Franklin as a Man of Science
Franklin, as we have said, was primarily a man of action. If we do not
always think of him as deeply involved in what Goethe calls "being's ocean,
action's storm," it is only because he moved from appointed task to
appointed task with such frictionless self-command and ease. But,
throughout his life, his mind was quick to make excursions into the domain
of philosophical speculation and experiment, whenever business cares or
political responsibilities allowed it to do so. Poor Richard would seem to
have little in common with Prometheus, but Prometheus, if Condorcet is to
be believed, as well as Poor Richard, Franklin was; to say nothing of other
transmigrations. That his interest in natural phenomena began at a very
early age, is disclosed by his _Journal of a Voyage from London to
Philadelphia_ in 1726, when he was in his twenty-first year. Throughout the
course of this voyage, his faculties were intently concentrated upon all
the marvels of the sea and its setting. With sedulous minuteness, he
registers the state of the winds each day, and records the impression made
on him by every object with a secret at its heart, to be plucked out by an
inquisitive mind. A lunar rainbow, an eclipse of the sun, which darkened
ten twelfths of his disk, an eclipse of the moon, which spread over six
digits of her surface, dolphins in their bright mail of mixed green, silver
and gold, a shark moving around the ship in a slow, majestic manner, and
attended by an obsequious retinue of pilot fish, schools of harried flying
fish, groups of young crabs, clinging to seaweeds, with indented leaves
about three quarters of an inch long, and small yellow berries filled with
nothing but wind, a white, tropical bird, said never to be seen further
north than latitude 40, and marked by short wings and a single tail
feather, other birds, too near the western continent not to be Americans,
are among the things that the open-eyed and thoughtful youth jotted down in
his Journal in terms that plainly enough indicated not only the eager
curiosity but the exactitude of a future man of science. As almost always,
the child was but the father of the man. Upon each of his subsequent six
voyages across the Atlantic, Franklin exhibited the same, though severer,
and more practised, vigilance in observing everything that the ocean,
including the instruments of commerce afloat on it, have for a penetrating
and suggestive intelligence. How essentially he was a man of science, is
demonstrated by the fact that, whenever he was on the element, where alone
he could hope for exemption from the political demands of his countrymen,
his intellect turned at once with ardor to the study of Nature. Old and
feeble as he was, he wrote no less than three valuable dissertations on his
last voyage across the Atlantic, one on the causes and cure of smoky
chimneys, one on his smoke-consuming stove, and a third, distinguished by
an extraordinary wealth of knowledge and observation, on the construction,
equipment and provisioning of ships, and the winds, currents and
temperature of the sea; which was accompanied by valuable thermometric
tables, based upon observations made by him during three of his
transatlantic voyages. The maritime essay was written with the closest
regard to detail, and contains such a mass of information and luminous
comment as has rarely been condensed into the same space. It makes up some
thirty-four quarto pages of Smyth's edition of Franklin's works, exclusive
of the thermometric notes. The other two essays occupy some forty-nine
pages more. All three are elucidated by numerous explanatory charts and
illustrations, and are marked by the mastery of scientific principles,
which no mere artificer or artisan could have displayed in discussing such
topics; but, at the same time, they could not have been more intensely
practical, as respects minutiae of construction, if Franklin had been a
professional sailor, mason or stove-maker. The maritime observations range
from the Chinese method of dividing the hulls of vessels into separate
compartments, which is now regarded as one of the most efficient devices
for securing the safety of ocean greyhounds, to an inquiry into the reason
why fowls served up at sea are usually too tough to be readily masticated
and the best means of dishing soup on a rolling and pitching vessel.
After his return in his youth from London to Philadelphia, Franklin was for
a long time too much immersed in business and civic projects to give much
attention to natural phenomena. "Why does the flame of a candle tend upward
in a spire?", "whence comes the dew, that stands on the outside of a
tankard that has cold water in it in the summer time?", are among the few
questions of a scientific nature that he appears to have framed for the
discussions of the Junto; and they are elementary enough. But with the
coming of pecuniary ease, the natural bent of his mind soon asserted
itself. While in Boston in 1746, he happened to see some electrical
experiments performed by a Dr. Spence, who had recently arrived from
Scotland. They were clumsily conducted, but crude as they were, they filled
his mind with mixed sensations of surprise and delight; so much so that,
when, shortly after his return to Philadelphia from Boston, the Library
Company found itself the owner of a glass tube, for the production of
electricity by friction, given to it by Peter Collinson, then a Fellow of
the Royal Society of London, with instructions for its use, he eagerly
availed himself of Collinson's generosity to repeat the experiments that he
had witnessed at Boston, and, by continuous practice, became very expert in
making them as well as others. Indeed, his house was soon overrun to such
an extent with eager visitors that he was compelled in self-defence to
relieve it of its congestion by supplying some of his friends with similar
tubes blown at the Philadelphia glass-house. One of these friends was his
ingenious neighbor, Kinnersley, who chanced at the time to be out of
business. Franklin advised him to exhibit the experiments for profit, and
followed up the advice by preparing two lectures for him, in which the
details of the experiments were clearly set forth. Kinnersley himself
employed skilled workmen to make the necessary electrical apparatus for
him, modelled upon the rough agencies designed by Franklin for himself, and
used in his own exhibitions. The lectures, when delivered by him in
Philadelphia, were so well attended that he made a tour of all the chief
towns of the Colonies with a considerable degree of pecuniary success. Some
years later, similar instructions given by Franklin to Domien, a Greek
priest, proved so useful to him on a long tramp that he wrote to his
benefactor that he had lived eight hundred miles upon electricity, and that
it had been meat, drink and clothing to him. When Franklin last heard from
him, he was contemplating a journey from Havana to Vera Cruz, thence
through Mexico to Acapulco, on its western coast, and from Acapulco to
Manila, and from Manila through China, India, Persia and Turkey to his home
in Transylvania; all with electricity as his main _viaticum_.
Franklin's own experiments fortunately ended in something better than
vagabondage, however respectable or profitable. Grateful to Collinson for
his timely gifts, he wrote to him several letters, laying before him the
results of the Philadelphia experiments. Collinson procured for these
letters the privilege of being read before the Royal Society, where they
did not excite enough notice to be printed among its Transactions. Another
letter, one to Kinnersley, in which Franklin propounded the identity of
lightning and electricity, he sent to Dr. Mitchell, an acquaintance of his,
and also a member of the Royal Society, who replied by telling him that it
had been read before the Society, but had been laughed at by the
connoisseurs. Then it was that the happy obstetric suggestion of Dr.
