Chapter XXI: Book I: chap. i. Therein, he says that Baptista Porta, who has made the (6)

=A.D. 1754.=--In his “Dissertations sur l’incompatibilité de l’attraction,” etc., Le Père Gerdil, Professor of Philosophy in the Royal University of Turin, speaks of agencies of which we shall never know anything and of others with which we shall inductively become acquainted, although we shall always ignore many of their respective quantities, qualities and differences. He says that the electric fluid explains the sympathy known to exist between amber and straws--shown by the analogy observed between electricity and magnetism to be the same as that existing between iron and the loadstone.

=A.D. 1754.=--Mr. Strype produces the sixth and last edition of the original “Survey of London” by John Stow, which first appeared during the year 1598.

In his account of Cornehill Ward, allusion is made to the “fair new steeple” of the Church of Saint Michael th’ Archangel, “begun to be built in the year 1421,” and, at p. 74, occurs the following: “As I have oft heard my father report, upon St. James’ night, certain men in the loft next under the bells, ringing of a peal, a tempest of lightning and thunder did arise, an ugly shapen sight appeared to them, coming in at the South window and lighted on the North, for fear whereof they all fell down and lay as dead for the time, letting the bells ring and cease of their own accord; when the ringers came to themselves, they found certain stones of the North window to be razed and scratched, as if they had been so much butter, printed with a lion’s claw; the same stones were fastened there again and so remain to this day.”

In one of the notes to William T. Thoms’ reprint of the above-named “now perfectly invalyable” work, he says: “It is quite clear from the tone in which Stow speaks of this ‘ugly shapen sight’ and the marks ‘printed with a lion’s claw,’ that he suspected this instance of the power of the electric fluid to be nothing less than a visitation from the foul fiend himself.”

Speaking of St. Paul’s Cathedral, Stow tells us that its pulpit cross “was by tempest of lightning and thunder defaced,” and that “on Wednesday, the fourth of June (in the year 1561), betweene three, four and five of the clock, in the after-noone, the steeple of Paule’s in London, being fired by lightning brast forth (as it seemed to the beholders) two or three yards beneath the foote of the crosse, and from thence burnt downe the speere to the stone worke and bels, so terribly, that within the space of foure houres, the same steeple with the roofes of the church ... were consumed.” Very curious and interesting reading will be found in the “Burnynge of Paule Church, London, in 1561, and the iiii day of June, by lyghtnynge at three of the clocke ...” by Wyllyam Seres, London, 1563; as well as in his previous work on like subject, published in 1561. See Report in “Archæologia,” London, 1794, Vol. XI. pp. 72–86; likewise the entry at A.D. 1769, relative to another lightning stroke in 1772.

Stow is perhaps best known by his “Annales, or a Generalle Chronicle of England.” In that portion of the latter work devoted to “the life and raigne of Queene Elizabeth” he states (London ed., 1631, p. 809) “that the knowledge and use of the sea compasse or needle was neither familiar nor understood but few yeeres before” the time of the navigators John Hawkins, Francis Drake, Martin Frobisher and Thomas Candish, and he adds (at p. 810) “that the honour of that invention, as touching the propertie of the Magneticall needle in pointing towards the Poles is attributed by (Flavius) Blondus in his _Italia Illustrata_ (in the description of Campadia Felix) and by the great writer Paulus Jovius in lib. xxv. of his History in the end [_sic_], to the citizens of Amalfi.... The author’s name is no more particularly recorded, then [_sic_] to be one Flavio ... for to him that honour is given by Francis Lopez, of Gomara, in his West Indian History, lib. i. cap. 9, and by Peter Ciezius, in lib. ii. cap. 9, of his Indian Story, and by Pandulph: Collenutius in his History of Naples, who, three hundred yeeres since, namely in the yeere of our Saviour 1305, discovered that propertie in the Magnes and applied it to navigation” (see, for Flavius Blondus: George Hakewill, “An apologie,” etc., Oxford, 1635, lib. iii. s. 4, and lib. v. p. 60; “Blondi Flavii Fortiriensis ... Italia Illustrata,” 1531, folio; Flavius Blondus (Flavio Biondo), “Roma Ristaurata et Italia Illustrata,” Vinezia, 1558, 12mo; Niceron, “Mémoires ... des hommes illustres,” Paris, 1731, Vol. XVI. pp. 274–281).

A contemporary of Flavius Blondus, by name Michael Angelus Blondus (1497–1560), author of “De Ventis et Navigatione,” published at Venice in 1546, likewise alludes to the polarity of the needle, and gives a curious illustration of a mariner’s compass at Chap. XXIV. p. 15, of the last-named work. (For M. A. Blondus, see “La Grande Encyclopédie,” Vol. VI. p. 899.)

Stow makes reference (p. 810) to Dr. Gilbert’s _De Magnete_, to the “diuision of the plot or playne of the compasse into the thirty-two points,” considered by “Goropius in his lib. iii. _De Origin. Hispanicis_, to have been the inuention of some Germane,” and to the manner and “meanes saylers vsed to sayle, before they atteined the knowledge of the compasse.”

=A.D. 1755.=--Eeles--Eales (Henry), a prominent scientist of Lismore, Ireland, communicates to the Royal Society, on the 25th of April, 1755, a paper concerning the electrical property of steam and exhalations of all kinds. Eeles’ theory of the electricity of vapour (“On Vesicles and Atmospheres of Electricity”), afterward developed by Sir John Herschel, is fully explained in the “Encycl. Brit.” article on “Meteorology” (par. 135, etc.), and is also alluded to at p. 43 of Harris’ “Electricity” as well as at p. 153, Vol. XLIX. part i. of the _Philosophical Transactions_.

Mr. Eeles showed, that while the Leyden jar is being charged, both the inside and the outside have the same kind of electricity and that the negative electricity does not appear until the machine has ceased turning. Eeles’ hypothesis, extracted from his “Philosophical Essays,” and from the analysis of a course of lectures delivered at Trinity College, Cambridge, by Mr. Atwood, is treated of at length by George Adams in the fourth chapter of his “Essay on Electricity,” wherein pertinent allusion is also made to the fact of Mr. Eeles having been purposely shut out of Priestley’s “History and Present State of Electricity.”

