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ing and extensive knowledge in most sciences, waves in a storm by pouring oil into the sea would have more distinguished him, had he which he mentions, as well as the use made been placed in a more conspicuous point of oil by the divers; but the stilling a tempest of view, you will find, that he had heard of by throwing vinegar into the air had escaped your experiment on Derwent Lake, and has me. I think with your friend, that it has been thrown together what he could collect on of late too much the mode to slight the learnthat subject; to which I have subjoined one ing of the ancients. The learned, too, are apt experiment from the relation of another gen- to slight too much the knowledge of the vultleman.
gar. The cooling by evaporation was long
an instance of the latter. This art of smoothRev. Mr. Farish to Dr. Brownrigg.
ing the waves by oil is an instance of both.
Perhaps you may not dislike to have an acI SOME time ago met with Mr. Dun, who count of all I have heard, and learnt, and done surprised me with an account of an experi- in this way. Take it if you please as follows: ment you had tried upon the Derwent water, In 1757, being at sea in a fleet of 96 sail in company with sir John Pringle and Dr. bound against Louisburg, I observed the wakes Franklin. According to his representation, of two of the ships to be remarkably smooth, the water, which had been in great agitation while all the others were ruffled by the wind, before, was instantly calmed upon pouring in which blew fresh. Being puzzled with the only a very small quantity of oil, and that to differing appearance, I at last pointed it out to so great a distance round the boat as seemed our captain, and asked him the meaning of it. incredible. I have since had the same ac “ The cooks," says he,“ have, I suppose, been counts from others, but I suspect all of a little just emptying their greasy water through the exaggeration. Pliny mentions this property scuppers, which has greased the sides of those of oil as known particularly to the divers, who ships a little;" and this answer he gave me made use of it in his days, in order to have a with an air of some little contempt, as to a more steady light at the bottom.* The sail- person ignorant of what every body else knew. ors, I have been told, have observed some- In my own mind I at first slighted his soluthing of the same kind in our days, that the tion, though I was not able to think of another, water is always remarkably smoother, in the but recollecting what I had formerly read in wake of a ship that has been newly tallowed, Pliny, I resolved to make some experiment than it is in one that is foul. Mr. Pennant of the effect of oil on water, when I should also mentions an observation of the like nature have opportunity. nade by the seal catchers in Scotland. Brit. Afterwards being again at sea in 1762, I Zool. Vol. iv. Article Seal. When these ani- first observed the wonderful quietness of oil mals are devouring a very oily fish, which on agitated water, in the swinging glass lamp they always do under water, the waves above I made to hang up in the cabin, as described are observed to be remarkably smooth, and by in my printed paper.*
* This I was continuthis mark the fishermen know where to look ally looking at and considering, as an appearfor them. Old Pliny does not usually meet ance to me inexplicable. An old sea captain, with all the credit I am inclined to think he then a passenger with me, thought little of deserves. I shall be glad to have an authentic it, supposing it an effect of the same kind account of the Keswick experiment, and if it with that of oil put on water to smooth it, comes up to the representations that have been which he said was a practice of the Bermumade of it, I shall not much hesitate to believe dians when they would strike fish, which they the old gentleman in another more wonderful could not see if the surface of the water was phenomenon he relates of stilling a tempest ruffled by the wind. This practice I had only by throwing up a little vinegar into the never before heard of, and was obliged to him air.
for the information; though I thought him
mistaken as to the sameness of the experiDr. Franklin to Dr. Brownrigg.
operations being different as well
as the effects. In one case, the water is LONDON, Nov. 7, 1773.
smooth till the oil is put on, and then becomes I THANK you for the remarks of your learn- agitated. In the other it is agitated before ed friend at Carlisle: I had, when a youth, read the oil is applied, and then becomes smooth. and smiled at Pliny's account of a practice The same gentleman told me, he had heard among the seamen of his time, to still the it was a practice with the fishermen of Lis
bon when about to return into the river (if * Note by Dr. Brownrigg.-Sir Gilfred Lawson, who
they saw before them too great a surf upon the served long in the army at Gibraltar, assures me, that the fishermen in that place are accustomed to pour a lit. bar, which they apprehended might fill their Lle oil on the sea, in order to still its motion, that they boats in passing) to empty a bottle or two of which are there very large, and which they take up with oil, into the sea, which would suppress the a proper instrument. This sir Gilfred had often seen breakers, and allow them to pass safely. A there performed, and said the same was practised on other parts of the Spanish coast.
