Observations of the Warmth of the Sea-water, &c., by Fahrenheit's Thermometer, in crossing the Gulph Stream; with other remarks made on board the Pennsylvania Packet, captain Osborne, bound from London to Philadelphia, in April and May, 1775.

Observations of the warmth of the Sea-Water, &c., by Fahrenheit's Thermometer; with other remarks made on board the Reprisal, captain Wycks, bound from Philadelphia to France, in October and November, 1776.

August 29. No moon, yet very little light in tion that by the valves being both open when

the water.

30. Much gulph weed to-day.

31. Ditto.

September 1. Ditto.

2. A little more light in the water.

going down, and both shut when coming up, it would keep within it the water received at bottom. The upper valve performed its office well, but the under one did not shut quite close, so that much of the water was lost in hauling it up the ship's

-4. No gulph weed to-day. More light in side. As the water in the keg's passage upwards

the water.

- 5. Some gulph weed again.

could not enter at the top, it was concluded that what water remained in it was of that near the

6. Little light in the water. A very hard ground, and on trying this by the thermometer, it thunder-gust in the night.

7. Little gulph weed.

weed.

8. More light in the water.

Little gulph -9. Little gulph weed. Little light in the water last evening.

10. Saw some beds of rock-weed; and we were surprised to observe the water six degrees colder by the thermometer than the preceding noon. This day (10th) the thermometer still kept descending, and at five in the morning of the 11th, it was in water as low as 70, when we struck soundings. The same evening the pilot came on board, and we found our ship about five degrees of longitude ahead of the reckoning, which our captain accounted for by supposing our course to have been near the edge of the gulph stream, and thus an eddy current always in our favour. By the distance we ran from Sept. 9, in the evening, till we struck soundings, we must have been at the western edge of the gulph stream, and the change in the temperature of the water was probably owing to our suddenly passing from that current, into the waters of our own climate.

On the 14th of August the following experiment was made. The weather being perfectly calm, an empty bottle, corked very tight, was sent down twenty fathoms, and it was drawn up still empty. It was then sent down thirty-five fathoms, when the weight of the water having forced in the cork, it was drawn up full; the water it contained was immediately tried by the thermometer, and found to be 70, which was six degrees colder than at the surface: the lead and bottle were visible, but not very distinctly so, at the depth of twelve fathoms, but when only seven fathoms deep they were perfectly seen from the ship. This experiment was thus repeated Sept. 11, when we were in soundings of eighteen fathoms. A keg was previously prepared with a valve at each end, one opening inward, the other outward; this was sent to the bottom in expecta

was found to be at 58, which was twelve degrees colder than at the surface.

This last Journal was obligingly kept for me by Mr. J. Williams, my fellow-passenger in the London Packet, who made all the experiments with great exactness. [The late colonel Williams of the U. S. Engineers.]

The chart in this edition, was constructed with a

view to a more comprehensive idea of the course of the gulph stream. Volney suggests, that the earth deposited by the gulph stream S. E. of Newfoundland, has formed the great banks; and that the accumulation there, has given the stream a new or more eastwardly direction. The chart also serves to illustrate the long received ideas of the progress of the shoals of fish. May not the glutinous matter seen on the water, and which all persons who have been across the line must have noticed to be luminous at night, be another cause of the phenomena of fish shoals. May they not come in search of the food, which the matter seen on the

water in such abundance affords? The writer of this note has observed, that on entering the trade winds, the seamen have judged of the change of wind ap proaching, by the direction of the bonetta and other fish, which pass in shoals in the South Atlantic and South-eastern seas, in a direct opposition to the wind; and when not opposite to the prevailing wind, they conclude a change to be at hand from the direction towards which the fish go. The appearance of luminous floating matter at night is often followed by shoals of fish; the spawn or gluten, which the writer has had taken up in a bucket, has been often found as large as two inches diameter, and frequently induced an opinion that it was a species of maritime cocoon or egg of an animal. An inquiry into the periodical appearance of these luminous substances on voyages to the southward, and remarks on the usual direction of the shoals of bonetta and other fish, might perhaps lead to interesting discoveries; it might be assumed as a ques tion worthy of examination, whether the direction of shoals of fish is not towards those points from which periodical winds or currents move the waters; and that the shoals of fish which move from the north poles, by the British isles across the Atlantic, are led by their instincts in search of these periodical supplies of food; and if the deposits so made by the gulph stream on the banks of Newfoundland is not the true cause of the great abundance of fish found there.

