I should be glad if you would send to my house for my sulphur globe, and the cushion belonging to it, and make the trial; but must caution you not to use chalk on the cushion, some fine powdered sulphur will do better. If, as I expect, you should find the globes to charge the prime conductor differently, I hope you will be able to discover some method of determining which it is that charges positively.-I am, &c. E. KINNERSLEY. B. Franklin to E. Kinnersley. Probable Course of the different Attractions and Repulsions of the two electrified Globes mentioned in the two preceding Letters. PHILADELPHIA, March 2, 1752. From these experiments one may be certain that your 2d, 3d, and 4th proposed experiments, would succeed exactly as you suppose, though I have not tried them, wanting time. I imagine it is the glass globe that charges positively, and the sulphur negatively, for these reasons: 1. Though the sulphur globe seems to work equally well with the glass one, yet it can never occasion so large and distant a spark between my knuckle and the conductor, when the sulphur one is working, as when the glass one is used; which, I suppose, is occasioned by this, that bodies of certain bigness cannot so easily part with a quantity of electrical fluid they have and hold attracted within their substance, as they can receive an additional quantity upon their surface by way of atmosphere. Therefore so much cannot be drawn out of the conductor, as can be thrown on it. 2. I observe that the stream or brush of fire, appearing at the end of a wire, connected with the conductor, is long, large, and much diverging, when the glass globe is used, and makes a snapping (or rattling) noise: but when the sulphur one is used, it is short, small, and makes a hissing noise; and just the reverse of both happens, when you hold the same wire in your hand, and the globes are worked alternately: the brush is large, long, diverging, and snapping (or rattling) when the sulphur globe is turned; short, small, and hissing, when the glass globe is turned.When the brush is long, large, and much diB. Franklin to E. Kinnersley. verging, the body to which it joins seems to Reasons for supposing, that the glass Globe me to be throwing the fire out; and when the charges positively, and the Sulphur negatively. contrary appears, it seems to be drinking in. -Hint respecting a leather Globe for Experi-3. I observe, that when I hold my knuckle bements when travelling. I THANK YOU for the experiments communicated. I sent immediately for your brimstone globe, in order to make the trials you desired, but found it wanted centres, which I have not time now to supply; but the first leisure I will get it fitted for use, try the experiments, and acquaint you with the result. In the mean time I suspect, that the different attractions and repulsions you observed, proceeded rather from the greater or smaller quantities of the fire you obtained from different bodies, than from its being of a different kind, or having a different direction. In haste, B. FRANKLIN. PHILADELPHIA, March 16, 1752. SIR,-Having brought your brimstone globe to work, I tried one of the experiments you proposed, and was agreeably surprised to find, that the glass globe being at one end of the conductor, and the sulphur globe at the other end, both globes in motion, no spark could be obtained from the conductor, unless when one globe turned slower or was not in so good order as the other; and then the spark was only in proportion to the difference, so that turning equally, or turning that slowest which worked best, would again bring the conductor to afford no spark. I found also, that the wire of a phial charged by the glass globe, attracted a cork ball that had touched the wire of a phial charged by the brimstone globe, and vice versa, so that the cork continued to play between the two phials, just as when one phial was charged through the wire, the other through the coating, by the glass globe alone. And two phials charged, the one by the brimstone globe, the other by the glass globe, would be both discharged by bringing their wires together, and shock the person holding the phials. fore the sulphur globe, while turning, the stream of fire between my knuckle and the globe seems to spread on its surface, as if it flowed from the finger; on the glass globe it is otherwise. 