REFERENCES.--_Philosophical Transactions_, Vol. XLVII. p. 524;
_Phil. Mag. and Journal_, Vol. XLIV. p. 401 (1814).

=A.D. 1756.=--Le Chevalier Jacques C. F. de la Perriere de Roiffé (not Reiffé) is the author of “Méchanismes de l’Electricité et de l’Univers,” published at Paris, wherein he pretends to account for all electrical phenomena.

At p. 12 of his Préface, he curiously states that as everybody comprehends the distinction between elastic and non-elastic bodies, likewise the existence, nature and diversity of the properties of atmospheric fluids, with which all bodies are impregnated and by which they are surrounded, also the various expansive modes of activity to which they are subject, as well as their immiscibility as regards the surrounding air, without which latter they could not, however, subsist, he will in his new theory apply these principles to the mechanisms of electricity and of the universe as affected by the general laws and the invariable results attaching to shock and motion.

=A.D. 1756.=--In the “Subtil Medium Proved,” etc., of Mr. R. Lovett, lay-clerk of the cathedral church at Worcester, England, are shown numerous medical cures successfully made by electricity. He asserts that the electric fluid is almost a specific in all cases of violent pains, like obstinate headache, the toothache, sciatica, etc., but that it has not succeeded so well in rheumatic affections. He states that electricity properly administered has never caused injury, and he alludes to equally successful cures made by the Rev. John Wesley and by Dr. Wetzel, of Upsal.

The well-known physician, Antonius de Haen, during several years’ experience, made many cures of paralysis, St. Vitus’ dance, etc., by the agency of electricity, as related in his _Ratio Medendi_, Vol. I. pp. 199, 200, 233, 234 and 389. Allusion has been made in these pages to the employment of electricity for medical purposes by Kratzenstein (A.D. 1745) and by Jallabert (A.D. 1749), and Priestley named many others who have likewise used it successfully in their practice.

REFERENCES.--“Subtil Medium Proved,” etc., pp. 76, 101 and 112;
also his “Philosophical Essays,” Worcester, 1761 and 1766, and
his “Electrical Philosopher,” 1774; Wesley’s “Desideratum,
or Electricity made Plain and Useful,” p. 3; Joseph Veratti,
“Observations ... pour guérir les paralytiques....” La Haye,
1750.

=A.D. 1757.=--Dr. Darwin, of Lichfield, addresses to the Royal Society of London a paper which is read May 5, 1757, and in which he gives an account of experiments to prove that the electric atmosphere does not displace air, and that all light, dry, animal and vegetable substances, in particular, are slow to part with the electricity with which they have been charged (_Phil. Trans._, Vol. L. part i. pp. 252 and 351).

=A.D. 1757.=--Euler (Leonard), a native of Switzerland, who studied under the Bernoullis, and who succeeded Daniel Bernoulli as Professor of Mathematics at St. Petersburg, was undoubtedly one of the greatest analysts the world has ever produced (“Encycl. Brit.,” Fifth Dissertation of the eighth edition, Vol. I. p. 742).

He adopted the theory of Descartes that the magnetic fluid moves from the equator to the poles, and he endeavoured to determine mathematically the course of the magnetic needle over the earth’s surface. He announces that “the magnetic direction on the earth follows always the small circle which passes through the given place and the two magnetic poles of the earth,” or, as worded by Sir David Brewster, that “the horizontal needle is a tangent to the circle passing through the place of observation and through the two points on the earth’s surface where the dipping needle becomes vertical or the horizontal needle loses its directive power.”

He entertained very peculiar ideas regarding the source of power in the loadstone, the pores of which he imagined were filled with valves admitting of the entrance of the current and preventing its return. His notions on this subject are best given in his own words: “Non-magnetic bodies are freely pervaded by the magnetic matter in all directions; loadstones were pervaded by it in one direction only ... water, we know, contains in its pores particles of air ... air, again, it is equally certain, contains in its pores a fluid incomparably more subtile, viz. _æther_, and which, on many occasions, is separated from it, as in Electricity; and now we see a still further progression, and that ether contains a matter much more subtile than itself--the magnetic matter which may, perhaps, contain in its turn others still more subtile.... The loadstone, besides a great many pores filled with ether, like all other bodies, contains some still much more narrow into which the _magnetic matter_ alone can find admission. These pores are disposed in such a manner as to have communication with each other, and constitute tubes or canals through which the magnetic matter passes from the one extremity to the other. Finally, this matter can be transmitted through these tubes only in one direction, without the possibility of returning in the opposite direction.... As we see nothing that impels the iron toward the loadstone, we say that the latter attracts it. It cannot be doubted, however, that there is a very subtile, though invisible matter, which produces this effect by actually impelling the iron towards the loadstone.”

REFERENCES.--“Journal des Savants” for March and April 1868;
Euler’s “Letters,” translated into English, 1802, Vol. I. p.
214, and Vol. II. pp. 240, 242, 244; “Berlin Memoirs,” for
1746, p. 117; 1757, p. 175; 1766, p. 213; _Poggendorff_, Vol.
I. p. 702; “Nova Act. Petropol.” for 1779, Vol. III; “Pièces de
Prix de l’Acad. des Sc. de Paris,” Vol. V. Mém. II and IX, this
last-named publication, containing likewise a joint Memoir of D.
Euler, J. Bernoulli and E. F. Dutour upon the mariner’s compass,
which appeared in Paris during 1748; Whewell, “History of the
Inductive Sciences,” 1859, Vol. I. pp. 225, 367, 370; Vol. II.
pp. 32, 40.

His son, Albert Euler, censured Halley’s magnetical hypothesis, and proposed, in 1766, a theory requiring the assumption of only two poles, distinct, however, from those of the terrestrial axis.

=A.D. 1757.=--Dollond (John), who was at first a silk weaver at Spitalfields, England, which occupation he abandoned in order to give his exclusive attention to scientific experimental studies, discovered the laws of the dispersion of light and constructed the first achromatic telescope as well as several improved instruments for magnetic observations. A full description of the most important of these, accompanied by illustrations, can be found in the articles of the “Encyclopædia Britannica” on magnetic instruments.