Fothergill that the letters were of too much value to be stifled led
Collinson to gather them together for publication by Cave in the
_Gentleman's Magazine_. They were not published in this magazine, but Cave
did bring them out in pamphlet form with a preface by Dr. Fothergill. The
event showed that he and the general public had more acumen than the sages
of the Royal Society, for the letters, when subsequently published in a
quarto volume, with additions by Franklin, ran through five editions,
without the cost of a penny to Cave for copyright. It was from France,
however, that they first received the full meed of prompt approbation that
they deserved. A copy of them happened to fall into the hands of Buffon,
who prevailed upon D'Alibard to translate them into French. Their
publication in that language provoked an attack upon them by the Abbe
Nollet, Preceptor in Natural Philosophy to the Royal Family, and the author
of a popular theory of Electricity. At first, the Abbe could not believe
that America was capable of producing such letters, and insisted that they
must have been fabricated at Paris for the purpose of discrediting his
system. In fact, he even doubted whether there was such a person as
Franklin, but, afterwards, being convinced upon that point, he published a
volume of letters, mainly addressed to Franklin, in which he defended his
own theory, and denied the accuracy of Franklin's experiments and
conclusions. Le Roy, of the Royal Academy of Sciences, rejoined on behalf
of Franklin, who had decided to let the truth be its own champion, and
easily refuted the Abbe. The papers could not have asked for a better
advertisement than this controversy. They were further translated into the
Italian, German and Latin languages, and Franklin's theory of electricity
was so generally adopted by the learned men of Europe, in preference to
that of the Abbe, that the latter lived, Franklin tells us, to see himself
the last of his sect, except Monsieur B. of Paris, his _eleve_ and
immediate disciple. It is surprising that even the solitary _eleve_ should
have been left clinging to his master; for, in the meantime, the most
momentous experiment, suggested by Franklin in his letters, had been
performed, substantially in the manner outlined by him, with brilliant
success, by D'Alibard, on a hill at Marly-la-Ville, where a pointed rod of
iron, forty feet high, and planted on an electric stand, had been erected
for the purpose of carrying it into execution. When a thundercloud passed
over the rod on May 10, 1752, between 2 and 3 o'clock in the afternoon, the
persons, set by D'Alibard to watch it, had drawn near "and attracted from
it sparks of fire, perceiving the same kind of commotions as in the common
electrical experiments." A week later, the fire and crackling sound,
elicited by M. de Lor from a rod, erected at his house in Paris on a cake
of resin, and electrified by a cloud between 4 and 5 o'clock in the
afternoon, told the same story. He had previously performed what he called
the "Philadelphia experiments" in the presence of Louis XV., who seems to
have been as much delighted with them as if they had been a new mistress.
In a short time, they became so popular that we are told by Franklin that
"all the curious of Paris flocked to see them." One of the results of the
fame acquired by him in France was a letter written by Dr. Wright, an
English physician, then in Paris, to a member of the Royal Society,
apprising the latter of the excitement that the experiments had created in
France, and expressing his astonishment that Franklin's papers had been so
little noticed in England. Quickened by Dr. Wright's words, the Society
reconsidered the letters which had been read before them, and caused an
abstract of them and the other letters on electricity, sent to England by
Franklin, to be printed among its Transactions. Afterwards, when several
members of the Society had themselves drawn down lightning from the clouds,
it elected Franklin a member, and, in view of the fact that the honor had
not been sought by him, voted that he "was not to pay anything"; which
meant that he was to be liable for neither admission fee nor annual dues,
and was even to receive his copy of the Transactions of the Society free of
charge. Nor did it stop here. It also awarded to Franklin, for the year
1753, the Copley gold medal, accompanied by an address, in which Lord
Macclesfield, its President, endeavored to make full amends to him for its
belated recognition of the value of his discoveries.
The suggestion by Franklin, which led to the experiments of D'Alibard and
De Lor, is as matter-of-fact as a cooking recipe.
To determine the question [he said in a letter to Peter
Collinson] whether the clouds that contain lightning
are electrified or not, I would propose an experiment
to be try'd where it may be done conveniently. On the
top of some high tower or steeple, place a kind of
centry box,... big enough to contain a man and an
electrical stand. From the middle of the stand let an
iron rod rise and pass bending out of the door, and
then upright 20 or 30 feet, pointed very sharp at the
end. If the electrical stand be kept clean and dry, a
man standing on it when such clouds are passing low,
might be electrified and afford sparks, the rod drawing
fire to him from a cloud. If any danger to the man
should be apprehended (though I think there would be
none), let him stand on the floor of his box, and now
and then bring near to the rod the loop of a wire that
has one end fastened to the leads, he holding it by a
wax handle; so the sparks, if the rod is electrified,
will strike from the rod to the wire, and not affect
him.
Before the news of the success achieved by D'Alibard and De Lor reached
Franklin, he himself had conducted a similar experiment "though made in a
different and more easy manner." This experiment has become one of the
veriest commonplaces of physical science. It was performed, when a thunder
gust was coming on, in a field near Philadelphia, with such simple
materials as a silk kite, topped off with a foot or more of sharp pointed
wire, and controlled by a twine string, equipped with a key for casting off
the electric sparks, and ending in a silk ribbon to secure the safety of
the hand that held it. The whole construction is set out in a letter
written to Collinson by Franklin shortly after the incident, in which, with
his usual modesty, the latter describes the kite as if he had had nothing
to do with it. Something like the feelings of Sir Isaac Newton, when the
falling apple brought to his ear the real music of the spheres, must have
been those of Franklin, when the loose filaments of twine bristled up
stiffly, as if stirred by some violated instinct of wild freedom, and the
stream of sparks from the key told him that he was right in supposing that
the mysterious and appalling agency, which had for centuries been
associated in the human mind with the resistless wrath of Omnipotence, was
but the same subtle fluid that had so often lit up his electrical apparatus
with its playful corruscations.
The letters to Collinson contained another suggestion almost equally
pregnant. Speaking of the power of pointed conductors to draw off
electricity noiselessly and harmlessly, Franklin asked,
May not the knowledge of this power of points be of use
to mankind, in preserving houses, churches, ships, &c.
from the stroke of lightning, by directing us to fix on
the highest parts of those edifices, upright rods of
iron made sharp as a needle, and gilt to prevent
rusting, and from the foot of those rods a wire down
the outside of the building into the ground, or down
round one of the shrouds of a ship, and down her side
till it reaches the water? Would not these pointed rods
probably draw the electrical fire silently out of a
cloud before it came nigh enough to strike, and thereby
secure us from that most sudden and terrible mischief?
The suggestion was but slowly adopted, not in Europe, indeed, at all, until
the efficacy of the lightning rod in protecting buildings had been
generally recognized in America. In time, however, the device came into use
both in Great Britain and on the Continent; Voltaire being one of the first
persons in Geneva to erect one, and, wherever it was erected, it helped to
confirm the fame of Franklin by its silent effect upon the human
imagination. In recent years, the lightning rod, once in almost universal
use in America, has fallen into neglect, but the explanation of this fact
is to be found not in any just doubts about its utility, when properly
constructed, affixed and grounded, but in the growth of fire insurance, and
the inutility, or danger, of such rods, if carelessly set in place.[51]
The domestication of lightning and the invention of the lightning rod were
the two things to which Franklin was principally indebted for his brilliant
reputation as a philosopher. At this day, the application of electricity to
common uses is so familiar to us that it is hard, without a little
reflection, to realize how well calculated his electrical achievements
were to send a thrill of astonishment and awe through the human mind. Of
all the manifestations of the physical world, lightning with its
inscrutable, swift, and all but irresistible, stroke, followed by the
sublime detonations of thunder, is the one most suggestive of supernatural
influence exerted by an all-powerful deity. The mythological dreams of the
Greeks, the visions of the Old Testament, the simple emotions of the savage
had all paid their homage of dread to the fearful force--like a madman
pitilessly destructive, and yet like a madman diverted from its rage by the
barest trifle--which had clothed Jove with the greater part of his
grandeur, licked up even the water that was in the trench about the altar,
built by Elijah in the name of the Lord, and filled the breast of the
Indian with superstitious terror. Discovery, that laid bare the real nature
and destructive limits of this force, could not fail to excite an
extraordinary degree of attention everywhere. It was the singular fortune
of Franklin, though a practical, sober-minded denizen of the earth, if ever
man was, to have enjoyed in his day a reputation not unlike that of a
divinity of the upper ether.[52] It so happens that the atmosphere was, in
one way or another, the home of all the scientific problems which engaged
his interest most deeply. His philosophical Pegasus, so little akin to the
humble brute bestrid by Poor Richard, was "a beast for Perseus--pure air
and fire"; and especially, it is needless to say, was this true of his
relations to the lightning. When the fact became known throughout the
civilized world that human ingenuity had succeeded in even snaring it,
Franklin was exalted for a time to a seat on Olympus. All the literature
of the period, as well as that of a much later period, bears out the
statement that rarely has any single, peaceful incident ever so fired the
human imagination.[53] For many years, the natural background for a
portrait of Franklin might have been a bank of cloud lit up by the
incessant play of summer lightning. _Eripuit coelo fulmen sceptrumque
tyrannis_, was but the mightiest of the electrical discharges that flattery
poured upon him. Turn where we may to the poetry of the latter half of the
eighteenth century, and of the earlier part of the nineteenth, whether
epigram or otherwise, we are likely to come upon some imprint left upon the
thought of those periods by the subjugation of lightning.
