fathers, and which appears to be of confiderable use to them in their refpective employments. The divers in the Mediterranean, in particular, defcend, as in Pliny's time, with a little oil in their mouths, which they now and then let out; and which, on rifing to the furface of the fea, immediately renders it fmooth, fo as to permit the light to pafs through the water, undisturbed by various and irregular refractions.

The Bermudians, it is here faid, are enabled to fee and ftrike fifh, which would be concealed from their view through the roughness of the fea, by pouring a little oil upon it. And the Lifbon fishermen, it is added, effect a fafe paffage over the bar of the Tagus, by emptying a bottle or two of oil into the fea,, when the furf is fo great as to endanger its filling their boats.

Dr. Franklin had formerly read and fmiled at Pliny's account; but an accidental obfervation made at fea caufed him first to attend particularly to it; and the various informations which he afterwards received relating to it, induced him to try fome experiments on the fubject. Standing on the windward fide of a large pond at Clapham, the furface of which was rendered very rough with the wind, he poured a tea-fpoonful of oil on the water. He had the pleature to fee this fmall quantity produce an inftant calm over a fpace feveral yards fquare, which spread amazingly, and extended itself gradually till it reached the lee fide, making all that quarter of the pond, perhaps half an acre, as fmooth as a looking glafs.'

On repeating this experiment, which conftantly fucceeded, one circumftance ftruck the Author with particular furprize.

This was the fudden, wide, and forcible fpreading of a drop of oil on the face of the water, which,' he adds, I do not know that any body has confidered.' When a drop of oil is put on a looking glafs, or polifhed marble, it fpreads very little; but on water it inftantly expands into a circle extending feveral feet in diameter; becoming fo thin as to produce the prifmatic colours, for a confiderable fpace, and beyond them fo much thinner as to be invifible, except in its effect of fmoothing the waves at a much greater distance.' It feems, fays the Author,

6

as if a mutual repulfion between its particles took place as foon as it touched the water, and a repulfion fo ftrong as to act on other bodies fwimming on the furface, as ftraws, leaves, chips, &c. forcing them to recede every way from the drop, as from a center, leaving a large clear fpace. The quantity of this force, and the diftance to which it will operate, I have not yet afcertained; but I think it a curious inquiry, and I wish to understand whence it arifes ?

In endeavouring to account for the fingular effects of oil, in the fmoothing of waves, the Author offers a very ingenious and

natural

natural folution of the principal appearances: but it is not eafy to abridge or condenfe the writings of so close a reafoner as Dr. Franklin; nor will our limits allow us to tranfcribe the whole of his explanation; for which we must therefore refer the curious to the Article itself.

On the whole, there is great room to fuppofe (notwithstanding the partial failure of an experiment made at Portsmouth by the Author, affifted by the Hon. Capt. Bentinck, Mr Banks, Dr. Solander, and others) that fea-faring people may derive advantages from ufing oil on particular occafions, in order to moderate the violence of the waves, or to leffen the furf which fometimes renders the landing on a lee-fhore dangerous or impracticable. The following relation fhews that oil has been lately thus employed with great advantage.

The Author having fhewn the experiment of fmoothing the large piece of water at the head of the Green Park, in a windy day, to his Excellency Count Bentinck and Profeffor Allemand, his Excellency mentioned a letter which he had received from Batavia, relative to the faving a Dutch Eaft India fhip in a ftorm, by pouring oil into the fea. The following is an extract from this letter, dated at Batavia, Jan. 15, 1770.

"Near the islands Paul and Amfterdam, we met with a ftorm"-in which the Captain found himself obliged, for greater fafety in wearing the fhip, to pour oil into the fea, to prevent the waves breaking over her, which had an excellent effect, and fucceeded in preferving us.-As he poured out but a little at a time, the Eaft India Company owes perhaps its hip to only fix demi-aumes of oil olive. I was prefent upon deck when this was done; and i fhould not have mentioned this circumstance to you, but that we have found people here fo preju diced against the experiment, as to make it neceflary for the officers on board and myself to give a certificate of the truth on this head, of which we made no difficulty."

Article 42. On the Revivifcence of fame Snails preferved many Years in Mr. Simon's Cabinet: In a Letter from David Macbride, M. D. to John Walth, Efq; F. R. S.

That we may avoid the two contrary imputations of exceffive credulity and unreafonable fcepticiim, we fhall fimply relate the principal facts endeavoured to be eftablished in this Article, without entering into a minute detail of the circumftances. They are certainly of a very fingular nature, but not perhaps more extraordinary than the phenomena which the fnail has lately prefented to certain naturalifts; with whom it has lived feveral months after its head has been completely taken off, and has then produced a new head provided with its proper organs. The last fact has indeed been denied by fome unfuccefsful operators; but it is now, we believe, put out of all

Y 4

doubt

doubt by many other philofophers, who have fuccessfully repeated M. Spalanzani's experiments †.

The Author of the prefent obfervation is Mr. Stuckey Simon, a merchant in Dublin, of a very refpectable character and undoubted veracity.' Having occafion, we are told, to arrange fome fhells in a drawer which contained a collection of foffils that had been in his poffeffion ever fince the death of his father 15 years ago, he gave fome fnail fhells that lay among them to his fon, a child about ten years old. Some days afterwards he found feveral of thefe fnails alive in a bafon into which the child had put them. They had however been a long time in water; to which circumftance the Author afcribes the fubfequent death of all of them except one, which furvived, and has been fhewn, at different times, to many learned and curious perfons at Dublin, named in this Article. This fnail was afterwards fent to Sir John Pringle, who fhewed it, ftill alive as we fuppofe, at a meeting of the Royal Society.