REFERENCES.--Kelly’s “Life of John Dollond,” London, 1808;
_Phil. Mag._, Vol. XVIII. p. 47; Thomas Thomson, “Hist. of Roy.
Soc.,” London, 1812, pp. 379–382; “Directions for using the
Electric Machine made by P. and J. Dollond,” London, 1761.

=A.D. 1757.=--Wilcke (Johann Karl), a very distinguished scientist of Stockholm (1732–1796), introduces new phenomena respecting the production of electricity produced by melting electrical substances, which he discovers in continuation of experiments begun by Stephen Grey. He gives the name of _spontaneous_ to the electricity produced by the liquefaction of electrics, observing that the electricity of melted sulphur does not appear until it commences to cool and to contract, its _maximum_ being reached at its point of greatest contraction. Melted sealing wax, he says, becomes negatively electrified when poured into glass, but, when poured into sulphur, it is positively electrified, leaving the sulphur negative (Sir Humphry Davy, “Bakerian Lectures,” London, 1840, p. 36 and notes).

While in Berlin, he and Æpinus investigate the subject of electric atmospheres, and they are led to the discovery that plates of air can be charged in the same manner as plates of glass. (See Canton, A.D. 1753.) This they did by suspending large wooden boards, which were covered with tin and whose flat surfaces were held parallel to and near each other. They found that upon electrifying one of the boards positively the other was always negative, and that with them could be given shocks like those produced by a Leyden jar. They likened the state of the boards to the condition of the clouds and the earth during a thunderstorm, the earth being in one state and the clouds in the opposite, the body of air between them answering the same purpose as the small plate of air between the boards or the plate of glass between the two metallic coatings of the Leyden jar.

In Wilcke’s treatise, alluded to below, he defines the two electricities much more clearly than had previously been done. He distinguishes three causes of excitation, viz. _warming_, _liquefaction_ and _friction_; the _spontaneous electricity_ already alluded to, he further says, is the result of the apposition or mutual action of two bodies, in consequence of which one of them is electrified positively and the other negatively; _communicated electricity_, on the other hand, is that which is superinduced upon the whole or part of a body, electric or non-electric, without the body having been previously heated, melted or rubbed, or without any mutual action between it and any other body. This distinction is, in general, very obvious, but Mr. Wilcke defines it throughout his work in a very clear manner, citing cases wherein they are frequently confounded.

Wilcke and Anton Brugmans (A.D. 1778) first propounded the theory of two magnetic fluids, which was afterward established by Coulomb (A.D. 1785) and perfected by the great mathematician Poisson (A.D. 1811). The hypothesis of the two fluids supposes that a magnet contains minute invisible particles of iron, each of which possesses by itself the properties of a separate magnet. It is assumed that there are two distinct fluids--the _austral_ and the _boreal_--which reside in each particle of iron. These fluids are inert and neutral when combined, as in ordinary iron, but when they are decomposed the particles of the _austral_ attract those of the _boreal_, and _vice versa_, while they each repel one another.

REFERENCES.--Wilcke, “Disputatio inauguralis physica,” etc.,
published Rostock, 1757, also his “Herrn Franklin’s briefe von
der electricitat,” etc., Leipzig, 1758, his “Jal om Magneten,”
1764, and his “Über den Magneten,” Leipzig, 1758; besides
1794–1795; likewise his different Memoirs in the “Swedisches
Musæum,” Vol. I. p. 31, and in both the “Schwedischen Akad.
Abhandlungen,” etc. (also _Neue Abhand_.) and the “Vetensk Acad.
Handl.” for 1758, 1759, 1761–1763, 1766–1770, 1772, 1775, 1777,
1780, 1782, 1785, 1786, 1790; “The Electrical Researches of Hon.
Hy. Cavendish,” 1879, No. 134.

=A.D. 1759.=--Hartmann (Johann Friedrich), of Hanover, is the author of three works on electricity, published in that city during 1759, 1764 and 1766, wherein he gives an account of several very curious electrical experiments. One of the most interesting of these demonstrates the progressive motion of the electrical discharge. When he passes the shock through many small cannon balls, sometimes to the number of forty, placed upon small drinking goblets close by one another, all the sparks are seen and all the cracklings are heard at the same moment; but when he substitutes eggs (preferably ten or twelve) for the balls, the progress of the explosion is visible, every two giving a flash and a report separately.

He remarks that upon one occasion, as he re-entered a room which he had just before left, after making therein a number of experiments, he observed a small flame following him as he walked about swiftly while holding a lighted candle in his hand. The flame vanished whenever he stopped to examine it, and he attributed its appearance to the presence of sulphur thrown into the air by continued violent electrification.

REFERENCES.--Hartmann, “Abhandlung von der verwandschaft,” etc.,
Hanover, 1759, pp. 58, etc., and 135; also his “Electrische
experimente,” etc., Hanover, 1766, and his “Anmerkungen,” etc.,
1764, 4to, p. 38; Friedrich Saxtorph, “Elektricitätsläre,”
Vol. II; _Hamburgisches Magazin_ (also _Neues Hamb. Mag._)
for 1759, Vol. XXIV, and for 1761, Vol. XXV; “Nov. Acta Acad.
Nat. Curios,” Vol. IV. ss. 76–82, 126; “Göttingischen gemein.
Abhand.,” von Jahr 1775.

=A.D. 1759.=--Wesley (John), the founder of Methodism (1703–1791) and the most eminent member of a very distinguished English family, publishes “The Desideratum; or Electricity made Plain and Useful, by a Lover of Mankind and of Common-sense.” In this, he relates at great length the cures of numerous physical and moral ailments, attributed to the employment of the electric fluid, under such curious headings as “Electricity, the Soul of the Universe,” “Electricity, the Greatest of all Remedies,” etc. (“The Library of Literary Criticism,” C. W. Moulton, Buffalo, 1901–1902, Vol. IV. pp. 110–129).