W. D.

To Oliver Neale.

On the Art of Swimming.

I CANNOT be of opinion with you that it is too late in life for you to learn to swim. The river near the bottom of your garden affords a most convenient place for the purpose. And as your new employment requires your being often on the water, of which you have such a dread, I think you would do well to make the trial; nothing being so likely to remove those apprehensions as the consciousness of an ability to swim to the shore, in case of an accident, or of supporting yourself in the water till a boat could come to take you up.

I do not know how far corks or bladders may be useful in learning to swim, having never seen much trial of them. Possibly they may be of service in supporting the body while you are learning what is called the stroke, or that manner of drawing in and striking out the hands and feet that is necessary to produce progressive motion. But you will be no swimmer till you can place some confidence in the power of the water to support you; I would therefore advise the acquiring that confidence in the first place; especially as I have known several who, by a little of the practice necessary for that purpose, have insensibly acquired the stroke, taught as it were by nature.

The practice I mean is this. Choosing a place where the water deepens gradually, walk coolly into it till it is up to your breast, then turn round, your face to the shore, and throw an egg into the water between you and the shore. It will sink to the bottom, and be easily seen there, as your water is clear. It must lie in water so deep as that you cannot reach it to take it up but by diving for it. To encourage yourself in order to do this, reflect that your progress will be from deeper to shallower water, and that at any time you may, by bringing your legs under you, and standing on the bottom, raise your head far above the water. Then plunge under it with your eyes open, throwing yourself towards the egg, and endeavouring by the action of your hands and feet against the water to get forward till within reach of it. In this attempt you will find, that the water buoys you up against your inclination; that it is not so easy a thing to sink as you imagined; that you cannot but by active force get down to the egg. Thus you feel the power of the water to support you, and learn to confide in that power; while your endeavours to overcome it, and to reach the egg, teach you the manner of acting on the water with your feet and hands, which action is afterwards used in swimming to support your head higher above water, or to go forward through it.

I would the more earnestly press you to the trial of this method, because, though I think I

satisfied you that your body is lighter than water, and that you might float in it a long time with your mouth free for breathing, if you would put yourself in a proper posture, and would be still and forbear struggling; yet till you have obtained this experimental confidence in the water, I cannot depend on your having the necessary presence of mind to recollect that posture and directions I gave you relating to it. The surprise may put all out of your mind. For though we value ourselves on being reasonable knowing creatures, reason and knowledge seem on such occasions to be of little use to us; and the brutes to whom we allow scarce a glimmering of either, appear to have the advantage of us.

I will, however, take this opportunity of repeating those particulars to you, which I mentioned in our last conversation, as, by perusing them at your leisure, you may possibly imprint them so in your memory as on occasion to be of some use to you.

1. That though the legs, arms, and head of a human body, being solid parts, are specifically something heavier than fresh water, yet the trunk, particularly the upper part, from its hollowness, is so much lighter than water, as that the whole of the body taken together is too light to sink wholly under water, but some part will remain above, until the lungs become filled with water, which happens from drawing water into them instead of air, when a person in the fright attempts breathing while the mouth and nostrils are under water. 2. That the legs and arms are specifically lighter than salt water, and will be supported by it, so that a human body would not sink in salt water, though the lungs were filled as above, but from the greater specific gravity of the head.

3. That therefore a person throwing himself on his back in salt water, and extending his arms, may easily lie so as to keep his mouth and nostrils free for breathing; and by a small motion of his hands may prevent turning, if he should perceive any tendency to it.

4. That in fresh water, if a man throws himself on his back, near the surface, he cannot long continue in that situation but by proper action of his hands on the water. If he uses no such action, the legs and lower part of the body will gradually sink till he comes into an upright position, in which he will continue suspended, the hollow of the breast keeping the head uppermost.

5. But if, in this erect position, the head is kept upright above the shoulders, as when we stand on the ground, the immersion will, by the weight of that part of the head that is out of water, reach above the mouth and nostrils, perhaps a little above the eyes, so that a man cannot long remain suspended in water with his head in that position.

6. The body continuing suspended as be