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SECTION VIII
Observations on atmospheric electricity collected by the
flame of a candle.
Before I describe my observations on this
subject of enquiry, it may be proper to mention
such theory of atmospheric electricity as appears
to me consonant to the general operations of nature,
and deduced from the most rational systems of
others, my own observations, or the contents of the
foregoing sections, which the intelligent reader will
easily apply to this purpose.
The intention of beginning with the theory is to
give the reader, (who may not have attended to
atmospheric electricity) an opportunity of seeing to
more advantage the principals which these observations
tend to confirm or illustrate, and thereby render
them more interesting and pleasant.
Atmospheric electricity may be principally considered
as it appears in two states of the air, that is
transparent and cloudy.
1st. The transparent or clear air always contains a
great quantity of water in solution, and is generally
found to be in a state of constant positive electrification,
yet not always of the same degree of intensity,
nor is the atmosphere every where in the same
state, for the higher regions from their more perfect
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insulation, are more strongly electrified than the
lower strata of air whence the earth is constantly
reabsorbing this fluid, and the invisible vapours are
undoubtedly more or less dense in different places
according to the quantity of evaporation and condensation,
depending on the variations of heat and
cold, so that irregular spaces of air, perhaps in the
form of clouds, yet invisible, will be electrified
positively or negatively; and to restore the equilibrium,
the appearances called falling stars are produced.
Or if the equilibrium between much larger tracts of
air is to be restored, large meteors such as that of
the year 1783 fly with astonishing brilliance and
rapidity from one region of the air to another.
The aurora borealis is another electrical appearance
frequently seen in a transparent atmosphere,
yet it is sometimes seen when there are clouds, and
is probably owing to the diffusion of electricity in
the highest and most rarified part of the atmosphere,
where the air is not sufficiently dense to exhibit the
electrical fluid in the form of corruscations or balls
of fire.
2ndly. When vapours are sufficiently condensed
to become visible, the intensity of their electrification
increases, and if the clouds thicken speedily,
their sensible electrical atmosphere sometimes
extends to the distance of several miles. This extensive
atmosphere will act powerfully on the lower
strata of vapour, (which may be considered as having
an imperfect connection with the earth) and
induce a negative state whose intensity will continue
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increasing with that of the super-incumbent cloud,
till the equilibrium be restored by tremendous claps
of thunder, with vivid corruscations of lightning.
And if the cloud happens to be low, the earth itself
becomes its immediate opponent, and is sometimes
violently struck to the injury or destruction of its
vegetable or animal inhabitants.
These are the chief and most striking effects of
atmospheric electricity, and to account for them on
the known principles of this fluid is the business of
my present attempt.
The first and most difficult part of this investigation
is to ascertain the general cause of sensible electricity
in the air, and explain the particular manner
in which it is absorbed from the earth. But from
the late satisfactory experiments of Messrs Volta,
Lavoisier, De la Place, and De Sauffure, the evaporation
of water by the sun's heat may be confidentially
assigned as the true general cause, and this opinion
I hope the reader will find in some measure strengthen'd
by the experiments contained in section the
fourth. And from the experiments on approximating
surfaces, and on adhesive electricity in the
sixth and seventh sections,
I would infer that when water
is raised into the air by means of heat, electricity
adheres more copiously under such circimstances to
each rising particle from the general laws of the
attraction of cohesion, and the very great elasticity of
the electrical fluid; for a rising particle of water
may be considered as in the situation of the copper
plate, section 6th, experiment 3d and
4th, that
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is surrounded with air except that it is connected
with the earth by one point of contact. And if
there is a difference between air and water as to
their elective attraction of electricity, which from
numerous corresponding facts may easily be admitted,
it follows that the smaller the particles of water
are, the more they come into contact with air, that
is their surfaces bear a greater proportion to their
solidity, and consequently they partake the more of
the property of air as to their attraction of electricity;
or the surface of air in contact with the water, has
in this situation, the opportunity of absorbing electricity
thro' the above-mentioned touching point:
which electricity from the circumstances of approximation
and contact, may be condensed and the particle
of water be positively electrified tho' uninsulated.
It is for the sake of perspicuity that the vapour
is here considered as rising in the form of small
globular particles: but however that may happen, the
electrical adhesion will probably be the same: for if
the process of evaporation shou'd not consist in the
ascension of globular particles raised by heat, but
that it consists in a chemical combination of heat,
air, and water, which instantaneously form a transparent
fluid, this compound substance may have a
greater adhesive affinity with electricity than the
surface whence it rises, and therefore becomes positively
electrified. And this last supposition is
considerably illustrated by the experiments contained in
sect.4th, wherein it is seen that the mixture of
various mineral, vegetable, and animal substances,
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with the evaporating water changed it adhesive
electricity.
Vapour thus ascending electrified, and being
combined with air and heat so as to form a perfectly
transparent fluid, is in its weakest positive state,
till the heat passes off either by diffusion in the
circumambient air, by two currents of different
degrees of rarity passing in contrary direction, or by
the higher part of the atmospher moving with
greater or less velocity than the lower, each current
being more or less cold than the other. In any of
these situations the vapour will be condensed and
increase the intensity of its positive charge, and
some such causes acting at all times, produce a constant
positive electrification of the atmosphere, even
before the degree of condensation is sufficient to
destroy its transparency.