=A.D. 1759.=--Æpinus (Franz Maria Ulrich Theodor) (1724–1802), celebrated German natural philosopher, member of the Scientific Academies of Berlin and St. Petersburg, publishes in the latter city his most important work, “Tentamen Theoriæ Electricitatis et Magnetismi,” wherein he adopts, as did Wilcke, all the general principles of Franklin’s theory of positive and negative electricities. Therein he also shows that the phenomena of electricity depend mainly upon the tendency of the fluid to attain a state of equilibrium by passing from bodies containing an excess to others which have less than the natural quantity; that the electric fluid existing in the pores of all bodies moves without obstruction in non-electrics and with much difficulty in electrics; that all bodies contain a fluid whose particles mutually repel one another with forces decreasing as the distance between them increases, and, according to the same law, attract the particles of the bodies with which they are in combination.

It has already been shown that, in conjunction with Wilcke, he found the means of charging a plate of air. This experiment, suggested by some of the observations made by Canton and Franklin, led to what may be considered one of the greatest discoveries in the science of electricity, for in this was first demonstrated the grand principle of induction (see Grey at A.D. 1720), and the result led to Volta’s discovery of the _electrophorus_. Volta, also, was the first to apply to an electrometer the apparatus invented by Æpinus for condensing electricity.

Æpinus first discovers to its fullest the affinity existing between electricity and magnetism, explaining nearly all the phenomena of magnetism (“De Similitudine vis electricæ et magneticæ”; “Similitudinis effectuum vis magnet. et. elect.: novum specimen” in the “Novi Comment. Acad. Petrop.,” Vol. X. p. 296). He improves upon the methods employed by both Duhamel and Michell for the construction of artificial magnets in a different line from that employed by John Canton, A.D. 1753. He lays the bar to be magnetized upon the ends of the opposite poles of two powerful field magnets, and places two bunches of magnetic bars upon the middle of the bar, separating the bunches by a piece of wood and keeping together the poles of each of the same name as that of the powerful fixed magnet nearest to it. These two bunches are then held at an inclination of 15 to 20 degrees, and are drawn away from each other to the end of the bar which is to be magnetized, so that each half of the bar receives the same number of strokes. When the bar is very thick, the process should be repeated upon its reverse, and in order to make the result more effective, the united ends of the bars should at the outset be ground together, and pressure should be applied while the operation is going on.

Æpinus was the first to discover the polarity of the tourmaline. After M. Lechman acquainted him with its attractive power, he made many experiments, of which he communicated the very important results, during the year 1756, to the Academy of Sciences and Belles-Lettres at Berlin. Up to this time but little was known regarding the necessity of heat to excite the tourmaline. Æpinus found that he could electrify it to a high degree by placing the stone in boiling water, and that it was necessary to heat it to between 99½ degrees and 212 degrees Fahrenheit to develop its attractive powers. One of the extremities of the tourmaline terminated by the six-sided pyramid then becomes charged with positive electricity, while the other extremity is negative. When the stone is of considerable size, flashes of light can be seen along its surface.

M. De Romé Delisle, in his “Essai de Cristallographie,” Paris, 1772, p. 268, alludes to what has already been stated relative to the necessity of heating the tourmaline (see J. G. S. at A.D. 1707, and Leméry at A.D. 1717), and he gives an extract from the work attributed to Adanson, as mentioned at A.D. 1751. Delisle’s references embrace: “Act. Paris,” 1717, p. 9; “Act. Berolin,” 1756, p. 105; “Lettre du Duc de Noya Caraffa à M. de Buffon,” Paris, 1759; _Ascendrecker, Aschentrecher, Aschenzicher_ (_tire-cendre_), “Trip: Tourmaline, Vog. min.” 191; “Act. Holmens,” 1768, p. 7; besides, at pp. 209, 233 and 245 he speaks of the electrical and phosphorescent properties of crystals, showing that the _lapis lyncurius_ of the ancients is the hyacinth or zircon of to-day (see B.C. 321), and not, as many believe, either amber or belemnite (_pierre de foudre_, _lapis fulminaris_), while the hyacinth of old was a purple stone which, if now found, would be classed among the amethysts.

REFERENCES.--“Allgemeine Deutsche Biographie,” Leipzig, 1875,
Vol. I. p. 129; Æpinus, “Sermo Acad. de similitudine,” etc.,
1758, and his “Recueil ... sur la tourmaline,” 1762; “Novi. Com.
Petropol.,” for 1761, 1764, 1768; “Acta Acad. Moguntinæ,” Vol.
II. p. 255; Leithead, “Electricity,” p. 289; _Phil. Trans._,
Vol. LI. p. 394, and Vol. LVII. part i. p. 315; “Encycl. Brit.,”
articles “Electricity” and “Magnetism”; Bigeon’s report in the
“Annales de Ch. et de Phys.,” 2^e série, Tome XXXVIII. p. 150;
Van Swinden, “Recueil,” etc., La Haye, 1784, Vols. I and II
_passim_; Becquerel in _Annales de Chimie et de Physique_, Vol.
XXXVI. p. 50; Thomson, “Hist. Roy. Soc.,” 1812, p. 184; “The
Electrical Researches of the Hon. Henry Cavendish,” Cambridge,
1879, Nos. 1, 134, 340 and 549; Lord Kelvin (Sir Wm. Thomson),
“Æpinus atomized,” in _Phil. Mag._ for March 1902, p. 257, etc.,
and in _Journal de Physique_ for Sept. 1902, p. 605.

=A.D. 1759.=--Symmer (Robert) assails the theory announced by Dufay (see Franklin, A.D. 1752), and shows, in a paper submitted to the Royal Society, December 20, 1759, that all the electrical phenomena are produced by two distinct but coexistent fluids not independent of, but counteracting each other. He says that equal quantities of these fluids are contained in all bodies while in their natural condition; that when a body is positively electrified it does not hold a larger share of electric matter, but a larger portion of one of the active powers, and when negatively electrified a larger portion of the other, and not, as Franklin’s theory supposes, an actual deficiency of electric matter. Symmer’s theory is perhaps best explained in his own words, as follows: “It is my opinion that there are two electric fluids (or emanations of two distinct electric powers), essentially different from each other; that electricity does not consist in the efflux and afflux of these fluids, but in the accumulation of the one or the other in the body electrified; or, in other words, it consists in the possession of a larger portion of the one or of the other power than is requisite to maintain an even balance within the body, and lastly, that according as the one or the other power prevails, the body is electrified in one or the other manner.”

