Chapter XX: Book I: chap. i. Therein, he says that Baptista Porta, who has made the (5)

=A.D. 1750.=--Wargentin (Pierre Guillaume--Perh Vilhelm--) (1717–1783), Secretary to the Swedish Academy of Sciences and a distinguished astronomer, addresses, on the 21st of February, a letter to the Royal Society, of which a copy is to be found in Vol. XLVII. p. 126 of the _Phil. Trans._ In this he gives his observations of the result produced on the magnetic needle by the aurora borealis.

We have already seen (under the A.D. 1683 date), that the discovery of the fact that magnets are affected by the polar lights has been ascribed to Wargentin, and we have also learned (A.D. 1722) that he ascertained the diurnal changes of the magnetic needle with more precision than had been done by George Graham.

REFERENCES.--Walker, “Magnetism,” p. 116; _American Journal
Science and Arts_, 1841, Vol. XXX. p. 227; Celsius, A.D. 1740,
and the abridgments of Hutton, Vol. X. p. 165.

=A.D. 1750.=--Michell (John), an eminent English man of science, Professor at Queens’ College, Cambridge, publishes “A treatise of Artificial Magnets, in which is shown an easy and expeditious method of making them superior to the best natural ones.”

The process introduced by this work is known as that of the “double touch.” This consists in first joining, at about a quarter of an inch distance, two bundles of strongly magnetized bars, having their opposite poles together, and in drawing these bars backward and forward upon and along the entire length of the bars to be magnetized, which latter have already been laid down end to end and in a straight line. The operation is to be repeated upon each side of the bars. The central bars of a series thus acquire at first a higher degree of magnetism than do the outer ones, but by transposing the latter and treating all alike the magnetic virtue is evenly distributed. In this process the external bars act the same part as do the pieces of soft iron employed in the Duhamel method.

At Chap. VI. p. 20 of the third volume of his “Rudimentary Magnetism,” Harris thus expresses himself: “Michell advanced the idea that in all the experiments of Hauksbee, Dr. Brooke Taylor, William Whiston and Musschenbroek, the force may really be in the inverse duplicate ratio of the distances, proper allowance being made for the disturbing changes in the magnetic forces so inseparable from the nature of the experiment. He is hence led to conclude that the true law of the force is identical with that of gravity, although he does not set it down as certain.”

REFERENCES.--Harris, “Rud. Mag.,” I. and II. pp. 94–95; C. R.
Weld, “Hist. Roy. Soc.,” Vol. I. p. 512; _Phil. Trans._, Vol.
LI. pp. 390, 393, and Hutton’s abridgment, Vol. XI. p. 418;
Gaugain’s observations in “Sc. Am. Suppl.,” No. 7, p. 99.

=A.D. 1750.=--Boulanger--not Boullangère--(Nicholas Antoine) (1722–1759), a well-known French writer, whose extensive studies were interrupted by his death, in 1759, at the early age of thirty-seven, gives, in this “Traité de la cause et des phénomènes de l’électricité,” accounts of many important observations made in the electrical field.

His attention was carefully given to ascertaining the degrees in which different substances are capable of being excited, and he gives several lists of such, inferring therefrom that the most transparent and the most brittle are always the most electric.

At pp. 64 and 124 of the above-named “Traité” he states that electricity affects mineral waters much more sensibly than common water; that black ribbons are more readily attracted than those of other colours, next to the black being the brown and deep red; and that, of two glass cylinders exactly alike, except that one is transparent and the other slightly coloured, the transparent one will be the more readily excited.

REFERENCES.--The “Traité,” notably at pp. 135 and 164; “Biog.
Générale,” Vol. VI. p. 939; Le Bas, “Dict. Encycl. de la
France”; Quérard, “La France Littéraire”; Chaudon et Delandine,
“Dict. historique.”

=A.D. 1751.=--Adanson (Michael), a French naturalist of very high reputation, who, before the age of nineteen, had actually described four thousand species of the three kingdoms of nature, introduces in his “History of Senegal” the _silurus electricus_, a large species of eel originally brought from Surinam. Sir John Leslie states that the _silurus_ is furnished with a very peculiar and complex nervous apparatus which has been fancifully likened to an electrical battery, and that, from a healthy specimen exhibited in London, vivid sparks were drawn in a darkened room. M. Broussonet alludes to the _silurus_ as _Le Trembleur_ in the “Hist. de l’Acad. Royale des Sciences” for 1782, p. 692.

Adanson also called attention, in 1756, to the electrical powers of the _malapterus electricus_, but, according to the able naturalist, James Wilson (“Ichthyology,” _Encycl. Brit._), there is a much earlier account of the fish extracted from the narrative of Baretus and Oviedo dated 1554.

The Swedish scientist, Karl A. Rudolphi, pupil of Linnæus, called the _princeps helminthologorum_, has given a detailed description as well as illustrations of the electric organs of the _malapterus_ in “Ueber den Zitter-wels,” _Abh. Berl. Acad._ VII.... This fish, which the Arabs call _Raad_ or _Raash_ (thunder), gives its discharge chiefly when touched on the head, but is powerless when held by the tail, the electrical organs in fact not reaching the caudal fin.

To Adanson has been attributed the authorship of an essay on the “Electricity of the Tourmaline” Paris, 1757, which bears the name of the Duke de Noya Caraffa.

REFERENCES.--Spreng, “Hist. R. Herb.,” Vol. II; and “Adanson’s
Biog.,” Vol. II. “Encycl. Britannica,” Rees’ “Cycl.” Supplement
and in “Bibl. Universelle,” Vol. I; Chambers’ “Encyl.” for 1868,
Vol. III. p. 822; Cavallo, “Nat. Phil.,” Philad., 1825, Vol. II.
p. 237; _Scientific American Supplement_, No. 457, pp. 7300,
7301; Rozier, Vol. XXVII. p. 139, and W. Bryant in _Trans. Am.
Phil. Soc._ II. p. 166, O. S.

=A.D. 1752.=--Franklin (Benjamin) (1706–1790), an able American editor, philosopher and statesman, crowns his many experiments with the brilliant discovery of the identity of electricity and lightning. Humboldt says: “From this period the electric process passes from the domain of speculative physics into that of cosmical contemplation--from the recesses of the study to the freedom of nature” (“Cosmos,” Vol. II. 1849, p. 727). Wall (A.D. 1708) had only alluded to the resemblance of electricity to thunder and lightning; Grey (A.D. 1720) had conjectured their identity and implied that they differed only in one degree, while Nollet (A.D. 1746) pointed out a closer relationship than ever before adduced between lightning and the electric spark; but it was left for Franklin to prove the fact with empirical certainty.

