Charité_, an hospital particularly famous for the cure of that
malady, 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, stone-cutters 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.
I am, ever, yours most affectionately,
B. FRANKLIN.
FOOTNOTE:
[42] This letter is taken from a work by Dr. John Hunter, entitled
_Observations on the Diseases of the Army_. _Editor._
TO M. DUBOURG[43].
_Observations on the prevailing Doctrines of Life and Death._
**** 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 inclosed 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
deserve a certain degree of credit. As we are accustomed to see all
the animals, with which we are acquainted, eat and drink, it appears
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 without having its
root immersed in a humid soil, 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 Madeira wine, with a few friends till that time, to be then
recalled to life by the solar warmth of my dear country! But since in
all probability we live in an age too early and too near the infancy
of science, to hope to see such an art brought in our time to its
perfection, I must for the present content myself with the treat,
which you are so kind as to promise me, of the resurrection of a fowl
or a turkey-cock.
I am, &c.
B. FRANKLIN.
FOOTNOTE:
[43] This letter is translated from the French edition of Dr.
Franklin's works. It has no date, but the letter to which it is an
answer is dated 15th April, 1773.
_An Account of the new-invented Pensylvanian 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._
BY B. FRANKLIN.
(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 expence 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.
That the reader may the better judge whether this method of managing
fire has any advantage over those heretofore in use, it may be proper
to consider both the old and new methods separately and particularly,
and afterwards 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.
This may be shown by several very easy experiments. Take any clear
glass bottle (a Florence flask stript of the straw is best) place it
before the fire, and as the air within is warmed and rarefied, part
of it will be driven out of the bottle; turn it up, place its mouth
in a vessel of water, and remove it from the fire; then, as the air
within cools and contracts, you will see the water rise in the neck
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
air within feels the heat, it will again distend and force out the
water.--Or, fill a bladder 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, you will perceive it to swell and
fill the bladder, till it becomes tight, as if full blown: remove it
to a cool place, and you will see it fall gradually, till it becomes
as lank as at first.
2. Air rarefied and distended by heat is[44] specifically
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, and then moves
only as it is carried by the stream of rarefied air: and without a
continual accession and recession of air, to carry off the smoaky
fumes, they would remain crouded about the fire, and stifle it.
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.
3. Fire sends out its rays of heat as well as rays of light, equally
every way; but the greatest sensible heat is over the fire, where
there is, besides the rays of heat shot upwards, a continual rising
stream of hot air, heated by the rays shot round on every side.
These things being understood, we proceed to consider the fire-places
heretofore in use, _viz._
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 jams 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 opening 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.
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. Their
inconveniencies are, that they almost always smoke, if the door be
not left open; that they require a large funnel, and a large funnel
carries off a great quantity of air, which occasions what is called
a strong draft to the chimney, without which strong draft the smoke
would come out of some part or other of so large an opening, so that
the door can seldom be shut; and the cold air so nips the backs and
heels of those that sit before the fire, that they have no comfort
till either screens or settles are provided (at a considerable
expence) to keep it off, which both cumber 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.
2. Most of these old-fashioned chimneys in towns and cities, have
been, of late years, reduced to the second sort mentioned, by
building 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 little
understood till lately, that no workman pretended to make one which
should always carry off all smoke, but a chimney-cloth was looked
upon as essential to a chimney. This improvement, however, by small
openings 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 inconveniencies 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 air, it rushes in at every crevice so strongly, 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.
Women particularly, from this cause, as they sit much in the house,
get colds in the head, rheums and defluctions, which fall into their
jaws and gums, and have destroyed early many a fine set of teeth in
these northern colonies. Great and bright fires do also very much
contribute to damage the eyes, dry and shrivel the skin, and bring
on early the appearances of old age. In short, many of the diseases
proceeding from colds, as fevers, pleurisies, &c. fatal to very
great numbers of people, may be ascribed to strong drawing chimneys,
whereby, in severe weather, a man is scorched before while he is
froze behind.[45] In the mean time, very little is done by these
chimneys towards warming the room; for the air round the fire-place,
which is warmed by the direct rays from the fire, does not continue
in the room, but is continually crouded and gathered into the chimney
by the current of cold air coming behind it, and so is presently
carried off.