4. The cool wind (or what was called so) that we used to feel as coming from an electrified point, is, I think, more sensible when the glass globe is used, than when the sulphur one. But these are hasty thoughts. As to your fifth paradox, it must likewise be true, if the globes are alternately worked; but if worked together, the fire will neither come up nor go down by the chain, because one globe will drink it as fast as the other produces it. I should be glad to know, whether the effects would be contrary if the glass globe is solid, and the sulphur globe is hollow; but I have no means at present of trying. In your journeys, your glass globes meet with accidents, and sulphur ones are heavy and inconvenient.-Query. Would not a thin plane of brimstone, cast on a board, serve on occasion as a cushion, while a globe of leather stuffed (properly mounted) might receive the fire from the sulphur, and charge the conductor positively! Such a globe would be in no danger of breaking* I think I can con- The early LETTERS of Dr. Franklin on electricity having been translated into French, and printed at Paris; the Abbe Mazeas, in a letter to Dr. Stephen Hales, dated St. Germain, May 20, 1752, gives the following Account (printed in the Philosophical Transactions) of the Experiment made at Marly, in pursuance of that proposed by Dr. Franklin. mingled with a little hail, fell from the cloud, without either thunder or lightning; this cloud being, according to all appearance, only the consequence of a storm, which happened elsewhere.-I am, with a profound respect, your most humble and obedient servant, G. MAZEAS. A more particular Account of the Circum stances and Success of this extraordinary Experiment was laid before the Royal Academy of Sciences at Paris, three days afterwards, in a Memorial by M. d'Alibard, viz. Extrait d'un Memoire de M. D'Alibard. Lu a l'Academie Royale des Sciences, le 13 Mai, 1752. "EN suivant la route que M. Franklin nous a tracée, j'ai obtenu une satisfaction complette. Voici les préparatifs, le procédé et le succès. THE Philadelphian experiments, that Mr. Collinson, a member of the Royal Society, was so kind as to communicate to the public, having been universally admired in France, the king desired to see them performed. Wherefore the duke d'Ayen offered his majesty his country-house at St. Germain, where M. de Lor, professor of experimental philoso-six lieues de Paris au milieu d'une belle "1. J'ai fait faire à Marly-la-ville, située à phy, should put those of Philadelphia in exeplaine dont le sol est fort élevé, une verge de fer ronde, d'environ un pouce de diametre, longue de 40 pieds, et fort pointue par son extrémité supérieure; pour lui ménager une pointe plus fine, je l'ai fait armer d'acier trempé et ensuite brunir, au défaut de dorure, pour la préserver de la rouille; outre cela, cution. His majesty saw them with great satisfaction, and greatly applauded Messieurs Franklin and Collinson. These applauses of his majesty having excited in Messieurs de Buffon, d'Alibard, and de Lor, a desire of verifying the conjectures of Mr. Franklin, upon the analogy of thunder and electricity, they prepared themselves for making the experiment. M. d'Alibard chose for this purpose a garden situated at Marly, where he placed upon an electrical body a pointed bar of iron, of forty feet high. On the 10th of May, twenty minutes past two in the afternoon, a stormy cloud having passed over the place where the bar stood, those that were appointed to observe it, drew near, and attracted from it sparks of fire, perceiving the same kind of commotions as in the common electrical expe riments. M. de Lor, sensible of the good success of this experiment, resolved to repeat it at his house in the Estrapade, at Paris. He raised a bar of iron ninety-nine feet high, placed upon a cake of rosin, two feet square, and three inches thick. On the 18th of May, between four and five in the afternoon, a stormy cloud having passed over the bar, where it remained half an hour, he drew sparks from the bar, like those from the gun barrel, when in the electrical experiments, the globe is only rubbed by the cushion, and they produced the same noise, the same fire, and the same crackling. They drew the strongest sparks at the distance of nine lines, while the rain, The discoveries of the late ingenious Mr. Symmer, on the positive and negative electricity produced by the mutual friction of white and black