Serapis and the Duke of Athol, one an EastIndiaman, the other a frigate, have been burnt within these two last years, and many lives miserably destroyed, by drawing spirits out of a cask near a candle. It is high time to make it a general rule, that all the ship's store of spirits should be carried in bottles.

The misfortune by a stroke of lightning I have in my former writings endeavoured to show a method of guarding against, by a chain and pointed rod, extending, when run up, from above the top of the mast to the sea. These instruments are now made and sold at a reasonable price by Nairne & Co. in London, and there are several instances of success attending the use of them. They are kept in a box, and may be ran up and fixed in about five minutes, on the apparent approach of a thunder gust.

Of the meeting and shocking with other ships in the night I have known two instances in voyages between London and America. In one both ships arrived though much damaged, each reporting their belief that the other must have gone to the bottom. In the other, only one got to port; the other was never afterwards heard of. These instances happened many years ago, when the commerce between Europe and America was not a tenth part of what it is at present, ships of course thinner scattered, and the chance of meeting proportionably less. It has long been the practice to keep a look-out before in the channel, but at sea it has been neglected. If it is not at present thought worth while to take that precaution, it will in time become of more consequence; since the number of ships at sea is continually augmenting. A drum frequently beat, or a bell rung in a dark night, might help to prevent such accidents.

Islands of ice are frequently seen off the banks of Newfoundland, by ships going between North America and Europe. In the day time they are easily avoided, unless in a very thick fog. I remember two instances of ships running against them in the night. The first lost her bowspirit, but received little other dainage. The other struck where the warmth of the sea had wasted the ice next to it, and a part hung over above. This perhaps saved her, for she was under great way; but the upper part of the cliff taking her foretopmast, broke the shock, though it carried away the mast. She disengaged herself with some difficulty, and got safe into port; but the accident shows the possibility of other ships being wrecked and sunk by striking those vast masses of ice, of which I have seen one that we judged to be seventy feet high above the water, consequently eight times as much under water; and it is another reason for keeping a good look-out before, though far from any coast that may threaten danger.

der as savages have improved the art of sailing and rowing boats in several points beyond what we can pretend to. We have no sailingboats equal to the flying proas of the South Seas, no rowing or paddling-boat equal to that of the Greenlanders for swiftness and safety. The birch canoes of the North-American Indians have also some advantageous properties. They are so light that two men may carry one of them over land, which is capable of carrying a dozen upon the water; and in heeling they are not so subject to take in water as our boats, the sides of which are lowest in the middle where it is most likely to enter, this being highest in that part, as in figure 11.

The Chinese are an enlightened people, the most anciently civilized of any existing, and their arts are ancient, a presumption in their favour their method of rowing their boats differs from us, the oars being worked either two a-stern as we scull, or on the sides with the same kind of motion, being hung parallel to the keel on a rail, and always acting in the water, not perpendicular to the side as ours are, nor lifted out at every stroke, which is a loss of time, and the boat in the interval loses motion. They see our manner, and we theirs, but neither are disposed to learn of or copy the other.

To the several means of moving boats mentioned above, may be added the singular one lately exhibited at Javelle, on the Seine below Paris, where a clumsy boat was moved across that river in three minutes by rowing, not in the water, but in the air, that is, by whirling round a set of windmill vanes fixed to a horizontal axis, parallel to the keel, and placed at the head of the boat. The axis was bent into an elbow at the end, by the help of which it was turned by one man at a time. I saw the operation at a distance. The four vanes appeared to be about five feet long, and perhaps two and a half wide. The weather was calm. The labour appeared to be great for one man, as the two several times relieved each other. But the action upon the air by the oblique surfaces of the vanes must have been considerable, as the motion of the boat appeared tolerably quick going and returning; and she returned to the same place from whence she first set out, notwithstanding the current. This machine is since applied to the moving of air-balloons: an instrument similar may be contrived to move a boat by turning under water.

