letter continued] have not disdained to amuse
themselves with making and launching balloons,
otherwise we should never have enjoyed the light of
those glorious objects that rule our day and night, nor
have had the pleasure of riding round the sun ourselves
upon the balloon we now inhabit.
In due course, the Messrs. Robert, accompanied by M. Charles, a professor
of experimental philosophy, and an enthusiastic student of aeronautics,
made their perilous venture, which was likewise fully chronicled by
Franklin. The spectators, he said, were infinite, crowding about the
Tuileries, on the quays and bridges, in the fields and streets, and at the
windows, and on the roofs, of houses. The device of stimulating flagging
ascent by dropping sand bags from the car was one of the features of this
incident, and so was the device of protecting the envelope of the balloon
from rupture by covering it with a net, as well as that of lowering it by
letting a part of its contents escape through a valve controlled by a
cord.
Between one and two o'clock [Franklin's narrative
states] all eyes were gratified with seeing it rise
majestically from among the trees, and ascend gradually
above the buildings, a most beautiful spectacle. When
it was about two hundred feet high, the brave
adventurers held out and waved a little white pennant,
on both sides their car, to salute the spectators who
returned loud claps of applause.
When Franklin last saw the vanishing form of this balloon, it appeared no
bigger than a walnut. The experiment proved a most prosperous one. From
first to last the aerial navigators retained perfect command of their
air-ship, descending, when they pleased, by letting some of the air in it
escape, and rising, when they pleased, by discharging sand; and at one time
skimming over a field so low as to be able to talk to some laborers.
Pleased as Franklin was with the experiment, he wrote to Henry Laurens that
he yet feared that the machine would hardly become a common carriage in his
time, though, being the easiest of all _voitures_, it would be extremely
convenient to him, now that his malady forbade him the use of the old ones
over a pavement. The idea, however, was such an agreeable one to him that,
when he returned to Philadelphia, he wrote to his friend Jean Baptiste Le
Roy that he sometimes wished that he had brought a balloon from France with
him sufficiently large to raise him from the ground, and to permit him,
without discomfort from his stone, to be led around in his novel conveyance
by a string, attached to it, and held by an attendant on foot.
On the whole, it appeared to Franklin that the invention of the balloon was
a thing of great importance.
Convincing sovereigns of the Folly of Wars [he wrote to
Ingenhousz] may perhaps be one Effect of it; since it
will be impracticable for the most potent of them to
guard his Dominions. Five thousand Balloons, capable of
raising two Men each could not cost more than Five
Ships of the Line; and where is the Prince who can
afford so to cover his Country with Troops for its
Defence, as that Ten Thousand Men descending from the
Clouds might not in many places do an infinite deal of
mischief, before a Force could be brought together to
repel them?
But nothing happened in Franklin's time, nor has happened since, to warrant
the belief that human flying-devices of any sort will ever be free enough
from danger to human life to be a really useful vehicle of transportation
in times of peace. So far their principal value has been during war, when
human safety has little to choose between the earth and the sky, but it is
fair to say that Franklin would have loathed war even more deeply than he
did, if he could have lived to see them in the form of aeroplane or
dirigible, making their way through the air like winged monsters of the
antediluvian past, and dropping devilish agencies of death and desolation
upon helpless innocence, and the fairest monuments of human industry and
art. Poor M. Pilatre de Rozier, whom we have already mentioned, and who was
no less a person than the Professor of Chemistry, at the Athenee Royale, of
which he was the founder, fell with a companion, from an altitude of one
thousand toises to the rocky coast near Boulogne-sur-Mer, and was, as well
as his companion, dashed to pieces. Since his time the discharioted
Phaetons, who have fallen from the upper levels of the atmosphere, even
when not engaged in war, with the same fearful result, have been numerous
enough to constitute a ghastly necrology. Nor, it would appear, was the
peril under the conditions of aerial navigation in its earliest stages
limited to the aeronaut himself. In dissuading Ingenhousz from attempting a
balloon experiment, Franklin said that it was a serious thing to draw out
from their affairs all the inhabitants of a great city and its environs,
and that a disappointment made them angry. At Bordeaux lately, a person,
who pretended to send up a balloon, and had received money from many
people, not being able to make it rise, the populace were so exasperated
that they pulled down his house, and had like to have killed him. Anyone,
who has ever heard the execrations hurled at the head of a baseball umpire
in the United States, when one of his decisions has failed to command
general assent, will experience no difficulty, we are sure, in
understanding the force of the impulse that provoked this outbreak of
Gallic excitement.
The enthusiasm, aroused in Franklin by the balloon, is not more noticeable
than his brooding desire to find some practical use for it. The visionary
speculation, which seeks to take the moon in its teeth, was no part of his
character. He grew no orchids in the air. To use his homely words in a
letter to Charles Thomson, he made no shoes for feet that he had never
measured. Every conclusion, every hypothesis had to be built upon a basis
of patient observation and gradual induction; every invention or discovery
had to have some useful application.
At an earlier period than that of the discovery of the balloon, his
inquisitive spirit had led him to the study of marsh-gas and the pacifying
effect of oil upon troubled waters. In 1764, he had reason to believe that
a friend of his had succeeded in igniting the surface of a river in New
Jersey, after stirring up the mud beneath it, but his scientific friends in
England found it difficult to believe that he had not been imposed upon;
and the Royal Society withheld from publication among its Transactions a
paper on the experiment, written by Dr. Finley, the President of Princeton
College, and read before it. Franklin twice tried it in England without
success, and he prosecuted his investigation with such energy and
persistency that he finally contracted an intermittent fever by bending
over the stagnant water of a deep ditch, and inhaling its foul breath, or,
as would now be said, by being bitten by a mosquito hovering about it.
In 1757, when on one of the ships, bound on Lord Loudon's fool's errand to
Louisburg, he observed that the water in the wake of two of them was
remarkably smooth, while that in the wake of the others was ruffled by the
wind, which was blowing freshly, and, when he spoke of the circumstance to
his captain, the latter answered somewhat contemptuously, as if to a person
ignorant of what everybody else knew, "The cooks have, I suppose, been just
emptying their greasy water through the scuppers, which has greased the
sides of those ships a little." The incident, and what he had read in Pliny
about the practice among the seamen of Pliny's time of calming rough seas
with oil, made him resolve to test the matter by experiment at the first
opportunity. This intention was afterwards strengthened, when he was again
at sea in 1762, by the "wonderful quietness" of oil, resting on the surface
of an agitated bed of water in the glass lamp swinging in his cabin, and by
the supposition of an old sea captain that the phenomenon was in keeping
with the practice, pursued by the Bermudians, of putting oil on water, when
they would strike fish. By the same captain, he was told that he had heard
that fishermen at Lisbon were in the habit of emptying a bottle or two of
oil on the sea, when the breakers on the bar at that port were running too
high for their boats to cross it in safety. From another person, he learnt
that, when divers in the Mediterranean needed more light for their
business, they spewed out from their mouths now and then a small quantity
of oil, which, rising to the surface, smoothed out its refracting waves.
This additional information supplied his curiosity with still further fuel.
