I send you enclosed a paper containing some new experiments I have
made, in pursuance of those by Mr. Canton that are printed with my
last letters. I hope these, with my explanation of them, will afford
you some entertainment[66].
In answer to your several enquiries. The tubes and globes we use
here, are chiefly made here. The glass has a greenish cast, but is
clear and hard, and, I think, better for electrical experiments than
the white glass of London, which is not so hard. There are certainly
great differences in glass. A white globe I had made here some years
since, would never, by any means, be excited. Two of my friends tried
it, as well as myself, without success. At length, putting it on an
electric stand, a chain from the prime conductor being in contact
with it, I found it had the properties of a non-electric; for I could
draw sparks from any part of it, though it was very clean and dry.
All I know of Domien, is, that by his own account he was a native of
Transylvania, of Tartar descent, but a priest of the Greek church:
he spoke and wrote Latin very readily and correctly. He set out
from his own country with an intention of going round the world, as
much as possible by land. He travelled through Germany, France, and
Holland, to England. Resided some time at Oxford. From England he
came to Maryland; thence went to New England; returned by land to
Philadelphia; and from hence travelled through Maryland, Virginia,
and North Carolina to you. He thought it might be of service to him
in his travels to know something of electricity. I taught him the
use of the tube; how to charge the Leyden phial, and some other
experiments. He wrote to me from Charles-Town, that he had lived
eight hundred miles upon electricity, it had been meat, drink, and
cloathing to him. His last letter to me was, I think, from Jamaica,
desiring me to send the tubes you mention, to meet him at the
Havannah, from whence he expected to get a passage to La Vera Cruz;
designed travelling over land through Mexico to Acapulco; thence to
get a passage to Manilla, and so through China, India, Persia, and
Turkey, home to his own country; proposing to support himself chiefly
by electricity. A strange project! But he was, as you observe, a very
singular character. I was sorry the tubes did not get to the Havannah
in time for him. If they are still in being, please to send for them,
and accept of them. What became of him afterwards I have never heard.
He promised to write to me as often as he could on his journey, and
as soon as he should get home after finishing his tour. It is now
seven years since he was here. If he is still in New Spain, as
you imagine from that loose report, I suppose it must be that they
confine him there, and prevent his writing: but I think it more
likely that he may be dead.
The questions you ask about the pores of glass, I cannot answer
otherwise, than that I know nothing of their nature; and
suppositions, however ingenious, are often mere mistakes. My
hypothesis, that they were smaller near the middle of the glass, too
small to admit the passage of electricity, which could pass through
the surface till it came near the middle, was certainly wrong: For
soon after I had written that letter, I did, in order to _confirm_
the hypothesis (which indeed I ought to have done before I wrote it)
make an experiment. I ground away five-sixths of the thickness of the
glass, from the side of one of my phials, expecting that the supposed
denser part being so removed, the electric fluid might come through
the remainder of the glass, which I had imagined more open; but I
found myself mistaken. The bottle charged as well after the grinding
as before. I am now, as much as ever, at a loss to know how or where
the quantity of electric fluid, on the positive side of the glass, is
disposed of.
As to the difference of conductors, there is not only this, that some
will conduct electricity in small quantities, and yet do not conduct
it fast enough to produce the shock; but even among those that will
conduct a shock, there are some that do it better than others. Mr.
Kinnersley has found, by a very good experiment, that when the charge
of a bottle hath an opportunity of passing two ways, _i. e._ straight
through a trough of water ten feet long, and six inches square; or
round about through twenty feet of wire, it passes through the wire,
and not through the water, though that is the shortest course; the
wire being the better conductor. When the wire is taken away, it
passes through the water, as may be felt by a hand plunged in the
water; but it cannot be felt in the water when the wire is used at
the same time. Thus, though a small phial containing water will give
a smart shock, one containing the same quantity of mercury will give
one much stronger, the mercury being the better conductor; while one
containing oil, only, will scarce give any shock at all.
Your question, how I came first to think of proposing the experiment
of drawing down the lightning, in order to ascertain its sameness
with the electric fluid, I cannot answer better than by giving you an
extract from the minutes I used to keep of the experiments I made,
with memorandums of such as I purposed to make, the reasons for
making them, and the observations that arose upon them, from which
minutes my letters were afterwards drawn. By this extract you will
see that the thought was not so much "an out-of-the-way one," but
that it might have occurred to an electrician.
"Nov. 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 the particulars
wherein we can already compare them, is it not probable they agree
likewise in this?--Let the experiment be made."
I wish I could give you any satisfaction in the article of clouds. I
am still at a loss about the manner in which they become charged with
electricity; no hypothesis I have yet formed perfectly satisfying me.