Several mechanical projectors have at dif ferent times proposed to give motion to boats, and even to ships, by means of circular rowing, or paddles placed on the circumference of wheels to be turned constantly on each side of the vessel; but this method, though frequently tried, has never been found so effectual as to encourage a continuance of the It is remarkable, that the people we consi-practice. I do not know that the reason has

down, and let the air pass out at E, which striking forcibly against the water abaft must push the boat forward. If there is added an air vessel F properly valved and placed, the force would continue to act while a fresh stroke is taken with the lever. The boatman might stand with his back to the stern, and putting his hands behind him, work the motion by taking hold of the cross bar at B, while another should steer; or if he had two such pumps, one on each side of the stern, with a lever for each hand, he might steer himself by working occasionally more or harder with either hand, as watermen now do with a pair of sculls. There is no position in which the body of a man can exert more strength than in pulling right upwards. To obtain more swift

hitherto been given. Perhaps it may be this, that great part of the force employed contributes little to the motion. For instance, (fig. 12) of the four paddles a, b, c, d, all under water, and turning to move a boat from X to Y, c has the most power, b nearly though not quite as much, their motion being nearly horizontal; but the force employed in moving a, is consumed in pressing almost downright upon the water till it comes to the place of b; and the force employed in moving d is consumed in lifting the water till d arrives at the surface; by which means much of the labour is lost. It is true, that by placing the wheels higher out of the water, this waste labour will be diminished in a calm, but where a sea runs, the wheels must unavoidably be often dipt deep in the waves, and the turn-ness, greasing the bottom of a vessel is someing of them thereby rendered very laborious to little purpose.

times used, and with good effect. I do not know that any writer has hitherto attempted Among the various means of giving motion to explain this. At first sight one would imato a boat, that of M. Bernoulli appears one of gine, that though the friction of a hard body, the most singular, which was to have fixed sliding on another hard body, and the resistin the boat a tube in the form of an L, the up- ance occasioned by that friction, might be diright part to have a funnel-kind of opening at minished by putting grease between them, yet top, convenient for filling the tube with wa- that a body sliding on a fluid, such as water, ter; which, descending and passing through should have no need of, nor receive any adthe lower horizontal part, and issuing in the vantage from such greasing. But the fact is middle of the stern, but under the surface of not disputed. And the reason perhaps may be the river, should push the boat forward. this-The particles of water have a mutual There is no doubt that the force of the de-attraction, called the attraction of adhesion. scending water would have a considerable effect, greater in proportion to the height from which it descended; but then it is to be considered, that every bucket full pumped or dipped up into the boat, from its side or through its bottom, must have its viz inertiæ overcome so as to receive the motion of the boat, before it can come to give motion by its descent; and that will be a deduction from the moving power. To remedy this, I would propose the addition of another such L pipe, and that they should stand back to back in the boat thus, figure 13, the forward one being worked as a pump, and sucking in the water at the head of the boat, would draw it forward while pushed in the same direction by the force at the stern. And after all it should be calculated whether the labour of pumping would be less than that of rowing. A fire-engine might possibly in some cases be applied in this operation with advantage. Perhaps this labour of raising water might be spared, and the whole force of a man applied to the moving of a boat by the use of air instead of water; suppose the boat constructed in this form, figure 14. A, a tube round or square, of two feet diameter, in which a So much respecting the motion of vessels. piston may move up and down. The piston to But we have sometimes occasion to stop their have valves in it, opening inwards, to admit motion; and if a bottom is near enough we air when the piston rises; and shutting, when can cast anchor: where there are no soundit is forced down by means of the lever B turn-ings, we have as yet no means to prevent ing on the centre C. The tube to have a driving in a storm, but by lying-to, which still valve D, to open when the piston is forced permits driving at the rate of about two miles

Water also adheres to wood, and to many other substances, but not to grease on the contrary they have a mutual repulsion, so that it is a question whether when oil is poured on water, they ever actually touch each other; for a drop of oil upon water, instead of sticking to the spot where it falls, as it would if it fell on a looking-glass, spreads instantly to an immense distance in a film extremely thin, which it could not easily do if it touched and rubbed or adhered even in a small degree to the surface of the water. Now the adhesive force of water to itself, and to other substances, may be estimated from the weight of it necessary to separate a drop, which adheres, while growing, till it has weight enough to force the separation and break the drop off. Let us suppose the drop to be the size of a pea, ther. there will be as many of these adhesions as there are drops of that size touching the bottom of a vessel, and these must be broken by the moving power, every step of her motion that amounts to a drop's breadth and there being no such adhesions to break between the water and a greased bottom, may occasion the difference.

