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in the shell of an egg, and place its longest diameter where the shortest now is, the shell must break; but would be much harder to break, if the whole internal substance were as solid and hard as the shell.

Might not a wave, by any means raised in this supposed internal ocean of extremely dense fluid, raise in some degree, as it passes, the present shell of incumbent earth, and break it in some places, as in earthquakes? And may not the progress of such wave, and the disorders it occasions among the solids of the shell, account for the rumbling sound being first heard at a distance, augmenting as it approaches, and gradually dying away as it proceeds? A circumstance observed by the inhabitants of South America in their last great earthquake, that noise coming from a place, some degrees north of Lima, and being traced by inquiry quite down to Buenos Ayres, proceeded regularly from north to south at the rate of leagues per minute, as I was informed by a very ingenious Peruvian whom I met with at Paris. B. FRANKLIN.

To M. Dubourg.

On the Nature of Sea Coal.

signed to write something on the small-pox shortly. We shall both be obliged to you for a word on this affair.

The chief particulars of our visitation, you have in the public prints. But the less degree of mortality than usual in the common way of infection, seems chiefly owing to the purging method designed to prevent the secondary fever; a sixth, but had we been experienced in this way, at the first method first begun and carried on in this town, and with success beyond expectation. We lost one in eleven, one-coming of the distemper, probably the proportion had been but one in thirteen or fourteen. In the year 1730 we lost one in nine, which is more favourable than ever before with us. The distemper pretty much the same then as now, but some circumstances not so kind this time.

If there be any particulars which you want to know, please to signify what they are, and I shall send them.

The number of our inhabitants decreases. On a strict inquiry, the overseers of the poor find but fourteen thousand one hundred and ninety whites, and one thousand five hundred and forty-four blacks, including those absent on account of the small-pox, many of whom, it is probable, will never return.

thing from your hand, and leave me only liberty to observe, and a power of dissenting when some great probability might oblige me: and if at any time that be the case, you will certainly hear of it.

I AM persuaded, as well as you, that the sea coal has a vegetable origin, and that I pass this opportunity without any particuit has been formed near the surface of the lars of my old theme. One thing, however, I earth; but as preceding convulsions of nature must mention, which is, that perhaps my last had served to bring it very deep in many places, letters contained something that seemed to miand covered it with many different strata, we litate with your doctrine of the Origin, &c. are indebted to subsequent convulsions for But my design was only to relate the phenohaving brought within our view the extremena as they appeared to me. I have receivmities of its veins, so as to lead us to penetrate ed so much light and pleasure from your writ the earth in search of it. I visited last sum-ings, as to prejudice me in favour of every mer a large coal mine at Whitehaven, in Cumberland; and in following the vein and descending by degrees towards the sea, I penetrated below the ocean, where the level of its surface was more than eight hundred fathom above my head, and the miners assured me, that their works extended some miles beyond the place where I then was, continually and The gradually descending under the sea. slate, which forms the roof of this coal mine, is impressed in many places with the figures of leaves and branches of fern, which undoubtedly grew at the surface when the slate was in the state of sand on the banks of the sea. Thus it appears that this vein of coal has suffered a prodigious settlement.

B. FRANKLIN.

Dr. Perkins to Dr. Franklin. Respecting the number of deaths in Philadelphia by Inoculation.

BOSTON, August 3, 1752. SIR,-This comes to you on account of Dr. Douglass he desired me to write to you for what you know of the number that died of the inoculation in Philadelphia, telling me he de

To Dr. Perkins.

Answer to the preceding.

PHILADELPHIA, Aug. 13, 1752. I RECEIVED your favour of the 3d instant. Some time last winter I procured from one of our physicians an account of the number of persons inoculated during the five visitations of the small-pox we have had in twenty-two years; which account I sent to Mr. W. V. of your town, and have no copy. If I remember right, the number exceeded eight hundred, and the deaths were but four. I suppose Mr. V. will show you the account, if he ever received it. Those four were all that our doctors allow to have died of the small-pox by inoculation, though I think there were two more of the inoculated who died of the distemper; but the eruptions appearing soon after the operation,

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it is supposed they had taken the infection be- | still-heads and worms, and the physicians fore, in the common way.