The interest of Franklin in electrical science was but another sequel of
the world-wide avidity with which learned men had recently turned to the
study of that subject. One of them, Grey, had pursued a series of
experiments for the purpose of determining the relative conductivity of
various substances, another, Du Fay, had erroneously classified electricity
as resinous and vitreous, and the perfected Leyden Jar particularly had
given a new momentum to the progress of electrical investigation. Into this
movement, after witnessing Dr. Spence's awkward experiments at Boston,
Franklin threw himself with the utmost enthusiasm, and his discovery of
the identity of lightning and electricity and his lightning-rod conception
were but the chief fruits of this enthusiasm. Between the _Autobiography_
and his letters, we are at no loss to follow closely the steps by which he
reached all the results which have given him such a high position as an
electrical investigator. "I purchased all Dr. Spence's apparatus ..." he
tells us in the _Autobiography_, "and I proceeded in my electrical
experiments with great alacrity." How keen this alacrity became, after he
had been rubbing for a time the glass tube, sent over to Philadelphia by
Collinson, may be seen in what he wrote to Collinson himself on March 28,
1747:
For my own part, I never was before engaged in any
study that so totally engrossed my attention and my
time as this has lately done; for what with making
experiments when I can be alone, and repeating them to
my Friends and Acquaintance, who, from the novelty of
the thing, come continually in crouds to see them, I
have, during some months past, had little leisure for
anything else.
The result of this experimentation was the various letters to Collinson and
others that constitute Franklin's highest claim to distinction as a man of
science. By following them in their chronological order, the reader can
trace with little difficulty the genesis of each of his more valuable
conclusions touching electricity. They are distinguished by remarkable
simplicity and force of reasoning and by a clearness of statement as
transparent as crystal. Moreover, they are even enlivened at times by
gleams of fancy or humor. In a word they indisputably merit the judgment
that Sir Humphry Davy, no mean judge of style as well as scientific truth,
passes upon them:
The style and manner of his publication on electricity
are almost as worthy of admiration as the doctrine it
contains. He has endeavoured to remove all mystery and
obscurity from the subject. He has written equally for
the uninitiated and the philosopher; and he has
rendered his details amusing as well as perspicuous,
elegant as well as simple. Science appears in his
language in a dress wonderfully decorous, the best
adapted to display her native loveliness. He has in no
instance exhibited that false dignity, by which
philosophy is kept aloof from common applications; and
he has sought rather to make her a useful inmate and
servant in the common habitations of man, than to
preserve her merely as an object of admiration in
temples and palaces.
While recalling these words, it is not amiss to recall, too, what Lord
Brougham had to say about the agencies with which Franklin conducted his
experiments.
He could make an experiment [said Brougham] with less
apparatus and conduct his experimental inquiry to a
discovery with more ordinary materials than any other
philosopher we ever saw. With an old key, a silk
thread, some sealing wax and a sheet of paper he
discovered the identity of lightning and electricity.
The truth of these observations is strikingly instanced in a story told of
Franklin in Pettigrew's _Life of Lettsom_. When Henry Smeathman was
insisting that the flight of birds is on inclined planes, and that they
could not fly at all, but would simply float with the wind, if they were
not heavier than the air, Franklin launched half a sheet of paper obliquely
into the air, observing, as he watched its course, that that was an evident
proof of the propriety of Smeathman's doctrines.
In a letter to Collinson, dated July 11, 1747, Franklin communicated to him
the earliest results of his experimental use of the glass tube that
Collinson had sent over to Philadelphia. The first phenomenon, which fixed
his attention, was the wonderful effect of pointed bodies in drawing off
the electrical fire. This was the lightning rod in its protoplasmal stage.
The manner in which he described the experiment, by which this particular
truth was demonstrated, is a good specimen of his remarkable faculty for
simple and clear statement:
Place an iron shot of three or four inches diameter on
the mouth of a clean dry glass bottle. By a fine silken
thread from the ceiling, right over the mouth of the
bottle, suspend a small cork ball, about the bigness of
a marble; the thread of such a length, as that the cork
ball may rest against the side of the shot. Electrify
the shot, and the ball will be repelled to the distance
of four or five inches, more or less, according to the
quantity of Electricity. When in this state, if you
present to the shot the point of a long slender sharp
bodkin, at six or eight inches distance, the repellency
is instantly destroy'd, and the cork flies to the shot.
A blunt body must be brought within an inch, and draw a
spark, to produce the same effect. To prove that the
electrical fire is _drawn off_ by the point, if you
take the blade of the bodkin out of the wooden handle,
and fix it in a stick of sealing wax, and then present
it at the distance aforesaid, or if you bring it very
near, no such effect follows; but sliding one finger
along the wax till you touch the blade, and the ball
flies to the shot immediately. If you present the point
in the dark, you will see, sometimes at a foot
distance, and more, a light gather upon it, like that
of a firefly, or glowworm; the less sharp the point,
the nearer you must bring it to observe the light; and,
at whatever distance you see the light, you may draw
off the electrical fire, and destroy the repellency. If
a cork ball so suspended be repelled by the tube, and a
point be presented quick to it, tho' at a considerable
distance, 'tis surprizing to see how suddenly it flies
back to the tube. Points of wood will do near as well
as those of iron, provided the wood is not dry; but
perfectly dry wood will no more conduct electricity
than sealing-wax.
The repellency between the ball and the shot was likewise destroyed,
Franklin stated, 1, by sifting fine sand on it; this did it gradually, 2,
by breathing on it, 3, by making a smoke about it from burning wood, and 4,
by candlelight, even though the candle was at a foot distance; these did
it suddenly.
* * * * *
The same result was also produced, he found, by the light of a bright coal
from a wood fire, or the light of red-hot iron; but not at so great a
distance. Such was not the effect, however, he said, of smoke from dry
resin dropped on hot iron. It was merely attracted by both shot and cork
ball, forming proportionable atmospheres round them, making them look
beautifully, somewhat like some of the figures in Burnet's or Whiston's
_Theory of the Earth_.