It all ended in his dropping a little oil from a cruet on a large pond at
Clapham. The fluid spread with surprising swiftness over the surface, on
which it had fallen; but he found that he had made the mistake of dropping
it on the leeward, instead of the windward, side of the pond. When this
mistake was repaired, and a teaspoonful of oil was poured on its windward
side, where the waves were in an incipient state, and the oil could not be
driven back on the shore, an instant calmness diffused itself over a space
several yards square, which extended gradually until it reached the lee
side of the pond, making all that quarter of it, perhaps half an acre, as
smooth as a looking-glass. After this, he took with him, whenever he went
into the country, a little oil, in the upper hollow joint of his bamboo
cane for the purpose of repeating his experiment, whenever he had a chance
to do so, and, when he did repeat it, it was usually with success.
Far from being so successful, however, was the experiment when, on a
blustering, unpleasant day, he attempted, with the co-operation of Sir
Joseph Banks and other friends, to still the surf on a shore at Portsmouth
with oil poured continually on the sea, at some distance away, through a
hole, somewhat bigger than a goose quill, in the cork of a large stone
bottle, though the effusion did flatten out a considerable tract of the sea
to such an extent that a wherry, making for Portsmouth, seemed to turn into
that tract of choice, and to use it from end to end as a piece of turnpike
road. All this is described by Franklin in a letter to William Brownrigg,
dated November 7, 1773, in which he cited some other illustrations of the
allaying effect of oil on waves besides those that we have mentioned, and
developed the philosophy of the subject with that incomparable clarity of
his, not unlike the action of oil itself in subduing refractions of light.
Now I imagine [he says] that the wind, blowing over
water thus covered with a film of oil, can not easily
_catch_ upon it, so as to raise the first wrinkles, but
slides over it, and leaves it 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
friction, as oil does between those parts of a machine
that would otherwise rub hard together. Hence the oil
dropped on the windward side of a pond proceeds
gradually to leeward, as may be seen by the smoothness
it carries with it, quite to the opposite side. For the
wind being thus prevented from raising the first
wrinkles, that I call the elements of waves, cannot
produce waves, which are to be made by continually
acting upon, and enlarging those elements, and thus the
whole pond is calmed.
And the water in which the Bermudian struck his fish is not more limpid
than these observations suggested by the Portsmouth experiment:
I conceive, that the operation of oil on water is,
first, to prevent the raising of new waves by the wind;
and, secondly, to prevent its pushing those before
raised with such force, and consequently their
continuance of the same repeated height, as they would
have done, if their surface were not oiled. But oil
will not prevent waves being raised by another power,
by a stone, for instance, falling into a still pool;
for they then rise by the mechanical impulse of the
stone, which the greasiness on the surrounding water
cannot lessen or prevent, as it can prevent the winds
catching the surface and raising it into waves. Now
waves once raised, whether by the wind or any other
power, have the same mechanical operation, by which
they continue to rise and fall, as a _pendulum_ will
continue to swing a long time after the force ceases to
act by which the motion was first produced; that motion
will, however, cease in time; but time is necessary.
Therefore, though oil spread on an agitated sea may
weaken the push of the wind on those waves whose
surfaces are covered by it, and so, by receiving less
fresh impulse, they may gradually subside; yet a
considerable time, or a distance through which they
will take time to move, may be necessary to make the
effect sensible on any shore in a diminution of the
surf; for we know, that, when wind ceases suddenly, the
waves it has raised do not as suddenly subside, but
settle gradually, and are not quite down till after the
wind has ceased. So, though we should, by oiling them,
take off the effect of wind on waves already raised, it
is not to be expected that those waves should be
instantly levelled. The motion they have received will,
for some time, continue; and, if the shore is not far
distant, they arrive there so soon, that their effect
upon it will not be visibly diminished.
Nor was it on Clapham Pond and at Portsmouth alone that Franklin, when in
England, tested the tranquillizing properties of oil. He performed the same
experiment on Derwentwater and a small pond near the house of John Smeaton,
the celebrated engineer, at Austhorpe Lodge; and also on a large sheet of
water at the head of the Green Park. And the idea that there was something
almost supernatural about his quick insight and fertility of conception, of
which we find more than one trace in the utterances of his contemporaries,
is suggested in an interesting manner in the account left to us by the Abbe
Morellet of one of these experiments, which he witnessed when Colonel
Barre, Dr. Hawkesworth, David Garrick, Franklin and himself happened to be
guests of Lord Shelburne at Wycombe in 1772.
It is true [the Abbe says] it was not upon the waves of
the sea but upon those of a little stream which flowed
through the park at Wycombe. A fresh breeze was
ruffling the water. Franklin ascended a couple of
hundred paces from the place where we stood, and
simulating the grimaces of a sorcerer, he shook three
times upon the stream a cane which he carried in his
hand. Directly the waves diminished and soon the
surface was smooth as a mirror.
On one occasion, William Small wrote to him from Birmingham that Matthew
Boulton had "astonished the rural philosophers exceedingly by calming the
waves _a la Franklin_."
Struck, when travelling on a canal in Holland, with the statement of a
boatman that their boat was going slow because the season had been a dry
one, and the water in the canal was not as deep as usual, Franklin, by
experiment with a trough and a little boat borrowed for the purpose,
established the fact that the friction caused by the displacement by a
moving boat of shallow water is measurably greater than that caused by the
displacement by such a boat of deeper water. Under like conditions in other
respects, the difference, he concluded, in a distance of four leagues, was
the difference between five and four hours.
A conversation with Captain Folger, of Nantucket, produced far more
important consequences. Influenced by what the captain told him of the
knowledge that the Nantucket whalers had acquired of the retarding effect
of the Gulf Stream upon navigation, Franklin induced him to plat for him
the dimensions, course and swiftness of the stream, and to give him written
directions as to how ships, bound from the Newfoundland Banks to New York,
might avoid it, and at the same time keep clear of certain dangerous banks
and shoals. The immediate object of Franklin was to procure information for
the English Post Office that would enable the mail packets between England
and America to shorten their voyages. At his instance, Captain Folger's
drawing was engraved on the old chart of the Atlantic at Mount and Page's,
Tower Hill, and copies of it were distributed among the captains of the
Falmouth packets. Ever afterwards the Gulf Stream was a favorite field of
investigation to him, when at sea, and its phenomena were mastered by him
with remarkable thoroughness. It was generated, he conjectured, by the
great accumulation of water on the eastern coast of America created by the
trade winds which constantly blew there. He found that it was always warmer
than the sea on each side of it, and that it did not sparkle at night; and
he assigned to its influence the tornadoes, waterspouts and fogs by which
its flow was attended.
Franklin also possessed to a striking degree the inventive capacity which
is such a valuable qualification for experimental philosophy. We have
already seen how ready his mechanical skill was in supplying printing
deficiencies. Speaking of the pulse glasses, made by Nairne, in which water
could be brought to the boiling point with the heat of the hand, he tells
us:
I plac'd one of his glasses, with the elevated end
against this hole (a hole that he had opened through
the wainscot in the seat of his window for the access
of outside air); and the bubbles from the other end,
which was in a warmer situation, were continually
passing day and night, to the no small surprize of even
philosophical spectators.