I shall be glad to see what Dr. Douglass may write on the subject. I have a French piece printed at Paris, 1724, entitled, Observations sur la Saignée du Pied, et sur la Purgation au commencement de la Petite Verole, et Raisons de doubte contre l'Inoculation.-A letter of the doctor's is mentioned in it. If he or you have it not, and desire to see it, I will send it.-Please to favour me with the particulars of your purging method, to prevent the secondary fever.

I am indebted for your preceding letter, but business sometimes obliges me to postpone philosophical amusements. Whatever I have wrote of that kind, are really, as they are entitled, but Conjectures and Suppositions; which ought always to give place, when careful observation militates against them. I own I have too strong a penchant to the building of hypotheses; they indulge my natural indolence: I wish I had more of your patience and accuracy in making observations, on which, alone, true philosophy can be founded. And, I assure you, nothing can be more obliging to me, than your kind communication of those you make, however they may disagree with my pre-conceived notions.

were of opinion, that the mischief was occasioned by that use of lead. The legislature of Massachusetts thereupon passed an act, prohibiting, under severe penalties, the use of such still-heads and worms thereafter.

In 1724, being in London, I went to work in the printing-house of Mr. Palmer, Bartholomew-close, as a compositor. I there found a practice, I had never seen before, of drying a case of types (which are wet in distribution) by placing it sloping before the fire. I found this had the additional advantage, when the types were not only dried but heated, of being comfortable to the hands working over them in cold weather. I therefore sometimes heated my case when the types did not want drying. But an old workman observing it, advised me not to do so, telling me I might lose the use of my hands by it, as two of our companions had nearly done, one of whom, that used to earn his guinea a week, could not then make more than ten shillings, and the other, who had the dangles, but seven and sixpence. This, with a kind of obscure pain, that I had sometimes felt, as it were, in the bones of my hand when working over the types made very hot, induced me to omit the practice. But talking afterwards with Mr. James, a letter-founder in the same close, and asking him if his people, who worked over the little furnaces of melted metal, were not subject to that disorder; he made light of any danger from the effluvia, but ascribed it to particles of the metal swallowed with their food by slovenly workmen, who went to their meals after handling the metal, without well washing their fingers, so that some of the metalline particles were taken off by their bread and eaten with it. This appearOn the Effects of Lead upon the human Consti- I had experienced made me still afraid of those ed to have some reason in it. But the pain

I am sorry to hear that the number of your inhabitants decreases. I sometime since, wrote a small paper of Thoughts on the peopling of Countries, which, if I can find, I will send you, to obtain your sentiments. The favourable opinion you express of my writings may, you see, occasion you more trouble than you expected from, B. FRANKLIN.

To Benjamin Vaughan.

tution.*

PHILADELPHIA, July 31, 1786.

I RECOLLECT that when I had last the pleasure of seeing you at Southampton, now a twelvemonth since, we had some conversation on the bad effects of lead taken inwardly; and that at your request I promised to send you in writing a particular account of several facts I then mentioned to you, of which you thought some good use might be made. I now sit down to fulfil that promise.

The first thing I remember of this kind was a general discourse in Boston when I was a boy, of a complaint from North Carolina against New England rum, that it poisoned their people, giving them the dry belly-ache, with a loss of the use of their limbs. The distilleries being examined on the occasion, it was found, that several of them used leaden

*This letter was publihed in a work by Dr. John

Hunter, entitled Observations on the Diseases of the
Army.

effluvia.

naces for smelting of lead ore, I was told, Being in Derbyshire at some of the furthat the smoke of those furnaces was pernicious to the neighbouring grass and other vegetables; but I do not recollect to have heard any thing of the effect of such vegetables eat en by animals. It may be well to make the inquiry.