Franklin also noted the fact that, unlike fire-light, sunlight, when thrown
on both cork and shot, did not impair the repellency between them in the
least.
In the same letter, guided by the belief that he had formed that
electricity is not created by friction but, except when accumulated or
depleted by special causes, is equally diffused through material substances
generally, he also reached the conclusion that electrical discharges are
due to circuits set up by substances that offer little resistance to the
transit of the electrical current between bodies charged with more than the
ordinary quantity of electrical energy and bodies not in that condition. In
other words, electricity is always alert to restore its equilibrium when
lost, and, if accumulated beyond its normal measure in one body, seeks with
violent eagerness, as soon as a favorable medium of transmission is
presented to it, to pass on its surplus of electrical energy to another
body less amply supplied.
These conceptions, too, which lie at the very foundations of modern
electrical science, are illustrated by Franklin with extraordinary
simplicity and clearness as follows:
1. A person standing on wax, and rubbing the tube, and
another person on wax drawing the fire, they will both
of them, (provided they do not stand so as to touch one
another) appear to be electrised, to a person standing
on the floor; that is, he will perceive a spark on
approaching each of them with his knuckle.
2. But, if the persons on wax touch one another during
the exciting of the tube, neither of them will appear
to be electrised.
3. If they touch one another after exciting the tube,
and drawing the fire as aforesaid, there will be a
stronger spark between them, than was between either of
them and the person on the floor.
4. After such strong spark, neither of them discover
any electricity.
These appearances we attempt to account for thus: We
suppose, as aforesaid, that electrical fire is a common
element, of which every one of the three persons above
mentioned has his equal share, before any operation is
begun with the tube. A, who stands on wax and rubs the
tube, collects the electrical fire from himself into
the glass; and his communication with the common stock
being cut off by the wax, his body is not again
immediately supply'd. B, (who stands on wax likewise)
passing his knuckle along near the tube, receives the
fire which was collected by the glass from A; and his
communication with the common stock being likewise cut
off, he retains the additional quantity received. To C,
standing on the floor, both appear to be electrised:
for he having only the middle quantity of electrical
fire, receives a spark upon approaching B, who has an
over quantity; but gives one to A, who has an under
quantity. If A and B approach to touch each other, the
spark is stronger, because the difference between them
is greater: After such touch there is no spark between
either of them and C, because the electrical fire in
all is reduced to the original equality. If they touch
while electrising, the equality is never destroy'd, the
fire only circulating. Hence have arisen some new terms
among us: We say, B, (and bodies like circumstanced) is
electrised _positively_; A, _negatively_. Or rather, B
is electrised _plus_; A, _minus_. And we daily in our
experiments electrise bodies _plus_ or _minus_, as we
think proper. To electrise _plus_ or _minus_, no more
needs to be known than this, that the parts of the tube
or sphere that are rubbed, do, in the instant of the
friction, attract the electrical fire, and therefore
take it from the thing rubbing: The same parts
immediately, as the friction upon them ceases, are
disposed to give the fire they have received, to
anybody that has less. Thus you may circulate it, as
Mr. _Watson_ has shown; you may also accumulate or
subtract it upon, or from anybody, as you connect that
body with the rubber or with the receiver, the
communication with the common stock being cut off.
The same letter recounts some of the tricks that Franklin and his
fellow-experimenters were in the habit of making their new plaything
perform. They fired spirits, lit candles just blown out, mimicked
lightning, produced sparks with the touch of the finger, on the human hand
or face, and gave electrical kisses. Other feats consisted in animating an
artificial spider in such a way as to keep him oscillating in a very
lifelike and entertaining manner between two wires, and lighting up the
gilding on the covers of a book with a brilliant flash. This letter also
shows that the provincial philosophers had already made improvements in the
usual electrical methods. They had found that it was better to fill the
phial with granulated lead than with water because of the superior facility
with which the former could be warmed, and kept warm and dry in a damp
place. They rubbed their tubes with buckskin, and, by observing certain
precautions, such as never sullying the tubes by handling them, and keeping
them in tight, close-fitting cases of pasteboard, lined with flannel,
increased their efficiency. Their spheres for charging phials with
electricity were mounted on iron axes with a small handle on one end, with
which they could be set revolving like a common grindstone. It was in this
same letter that Franklin with his usual generosity was careful to state
that the power of pointed bodies to throw off as well as draw off the
electrical fire was a discovery of his friend Hopkinson, and that the
revolving sphere used by them was the invention of his friend Syng. About a
month later, Franklin wrote to Collinson that, in the course of further
experiments, he had observed several phenomena which made him distrust some
of his former conclusions. "If there is no other use discover'd of
Electricity," he said, "this however is something considerable, that it may
_help to make a vain man humble_."
Another letter from Franklin to Collinson, written about two weeks later,
communicated to him some valuable observations upon "M. Muschenbroeck's
wonderful bottle"--the Leyden Jar. This bottle was a mere ordinary bottle,
with a common cork in its neck, into which a common wire had been inserted.
He wrote that, at the same time that the wire and the top of the bottle
were electrised positively or plus, the bottom of the bottle was electrised
negatively or minus, in exact proportion; the consequence was that,
whatever quantity of electrical fire was thrown in at the top, an equal
quantity went out at the bottom until, if the process was kept up long
enough, the point was reached in the operation, when no more could be
thrown into the upper part of the bottle, because no more could be drawn
out of the lower part. If the attempt was made to throw more in, the fire
was spewed back through the wire, or flew out in loud cracks through the
sides of the bottle.
He also noted that an equilibrium could not be restored in the bottle by
inward communication or contact of the parts, but only by a communication,
formed without the bottle between its top and bottom.
He also noted that no electrical fire could be thrown into the top of the
bottle, when none could get out at its bottom, either because the bottom
was too thick, or because it stood on some non-conducting material, and
likewise that, when the bottle was electrified, but little of the
electrical fire could be drawn from the top by touching the wire, unless
an equal quantity could at the same time get in at the bottom.
So wonderfully [he adds] are these two states of
electricity, the _plus_ and _minus_, combined and
balanced in this miraculous bottle! situated and
related to each in a manner that I can by no means
comprehend! If it were possible that a bottle should in
one part contain a quantity of air strongly comprest,
and in another part a perfect vacuum, we know the
equilibrium would be instantly restored _within_. But
here we have a bottle containing at the same time a
_plenum_ of electrical fire, and a _vacuum_ of the same
fire; and yet the equilibrium cannot be restored
between them but by a communication without! though the
_plenum_ presses violently to expand, and the hungry
vacuum seems to attract as violently in order to be
filled.
The letter concludes with an elaborate statement of the experiments by
which the correctness of its conclusions could be established.
Franklin's next discovery communicated to Collinson in a letter dated the
succeeding year was that, when the bottle was electrified, the electric
fluid resided in the glass itself of the bottle. The manner in which he
proved this fact is a good example of his inductive thoroughness.
