[5] "Before leaving Port Praya, Captain Cook invited the governor- general and the commandant to dinner, and we staid on board in order to act as interpreters on this occasion. The captain sent them his own boat; but when it came on shore the governor begged to be excused, because he was always affected with sickness on board any vessel, whether at sea or in harbour. The commandant promised to come, but having at first neglected to ask the governor's leave, the latter retired to take his siesta, (or afternoon's repose,) and no one ventured to disturb him."--G.F.
On the 19th, in the afternoon, one of the carpenter's mates fell overboard, and was drowned. He was over the side, fitting in one of the scuttles, from whence it is supposed he had fallen; for he was not seen till the very instant he sunk under the ship's stern, when our endeavours to save him were too late. This loss was sensibly felt during the voyage, as he was a sober man and a good workman. About noon the next day, the rain poured down upon us, not in drops but in streams. The wind, at the same time, was variable and squally, which obliged the people to attend the decks, so that few in the ships escaped a good soaking. We, however, benefited by it, as it gave us an opportunity of filling all our empty water-casks. This heavy rain at last brought on a dead calm, which continued twenty-four hours, when it was succeeded by a breeze from S.W. Betwixt this point and S. it continued for several days; and blew at times in squalls, attended with rain and hot sultry weather. The mercury in the thermometers at noon, kept generally from 79 to 82.[6]
[6] "The heavy rains entirely soaked the plumage of a poor swallow, which had accompanied us for several days past; it was obliged, therefore, to settle on the railing of the quarter-deck, and suffered itself to be caught. From the history of this bird, which was of the common species, we may deduce the circumstances that bring solitary land-birds a great way out to sea. It seems to be probable, that they begin with following a ship, from the time she leaves the land; that they are soon lost in the great ocean, and are thus obliged to continue close to the ship, as the only solid mass in this immense fluid expanse. If two or more ships are in company, it is also easy to account for the expression of meeting with land-birds at a great distance from land, because they may happen to follow some other ship from the shore, than that which carries the observer; thus they may escape observation for a day or two, or perhaps longer, and when noticed, are supposed to be met with at sea. However, great storms are sometimes known to have driven single birds, nay, vast flocks, out to sea, which are obliged to seek for rest on board of ships at considerable distances from any land. Captain Cook very obligingly communicated to me a fact which confirms the above assertion. "Being on board of a ship between Norway and England, he met with a violent storm, during which a flight of several hundred birds covered the whole rigging of the ship. Among numbers of small birds he observed several hawks, which lived very luxuriously by preying on those poor defenceless creatures."--G.F.
To record incidents such as these, will not seem unimportant or injudicious to any one who knows the philosophical value of facts in the formation of just theories.--E.
On the 27th, spoke with Captain Furneaux, who informed us that one of his petty officers was dead. At this time we had not one sick on board, although we had every thing of this kind to fear from the rain we had had, which is a great promoter of sickness in hot climates. To prevent this, and agreeable to some hints I had from Sir Hugh Palliser and from Captain Campbell, I took every necessary precaution by airing and drying the ship with fires made betwixt decks, smoaking, &c. and by obliging the people to air their bedding, wash and dry their clothes, whenever there was an opportunity. A neglect of these things causeth a disagreeable smell below, affects the air, and seldom fails to bring on sickness, but more especially in hot and wet weather.
We now began to see some of those birds which are said never to fly far from land; that is, man-of-war and tropic birds, gannets, &c. No land, however, that we knew of, could be nearer than eighty leagues.
On the 3Oth at noon, being in the latitude of 2° 35' N., longitude 7° 30' W., and the wind having veered to the east of south, we tacked and stretched to the S.W. In the latitude of 0° 52' N., longitude 9° 25' W., we had one calm day, which gave us an opportunity of trying the current in a boat. We found it set to the north one-third of a mile an hour. We had reason to expect this from the difference we frequently found between the observed latitude, and that given by the log; and Mr Kendal's watch shewed us that it set to the east also. This was fully confirmed by the lunar observations; when it appeared that we were 3° 0' more to the east than the common reckoning. At the time of trying the current, the mercury in the thermometer in the open air stood at 75-1/2; and when immerged in the surface of the sea, at 74; but when immerged eighty fathoms deep (where it remained fifteen minutes) when it came up, the mercury stood at 66.[7] At the same time we sounded, without out finding the bottom, with a line of two hundred and fifty fathoms.
