cannot be recovered, it is to be presumed, will repeat the experiments themselves.'

DEAR SIR,

TO DR. RUSH.

London, July 14, 1773.

I received your favor of May 1 with the pamphlet, for which I am obliged to you. It is well written. I hope that in time the endeavors of the friends to liberty and humanity will get the better of a practice that has so long disgraced our nation and religion.

A few days after I received your packet for M. Dubourg, I had an opportunity of forwarding it to him per M. Poissonier, physician of Paris, who kindly undertook to deliver it. M. Dubourg has been translating my book* into French. It is nearly printed, and he tells me he purposes a copy for you.

I shall communicate your judicious remark relating to the septic quality of the air transpired by patients in putrid diseases to my friend Dr. Priestly. I hope that after having discovered the benefit of fresh and cool air applied to the sick, people will begin to suspect that possibly it may do no harm to the well. I have not seen Dr. Cullen's book, but am glad to hear that he speaks of catarrhs or colds by contagion. I have long been satisfied from observation, that besides the general colds now termed influenzas (which may possibly spread by contagion as well as by a particular quality of the air) people often catch cold from one another when shut up together in close rooms, coaches, &c. and when sitting near and conversing so as to breathe in each other's transpiration; the disorder being in a certain state. I think too that it is the frowzy corrupt air from animal substances, and the perspired matter from our bodies, which being long confined in beds not lately used, and clothes not lately worn, and books long shut up in close rooms, obtains that kind of putridity which occasions the colds observed upon sleeping in, wearing, and turning over such bed, clothes, or books, and not their coldness or dampness. From these causes, but more from too full living, with too little exercise, proceed in my opinion most of the disorders which for about one hundred and fifty years past

'The young physician here alluded to, is the late Dr. Stark, whose works, including the above experiments, have since been published.

2 Experiments in electricity.

the English have called colds. As to Dr. Cullen's cold or catarrh a frigore, I question whether such a one ever existed. Travelling in our severe winters, I have suffered cold sometimes to an extremity only short of freezing, but this did not make me catch cold. And for moisture, I have been in the river every evening two or three hours for a fortnight together, when one would suppose I might imbibe enough of it to take cold if humidity could give it; but no such effect ever followed. Boys never get cold by swimming. Nor are people at sea, or who live at Bermudas, or St. Helena, small islands, where the air must be ever moist from the dashing and breaking of waves against their rocks on all sides, more subject to colds than those who inhabit part of a continent where the air is driest. Dampness may indeed assist in producing putridity and those miasmata which infect us with the disorder we call a cold; but of itself can never by a little addition of moisture hurt a body filled with watery fluids from head to foot. With great esteem and sincere wishes for your welfare, I am, Sir, your most obedient humble servant, B. FRANKLIN.

MOIST AIR NOT UNHEALTHY.
TO DR. PERCIVAL.

London, Oct. 15, 1773.

"The difference of deaths between 1 in 28 at Manchester, and 1 in 120 at Morton, is surprising. It seems to show the unwholesomeness of the manufacturing life, owing perhaps to the confinement in small close rooms, or in larger with numbers, or to poverty and want of necessaries, or to drinking, or to all of them. Farmers who manufacture in their own families what they have occasion for and no more, are perhaps the happiest people and the healthiest.

"Tis a curious remark, that moist seasons are the healthiest. The gentry of England are remarkably afraid of moisture, and of air. But seamen, who live in perpetually moist air, are always healthy, if they have good provisions. The inhabitants of Bermuda, St. Helena, and other islands far from continents, surrounded with rocks against which the waves continually dashing fill the air with spray and vapor, and where no wind can arrive that does not pass over much sea, and of course bring much moisture, these people are remarkably healthy. And I have long thought that mere moist air has no ill effect on the

constitution; though air impregnated with vapors from putrid marshes is found pernicious, not from the moisture but the putridity. It seems strange that a man, whose body is composed in great part of moist fluids, whose blood and juices are so watery, who can swallow quantities of water and small beer daily without inconvenience, should fancy that a little more or less moisture in the air should be of such importance. But we abound in absurdity and inconsistency. Thus though it is generally allowed that taking the air is a good thing, yet what caution against air! what stopping of crevices! what wrapping up in warm clothes! what stuffing of doors and windows! even in the midst of summer. Many London families go out once a day to take the air; three or four persons in a coach, one perhaps sick; these go three or four miles, or as many turns in Hyde Park, with the glasses both up close, all breathing over and over again the same air they brought out of town with them in the coach, with the least change possible, and rendered worse and worse every moment. And this they call taking the air. From many years observations on myself and others, I am persuaded we are on a wrong scent in supposing moist or cold air the causes of that disorder we call a cold: some unknown quality in the air may perhaps produce colds, as in the influenza; but generally I apprehend they are the effect of too full living in proportion to our exercise. Excuse, if you can, my intruding into your province, and believe me ever with sincere esteem, dear sir, your most obedient humble servant, B. FRANKLIN.