Purposing [he said] to analyze the electrified bottle,
in order to find wherein its strength lay, we placed it
on glass, and drew out the cork and wire, which for
that purpose had been loosely put in. Then taking the
bottle in one hand, and bringing a finger of the other
near its mouth, a strong spark came from the water, and
the shock was as violent as if the wire had remained in
it, which shewed that the force did not lie in the
wire. Then, to find if it resided in the water, being
crouded into and condensed in it, as confin'd by the
glass, which had been our former opinion, we
electrified the bottle again, and, placing it on glass,
drew out the wire and cork as before; then, taking up
the bottle, we decanted all its water into an empty
bottle, which likewise stood on glass; and taking up
that other bottle, we expected, if the force resided in
the water, to find a shock from it; but there was
none. We judged then, that it must either be lost in
decanting, or remain in the first bottle. The latter we
found to be true; for that bottle on trial gave the
shock, though filled up as it stood with fresh
unelectrified water from a teapot.
By a similar course of experimentation with sash glass and lead plates, he
also demonstrated that the form of the glass in the bottle was immaterial,
that the power resided in the glass as glass, and that the non-electrics in
contact served only like the armature of a loadstone to unite the force of
the several parts, and to bring them at once to any point desired; it being
the property of a non-electric that the whole body instantly receives or
gives what electric fire is given to, or taken from, anyone of its parts.
These experiments suggested the idea of intensifying the application of
electrical forces by grouping numerous electrical centres.
We made [he said] what we called an _electrical
battery_, consisting of eleven panes of large
sash-glass, arm'd with thin leaden plates, pasted on
each side, placed vertically, and supported at two
inches distance on silk cords, with thick hooks of
leaden wire, one from each side, standing upright,
distant from each other, and convenient communications
of wire and chain, from the giving side of one pane, to
the receiving side of the other; that so the whole
might be charged together, and with the same labour as
one single pane; and another contrivance to bring the
giving sides, after charging, in contact with one long
wire, and the receivers with another, which two long
wires would give the force of all the plates of glass
at once through the body of any animal forming the
circle with them. The plates may also be discharged
separately, or any number together that is required.
When the idea of the electrical battery was formed by him, Franklin was not
aware that Smeaton and Bains had previously assembled panes of glass for
the purpose of giving an electrical shock.
At the time that this letter was written, Franklin had added to his
electrical exploits that of electrifying a mezzotint of the King in such a
manner that, if anyone attempted to take the crown off his head, he would
receive a "terrible blow."
If the picture were highly charged [he said], the
consequence might perhaps be as fatal as that of high
treason.
The operator [he continues], who holds the picture by
the upper end, where the inside of the frame is not
gilt, to prevent its falling, feels nothing of the
shock, and may touch the face of the picture without
danger, which he pretends is a test of his loyalty. If
a ring of persons take the shock among them, the
experiment is called _The Conspirators_.
Another far more significant exploit was the application of electrical
energy in such a way as to set an electrical Jack revolving with such force
and swiftness as to carry a spitted fowl around before a fire with a motion
fit for roasting.
This wheel was driven by an electrical battery, but Franklin also devised
what he called a self-moving wheel that was, by a different electrical
method, revolved with so much force and rapidity that he thought that it
might be used for the ringing of chimes and the movement of light-made
orreries. And after observing that a thin glass bubble, about an inch in
diameter, weighing only six grains, being half filled with water, partly
gilt on the outside, and furnished with a wire hook, gave, when
electrified, as great a shock as a man can well bear, Franklin exclaims,
"How great must be the quantity (of electrical fire) in this small portion
of glass! It seems as if it were of its very substance and essence. Perhaps
if that due quantity of electrical fire so obstinately retained by glass,
could be separated from it, it would no longer be glass; it might lose its
transparency, or its brittleness, or its elasticity."
This letter also reaches the conclusion that bodies, having less than the
common quantity of electricity, repel each other, as well as those that
have none.
It concludes with a lively paragraph:
Chagrined a little that we have been hitherto able to
produce nothing in this way of use to mankind; and the
hot weather coming on, when electrical experiments are
not so agreeable, it is proposed to put an end to them
for this season, somewhat humorously, in a party of
pleasure on the banks of _Skuylkil_. Spirits, at the
same time, are to be fired by a spark sent from side to
side through the river, without any other conductor
than the water; an experiment which we some time since
performed, to the amazement of many. A turkey is to be
killed for our dinner by the _electrical shock_, and
roasted by the _electrical jack_, before a fire kindled
by the _electrified bottle_; when the healths of all
the famous electricians in _England_, _Holland_,
_France_ and _Germany_ are to be drank in _electrified
bumpers_, under the discharge of guns from the
_electrical_ battery.
An electrified bumper, a note to the letter explained, was a small thin
glass tumbler, nearly filled with wine, and charged, which, when brought to
the lips of a person, gave him a shock, if he was close-shaved, and did not
breathe on the liquor. Another note states that the biggest animal that the
experimenters had yet killed was a hen.
A later letter to Collinson on the phenomena of thunder-gusts takes
Franklin away from the Leyden Jar of the laboratory to the stupendous
batteries of the outer universe--from the point of a bodkin to the lofty
natural or artificial objects, upon which lightning descends from the
illimitable sky. "As electrified clouds pass over a country," he remarks,
"high hills and high trees, lofty towers, spires, masts of ships, chimneys,
&c., as so many prominencies and points, draw the electrical fire, and the
whole cloud discharges there." From this observation to the lightning rod
was but a short step.
Another letter to Collinson in the succeeding year brings us to the
lightning rod in principle if not in name. Speaking of what a sea captain
had said of luminous objects, which had settled on the spintles at the
topmast heads of his ship before an electrical shock, and burned like very
large torches, he says:
According to my opinion, the electrical fire was then
drawing off, as by points, from the cloud; the
largeness of the flame betokening the great quantity of
electricity in the cloud: and had there been a good
wire communication from the spintle heads to the sea,
that could have conducted more freely than tarred
ropes, or masts of turpentine wood, I imagine there
would either have been no stroke; or, if a stroke, the
wire would have conducted it all into the sea without
damage to the ship.
In the same letter, there is an adumbration of his grandest experiment,
when he speaks of the flash from two of his jars as "our mimic lightning."
This letter also shows that with electricity Franklin had frequently
imparted polarity to needles and reversed it at pleasure. Wilson, at
London, he said, had failed to produce these results because he had tried
it on too large masses and with too small force. The letter also evidences
the fact that he had employed the electric spark for the practical purpose
of firing gunpowder.