[7] "This morning, 5th September, I let down a thermometer, suspended in the middle of a strong wooden case, of such a construction as to let the water pass freely through it in its descent, but which shut close the instant it began to be drawn up. By this means the thermometer was brought up in a body of water of the same heat with that it had been let down to. The results were as above."--W.
This opportunity may be used for introducing the following table and remarks, which are certainly deserving attention. "To ascertain the degree of warmth of the sea-water, at a certain depth, several experiments were made by us. The thermometer made use of, was of Fahrenheit's construction, made by Mr Ramsden, and furnished with an ivory scale; it was, on these occasions, always put into a cylindrical tin case, which had at each end a valve, admitting the water as long as the instrument was going down, and shutting while it was hauling up again. The annexed table will at once shew the result of the experiments.
| Degrees of Fahrenheit's | |Stay of |Time in|
| Thermometer. | |the |hauling|
|--------------------------| |Thermo- |the |
| |On the | |Depth |meter |Thermo-|
| In the |Surface |At a |in |in the |meter |
| Air. |of the |certain |Fathoms. |Deep. |up. |
Date |Latitude | |Sea. |Depth. | | | |
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1772
Sept. 5 00°52'N. 75° 74° 66° 85 F. 30' 27-1/2'
Sept.27. 24°44'S. 72-1/2 70° 68° 80 F. 15' 7'
Oct. 12. 34°48'S. 60° 59° 58° 100 F. 2O' 6'
Dec. 15. 55°00'S. 30-1/2° 30° 34° 100 F. 17' 5-1/2'
Dec. 23. 55°26'S 33° 32° 34-1/2° 100 F. 16' 6-1/2'
1773
Jan. 13. 61°00'S. 37° 33-1/2° 32° 100 F. 20' 7'
--------------------------------------------------------------------------From this table it appears, that under the Line and near the tropics, the water is cooler at a great depth than at its surface. In high latitudes, the air is cooler sometimes, sometimes very near upon a par, and sometimes warmer than the sea-water at the depth of about 100 fathoms, according as the preceding changes of the temperature of the air, or the direction and violence of the wind happen to fall out. For it is to be observed, that these experiments were always made when we had a calm, or at least very little wind; because in a gale of wind, we could not have been able to make them in a boat. Another probable cause of the difference in the temperature of the sea-water in the same high latitude, undoubtedly must be sought in the ice; in a sea covered with high and extensive ice islands, the water should be colder than in a sea which is at a great distance from any ice."--F.
This table is evidently too confined, and made up of too few elements, to justify almost any general inferences. The subject is certainly a curious one, and merits full investigation, but presents very considerable difficulties, as many circumstances, which are likely to modify the result, may escape notice during the experiments. It has been said, that as water is most dense at from 37 to 39 Fahrenheit, this may be presumed to be the mean temperature at the bottom of the sea; but such hypothetical deductions are, perhaps, entitled to little confidence. It may however be safely enough presumed, that the temperature of the sea is kept tolerably uniform on the well-known principle of statics, that the heavier columns of any fluid displace those that are lighter. The waters of the ocean, perhaps, are the great agent by which the average temperature of our globe is preserved almost entirely invariable. We shall have an opportunity, in the account of another voyage, to make some remarks on this subject, and to notice more exact experiments than those just now mentioned.--E.
The calm was succeeded by a light breeze at S.W., which kept veering by little and little to the south, and at last to the eastward of south, attended with clear serene weather. At length, on the 8th of September, we crossed the Line in the longitude of 8° W.; after which, the ceremony of ducking, &c., generally practised on this occasion, was not omitted.
The wind now veering more and more to the east, and blowing a gentle top- gallant gale, in eight days it carried us into the latitude 9° 30' S., longitude 18° W. The weather was pleasant; and we daily saw some of those birds which are looked upon as signs of the vicinity of land; such as boobies, man of war, tropic birds, and gannets. We supposed they came from the isle of St Matthew, or Ascension; which isles we must have passed at no great distance.
On the 27th, in the latitude of 25° 29', longitude 24° 54', we discovered a sail to the west standing after us. She was a snow; and the colours she shewed, either a Portuguese or St George's ensign, the distance being too great to distinguish the one from the other, and I did not choose to wait to get nearer, or to speak with her.