În America I have often observed, that on the roofs of our shingled-houses, where moss is apt to grow in northern exposures, if there be any thing on the roof painted with white lead, such as balusters, or frames of dormant windows, &c. there is constantly a streak on the shingles from such paint down to the eaves, on which no moss will grow, but the wood remains constantly clean and free from it. We seldom drink rain water that fall on our houses; and if we did, perhaps the small quantity of lead descending from such paint might not be sufficient to pro

duce any sensible ill-effect on our bodies. But | accustomed to see all the animals, with which I have been told of a case in Europe, I forget we are acquainted, eat and drink, it appears the place, where a whole family was afflicted with what we call the dry belly-ache, or colica pictorum, by drinking rain water. It was at a country-seat, which, being situated too high to have the advantage of a well, was supplied with water from a tank, which received the water from the leaded roofs. This had been drank several years without mischief, but some young trees planted near the house growing up above the roof, and shedding their leaves upon it, it was supposed, that an acid in those leaves had corroded the lead they covered, and furnished the water that year with its baneful particles and qualities.

to us difficult to conceive, how a toad can be supported in such a dungeon: but if we reflect, that the necessity of nourishment, which animals experience in their ordinary state, proceeds from the continual waste of their substance by perspiration, it will appear less incredible, that some animals in a torpid state, perspiring less because they use no exercise, should have less need of aliment; and that others, which are covered with scales or shells, which stop perspiration, such as land and sea-turtles, serpents, and some species of fish, should be able to subsist a considerable time without any nourishment whatever.-A plant, with its flowers, fades and dies immediately, if exposed to the air with

When I was in Paris with sir John Pringle in 1767, he visited La Charité, an hospital particularly famous for the cure of that mala-out having its root immersed in a humid soil, dy, and brought from thence a pamphlet, containing a list of the names of persons, specifying their professions or trades, who had been cured there. I had the curiosity to examine that list, and found, that all the patients were of trades, that some way or other use or work in lead; such as plumbers, glaziers, painters, &c. excepting only two kinds, stonecutters, and soldiers. In them, I could not reconcile it to my notion, that lead was the cause of that disorder. But on my mentioning it to a physician of that hospital, he informed me, that the stone-cutters are continually using melted lead to fix the ends of iron balustrades in stone; and that the soldiers had been employed by painters as labourers in grinding of colours.

This, my dear friend, is all I can at present recollect on the subject. You will see by it, that the opinion of this mischievous effect from lead, is at least above sixty years old; and you will observe with concern how long a useful truth may be known and exist, before it is generally received and practised on. B. FRANKLIN.

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-YOUR observations on the causes of death, and the experiments which you propose for recalling to life those who appear to be killed by lightning, demonstrate equally your sagacity and your humanity. It appears, that the doctrines of life and death, in general, are yet but little understood.

A toad buried in sand will live, it is said, till the sand becomes petrified: and then, being enclosed in the stone, it may still live for we know not how many ages. The facts which are cited in support of this opinion are too numerous, and too circumstantial, not to leserve a certain degree of credit. As we are

from which it may draw a sufficient quantity of moisture to supply that which exhales from its substance and is carried off continually by the air. Perhaps, however, if it were buried in quicksilver, it might preserve for a considerable space of time its vegetable life, its smell, and colour. If this be the case, it might prove a commodious method of transporting from distant countries those delicate plants, which are unable to sustain the inclemency of the weather at sea, and which require particular care and attention. I have seen an instance of common flies preserved in a manner somewhat similar. They had been drowned in Madeira wine, apparently about the time when it was bottled in Virginia, to be sent hither (to London). At the opening of one of the bottles, at the house of a friend where I then was, three drowned flies fell into the first glass that was filled. Having heard it remarked, that drowned flies were capable of being revived by the rays of the sun, I proposed making the experiment upon these: they were therefore exposed to the sun upon a sieve, which had been employed to strain them out of the wine. In less than three hours, two of them began by degrees to recover life. They commenced by some convulsive motions of the thighs, and at length they raised themselves upon their legs, wiped their eyes with their fore-feet, beat and brushed their wings with their hind-feet, and soon after began to fly, finding themselves in Old England, without knowing how they came thither. The third continued lifeless till sunset, when, losing all hopes of him, he was thrown away.