As he sat in his library at Philadelphia, in his last years, he was
surrounded by various objects conceived by his own ingenuity. The seat of
his chair became a step-ladder, when reversed, and to its arm was fastened
a fan that he could work with a slight motion of his foot. Against his
bookcase rested "the long arm" with which he lifted down the books on its
upper shelves. The hours, minutes and seconds were told for him by a clock,
of his own invention, with only three wheels and two pinions, in which even
James Ferguson, mathematician as he was, had to confess that he experienced
difficulty in making improvements. The very bifocal glasses, now in such
general use, that he wore were a triumph of his own quick wit. Describing
this invention of his in a letter to George Whatley, he said:
I therefore had formerly two Pair of Spectacles, which
I shifted occasionally, as in travelling I sometimes
read, and often wanted to regard the Prospects. Finding
this Change troublesome, and not always sufficiently
ready, I had the Glasses cut, and half of each kind
associated in the same Circle.... By this means, as I
wear my Spectacles constantly, I have only to move my
Eyes up or down, as I want to see distinctly far or
near, the proper Glasses being always ready. This I
find more particularly convenient since my being in
France, the Glasses that serve me best at Table to see
what I eat, not being the best to see the Faces of
those on the other Side of the Table who speak to me;
and when one's Ears are not well accustomed to the
Sounds of a Language, a Sight of the Movements in the
Features of him that speaks helps to explain; so that I
understand French better by the help of my Spectacles.
The shrinking that a mahogany box, given to him in England, underwent, when
subjected to the atmospheric conditions of America, suggested a hygrometer
to him which Nairne afterwards constructed in accordance with his
plans.[55]
His mind seems to have had no torpid moments, except, perhaps, when some
Congressional orator was speaking. When, in early life, he had nothing else
better to do, he would address himself to making magic squares and circles
as intricate as Rosamond's walk. "He took it into his head," James Logan
wrote to Collinson, "to think of _magical squares_, in which he outdid
Frenicle himself, who published above eighty pages in folio on that subject
alone." Not willing to be outdone even by Stifelius, Franklin drew a square
of such extraordinary numerical properties that not only did the numbers on
all the rows and diagonals on its face total 2056, but the sum of the
numbers on every group of 16 smaller squares on its face, when revealed
through a hole in a piece of paper, moved backwards and forwards over its
face, equalled precisely 2056 too. He likewise drew a
magick circle, consisting of 8 concentric circles, and
8 radial rows, filled with a series of numbers, from 12
to 75, inclusive, so disposed as that the numbers of
each circle or each radial row, being added to the
central number 12, they made exactly 360, the number of
degrees in a circle; and this circle had, moreover, all
the properties of the square of 8.
Both of these conceits were duly forwarded to Collinson and, with regard to
the square of 16, Franklin wrote to him playfully that he made no question
but that he would readily allow that it was the most magically magical of
any magic square ever made by any magician. From the terms of this letter,
it is plain that the practical intellect of Franklin was a little ashamed
of these feats as but _difficiles nugae_, but his misgivings were somewhat
soothed by the suggestion of Logan that they might not be altogether
useless if they produced by practice an habitual readiness and exactness in
mathematical disquisitions.
Hardly more profitable than the magic squares but indicative, too, of the
same mental initiative, was the scheme formed by Franklin for a new
alphabet and a reformed mode of spelling. In the new alphabet, the first
effort was to arrange the letters in what was supposed to be a more natural
order than that of the old alphabet by beginning with the simple sounds
framed by the breath with no or very little help from the tongue, teeth
and lips, and proceeding gradually forward from sounds, produced at the
back of the mouth, to the sound produced by closing the lips, that is _m_.
The _c_ of the old alphabet was omitted, _k_ being left to supply its hard
sound, and _s_ its soft, and _k_ being also left to supply the place of
_q_, and with an _s_ added, the place of _x_. _W_ as well as _q_ and _x_
was also dismissed from service, the vowel _u_, sounded as _oo_, being
relied upon to perform its function. _Y_ also went by the board, _i_ taking
its place, where used singly, and two vowels, where used as a diphthong.
_J_ was superseded by an entirely new symbol, shaped something like a small
_h_, and sounded as _ish_, when used singly, but subserving various other
offices, when conjoined with _d_, _t_ and _z_. As a whole, the new alphabet
was so systematized that the sound of any letter, vowel or consonant was
always the same, wherever it occurred, or whatever its alphabetical
collocation. Nor did the new alphabet contain any silent letters, or fail
to provide a letter for every distinct sound in the language. The
difference between short and long vowels was compassed by a single vowel
where short, and a double one, where long. For illustration, "mend"
remained "mend" and "did," "did," but "remained" reappeared as "remeened,"
and "deed" as "diid." Typographical obstacles prevent us from bringing to
the eye of the reader a specimen of the reformed alphabet and spelling as
they looked on a printed page. They, of course, issued from the mind of
Franklin as stillborn as his reformed Episcopal Prayer Book. His only
proselytes appear to have been Polly, who even wrote a letter to him in the
strange forms, and his loving sister, Jane, who was delighted to have
another language with which to express her affection for him. Our world is
one in which some things are made but others make themselves, and, however
arbitrary their character, will not allow themselves to be made over, even
at the behest of such merciless rationalism as that of Franklin.
In the latter part of Franklin's life, Noah Webster, the lexicographer,
also formed a scheme for the reform of the alphabet, and Franklin had the
pleasure of writing to him, "Our Ideas are so nearly similar, that I make
no doubt of our easily agreeing on the Plan." Several years later, Webster,
in his _Dissertations on the English Language_, stated that Franklin had
compiled a dictionary, based upon his own reformatory system, and procured
the types for printing it, but, finding himself too old to prosecute his
design, had offered both manuscript and types to him. "Whether this
project, so deeply interesting to this country," Webster said, "will ever
be effected; or whether it will be defeated by insolence and prejudice,
remains for my countrymen to determine."
Another thing upon which the ingenuity of Franklin was brought to bear, as
the reader has already been told, was the Armonica. In his letter to
Beccaria, extolling its merits, he describes it with a wealth of detail,
not only thoroughly in keeping with his knack for mechanics, but showing
that to music as to everything else, that won the favor of his intellect,
he brought the ken of a man of science. The letter concludes with a dulcet
compliment, which harmonizes well with its subject: "In honour of your
musical language (the Italian), I have borrowed from it the name of this
instrument, calling it the Armonica." In one of his papers, he drew up
instructions for the proper use of the instrument which nothing but the
most intimate familiarity with its operation could have rendered possible.
Admiration has often been expended upon the acuteness with which Franklin,
in a letter to Lord Kames, accounted for the pleasure afforded by the old
Scotch tunes, as compared with the pleasure afforded by the difficult music
of his day, which, he said, was of the same nature as that awakened by the
feats of tumblers and rope-dancers. The reason was this. The old Scotch
melodies were composed by the minstrels of former days, to be played on the
harp, accompanied by the voice. The harp was strung with wire (which gives
a sound of long continuance) and had no contrivance like that in the modern
harpsichord, by which the sound of the preceding note could be stopped, the
moment a succeeding note began. To avoid _actual_ discord, it was therefore
necessary that the succeeding emphatic note should be a chord with the
preceding, as their sounds must exist at the same time. Hence arose that
beauty in those tones that had so long pleased, and would please forever,
though men scarce knew why.