silk, &c. afford hints for further improvements to be made with this VOL. II....2 M cette verge "2. J'ai fait planter dans un jardin trois grosses perches de 28 à 29 pieds, disposées en triangle, et éloignées les unes des autres d'environ huit pieds; deux de ces perches sont contre un mur, et la troisieme est au-desemble, l'on à cloué sur chacune des entredans du jardin. Pour les affermir toutes entoises à vingt pieds de hauteur; et comme le grand vent agitoit encore cette espéce dé'difice, l'on a attaché au haut de chaque perche de longs cordages, qui tenant lieu d'aubans, répondent par le bas à de bons piquets fortement enfoncés en terre à plus de 20 pieds des perches. "3. J'ai fait construire entre les deux perches voisines du mur, et adosser contre ce mur une petite guérite de bois capable de contenir un homme et une table. "4. J'ait fait placer au milieu de la guérite hauteur: et sur cette table j'ai fait dresser et une petite table d'environ un demi-pied de affermir un tabouret electrique. Ce tabouret n'est autre chose qu'une petite planche quarrée, portée sur trois bouteilles à vin; il n'est fait de cette matiere que pour suppléer au defaut d'un gâteau de résine qui me manquoit. "5. Tout étant ainsi préparé, j'ai fait elever | nuée d'orage et de grêle ne fut pas plus d'un perpendiculairement la verge de fer au milieu quart-d'heure à passer au zénith de notre ma des trois perches, et je l'ai affermie en l'attach-chine, et l'on n'entendit que ce seul coup de ant à chacune des perches avec de forts cor- tonnerre. Sitôt que le nuage fut passé, et dons de soie par deux endroits seulement. qu'on ne tira plus d'étincelles de la verge de Les premiers liens sont au haut des perches, fer, M. le Prieur de Marly fit partir le sieur environ trois pouces au-dessous de leurs ex- Coiffier lui-même, pour m'apporter la lettre trémités, supérieures; les seconds vers la suivante, qu'il m'écrivit à la hâte. moitié de leur hauteur. Le bout inférieur de la verge de fer est solidement appuyé sur le milieu du tabouret electrique, où j'ai fait creuser un trou propre à le recevoir. "6. Comme il étoit important de garantir de la pluie le tabouret et les cordons de soie, parce qu'ils laisseroient passer la matiéré électrique s'ils étoient mouillés, j'ai pris les précautions nécessaires pour en empécher. C'est dans cette vue que j'ai mis mon tabouret sous la guérite, et que j'avois fait courber ma verge de fer à angles aigus; afin que l'eau qui pourroit couler le long de cette verge, ne pût arriver jusques sur le tabouret. C'est aussi dans le même dessein que j'ai fait clouer sur le haut et au milieu de mes perches, à trois pouces au-dessus des cordons de soie, des especes de boîtes formées de trois petites planches d'environ 15 pouces de long, qui couvrent par-dessus et par les côtês une pareille longueur des cordons de soie, sans les toucher. "Il s'agissoit de faire, dans le tems de l'orage, deux observations sur cette verge de fer ainsi disposée; l'une étoit de remarquer á sa pointe une aigrette lumineuse, semblable à celle que l'on apperçoit à la pointe d'une aiguille, quand on l'oppose assez prés d'un corps actuellement électrisé; l'autre étoit de tirer de la verge de fer des étincelles, comme on en tire du canon de fusil dans les expériences électriques; et afin de se garantir des piquûres de ces étincelles, j'avois attaché le tenon d'un fil d'archal au cordon d'une longue fiole pour lui server de manche.... "Le Mécredi 10 Mai, 1752, entre deux et trois heures après midi, le nommé Coiffier, ancien dragon, que j'avois chargé de faire les observations en mon absence, ayant entendu un coup de tonnerre assez fort, vole aussitôt à la machine, prend la fiole avec le fil d'archal, présente le tenon du fil à la verge, en voit sortir une petite étincelle brilliante, et en entend le pétillement; il tire une seconde étincelle plus forte que la premiere et avec plus de bruit! il appelle ses voisins, et envoie chercher M. le Prieur. Celuici accourt de toutes ses forces; les paroissiens voyant la précipitation de leur curé, s'imaginent que le pauvre Coiffier a éte tué du tonnerre; l'allarme se répand dans le village; la grêle qui survient n'empêche point le troupeau de suivre son pasteur. Cet honnête ecclésiastique arrive près de la machine, et voyant qu'il n'y avoit point de danger, met luimême la main & l'œuvere et tire de fortes étincelles. Je vous