* See the preceding paper.
confirmation of this I have not since had an ous inquiry, and I wish to understand whence, opportunity of obtaining: but discoursing of it it arises. with another person, who had often been in In our journey to the north, when we had the Mediterranean, I was informed, that the the pleasure of seeing you at Ormathwaite, divers there, who, when under water in their we visited the celebrated Mr. Smeaton, near business, need light, which the curling of the Leeds. Being about to show him the smoothsurface interrupts by the refractions of so many ing experiment on a little pond near his house, little waves, let a small quantity of oil now an ingenious pupil of his, Mr. Jessop, then preand then out of their mouths, which rising to sent, told us of an odd appearance on that pond, the surface smooths it, and permits the light which had lately occurred to him. He was to come down to them. All these informa- about to clean a little cup in which he kept oil, tions I at times revolved in my mind, and won and he threw upon the water some flies that had dered to find no mention of them in our books been drowned in the oil. These flies presentof experimental philosophy.
ly began to move, and turn round on the waAt length being at Clapham, where there ter very rapidly, as if they were vigorously is, on the common, a large pond, which I ob- alive, though on examination he found they served one day to be very rough with the wind, were not so. I immediately concluded that I fetched out a cruet of oil, and dropt a little the motion was occasioned by the power of of it on the water. I saw it spread itself with the repulsion above mentioned, and that the surprising swiftness upon the surface; but oil issuing gradually from the spungy body the effect of smoothing the waves was not of the fly continued the motion. He found produced : for I had applied it first on the some more flies drowned in oil, with which leeward side of the pond, where the waves the experiment was repeated before us. To were largest, and the wind drove my oil back show that it was not any effect of life recoverupon the shore. I then went to the windward ed by the flies, I imitated it by little bits of oilside where they began to form ; and there the ed chips and
paper cut in the form of a comma, oil
, though not more than a tea-spoonful, pro- of the size of a common fly; when the stream duced an instant calm over a space several of repelling particles issuing from the point yards square, which spread amazingly, and made the comma turn round the contrary extended itself gradually till it reached the way. This is not a chamber experiment; for lee side, making all that quarter of the pond, it cannot be well repeated in a bowl or dish of perhaps half an acre, as smooth as a looking- water on a table. A considerable surface of glass.
water is necessary to give room for the exAfter this I contrived to take with me, pansion of a small quantity of oil. In a dish whenever I went into the country, a little oil of water, if the smallest drop of oil be let fall in the upper hollow joint of my bamboo cane, in the middle, the whole surface is presently with which I might repeat the experiment as covered with a thin greasy film proceeding opportunity should offer, and I found it con- from the drop; but as soon as that film has stantly to succeed.
reached the sides of the dish, no more will isIn these experiments, one circumstance sue from the drop, but it remains in the form struck me with particular surprise. This of oil, the side of the dish putting a stop to its was the sudden, wide, and forcible spreading dissipation by prohibiting the farther expanof a drop of oil on the face of the water, which sion of the film. I do not know that any body has hitherto con Our friend, sir John Pringle, being soon sidered. If a drop of oil is put on a highly po- after in Scotland, learned there, that those lished marble table, or on a looking-glass that employed in the herring fishery could at a lies horizontally, the drop remains in its place, distance see where the shoals of herrings spreading very. little. But when put on wa- were, by the smoothness of the water over ter, it spreads instantly many feet round, be- them, which might possibly be occasioned, he coming so thin as to produce the prismatic thought, by some oiliness proceeding from their colours, for a considerable space, and beyond bodies. them so much thinner as to be invisible, ex A gentleman from Rhode Island told me, it cept in its effect of smoothing the waves at a had been remarked, that the harbour of Newmuch greater distance. It seems as if a mu- port was ever smooth while any whaling vestual repulsion between its particles took place sels were in it: which probably arose from as soon as it touched the water, and a repul- hence, that the blubber which they sometimes sion so strong as to act on other bodies swim- bring loose in the hold, or the leakage of their ming on the surface, as straw, leaves, chips, barrels, might afford some oil, to mix with &c. forcing them to recede every way from that water, which from time to time they the drop, as from a centre, leaving a large pump out to keep their vessel free, and that clear space. The quantity of this force, and some oil might spread over the surface of the the distance to which it will operate, I have water in the harbour, and prevent the formnot yet ascertained; but I think it is a curi- ing of any waves. VOL. II....2 N
This prevention I would thus endeavour | ward, as may be seen by the smoothness it to explain.