In both these sorts of fire-places, the greatest part of the heat
from the fire is lost; for as fire naturally darts heat every way,
the back, the two jambs, and the hearth, drink up almost all that is
given them, very little being reflected from bodies so dark, porous,
and unpolished; and the upright heat, which is by far the greatest,
flies directly up the chimney. Thus five-sixths at least of the heat
(and consequently of the fuel) is wasted, and contributes nothing
towards warming the room.
3. To remedy this, the Sieur Gauger gives, in his book entitled, La
Mechanique de Feu, published in 1709, seven different constructions
of the third sort of chimneys mentioned above, in which there are
hollow cavities made by iron plates in the back, jambs, and hearths,
through which plates the heat passing warms the air in those
cavities, which is continually coming into the room fresh and warm.
The invention was very ingenious, and had many conveniencies: the
room was warmed in all parts, by the air flowing into it through the
heated cavities: cold air was prevented rushing through the crevices,
the funnel being sufficiently supplied by those cavities: much less
fuel would serve, &c. But the first expence, which was very great,
the intricacy of the design, and the difficulty of the execution,
especially in old chimneys, discouraged the propagation of the
invention; so that there are, I suppose, very few such chimneys now
in use. [The upright heat, too, was almost all lost in these, as in
the common chimneys.]
4. The Holland iron stove, which has a flue proceeding from the
top, and a small iron door opening into the room, comes next to be
considered. Its conveniencies are, that it makes a room all over
warm; for the chimney being wholly closed, except the flue of the
stove, very little air is required to supply that, and therefore not
much rushes in at crevices, or at the door when it is opened. Little
fuel serves, the heat being almost all saved; for it rays out almost
equally from the four sides, the bottom and the top, into the room,
and presently warms the air around it, which, being rarefied, rises
to the ceiling, and its place is supplied by the lower air of the
room, which flows gradually towards the stove, and is there warmed,
and rises in its turn, so that there is a continual circulation
till all the air in the room is warmed. The air, too, is gradually
changed, by the stove-door's being in the room, through which part of
it is continually passing, and that makes these stoves wholesomer,
or at least pleasanter than the German stoves, next to be spoken of.
But they have these inconveniencies. There is no sight of the fire,
which is in itself a pleasant thing. One cannot conveniently make
any other use of the fire but that of warming the room. When the room
is warm, people, not seeing the fire, are apt to forget supplying it
with fuel till it is almost out, then, growing cold, a great deal
of wood is put in, which soon makes it too hot. The change of air
is not carried on quite quick enough, so that if any smoke or ill
smell happens in the room, it is a long time before it is discharged.
For these reasons the Holland stove has not obtained much among the
English (who love the sight of the fire) unless in some workshops,
where people are obliged to sit near windows for the light, and in
such places they have been found of good use.
5. The German stove is like a box, one side wanting. It is composed
of five iron plates screwed together, and fixed so as that you may
put the fuel into it from another room, or from the outside of the
house. It is a kind of oven reversed, its mouth being without, and
body within the room that is to be warmed by it. This invention
certainly warms a room very speedily and thoroughly with little fuel:
no quantity of cold air comes in at any crevice, because there is
no discharge of air which it might supply, there being no passage
into the stove from the room. These are its conveniencies. Its
inconveniencies are, that people have not even so much sight or use
of the fire as in the Holland stoves, and are, moreover, obliged to
breathe the same unchanged air continually, mixed with the breath and
perspiration from one another's bodies, which is very disagreeable to
those who have not been accustomed to it.
[Illustration: (of the Pensylvania fireplace)
_Plate VIII._ _Vol. II. page 235._
_Published as the Act directs, April 1, 1806, by Longman, Hurst, Rees
& Orme, Paternoster Row._]
6. Charcoal fires in pots are used chiefly in the shops of
handicraftsmen. They warm a room (that is kept close, and has no
chimney to carry off the warmed air) very speedily and uniformly; but
there being no draught to change the air, the sulphurous fumes from
the coals [be they ever so well kindled before they are brought in,
there will be some] mix with it, render it disagreeable, hurtful to
some constitutions, and sometimes, when the door is long kept shut,
produce fatal consequences.