The most useful invention of Franklin was what came to be known as the
Franklin stove. With modifications, it is still in use, and the essay
written on it by Franklin, entitled _An Account of the New-invented
Pennsylvanian Fireplaces_, is one of the best illustrations of the capacity
of his scientific genius to adapt itself to the hardest and barest offices
that human comfort and convenience could impose upon it with a nicety and
accuracy of trained insight and touch worthy of the cleverest journeyman, a
command of scientific principles to be expected only of a professional
student, and a gift of clear, lively expression which reminds us of the
remark of Stella that Dean Swift could write agreeably even about a
broomstick. The principle upon which the Franklin stove was constructed was
that of making the heat from its open fireplace, after first ascending to
its top, descend in such a manner at its back, before passing off into the
chimney, as to diffuse by radiation through the room, in which it stood, a
large part of its warmth. The essay enumerates the different methods of
heating rooms then in use: the great, open, smoky chimney-place, that the
unremitting labor of one man could scarce keep supplied with fuel, and that
gave out little more heat for human warmth than a fire outdoors; this
chimney-place reduced to a smaller size with jambs, and free, to a great
extent from the reproach of smokiness, yet, with its contraction setting up
strong currents of whistling and howling air, which reminded Franklin of
the Spanish proverb,
"If the Wind blows on you thro' a Hole,
Make your Will, and take Care of your Soul";
the expensive and intricate French fireplaces with hollow backs, hearths
and jambs of iron; the Holland stove, which shut off the sight of the fire,
and could not conveniently be used for any purposes except those of warmth;
the German stove which was subject to very much the same disadvantages as
the Holland stove; and charcoal fires in pots which emitted disagreeable
and dangerous fumes and were used chiefly in the shops of handicraftsmen.
From the shortcomings of all these methods of heating rooms, the Franklin
stove, its inventor contended, was exempt. It diffused heat equally
throughout a whole room; if you sat in an apartment warmed by it, you were
not scorched before, while you were frozen behind; nor were you exposed to
the drafts from which so many women, particularly, got colds in the head,
rheums and defluxions that fell upon their jaws and gums, and destroyed
early many a fine set of teeth in the northern colonies, and from which so
many persons of both sexes contracted coughs, catarrhs, toothaches, fevers,
pleurisies and other diseases. It kept a sick room supplied with a fresh
and yet properly tempered flow of pure air. It conserved heat. It
economized fuel. With it, Franklin said, he could make his room twice as
warm as it used to be with a quarter of the wood that he used to consume.
If you burned candles near it, they did not flare and run off into tallow
as in the case of ordinary fireplaces with their excessive drafts. It
corrected most smoky chimneys. It prevented all kinds of chimneys from
fouling, and if they fouled made them less likely to fire, and, if they
fired, made the fire easier to repress. A flame could be speedily kindled
in it with the help of the shutter or trap-bellows that went along with
it. A fire could be readily extinguished in it, or could be so secured in
it that not one spark could fly out of it to do any damage. A room once
warmed remained warm all night. "With all these Conveniences," concludes
Franklin, "you do not lose the pleasing Sight nor Use of the Fire, as in
the Dutch Stoves, but may boil the Tea-Kettle, warm the Flat-Irons, heat
Heaters, keep warm a Dish of Victuals by setting it on the Top, &c. &c."
Some years after the publication of this essay, Franklin devised an
improvement in the open chimney-place which tended to abate drafts and
check the escape of heat up the chimney by contracting the chimney opening,
bringing its breast down to within three feet of the hearth, and placing an
iron frame just under this breast, with grooves on each side of the frame,
in which an iron plate could be slid backwards and forwards at pleasure,
for the purpose of cutting off the mouth of the chimney entirely from the
chimney itself, when there was no fire on the hearth, or of leaving a space
of not more than two inches for the escape of smoke between the further
edge of the plate and the back of the chimney-mouth. This improved
chimney-place was described by Franklin in letters to Alexander Dick and
James Bowdoin. The letter to Bowdoin seems to leave little to be said on
the subject of chimneys. It indicates that Franklin had subjected them to a
scrutiny hardly less close than that which he had fixed upon the Leyden
Jar. In connection with the currents and reverse currents, set up in them
in summer by the relations of inequality, which the air in them sustains,
at different hours of the day and night, to the outside temperature, he
suggests that joints of meat might keep for a week or more during the
hottest weather in chimney-openings, if well wrapt three or four fold in
wet linen cloths, sprinkled once a day with water to prevent evaporation.
Butter and milk in vessels and bottles covered with wet cloths might, he
thought, be preserved in the same way. And he even thought, too, that the
movements of air in chimneys might, with the aid of smoke-jack vanes, be
applied to some mechanical purposes, where a small but pretty constant
power only was needed. To appreciate how patiently and exhaustively
Franklin was in the habit of pursuing every course of observation or
reflection opened up by his scientific propensities, the whole of this
letter, which had much more to say on the subject of chimneys than we have
mentioned, should be read.
At a later period of his life, Franklin describes to Turgot what he called
his new stove. The novel feature of this consisted of an aerial syphon by
which the smoke from the fireplace of the stove was first drawn upwards
through the longer leg of the syphon, and then downwards through its
shorter leg, and over burning coals, by which it was kindled into flame and
consumed.
The ingenuity of Franklin was also exerted very successfully in the
rectification of smoky chimneys. In his essay on the causes and cure of
such chimneys, written on his last ocean voyage, he resolved the causes
into no less than nine heads, and stated with his accustomed perspicuity
and precision the remedy for each cause. In his time, the art of properly
carrying off smoke through chimneys was but imperfectly understood by
ordinary builders and mechanics, and it was of too humble a nature to tempt
discussion by such men of science as were capable of clearly expounding the
physical principles upon which it rested. It was not strange, therefore,
that Franklin, who deemed nothing, that was useful, to be beneath the
dignity of philosophy, should have acquired in his time the reputation of
being a kind of "universal smoke doctor" and should have been occasionally
consulted by friends of his, such as Lord Kames, about refractory chimneys.
The only smoky chimney, that seems to have completely baffled his
investigation, recalls in a way the philosopher, who thought that he had
discovered a new planet, but afterwards found that what he saw was only a
fly in the end of his telescope. After exhausting every scientific resource
in an effort to ascertain why the chimney in the country-house of one of
his English friends smoked, Franklin was obliged to own the impotence for
once of his skill; but, subsequently, his friend, who made no pretensions
to the character of a fumist, climbed to the top of the funnel of his
chimney by a ladder, and, on peering down into it, found that it had been
filled by nesting birds with twigs and straw, cemented with clay, and lined
with feathers.
Nor was the attention given by Franklin to ventilation by any means
confined to chimneys. Air vitiated by human respiration also came in for a
share of it. Describing an experiment by which he demonstrated the manner
in which air affected in this way is purified, Alexander Small said:
The Doctor confirmed this by the following experiment.
He breathed gently through a tube into a deep glass
mug, so as to impregnate all the air in the mug with
this quality. He then put a lighted bougie into the
mug; and upon touching the air therein the flame was
instantly extinguished; by frequently repeating the
operation, the bougie gradually preserved its light
longer in the mug, so as in a short time to retain it
to the bottom of it; the air having totally lost the
bad quality it had contracted from the breath blown
into it.