carries with it, quite to the opposite side. There seems to be no natural repulsion be- For the wind being thus prevented from raistween water and air, such as to keep them ing the first wrinkles, that I call the elements from coming into contact with each other.-- of waves, cannot produce waves, which are Hence we find a quantity of air in water ; to be made by continually acting upon, and and if we extract it by means of the air-pump enlarging those elements, and thus the whole the same water, again exposed to the air, will pond is calmed. soon imbibe an equal quantity.
Totally therefore we might suppress the Therefore air in motion, which is wind, in waves in any required place, if we could passing over the smooth surface of water, may come at the windward place where they take rub, as it were, upon that surface, and raise it their rise. This in the ocean can seldom if into wrinkles, which if the wind continues, ever be done. But perhaps something may are the elements of future waves.
be done on particular occasions, to moderate The smallest wave once raised does not the violence of the waves when we are in the immediately subside, and leave the neigh- midst of them, and prevent their breaking bouring water quiet: but in subsiding raises where that would be inconvenient. nearly as much of the water next to it, the For when the wind blows fresh, there are friction of the parts making little difference. continually rising on the back of every great Thus a stone dropped in a pool raises first a wave a number of small ones, which roughen single wave round itself; and leaves it, by its surface, and give the wind hold, as it sinking to the bottom; but that first wave were, to push it with greater force. This subsiding raises a second, the second a third, hold is diminished, by preventing the generaand so on in circles to a great extent. tion of those small ones. And possibly too,
A small power continually operating will when a wave's surface is oiled, the wind in produce a great action. A finger applied to passing over it, may rather in some degree a weighty suspended bell can at first move it press it down, and contribute to prevent it but little; if repeatedly applied, though with rising again, instead of promoting it. no greater strength, the motion increases till This as mere conjecture would have little the bell swings to its utmost height, and with weight, if the apparent effects of pouring oil a force that cannot be resisted by the whole into the midst of waves were not considerable, strength of the arm and body. Thus the and as yet not otherwise accounted for. small first raised waves, being continually When the wind blows so fresh, as that the acted upon by the wind, are, though the wind waves are not sufficiently quick in obeying does not increase in strength, continually in- its impulse, their tops being thinner and creased in magnitude, rising highly and ex- lighter are pushed forward, broken, and tumed tending their bases, so as to include a vast over in a white foam. Common waves lift a mass of water in each wave, which in its mo- vessel without entering it; but these when tion acts with great violence.
large sometimes break above and pour over it, But if there be a mutual repulsion between doing great damage. the particles of oil, and no attraction between That this effect might in any degree be oil and water, oil dropped on water will not prevented, or the height and violence of waves be held together by adhesion to the spot in the sea moderated, we had no certain acwhereon it falls; it will not be imbibed by count; Pliny's authority for the practice of the water; it will be at liberty to expand it- seamen in his time being slighted. But disself; and it will spread on a surface that, be- coursing lately on this subject with his excelsides being smooth to the most perfect degree lency count Bentinck, of Holland, his son the of polish, prevents, perhaps by repelling the honourable captain Bentinck, and the learned oil, all immediate contact, keeping itata minute professor Allemand (to all whom I showed distance from itself: and the expansion will the experiment of smoothing in a windy day continue till the mutual repulsion between the large piece of water at the head of the the particles of the oil is weakened and re-Green Park) a letter was mentioned, which duced to nothing by their distance. had been received by the count from Batavia,
Now I imagine that the wind, blowing over relative to the saving of a Dutch ship in a water thus covered with a film of oil, cannot storm by pouring oil into the sea. I much easily catch upon it, so as to raise the first desired to see that letter, and a copy of it was wrinkles, but slides over it, and leaves it promised me, which I afterward received. smooth as it finds it. It moves a little the oil indeed, which being between it and the water, serves it to slide with, and prevents Mr. Tengnagel to Count Bentinck. friction, as oil does between those parts of a
BATAVIA, January 5, 1770. machine, that would otherwise rub hard toge NEAR the islands Paul and Amsterdam, ther. Hence the oil dropped on the wind- we met with a storm, which had nothing parward side of a pond proceeds gradually to lee- ticular in it worthy of being communicated
to you, except that the captain found himself periment had not, in the main point, the sucobliged for greater safety in' wearing the cess we wished, for no material difference ship, to pour oil into the sea, to prevent the was observed in the height or force of the waves breaking over her, which had an excel surf upon the shore; but those who were in lent effect, and succeeded in preserving us. As the long-boat could observe a tract of smooth he poured out but a little at a time, the East water, the w of the distance in which the India Company owes perhaps its ship to only barge poured the oil, and gradually spreading six demi-ames of olive-oil. I was present up in breadth towards the long-boat. I call it on deck when this was done; and I should smoothed, not that it was laid level; but be. not have mentioned this circumstance to you, cause, though the swell continued, its surface but that we have found people here so preju- was not roughened by the wrinkles, or smaller diced against the experiment, as to make it waves, before-mentioned ; and none or very necessary for the officers on board and myself few white caps (or waves whose tops turn to give a certificate of the truth on this head, over in foam) appeared in that whole space, of which we made no difficulty.