During a space of fifteen years, F Beccaria never
observed a serene atmosphere to be negatively
electrified, except in four instances, when there was
great reason to believe it proceeded from the influence
of distant clouds. See his treatise on artificial
electricity.
When this kind of condensation happens in the
higher and more insulated part of the atmosphere,
where no equilibrium can be restored by an insensible
diffusion of electricity, nor by striking suddenly
into the earth, and when the intensity of this electricity
is increased beyond the capacity of the
vapour to which it is attached, it is formed into balls
of fire; for any fluid will form itself into a globular
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NEW EXPERIMENTS
figure from its own attraction of cohesion, if this
effect be not prevented by adhesion to other
substances. These balls of highly condensed electricity
then move off towards those parts of the air which
are least electrified, diffusing electricity as they pass,
till they are wholly dissipated and consequently
disappear. This dissipation may be plainly distinguished
by a train of fire which often follows the meteors
called falling stars.
The same causes may be supposed to occasion the
larger meteors, which being collected from and
dissipated in more extensive regions of air, are more
luminous. and attended with one circumstance
which might be expected from a very great accumulation
of electricity, that is a division of the ball
into several parts towards the end of its course.
Whoever has seen electricity emitted from a large
electrical machine, thro' a long and capacious
exhausted tube of glass, may perceive a striking
similarity between this experiment and the aurora borealis,
and may reasonably conjecture that the electrical
equilibrium being destroyed in the highest and
most rarified part of the atmosphers is the occasion
of this appearance, and that it is very high is proved
by the converging direction of the streams; and
since the streams sometimes appear to move about
considerably, and to indicate an uncommon degree
of electrification, I have frequently been induced to
examine the state of the air with a very sensible
electrometer, during a very luminous aurora borealis,
but cou'd not distinguish either an extraordinary
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quantity or motion of electricity. Pehaps other
situations might be more favourable for such
observations, and hence others have more confidently
affirmed that their apparatus has been affected
by it.
When the air has lost more of its heat and the
condensed vapour becomes visible so as to form
clouds or mists, the intensity of its electrification is
increased, because the water is now formed into
small globules whose surfaces proportionally lessen,
as the globules increase in diameter, and from Dr
Franklin's experiment of the can and chain it has
been long known that lessening the quantity of surface
exposed to air, increases the intensity of electrification.
Mists and fogs which are only thin clouds
near the earth are generally found to be electrified
strongly positive, so that a kite having a metallic
string and raised in misty weather will produce pungent
sparks. But when clouds fly over a transparent
air, and are in a still stronger state of electrification,
it often happens that their atmosphere drives
into the earth the electricity contained in the lower
stratum of vapour, or that contained in some part
of the cloud which from its situation can be most
easily discharged thro' its imperfectly conducting
connection with the earth.
A part of the cloud thus render'd negative is
frequently separated from the positive part, by the
different currents of wind, or when the higher part
of the cloud moves with more or less velocity than
the lower, in this case the negatived vapour will
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produce a sensible atmosphere, and hence the clouds
appear sometimes positive and sometimes negative.
To illustrate this effect of strong electrical atmospheres,
the reader may try experiment the 8th, sect. 2d.
And that a negative atmosphere will
become sensible even upon a body floating in air
whose positive state is the only cause of such atmosphere,
is easily tried by first causing the air of a
room to be strongly electrified positively, and then
a small slip of gold leaf thrown into the air will
acquire a negative state as it leaves the hand, and
will be repelled by the approach of a finger or other
conductor. In this experiment the finger has a
sensible negative atmosphere as well as the gold leaf,
tho' it be not insulated.
In summer altho' the hygrometer indicates a drier
air, yet there is undoubtedly more evaporation, and
therefore more water combined with or diffused in
the atmosphere. The surface of the earth is hotter,
and yet the higher part of the atmosphere, owing
to its transparancy and distance from the earth is not
heated in the same proportion. In short every
natural process is quickened or retarded by the active
influence of the sun, and if vapours can now be
more suddenly raised, they may also be more suddenly
condensed, and under these and other favourable
circumstances, the clouds become electrified
to a much higher degree of intensity, till the
equilibrium of the differently electrified strata, is
restored by explosions termed thunder and lightening.
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The concourse of two oppositely electrified clouds
has sometimes been thought the immediate cause of
thunder, and it is certainly possible that such clouds
may now and then be driven by opposite currents
so as to cause an explosion, but I think it is more
agreeable to the most common appearances of the
clouds to account for it by the extensive and powerful
influence of electrical atmospheres, whereby the
several parts of the cloud or surface of the earth are
render'd positive or negative, as explained above;
for it will not otherwise be easy to account for the
quick and frequent succession of explosions which
are perceived in a single and distinct cloud, every
part of which is apparently moving in the same
direction. But on the supposition of a negative
stratum, occasioned by a powerful positive atmosphere,
as long as a rapid condensation of water takes place,
so long may a repetition of explosions be expected.
The following experiments may serve to illustrate
the process of atmospheric explosions as far as relates
to the influence of powerful electrical atmospheres.
