Updated 27 Jan 2005

WIRKSWORTH Parish Records 1600-1900

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New Experiments on Electricity


Abraham Bennet 1789

    In 1789 Abraham BENNET, who was Curate of Wirksworth, published a book called "New Experiments on Electricity". Bennet, soon to become a Fellow of the Royal Society, had an impressive list of 408 subscribers who backed the printing of his book, which was important in the early understanding of the Theory of Electricity. There seemed to be no transcription of the book on the Internet, and as I had inherited a copy of this rare book from my grandfather I decided to produce a transcription and put it on my website. Enquiries to
    Transcriber's note: spelling or punctuation not understood is marked: [?]. Links have been inserted to ease reading on the Internet. Transcribed at Eadar Dha Fhadhail (Ardroil), Isle of Lewis in the Outer Hebrides, Scotland, January 2005]

Transcribed at

Ardroil Jan 05
Outer Hebrides

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PAGE: v, x, xv, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140: PAGE



    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


    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


    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


    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,


    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


    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


    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


    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.


    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


    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


    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


    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.


    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


    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.


    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.


    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.


    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.



    June 8th, 1787. The sky was entirely overcast and small rain fell for several hours, which electrified the apparatus positively.


    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.


    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.


    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.


    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.


    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.


    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.


    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.



    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.


    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.


    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.


    August 4th, 1787, Ten o'clock in the morning. Wind W. Barometer 29.15. Sky very clear. The gold leaf opened just sensibly positive.



    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.


    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.



    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.


    August 16th, 1787. Nine o'clock in the morning. Wind quite calm. A thick mist. Electrometer open'd half an inch positively.


    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.


    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.


    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.


    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.


    August 27th, 1787. Two o'clock in the afternoon. Wind N. Barometer 29.3. A shower


    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.


    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.


    Dec. 25th, 1787 Wind E. Small snow falling all day. Gold leaf diverged strongly positive, tried several times.


    Dec. 27th, 1787. Wind N E. Snow melting. A few white clouds. Electricity strongly positive.


    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.



    Jan. 2d, 1788. Wind S. Small rain. Electricity negative.

    Jan. 6th, 1788. Wind S. Small rain. Electricity negative.


    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.


    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.


    Feb.19th, 1788. Wind S W and gentle snow continued falling for several hours. The electrometer diverged about an inch positively.



    Feb.20th, 1788. Wind E. No frost but a very thick mist. Gold leaf struck the sides positively.


    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.


    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.


    March 18th, 1788. Wind N E. brisk. Overcast but fair. Electricity insensible with the candle, never observed so weak before.


    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.



    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.


    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.


    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.


    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.


    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.


    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


    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.


    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.


    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.


    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.


    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.



    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.


    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.


    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.


    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.


    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.


    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


    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.


    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.


    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.


    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


    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.


    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.


    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


    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.


    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.


    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.



    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.



[Electrical pattern made with an electrophorus,
and formed from powdered resin]

Plate III (pp 52-53)
[The deal-rod apparatus for detecting atmospheric electricity,
a device for diffusing powders to reveal their charges, and
other of Bennet's apparatus described in the New Experiments]

Plate I (pp 76-77)
[Bennet's gold-leaf electroscope and simple doubler]

Plate II (pp 82-83)
[Nicholson's revolving doubler]


    Rara corpora illa sint, inter quorum partes multa intervalla existunt, corporibus aliis repleta. Ut cum videmus spongiam aqua vel alio liquore turgentem. Etsi cum aer aut aqua sit rarefacta, non videamus ullos ipsorum poros qui ampliores reddantur, nec ullum novum corpus, quod ad illos replendos accedat; non est tamen rationi tam consentaneum, aliquid non intelligibile effingere, ad eorum rarefactionem verbotenus explicandam, quam ex hoc quod rarefiant, concludere, in ipsis esse poros, sive intervalla quae ampliora redduntur, & novum aliquod corpus accedere, quod ipsa implet; etsihoc novum corpus nullo sensu percipiamus. Nulla enim ratio nos cogit ad credendum, corpora omnia quae existunt debere sensus nostros afficere.
    Des Cartes Prin. Philos.
    Par.2. Sect.6.

    Translation from The Classical Library, see section 6:

    "But with regard to rarefaction and condensation, whoever gives his attention to his own thoughts, and admits nothing of which he is not clearly conscious, will not suppose that there is anything in those processes further than a change of figure in the body rarefied or condensed: so that, in other words, rare bodies are those between the parts of which there are numerous distances filled with other bodies; and dense bodies, on the other hand, those whose parts approaching each other, either diminish these distances or take them wholly away, in the latter of which cases the body is rendered absolutely dense. The body, however, when condensed, has not, therefore, less extension than when the parts embrace a greater space, owing to their removal from each other, and their dispersion into branches. For we ought not to attribute to it the extension of the pores or distances which its parts do not occupy when it is rarefied, but to the other bodies that fill these interstices; just as when we see a sponge full of water or any other liquid, we do not suppose that each part of the sponge has on this account greater extension than when compressed and dry, but only that its pores are wider, and therefore that the body is diffused over a larger space."

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Transcribed, compiled, formatted, hyperlinked, encoded, and copyright © 2005, John Palmer,
All Rights Reserved.