Very curious reading may be had by reference to the volumes of the _Philosophical Transactions_ named below, in which Symmer details many experiments with pieces of silk, as well as with white and coloured, new and newly cleansed silk and worsted stockings. Therein he shows his ability to charge the Leyden jar with either positive or negative electricity, according as he presents a black or white stocking to the wire of the phial. These experiments, which Symmer admits to have made for the express purpose of proving the existence of two electricities, further illustrate the phenomenon of electrical cohesion, although the latter is still better demonstrated by means of panes of ordinary glass. He thus expresses himself: “Upon these considerations, we may expect, from the experiment in hand, the means of determining whether the distinction of electricity into two different kinds is merely nominal, or if there is an essential difference between them; for, after the glass plates have been electrified in one position, so as to be incapable of receiving any more electricity, if they be inverted, and in that new position presented to the chain and wire, and the globe again be put in motion, according as one or other of those opinions hold, corresponding effects will follow.”

Symmer also proves his two distinct powers of electricity by the experiment of passing the electric shock through a quire of paper instead of through a single card (“Lib. Useful Knowledge,” London, 1829, “Electricity,” p. 44).

REFERENCES.--“Electricity in the Service of Man,” R. Wormell,
London, 1900, p. xiv; _Philosophical Transactions_, Vol. LI.
part i. pp. 171, 340, 366, 373, etc., 389, and Vol. LVII. p.
458; also Hutton’s abridgments, Vol. XI. p. 405; Nollet,
“Lettres,” etc., Vol. III. p. 42; “Encycl. Brit.,” article
“Electricity”; “Library of Useful Knowledge,” London, 1829,
“Electricity,” Nos. 160 and 161.

=A.D. 1760.=--Mayer (Johann Tobias, Sen.) (1723–1762), one of the most celebrated German astronomers, director of the observatory at Göttingen, is the first to make known the law of the inverse square resulting from actual experimental investigation. This he does in a paper, “Inclination and Declination of the Magnetic Needle, as deduced from theory,” read before the Royal Society at Göttingen, wherein he states that the intensities of the magnetic attractions and repulsions vary inversely as the squares of the distances from the pole of a magnet. Consult “Magnetism,” in the ninth edition of the “Encyclopædia Britannica,” for additional reference to the above paper, also section 14 of the same work for an account of Mayer’s dipping needle as constructed by General Sabine.

REFERENCES.--Delambre’s notice of the life of J. T. Mayer in the
“Biographie Universelle”; Hutton’s “Mathem. Dict.”; Montucla,
“Histoire des Mathématiques”; list of his works added to the
éloge pronounced by Kaestner, Göttingen, 1762; “Abhandlungen
von Galvani und andern,” Prague, 1793; Whewell, “History of
the Inductive Sciences,” 1859, Vol. II. pp. 206, 221; Coulomb,
“Mémoires Acad. Paris” for 1786 and 1787; “Royal Soc. Cat. of
Sc. Papers,” Vol. IV. pp. 311–314; Lambert, “Reports of the
Berlin Academy” for 1776.

Mayer (Johann Tobias, Jr.), 1752–1830, is the author of Memoirs on the magnetic needle as well as upon many electrical experiments, of which details may be found in the _Journal der Physik_ of Friedrich A. C. Gren and in the “Comment Soc. Göttingen recent.”

=A.D. 1760.=--Delaval (E. H.) communicates between 1760 and 1764 several papers to the London Royal Society in reference to experiments made for the purpose of ascertaining the conducting powers of a body in different states. Therein, he shows that animal and vegetable substances lose their conducting powers when reduced to ashes, and that while metals are the best conductors, their oxides are non-conductors. His experiments made with _island_ (Iceland) _crystal_ (well known for its extraordinary property of double refraction), proved that it is affected by heat differently from other substances named, since the temperature necessary to render them electric makes the crystal non-electric. He had a piece of crystal of which, he said, one part became non-electric when greatly heated, while the other part, with the same or even a much greater heat, remained perfectly electric. These experiments did not, however, succeed with Sir Torbern Bergman, who repeated them with great care and who found that _island crystal_ was a conductor in all cases, to whatever degree of heat it was exposed.

REFERENCES.--_Phil. Trans._, Vol. LI. part i. p. 83; Vol LII.
part i. pp. 353, etc., and part ii. p. 459; also Vol. LIII.
part i. pp. 84–98; and Hutton’s abridgments, Vol. XI. pp. 334,
589; Vol. XII. p. 140; Thomas Thomson, “Hist. of Roy. Soc.,” p.
443; Thos. Young, “Course of Lectures,” 1807, Vol. II. p. 679,
for notes on Dr. Wm. H. Wollaston’s paper concerning the double
refraction of Iceland crystal.

=A.D. 1760–1762.=--Bergman--Bergmann--(Torbern Olof), celebrated Swedish astronomer, naturalist and chemist, writes several letters to Mr. Wilson, which are read before the Royal Society, Nov. 20, 1760, and March 18, 1762, wherein he alludes to the possibility of electrifying plates of ice in the same manner as plates of glass. In a subsequent letter he details experiments with silk ribbons of different colours, almost as curious as those of which an account has already been given (by Symmer at A.D. 1759), and from which he concludes that there is a certain fixed order regarding positive and negative electricity in which all bodies may be placed while other circumstances remain unchanged.

REFERENCES.--Bergman’s “Bemerkung ... Isländischen Krystales,”
“Comment ... electrica turmalini,” “Elektrische Versuche,”
etc., and his other works referred to in the _Philosophical
Transactions_, Vol. LI. p. 907; Vol. LIII. p. 97; Vol. LIV. p.
84; Vol. LVI. p. 236; also Hutton’s abridgments, Vol. XI. pp.
506, 705; Vol. XII. pp. 109, 343; “Nova Acta Soc. Upsal.,” “K.
Schwedischen Akad. Abhand.,” “Aus dem Schwed. Magazine,” _Phil.
Mag._, IX. p. 193; “Eng. Cycl.,” Vol. I. pp. 664–665; Gmelin’s
“Chemistry,” Vol. I. p. 320; Thomas Thomson, “Hist. of the Royal
Society,” London, 1812, pp. 444, 475–477.

