of the giant tropical tree of Africa, the Baobab (Adansonia digitata): its short, pear-shaped trunk, not more than ten feet high, exceeded thirty-eight feet in circumference, and at this period its fruit was forming.
The heat was most oppressive, and the sickly season being scarcely over, I was glad to leave as soon as possible. A few days were sufficient to complete our observations, and procure a supply of live stock, fresh fruit, vegetables, and water; all of which, except water, are of excellent quality and moderate price.
Nov. 20.We sailed from Port Praya on the morning of the 20th, and on that day the hourly register of the height of the barometer, and the temperature of the air and surface of the ocean, was substituted for the three-hourly 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 represented as being of the greatest and most universal influence, as it is in fact no other than a direct measure of the moving force by which the great currents of the trade winds are produced; so that the measure of its amount and the laws of its geographical distribution lie at the root of the theory of these winds.
In lat. 8° N., and long. 26° W., we entered the Variables, as the space between the N.E. and S.E. trades is called: here violent gusts of wind and torrents of rain alternate with calms and light baffling breezes, which, with the suffocating heat of the electrically-charged atmosphere, render this part of the voyage both disagreeable and unhealthy, especially in a flush-decked vessel, where the necessity of keeping the hatchways covered prevents the free circulation of air.
As opportunities offered, experiments were made to determine the height of the plane of vapour, a desideratum of great meteorological importance, connected with all the most interesting questions regarding the distribution of aqueous vapour over the globe and the irrigation of the continents. The results of these experiments differed so widely from each other, owing chiefly to the great difficulty of any thing like exact determination in observations of this nature, and probably in some degree from an actual difference of its altitude, under various conditions of the atmosphere, ranging from one thousand two hundred to nearly three thousand feet, barely entitle them to be esteemed more than a rough approximation, giving an elevation of about two thousand feet as its mean height in the tropical regions.
On the 27th, the sky being very clear, the planet Nov. 27.Venus was seen near the zenith, notwithstanding the brightness of the meridian sun, and was an object of much admiration to us all. It enabled us to observe the higher stratum of clouds to be moving in an exactly opposite direction to that of the wind, a circumstance which is frequently recorded in our meteorological journal, both in the N.E. and S.E. trades, and has also been observed by former voyagers. Captain Basil Hall witnessed it from the summit of the Peak of Teneriffe; and Count Strzelecki, on ascending the volcanic mountain of Kirauea, in Owhyhee, reached, at 4,000 feet, an elevation above that of the trade wind, and experienced the influence of an opposite current of air, of a different hygrometric and thermometric condition; facts which tend in some degree to explain the means by which the equilibrium of the atmosphere under certain conditions is maintained in those regions. Count Strzelecki further informed me of the following seemingly anomalous circumstance,—that at the height of 6,000 feet he found the current of air blowing at right angles to both the lower strata, also of a different hygrometric and thermometric condition, but warmer than the interstratum.
Our approach to St. Paul's Rocks, for which we were steering, was indicated by the appearance of the sea-birds which inhabit them, and at nine the next morning their two higher points were seen like specks on the horizon, at a distance of three or four leagues: the lower and smaller rocks gradually rose into view on nearing them, but our ships having been carried during the night so far to leeward, by a strong westerly current which we found to prevail here, we could not fetch them until late in the evening.
Nov. 29.We landed early the next morning, but not without difficulty, owing to the surf and swell which broke through the several channels into the central basin. We found the steep north-eastern side of the cove the most practicable point, and near it we obtained our observations. These remarkable rocks, which lie in lat. 0° 56′ N. and long. 29° 20′ W., and more than five hundred miles distant from any continent, appear to have been raised from the bed of the ocean by volcanic agency, and not in any part exceeding seventy feet above its surface, present the form of an oblong crater, the longer axis lying in a N.E. and S.W. direction. Mr. Darwin, however, considers them not to be of igneous origin, and, in this particular, unlike all the other detached islands of the Atlantic.
The following geological remarks upon them are by Mr. McCormick, surgeon of the Erebus, who attended to that branch of natural knowledge:—
"Situated nearly on the equator, in latitude 0° 56′ N., and longitude 29° 20′ W.; they consist of a group of rocks, altogether scarcely exceeding half a mile in circumference. The four largest form a kind of bay on the N. W. side, in which there is a considerable swell, from the surf breaking heavily through the three channels by which these rocks are separated from each other. The highest rock is on the N.E. side of the bay, rather sharply peaked, seventy feet above the level of the sea. The next in height, and the most remarkable, from its uniform white colour, is sixty-one feet, and situated on the S.W. or opposite side. This rock is composed of a very hard kind of hornstone, readily affording sparks under a blow of the hammer, and coated over with a thin layer of calcareous matter, evidently produced from the excrement of the numerous birds which have selected this spot as a breeding-place.