Franklin’s attention was first directed to electrical studies in 1745, by a letter from Peter Collinson, Fellow of the Royal Society of London, to the Literary Society of Philadelphia, and he first wrote on the subject to that gentleman on the 28th of July, 1747. This was followed by several other similar communications up to April 18, 1754, the whole of which comprise most of what subsequently appeared under the title “New Experiments and Observations on Electricity, made at Philadelphia, in America, by Benjamin Franklin, LL.D. and F.R.S.”

Franklin first entertained the idea that lightning was not likely to be attracted by a pointed rod unless the latter was placed at a great height, and he therefore waited for the erection of a tall spire in Philadelphia which he intended to utilize for his observations, but delay in its completion led him to use a kite pointed with an iron rod, not doubting that the electric fluid could, during a thunderstorm, be drawn from it through a string.

The manner of constructing and employing the kite, and the attending results, are thus given in a letter dated Oct. 19, 1752 (Letter XII, “Experiments and observations on Electricity”): “Make a small cross of two light strips of cedar, the arms so long as to reach to the four corners of a large thin silk handkerchief when extended. Tie the corners of the handkerchief to the extremities of the cross, so you have the body of a kite which, being properly accommodated with a tail, loop and string, will rise in the air like those made of paper; but, this being made of silk, is fitter to bear the wet and wind of a thunder-gust without tearing. To the top of the upright stick of the cross is to be fixed a very sharp-pointed wire, rising a foot or more above the wood. In the end of the twine, next the hand, is to be held a silk ribbon, and where the silk and twine join a key may be fastened. This kite is to be raised when a thunder-gust appears to be coming on, and the person who holds the string must stand within a door or window, or under some cover, so that the silk ribbon may not be wet, and care must be taken that the twine does not touch the frame of the door or window. As soon as any of the thunder clouds come over the kite, the pointed wire will draw the electric fire from them, and the kite with all the twine will be electrified, and the lose filaments of the twine will stand out every way and be attracted by an approaching finger. And when the rain has wetted the kite so that it can conduct the electric fire freely, you will find it stream out plentifully from the key on the approach of your knuckle. At this key, the phial (Leyden jar) may be charged, and from electric fire thus obtained spirits may be kindled, and all the other electric experiments be performed which are usually done by the help of a rubber glass globe or tube, and thereby the sameness of the electric matter with that of lightning completely demonstrated.”

It was during the month of June 1752, on the approach of a storm, that he and his son walked out upon the Philadelphia Commons and first raised the kite. At the outset no important results were obtained, but as soon as the cord became wet by the shower that followed, the electric sparks were easily drawn from the key and enabled Franklin to charge and give shocks from a Leyden jar.

Thus, says Sabine, was Benjamin Franklin successful in one of the boldest experiments ever made by man upon the powers of nature, and from that moment he became immortal.

He had already, in 1749, made public the following, which is embodied in one of his letters to Mr. Collinson: “The electrical spark is zigzag, and not straight; so is lightning. Pointed bodies attract electricity; lightning strikes mountains, trees, spires, masts and chimneys. When different paths are offered to the escape of electricity, it chooses the best conductor; so does lightning. Electricity fires combustibles; so does lightning. Electricity fuses metals; so does lightning. Lightning rends bad conductors when it strikes them; so does electricity when rendered sufficiently strong. Lightning reverses the poles of a magnet; electricity has the same effect.”

Franklin had, likewise, published at about the same period the plan for an experiment to ascertain from elevated structures whether the clouds that contain lightning are electrified or not. He himself had proposed to put the plan to execution; but he was led to try the kite experiment, and, meanwhile, his suggestions had been successfully acted upon, in France, by M. Dalibard and de Lor, as will be shown later on.

“The lightning, which doth cease to be, ere one can say, ‘it
lightens.’”--Shakespeare.

“First let me talk with this philosopher; what is the cause of
thunder?”--Shakespeare.

“... a way for the lightning of the thunder.”--Job xxviii. 26,
and xxxviii. 25.

“It related not to the instances of the _magneticalness_ of
lightning.”--“Hist. of Roy. Soc.,” by Thomas Birch, Vol. IV. p.
253.

When specifying the great points of coincidence existing between the ordinary electric discharge and lightning, Franklin, as already partly stated, had remarked that flashes of lightning are frequently waving and crooked, of a zigzag or forked appearance, sometimes diffused and sometimes coloured (“On the Nature of Thunderstorms,” W. Snow Harris, London, 1843, p. 24; Priestley, “History and Present State of Electricity,” London, 1769, p. 166; “Encycl. Metropol.,” article “Electricity”; Biot, “Traité de Physique,” Vol. II). In treating of the subject of lightning flashes, Dr. L. D. Gale (trans. of M. F. J. F. Duprez’s paper on “Atmospheric Electricity,” taken from the memoirs of the Royal Academy of Brussels) alludes to the attempts made by C. G. Helvig to determine the velocity of the linear flashes (Gilbert’s _Annalen_, Vol. LI. pp. 136 and 139, ss. 2, 10) which he estimated to be 40,000 to 50,000 feet in a second, and states that M. Weigsenborn, of Weimar (_Comptes Rendus_, Vol. IX. p. 218), calculated the velocity of a flash observed in 1839 to be more than two leagues, while M. François Arago (“Annuaire,” etc., pour l’année 1838, pp. 249, 255, 257, 459, estimated the lengths of certain flashes to be 3·3, 3·6, 3·8 leagues. The views of Messrs. Logan (_Phil. Trans._, 1735, Vol. XXXIX. p. 240), L. J. Gay-Lussac (_Ann. de Chim. et de Phys._, 1805, Vol. XXIX. p. 105), H. W. Brandes (“Beiträge zur Witterungskunde,” etc., 1820, p. 353), C. H. Pfaff and L. E. Kaemtz (J. S. T. Gehler, “Dict. de Phys.,” Vol. I. p. 1001, and “Lehrbuch d. Meteor,” Vol. II. p. 430), Gabriel Lamé (“Cours. de Phys. de l’Ecole Polytech.,” Tome II. 2^e partie, p. 82), Becquerel (_Comptes Rendus_, 1839, Tome VIII. p. 216), Faraday (_Philos. Magazine_, 1841, Vol. XIX. p. 104), Pouillet (“Eléments de Phys. et de Météor,” Tome II. p. 808), Parrot (J. S. T. Gehler, “Dict. de Phys.,” Vol. I. p. 999), are also set forth in the above-named translation of M. Duprez’s valuable work.