annonce, Monsieur, ce que vous attendez: l'expérience est complette. Au|jourd'hui à deux heures 20 minutes après midi, le tonnerre a grondé directement sur Marly; le coup a été assez fort. L'envie de vous obliger, et la curiosité m'ont tiré de mon fauteuil, où j'étois occupé à lire : je suis allé chez Coiffier, qui déja m'avoit dépêché un enfant que j'ai rencontré en chemin, pour me prier de venir; j'ai doublé le pas à travers un torrent de grêle. Arrivé à l'endroit où est placée la tringle coudée, j'ai présenté le fil d'archal, en avançant successivement vers la tringle, à un pouce et demi, ou environ; il est sorti de la tringle une petite colonne de fer bleuâtre sentant le soufre, qui venoit frapper avec une extrême vivacité le tenon du fil d'archal, et occasionnoit un bruit semblable à celui qu'on feroit en frappant sur la tringle avec une clef. J'ai répété l'expérience au moins six fois dans l'espace d'envi ron quatre minutes, en présence de plusieurs personnes, et chaque expérience que j'ai faite a dure l'espace d'un pater et d'un ave. J'ai voulu continuer; l'action du feu s'est ralentie peu à peu ; j'ai approché plus près, et n'ai plus tiré que quelques étincellss, et enfin rien n'a paru. Le coup de tonnerre qui a occasionné cet évenément, n'a été suivi d'aucun autre; tout s'est terminé par une abondance de gréle. J'étois si occupé dans le moment de l'expérience de ce que voyois, qu'ayant été frappé au bras un peu au-dessus du coude, je ne puis dire si c'est en touchant au fil d'archal ou à la tringle: je ne me suis pas plaint du mal que m'avoit fait le coup dans le moment que je l'ai reçu; mais comme la douleur continuoit, de retour chez moi, j'ai découvert mon bras en présence de Coiffier, et nous avons apperçu une meurtrissure tournante autour du bras, samblable à celle que feroit un coup de fil d'archal, si j'en avois été frappé à nud. En revenant de chez Coiffier, j'ai recontré M. le Vicaire, M. de Milly, et le maitre d'école, à qui j'ai rapporté ce qui venoit d'arriver; ils se sont plaints tous les trois qu'ils sentoient une odeur de soufre qui les frappoit _davantage à mesure qu'ils s'approchoient de moi: j'ai porté chez moi la même odeur, et mes domestiques s'en sont apperçus sans que je leur aye rien dit. Voilà Monsieur, un récit fait à la héte, mais naif et vrai j'atteste, et vous pouvez asLasurer que je suis prêt à rendre témoignage de cet événement dans toutes les occasions. | by wetting the apparatus, the electricity was Coiffier a été le premier qui a fait l'expéri- dissipated too soon to be perceived upon ence et l'a répétée plusieurs fois; ce n'est qu'à l'occasion de ce qu'il a vu qu'il m'a envoyé prier de venir. S'il étoit besoin d'autres temoins que de lui et de moi, vous les trouveriez. Coiffier presse pour partir. Je suis avec une respectueuse consideration, Monsieur, votre, et. signè RAULET, Prieur de Marly. 10 Mai, 1752. "On voit, par le détail de cette lettre, que le fait est assez bien constaté pour ne laisser aucun doute à ce sujet. Le porteur m'a assuré de vive voix qu'il avoit tiré pendant près d'un quart-d'heure avant que M. le Prieur arrivât, en présence de cinq ou six personnes, des étincelles plus fortes et plus bruyantes que celles dont il est parlé dans la lettre. Čes premieres personnes arrivant successivement, n'osient approcher qu'à 10 ou 12 pas de la machine; et à cette distance, malgré le plein soleil, ils voyoient les étincelles et entendoient le bruit..... ...... "Il résulte de toutes les expériences et observations que j'ai rapportées dans ce mémoire, et surtout de la derniere expérience faite à Marly-la-ville, que la matière du tonnerre est incontestablement la même que celle de l'électricité. L'idée qu'en a eue M. Franklin cesse d'être une conjecture: la voilà devenue une réalité, et j'ose croire que plus on approfondira tout ce qu'il a publié sur l'électricité, plus on reconnoîtra combien la physique lui est redevable pour cette partie." Letter of Mr. W. Watson, F. R. S. to the Royal Society, concerning the Electrical Experiments in England upon ThunderClouds.