Let two slips of gold leaf or rather white Dutch
metal be fasten'd to a brass ball suspended by a silk
string, or other insulating substance. Bring the
brass knob of a charged bottle towards the points
of the metallic slips till they become charged with
electricity, which will cause them to be repelled each
way from the knob of the bottle and stand as in
plate 3d, fig.3d. Continue to hold the bottle in
the same position during a few seconds, and one of
the slips will bend towards the knob of the bottle
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fig.4, and strike it suddenly, then it will stand
repelled till its electricity be again dissipated. In this
manner it will continue to repeat the stroke as long
as a sufficient quantity of electricity remains in the
bottle, unless the air be very dry, and then this
experiment may fail, which with me has only happened
twice.
After this short account of my ideas of atmospheric
electricity, I now proceed to describe the
instruments I have made use of in making observations.
The most common apparatus hitherto used has
chiefly consisted of high pointed and insulated
conducting rods, or wires extending from the place of
observation to the top of an high building or steeple,
and connected with an electrometer, or the small
and insensible communications of electricity have
been collected by means of Mr Volta's condenser.
But these instruments are generally either not sufficiently
sensible, or they can only shew the state of
atmospheric electricity at intervals, whence the
observor loses the opportunity of watching the momentary
and interesting change which happens in several
states of the atmosphere, especially during the
passage of thunder clouds.
In sect. 2d exp. 20th, 31st
and 32d, it was
found that the flame of a candle was very useful in
rendering the atmospheric electricity sensible when
it could not be perceived by means of points; this
I believe it does because the effluvium of the candle,
which is of a conducting nature, becomes combined
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with air so as to form a very compleat union, and
as the rarified air so combined with phlogistic effluvium
rises upwards, it is continually succeeded by
a fresh quantity, and hence the apparatus has the
opportunity of absorbing electricity much more
copiously than the sharpest points. Considering this
advantage I provided a deal rod about 10 feet long,
(see plate iii. fig.2d,)and after the smaller end was
well dried it was fastened into a long tinn'd iron
funnel with cement, so that the funnel did no where
come within half an inch of the end of the rod; by
this means it is kept dry, and the funnel is not so
liable to be accidentally broken off as if it was
insulated by means of glass. At the small end of the
funnel is suspended the ring of a chain which
supports a small lantern, containing a lighted candle.
To the lower and broad edge of the funnel a softened
brass wire is fastened, which is about the length of
the whole rod, and at the lower end is hooked to a
small ring near the thick end of the rod, that the
wire may not be liable to accidents when the instruments
is [sic] taken down. When this apparatus is used,
a window is opened in the highest room of the house,
and the rod is placed upon one strong nail and
under another, on one side of the casement, so that
the lantern is elevated about 50 degrees. Near the
place to which the rod is fastened is a hole in the
window frame of sufficient width to receive a tube
of glass cover'd with sealing wax, on the end of
which is a bent wire. The hook of the brass wire
is then taken from the ring, and hooked upon this
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NEW EXPERIMENTS
insulated bent wire, which stands at a proper height
to be connected with the cap of a gold leaf electrometer,
standing upon a board under the wire, and
that the brass wire may not be too much agitated
by the wind a ball of lead is hung upon it. In this
situation it is plain that the atmospheric electricity
collected by the candle will come down the brass wire
and be communicated to the cap of the electrometer,
or to any other instrument. But as it very seldom
happens that the gold leaf does not diverge when
this apparatus is elevated, there is little occasion to
make great use of a condenser or doubler, nor even of a
candle when there are large clouds passing over or
rain falling.
OBSERVATION I
May 24th, 1787. Several heavy clouds passed
from the N W and the above described apparatus
being elevated, the gold leaf diverged sometimes
positively and sometimes negatively; at last a blacker
cloud approached and rain began to fall, which
caused the gold leaf to strike the sides of the electrometer
negatively with increasing velocity till a
flash of lightening and clap of thunder happened,
and at the instant of the flash the gold leaf suddenly
started open and then closed, and gradually open'd
positively striking the sides about ten times, it then
slowly closed and open'd negatively, and again struck
the sides with increasing velocity till the second flash
caused the same convulsive motion and sudden change
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of its electricity; this was repeated several times
during the passage of the cloud. When the thunder
was more distant the opening of the gold leaf
was less but yet very sudden, and at last the gold
leaf frequently started open when no thunder was
heard, or flash seen.
OBSERVATION II
May 26th, 1787. Several showers passed over
and electrified the apparatus first positively as the
cloud approached, then it changed about the middle
of the shower and ended negatively.
OBSERVATION III
May 28th, 1787. The wind high and N W.
A shower of rain came on which electrified the
apparatus first positively, the gold leaf continuing to
strike the sides till the rain abated, then it became
negative and it continued to strike more slowly till the
rain entirely ceased, when it again changed and stood
at about a quarter of an inch positive, and the sky
became quite clear.
OBSERVATION IV
June 7th, 1787. Wind S W and brisk. A
shower coming on caused the gold leaf to strike the
sides first negatively, then positively, and at the
end of the shower again weakly negative.
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OBSERVATION V
June 8th, 1787. The sky was entirely overcast
and small rain fell for several hours, which electrified
the apparatus positively.
OBSERVATION VI
June 25th, 1787. Wind W. Barometer 29.
Thermometer in the house 64°. A little before one
o'clock in the afternoon, the apparatus was elevated
before the approach of a distinct and heavy cloud.