Franklin became deeply interested in the brilliant course of investigation
pursued by Priestley with respect to gases, and several penetrating glances
of his into the relations of carbonic acid gas to vegetation have come down
to us. Observing on a visit to Priestley the luxuriance of some mint
growing in noxious air, he suggested to Priestley that "the air is mended
by taking something from it, and not by adding to it." He hoped, he said in
a letter to Priestley, that the nutriment derived by vegetation from
carbonic acid gas would give some check to the rage of destroying trees
that grew near houses, which had accompanied recent improvements in
gardening from an opinion of their being unwholesome.
Just as he was consulted about the best methods of protecting St. Paul's
Cathedral and the arsenals at Purfleet from lightning, so he was also
consulted by the British Government as to the best method for ventilating
the House of Commons. "The personal atmosphere surrounding the members," he
thought, "might be carried off by making outlets in perpendicular parts of
the seats, through which the air might be drawn off by ventilators, so
placed, as to accomplish this without admitting any by the same channels."
The experiment might be tried upon some of our City Councilmen. Principles
of ventilation, expounded by Franklin, were also utilized by the Messrs.
Adam of the Adelphi, in the construction of the large room built by them
for the meetings of the Society for the Encouragement of Arts. We also find
him suggesting openings, close to the ceilings of rooms, and communicating
with flues, constructed alongside of chimney flues, as effective means for
ventilating rooms.
With all his primary and secondary gifts for scientific research, it is
difficult to believe that, if Franklin had not been diverted from it by
engrossing political cares, he would have added both to his special
reputation as a student of electricity and to his general reputation as a
man of science. As it was, his civic activity and popular leadership in
Pennsylvania, his several agencies abroad, his participation in the
American Revolution, his career as Minister to France, and his official
duties, after his return, made such imperious demands upon his time that he
had little or no leisure left for scientific pursuits. This picture of his
situation which he presented in a letter to Ingenhousz, when he was in
France, was more or less true of almost every part of his life after he
became famous:
Besides being harass'd with too much Business, I am
expos'd to numberless Visits, some of Kindness and
Civility, many of mere idle Curiosity, from Strangers
of America & of different Parts of Europe, as well as
the Inhabitants of the Provinces who come to Paris.
These devour my Hours, and break my Attention, and at
Night I often find myself fatigu'd without having done
anything. Celebrity may for a while flatter one's
Vanity, but its Effects are troublesome. I have begun
to write two or three Things, which I wish to finish
before I die; but I sometimes doubt the possibility.
Some of the reflections of Franklin on scientific subjects, such as his
early letters to Cadwallader Colden with regard to "perspirants and
absorbents" are, to use his own expression in one of them, too plainly
_ultra crepidam_ to have any value. Of others, we might fairly say that his
knowledge of the topics which he handled in them was hardly deep enough to
deserve any praise more confident than that which he allowed himself when
writing to Cadwallader Colden in 1751 of the Philadelphia Experiments.
"So," he said to Colden in this letter, "we are got beyond the skill of
_Rabelais's_ devils of two years old, who, he humorously says, had only
learnt to thunder and lighten a little round the head of a cabbage." All
the same, even aside from his electrical experiments, Franklin acquired no
little fame as a philosopher, made more than one fruitful suggestion to
fellow-workers of his in the domain of science and contributed many useful
observations to the general fund of scientific thought.
Apparently his views on medical topics were held in very considerable
respect. In 1777, he was elected a member of the Royal Medical Society of
Paris, and in 1787 an honorary member of the Medical Society of London.
Many works on medical subjects were dedicated to him by their authors. He
was one of the commission which exposed the imposture of Mesmer. There are
few things that give us a better idea of the extraordinary celebrity
enjoyed by him than the wide currency obtained by a spurious opinion of
his, ascribing great merit to tobacco ashes as a remedy for dropsy. It won
such an extensive circulation, and brought down on his head such a flood of
questions from physicians and others, that he was compelled to deny flatly
the truth of the story. One person, Lord Cadross, afterwards the Earl of
Buchan, firmly believed that he would have perished at the hands of a
professional physician, who wished to blister him, when he was afflicted
with a fever, if Franklin had not dissented from the treatment. Franklin
probably deserved no higher credit for his dissent on this occasion than
that of sharing the opinion of Sir John Pringle, who was convinced that,
out of every one hundred fevers, ninety-two cured themselves. So far as we
can see, there is nothing in the works of Franklin to warrant the belief
that he possessed any uncommon degree of medical knowledge, though he was
full of curiosity with regard to medicine as with regard to every other
branch of human learning. In one of his letters to Colden, written in his
fortieth year, he expressed the hope that future experiment would confirm
the idea that the yaws could be cured by tar-water. In a later letter to
Colden, he expressed his pleasure at hearing more instances of the success
of the poke-weed "in the Cure of that horrible Evil to the human Body, a
Cancer." At his suggestion, a young physician, with the aid of Sanctorius'
balance, tested alternately each hour, for eight hours, the amount of the
perspiration from his body, when naked, and when warmly clad, and found
that it was almost as great during the hours when he was naked. By his
investigations into the malady known in his time popularly as "the dry
bellyache," and learnedly as the "_colica Pictonum_," he conferred a real
benefit upon medical science. His views upon the subject received the honor
of being incorporated with due acknowledgments into Dr. John Hunter's essay
on the _Dry Bellyache of the Tropics_. Summarily speaking they were that
the complaint was a form of lead poisoning.
I have long been of opinion [he wrote to Dr.
Cadwallader Evans in 1768] that that distemper proceeds
always from a metallic cause only; observing that it
affects, among tradesmen, those that use lead, however
different their trades,--as glaziers, letter-founders,
plumbers, potters, white-lead makers, and painters;...
although the worms of stills ought to be of pure tin,
they are often made of pewter, which has a great
mixture in it of lead.
The year before this letter was written, Franklin had found on reading a
pamphlet, containing the names and vocations of the persons, who had been
cured of the colic at Charite, a Parisian hospital, that all of them had
followed trades, which handle lead in some form or other. On going over the
vocations, he was at first puzzled to understand why there should be any
stonecutters or soldiers among the sufferers, but his perplexity was
cleared up by a physician at the hospital, who informed him that
stonecutters frequently used melted lead for fixing the ends of iron
balustrades in stone, and that the soldiers had been employed as laborers
by painters, when grinding colors. These facts were long afterwards
communicated by Franklin to Benjamin Vaughan in a letter, in which he cited
other incidents, interesting partly because they corroborated his theory,
and partly because they are additional proofs of his vigilance and patience
in collecting facts, before advancing an hypothesis, as well as of a
memory, which retained every instructive circumstance imparted to it by eye
or ear as imperishably as hardening cement retains the impression of a
dog's foot. When he was a boy at Boston, Franklin said, it was discovered
that New England rum, which had produced the dry bellyache and paralyzed
the limbs in North Carolina, had been made by distilleries with leaden
still-heads and worms. Later, when he was in London, he had been warned by
an old workman at Palmer's printing-house, as well as by an obscure pain in
his own hands, that it was a dangerous practice to handle a heated case of
types. About the same time, a letter-founder in the same close at Palmer's,
in a conversation with him, ascribed the existence of the ailment among his
workmen to the fact that some of them were slovenly enough to go to their
meals with unwashed hands that had come into contact with molten lead. He
had also observed in Derbyshire that the smoke from lead furnaces was
pernicious to grass and other vegetables, and in America had often observed
that streaks on shingle roofs, made by white lead, washed from balusters or
dormer window frames, were always entirely free from moss. He had also been
told of a case where this colic had afflicted a whole family, and was
supposed to be due to the corrosive effect of the acid in leaves, shed upon
the roof, from which the family derived the supply of rain water, upon
which it relied for drink.