I wish it were possible, from this instance, to invent a method of embalming drowned persons, in such a manner that they may be recalled to life at any period, however distant; for having a very ardent desire to see and observe the state of America an hundred years hence, I should prefer to any ordinary death, the being immersed in a cask of Ma

deira wine, with a few friends till that time, | This may be shown by several very easy exto be then recalled to life by the solar warmth periments. Take any clear glass bottle (a of my dear country! But since in all probabili-Florence flask stript of the straw is best) ty we live in an age too early and too near the place it before the fire, and as the air within infancy of science, to hope to see such an art is warmed and rarefied part of it will be driven brought in our time to its perfection, I must out of the bottle; turn it up, place its mouth for the present content myself with the treat, in a vessel of water, and remove it from the which you are so kind as to promise me, of fire; then, as the air within cools and conthe resurrection of a fowl or a turkey-cock. tracts, you will see the water rise in the neck B. FRANKLIN. of the bottle, supplying the place of just so much air as was driven out. Hold a large hot coal near the side of the bottle, and as the and force out the water.-Or, fill a bladder air within feels the heat, it will again distend not quite full of air, tie the neck tight, and lay it before a fire as near as may be without scorching the bladder; as the air within heats, der, till it becomes tight, as if full blown: reyou will perceive it to swell and fill the bladfall gradually, till it becomes as lank as at move it to a cool place, and you will see it

An account of the new-invented Pennsylvanian Fire-Places: wherein their construction and manner of operation is particularly explained; their advantages above every other method of warming rooms demonstrated; and all objections that have been raised against the use of them answered and obviated. With directions for putting them up, and for using them to the best advantage. And a Copper-Plate, in which the several parts of the machine are exactly laid down, from a scale of equal parts. First printed at Philadelphia in 1745.

In these northern colonies the inhabitants keep fires to sit by generally seven months in the year; that is, from the beginning of October, to the end of April; and, in some winters, near eight months, by taking in part of September and May.

Wood, our common fuel, which within these hundred years might be had at every man's door, must now be fetched near one hundred miles to some towns, and makes a very considerable article in the expense of families.

As therefore so much of the comfort and conveniency of our lives, for so great a part of the year, depends on the article of fire; since fuel is become so expensive, and (as the country is more cleared and settled) will of course grow scarcer and dearer, any new proposal for saving the wood, and for lessening the charge, and augmenting the benefit of fire, by some particular method of making and managing it, may at least be thought worth consideration.

The new fire-places are a late invention to that purpose, of which this paper is intended to give a particular account.

first.

2. Air rarefied and distended by heat is spefically* lighter than it was before, and will rise in other air of greater density. As wood, oil, or any other matter specifically lighter than water, if placed at the bottom of a vessel of water, will rise till it comes to the top; so rarefied air will rise in common air, till it either comes to air of equal weight, or is by cold reduced to its former density.

A fire then being made in any chimney, the air over the fire is rarefied by the heat, becomes lighter, and therefore immediately rises in the funnel, and goes out; the other air in the room (flowing towards the chimney) supplies its place, is rarefied in its turn, and rises likewise; the place of the air thus carried out of the room, is supplied by fresh air coming in through doors and windows, or, if they be shut, through every crevice with violence, as may be seen by holding a candle to a key-hole: if the room be so tight as that all the crevices together will not supply so much air as is continually carried off, then, in a little time, the current up the funnel must flag, and the smoke being no longer driven up, must come into the room.

1. Fire (i. e. common fire) throws out light, heat, and smoke (or fume.) The two first move in right lines, and with great swiftness, the latter is but just separated from the fuel, That the reader may the better judge whe- and then moves only as it is carried by the ther this method of managing fire has any ad-stream of rarefied air: and without a contivantage over those heretofore in use, it may nual accession and recession of air, to carry off be proper to consider both the old and new the smoky fumes, they would remain crowded methods separately and particularly, and after- about the fire, and stifle it. wards make the comparison.

In order to this, it is necessary to understand well, some few of the properties of air and fire, viz.

1. Air is rarefied by heat, and condensed by cold, i. e. the same quantity of air takes up more space when warm than when cold.

2. Heat may be separated from the smoke as well as from the light, by means of a plate of iron, which will suffer heat to pass through it without the others.

heavier or lighter than other matter, when it has more *Body or matter of any sort, is said to be specifically or less substance or weight in the same dimensions.

A

2

!

These things being understood, we proceed to consider the fire-places heretofore in use, viz.