The gold leaf diverged negatively slowly increasing
till it began to rain, it then struck the sides and
continued striking till the rain ceased, it then changed
to positive and continued striking whilst fair; after
some time it again became negative, and struck
quicker whilst it again rained, and some distant
thunder was heard without moving the electrometer.
Expecting more thunder, I hung up my watch near
the apparatus that I might note down the time and
changes of electricity, as they occured during the
passage of the cloud.
Hour Min
1 7 Raining, electrometer striking quick negatively.
- 10 Electrometer striking more slowly.
- 12 Now changed to positive & opening slowly.
- 13 Thunder heard, striking slowly positive.
- 14 Very quick positive, yet raining.
- 15 More slowly positive.
- 17 Changing to negative.
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Hour Min
1 18 Quick negative
- 20 Thunder at a distance, still striking negative.
- 23 Still striking negative, raining slowly.
- 26 Still striking quick negative.
- 27 The gold leaf quite closed.
- 27½ Striking positively, yet raining slowly.
- 29 More slowly positive.
- 30 Rain ceased. Electrometer opening about an inch positively.
- 34 No sensible electricity. Some drops of rain falling.
- 39 Gold leaf open'd about half an inch positive, but decreasing.
- 40 Suddenly open'd positive, and then slowly striking. Heavy drops.
- 43 Decreasing positively. Raining.
- 45 Electricity insensible. Raining slowly.
- 46 Slowly opening negatively.
- 47½ Slowly opening positively.
- 48 An inch wide positive.
- 49 The gold leaf agitated and positive.
- 49½ Still agitated but changed to negative.
- 50 Opening negatively by starts till it strikes quick. Raining fast.
- 52 Ceases to strike, decreasing fast.
- 53 Changed to positive.
- 54 Striking positively.
- 55 The gold leaf struck the glass instead of the tin-foil.
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Hour Min
1 56 Striking very quick positively.
- 57 Slower and then very quick, still raining very fast.
- 59 Distant thunder. Changing to negative.
2 0 Striking quick negatively.
- 1 Decreasing negatively.
- 1½ Opening positively to the distance of an inch.
- 2 Then changed to negative, and striking quick.
- 4 Changed to positive, and then striking quick.
- 6 Changing to negative.
- 7 Striking quick negatively.
- 8 Striking quick negatively.
- 9 Striking quick positively.
10 Still quick positively, and raining fast.
Distant sky brighter.
- 11 More slowly positive.
- 12 Again quicker positive.
- 13 Still quick positive. Sky clearing yet raining.
- 14 Decreasing positively.
- 15 Opening negatively. Rain shower and sky clearer.
- 16 Standing wide negatively.
- 16½ Decreasing negative.
- 18 Rain ceased. Just sensibly positive.
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Hour Min
2 18½ Sun shining, and the gold leaf open'd to
half an inch negatively.
- 20 A quarter of an inch pos. Sky clear.
In this observation there are 10 changes of electricity
in less than an hour and a half.
OBSERVATION VII
July 2d, 1787. Wind N W. Barometer 29.
45. Thermometer 68. Six o'clock in the evening.
Unequal clouds covering the whole horizon.
which caused a divergency of the elecrometer of
about half an inch positive.
OBSERVATION VIII
July 14th, 1787. About two o'clock in the
afternoon. Wind N E. Heavy showers but clouds
uneven. The gold leaf opened negatively, and
moved irregularly till it slowly struck the side, and
as the rain abated it opened less, but never changed
to positive.
OBSERVATION IX
July 15th, 1787. About half past seven in the
evening. Wind S E. An heavy shower of rain
falling, the gold leaf struck the sides quick positively,
and continued to do so about 10 minutes; it
then became weakly negative, and stood at half an
inch negative when the rain ceased.
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OBSERVATION X
July 15th, 1787. About eight o'clock in the
evening another shower came on which began to
open the gold leaf positively, increasing very slowly
till it struck the sides whilst the rain increased, and
when the rain came down quickest, it gradually
changed to negative. The clouds then appeared
very uneven, and often changed the electricity till
the observations were discontinued.
OBSERVATION XI
July 17th, 1787. About 6 o'clock in the evening.
Wind N W. A shower of rain electrified
the apparatus weakly negative during the space of
about half an hour without changing.
OBSERVATION XII
July 25th, 1787. About one o'clock in the
afternood. Wind W. A heavy cloud approached
and electrified the apparatus negatively a considerable
time without rain; at last some drops falling the
gold leaf struck the sides, and continued to do so
till the rain ceased without changing to positive.
The weather had been rainy for some days.
OBSERVATION XIII
August 4th, 1787, Ten o'clock in the morning.
Wind W. Barometer 29.15. Sky very clear.
The gold leaf opened just sensibly positive.
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OBSERVATION XIV
August 12th, 1787. Wind W. Barometer 29.1.
Therm. 62°. The sky was overcast with uneven
clouds, and a heavy cloud approaching it rained
slowly, which gradually opened the gold leaf to the
distance of an inch positively, then raining faster it
suddenly collapsed and changed to negative, opening
to half an inch whilst the rain ceased.
Two other clouds soon followed, which began
positively and ended negatively as before.
A very extensive cloud succeeded the last and
open'd the electrometer positively, which continued
striking a short time; then it changed and struck
negatively during about half the rain; it then changed
and struck positively during the remainder of the
shower, and when the rain ceased it open'd about
half an inch negatively, where it stood for a few
minutes and then collapsed, the sky clearing.