Humboldt informs us that “the most important ancient notice of the relations between lightning and conducting metals is that of Ctesias, in his _Indica_, Cap. IV. p. 169. He possessed two iron swords, presents from the King Artaxerxes Mnemon, and from his mother Parysatis, which, when planted in the earth, averted clouds, hail and _strokes of lightning_. He had himself seen the operation, for the king had twice made the experiment before his eyes” (“Cosmos,” Vol. II. N. 186). Ctesias was a man of great learning. He was a contemporary of Xenophon, and lived for a number of years at the Court of Artaxerxes Mnemon as private physician to the king. Diodorus states that Ctesias was highly honoured at the Persian court. An abridged edition of the _Indica_ was printed by Stephens in 1594 (“Hist. Roy. Soc.,” C. R. Weld, London, 1848, Vol. II. p. 93; “La Grande Encyclopédie,” Vol. XIII. p. 536; “Biographie Générale,” Vol. XII. p. 568).

In imitation of Franklin, Doctor Lining, of Charleston, in South Carolina, sent a kite into a thunder cloud, and by that means dissipated the lightning (_Philosophical Transactions_ for 1754, Vol. XLVIII. p. 757).

The opinion entertained by Franklin regarding the nature of electricity differs from that previously submitted by Dufay (A.D. 1733), in the manner shown by Noad at p. 6 of his Manual, London, 1859 edition.

What Dufay considered to be two distinct species of electricities, _vitreous_ and _resinous_, Franklin conceived to be two different states of the same electricity, which he called _positive_ and _negative_. This, which constitutes the foundation of the present theory of electricity, is usually called the Franklinian theory, but it can be said to belong equally to Dr. Watson, for he had communicated it to the Royal Society before Franklin’s opinion on the subject was known in England (_Phil. Trans._ for 1748, Vol. XLV. pp. 49, 491; Thomson, “Hist. Roy. Soc.,” p. 436). Noad, in paragraph 12, applies the latter theory to the case of a charged Leyden jar, alluding to Franklin’s discovery of the location of electricity in the jar, wherefrom is drawn the conclusion that it is upon the glass that the electricity is deposited, and that the conducting coatings serve “only, like the armature of the loadstone, to unite the forces of the several parts and bring them at once to any point desired” (see “Œuvres de Franklin,” trans. of Barbeu-Dubourg, Tome II. p. 16, 3^e lettre).

Of his _plus_ and _minus_ theory, Franklin thus wrote to Mr. Collinson: “To electrise _plus_ or _minus_ no more needs to be known than this, that the parts of the tube or sphere that are rubbed do, in the instant of the friction, attract the electrical fire, and therefore take it from the thing rubbing; the same parts, immediately as the friction upon them ceases, are disposed to give the fire they have received to any body that has less.”

In an appendix to his official report as U.S. Commissioner at the Paris Universal Exposition of 1867, entitled “Franklin and Electrical Semaphores,” Professor Samuel F. B. Morse, LL.D., expressed himself as follows:

“It has frequently been asserted (on what authority I know not) that the first idea of an electric semaphore originated with Franklin. I have sought in vain in the publication of Franklin’s experiments and works for anything confirmatory of this assertion. On mentioning the subject to my friend Professor Blake, he kindly proposed examining the writings of Franklin in order to elicit the truth. From him I have received the following:

“‘I consulted several works for the purpose of ascertaining, if possible, the foundation for the statement that Franklin suggested the idea of semaphores by static electricity. I have not yet found any such suggestion, but I have noted that, following the experiments by Dr. Watson and others, in England, to determine the _velocity_ of the electric discharge, and the time supposed to be required for the electrical discharges across the Thames, by which spirits were kindled, etc. (in 1747), Dr. Franklin (in 1748) made some similar experiments upon the banks of the Schuylkill, and amused his friends by sending a spark “from side to side through the river without any other conductor than the water” (vide Priestley’s “History of Electricity”). This was in 1748, at the end of the year. In 1756 “J. A., Esq.,” of New York (James Alexander), presented to the Royal Society a proposition “to measure the time taken by an electric spark in moving through any given space” by sending the discharge or spark down the Susquehanna or Potomac, and round by way of the Mississippi and Ohio rivers, so that the “electric fire” would have a circuit of some thousands of miles to go. All this was upon the supposition or assumption that the electric fire would choose a continuous water conductor rather than to return or pass through the earth. Franklin presented a paper in reply, in which he says “the proposed experiment (though well imagined and very ingenious) of sending the spark round through a vast length of space, etc. etc., would not afford the satisfaction desired, though we could be sure that the motion of the electric fluid would be in that tract, and not underground in the wet earth by the shortest way”’ (‘Franklin’s Experiments on Electricity, and Letters and Papers on Philosophical Subjects,’ 4to, London, MDCCLXIX, pp. 282, 283).

“Can it be possible that Franklin’s experiment of firing spirits and showing the spark and the effects of the electric discharge across the river originated, or forms the foundation for, the statement that he suggested the semaphoric use of electricity?”

After speaking of the experiments, to which allusion was made (at Watson, A.D. 1745), Franklin writes: “... It is proposed to put an end to them for this season, somewhat humorously, in a party of pleasure, on the banks of the Schuylkill. Spirits at the same time are to be fired by a spark sent from side to side through the river without any other conductor than the water--an experiment which we some time since performed to the amazement of many. A turkey is to be killed for our dinner by the electrical shock, and roasted by the electrical jack, before a fire kindled by the electrified bottle, when the healths of all the famous electricians in England, Holland, France and Germany are to be drank in electrified bumpers under the discharge of guns from the electrical battery.”

It was toward the close of the year 1750 that Franklin entertained the practicability of a lightning conductor (see Winckler, A.D. 1733), and, for this, he says, he was indebted to an experiment made by his friend Mr. Thomas Hopkinson (vide Franklin’s “Complete Works,” London, 1806, Vol. I. p. 172). In his “Poor Richard’s Almanac” for 1753, he refers to the lightning rod as security for “habitations and other buildings from mischief by thunder and lightning.”

REFERENCES.--J. B. Le Roy, “Lettera al Rozier,” etc., Milano,
1782; “Rec. de Mém. de l’Acad. des Sc.” for 1770 and 1773;
_Jour. de Phys._, 1773, Vol. II; Memoirs of M. Beyer, Paris,
1806–1809, and Delaunay’s explanation of his theories at pp.
193–198 of his 1809 Manuel.