To avoid the several inconveniencies, and at the same time retain all
the advantages of other fire-places, was contrived the Pensylvania
fire-place, now to be described.
This machine consists of
A bottom-plate, (i) (_See the Plate annexed_.)
A back plate, (ii)
Two side plates, (iii iii)
Two middle plates, (iv iv) which, joined together, form a tight box,
with winding passages in it for warming the air.
A front plate, (v)
A top plate (vi)
These are all cast of iron, with mouldings or ledges where the
plates come together, to hold them fast, and retain the mortar used
for pointing to make tight joints. When the plates are all in their
places, a pair of slender rods, with screws, are sufficient to bind
the whole very firmly together, as it appears in Fig. 2.
There are, moreover, two thin plates of wrought iron, viz. the
shutter, (vii) and the register, (viii); besides the screw-rods O P,
all which we shall explain in their order.
(i) The bottom plate, or hearth-piece, is round before, with a
rising moulding, that serves as a fender to keep coals and ashes from
coming to the floor, &c. It has two ears, F G, perforated to receive
the screw-rods O P; a long air-hole, _a a_, through which the fresh
outward air passes up into the air-box; and three smoke-holes B C,
through which the smoke descends and passes away; all represented
by dark squares. It has also double ledges to receive between them
the bottom edges of the back plate, the two side-plates, and the two
middle plates. These ledges are about an inch asunder, and about
half an inch high; a profile of two of them, joined to a fragment of
plate, appears in Fig. 3.
(ii) The back plate is without holes, having only a pair of ledges on
each side, to receive the back edges of the two.
(iii iii) Side-plates: These have each a pair of ledges to receive
the side-edges of the front-plate, and a little shoulder for it to
rest on; also two pair of ledges to receive the side-edges of the two
middle plates which form the air-box; and an oblong air-hole near the
top, through which is discharged into the room the air warmed in the
air-box. Each has also a wing or bracket, H and I, to keep in falling
brands, coals, &c. and a small hole, Q and R, for the axis of the
register to turn in.
(iv iv) The air-box is composed of the two middle plates, D E and
F G. The first has five thin ledges or partitions cast on it, two
inches deep, the edges of which are received in so many pair of
ledges cast in the other. The tops of all the cavities formed by
these thin deep ledges, are also covered by a ledge of the same form
and depth, cast with them; so that when the plates are put together,
and the joints luted, there is no communication between the air-box
and the smoke. In the winding passages of this box, fresh air is
warmed as it passes into the room.
(v) The front plate is arched on the under side, and ornamented with
foliages, &c. it has no ledges.
(vi) The top plate has a pair of ears, M N, answerable to those in
the bottom plate, and perforated for the same purpose: it has also a
pair of ledges running round the under side, to receive the top edges
of the front, back, and side-plates. The air-box does not reach up to
the top plate by two inches and a half.
(vii) The shutter is of thin wrought iron and light, of such a length
and breadth as to close well the opening of the fire-place. It is
used to blow up the fire, and to shut up and secure it at nights. It
has two brass knobs for handles, _d d_, and commonly slides up and
down in a groove, left, in putting up the fire-place, between the
foremost ledge of the side-plates, and the face of the front plate;
but some chuse to set it aside when it is not in use, and apply it on
occasion.
(viii) The register is also of thin wrought iron. It is placed
between the back plate and air-box, and can, by means of the key S,
be turned on its axis so as to lie in any position between level and
upright.
The screw-rods O P are of wrought iron, about a third of an inch
thick, with a button at bottom, and a screw and nut at top, and may
be ornamented with two small brasses screwed on above the nuts.
To put this machine to work,
1. A false back of four inch (or, in shallow small chimneys, two
inch) brick work is to be made in the chimney, four inches or more
from the true back; from the top of this false back a closing is to
be made over to the breast of the chimney, that no air may pass into
the chimney, but what goes under the false back, and up behind it.
2. Some bricks of the hearth are to be taken up, to form a hollow
under the bottom plate; across which hollow runs a thin tight
partition, to keep apart the air entering the hollow and the smoke;
and is therefore placed between the air-hole and smoke-holes.
3. A passage is made, communicating with the outward air, to
introduce that air into the fore part of the hollow under the bottom
plate, whence it may rise through the air-hole into the air-box.