Another letter to Collinson dated July 29, 1750, is accompanied by an
additional paper on the properties and effects of the Electrical Matter. It
acknowledges the debt that Franklin owed to Collinson for the glass tube
and the instructions which attended it, and to the Proprietary for the
generous present of a complete electrical apparatus which "that bountiful
benefactor to our library," as he calls him, had made to it. The telegraph,
the Marconi tower, the telephone, the electric bulb, the electric
automobile and the trolley car rise up before us when we read this
observation in the paper that accompanied the letter: "The beneficial uses
of this electric fluid in the creation, we are not yet well acquainted
with, though doubtless such there are, and those very considerable." The
paper is the most important that Franklin ever wrote on electricity;
containing as it does the two suggestions which, when carried into
execution, made his name famous throughout the world, that is to say, his
suggestion, already quoted by us at length, that houses, churches and ships
might be protected by upright rods of iron, and his suggestion, already
quoted by us, too, as to how the identity of lightning and electricity
could be established. The point of the bodkin and the electrified shot and
ball, and the mimic brightness, agility and fury of the lurking fire in the
wonderful bottle had led, step by step, to two of the most splendid
conceptions in the early history of electrical science.[54]
With the discovery that electricity and lightning were the same thing, the
real achievements of Franklin in the province of electricity came to an
end. But he still continued his electrical experiments with undiminished
ardor. We find him on one occasion prostrating with a single shock six
persons who were so obliging as to lend themselves to the pursuit of
scientific truth. Twice he was the victim of his own inadvertence. Speaking
of one of these occasions, in a letter to a friend in Boston, he said:
The flash was very great, and the crack as loud as a
pistol; yet, my senses being instantly gone, I neither
saw the one nor heard the other; nor did I feel the
stroke on my hand, though I afterwards found it raised
a round swelling where the fire entered, as big as half
a pistol-bullet; by which you may judge of the
quickness of the electrical fire, which by this
instance seems to be greater than that of sound, light,
or animal sensation.... I then felt what I know not how
well to describe; a universal blow throughout my whole
body from head to foot, which seemed within as well as
without; after which the first thing I took notice of
was a violent quick shaking of my body, which gradually
remitting, my sense as gradually returned, and then I
thought the bottles must be discharged, but could not
conceive how, till at last I perceived the chain in my
hand, and recollected what I had been about to do. That
part of my hand and fingers, which held the chain, was
left white, as though the blood had been driven out,
and remained so eight or ten minutes after, feeling
like dead flesh; and I had a numbness in my arms and
the back of my neck, which continued till the next
morning, but wore off. Nothing remains now of this
shock, but a soreness in my breast-bone, which feels as
if it had been bruised. I did not fall, but suppose I
should have been knocked down, if I had received the
stroke in my head. The whole was over in less than a
minute.
On the second occasion, while making ready to give a healing shock to a
paralytic, he received a charge through his own head. He did not see the
flash, hear the report or feel the stroke.
When my Senses returned [he told Jan Ingenhousz], I
found myself on the Floor. I got up, not knowing how
that had happened. I then again attempted to discharge
the Jars; but one of the Company told me they were
already discharg'd, which I could not at first
believe, but on Trial found it true. They told me they
had not felt it, but they saw I was knock'd down by it,
which had greatly surprised them. On recollecting
myself, and examining my Situation, I found the Case
clear. A small swelling rose on the Top of my Head,
which continued sore for some Days; but I do not
remember any other Effect good or bad.
One of Franklin's contemporaries, Professor Richmann, of St. Petersburg,
did not fare so well; for a stroke of the lightning that he had allured
from the clouds brought his life to an end. Priestley, however, seems to
have regarded such a death as a form of euthanasia. At any rate, in
speaking of this martyr of science in his _History of Electricity_ he terms
him "the justly envied Richmann."
After Franklin learned how to impound lightning, his intercourse with
electricity was more familiar than ever.
In September, 1752 [he wrote to Collinson], I erected
an iron rod to draw the lightning down into my house,
in order to make some experiments on it, with two bells
to give notice when the rod should be electrify'd: a
contrivance obvious to every electrician.
I found the bells rang sometimes when there was no
lightning or thunder, but only a dark cloud over the
rod; that sometimes, after a flash of lightning, they
would suddenly stop; and, at other times, when they had
not rang before, they would, after a flash, suddenly
begin to ring; that the electricity was sometimes very
faint, so that, when a small spark was obtain'd,
another could not be got for some time after; at other
times the sparks would follow extremely quick, and once
I had a continual stream from bell to bell, the size of
a crow quill: Even during the same gust there were
considerable variations.
In the winter following I conceived an experiment, to
try whether the clouds were electrify'd _positively_ or
_negatively_.
The result of these experiments, conducted with Franklin's usual
painstaking completeness, was the conclusion on his part that
thunder-clouds are, as a rule, in a negatively electrical state, and that,
therefore, generally speaking, they do not discharge electricity upon the
earth, but receive it from the earth. For the most part, he said, "_tis the
earth that strikes into the clouds, and not the clouds that strike into the
earth_."
The thoroughness with which he addressed himself to the study of
electricity was very marked. His investigation was as searching and minute
as that of an anatomist engaged in the dissection of nervous tissue. Under
his hands, the bare Leyden Jar became a teeming storehouse of instruction
and amusement. He collected electricity from common objects by friction, he
brought it down from the sky, he sought its properties in amber, in the
tourmaline stone, in the body of the torpedo; he thought that he discerned
it in the radiance of the Aurora Borealis. He put it through all its
vagaries, juggled with it, teased it, cowed it until it confessed its
kinship with the tempestuous heavens. He tested its destructive effects
upon hens and turkeys, its therapeutic value to paralytic patients, its
efficacy as a corrective of tough meat. He even, it is said, charged the
railing under his windows with it to repel loafers standing about his front
door. And, in his relations to electricity, as to everything else, his
purposes were always those of practical utility. In one of his papers, he
admits that he cannot tell why points possess the power of drawing off the
electrical fire;
nor is it of much importance to us [he adds] to know
the manner in which nature executes her laws. 'Tis
enough if we know the laws themselves. 'Tis of real use
to know that china left in the air unsupported will
fall and break; but _how_ it comes to fall, and _why_
it breaks, are matters of speculation. 'Tis a pleasure
indeed to know them, but we can preserve our china
without it.
He anticipated, or, in some instances, all but anticipated, several of the
more important discoveries of modern electrical science. He knew that,
when a number of Leyden jars are connected up under certain conditions, the
extent, to which each jar can be charged from a given source, varies
inversely as the number of jars. For a time, he was puzzled by the fact
that the light of a candle, or of a fire-coal, or of red-hot iron, would
destroy the repellency between his electrified ball and shot, but that the
light of the sun would not. But it was not long before he hit upon this
ingenious explanation:
This different Effect probably did not arise from any
difference in the light, but rather from the particles
separated from the candle, being first attracted and
then repelled, carrying off the electric matter with
them; and from the rarefying the air, between the
glowing coal or red-hot iron, and the electrised shot,
through which rarefied air the electric fluid could
more readily pass.
Referring to what Franklin had to say about the action of sunlight in this
connection, Arthur Schuster, in his _Some Remarkable Passages in the
Writings of Benjamin Franklin_, observes: "Had Franklin used a clean piece
of zinc instead of iron shot he might have anticipated Hertz's discovery of
the action of strong light on the discharge of gases."
In the course of one of his experiments with an electrified can, Franklin
reached the conclusion that a cork, which he had lowered into the can, was
not attracted to its internal surface, as it would have been to its
external, because the mutual repulsion of the two inner opposite sides of
the can might prevent the accumulation of an electrical atmosphere upon
them. From the same experiment, the genius of Henry Cavendish deduced his
law that electrical repulsion varies inversely as the square of the
distance between the charges.
Instead of declining, it can truly be said that the reputation of Franklin
as an electrical investigator and writer has increased with the progress
of electrical science. "We shall, I am sure," remarks Professor J. J.
Thomson in his _Electricity and Matter_, "be struck by the similarity
between some of the views which we are led to take by the results of the
most recent researches, with those enunciated by Franklin in the very
infancy of the subject." Nor should we omit a tribute of Dr. William
Garnett, in his _Heroes of Science_, in regard to the statements in
Franklin's first letters to Collinson. "They are," he says, "perfectly
consistent with the views held by Cavendish and by Clerk Maxwell, and,
though the phraseology is not that of modern text-books, the statements
themselves can hardly be improved upon to-day."