though to windward and leeward of it there On this occasion, I mentioned to captain were plenty ; and a wherry, that came round Bentinck, a thought which had occurred to me the point under sail, in her way to Portsin reading the voyages of our late circumnavi- mouth, seemed to turn into that tract of choice, gators, particularly where accounts are given and to use from end to end, as a piece of of pleasant and fertile islands which they turnpike-road. much desired to land upon, when sickness It may be of use to relate the circumstances made it more necessary, but could not effect of an experiment that does not succeed, since a landing through a violent surf breaking on they may give hints of amendment in future the shore, which rendered it impracticable. trials: it is therefore I have been thus partiMy idea was, that possibly by sailing to and cular. I shall only add what I apprehend fro at some distance from such lee-shore, con- may have been the reason of our disappointtinually pouring oil into the sea, the waves ment. might be so much depressed, and lessened be I conceive, that the operation of oil on wafore they reached the shore, as to abate the ter is, first, to prevent the raising of new height and violence of the surf, and permit a waves by the wind; and, secondly, to prelanding; which, in such circumstances, was vent its pushing those before raised with such a point of sufficient importance to justify the force, and consequently their continuance of expense of the oil that might be requisite for the same repeated height, as they would have the purpose. That gentleman, who is ever done, if their surface were not oiled. But ready to promote what may be of public utili-oil will not prevent waves being raised by ty, though his own ingenious inventions have another power, by a stone, for instance, fallnot always met with the countenance they ing into a still pool; for they then rise by the merited, was so obliging as to invite me to mechanical impulse of the stone, which the Portsmouth, where an opportunity would pro- greasiness on the surrounding water cannot bably offer, in the course of a few days, of lessen or prevent, as it can prevent the winds making the experiment on some of the shores catching the surface and raising it into waves. about Spithead, in which he kindly proposed Now waves once raised, whether by the to accompany me, and to give assistance with wind or any other power, have the same mesuch boats as might be necessary. Accord-chanical operation, by which they continue to ingly, about the middle of October last, I rise and fall
, as a pendulum will continue to went with some friends to Portsmouth; and swing, a long time after the force ceases to a day of wind happening, which made a lee- act by which the motion was first produced : shore between Hasler-hospital and the point that motion will, however, cease in time; but near Jillkecker, we went from the Centaur time is necessary. Therefore, though oil with the long-boat and barge towards that spread on an agitated sea may weaken the shore. Our disposition was this: the long- push of the wind on those waves whose surboat was anchored about a quarter of a mile faces are covered by it, and so, by receiving from the shore; part of the company were fresh impulse, they may gradually subside ; landed behind the point (a place more shelter- yet a considerable time, or a distance through ed from the sea) who came round and placed which they will take time to move, may be themselves opposite to the long boat, where necessary to make the effect sensible on any they might observe the surf, and note if any shore in a diminution of the surf: for we change occurred in it upon using the oil
. know, that when wind ceases suddenly, the Another party, in the barge, plied to wind- waves it has raised do not as suddenly subward of the long boat, as far from her as she side, but settle gradually, and are not quite was from the shore, making trips of about half down till after the wind has ceased. So a mile each, pouring oil continually out of a though we should, by oiling them, take off the large stone bottle, through a hole in the cork, effect of wind on waves already raised, it is somewhat bigger than a goose-quill. The ex- I not to be expected that those waves should be
instantly levelled. The motion they have the twine, will be electrified, and the loose received, will for some time continue; and filaments of the twine will stand out every if the shore is not far distant, they arrive way, and be attracted by an approaching finthere so soon, that their effect upon it will ger. And when the rain has wetted the kite not be visibly diminished. Possibly, therefore, and twine, so that it can conduct the electric if we had begun our operations at a greater fire freely, you will find it stream out plentidistance, the effect might have been more fully from the key on the approach of your sensible. And perhaps we did not pour oil in knuckle. At this key the phial may be sufficient quantity. Future experiments may charged; and from electric fire thus obtained, determine this.