3. Fire sends out its rays of heat as well | little understood till lately, that no workman as rays of light equally every way; but the pretended to make one which should always greatest sensible heat is over the fire, where carry off all smoke, but a chimney-cloth was there is, besides the rays of heat shot upwards, looked upon as essential to a chimney. This a continual rising stream of hot air, heated by improvement, however, by small openings the rays shot round on every side. and low breasts, has been made in our days; and success in the first experiments has brought it into general use in cities, so that almost all new chimneys are now made of that sort, and much fewer bricks will make a stack of chimneys now than formerly. An improvement, so lately made, may give us room to believe, that still farther improvements may be found to remedy the inconveniences yet remaining, For these new chimneys, though they keep rooms generally free from smoke, and the opening being contracted; will allow the door to be shut, yet the funnel still requiring a considerable quantity of

1. The large open fire-places used in the days of our fathers, and still generally in the country, and in kitchens.

2. The newer-fashioned fire-places, with low breasts, and narrow hearths.

3. Fire-places with hollow backs, hearths, and jambs of iron (described by M. Gauger, in his tract entitled, La Mechanique de Feu) for warming the air as it comes into the

room.

4. The Holland stoves, with iron doors open-air, it rushes in at every crevice so strongly, ing into the room.

5. The German stoves, which have no opening in the room where they are used, but the fire is put in from some other room, or from without.

6. Iron pots, with open charcoal fires, placed in the middle of a room.

as to make a continual whistling or howling; and it is very uncomfortable, as well as dangerous, to sit against any such crevice. Many colds are caught from this cause only, it being safer to sit in the open street, for then the pores do all close together and the air does not strike so sharply against any particular part of the body.

The Spaniards have a proverbial saying,

If the wind blows on you through a hole,

Make your will, and take care of your soul.

1. The first of these methods has generally the conveniency of two warm seats, one in each corner; but they are sometimes too hot to abide in, and, at other times, incommoded with the smoke; there is likewise good room for the cook to move, to hang on pots, &c. Women particularly from this cause, as they Their inconveniences are, that they almost sit much in the house, get colds in the head, always smoke, if the door be not left open; rheums and defluctions, which fall into their that they require a large funnel, and a large jaws and gums, and have destroyed early many funnel carries off a great quantity of air, a fine set of teeth in these northern colonies. which occasions what is called a strong draft Great and bright fires do also very much conto the chimney, without which strong draft the smoke would come out of some part or tribute to damage the eyes, dry and shrivel the other of so large an opening, so that the door skin, and bring on early the appearances of old age. In short, many of the diseases procan seldom be shut; and the cold air so nips the backs and heels of those that sit before ceeding from colds, as fevers, pleurisies, &c. the fire, that they have no comfort till either fatal to very great numbers of people, may be screens or settles are provided (at a conside- ascribed to strong drawing chimneys, whererable expense) to keep it off, which both cum-fore while he is froze behind.* In the mean by, in severe weather, a man is scorched beber the room, and darken the fire-side. A moderate quantity of wood on the fire, in so large a hearth, seems but little; and, in so strong and cold a draught, warms but little; so that people are continually laying on more. In short, it is next to impossible to warm a room with such a fire-place: and I suppose our ancestors never thought of warming rooms to sit in; all they purposed was, to have a place to make a fire in, by which they might warm themselves when cold.

* As the writer is neither physician nor philosopher, the reader may expect he should justify these his opiF. R. S. in his treatise of The motion of Fluids, says nions by the authority of some that are so. M. Clare, page 246, &c. "And here it may be remarked, that it is more prejudicial to health to sit near a window or a fire, than in a room without; for the consumption of door, in a room where there are many candles and a air thereby occasioned, will always be very considerable, and this must necessarily be replaced by cold air from without. Down the chimney none can enter, the stream of warm air always arising therein absolutely

forbids it, the supply must therefore come in wherever

2. Most of these old-fashioned chimneys in other openings shall be found. If these happen to be small, let those who sit near them beware; the smaller towns and cities, have been, of late years, re- the floodgate, the smarter will be the stream. Was a duced to the second sort mentioned, by build-man, even in a sweat, to leap into a cold bath, or jump from his warm bed, in the intensest cold, even in a ing jambs within them, narrowing the hearth, and making a low arch or breast. It is strange, methinks, that though chimneys have been so long in use, their construction should be so VOL. II.... 3D

frost, provided he do not continue over long therein, and be in health when he does this, we see by experience a window, into which a successive current of cold air that he gets no harm. If he sits a little while against comes, his pores are closed, and he gets a fever. In the

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