The many notable observations, experiments and discoveries of Franklin are nowhere more ably reviewed than by his great admirer Dr. Priestley, who devotes much space thereto in his justly celebrated work on electricity.

At p. 92 of his “New Experiments,” etc., London, 1774, Franklin alludes to the failure of many European electricians in firing gunpowder by the electric spark, and gives his own method by using a battery of four large glass jars, while at p. 423 of the London edition of his “Letters and Papers,” etc., Franklin relates curious observations which are worth mentioning here. He says that he sent a charge of electricity “through a small glass tube that had borne it well when empty, but when filled with water was shattered to pieces and driven all about the room. Finding no part of the water on the table, I suspected it to have been reduced to vapour. I was confirmed in that suspicion afterward when I had filled a like piece of tube with ink and laid it on a sheet of paper, whereon after the explosion I could find neither any moisture nor any sully from the ink. This experiment of the explosion of water, which I believe was first made by that most ingenious electrician, Father Beccaria, may account for what we sometimes see in a tree struck by lightning, when part of it is reduced to fine splinters like a broom; the sap vessels being so many tubes containing a watery fluid, which, when reduced to vapour, sends every tube lengthways. And, perhaps it is this rarefaction of the fluids in animal bodies killed by lightning or electricity, that by separating its fibres renders the flesh so tender and apt so much sooner to putrefy. I think, too, that much of the damage done by lightning to stone and brick walls may sometimes be owing to the explosion of water found during showers, running or lodging in the joints or small cavities or cracks that happen to be in the walls.”

REFERENCES.--Majus--May--(Heinrich), “Disp. de fulmine” and
“Disp. de tonitru,” Marp., 1673, as at Pogg., _Annalen_, Vol.
II. p. 21; Giuseppe Saverio Poli, “La formazione del Tuono,”
etc., 1772, and his other works on the same subject which
appeared during the years 1773, 1779 and 1787; _Phil. Trans._
for 1751, Vol. XLVII. pp. 202, 289, 362; W. de Fonvielle,
“Eclairs et Tonnerres”; “Terrestrial Magn.” for June 1903;
_Jour. of the Franklin Institute_ for 1836, Vol. XVII., p.
183; M. le Docteur Sestier, “De La Foudre”; “Lightning-Rod
Conference,” Reports of Delegates, by G. J. Symons, 1882;
Chap. III. s. 3, vol. i. of Van Swinden’s “Recueil,” etc.,
1784; _Lumière Electrique_, Tome XL. No. 23, p. 497; Giovanni
Cardan’s work, Lyons, 1663; “Library of Literary Criticism,”
C. W. Moulton, Buffalo, 1901–1902, Vol. IV. pp. 79–106; “An
Outline of the Sciences of Heat and Electricity,” by Thos.
Thomson, London, 1830, pp. 347, 423, 432–433; “The Electrical
Researches of the Hon. Henry Cavendish,” Cambridge, 1879, Nos.
350, note, 363; “Works of Benj. Franklin,” Jared Sparks, London,
1882; _Phil. Trans._, Vols. XLVII. p. 565; XLIX. pp. 300, 305,;
L. p. 481; LI. p. 525; LII. 456; also Hutton’s abridgments,
Vol. X. pp. 189, 212, 301, 629, 632; Vol. XI. pp. 189, 435,
609; “Bibliothèque Britannique,” Genève, 1796, Vol. LI. p. 393
(letter to M. Marc Auguste Pictet); Stuber, “Continuation of
the Life of Dr. Franklin”; “An Essay on the Nature of Heat,
Light and Electricity” (on the Franklinian hypothesis), by Chas.
Carpenter Bompass, London, 1817, Chap. III. s. 3, p. 217; “List
of Books written by or relating to Franklin,” by Paul L. Ford,
1889; L. Baldwin, “Mem. of Amer. Acad.,” O. S. I. part i. p.
257; Sturgeon’s “Researches,” p. 524; J. Bart. Beccari, “De
Artif. elect ...”; likewise all the references that are given
at pp. 26–27 of Ronalds’ “Catalogue”; “Journal des Savants” for
June 1817, pp. 348–356.

=A.D. 1752.=--Dalibard (Thomas François), French botanist and amateur in physics, carries out very carefully the suggestions embodied in Franklin’s printed letters and constructs an atmospherical conductor at Marly-la-Ville, about eighteen miles from Paris, where Nollet likewise experimented. Dalibard’s apparatus consisted of a pointed iron rod, one inch in diameter and about forty feet long, which was protected from the rain by a sentry box and attached to three long wooden posts insulated by silken strings.

On the 10th of May, 1752, during Dalibard’s absence, an old soldier by the name of Coiffier, who was at the time employed as a carpenter and who had been left in charge, on observing the approach of a storm, hurried to the apparatus prepared to carry out the instructions previously given him. It was not long before he succeeded in obtaining large sparks on presenting a phial to the rod, and these sparks, which were all accompanied by a large snapping noise, were likewise obtained by the curate of Marly, M. Raulet, whom he had sent for and with whose aid Coiffier subsequently succeeded in charging an electric jar. On the 13th of May, Dalibard made, to the French Academy of Sciences, a report of the results thus obtained by Coiffier, to whom, it may be said, properly belongs the distinction of having been _the first man who saw the electric spark drawn from the atmosphere_.

On the 18th of the same month of May, M. de Lor, of the French University, drew similar sparks from a rod ninety-nine feet high at his house in the Estrapade, at Paris, and the same phenomenon was afterward exhibited to the French King. It is said that the conductor afforded sparks even when the cloud had moved at least six miles from the place of observation. Other experiments of a like nature were made a few days later by Buffon at Montbar, and, during the ensuing months of July and August, in the vicinity of London, by Canton, who, it is said, succeeded in drawing atmospheric electricity by means of a common fishing rod (Dissertation Fifth, Eighth “Britannica,” Vol. I).

An account of the Dalibard and de Lor experiments was transmitted by the Abbé Mazéas, on the 20th of May, to the Royal Society of London.