Some time since, I heated very hot a brass plate, two feet square,
and placed it on an electric stand. From the plate a wire extended
horizontally four or five feet, and, at the end of it, hung, by linen
threads, a pair of cork balls. I then repeatedly sprinkled water over
the plate, that it might be raised from it in vapour, hoping that if
the vapour either carried off the electricity of the plate, or left
behind it that of the water (one of which I supposed it must do, if,
like the clouds, it became electrised itself, either positively or
negatively) I should perceive and determine it by the separation of
the balls, and by finding whether they were positive or negative; but
no alteration was made at all, nor could I perceive that the steam
was itself electrised, though I have still some suspicion that the
steam was not fully examined, and I think the experiment should be
repeated. Whether the first state of electrised clouds is positive or
negative, if I could find the cause of that, I should be at no loss
about the other, for either is easily deduced from the other, as one
state is easily produced by the other. A strongly positive cloud may
drive out of a neighbouring cloud much of its natural quantity of the
electric fluid, and, passing by it, leave it in a negative state. In
the same way, a strongly negative cloud may occasion a neighbouring
cloud to draw into itself from others, an additional quantity, and,
passing by it, leave it in a positive state. How these effects may
be produced, you will easily conceive, on perusing and considering
the experiments in the enclosed paper: and from them too it appears
probable, that every change from positive to negative, and from
negative to positive, that, during a thunder-gust, we see in the
cork-balls annexed to the apparatus, is not owing to the presence
of clouds in the same state, but often to the absence of positive
or negative clouds, that, having just passed, leave the rod in the
opposite state.
The knocking down of the six men was performed with two of my large
jars not fully charged. I laid one end of my discharging rod upon the
head of the first; he laid his hand on the head of the second; the
second his hand on the head of the third, and so to the last, who
held, in his hand, the chain that was connected with the outside of
the jars. When they were thus placed, I applied the other end of my
rod to the prime conductor, and they all dropped together. When they
got up, they all declared they had not felt any stroke, and wondered
how they came to fall; nor did any of them either hear the crack, or
see the light of it. You suppose it a dangerous experiment; but I
had once suffered the same myself, receiving, by accident, an equal
stroke through my head, that struck me down, without hurting me: and
I had seen a young woman that was about to be electrified through the
feet (for some indisposition) receive a greater charge through the
head, by inadvertently stooping forward to look at the placing of her
feet, till her forehead (as she was very tall) came too near my prime
conductor: she dropped, but instantly got up again, complaining of
nothing. A person so struck, sinks down doubled, or folded together
as it were, the joints losing their strength and stiffness at once,
so that he drops on the spot where he stood, instantly, and there is
no previous staggering, nor does he ever fall lengthwise. Too great
charge might, indeed, kill a man, but I have not yet seen any hurt
done by it. It would certainly, as you observe, be the easiest of all
deaths.
The experiment you have heard so imperfect an account of, is merely
this: I electrified a silver pint can, on an electric stand, and then
lowered into it a cork ball, of about an inch diameter, hanging by a
silk string, till the cork touched the bottom of the can. The cork
was not attracted to the inside of the can as it would have been
to the outside, and though it touched the bottom, yet, when drawn
out, it was not found to be electrified by that touch, as it would
have been by touching the outside. The fact is singular. You require
the reason; I do not know it. Perhaps you may discover it, and then
you will be so good as to communicate it to me[67]. I find a frank
acknowledgment of one's ignorance is not only the easiest way to get
rid of a difficulty, 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 every thing, and so undertake to explain
every thing, often remain long ignorant of many things that others
could and would instruct them in, if they appeared less conceited.
The treatment your friend has met with is so common, that no man
who knows what the world is, and ever has been, should expect to
escape it. There are every where a number of people, who, being
totally destitute of any inventive faculty themselves, do not readily
conceive that others may possess it: they think of inventions as of
miracles; there might be such formerly, but they are ceased. With
these, every one who offers a new invention is deemed a pretender: he
had it from some other country, or from some book: a man of _their
own acquaintance_; one who has no more sense than themselves, could
not possibly, in their opinion, have been the inventor of any thing.
They are confirmed, too, in these sentiments, by frequent instances
of pretensions to invention, which vanity is daily producing. That
vanity too, though an incitement to invention, is, at the same time,
the pest of inventors. Jealousy and envy deny the merit or the
novelty of your invention; but vanity, when the novelty and merit
are established, claims it for its own. The smaller your invention
is, the more mortification you receive in having the credit of it
disputed with you by a rival, whom the jealousy and envy of others
are ready to support against you, at least so far as to make the
point doubtful. It is not in itself of importance enough for a
dispute; no one would think your proofs and reasons worth their
attention: and yet, if you do not dispute the point, and demonstrate
your right, you not only lose the credit of being in that instance
_ingenious_, but you suffer the disgrace of not being _ingenuous_;
not only of being a plagiary, but of being a plagiary for trifles.
Had the invention been greater it would have disgraced you less;
for men have not so contemptible an idea of him that robs for gold
on the highway, as of him that can pick pockets for half-pence
and farthings. Thus, through envy, jealousy, and the vanity of
competitors for fame, the origin of many of the most extraordinary
inventions, though produced within but a few centuries past, is
involved in doubt and uncertainty. We scarce know to whom we are
indebted for the _compass_, and for _spectacles_, nor have even
_paper_ and _printing_, that record every thing else, been able to
preserve with certainty the name and reputation of their inventors.
One would not, therefore, 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.