More important still than the insight that Franklin obtained into the
Painter's Colic was the insight which he obtained into the salutary effect
of the custom which is now almost universal, except in the homes of the
ignorant and squalid, of sleeping at night in rooms with the windows up.
This custom, as well as the outdoor regimen, which has proved of such
signal value in the treatment of tuberculosis, originated in hygienic
conceptions identical with those steadfastly inculcated by him. His
opinions with regard to colds and the benefits of pure air were expressed
at many different times, and in many different forms, but nowhere so
conveniently for the purposes of quotation as in a letter which he wrote to
Dr. Benjamin Rush in 1773.
I hope [he said in this letter] 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 frouzy,
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 bedclothes,
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 English have called _colds_.
As to Dr. Cullen's cold or catarrh _a frigore_, I
question whether such an 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 could 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.
Franklin's belief that colds and overeating often went hand in hand also
found expression in one of his letters to Polly Stevenson. When sending
her an account of some seamen, who had experienced considerable relief from
thirst by wearing clothes kept constantly wet with salt water, he said, "I
need not point out to you an Observation in favour of our Doctrine, that
you will make on reading this Paper, that, _having little to eat_, these
poor People in wet Clothes Day and Night _caught no cold_." In every, or in
practically every, case, he seems to have referred colds to what he rather
vaguely calls a siziness and thickness of the blood, resulting from checked
perspiration, produced by different agencies, including a gross diet.
Thus [he says in his _Notes and Hints for Writing a
Paper Concerning what is called Catching Cold_], People
in Rooms heated by a Multitude of People, find their
own Bodies heated; thence the quantity of perspirable
Matter is increased that should be discharged, but the
Air, not being changed, grows so full of the same
Matter, that it will receive no more. So the Body must
retain it. The Consequence is, the next Day, perhaps
sooner, a slight putrid Fever comes on, with all the
Marks of what we call a Cold, and the Disorder is
suppos'd to be got by coming out of a warm Room,
whereas it was really taken while in that Room.
He did not shrink from any of the consequences of his reasoning about colds
however extreme.
Be so kind as to tell me at your leisure [he wrote to
Barbeu Dubourg], whether in France, you have a general
Belief that moist Air, and cold Air, and damp Shirts or
Sheets, and wet Floors, and Beds that have not lately
been used, and Clothes that have not been lately worn,
and going out of a warm Room into the Air, and leaving
off a long-worn Wastecoat, and wearing leaky Shoes, and
sitting near an Open Window, or Door, or in a Coach
with both Glasses down, are all or any of them capable
of giving the Distemper we call _a Cold_, and you _a
Rheum, or Catarrh_? Or are these merely _English_
ideas?
His views on the wholesomeness of fresh air were far in advance of the
general intelligence of his time, and were expressed in spirited terms.
After stating in a letter to Jean Baptiste Le Roy that he had become
convinced that the idea that perspiration is checked by cold was an error
as well as the idea that rheum is occasioned by cold, he added:
But as this is Heresy here, and perhaps may be so with
you, I only whisper it, and expect you will keep my
Secret. Our Physicians have begun to discover that
fresh Air is good for People in the Small-pox & other
Fevers. I hope in time they will find out that it does
no harm to People in Health.
At times his language on what he called _aerophobia_ grew highly animated.
What Caution against Air [he said in a letter to Thomas
Percival], what stopping of Crevices, what wrapping up
in warm Clothes, what shutting 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 Hide Park, with the Glasses
both up close, all breathing over & over again the same
Air they brought out of Town with them in the Coach
with the least change possible, and render'd worse and
worse every moment. And this they call _taking the
Air_.
Indeed, there is at times something just a little ludicrous in the
uncompromising fervor with which Franklin insisted upon his proposition. It
seemed strange he said, in the letter from which we have just quoted, that
a man whose body was composed in great part of moist fluids, whose blood
and juices were so watery, and who could 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.
It is a delightful account that John Adams gives us of a night which he
spent in the same bed with Franklin at New Brunswick, on their way to the
conference with Lord Howe:
The chamber [Adams tells us] was little larger than the
bed, without a chimney, and with only one small window.
The window was open, and I, who was an invalid, and
afraid of the air in the night, shut it close. "Oh!"
says Franklin, "don't shut the window, we shall be
suffocated." I answered I was afraid of the evening
air. Dr. Franklin replied, "The air within this chamber
will soon be, and indeed is now, worse than that
without doors. Come, open the window and come to bed,
and I will convince you. I believe you are not
acquainted with my theory of colds." Opening the window
and leaping into bed, I said I had read his letters to
Dr. Cooper, in which he had advanced that nobody ever
got cold by going into a cold church or any other cold
air, but the theory was so little consistent with my
experience, that I thought it a paradox. However, I had
so much curiosity to hear his reasons, that I would run
the risk of a cold. The Doctor then began a harangue
upon air and cold, and respiration and perspiration,
with which I was so much amused that I soon fell
asleep, and left him and his philosophy together; but I
believe they were equally sound and insensible within a
few minutes after me, for the last words I heard were
pronounced as if he was more than half asleep. I
remember little of the lecture, except that the human
body, by respiration and perspiration, destroys a
gallon of air in a minute; that two such persons as we
were now in that chamber would consume all the air in
it in an hour or two; that by breathing over again the
matter thrown off by the lungs and the skin, we should
imbibe the real cause of colds, not from abroad, but
from within.
At times Franklin merely gave hints to brother philosophers and left them
to run the hints down. For instance, he suggested to M. De Saussure, of
Geneva, who succeeded in ascending Mont Blanc, the idea of ascertaining
the lateral attraction of the Jura Mountains for the purpose of discovering
the mean density of the earth upon the Newtonian theory of gravitation.
This was subsequently done with complete success by Nevil Maskelyne on Mt.
Schehallion in Perthshire. To Ingenhousz he suggested the idea of "hanging
a weight on a spiral spring, to discover if bodies gravitated differently
to the earth during the conjunctions of the sun and moon, compared with
other times."
He gave very close study to the philosophy of waterspouts and whirlwinds
and came to the conclusion that they were generated by the same causes, and
were of the same nature, "the only Difference between them being, that the
one passes over Land, the other over Water." He was the first person to
discover that northeast storms did not begin in the northeast at all. The
manner in which he did it is another good illustration of his quickness in
noting the significance of every fact by which his attention was
challenged. He desired to observe a lunar eclipse at nine o'clock in the
evening at Philadelphia, but his efforts were frustrated by a northeast
storm, which lasted for a night and a day, and did much damage all along
the Atlantic coast. To his surprise he afterwards learnt from the Boston
newspapers that the eclipse had been visible there, and, upon writing to
his brother for particulars, was informed by him that it had been over for
an hour when the storm set in at Boston; though it was apparently fair to
assume that the storm began sooner at Boston than at Philadelphia. This
information and further inquiry satisfied him that northeast storms
commence southward and work their way to the northeast at the rate of a
hundred miles an hour. When we read the words in which he stated his theory
of such storms, we begin to understand what Sir Humphry Davy meant in
saying that science appeared in Franklin's language in a dress wonderfully
decorous, and best adapted to display her native loveliness.