spirits may be kindled, and all the other elecI was, however, greatly obliged to captain tric experiments be performed, which are Bentinck, for the cheerful and ready aids he usually done by the help of a rubbed glass gave me: and I ought not to omit mentioning globe or tube, and thereby the sameness of the Mr. Banks, Dr. Solander, general Carnac, and electric matter with that of lightning comDr. Blagden, who all assisted at the experi- pletely demonstrated. B. FRANKLIN. ment, during that blustering unpleasant day, with a patience and activity that could only
To the same. be inspired by a zeal for the improvement of knowledge, such especially as might possibly Hypothesis, of the Sea being the grand source of be of use to men in situations of distress. Lightning, retracted. Positire, and someI would wish you to communicate this to
times negative, Electricity of the Clouds disco
vered.--New Experiments and Conjectures in your ingenious friend, Mr. Farish, with my
support of this Discovery.- Obserrations rerespects; and believe me to be, with sincere
commended for ascertaining the Direction of esteem,
B. FRANKLIN. the electric Fluid.- Size of Rods for Con
ductors to Buildings.-Appearance of a Thun
der-cloud described. To Peter Collinson, London.
PAILADELPHIA, September, 1753. Electrical Kite.
In my former paper on this subject, written
first in 1747, enlarged and sent to England in PHILADELPHIA, Oct. 16, 1752. 1749, I considered the sea as the grand source As frequent mention is made in public pa- of lightning, imagining its luminous appear. pers from Europe of the success of the Phila- ance to be owing to electric fire produced by delphia experiment for drawing the electric friction between the particles of water and fire from clouds by means of pointed rods of those of salt. Living far from the sea, I had iron erected on high buildings, &c. it may be then no opportunity of making experiments agreeable to the curious to be informed that on the sea water, and so embraced this opithe same experiment has succeeded in Phila- nion too hastily. delphia, though made in a different and more For in 1750, and 1751, being occasionally easy manner, which is as follows:
on the sea-coast, I found by experiments, that Make a small cross of two light strips of sea-water in a bottle, though at first it would cedar, the arms so long as to reach to the four by agitation appear luminous, yet in a few corners of a large thin silk handkerchief when hours it lost that virtue: hence and from this, extended; tie the corners of the handkerchief that I could not by agitating a. solution of seato the extremities of the cross, so you have salt in water produce any light, I first began the body of a kite; which being properly ac- to doubt of my former hypothesis, and to suscommodated with a tail, loop, and string, will pect that the luminous appearance in sea-warise in the air, like those made of paper; but ter must be owing to some other principles. this being of silk is fitter to bear the wet and I then considered whether it were not poswind of a thunder gust without tearing. To sible, that the particles of air, being electrics the top of the upright stick of the cross is to per se, might, in hard gales of wind, by their be fixed a very sharp pointed wire, rising a friction against trees, hills, buildings, &c. ás foot or more above the wood. To the end of so many minute electric globes, rubbing the twine, next the hand, is to be tied a silk against non-electric cushions, draw the elecribbon, and where the silk and twine join, a tric fire from the earth, and that the rising key may be fastened. . This kite is to be raised vapours might receive the fire from the air, when a thunder-gust appears to be coming on, and by such means the clouds become elecand the person who holds the string must trified. stand within a door or window, or under some If this were so, I imagined that by forcing cover, so that the silk ribbon may not be wet; a constant violent stream of air against my and care must be taken that the twine does prime conductor, by bellows, I should electrinot touch the frame of the door or window. fy it negatively; the rubbing particles of air, As soon as any of the thunder clouds come drawing from it part of its natural quantity over the kite, the pointed wire will draw the of the electric fluid. I accordingly made electric fire from them, and the kite, with all the experiment, but it did not succeed.