Mazéas erected, in the upper section of his residence, a magazine consisting of several insulated iron bars connected with the pointed rod. The lightning was brought into the house by means of a projecting wooden pole, having at its extremity a glass tube filled with resin which received a pointed iron rod twelve feet long. This apparatus was, however, too much exposed to afford reliable observations, and Mazéas therefore arranged to make more accurate experiments at the Château de Maintenon, during the months of June, July and October 1753. The results he obtained were communicated to the English Royal Society by Dr. Stephen Hales. The letters of the Abbé Mazéas to the Rev. Stephen Hales, detailing some of M. Le Monnier’s experiments as well as observations made by M. Ludolf at Berlin and transmitted by M. Euler, are to be found at pp. 354–552, Vol. XLVII. _Phil. Trans._ for 1753. For Mazéas, see also _Phil. Trans._, Vol. XLVII. p. 534, Vol. XLVIII. part i. p. 377, and Hutton’s abridgments, Vol. X. pp. 289, 434.

Thomas Ronayne in Ireland, and Andrew Crosse[51] in England (see “Account of an apparatus for ascertaining and collecting the electricity of the atmosphere”) made use of long wires in horizontal positions insulated by being attached to glass pillars, but Mazéas, in his Maintenon experiments, attached the iron wire by a silken cord to the top of a steeple ninety feet in height, whence it entered an upper room of the castle, a total distance of 370 feet. With this, Mazéas ascertained that electric effects are produced at all hours of the day during clear, dry and particularly hot weather, the presence of a thunderstorm not being requisite for the production of atmospheric electricity. In the driest summer nights he could discover no signs of electricity in the air, but when the sun reappeared the electricity accompanied it, to vanish again in the evening about half an hour after sunset.

REFERENCES.--W. Sturgeon, “Lectures,” London, 1842, pp. 182,
183; _Phil. Trans._, Vol. XLVIII. part i. pp. 370, 377, etc.;
Dalibard’s “Franklin,” Vol. II. p. 109, etc.; “Mém. de l’Acad.
des Sciences,” for May, 1762; Nollet, “Letters,” Vol. I. p. 9;
Franklin’s Works, Vol. V. p. 288; English Cyclopædia, “Arts and
Sciences,” Vol. III. pp. 804–805; “Letters of Thomas Ronayne, to
Benjamin Franklin,” at p. 137 of Vol. LXII of _Phil. Trans._,
likewise Ronayne both in _Journal de Physique_, Tome VI, and
in the _Phil. Trans._ for 1772, Vol. LII. pp. 137–140; also
Hutton’s abridgments, Vol. XIII. p. 310; Geo. Adams, “Essay on
Elect.,” London, 1785, p. 259.

=A.D. 1752.=--Freke (John), surgeon to St. Bartholomew’s Hospital, London, gives, in the Second Part of “A Treatise ... of Fire,” the third edition of his “Essay to Show the Cause of Electricity,” etc., originally published in 1746, while in the Third Part of the same work he shows the “Mechanical Cause of Magnetism, and why the compass varies in the manner it does.”

He says (pp. 90–91): “It had been impossible that this wonderful _Phenomenon_ of Electricity should ever have been discovered, if there had not been such things as are non-electricable; for, as fast as this Fire had been driven on anything its next neighbour would have carried it farther; but, when it was most wonderfully found, that anything which was suspended on a silk cord (that being non-electricable) was obliged to retain the Fire, which by Electrical Force was driven on it; and when, moreover, it appeared, that any person or thing, being placed on a cake of beeswax (which is also a non-electricable) could no more part with its Fire than when suspended in [_sic_] a silk cord; I think it will become worthy of inquiry, why they are not electricable.” And, at p. 136, he adds: “I think it a great pity that the word _Electricity_ should ever have been given to so wonderful a _Phenomenon_, which might properly be considered as the first principle in nature. Perhaps the word _Vivacity_ might not have been an improper one; but it is too late to think of changing a name it has so long obtain’d.” In the Third Part, he explains that “by the Fire passing from and to the Sun, it so pervades iron aptly placed, as to make it attractive and produce the various operations of magnetism.”

REFERENCE.--“Gentleman’s Magazine,” London, Vol. XVI for 1746,
pp. 521, 557.

=A.D. 1752.=--In this year was published at Leipzig the “Biblia Naturæ,” written by John Swammerdam, a celebrated Dutch natural philosopher (1637–1682), all of whose works were translated into English and published in folio during the year 1758.

In the second volume of the _Biblia_, he thus alludes to one of many experiments made by him in 1678, before the Grand Duke of Tuscany: “Let there be a cylindrical glass tube in the interior of which is placed a muscle, whence proceeds a nerve that has been enveloped in its course with a small silver wire, so as to give us the power of raising it without pressing it too much or wounding it. This wire is made to pass through a ring bored in the extremity of a small copper support and soldered to a sort of piston or partition; but the little silver wire is so arranged that on passing between the glass and the piston the nerve may be drawn by the hand and so touch the copper. The muscle is immediately seen to contract.”

Through Swammerdam, the Germans lay claim to the origin of what has been called galvanism. It certainly cannot be denied that the above-described experiment closely resembles that which made Galvani famous (A.D. 1786).

REFERENCES.--Swammerdam’s Biography, also Dissertation Fifth,
in the eighth edition “Encycl. Brit.”; the note at p. 491 of
Ronalds’ “Catalogue”; “Gen. Biog. Dict.,” London, 1816, Vol.
XXIX. pp. 45–47; Eloy, “Dict. Hist. de la Méd.,” Vol. IV;
“Biog. Générale,” Vol. XLIV. pp. 706–708; Cuvier, “Hist. des
Sc. Naturelles,” Vol. II. pp. 427–433; Schelhorn, “Amænitates
liter.,” Vol. XIV; “Biblioth. Hulthemiana,” Gand, 1836, Vol. II;
Boerhaave, Preface to “Biblia Naturæ.”

=A.D. 1752.=--On the 16th of April, 1752, is read before the Royal Society a letter written by John Smeaton, a very prominent English engineer and inventor (1724–1792), to Mr. John Ellicot, giving an account of the electrical experiments _in vacuo_ made with his improved air pump at the request of Mr. Wilson. This account, fully illustrated, appears in the Society’s Vol. LXVII for the years 1751 and 1752, pp. 415–428.

He observes that, upon heating the middle of a large iron bar to a great heat, the hot part can be as strongly electrified as the cold parts on each side of it. He also finds that if anybody who is insulated presses the flat part of his hand heavily against the globe, while another person standing upon the floor does the same, in order to excite it, the one who is insulated will hardly be electrified at all; but that, if he only lays his fingers lightly upon the globe, he will be very strongly electrified.

REFERENCES.--Wilson, “Treatise on Electricity,” pp. 129–216;
_Phil. Trans._ XLVI. p. 513; “Dict. of Nat. Biography,” Vol.
LII. pp. 393–395; “Biog. Univ.” (Michaud), Vol. XXXIX. p. 445;
Smile’s “Lives of the Engineers--Smeaton and Rennie”; Flint’s
“Mudge Memoirs,” Truro, 1883.