"The Pelecanus Sula, and Sterna stolida, are the only species inhabiting these rocks, together with a fierce and active crab, which appears to be a destructive enemy to their eggs.
"Not a vestige of vegetation of any kind is to be found, excepting a solitary species of Conferva, scantily distributed on the rocks, near the surface of the sea, and with which the noddies and boobies build their nests.
"The hornstone rests upon a very singular-looking rock, of a white colour, and meagre earthy feel; adhering slightly to the tongue, resembling kaolin, or decomposed felspar, beautifully streaked with thin veins of what appears to be serpentine, hard and vitreous as glassy felspar.
"These are the two prevailing rocks, occurring in various states of decomposition; where they are exposed to the spray of the sea, in many places much honey-combed, and intersected by masses of conglomerate, and very curious veins, from half an inch to half a foot in diameter, formed of two thin black plates of rock, much hardened and brittle, with a ringing sound, bearing all the marks of having been subjected to intense heat: frequently the space between the plates, or sides of the veins, is filled by a deposit of carbonate of lime; in others, by a calcareous-looking substance, which does not effervesce with acids, while some are empty.
"At low water, the sea-face of the rocks presents a band of pale red, the work of the coral insects, 
against which the surf is continually breaking. These rocks having been considered remarkable, as not being of a volcanic nature, I made a full collection of specimens[2]; and although, certainly, no lava or igneous rocks have made their way to the surface, in evidence of their true origin, yet the whole group presents, at a single glance, the most striking effects of the agency by which they have been forced upwards. The confused mass is mingled together without the slightest approach to stratification; in many places, the altered appearance of the rocks, from the effects of heat, prove them to have been volcanic, differing from other volcanic islands in the Atlantic, only from the melted matter not having reached the surface, but remaining as it were capped by the bed of the ocean."
Our observations here gave for the magnetic dip 27° 8′ N., and the variation 13° 20′ W.
We judged it to be low water this afternoon at Nov. 29three o'clock, and to have fallen between five and six feet; but owing to the surf we were unable to determine these points with the desired accuracy. The annexed sketch by Mr. Dayman will serve to convey a good idea of the size and arrangement of these rocks.
One of our party, in attempting to wade across a narrow channel, was taken off his feet by a heavy wave, and was for some time in imminent peril. Frequently he regained the margin of the shore, and struggled to maintain his hold, but was as frequently carried back by the retiring wave; whilst, unable to afford him the least assistance, we could only look on from the opposite side with the most painful apprehensions of seeing him taken away by one of the numerous sharks that were playing about the cove: however, being an expert swimmer, he at length succeeded in crawling up the rocks, greatly weakened by his long-continued exertions, though fortunately without other injury than a few bruises.
As we pulled off to the ships in the afternoon, we were led to believe, from the discoloration of the water, that it is probably shallow to the distance of a quarter of a mile from the shore. During our absence soundings had been obtained with three hundred fathoms on a rocky ground, and some small black stones came up with the lead, the islets bearing then S. 57 E., distant two-thirds of a mile; but they failed to reach the bottom with five hundred fathoms, when they bore S. 67 E. at twice that distance, so that the ascent of the submarine mountain of which these peaks form the summit must be very steep.
Dec. 3.We crossed the equator about midnight, the 3d of December, in long. 30 W., and the ceremony of shaving those who had not done so before was perpetrated the next morning with as much amusement and good-natured fun as usual on such occasions. Some difference of opinion prevails as to the proper meridian in which to cross the line; but having to visit St. Paul's Rocks, we were obliged to run thus far to leeward, or I would have preferred the longitude of about 26° or 27° W., for the strong westerly current is liable to carry ships with a scant trade too near to the coast of Brazil.
This current we found to diminish in strength as we proceeded to the southward, and in the 8th or 9th degree of latitude it gives place to a feeble northerly set.
The Magellhanic clouds and the beautiful constellation of the Southern Cross now became apparent; and although in my estimation the latter is inferior in beauty to several of our northern constellations, yet marking, night after night, by its gradually increasing altitude in the heavens, our advance upon our course, and becoming henceforward the pole-star that was to guide us throughout our researches, even as we hoped, to the utmost navigable limits of the Antarctic Ocean, we could not behold it without sanguine anticipations of the future.
In this part of the tropics we observed large patches of the splendid Pyrosoma, exhibiting a beautiful pale silvery light as we sailed past them: when taken out of the water the light is discontinued, until on irritating any particular part of the creature it again shows itself at that point, and soon pervades the whole animal mass.