-Read Dec. 1752. Trans. Vol. xlvii. AFTER the communications, which we have received from several of our correspondents in different parts of the continent, acquainting us with the success of their experiments last summer, in endeavouring to extract the electricity from the atmosphere during a thunderstorm, in consequence of Mr. Franklin's hypothesis, it may be thought extraordinary, that no accounts have been yet laid before you of our success here from the same experiments. That no want of attention, therefore, may be attributed to those here, who have been hitherto conversant in these inquiries, I thought proper to apprize you, that, though several members of the Royal Society, as well as myself, did, upon the first advices from France, prepare and set up the necessary apparatus for this purpose, we were defeated in our expectations, from the uncommon coolness and dampness of the air here, during the whole summer. We had only at London one thunder-storm; viz. on July 20; and then the thunder was accompanied with rain; so that, touching those parts of the apparatus, which served to conduct it. This, I say, in general prevented our verifying Mr. Franklin's hypothesis: but our worthy brother, Mr. Canton, was more fortunate, I take the liberty, therefore, of laying before you an extract of a letter, which I received from that gentleman, dated from Spital-square, July 21, 1752. "I had yesterday, about five in the afternoon, an opportunity of trying Mr. Franklin's experiment of extracting the electrical fire from the clouds; and succeeded, by means of a tin tube, between three and four feet in length, fixed to the top of a glass, one of about eighteen inches. To the upper end of the tin tube, which was not so high as a stack of chimnies on the same house, I fastened three needles with some wire; and to the lower end was soldered a tin cover, to keep the rain from the glass tube, which was set upright in a block of wood. I attended this apparatus as soon after the thunder began as possible, but did not find it in the least electrified, till between the third and fourth clap; when applying my knuckle to the edge of the cover, I felt and heard an electrical spark; and approaching it a second time, I received the spark at the distance of about half an inch, and saw it distinctly. This I repeated four or five times in the space of a minute, but the sparks grew weaker and weaker; and in less than two minutes the tin tube did not appear to be electrified at all. The rain continued during the thunder, but was considerably abated at the time of making the experiment." Thus far Mr. Canton. Mr. Wilson likewise of the Society, to whom we are much obliged for the trouble he has taken in these pursuits, had an opportunity of verifying Mr. Franklin's hypothesis. He informed me, by a letter from near Chelmsford, in Essex, dated August 12, 1752, that, on that day about noon, he perceived several electrical snaps, during, or rather at the end of a thunder-storm, from no other apparatus than an iron curtain rod, one end of which he put into the neck of a glass phial, and held this phial in his hand. To the other end of the iron he fastened three needles with some silk. This phial, supporting the rod, he held in one hand, and drew snap from the rod with a finger of his other. This experiment was not made upon any eminence, but in the garden of a gentleman, at whose house he then was. Dr. Bevis observed, at Mr. Cave's, at St. John's Gate, nearly the same phenomena as Mr. Canton, of which an account has been already laid before the public. Trifling as the effects here mentioned are, when compared with those which we have received from Paris and Berlin, they are the only ones, that the last summer here has produced; and as they were made by persons worthy of credit, they tend to establish the authenticity of those transmitted from our correspondents. I flatter myself, that this short account of these matters will not be disagreeable to you; and am, W. WATSON.* Remarks on the Abbé Nollet's Letters to Benjamin Franklin, of Philadelphia, on elec-out by sparks, a vast number of them may tricity: by David Colden, of New York. COLDENHAM, in New York, Dec. 4, 1753. ger to it, a spark will issue from it to your finger: now when a phial, prepared for the Leyden experiment, is hung to the gun-barrel or prime conductor, and you turn the globe in order to charge it; as soon as the electric matter is excited, you can observe a spark to issue from the external surface of the phial to your finger, which, Mr. Franklin says, is the natural electric matter of the glass driven out by that received by the inner surface from the conductor. If it be only drawn be drawn; but if you take hold of the