=A.D. 1752–1753.=--M. de Romas, Assessor to the Presideal of Nerac, in France, repeats the experiment of Benjamin Franklin, and succeeds finally in bringing from the clouds more electricity than had before been taken by any apparatus.

He constructed a kite seven feet five inches high and three feet wide, with a surface of eighteen square feet, and, having wound fine copper wire around a strong cord through its entire length of about eight hundred feet, he raised the kite to a height of five hundred and fifty feet on the 7th of June, 1753. Sparks two inches in length were at first drawn by a discharging rod, and, when the kite was afterwards allowed to reach an elevation of six hundred and fifty feet, he received many flashes one foot long, three inches wide and three lines diameter, accompanied by a noise audible at as great a distance as five hundred feet.

On the 16th of August, M. de Romas raised the kite with about one thousand feet of string and obtained thirty beams of fire, nine or ten feet long and about an inch thick, accompanied by a noise similar to that of a pistol shot (“Encycl. Britannica,” eighth edition, Vol. VIII. p. 582). Three years later, August 26, 1756, and also during the year 1757, De Romas obtained similar results from numerous experiments. He finally apprehended much danger from the raising of the kite and thereafter coiled the string upon a small carriage, which he drew along by means of silken lines as the cord was being unwound.

The researches of De Romas concerning the electricity of isolated metallic bars are embraced in six letters addressed by him to the Bordeaux Academy of Sciences between July 12, 1752, and June 14, 1753. It is reported that they have never been printed and that they are kept, together with other manuscript matter of the same physicist, in the private archives of the institution.

The experiments of De Romas upon isolated bars were first repeated by Boze at Wittenberg, by Gordon at Erfurt, and by Lomonozow in Russia (_Phil. Trans._, Vol. XLVIII. part ii. p. 272). M. Veratti, of Bologna, obtained the electric spark in all weathers, through a bar of iron resting in sulphur, and Th. Marin, of the same city, by means of a long iron pole erected upon his dwelling, studied the relationship of rain and atmospheric electricity (Musschenbroek, “Cours de Physique” Vol. I. p. 397).

REFERENCES.--_Journal des Sçavans_ for October, 1753, p. 222;
“Mémoire sur les moyens,” etc., par De Romas, Bordeaux, 1776;
Sturgeon’s “Annals,” etc., Vol. V. p. 9; Harris, “Electricity,”
p. 176; Priestley, “History,” etc., 1775, pp. 326–329; “Mémoires
de Mathématique,” etc., Vol. II. p. 393, and Vol. IV. p. 514;
“Etude sur les travaux de De Romas,” p. 491, by Prof. Mergey, of
Bordeaux, which latter work won a prize for its author in 1853;
Becquerel, “Traité expérimental,” etc., 1834, Vol. I. pp. 42–43;
likewise the results obtained by Prof. Charles in “Traité de
Physique Expérimentale,” etc., par Biot, Paris, 1816, Vol. II.
pp. 444, 446, and in Peltier’s Introduction to his “Observations
et Recherches Expérimentales,” etc., Paris, 1840, p. 7, as well
as Brisson’s “Dict. de Phys.,” Paris, 1801, Vol. II. p. 174, and
“Mémoires des Savants Etrangers,” 1755, Vol. II. p. 406.

=A.D. 1753=.--M. Deslandes, member of the French Royal Academy of Sciences, is the author of “Recueil de Différents traités de Physique,” the third volume of which contains his memoir on the effects of thunder upon the mariner’s compass. He alludes to the observations made thereon by Dr. Lister of London (well known by his “Historiæ Animalium Angliæ,” Lugd., 1678), as well as to many experiments made by Musschenbroek and by others noted in the _Philosophical Transactions_.

=A.D. 1753.=--Prof. George William Richmann (1711–1753), native of Sweden and member of the Imperial Academy of St. Petersburg, who had already constructed an apparatus for obtaining atmospherical electricity according to Franklin’s plans, was attending a meeting of the Russian Academy of Science, on the 6th of August, 1753, when his ear caught the sound of a very heavy thunder clap. He hastened away in company with his engraver, M. Sokolow, and upon their arrival home they found the plummet of the electrometer elevated four degrees from the perpendicular. Richmann stooped toward the latter to ascertain the force of the electricity, and “as he stood in that posture, a great white and bluish fire appeared between the rod of the electrometer and his head. At the same time a sort of steam or vapour arose, which entirely benumbed the engraver and made him sink on the ground.” Sokolow recovered, but Richmann had met with instant death.

REFERENCES.--“Library of Useful Knowledge,” London, 1829;
“Electricity,” p. 59, also p. 33; “Lettre sur la mort de
Richmann,” par C. A. Rabiqueau, Paris, n. d.; “Comment. Acad.
Petrop.,” XIV. pp. 23, 301–302, also the “Novi Comment.,” IV.
pp. 25, 235 and 299; “Biog. Générale,” Vol. XLII. p. 258;
“Gentleman’s Magazine,” London, Vol. XXIII., 1753, p. 431 and
Vol. XXV. for 1755, p. 3; Singer, “Electricity,” p. 217; Harris,
“Electricity,” p. 177; _Phil. Trans._, Vol. XLVIII. part ii.
pp. 763–765, 772; also Vol. XLIX. part i. pp. 61, 67, and the
abridgments by Hutton, Vol. X. pp. 525, 574–577; “La physique
à la portée de tout le monde,” par le Père Paulian, Vol. II.
p. 357; “Hist. de l’Acad. des Sciences,” pour 1753, p. 78;
“Franklin in France,” 1888, Part. I. p. 5.

=A.D. 1753.=--Canton (John), an English savant (1718–1772), announces his most important discovery that vitreous or resinous electricity may be produced at will in the same tube. This he proves on taking a tube, which had been roughened by grinding it with thin sheet-lead and flour-of-emery mixed with water, and which developed vitreous electricity when rubbed with dry oil silk, and resinous or negative electricity when rubbed with new flannel. Rough quartz will, it is said, show like results. He also took a tube, of which only one-half had been made rough while the other half was polished, and he demonstrated that the different electricities are produced at a single stroke with the same rubber.

He likewise discovered that the exciting power of the rubber or cushion of the electrical machine will be very greatly increased by applying to it an amalgam of mercury and tin mixed with a little chalk or whiting (see Winckler, at A.D. 1733, for the introduction of the cushion).