=A.D. 1761.=--The many experiments made at this period by Ebenezer Kinnersley, of Philadelphia, relative to the two contrary electricities of glass and sulphur, are endorsed by his close friend Benjamin Franklin in his _Letters_ at pp. 99, 100 and 102–105. He makes several curious observations on the elongation and fusion of fine iron wires whenever a strong charge is passed through them while in a state of tension, to which Dr. Watson makes special reference in a paper read before the Royal Society. He believes that lightning does not melt metal by a cold fusion, as Dr. Franklin and himself had formerly supposed, and that when it passes, for instance, through the blade of a sword, if the quantity is not very great, it may heat the point so as to melt it, while the broadest and the thickest part may not be sensibly warmer than before.

To ascertain the effects of electricity upon air, Kinnersley devised an instrument which he called an _electrical air thermometer_, and which is described at p. 626, Vol. VIII of the 1855 “Encyclopædia Britannica.” With this he could show the sudden rarefaction which air undergoes during the passage of the electric spark through it, heat being produced without accompaniment of any chemical change in the heated body.

Some other important observations made by Kinnersley, who, besides being an intimate friend, was the original associate of Ben. Franklin, are summed up as follows: A coated flask containing boiling water cannot be charged, the electricity passing off with the steam; but when the water gets cold the flask may be charged as usual. A person in a negative state of electricity standing upon an electric, and holding up a long sharp needle out of doors in the dark, observes light upon the point of it. No heat is produced by electrifying a thermometer, nor by passing shocks through large wire, but small wire is heated red-hot, expanded and melted (_Phil. Trans._ for 1763, Vol. LIII. p. 84; Thomson, “Hist. Roy. Soc.,” p. 445).

In the New York “Electrical Review” of May 13, 1905, will be found the following curious reference to the Boston Art Club exhibits of President R. H. W. Dwight:

“Among these is an interesting broadside, which gives a summary of two lectures on electricity by Ebenezer Kinnersley delivered in Faneuil Hall in September, 1751--the first lectures probably ever delivered on the then new subject of electricity. Kinnersley was an Englishman, who was head master in English literature in the College of Philadelphia, from 1753 to 1773, a student of science, who made a number of discoveries in electricity and invented a number of quaint electrical devices. He and Franklin were on intimate terms, and were closely associated in their electrical experiments. Kinnersley has been erroneously cited as an anticipator of Oersted’s discovery of the deflection of a magnetic needle by an electric current. The former’s experiment, however, was purely electrostatic. In the summary of these two lectures, among other things, it states that electricity ‘is an extremely subtile fluid; that it doth not take up any perceptible time in passing through large portions of space; that it is mixed with the substance of all other fluids and solids of our globe; that our bodies at all times contain enough of it to set a house on fire.’”

The exhibits of President Dwight are:

“An artificial spider animated by the electric fire so as to act like a live one; a shower of sand which rises again as fast as it falls; a leaf of the most mighty of metals suspended in the air, as is said of Mahomet’s tomb; electrified money which scarce anybody will take when offered to them; a curious machine, acting by means of the electric fire, and playing a variety of tunes on eight musical bells.”

This broadside of 1751 appears to antedate any other similar notice of electrical experiments.

The “Electrical Review” of April 23, 1904, p. 621, had published copy of an advertisement from the Massachusetts _Gazette_ of March 7, 1765, giving notice of a course of lectures by David Mason, illustrated by “entertaining experiments on electricity similar to those cited in the broadside under date of 1751.” The advertisement of 1765, here referred to, appears at A.D. 1771.

REFERENCES.--Sturgeon’s “Lectures,” London, 1842, p. 169; “The
Electrical Researches of Hon. Henry Cavendish,” 1879, Nos. 125,
137, 213; _Phil. Trans._, Vol. LIII. part i. pp. 84–87; Vol.
LIV. p. 208; Vol. LXIII, 1773, part i. p. 38; also the Hutton
abridgments, Vol. XI. p. 702, and Vol. XIII. p. 370; Bertholon,
“Elec. du Corps Humain,” 1786, Vol. I. pp. 23, 33, 214, 217, 220.

=A.D. 1762.=--Sulzer (Johann Georg), a Swiss philosopher, member of the Berlin Academy of Sciences, in his “Theory of Agreeable and Disagreeable Sensations” (“Theorie d. angenehmen u. unangenehmen Empfindungen,” Berlin, 1762), thus expresses himself: “When two pieces of metal, one of lead and the other of silver, are so joined together that their edges make one surface, a certain sensation will be produced on applying it to the tongue, which comes near to the taste of martial vitriol (vitriol of iron); whereas each piece by itself betrays not the slightest trace of that taste” (F. C. Bakewell, “Manual of Electricity” London, 1857, Chap. III. p. 28).

The passage in the edition “Nouvelle Théorie des Plaisirs,” published in 1767, is thus given by Sabine, “Electric Telegraph,” 1872, p. 15: “On taking two pieces of different metals--silver and zinc--and placing one of them above and the other underneath his tongue, he found that, so long as the metals did not make contact with each other, he felt nothing; but that when the edges were brought together over the tip of his tongue, the moment contact took place and during the time it lasted, he experienced an itching sensation and a taste resembling that of sulphate of iron....” Sulzer does not appear to have been much surprised at the result, thinking it “not improbable that, by the combination of the two metals, a solution of either of them may have taken place, in consequence of which the dissolved particles penetrate into the tongue; or we may conjecture that the combination of these metals occasions a trembling motion in the respective particles, which, exciting the nerves of the tongue, causes that peculiar sensation.”

And thus, remarks Pepper, a prominent fact has slept in obscurity from the time of Sulzer to the time of Galvani.