If Franklin achieved a higher degree of success in the electrical than in
any other scientific field, it was partly, at any rate, because he never
again had the opportunity to give such continuous attention to scientific
pursuits. To him this was at times a source of very great disappointment.
In one of his letters to Beccaria, dated Sept. 21, 1768, he tells the
latter that, preoccupied as he was, he had constantly cherished the hope of
returning home, where he could find leisure to resume the philosophical
studies that he had shamefully put off from time to time. In a letter, some
eleven years later, from Paris, to the same correspondent, he said that he
was then prevented by similar distractions from pursuing those studies in
which he always found the highest satisfaction, and that he was grown so
old as hardly to hope for a return of the leisure and tranquillity, so
necessary for philosophical disquisitions. To Sir Joseph Banks he was
inspired some years later, by recent astronomical discoveries, made under
the patronage of the Royal Society, to write: "I begin to be almost sorry I
was born so soon, since I cannot have the happiness of knowing what will be
known 100 years hence," Indeed, to him, leisure, whether only the seclusion
of a thirty-day voyage across the Atlantic, or the final cessation of
public life, was but another term for recurrence to his scientific
predilections. When he received his leave from Congress to return home from
Paris, he wrote joyously to Ingenhousz: "I shall now be free of Politicks
for the Rest of my Life. Welcome again my dear Philosophical Amusements."
There was, to use his own expression, still too much flesh on his bones for
his countrymen to allow him any time except for political experiments; but,
for proof of the eager interest that he felt in science, and of the
prominent position, that he occupied in the scientific world of America,
until the last, we need go no further than the fact that, when he died, the
meetings of the American Philosophical Society had, for some time, been
held at his home in Philadelphia.
How far Franklin might have added to his reputation as a man of science, if
he had not become engrossed by political duties and cares, is mere matter
of surmise. But there can be no doubt that he was eminently fitted in many
respects for scientific inquiry. The scientific temperament he possessed in
the very highest degree. He loved the truth too much to allow the workings
of human weakness in himself or others to deface its fair features. In
reporting to Collinson the electrical achievements, which crowned him with
such just renown, he almost invariably spoke of them as if they were the
joint achievements of a group of collaborators, of whom he was but one. The
generous alacrity, with which he credits to his friends Hopkinson,
Kinnersley, or Syng exclusively special discoveries or inventions, made by
them, shows conclusively enough how little this was true. There is no
reason to believe that his letters to Collinson on electricity would ever
have been published but for the unsolicited initiative of Dr. Fothergill
and Collinson; or that they would ever have been translated into French but
for the spontaneous persuasion that Buffon brought to bear upon D'Alibard.
In a letter to Collinson, after expressing distrust of an hypothesis,
advanced by him in former letters to the same correspondent, he declares
that he is ashamed to have expressed himself in so positive a manner.
Indeed, he said, he must request Collinson not to expose those letters, or,
if he communicated them to any of his friends, at least to conceal the name
of the author. His attitude towards his scientific triumphs was, when not
that of entire self-effacement, always that of unaffected humility.
I am indebted for your preceding letter [he wrote in
his forty-seventh year to John Perkins] but business
sometimes obliges one to postpone philosophical
amusements. Whatever I have wrote of that kind, are
really, as they are entitled, but _Conjectures_ and
_Suppositions_; which ought always to give place, when
careful observation militates against them. I own I
have too strong a penchant to the building of
hypotheses; they indulge my natural indolence: I wish I
had more of your patience and accuracy in making
observations, on which, alone, true philosophy can be
founded.
Equally candid and noble are other observations in a subsequent letter to
the same correspondent. Referring to certain objections, made by Perkins to
his theory of water spouts, he observed:
Nothing certainly can be more improving to a Searcher
into Nature, than Objections judiciously made to his
Opinions, taken up perhaps too hastily: For such
Objections oblige him to re-study the Point, consider
every Circumstance carefully, compare Facts, make
Experiments, weigh Arguments, and be slow in drawing
Conclusions. And hence a sure Advantage results; for he
either confirms a Truth, before too lightly supported;
or discovers an Error, and receives Instruction from
the Objector.
In this View I consider the Objections and Remarks you
sent me, and thank you for them sincerely.
When he found that he was in error, it cost him no struggle to recant. For
a while he believed the sea to be the grand source of lightning, and built
up an imposing fabric of conclusions upon the belief; but he did not
hesitate afterwards to admit that he had embraced this opinion too hastily.
The same thing is true of the opinion that he held for a time, that the
progress of a ship westward, across the Atlantic, is retarded by the
diurnal motion of the earth. He supposed that the melting brought about by
the action of lightning was a cold fusion until holes burnt in a floor by
portions of a molten bell wire convinced him that this was not so.
I was too easily led into that error [he said] by
accounts given even in philosophical books, and from
remote ages downwards, of melting money in purses,
swords in scabbards, etc. without burning the
inflammable matters that were so near those melted
metals. But men are, in general, such careless
observers, that a philosopher can not be too much on
his guard in crediting their relations of things
extraordinary, and should never build an hypothesis on
anything but clear facts and experiments, or it will be
in danger of soon falling, as this does, like a house
of cards.
In one of his letters to Collinson, he declared that, even though future
discoveries should prove that certain conjectures of his were not wholly
right, yet they ought in the meantime to be of some use by stirring up the
curious to make more experiments and occasion more exact disquisitions.
Following out the same thought in another letter to Collinson he concluded:
"You are at liberty to communicate this paper to whom you please; it being
of more importance that knowledge should increase, than that your friend
should be thought an accurate philosopher." In a letter to John Lining, in
which he described the experiment from which Cavendish deduced the law of
which we have spoken, he observed:
I find a frank acknowledgement of one's ignorance is
not only the easiest way to get rid of a dificulty, but
the likeliest way to obtain information, and therefore
I practise it: I think it an honest policy. Those who
affect to be thought to know everything, and so
undertake to explain everything often remain long
ignorant of many things that others could and would
instruct them in, if they appeared less conceited.
The fact is that Franklin had such a keen sense of the dignity and
invincibility of truth that he could not be induced to enter into any
personal controversy about it. His feelings with regard to such
controversies are pointedly expressed in the _Autobiography_ in connection
with the attack made by the Abbe Nollet upon his electrical experiments.
I once purpos'd [he said] answering the abbe, and
actually began the answer; but, on consideration that
my writings contain'd a description of experiments
which anyone might repeat and verify, and if not to be
verifi'd, could not be defended; or of observations
offer'd as conjectures, and not delivered dogmatically,
therefore not laying me under any obligation to defend
them; and reflecting that a dispute between two
persons, writing in different languages, might be
lengthened greatly by mistranslations, and thence
misconceptions of one another's meaning, much of one of
the abbe's letters being founded on an error in the
translation, I concluded to let my papers shift for
themselves, believing it was better to spend what time
I could spare from public business in making new
experiments, than in disputing about those already
made.
But in this instance, too, after all, he acted upon the principle, stated
in one of his letters to Cadwallader Colden, that he who removes a
prejudice, or an error from our minds contributes to their beauty, as he
would do to that of our faces who should clear them of a wart or a wen. He
went through his experiments again, and satisfied himself that the Abbe had
not shaken his positions. At one time, when he was hesitating as to whether
he should reply to him, he heard that D'Alibard was preparing to do so.