His very remarkable experiments upon many descriptions of tourmaline, reported to the Royal Society in December 1759, were followed by many others detailed by Priestley, at pp. 298–301 of his “History of Electricity,” London, 1775, and Canton was the first to discover the electrical properties of the topaz, which latter were made known during the early part of the year 1760. (Consult Wilhelm Hankel, “Uber die therm. eigen. des Topases,” Leipzig, 1870.)

He was also the first to establish properly the fundamental fact of electrification by induction, or, as he terms it, “relating to bodies immerged in electric atmospheres,” which afterward led Wilcke (A.D. 1757) and Æpinus (A.D. 1759) to the method of charging a plate of air like a plate of glass, and to make the most perfect imitation of the phenomena of thunder and lightning (George Adams, “Essay on Electricity,” London, 1799, pp. 351–356; Noad, “Manual,” Chapter I, and Priestley, “History,” etc., s. 5). The paper containing an account of Canton’s experiments was read before the Royal Society, December 6, 1753. The principle enounced is that “the electric fluid, when there is a redundancy of it in any body, repels the electric fluid in any other body when they are brought within the sphere of each other’s influence and drives it into the remote parts of the body; or quite out of it, if there be any outlet for that purpose. In other words, bodies immerged in electric atmospheres always become possessed of the electricity contrary to that of the body in whose atmosphere they are immerged.”

Canton is the first to show that the air of a room can be electrified either positively or negatively, and can be made to retain the electricity when received. He thus explains his method: “Take a charged phial in one hand and a lighted candle insulated in the other, and, going into any room, bring the wire of the phial very near to the flame of the candle and hold it there about half a minute, then carry the phial and candle out of the room and return with the pith balls (suspended by fine linen threads) held out at arm’s length. The balls will begin to separate on entering the room and will stand an inch and a half or two inches apart when brought near the middle of it.”

The construction of artificial magnets by Canton, through the combination of the Duhamel (A.D. 1749) and the Michell (A.D. 1750) methods, as well as without the aid of natural loadstones or artificial magnets, is detailed by Noad at Chapter XV of his “Manual,” London, 1859.

REFERENCES.--_Phil. Trans._, Vol. XXXV. p. 137 (Berlinghieri, V.
L.); Vol. XXXVII. p. 294 (Marcel, A.); Vol. XLVII. p. 31; Vol.
XLVIII. part i. pp. 350, 356, and Part II. pp. 780, 782 and 784,
also Vol. XLIX. part i. p. 300; Vol. LI. pp. 398, 403, and Vol.
LII. part ii. pp. 457, 461; and the abridgments of Hutton, Vol.
X. pp. 131, 421, 532; Vol. XI. pp. 421, 609; A.D. 1722, and A.D.
1752; “A Course of Lectures on Nat. Philos. and the Mechanical
Arts,” by Thos. Young, London, 1807, Vol. I. p. 372; II. pp.
64, 243; “The Electrical Researches of Hon. Hy. Cavendish,”
1879, Nos. 117, 205; Descriptions and Drawings of the various
electric friction machines can be seen in Priestley’s “History,”
Plates IV-VIII, and in Albrecht’s “Geschichte d. Electricität,”
1885, pp. 20–30; _Acta Acad. Petr._, I., 1778; “Gentleman’s
Magazine” for Sept. 1759. See likewise the _Phil. Trans._ for
Monday, January 21, 1666, p. 375, and George Adams’ “Essay on
Electricity,” etc., London, 1799, p. 579, for method of making
the artificial Bolonian stone or Canton’s phosphorus.

=A.D. 1753.=--Beccaria (Giovanni Baptista) (1716–1781), a very ingenious and industrious Italian electrician and astronomer, is the author of several quite important works on electricity.

Father Beccaria, as he is sometimes called from having been a member of the religious order of the Pious Schools, proved at the time to be the most indefatigable follower of Franklin in the study of atmospheric electricity. He was the first who recorded the phenomena of thunderstorms, and his many observations thereon are detailed throughout Part I. period x. and s. 10 of Priestley’s great work on electricity. Beccaria says that all clouds, whether of thunder, rain, snow or hail, are formed by the electric fluid; that the electric matter is continually darting from the clouds in one place at the same time that it is discharged from the earth in another; and that the clouds serve as conductors to convey the electric fluid from those places of the earth which are overloaded with it to those which are exhausted of it. Having shown that the polarity of the magnetic needle is determined by the direction in which the electric current has passed through it, he suggests taking the polarity acquired by ferruginous bodies as a test for ascertaining the kind of electricity with which the thunder cloud is charged.

He also shows that the meteor called a _falling star_ is an electrical appearance, explains the cause of the peculiar noise attending the electric spark, and states that the passage of electricity is not instantaneous through the best conductors. He found a spark to occupy at least half a second in passing through 500 feet of wire, and six and a half seconds through a hempen cord of the same length, although when the cord was dampened it passed through it in two or three seconds.

He was the first to show the electric spark while in its passage through water, and he observed that the water sank in the tubes whenever a spark passed from one to the other as the air was repelled by the electric fluid. He found the effect of the electric spark upon water greater than the effect of common fire on gunpowder, and says he does not doubt that, if a method could be found of managing them equally well, a cannon charged with water would be more effective (“dreadful”) than one charged with gunpowder.

He demonstrates that air, contiguous to an electrified body, gradually acquires the same electricity; that the electricity of the body is diminished by that of the air; that there is mutual repulsion between air and the electric fluid, and that the latter, in passing through any portion of air, creates a temporary vacuum.

The production of what he calls his _new inventive phosphorus_ and the method he employs for _revivifying metals_, are described, respectively, at pp. 365 and 282 of his “Lettere dell’ elettricismo.”