As we approached the magnetic equator, or Dec. 7.line of no dip, our observations relative to this interesting question were more frequent; and in order to secure a faithful record of those of each ship, as well as to detect the cause of any differences in either, it became our practice every day at 1 p.m. to communicate by signal the results of all that had been obtained up to that time. So much advantage was derived from this measure, that I would strongly recommend its adoption by any expedition that may be employed on a service of this nature. We had watched the progressive diminution of the dip of the needle, and steering a course as nearly south as the wind permitted, in order to cross the line of no dip at right angles, we found the change so rapid as to be ascertained with great precision; so much so that the signal for our being on the exact point of no dip, where the needles, being equally poised between the northern and southern magnetic systems, assumed a perfectly horizontal position, was being hoisted from both ships at the same instant of time. Nothing could be more satisfactory than the perfect accordance of our observations in a determination of so much importance: nor could it fail to be of more than ordinary interest to me to witness the needle thus affected; having some years previously, when at the north magnetic pole, seen it in a directly vertical position: nor was it unnatural, when we saw the south pole of the needle beginning to point below the horizon, to indulge the hope that ere long we might be permitted again to see it in a similar position at the south magnetic pole of the earth.
The regularity, as well as the rapidity, with which the alterations of dip occur, is also worthy of notice. At two hundred and eighty miles north of the magnetic equator, the dip was 9° 36′, showing about 2.05 minutes of change for every mile of latitude; at two hundred and ninety-two miles to the south, the dip was 9° 52′, or about 2.03 minutes for every mile of latitude. It is to be remembered that this large amount of change is limited to the region of the magnetic equator; near the poles, it requires an approach of about two miles to produce an alteration of a single minute of dip.
The geographical position of the magnetic equator where we crossed it was lat. 13° 45′ S, long. 30° 41′ W. Here we again felt the influence of a westerly current of nearly a mile an hour.
The next matter of "great and especial interest in a magnetic point of view," to which my attention was directed in the instructions drawn up for my guidance, at the request of the Lords Commissioners of the Admiralty, by the Committee of Physics of the Royal Society, was that of the situation of the point of minimum total intensity, or that point where the intensity is the least which occurs over the whole surface of the globe. It may be proper first to explain that, in passing from the north to the south magnetic hemisphere, there is upon every meridian a point at which the intensity, after having gradually diminished, again begins to increase as you advance to the higher magnetic latitudes.
These several points united form a circle round the earth similar to the magnetic equator, or circle of no dip, like it dividing its circumference into two nearly equal portions, and with which it was until lately erroneously considered to be identical. Upon this circle there is a spot where the intensity is at a minimum, now to be the particular object of our investigation, together with the direction of that circle, and the form and extent of the lines and ovals of isodynamic or equal intensity.
In order to accomplish these several objects, it became necessary to pursue a course widely different from that usually followed by vessels bound to St. Helena, and imposed upon us the tedious operation of beating up to that island against the trade wind, an experiment seldom, if ever, attempted, and in our dull-sailing ships could only be effected by the sacrifice of a considerable portion of time. As we stood Dec. 16.to the southward we crossed the circle, or equator of less intensity, in lat. 19° S. and long. 29° 15′ W., two hundred miles more to the northward than previous observations had led us to expect.
Dec. 17.On the morning of the 17th December, the island of Trinidad was seen; and at 7h. 30m. a.m. Commander Crozier and I, accompanied by several officers, left the ships. After pulling along the leeside of the island, we at length landed in a small cove, a short distance to the northward of the Nine Pin Rock, of Halley, the surf on all other parts being too great to admit of it without hazarding the destruction of our boats. The island is a mass of volcanic matter, and rises abruptly on its leeward side to an elevation of abont two thousand feet in some parts. The trap rocks of which it is composed assume most extraordinary shapes: the more remarkable of these are the Sugar Loaf Hill, near the southern, and the Nine Pin Rock, at the north-western part of the island. This latter projected to the height of eight hundred and fifty feet, almost perpendicularly from the sea, in the form of a beautifully proportioned column, is attached at its inner side to a ridge of hills two or three hundred feet high, which, like the mountains that present an insuperable barrier between the short beach of large rounded pebbles on which we landed, and the interior of the island, is chiefly composed of greenstone.
As a magnetic station, our observations here were utterly valueless, but the results may be useful by pointing out, in a striking manner, the great amount of error to which those made on shore are liable. Three dipping needles placed at only just sufficient distance apart to ensure their not influencing each other, indicated as much as three degrees difference of the dip, and all of them considerably less than that corresponding to the geographical position. To as large an amount also were the observations of variation vitiated by the local disturbing magnetic influence; whilst those taken on board our ships were perfectly free from these errors.
Horsburgh mentions that the island abounds with wild pigs and goats; one of the latter was seen. With the view to add somewhat to the stock of useful creatures, a cock and two hens were put on shore; they seemed greatly to enjoy the change, and, I have no doubt, in so unfrequented a situation, and so delightful a climate, will quickly increase in numbers. We returned to our ships at 7 p.m., and made all sail to the southward. Trinidad was still in sight the next morning, at a distance of nearly fifty miles, and might be seen still further under more favourable circumstances.
- ↑ Scientific Memoirs, vol. ii. art. xvi.
- ↑ A list of these specimens is given in the Appendix.