OBSERVATION XV
About five o'clock the same day. The wind
N W. A shower began strongly positive and ended
negatively as before. About six o'clock some
uneven clouds passed over and the electrometer
diverged negatively without rain, then rain falling it
struck negatively a long time, then a heavier cloud
approaching it changed and struck very quick positively,
till the rain abated and the cloud was nearly
gone, when it again changed and was weakly negative
till the rain entirely ceased.
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OBSERVATION XVI
August 14th, 1787. About noon. Wind S W.
Very extensive clouds with small drizling rain, which
continued with very little variation about half an
hour, it then rained somewhat faster and the electricity
changed and continued about the same time
negative.
OBSERVATION XVII
August 16th, 1787. Nine o'clock in the morning.
Wind quite calm. A thick mist. Electrometer
open'd half an inch positively.
OBSERVATION XVIII
August 18th, 1787. Half past twelve o'clock.
Wind S W. Thin white clouds have been passing
over all morning. A distinct black cloud approached
and some rain fell before the apparatus was
elevated, the electrometer open'd positively and
continued opening but not striking till very heavy
drops fell, it then changed and struck the sides
negatively till the rain ceased. Its velocity abated
when it was fair, but continued striking for about
five minutes, it then decreased but continued open
negatively till another cloud approached, it then
open'd positively about half an inch, when it began
to rain slowly, as the rain fell it open'd a little
wider.
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Hour Min
12 45 About an inch positive. Rain ceasing
and gold leaf collapsing.
- 47 Electricity insensible.
- 47½ Opening slowly negative. Cloud approaching nearer.
- 48 A few large drops falling. Half an inch negative.
- 50 Still half an inch negative, but drops ceased.
- 51 Decreasing. The clouds passed off, and
another approaching.
- 57 Still just sensibly negative. Cloud large
and likely to rain.
- 59 Beginning to rain. Opening to half an
inch negative, and then striking.
1 0 Raining faster. Striking about twice in a second.
- 1 Rain abated, yet striking negatively.
- 4 Yet striking negatively, but little rain.
- 5 More rain. Electricity decreasing. Cloud
about half over.
- 6 Electricity now increasing.
- 6½ Striking negatively.
- 7 Striking quick negatively, yet but little rain
- 8 Still quick negative. More rain.
- 10 So quick as to keep the gold leaf trilling
against the sides. Heavy rain.
- 12 Rain suddenly abating. Ceased to strike,
and decreasing.
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Hour Min
1 13 Changed to positive, striking slowly then
quick. Few drops.
- 14 Trilling positively.
- 14½ Slower positive. Very few drops of rain.
- 15 Quite fair, yet striking slowly positive.
Clear sky over.
- 17 Yet striking slowly positive.
- 19 Ceased striking, and decreasing. Sun shining.
- 20 Wide positive divergency, but decreasing
very slowly.
- 24 Half an inch positive.
- 25 Just sensibly positive.
- 27 Insensible. Sky clear.
These clouds began and ended positively, and
therefore it may be concluded that their proper state
was negative, which occasioned on all sides an
influential positive atmosphere.
OBSERVATION XIX
August 25th, 1787. Twelve o'clock. Wind N.
Barometer 28.63. Having rained all day, the
electrometer open'd weakly negative, and sometimes
changed to positive for a short time, but was mostly
negative.
OBSERVATION XX
August 27th, 1787. Two o'clock in the afternoon.
Wind N. Barometer 29.3. A shower
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came on which opened the gold leaf slowly positive,
which continued opening and closing whilst most of
the rain fell, but did not strike the side. When
the rain was nearly over it changed to negative, and
then struck the sides for a considerable time after
the rain had ceased.
OBSERVATION XXI
Dec.18th, 1787. Eleven o'clock in the morning.
Mist covering the tops of the hills, which it
had done for several days, sometimes descending
into the valleys. The gold leaf diverged strongly
positive: but upon the falling of some small rain it
was found negative. The same happen'd on the
20th.
OBSERVATION XXII
Dec. 25th, 1787 Wind E. Small snow falling
all day. Gold leaf diverged strongly positive, tried
several times.
OBSERVATION XXIII
Dec. 27th, 1787. Wind N E. Snow melting.
A few white clouds. Electricity strongly positive.
OBSERVATION XXIV
Jan. 1st, 1788. Wind S. A very thick mist,
yet its electricity was but sensibly positive, tho'
whilst the mist was accompanied with frost and with
an east wind it had been for several days, so strongly
positive as to be very sensible without a candle.
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OBSERVATION XXV
Jan. 2d, 1788. Wind S. Small rain. Electricity
negative.
Jan. 6th, 1788. Wind S. Small rain. Electricity
negative.
OBSERVATION XXVI
Jan. 16th, 1788. High west wind. A cloud
passed over and some sleet fell. The electrometer
diverged strongly positive. The sky then clearing
it became strongly negative, and decreasing changed
to a weak positive when the sky was quite clear.
OBSERVATION XXVII
Feb.5th, 1788. Wind E. Thick mist on the
hills, with small rain most of the day. Electricity
negative except when the sky appear'd brightening,
it then became positive a short time, and then when
more rain fell it became again negative, and continued
so most of the day. Constant rain seems
mostly negative, because it probably forms a more
extensive connection with the earth by moisture
which weakens the positive and higher electricity,
and strengthens the influential negative atmosphere.