ON LIGHTNING CONDUCTORS.

TO MR. WINTHROP.

London, July 25, 1773.

Your remark on the passage of Castillioneus will be read at the society at their next meeting. I thank you much for the papers and accounts of damage done by lightning, which you have favored me with. The conductors begin to be used here. Many country seats are provided with them, some churches, the powder magazines at Purfleet, the queen's house in the park, &c. and M. Le Roy of the Academy of Sciences at Paris, has lately given a Memoir recommending the use of them in that kingdom, which has

been long opposed and obstructed by Abbé Nollet. Of the Duke of Tuscany he says, "Ce prince, qui ne connoît pas de délassement plus agréable des soins pénibles du gouvernement, que l'étude de la Physique, a ordonné, l'année der nière, qu'on établît de ces barres au-dessus de tous les magasins à poudre de ses Etats; on dit que la république de Venise a donné les mêmes ordres, &c."

B. FRANKLIN.

OF THE STILLING OF WAVES BY MEANS OF OIL. EXTRACTED FROM SUNDRY LETTERS BETWEEN DR. FRANKLIN, WILLIAM BROWNRIGG, M.D. F.R.S. AND THE REV. MR. FARISH.

Extract of a Letter from Dr. Brownrigg to Dr. Franklin, dated Ormathwait, January 27, 1773.

By the enclosed from an old friend, a worthy clergyman at Carlisle, whose great learning and extensive knowledge in most sciences would have more distinguised him, had he been placed in a more conspicuous point of view, you will find, that he had heard of your experiment on Derwent Lake, and has thrown together what he could collect on that subject; to which I have subjoined one experiment from the relation of another gentleman.

Extract of a Letter from the Rev. Mr. Farish to Dr. Brownrigg.

I some time ago met with Mr. Dun, who surprised me with an account of an experiment you had tried upon the Derwent water, in company with Sir John Pringle and Dr. Franklin. According to his representation, the water, which had been in a great agitation before, was instantly calmed upon pouring in only a very small quantity of oil, and that to so great a distance round the boat as seemed incredible. I have since had the same accounts from others, but I suspect all of a little exaggeration. Pliny mentions this property of oil as known particularly to the divers, who made use of it in his days, in order to

have a more steady light at the bottom. The sailors, I have been told, have observed something of the same kind in our days, that the water is always remarkably smoother, in the wake of a ship that has been newly tallowed, than it is in one that is foul. Mr. Pennant also mentions an observation of the like nature made by the seal-catchers in Scotland. Brit. Zool. Vol. iv. Article Seal. When these animals are devouring a very oily fish, which they always do under water, the waves above are observed to be remarkably smooth, and by this mark the fishermen know where to look for them. 'Old Pliny does not usually meet with all the credit I am inclined to think he deserves. I shall be glad to have an authentic account of the Keswick experiment; and if it comes up to the representations that have been made of it, I shall not much hesitate to believe the old gentleman in another more wonderful phenomenon he relates of stilling a tempest only by throwing up a little vinegar into the air

DR. FRANKLIN TO DR. BROWNRIGG.

London, Nov. 7, 1773.

DEAR SIR, I thank you for the remarks of your learned friend at Carlisle: I had, when a youth, read and smiled at Pliny's account of a practice among the seamen of his time, to still the waves in a storm by pouring oil into the sea; which he mentions, as well as the use of oil by the divers; but the stilling a tempest by throwing vinegar into the air had escaped me. I think with your friend, that it has been of late too much the mode to slight the learning of the ancients. The learned, too, are apt to slight too much the knowledge of the vulgar. The cooling by evaporation was long an instance of the latter. This art of smoothing the waves by oil is an instance of both.

Perhaps you may not dislike to have an account of all I have heard, and learnt, and done in this way. Take it, if you please, as follows:

Note by Dr. Brownrigg.

'Sir Gilfred Lawson, who served long in the army at Gibraltar, assures me, that the fishermen in that place are accustomed to pour a little oil on the sea, in order to still its motion, that they may be enabled to see the oysters lying at its bottom, which are there very large, and which they take up with a proper instrument. This Sir Gilfred had often seen this performed, and said the same was practised on other parts of the Spanish coast.

VOL. III.

3 H