its corners fastened to the ends of the four arms. Those ends are also to be stayed by ropes fastened to the stem or spar, so as to keep them short of being at right angles with it and to the end of one of the arms should be hung the small bag of ballast, and to the end of the opposite arm the empty keg. This, on being thrown into the sea, would immediately open; and when it had performed its function, and the storm over, a small rope from its other end being pulled on, would turn it, close it, and draw it easily home to the ship. This machine seems more simple in its operation, and more easily manageable than the first, and perhaps may be as effectual.*

he added, they are carried back by the current more than they are forwarded by the wind: and if the wind be good, the subtraction of 70 miles a day from their course is of some importance. I then observed it was a pity no notice was taken of this current upon the charts, and requested him to mark it out for me, which he readily complied with, adding directions for avoiding it in sailing from Europe to North America. I procured it to be engraved by order from the general post-office, on the old chart of the Atlantic, at Mount and Page's Tower-hill; and copies were sent down to Falmouth for the captains of the packets, who slighted it however; but it is since printed in France, of which edition I hereto annex a copy.*

Vessels are sometimes retarded, and sometimes forwarded in their voyages, by currents at sea, which are often not perceived. About This stream is probably generated by the the year 1769, or 70, there was an application great accumulation of water on the eastern made by the board of customs at Boston, to coast of America between the tropics, by the the lords of the treasury in London, complain- trade-winds which constantly blow there. It ing that the packets between Falmouth and is known that a large piece of water ten miles New York, were generally a fortnight longer broad and generally only three feet deep, has in their passages, than merchant-ships from by a strong wind had its waters driven to one London to Rhode-Island, and proposing that side and sustained so as to become six feet for the future they should be ordered to Rhode- deep, while the windward side was laid dry. Island instead of New York. Being then This may give some idea of the quantity concerned in the management of the Ameri- heaped up on the American coast, and the can post-office, I happened to be consulted on reason of its running down in a strong current the occasion; and it appearing strange to me through the islands into the bay of Mexico, that there should be such a difference between and from thence issuing through the gulf of two places, scarce a day's run asunder, espe- Florida, and proceeding along the coast to the cially when the merchant-ships are generally banks of Newfoundland, where it turns off todeeper laden, and more weakly manned than wards and runs down through the Western the packets, and had from London the whole Islands. Having since crossed this stream length of the river and channel to run before several times in passing between America and they left the land of England, while the Europe, I have been attentive to sundry cirpackets had only to go from Falmouth, I could cumstances relating to it, by which to know not but think the fact misunderstood or mis- when one is in it; and besides the gulph weed represented. There happened then to be in with which it is interspersed, I find that it is alLondon a Nantucket sea-captain of my ac- ways warmer than the sea on each side of it, quaintance, to whom I communicated the and that it does not sparkle in the night: Í affair. He told me he believed the fact might annex hereto the observations made with the be true; but the difference was owing to this, thermometer in two voyages, and possibly that the Rhode-Island captains were acquaint- may add a third. It will appear from them, ed with the gulf stream, which those of the that the thermometer may be an useful inEnglish packets were not. We are well ac-strument to a navigator, since currents comquainted with that stream, says he, because in our pursuit of whales, which keep near the sides of it, but are not to be met with in it, we run down along the sides, and frequently cross it to change our side: and in crossing it have sometimes met and spoke with those packets, who were in the middle of it, and stemming it. We have informed them that they were stemming a current, that was against them to the value of three miles an hour; and advised them to cross it and get out of it; but they were too wise to be counselled by simple Amecan fishermen. When the winds are but light,

Captain Truxton, on board whose ship this was written, has executed this proposed machine; he has given six arms to the umbrella, they are joined to the stem by iron hinges, and the canvas is double. He has taken it with him to China. February, 1786.

ing from the northward into southern seas, will probably be found colder than the water of those seas, as the currents from southern seas into northern are found warmer. And it is not to be wondered that so vast a body of deep warm water, several leagues wide, coming from between the tropics and issuing out of the gulph into the northern seas, should retain its warmth longer than the twenty or thirty days required to its passing the banks of Newfoundland. The quantity is too great, and it is too deep to be suddenly cooled by passing under a cooler air. The air immedi

*The map in this edition has beeen constructed so as to embrace in one view, the theory of the Gulf Stream and the theory of the migration of fish; some atten. tion has been paid also to Volney's suggestions on the subject of the Gulf Stream. See the plate.

ately over it, however, may receive so much warinth from it as to be rarefied and rise, being rendered lighter than the air on each side of the stream; hence those airs must flow in to supply the place of the rising warm air, and, meeting with each other, form those tornadoes and water-spouts frequently met with, and seen near and over the stream; and as the vapour from a cup of tea in a warm room and the breath of an animal in the same room, are hardly visible, but become sensible immediately when out in the cold air, so the vapour from the gulph stream, in warm latitudes is scarcely visible, but when it comes into the cool air from Newfoundland, it is condensed into the fogs, for which those parts are so remarkable.