OBSERVATION XXVIII
Feb.19th, 1788. Wind S W and gentle snow
continued falling for several hours. The electrometer
diverged about an inch positively.
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ON ELECTRICITY
OBSERVATION XXIX
Feb.20th, 1788. Wind E. No frost but a
very thick mist. Gold leaf struck the sides
positively.
OBSERVATION XXX
March 5th, 1788. Wind S W. and gentle snow
continued falling from noon to five o'clock, the
apparatus was eleveated five times, and the gold leaf
struck the sides positively.
OBSERVATION XXXI
March 15th, 1788. Wind N E. Snow had
lain on the ground about a week, with hard frost,
but now it was thawing and there fell some sleet.
The gold leaf slowly struck the sides negatively.
OBSERVATION XXXII
March 18th, 1788. Wind N E. brisk. Overcast
but fair. Electricity insensible with the candle,
never observed so weak before.
OBSERVATION XXXIII
March 21st, 1788. Wind W. One o'clock.
A shower of hail came om which caused the gold
leaf to strike violently positive. A little before the
shower ceased it changed and struck negatively, and
continued negative after the hail ceased and the sun
shone for more than half an hour, slowly decreasing.
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NEW EXPERIMENTS
OBSERVATION XXXIV
March 21st, 1788. Wind W. Three o'clock
in the afternoon. A large cloud succeeded the last,
the negative state of the air having continued till
the cloud approached, which changed the electricity
to positive, when being engaged this cloud could
not be examined. At four o'clock a very large
cloud came with rain, the electricity was found
strongly negative, the electrometer could not come
within 12 inches of its usual position without
endangering the gold leaf; towards the end of the shower
it changed from negative to positive several times.
Once the change only lasted whilst the gold open'd
and closed. At last it continued to strike negatively
whilst the sky cleared, decreasing for about a
quarter of an hour, it then changed to positive now
fair, but a cloud approaching.
Hour Min
4 30 Electricity positive. Half open decreasing.
- 31 Closed. The cloud approaching fast.
- 33 Opening negatively. The edge of the
cloud nearly over.
- 34 Still opening negative very slowly. No
rain, very calm.
- 38 Little more opened. Cloud appears more broken
- 41 Slowly decreasing.
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ON ELECTRICITY
Hour Min
4 43 A few drops of rain. Gold leaf almost closed.
- 45 Quite closed. No rain. Sunshines thro'
a part of the cloud.
- 48 Still closed.
- 50 Opening positively. No rain.
- 56 Standing at half an inch positively.
5 0 Slowly decreasing. Cloud appears heavier.
- 4 Quarter of an inch positive. No rain.
cloud still blacker.
- 9 A few drops of rain. Electricity the same.
- 17 No drops. Electricity rather increased.
Cloud coming slowly.
- 19 Gold leaf diverges half an inch positive.
No rain.
- 21 Gold leaf rather decreasing.
- 23 Quite closed. No rain. Cloud heavy.
- 25 Opening negative. No rain.
- 26 Half an inch negative.
- 29 Rather wider. No rain. Cloud still over.
- 30 Closed. Darker.
- 31 Opening positively.
- 32 Strikes slowly.
- 33 Striking quick positive, yet no rain.
- 34 Electrometer strikes at twelve inches from
the wire.
- 35 A little rain.
- 36 A clap of thunder, and sudden start of
gold leaf, yet positive.
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NEW EXPERIMENTS
Hour Min
5 37 Raining faster. Still positive.
- 38 Hailing fast, still positive, and striking
at twelve inches distant.
- 39 Remarkable strong hail, striking quick at
twelve inches.
- 42 Still hailing. Electricity ditto.
- 44 Still large hail. Electricity weaker.
- 45 Changed quick to negative, and striking
at twelve inches distance.
- 46 Hail less. Electricity rather weaker.
- 47 Hail ceased. Electricity only opens
negatively at three inches distance.
- 49. Electrometer in contact with the
wire now positive.
- 50 Gold leaf just strikes the sides positively.
- 52 A flash of lightning and crack quickly
following. A sudden stroke of the
gold leaf which changed it to negative.
- 54 Striking negatively.
- 55 Electrometer removed to the distance of
12 inches, where it strikes quick negatively.
- 56 Striking more slowly negative.
6 0 Electrometer replaced striking negatively. Stll fair.
- 1 Striking rather slower.
- 3 Still slower, and yet fair.
- 5 Gold leaf stands about an inch wide negatively.
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ON ELECTRICITY
Hour Min
6 7 Closed, and then opening positively.
- 8 One inch pos. Small rain falling.
- 9 Strikes the sides positively.
- 11 Decreasing. Rain ceased.
- 12 Closed. Quite fair.
The first thunder clap did not change the electricity;
the second changed it from positive to negative,
contrary to former observations; this must
depend in some measure on the distance.
OBSERVATION XXXV
April 13th, 1788. Nine o'clock in the morning.
Wind S W. Sky perfectly clear having been
without clouds since the evening before. The gold
leaf diverged about half an inch positively.
At twelve o'clock the same day the divergency
was only about a quarter of an inch, and the same
at eleven o'clock at night.