Suppose [he said to Jared Eliot] a great tract of
country, land and sea, to wit, Florida and the Bay of
Mexico, to have clear weather for several days, and to
be heated by the sun, and its air thereby exceedingly
rarefied. Suppose the country northeastward, as
Pennsylvania, New England, Nova Scotia, and
Newfoundland, to be at the same time covered with
clouds, and its air chilled and condensed. The rarefied
air being lighter must rise, and the denser air next to
it will press into its place; that will be followed by
the next denser air, that by the next, and so on. Thus,
when I have a fire in my chimney, there is a current of
air constantly flowing from the door to the chimney;
but the beginning of the motion was at the chimney,
where the air being rarefied by the fire rising, its
place was supplied by the cooler air that was next to
it, and the place of that by the next, and so on to the
door. So the water in a long sluice or mill-race, being
stopped by a gate, is at rest like the air in a calm;
but as soon as you open the gate at one end to let it
out, the water next the gate begins first to move, that
which is next to it follows; and so, though the water
proceeds forward to the gate, the motion which began
there runs backward, if one may so speak, to the upper
end of the race, where the water is last in motion.
It may be truly said of every province of scientific research into which
Franklin ventured that he brought to it a bold and original spirit of
speculation which gave it new interest and meaning. Even when he was not
the first to kindle a light, he had a happy and effective way of trimming
it anew and freshening its radiance. To Collinson he wrote on one occasion,
"But I must own I am much in the _Dark_ about _Light_." But noonday is not
more luminous than what he had to say on the subject in this letter.
May not all the Phaenomena of Light [he asked] be more
conveniently solved, by supposing universal Space
filled with a subtle elastic Fluid, which, when at
rest, is not visible, but whose Vibrations affect that
fine Sense the Eye, as those of Air do the grosser
Organs of the Ear? We do not, in the Case of Sound,
imagine that any sonorous Particles are thrown off from
a Bell, for Instance, and fly in strait Lines to the
Ear; why must we believe that luminous Particles leave
the Sun and proceed to the Eye? Some Diamonds, if
rubbed, shine in the Dark, without losing any Part of
their Matter. I can make an Electrical Spark as big as
the Flame of a Candle, much brighter, and, therefore,
visible farther, yet this is without Fuel; and, I am
persuaded no part of the Electric Fluid flies off in
such Case to distant Places, but all goes directly, and
is to be found in the Place to which I destine it. May
not different Degrees of Vibration of the
above-mentioned Universal Medium occasion the
Appearances of different Colours? I think the Electric
Fluid is always the same; yet I find that weaker and
stronger Sparks differ in apparent Colour; some white,
blue, purple, red; the strongest, White; weak ones,
red. Thus different Degrees of Vibration given to the
Air produce the 7 different Sounds in Music, analagous
to the 7 Colours, yet the Medium, Air, is the same.
"Universal Space, as far as we know of it," he declared in his _Loose
Thoughts on a Universal Fluid_, "seems to be filled with a subtil Fluid,
whose Motion, or Vibration is called Light." And he then proceeds to found
on this statement a series of speculations marked by too high a degree of
temerity to have much scientific value. One sentiment in the paper,
however, is well worth recalling as showing how clearly its author had
grasped the conservation of matter. "The Power of Man relative to Matter,"
he observed, "seems limited to the dividing it, or mixing the various kinds
of it, or changing its Form and Appearance by different Compositions of it;
but does not extend to the making or creating of new Matter, or
annihilating the old."
The Science of Palaeontology was in its infancy during the lifetime of
Franklin. Many years before Cuvier gave the name of mastodon to the
prehistoric beast, whose fossil remains had been brought to sight from time
to time in different parts of the world, George Croghan, the Indian trader,
sent to Franklin a box of tusks and grinders, which had been found near the
Ohio, and which he supposed to be parts of a dismembered elephant. In his
reply of thanks, Franklin observed that the tusks were nearly of the same
form and texture as those of the African and Asiatic elephant. "But the
grinders differ," he added, "being full of knobs, like the grinders of a
carnivorous animal; when those of the elephant, who eats only vegetables,
are almost smooth. But then we know of no other animal with tusks like an
elephant, to whom such grinders might belong." The fact that, while
elephants inhabited hot countries only, fragments such as those sent to him
by Croghan were found in climates like those of the Ohio Territory and
Siberia, looked, Franklin concluded, "as if the earth had anciently been in
another position, and the climates differently placed from what they are at
present." Contrasting the observations of this letter with the paper read
long afterwards by Thomas Jefferson before the American Philosophical
Society on the bones of a large prehistoric quadruped resembling the sloth,
William B. Scott, the American palaeontologist, remarks:
Franklin's opinions are nearer to our present beliefs
than were Jefferson's, written nearly forty years
later. Of course, we now know that Franklin was
mistaken in supposing that such bones were found only
in what is now Kentucky and in Peru, and his comparison
of the teeth of the mastodon with the "grinders of a
carnivorous animal" is not very happy, but the
inferences are remarkably sound, when we consider the
state of geological knowledge in 1767.
In a letter to Antoine Court de Gebelin, the author of the _Monde
Primitif_, Franklin gave him a valuable caution, in relation to apparent
linguistic variations. Strangers, who learnt the language of an Indian
nation, he said, finding no orthography, formed each his own orthography
according to the usual sounds given to the letters in his own language.
Thus the same words of the Mohawk language, written by an English, a French
and a German interpreter, often differed very much in the spelling.
Franklin's letters to Herschel, Maskelyne, Rittenhouse, Humphrey Marshall
and James Bowdoin reveal a keen interest in astronomy, but this is not one
of the fields from which he came off _cum laude_. Gratifying to the pride
of an American, however, is an observation which he made to William
Herschel, when the latter sent to him for the American Philosophical
Society a catalogue of one thousand new nebulae and star-clusters and stated
at the same time that he had discovered two satellites, which revolved
about the Georgian planet. In congratulating him on the discovery, Franklin
said:
You have wonderfully extended the Power of human
Vision, and are daily making us Acquainted with Regions
of the Universe totally unknown to mankind in former
Ages. Had Fortune plac'd you in this part of America,
your Progress in these Discoveries might have been
still more rapid, as from the more frequent clearness
of our Air, we have near one Third more in the year of
good observing Days than there are in England.
The production of cold by evaporation was another subject which enlisted
the eager interest of Franklin. In co-operation with Dr. Hadley, the
Professor of Chemistry at Cambridge, England, he was so successful in
covering a ball with ice by wetting it from time to time with ether, and
blowing upon the ether with a bellows, that he could write to John Lining
in these words: "From this experiment one may see the possibility of
freezing a man to death on a warm summer's day, if he were to stand in a
passage through which the wind blew briskly, and to be wet frequently with
ether, a spirit that is more inflammable than brandy, or common spirits of
wine."