To obviate certain doubts that may arife in the minds of those who may be ftruck with the fingularity of this relation, it is obferved that, as Mr. Simon lives in the middle of the city, it is almost impoffible that his fon, had he been fo difpofed, could have fubftituted frefh fhells, with a view of impofing them on his father for those which he had given him; efpecially as he was, at that time, and for feveral days afterwards, confined to the house with a cold.

Article 36. Experiments on Animal Fluids in the exhaufted Re ceiver: By D. Darwin, M. D. Communicated by Dr.

Franklin.

From the results of the experiments related in this Article the Author infers, that the phenomena exhibited by blood in an exhaufted receiver, where it fwells and rifes into bubbles, are fallacious; fo far as they are fuppofed to indicate the existence of air, or of an elaftic vapour contained in that fluid, while it circulated in the veffels of the animal. He is induced to think that these appearances are owing to atmospheric air, which is combined with the blood during its paffage from the vein into the veffel which receives it; and further concludes, that experiments made on the chemical and other properties of blood, thus circumftanced, are rendered very uncertain and erroneous; fince fome of its properties, particularly that of coagulation, and perhaps of putrefaction, may depend on this adventitious commixture of atmospheric air. The following is the fubftance of

Among others we may refer to the recent experiments of M. Muller, related in the work lately published by that gentleman, (Vermium, &c. Hiftoria) of which an account was given in our Re view for February last, page 167.

the

the experiments on which the Author founds these conclufions, with refpect to the blood. Others are related, from which it appears that neither the contents of the urinary or gall bladder, when deprived of all communication with the external air, fhewed any figns of expanfion, on removing the preffure of the atmosphere.

A part of the jugular vein, and of the Vena Cava, were included between two tight ligatures, at the time of flaughtering the animals. Being cut out beyond the ligatures, they were put into a glass of warm water, in which they funk. On being placed under the receiver, they did not rise on exhaufting the air; nor on their being wiped dry, and laid on the brass floor of the receiver, the air being again exhaufted, could there be perceived the leaft vifible expansion of the veins, or of their

contents.

The Author's experiments, as well as fome others of a different kind made by the late Mr. Hewfon *, certainly fhew that the phenomena prefented by blood, while it is contained in its proper veffels, perfectly filled with it, and fecluded from the action of the common air, differ confiderably from those which are obferved in blood that has been expofed to the atmofphere. It is not however, we apprehend, to be concluded from hence, or from the foregoing experiments, that the blood, when cir culating in the veffels, does not contain air, because none was perceived to arife from it, on taking off the preffure of the atmofphere. For it does not feem probable that the great quantities of fixed or other air, which have, by Dr. Hales and others, been procured from that fluid, by fermentation, diftillation, and otherwise, were totally foreign to it when in its circulating ftate, and were received into it after it came into contact with the common air.

Article 39. Continuation of an experimental Inquiry concerning the Nature of the Mineral Elaftic Spirit, or Air, contained in the Pouhon Water, and other Acidule: By W. Brownrigg, M. D.

F. R. S.

The difcovery made by the ingenious Author of this Article, of the fixed, or mephitic air, which he detected in the Pouhon or Pyrmont waters, was communicated to the Public in the 55th volume of the Philofophical Tranfactions. It probably formed the bafis of the many curious inquiries and difcoveries relating to this aerial fluid, fince profecuted and effected by Mr. Cavendish, Mr. Lane, Dr. Priestley, and others.

The Author having been defired to perform the promise long fince given by him, in his former paper, of communicating the further obfervations which he had then made on this fub

• See M. Review, vol. xlvi. April 1772, page 422.

ject,

ject, has here complied with that request: and although, in confequence of his having delayed the publication of them fo long, he has been anticipated in many particulars by the writers abovementioned; the prefent paper contains fome remarks which tend to throw new lights on the fubject of his inquiry.

In the 48th Article, Dr. Brownrigg defcribes feveral fpecimens of native falts, collected by him in the coal mines near Whitehaven; and which, having been firft fhewn to the Royal Society, have fince been depofited in the British Museum.

PAPERS relating to ELECTRICIT Y. Article 41. An Account of fome new Experiments in Electricity, &c. By William Henly, F. R. S.

. This Article contains fome curious experiments, principally contrived with a view to elucidate fome of the more obfcure or contraverted points in electricity.

- It is divided into fix fections; in the first of which the Author relates fome experiments which fhew that fmoak, and the vapour of hot water, are actual, though imperfect, conductors of the electric fluid; and that the former tranfmits electricity more readily than the latter.. On this occafion the Author mentions Dr. Franklin's curious but difficult experiment, of making a visible atmosphere round an infulated electrified body; which has often been executed by Mr. Henly in the following

manner :

At a time when the air is very dry, he perfectly infulates a piece of metal (the brass cafe of a fteel yard weight, about 2 inches in diameter) on a stand of fealing wax. Having a burning green wax taper in readinefs, he gives the infulated body a spark from the knob of a charged vial; and then blowing out the taper, he brings it to the infulated metal very gently, fo as to cause as little motion in the air as poffible. The fmoak is inftantly, and with a kind of violence, attracted to it, till it becomes completely covered with it.' After having furrounded it some time, it first disappears at the bottom, and at length leaves the top of the infulated body; where it hangs quivering, like the departing flame of a lamp: going off in a long thin column, which rarefies and difperfes at the top, till it occupies a great space. The green wax taper is very convenient in this and other electrical experiments; as it continues to yield fmoak, fometimes during a quarter or even half an hour after the flame has been blown out.

The fecond fection contains feveral experiments, made with a view to ascertain the direction of the electric matter in the discharge of the Leyden vial. In the firft of these experiments it is fhewn, that the flame of a wax taper, placed near to, and in the middle between, the knob of a pofitively charged vial, and a ball communicating with the coating, will be driven from the

bnob,