OBSERVATION XXXVI
April 30th, 1788. The wind N E and very
gentle. An hygrometer of whipcord, which moved
in a space of 16 inches, marked in inches and eights
moist and dry, reckoning up and down from the
middle of the space, stood at 67/8 dry. The apparatus
was elevated at 3 o'clock, afternoon, and the
gold leaf opened half an inch positively. At half
past 8 o'clock the hygrometer was risen about an
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NEW EXPERIMENTS
inch, and the gold leaf open'd so wide as nearly to
strike the side. The weather all the time quite serene.
The falling of the dew appeared to increase
the divergency of the gold leaf.
OBSERVATION XXXVII
May 1st, 1788. Seven o'clock in the morning.
Wind N E gentle, serene and perfectly clear.
The hygrometer 37/8 dry. The gold leaf nearly
struck the side positively.
About 11 o'clock the same day, hygrometer 53/8
dry, the gold leaf now opened only half an inch positively,
still clear and hot.
At 12 o'clock the wind changed to S W yet
very clear and hot. The divergency was less than
quarter of an inch. Hygrometer 67/8 dry.
At 1 o'clock, the wind S. Divergency 1-16th
of an inch.
At 2 o'clock the electricity quite insensible, clear,
and very hot. Hygrometer 7 dry.
At 3 o'clock the gold leaf open'd 1/8 of an inch
positively. A few white clouds appear'd. Hygrometer
73/8 dry.
At 5 o'clock, clouds somewhat darker. Divergency
quarter of an inch. Hygrometer 73/8 dry.
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ON ELECTRICITY
At 7 o'clock, fewer clouds, very calm. Divergency
half an inch. Hygrometer 61/8 dry.
Half past 8 o'clock. Hygrometer 56/8ths dry.
Divergency only quarter of an inch. Sky now clear.
Eleven o'clock at night. Hygrometer 56/8ths
dry. Clear and calm. Divergency half an inch.
OBSERVATION XXXVIII
May 5th, 1788. Half past 4 afternoon. Wind
N E. Having been clear all day. Hygrometer
64/8ths dry. Divergency ¼ inch positive.
At nine o'clock in the evening. Hygrometer
55/8 dry. Barom. 29.3. Clear and calm. The
gold leaf slowly strikes the sides positively.
OBSERVATION XXXIX
May 6th, 1788. Near twelve o'clock at night.
Barom. 29.2. Hygrometer 53/8 dry. An heavy
shower of rain lasted about half an hour, during
which the gold leaf continued striking positively,
and after the rain ceased it continued a long time
striking positively, and never changed to negative.
Since the weather had been so long dry, it is probable
that the air was not sufficiently moist to conduct
away the electricity, which wou'd have been
otherwise repelled by the atmosphere of the cloud.
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NEW EXPERIMENTS
OBSERVATION XL
May 17th, 1788. The wind N E whence it
had blown about a week without rain. Hygrometer
5 dry. Barom. 29.2. The air undoubtedly
very dry. The slips of Dutch metal were suspended
in the middle of a room as before described, and
when the charged bottle was presented the slips of
metal stood diverging and cou'd not be made to
strike the knob as usual, which shews that a certain
degree of moisture in the air is necessary to this
experiment.
OBSERVATION XLI
May 19th, 1788. Barom. 29.15. Hygrometer
5 dry. Clouds moving slowly from the north
and thickening in the south. at half past 2 o'clock
the apparatus was elevated, and the electrometer
struck the sides slowly positive for some time, then
stood still at about an inch wide, and then started
closer or wider several times, which was probably
occasioned by distant thunder.
Hour Min
2 45 A sudden change to negative, which
open'd half an inch, and then closed
and became positive.
- 50 Opening and closing positively. Darker
in the south.
- 55 About quarter of an inch positive.
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ON ELECTRICITY
Hour Min
2 56 Suddenly struck the side positively. and
then stood at 1/8 of an inch.
- 57 Closed
- 58 Very slowly opening negative. More clouds.
- 59 An inch wide negative.
3 0 Suddenly collapsed, and then struck the
sides negatively.
- 2 Strikes slowly negative.
- 3 Suddenly positive, then closed and open'd negative.
- 4 Closed suddenly, and then again open'd negative.
- 5 Suddenly changed to positive, and then
closed and open'd negative.
- 6 Suddenly changed to positive, and then
striking negatively.
- 7 Distant thunder heard, and the changes
of electricity were so quick that they
could not be distinctly noted.
- 15 A flash of lightening.
- 17 Another flash, and change from negative
to positive, and at the same instant a
loud clap.
- 18 A flash, and instant change from negative
to positive.
- 19 Flash and instant change.
- 20 Flash and clap, sudden closing, but no
change to positive.
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NEW EXPERIMENTS
Hour Min
3 25 Sudden change to positive, which continued
some time, then gradually
changed to negative. Darker but no rain.
- 27 Sudden change to positive.
- 30 A very slow change from negative to positive.
Beginning to rain.
- 31 Striking quick positively.
- 32 Thunder heard. Closing, then sudden
opening pos. Rain ceased.
- 35 Flash. Sudden close without changing,
more rain. Negative.
- 37 Flash and sudden change to positive.
- 45 Heavy rain. Slowly opening positively.
- 46 Striking slowly positive. Raining fast.
- 50 Sudden change to negative, and thunder heard.