"Perhaps," he wrote to his friend, James Bowdoin, "it may then appear
unnecessary for me to do anything farther in it. And will not one's vanity
be more gratified in seeing one's adversary confuted by a disciple, than
even by one's self?" When Wilson published a pamphlet, contending that
lightning rods should be blunt rather than pointed, he simply observed, "I
have not answered it, being averse to Disputes."
Not only his temperament but his general mental attitude was instinctively
scientific. As we have seen, while Whitefield's other auditors were
standing mute and spellbound, he was carefully computing the distance that
the words of the orator would carry. As we have also seen, when his
soldiers were cutting down the giant pines at Gnadenhutten, he had his
watch out, deep in his observation of the time that it took them to fell a
tree. When his friend, Small, complained of deafness, he wrote to him that
he had found by an experiment at midnight that, by putting his thumb and
fingers behind his ear, and pressing it out and enlarging it as it were
with the hollow of his hand, he could hear the tick of a watch at the
distance of forty-five feet which was barely audible at a distance of
twenty feet without these aids. Even in his relations to the simplest
concerns of life, he had always the eye of a man of science to weight,
measure, dimension and distance. If anyone wishes to see how easily he
reduced everything to its scientific principles, let him read Franklin's
letter to Oliver Neave, who thought that it was too late in life for him to
learn to swim. With the confidence bred by a proper sense of the specific
gravity of the human body as compared with that of water, Franklin said,
there was no reason why a human being should not swim at the first trial.
If Neave would only wade out into a body of water, until it came up to his
breast and by a cast of his hand sink an egg to the bottom, between him and
the shore, where it would be visible, but could not be reached except by
diving, and then endeavor to recover it, he would be surprised to find what
a buoyant thing water was.
Franklin also had all the inquisitiveness of a born philosopher. The winds,
the birds, the fish, the celestial phenomena brought to his attention on
his first voyage from England, the sluggish movement of his ship on his
voyage to England in 1757, the temperature and movement of the Gulf Stream,
the social and religious characteristics of the Moravians, Indian traits
and habits, the still flies in their bath of Madeira wine--all excited his
insatiable curiosity, and started him off on interesting trains of
observation or reflection.
He was in the 78th year of his age, when, in the sight of fifty thousand
people, one of the balloons recently invented by the Montgolfiers, and
inflated with gas, produced by pouring oil of vitriol on iron filings,
ascended from the Champs de Mars, shining brightly in the sun during the
first stages of its ascent, then dwindling until it appeared scarcely
larger than an orange, and then melting away in the clouds that had never
before been invaded by such a visitant. But so fresh still was his interest
in every triumph of human ingenuity, that it required a long letter to Sir
Joseph Banks, the President of the Royal Society, supplemented by two
postscripts, to disburthen his mind of the sensations and thoughts excited
by the thrilling spectacle. Mingled in this letter with many precise
details of size, weight and distance are the speculations of the Parisians
with respect to the practical uses to which the toy might be put. Some
believed that, now that men might be supported in the air, nothing was
wanted but some light handy instruments to give and direct motion. Others
believed that a running footman, or a horse, slung and suspended under such
a globe, so as to diminish the weight of their feet on the ground to
perhaps eight or ten pounds, might, with a fair wind, run in a straight
line across country as fast as that wind, and over hedges, ditches and even
waters. Still other fantasies were that in time such globes might be kept
anchored in the air for the purpose of preserving game, or converting water
into ice; or might be turned to pecuniary profit as a means of giving
recreation-seekers a chance, at an altitude of a mile, to see far below
them a vast stretch of the terrestrial surface. Already, said Franklin, one
philosopher, M. Pilatre de Rozier, had applied to the Academy for the
privilege of ascending in a larger Montgolfier in order to make certain
scientific experiments. The peasants at Gonesse, however, who had seen the
balloon, cut adrift on the Champs de Mars, fall to the earth, had regarded
it with very different feelings from the citizens of Paris. Frightened, and
conceiving from its bounding a little, when it touched the ground, that
there was some living animal in it, they had attacked it with stones and
knives, so that it was much mangled.
With a subsequent letter to Dr. Price, Franklin enclosed a small balloon,
which his grandson had filled with inflammable air the night before, and
which, after mounting to the ceiling of Franklin's chamber, had remained
rolling about there for some time. "If a Man," this letter suggestively
asks, "should go up with one of the large ones, might there not be some
mechanical Contrivance to compress the Globe at pleasure; and thereby
incline it to descend, and let it expand when he inclines to rise again?"
The same eager curiosity about the balloon was manifested by Franklin in
many other later letters. Another great one, he informed Banks, had gone up
from Versailles. It was supposed to have been inflated with air, heated by
burning straw, and to have risen about two hundred toises; but did not
continue long at that height, and, after being wafted in a horizontal
direction by the wind, descended gently, as the air in it grew cooler. "So
vast a Bulk," said Franklin, "when it began to rise so majestically in the
Air, struck the Spectators with Surprise and Admiration. The Basket
contain'd a Sheep, a Duck & a Cock, who except the Cock receiv'd no hurt by
the fall." Another balloon of about five feet in diameter, the same letter
stated, had been sent up about one o'clock in the morning with a large
lanthorn under it by the Duke de Crillon at an entertainment, given by him,
during the preceding week, in the Bois de Boulogne in honor of the birth of
two Spanish princes. These were but a few of many recent ascensions. Most
interesting of all, however, a new balloon, designed by Messieurs Charles
and Robert, who were men of science and mechanical dexterity, was to carry
up a man.
Another balloon, described by Franklin in one of his letters to Banks, was
open at the bottom, and was fed with heated air from a grate, fixed in the
middle of the opening, which was kept replenished with faggots and sheaves
of straw by men, posted in a wicker gallery, attached to the outside of the
lower part of the structure. By regulating the amount of fire in the grate,
the balloon could be given an upward or downward direction at pleasure.
It was thought, Franklin said, that a balloon of this type, because of the
rapidity and small expense, with which it could be inflated, might be made
useful for military purposes.
Still another balloon described by Franklin in the same letter was one
which was to be first filled with "permanently elastic inflammable air,"
and then closed. It was twenty-six feet in diameter, and made of gores of
red and white silk, which presented a beautiful appearance. There was a
very handsome triumphal car, to be suspended from it, in which two
brothers, the Messrs. Robert, were to ascend with a table for convenience
in jotting down their thermometric and other observations. There was no
telling, Franklin declared, how far aeronautic improvements might be
pushed. A few months before, the idea of witches riding through the air on
a broomstick, and that of philosophers upon a bag of smoke would have
appeared equally impossible and ridiculous. The machines, however, he
believed, would always be subject to be driven by the winds, though perhaps
mechanic art might find easy means of giving them progressive motion in a
calm, and of slanting them a little in the wind. English philosophy was too
bashful, and should be more emulous in this field of competition. If, in
France, they did a foolish thing, they were the first to laugh at it
themselves, and were almost as much pleased with a _bon mot_ or a good
_chanson_, that ridiculed well the disappointment of the project, as they
might have been with its success.
The experiment might be attended with important consequences that no one
could foresee.