REFERENCES.--Izarn, “Manuel,” Paris, 1804, p. 4; Sturgeon,
_Annals_, Vol. VIII. p. 363; also note at p. 491 of Ronalds’
“Catalogue”; _Mém. de l’Acad. de Berlin_, “Théorie Générale du
Plaisir”; also “Temple du Bonheur,” published at Bouillon (Pays
Bas), 1769, Tome III. p. 124, this last-named work being alluded
to in the _Journal des Débats_, 7 Vendémiaire, au X; Edm. Hoppe,
“Geschichte,” 1884, p. 128; C. H. Wilkinson, “Elements of
Galvanism,” Vol. I. p. 69, note; Albert’s “Amer. Ann. d. Artz,”
Vol. II. Bremen, 1802.

=A.D. 1762.=--Ledru Comus, French Professor of Natural Philosophy, invents a mode of telegraphing which is described and fully illustrated in Vol. I of Guyot’s “Nouvelles Récréations Physiques et Mathématiques,” Paris, 1769; as well as at p. 278 of “Mémoires, Correspondance et Ouvrages Inédits de Diderot,” Paris, 1821, in one of the letters to Mlle. Voland dated July 28, 1762.

His apparatus consisted of two dials, each bearing upon it twenty-five letters of the alphabet, which were moved by the agency of magnets and of magnetized needles; but Auguste Guérout considers the contrivance to have been merely a speculative one, as will be seen by his article, reproduced from “La Lumière Electrique” of March 3, 1883, in No. 384 of the “Scientific American Supplement.”

REFERENCES.--_Journal de Physique_ for 1775, Vols. V and VI;
for 1776, Vol. VII; and for 1778, Vol. I; “Scelta di Opuscoli,”
Milano, 1776.

=A.D. 1765.=--Cigna (Giovanni Francesco), native of Mondovi, Italy, and nephew to the electrician Beccaria (A.D. 1753), became secretary to the society of savants who gave birth to the Royal Academy of Sciences at Turin, and whose Memoirs contain his work, “De novis quibusdam experimentis electricis,” 1765.

At pp. 31–65 of the above Memoirs is given a full account of Cigna’s many curious observations made with silk ribbons placed in various positions, and in contact with different surfaces, instead of with the silk stockings employed by Symmer (A.D. 1759). He thus supplies the main defect of Dufay’s theory (A.D. 1733) by proving that the two opposite electricities are produced simultaneously. On p. 47 of the same work will be found a report of Cigna’s experiment with ice to ascertain whether electric substances contain more electric matter than other bodies.

REFERENCES.--Vol. III. p. 168 of Nollet’s “Letters,” for an
account of his observations upon the electric attraction and
repulsion between conducting substances immersed in oil; as well
as Chap. II. s. 3., vol. i. of Van Swinden’s “Receuil,” etc.,
published at La Haye, 1784. Should also be consulted: Cigna’s
“Memoirs on Electricity and Magnetism” in the “Miscellanea
... Taurinensia,” and the several communications made by him
to Priestley, Lagrange and others in 1775 concerning Volta’s
electrophorus; likewise “Memorie istorische ... di Gianfrancesco
Cigna de Antonmaria Vassalli Eandi,” Torino, 1821.

=A.D. 1766–1776.=--Lambert (Johann Heinrich), a profound German mathematician, native of Upper Alsace, publishes in Vol. XXII of the “Reports of the Berlin Academy” two beautiful Memoirs upon the “Laws of Magnetic Force” and upon the “Curvature of the Magnetic Current,” both of which, according to Dr. Robison, would have done credit to Newton himself.

In the first Memoir, says Harris, the author endeavours to determine two very important laws; one relating to the change of force as depending upon the obliquity of its application, the other as referred to the distance. In the second Memoir the curves of the magnetic current are investigated by the action of the directive or polar force of a magnet upon a small needle. Lambert concludes that the effect of each particle of the magnet on each particle of the needle, and reciprocally, is as the absolute force or magnetic intensity of the particles directly, and as the squares of the distances inversely.

Noad states (“Manual,” London, 1859, p. 580) that Lambert’s deductions were confirmed twenty years later by Coulomb, through the agency of his delicate torsion balance, and more recently (about the year 1817) by Prof. Hansteen, of Christiania.

Previous to the above-named date, in 1760, Lambert had published, both at Leipzig and at Augsburg, his “Photometria, sive de Mensura et Gradibus Luminis, Colorum et Umbræ,” the sequel to a tract printed two years before, wherein he indicates the mode of measuring the intensity of the light of various bodies. The celebrated mathematician and astronomer, Pierre Bouguer (1698–1758), who had published, in 1729, his “Essai d’Optique,” etc., which was greatly enlarged in his “Traité,” etc., brought out by La Caille in 1760, may be considered the founder of this branch of the science of optics, to which the name _photometry_ has been given by English writers. The photometer designed by Sir Benjamin Thompson, _Count Rumford_ (entered at A.D. 1802), has been described in _Phil. Trans._ for 1794, Vol. LXVII. His method is to cast two shadows of a given object near each other on the same surface, the lights being removed to such distances that the shadows appear equally dark.

REFERENCES.--Sir John Leslie’s “Fifth Dissertation” in the
eighth “Encycl. Brit.”; Count Rumford’s photometer illustrated
at Plate XXVII. figs. 387, 388, vol. i. of Dr. Thomas Young’s
“Course of Lectures,” London, 1807; also Vol. II. pp. 282 and
351 of the same work, concerning photometry generally; Dredge
and others, “Electric Illumination,” etc. (chiefly compiled from
London _Engineering_), Vol. II. pp. 101–117; Brewster’s “Edin.
Jour. of Sc.,” 1826, Vol. II. p. 321; Vol. III. p. 104; Vol.
V. p. 139, for William Ritchie’s articles on the photometer of
Mr. Leslie, and relative to an improved instrument upon the
principles of Bouguer (_Edin. Transactions_, Vol. X. part. ii.);
Lambert’s biography and the article “Magnetism” in the “Encycl.
Brit.”; Harris, “Rudim. Magn.,” Part III. pp. 20, 33, 191–203.

It may be added that all the valuable manuscripts left by Lambert were purchased by the Berlin Academy, and were afterward published by John Bernoulli, a grandson of the celebrated John Bernoulli alluded to at A.D. 1700.