- 55 Standing negative, then suddenly striking
negative, and presently again stopping
without changing. Distant thunder.
Rain ceased.
4 0 Opening slowly negative with a waving
motion till it strikes.
- 10 Still waving negative. No rain. Sky
cover'd with cloud.
- 15 A little rain. Changing slowly to positive.
- 22 Rain ceased, still positive without a waving motion.
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ON ELECTRICITY
Hour Min
4 30 Changed slowly to negative, without any
perceptible change of weather.
- 35 Several changes without rain, except at
distance of two miles.
- 38 Another change to negative.
- 43 Small rain, still negative.
- 48 Slowly raining; striking negative; then
waving and starting.
- 50 Raining faster, still striking negatively.
- 52 Distant thunder, without changing the electricity.
- 54 Raining fast, still negative.
5 0 Still raining fast,and electricity negative.
- 1 Suddenly changed to positive. Rain abating.
- 2 Rain ceased, still positive.
- 4 Fair, and gold leaf striking positively.
Sky clearing.
- 10 Still clearer. Positive electricity decreasing.
OBSERVATION XLII
May 24th, 1788. Ten o'clock at night. Barometer
29.05. Hygrometer 6 dry. Very calm
and clear, with a very bright aurora borealis. The
atmospheric apparatus was carried into a field, and
the electrometer consisted of a needle and a spider's
thread, with a very small bit of gold leaf fasten'd
to one end and both the needle and spider's thread
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NEW EXPERIMENTS
were suspended by means of the peg to which the
slips of gold leaf were usually fastened. The same
apparatus was also elevated in its usual place, but
tho' the spider's thread open'd slowly and struck the
sides positively, yet no agitation or other motion
happened, by which the electricity of the aurora
borealis could be distinguished from the common
electricity of serene air.
OBSERVATION XLIII
May 25th, 1788. Eleven o'clock at night, quite
calm and clear, a little appearance of aurora borealis.
Barom. 29.06. Hygrometer 77/8. The spider's
thread strikes the side, but not so often as the evening
before.
OBSERVATION XLIV
July 4th, 1788. A large cloud cover'd the horizon,
and it continued raining about two hours,
during which time the funnel without its lantern
was elevated, and the gold leaf changed its electricity
ten times, beginning and ending positively.
OBSERVATION XLV
July 5th, 1788. Large dark clouds frequently
passed over; therefore about 2 o'clock in the afternoon
a kite was raised, with a soften'd brass wire in
the string about 200 yards long. When the kite
had been flying about an hour, a dark cloud appeared
at a great distance, and changed the electricity
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ON ELECTRICITY
from positive to negative, which increased till
the cloud came nearly over, and some large drops
of rain fell, and to secure the string from being wet
I endeavoured to tie it on the opposite side of a post
to which it was before fastened; but when my hand
came near the string I received so severe a shock
that my arm was deprived of sensation during a few
seconds, and I was obliged to let the string go,
first terrified at the supposed loss of my left arm,
and then gratefully rejoicing to feel the returning
sensibility after rubbing with the other hand. The
explosion was heard at the distance of about 40 yards
like the loud crack of a whip. The kite was raised
often before and since this time, but without any
remarkable appearance.
OBSERVATION XLVI
July 30th, 1788. Ten o'clock at night.
Barometer 29.5. Hygrometer 46/8ths dry. The
sky clear and very calm. The aurora borealis very
bright. The apparatus with an electrometer made
of a spider's thread, was elevated, but no irregular
motion, or extraordinary quantity of electricity was
perceived.
OBSERVATION XLVII
August 16th, 1788. About 12 o'clock. Wind
S W. A large and well defined cloud passed over,
which as it approached open'd the gold leaf positively;
when about half over it changed and became
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NEW EXPERIMENTS
negative whilst very heavy drops of rain fell.
The gold leaf continued striking negatively to the
end of the shower, and then continued diminishing
about 20 minutes after the rain ceased.
OBSERVATION XLVIII
August 24th, 1788. Between 1 and 2 o'clock,
afternoon. Barometer 29.02. Thermometer 62°.
Hygrometer 6 dry. Two clouds passed over, but
not quite perpendicularly, and the electricity was
wholly negative, and continued negative during the
intervals; a third passed some what nearer and began
negatively, but ended positively; a fourth came
still nearer and blacker, which began and ended
wholly positive. No rain fell during the passage of
the last, and only a small quantity whilst the two
first were passing.
OBSERVATION XLIX
August 25th, 1788. Between 10 and 12 o'clock
in the morning. Barometer 29.02. Therm. 60.
Hygrometer 56/8 dry. Two clouds passed on
one side, which electrified the apparatus negatively;
a small quantity of rain fell, and more at a distance;
a third cloud came directly over, and then the gold
leaf open'd positively till it was about half over,
and then it became negative without rain.
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ON ELECTRICITY
OBSERVATION L
Jan.13th, 1789. Eleven o'clock in the morning.
Wind W. Barometer 28.8. Thermometer
on the north side of the house 26 degrees. Hygrometer
11/8 dry, having been frosty and the ground
cover'd with snow for several weeks. The wind
now strong and snowing fast. The gold leaf continued
slowly striking the sides positively. Another
observation was made during a shower of snow which
I omitted to note down, but found several changes
from positive to negative as in showers of rain.
FINIS