REFERENCES.--Beccaria, “Lettere,” etc., Bologna, 1758, pp. 146,
etc., 193, 266, 268, 290, 310, 345; likewise his “Elettricismo
Artificiale,” Turin, 1753, pp. 110, 114, 227; _Phil. Trans._
for 1760, Vol. LI. p. 514; 1762, p. 486; 1766, Vol. LVI. p.
105; 1767, Vol. LVII. p. 297; 1770, Vol. LX. p. 277; 1771, p.
212, also Hutton’s abridgments, Vol. XI. p. 435; Vol. XII, pp.
291, 445; Vol. XIII. p. 50; Wartmann, “Mém. sur les Etoiles
filantes”; Humboldt, “Relation historique,” Tome I; Lardner,
“Lectures,” Vol. I. pp. 429–444; Sturgeon’s _Annals_, Vol. VI.
pp. 415–420, 425–431, and Vol. VIII. p. 180; Noad, “Manual,”
London, 1859, p. 197; Louis Cotte, “Observation ...” Paris,
1769 and 1772; “Mém. de Paris” for the same years and _Jour. de
Phys._ for 1783; Ant. Maria Vassalli-Eandi, “Notizia sopra la
vita ... di Beccaria,” 1816; Carlo Barletti, “Nuove Sperienze
...” Milano, 1771; “Biog. Générale,” Vol. V. pp. 77–78; “The
Electrical Researches of Hon. Henry Cavendish,” Cambridge, 1879,
No. 136; Hale, “Franklin in France,” Boston, 1888, Part I. p.
447; Humboldt, “Cosmos,” London, 1859, Vol. I. pp. 113–136, 202,
337; Vol. V. pp. 217–219, for the observations of Beccaria,
Rozier, Kepler, Benzenberg, Brandes, Bogulawski, Nicholson,
Arago and others on atmospheric electricity, aerolites, etc. See
likewise Beccaria’s letters to Jean Claude Fromond, the Italian
physicist (1703–1795), relating his experiments tending to prove
that electric motions do not occur _in vacuo_, also his letters
to the Princess Giuseppina di Carignano on the electricity of
the moon, as well as to Jean Baptiste Le Roy and to Jacopo
Bartolommeo Beccari relative to experiments with his kite;
“Scelta di Opuscoli,” of Amoretti, Campi, Fromond and Soave,
Vols. XIX. XXI. XXXII.; “Opuscoli Scelti,” II. 378; III. 243,
284, 377; V. 19.

=A.D. 1753.=--Bazin (Gilles Augustin), French physician and naturalist, publishes, at Strasbourg, an illustrated treatise on Magnetic Currents (“Description des Courants Magnétiques,” etc.), which also contains his observations upon the magnet, and a supplement to which appears during the year 1754.

REFERENCES.--“La Grande Encyclopédie,” Vol. V. p. 974; Michaud,
“Biog. Univ.,” Vol. III. p. 353; Ninth “Britannica,” Vol. XV. p.
242.

=A.D. 1753.=--C. M., _i. e._ Charles Morrison and not Charles Marshall, of Greenock, Scotland, writes, from Renfrew, February 1, 1753, to the _Scots’ Magazine_, a letter entitled “An Expeditious Method of Conveying Intelligence,” wherein is first suggested a practical manner of transmitting messages by frictional electricity.

A full copy of this letter appears at pp. 7–9 of Robert Sabine’s “Electric Telegraph,” London, 1872, and at p. 9, 103, No. 570, of the _Scientific American Supplement_ for December 4, 1886, the last-named also reproducing some correspondence establishing the identity of Charles Morrison which was found in the papers of Sir David Brewster.

In the article of Auguste Guérout, which appeared in _La Lumière Electrique_ early in 1883, C. M. is alluded to as Charles Marshall. This is likewise the case in Johnson’s Encyclopædia, 1878, Vol. IV. p. 757. Fahie gives (“History of the Electric Telegraph,” London, 1884, pp. 68–77) a full account of the many inquiries instituted to establish the identity of C. M., which he admits to stand for Charles Morrison, although, at p. 81 of the same work, is given a letter of Sir Francis Ronalds alluding to Charles Marshall, of Renfrew. An article in _Cornhill Magazine_, Vol. II for 1860, pp. 65–66, speaks of an elderly Scotch lady who remembered a very clever man named Charles Marshall, who could make “lichtnin’ write an’ speak” and who could “licht a room wi’ coal-reek” (coal-smoke).

In his remarks upon the afore-named letter, made during the year 1859, Sir David Brewster says: “Here we have an electric telegraph upward of a hundred years old, which at the present day would convey intelligence expeditiously, and we are constrained to admit that C. M. was the inventor of the electric telegraph.... Everything done since is only improvement.”

REFERENCES.--_Scots’ Magaz._, XV. p. 73; “Le Cosmos,” Paris,
Feb. 17, 1854; “Dict. of Nat. Biog.,” Vol. XXXIX. p. 107;
_Athenæum_ of Nov. 5, 1864; Lesage, at A.D. 1774; Th. Du Moncel,
“Exposé des applications de l’électricité,” Paris, 1874, Vol.
III. pp. 1 and 2.

=A.D. 1754.=--Diwish (Prokop), Diviss--Divisch (Procopius), a monk of Seuftenberg, Bohemia (1696–1765), erects, June 15, 1754, a lightning protector upon the palace of the curator of Prenditz, Moravia. The apparatus was composed of a pole surmounted by an iron rod supporting twelve curved up branches and terminating in the same number of metallic boxes filled with iron ore and closed by a boxwood cover traversed by twenty-seven sharp iron points which plunged at their base in the ore. All the system of wires was united to the earth by a large chain. The enemies of Diwish, jealous of his success at the court of Vienna, excited the peasants of the locality against him, and, under the pretext that his lightning rod was the cause of the great drought, they made him take down the lightning rod which he had utilized for six years and then imprisoned him. What is most curious is the form of this first lightning rod, which is of multiple points, like the one M. Melseu afterward invented.

REFERENCES.--_Poggendorff_, Vol. I. p. 580, for Procopius
Divisch’s “Erfand einen Wetter Ableiter”; _Scientific American_,
Sept. 10, 1887, p. 160; “Kronika Prace,” by Pokorny, of Prague;
“Historical Magazine,” Feb. 1868, Art. XII. p. 93; “Prague
News,” for 1754, art. of Dr. Scrinci.

=A.D. 1754.=--Ammersin (Rev. Father Windelinus), of Lucerne, Switzerland, announces in his “Brevis relatio de electricitate,” etc., that wood properly dried till it becomes very brown is a nonconductor of electricity. We have already mentioned the observation made by Benjamin Wilson (A.D. 1746) that, when a dry, warm piece of wood is broken across, one of the pieces becomes vitreously and the other resinously electrified.

Ammersin advises boiling the dried wood in linseed oil or covering it with varnish to prevent the possible return of moisture, and he states that wood thus treated seems to afford stronger appearances of electricity than does even glass (_Phil. Trans._, Vol. LII. part i. p. 342).

REFERENCES.--Ammersin, “Kurze Nachricht,” etc., pub. at Basel,
1771, and translated the same year by Jallabert, who embodied it
in his “Versuche über die Elektricität,” etc.