external surface with your hand, the phial will soon receive all the electric matter it is capaIN considering the Abbé Nollet's Letters ble of, and the outside will then be entirely to Mr. Franklin, I am obliged to pass by all destitute of its electric matter, and no spark the experiments which are made with, or in, can be drawn from it by the finger: here then bottles hermetically sealed, or exhausted of is a want of that effect, which all bodies chargair; because, not being able to repeat the ex-ed with electricity have. Some of the effects periments, I could not second any thing which of an electric body, which I suppose the Abbe occurs to me thereon, by experimental proof. has observed in the exterior surface of a Wherefore, the first point wherein I can dare charged phial, are, that all light bodies are atto give my opinion, is in the Abbé's 4th tracted by it. This is an effect which I have letter, where he undertakes to prove, that constantly observed, but do not think that it the electric matter passes from one surface to proceeds from an attractive quality in the exanother through the entire thickness of the terior surface of the phial, but in those light glass: he takes Mr. Franklin's experiment of bodies themselves, which seem to be attractthe magical picture, and writes thus of it: ed by the phial. It is a constant observation, "When you electrise a pane of glass coated that when one body has a greater charge of on both sides with metal, it is evident that electric matter in it than another (that is in whatever is placed on the side opposite to proportion to the quantity they will hold) this that which receives the electricity from the body will attract that which has less: now, I conductor, receives also an evident electrical suppose, and it is a part of Mr. Franklin's virtue." Which Mr. Franklin says, is that system, that all those light bodies which apequal quantity of electric matter, driven out pear to be attracted, have more electric matof this side, by what is received from the con- ter in them than the external surface of the ductor on the other side; and which will con- phial has, wherefore they endeavour to attinue to give an electrical virtue to any thing tract the phial to them, which is too heavy to in contact with it, till it is entirely discharg- be moved by the small degree of force they ed of its electrical fire. To which the Abbé exert, and yet being greater than their own thus objects: "Tell me (says he,) I pray you, weight, moves them to the phial. The folhow much time is necessary for this pretend-lowing experiment will help the imagination ed discharge? I can assure you, that after in conceiving this. Suspend a cork ball, or having maintained the electrisation for hours, a feather, by a silk thread, and electrise it; this surface, which ought, as it seems to me, to be entirely discharged of its electrical matter, considering either the vast number of sparks that were drawn from it, or the time that this matter had been exposed to the action of the expulsive cause; this surface, I say, appeared rather better electrised thereby, and more proper to produce all the effects of an actual electric body." The Abbe does not tell us what those effects were, all the effects I could never observe, and those that are to be observed can easily be accounted for, by supposing that side to be entirely destitute of electric matter. The most sensible effect of a body charged with electricity is, that when you present your fin *This is the sometime celebrated Watson, bishop of LandaffTM then bring this ball nigh to any fixed body, and it will appear to be attracted by that body, for it will fly to it: now, by the consent of electricians, the attractive cause is in the ball itself, and not in the fixed body to which it flies: this is a similar case with the apparent attraction of light bodies, to the external surface of a charged phial. The Abbé says, "that he can electrise a hundred men, standing on wax, if they hold hands, and if one of them touch one of these surfaces (the exterior) with the end of his finger:" this I know he can, while the phial is charging, but after the phial is charged I am as certain he cannot: that is, hang a phial, prepared for the Leyden experiment, to the conductor, and let a man, standing on the floor, touch the coating with his finger, while the globe is turned, till the electric matter |