Geology was in its infancy during Franklin's time, but he hazarded some
conjectures about the formation of the earth that are perhaps not less
trustworthy than those advanced by riper geologists. In the letter, in
which these conjectures were communicated to the Abbe Soulavie, he said:
Part of the high county of Derby being probably as much
above the level of the sea, as the coal mines of
Whitehaven were below it, seemed a proof that there had
been a great _bouleversement_ in the surface of that
Island (Great Britain), some part of it having been
depressed under the sea, and other parts which had been
under it being raised above it.... Such changes in the
superficial parts of the globe [he continued] seemed to
me unlikely to happen if the earth were solid to the
centre. I therefore imagined that the internal parts
might be a fluid more dense, and of greater specific
gravity than any of the solids we are acquainted with;
which therefore might swim in or upon that fluid. Thus
the surface of the globe would be a shell, capable of
being broken and disordered by the violent movements of
the fluid on which it rested.
The letter contains other speculations equally bold:
It has long been a supposition of mine that the iron
contained in the substance of this globe, has made it
capable of becoming as it is a great magnet. That the
fluid of magnetism exists perhaps in all space; so that
there is a magnetical North and South of the universe
as well as of this globe, and that if it were possible
for a man to fly from star to star, he might govern his
course by the compass. That it was by the power of this
general magnetism this globe became a particular
magnet. In soft or hot iron the fluid of magnetism is
naturally diffused equally; when within the influence
of the magnet, it is drawn to one end of the Iron, made
denser there, and rare at the other, while the iron
continues soft and hot, it is only a temporary magnet:
If it cools or grows hard in that situation, it becomes
a permanent one, the magnetic fluid not easily resuming
its equilibrium. Perhaps it may be owing to the
permanent magnetism of this globe, which it had not at
first, that its axis is at present kept parallel to
itself, and not liable to the changes it formerly
suffered, which occasioned the rupture of its shell,
the submersions and emersions of its lands and the
confusion of its seasons.
It was probably, Franklin thought, different relations between the earth
and its axis in the past that caused much of Europe, including the
mountains of Passy, on which he lived, and which were composed of limestone
rock and sea shells, to be abandoned by the sea, and to change its ancient
climate, which seemed, he said, to have been a hot one.
The physical convulsions to which the earth had been subject in the past
were, however, in his opinion beneficent.
Had [he said in a letter to Sir John Pringle] the
different strata of clay, gravel, marble, coals,
limestone, sand, minerals, &c., continued to lie level,
one under the other, as they may be supposed to have
done before these convulsions, we should have had the
use only of a few of the uppermost of the strata, the
others lying too deep and too difficult to be come at;
but the shell of the earth being broke, and the
fragments thrown into this oblique position, the
disjointed ends of a great number of strata of
different kinds are brought up to-day, and a great
variety of useful materials put into our power, which
would otherwise have remained eternally concealed from
us. So that what has been usually looked upon as a
_ruin_ suffered by this part of the universe, was, in
reality, only a preparation or means of rendering the
earth more fit for use, more capable of being to
mankind a convenient and comfortable habitation.
The scientific conjectures of Franklin may not always have been sound, but
they are invariably so readable that we experience no difficulty in
understanding why the Abbe Raynal should have preferred his fictions to
other men's truths.
FOOTNOTES:
[51] The lightning rod in its origin encountered the same religious
misgivings as inoculation and insurance and many other ideas which have
promoted human progress and happiness. The Rev. Thomas Prince at the time
of the Lisbon earthquake thought that the more lightning rods there were
the greater was the danger that the earth might become perilously
surcharged with electricity. "In Boston," he said, "are more erected than
anywhere else in New England; and Boston seems to be more dreadfully
shaken. Oh! there is no getting out of the Mighty Hand of God! If we think
to avoid it in the Air we can not in the Earth. Yea, it may grow more
fatal."
[52] The lines under the portrait of Franklin by Cochin do not hesitate to
exalt him above the most powerful forces of Nature and the authority of the
Gods:
"C'est l'honneur et l'appui du nouvel hemisphere,
Les flots de l'Ocean s'abaissent a sa voix;
Il reprime ou dirige a son gre le tonnerre.
Qui desarme les dieux peut-il craindre les rois?"
[53] "With Franklin grasp the lightning's fiery wing," is a line in Thomas
Campbell's _Pleasures of Hope_. In his _Age of Bronze_, Byron asks in one
place why the Atlantic should "gird a tyrant's grave"
"While Franklin's quiet memory climbs to heaven,
Calming the lightning which he thence hath riven."
And in another place in the same poem he speaks of
"Stoic Franklin's energetic shade,
Robed in the lightnings which his hand allayed."
Crabbe in his tribute to "Divine Philosophy" in the _Library_ exclaims,
"'Tis hers the lightning from the clouds to call,
And teach the fiery mischief where to fall."
[54] The inductive process by which Franklin arrived at the identity of
lightning and electricity was set forth in one of his letters to John
Lining, of Charleston, dated March 18, 1755. The minutes kept by him of his
experiments and observations, contained, he said, the following entry:
"November 7, 1749. Electrical fluid agrees with lightning in these
particulars. 1. Giving light. 2. Colour of the light. 3. Crooked direction.
4. Swift motion. 5. Being conducted by metals. 6. Crack or noise in
exploding. 7. Subsisting in water or ice. 8. Rending bodies it passes
through. 9. Destroying animals. 10. Melting metals. 11. Firing inflammable
substances. 12. Sulphureous smell. The electric fluid is attracted by
points. We do not know whether this property is in lightning. But since
they agree in all particulars wherein we can already compare them, is it
not probable they agree likewise in this? Let the Experiment be made."
[55] The standing of Franklin as an inventor would be better established if
he had not been so resolute in his unwillingness to take out patents upon
his inventions. Besides the various inventions mentioned by us in the text,
he was the father of other valuable mechanical conceptions. The first hint
of the art of engraving upon earthenware appears to have originated with
him. Moved by his constant desire to inculcate moral truths, he suggested
about 1753 to a correspondent the idea of engraving from copper plates on
square chimney tiles "moral prints"; "which," to use his words, "being
about our Chimneys, and constantly in the Eyes of Children when by the
Fireside, might give Parents an Opportunity, in explaining them, to impress
moral Sentiments."
He also appears to have anticipated the Argand burner. A description has
come down to us of a lamp devised by him which, with only three small
wicks, had a lustre equal to six candles. It was fitted with a pipe that
supplied fresh and cool air to its lights. If Franklin did not invent, he
was the first to communicate to his friend, Mr. Viny, the wheel
manufacturer at Tenderden, Kent, the art of flexing timber used in making
wheels for vehicles. But of few things did Franklin take a gloomier view
than the fate of the inventor as his observations in a letter to John
Lining, dated March 18, 1755, demonstrate. "One would not," he said, "of
all faculties or qualities of the mind, wish, for a friend, or a child,
that he should have that of invention. For his attempts to benefit mankind
in that way, however well imagined, if they do not succeed, expose him,
though very unjustly, to general ridicule and contempt; and, if they do
succeed, to envy, robbery, and abuse."