The power of wind to raise water above its common level in the sea is known to us in America, by the high tides occasioned in all our sea-ports when a strong north-easter blows against the gulph stream.

pulse against the water, and probably thence shorten the voyage. Query, In returning does the contrary happen, and is her voyage thereby retarded and lengthened?"*

Would it not be a more secure method of planking ships, if, instead of thick single planks laid horizontally, we were to use planks of half the thickness, and lay them double and across each other as in figure 23? To me it seems that the difference of expense would not be considerable, and that the ship would be both tighter and stronger.

The securing of the ship is not the only necessary thing; securing the health of the sailors, a brave and valuable order of men, is likewise of great importance. With this view the methods so successfully practised by captain Cook in his long voyages cannot be too closely studied or carefully imitated. A full account of those methods is found in sir John Pringle's speech, when the medal of the Royal Society was given to that illustrious navigator. I am glad to see in his last voyage that he found the means effectual which I had proposed for preserving flour, bread, &c. from moisture and damage. They were found dry and good after being at sea four years. The method is described in my printed works, page 452, fifth edition. In the same, page 469, 470,† is proposed a means of allaying thirst in case of want of fresh water. This has since been practised in two instances with success. HapBut may there not be another cause, in-py if their hunger, when the other provisions dependent of winds and currents, why passages are generally shorter from America to Europe than from Europe to America? This question I formerly considered in the following short paper.

The conclusion from these remarks is, that a vessel from Europe to North America may shorten her passage by avoiding to stem the stream, in which the thermometer will be very useful; and a vessel from America to Europe may do the same by the same means of keeping in it. It may have often happened accidentally, that voyages have been shortened by these circumstances. It is well to have the command of them.

are consumed, could be relieved as commo. diously; and perhaps in time this may be found not impossible. An addition might be made to their present vegetable provision, by drying various roots in slices by the means of an oven. The sweet potatoe of America and Spain is excellent for this purpose. Other potatoes,

On board the Pennsylvania Packet, Captain with carrots, parsnips, and turnips, might be

Osborne..

At Sea, April 5, 1775.

"SUPPOSE a ship to make a voyage eastward from a place in lat. 40° north, to a place in lat. 50° north, distance in longitude 75 degrees.

"In sailing from 40 to 50, she goes from a place where a degree of longitude is about eight miles greater than in the place she is going to. A degree is equal to four minutes of time; consequently the ship in the harbour she leaves, partaking of the diurnal motion of the earth, moves two miles in a minute faster than when in the port she is going to; which is 120 miles in an hour.

"This motion in a ship and cargo is of great force, and if she could be lifted up suddenly from the harbour in which she lay quiet, and set down instantly in the latitude of the port she was bound to, though in a calm, that force contained in her would make her run a great way at a prodigious rate. This force must be lost gradually in her voyage, by gradual im

prepared and preserved in the same manner

With regard to make-shifts in cases of necessity, seamen are generally very ingenious themselves. They will excuse, however, the mention of two or three. If they happen in any circumstance, such as after shipwreck, taking to their boat, or the like, to want a compass, a fine sewing-needle laid on clear water in a cup will generally point to the north, most of them being a little magnetical, or may be made so by being strongly rubbed or hammered, lying in a north and south direction. If their needle is too heavy to float by itself, it may be supported by little pieces of cork or wood. A man who can swim, may be aided in a long traverse by his handkerchief formed into a kite, by two cross sticks extending to the four corners; which, being raised in the air when the wind is fair and fresh,

* Since this paper was read at the Society, an ingenious member, Mr. Patterson, has convinced the writer that the returning voyage would not, from this cause,

be retarded.

† See the Paper referred to in this volume, page 358.