=A.D. 1766.=--Lullin (Amadeus), in his “Dissertatio physica de electricitate,” Geneva, 1766, at p. 26, alludes to Beccaria’s experiments, saying that he produced much greater effects with the electric spark by passing the latter through oil instead of water: oil being a much worse conductor, the spark in it is larger. At p. 38 of the same work he details the experiments made to prove the correctness of Mollet’s doctrine regarding the constant motion of electrical atmospheres, and at p. 42 are given his experiments to show the production of electricity in the clouds. With a long insulated pole projecting from the mountain side he observed, among other effects, that when small clouds of vapour produced by the sun’s heat touched only the end of the pole the latter was electrified, but that it was not affected if the entire pole was covered by the vapour (“Lib. Useful Knowledge,” “Electricity,” Chap. XI. Nos. 154, etc.).

Lullin, it is said, proposed a modification of Reusser’s plan of telegraphing, in manner stated at p. 69 of Reid’s 1887 “Telegraph in America.”

=A.D. 1766.=--L’Abbé Poncelet, a native of Verdun, France, publishes at Paris “La Nature dans la formation du Tonnerre,” etc., wherein he indicates a method of protecting from lightning residences, pavilions and other structures, by constructing them of resinous woods and lining them with either silk or waxed cloths. He quaintly remarks that as they thus present “on all sides resinous surfaces, which never receive phlogiston by communication, the latter (thunder and lightning), after having leaped lightly around the pavilion and finding itself unable to attack it, will probably depart in order to pursue its ravages elsewhere.”

REFERENCES.--_Scientific American Supplement_, No. 66, p. 1053,
for a copy of the frontispiece of the above-named work; also
Figuier, “Exposition et Histoire,” etc., 1857, Vol. IV. pp. 234,
235.

=A.D. 1767.=--Bozolus (Joseph), an Italian Jesuit, Professor of Natural Philosophy at Rome, is the first (and not Cavallo, A.D. 1775) to suggest employing the active principle of the Leyden jar for the transmission of intelligence.

His plan is to place underground two wires which are to be brought at each station close enough to admit of the passage of a spark. One of the wires is to be connected with the inner coating and the other with the outer surface of a Leyden phial; the sparks observed at the opening between the wires being there made to express any meaning according to a preconcerted code of signals.

REFERENCES.--Latin poem entitled “Mariani Parthenii
Electricorum,” in six books, Roma, 1767, lib. i. p. 34
(describing the _telegrafo elettrico scintillante_); also
_Saturday Review_, August 21, 1858, p. 190, and _Cornhill
Magazine_ for 1860, Vol. II. p. 66.

=A.D. 1767.=--Priestley (Joseph), the earliest historian of electrical science, publishes, by advice of Benjamin Franklin, the first edition of his great work, “The History and Present State of Electricity,” of which there were four other separate enlarged issues, in 1769, 1775, 1775 and 1794. During the year 1766 he had been given the degree of Doctor of Laws by the Edinburgh University and he had also, at the instance of Franklin, Watson and others, been made a member of the English Royal Society, which, a few years later, bestowed upon him the Copley medal.

Speaking of the above-named work, Dr. Lardner says (“Lectures, 1859, Vol. I. p. 136): “This philosopher did not contribute materially to the advancement of the science by the development of any new facts; but in his ‘History of Electricity’ he collected and arranged much useful information respecting the progress of the science.” Nevertheless, to him is due the first employment of the conductor supported by an insulating pillar, as described by Noad, who gives an account of Priestley’s electrical machine at Chap. IV of his “Manual”; and he is also the first to investigate upon an extensive scale the chemical effects of ordinary electricity. The observations of M. Warltire, a lecturer on natural philosophy, and Priestley’s own experiments in this line, made by passing the electric spark through water tinged blue by litmus, also through olive oil, turpentine, etc., as well as his researches more particularly upon the gases and upon the influence of the electric fluid in expanding solid bodies, are detailed at the “Electricity” chapter of the “Encycl. Brit.”

At pp. 660–665 of the fourth edition of his “History,” Priestley describes the experiments he made to illustrate what he called the _lateral force of electrical explosions_; that is, the tendency of the fluid to diverge, as is the case with lightning when any material obstruction lies in its path.

Perhaps the most important of all Dr. Priestley’s electrical discoveries (Thomson, “Hist. Roy. Soc.,” p. 445) was that charcoal is a conductor of electricity, and so good a conductor that it vies even with the metals themselves. When the conducting power of charcoal was tried by succeeding electricians, it was found to vary in the most unaccountable manner, sometimes scarcely conducting at all, sometimes imperfectly and sometimes remarkably well; a diversity naturally indicating some difference in the nature of the different specimens of English charcoal (Priestley’s “History,” etc., Part VIII. s. 3). Charcoal being examined by Mr. Kinnersley (at A.D. 1761), was also by him observed to vary in its conducting power. Oak, beech and maple charcoal he found to conduct satisfactorily; the charcoal from the pine would not conduct at all, while a line drawn upon paper by a heavy black lead pencil conducted pretty well (_Phil. Trans._, 1773, Vol. LXIII. p. 38).

REFERENCES.--Priestley’s letter to Dr. Franklin (_Phil. Trans._,
Vol. LXII. p. 360) concerning William Henley’s new electrometer
and experiments; likewise the _Phil. Trans._, Vol. LVIII. p. 68;
Vol. LIX. pp. 57, 63; Vol. LX. p. 192; Vol. LXII. p. 359; and
the abridgments by Hutton, Vol. XII. pp. 510, 600, 603; Vol.
XIII. p. 36; “Trans. of the Amer. Phil. Soc.,” O. S., Vol. VI.
part i. p. 190, containing proceedings of the Society on the
death of Joseph Priestley; Wilkinson’s “Elements of Galvanism,”
etc., London, 1804, Vol. II. pp. 74–80; Noad’s Lectures, No. 4,
Knight’s edition, pp. 182, 183; “Library of Useful Knowledge,”
London, 1829, Chap. “Electricity,” pp. 41 and 45; “Library of
Literary Criticism,” C. W. Moulton, Buffalo, 1901–1902, Vol. IV.
pp. 444–456; “Essays, Reviews and Addresses” by James Martineau,
London, 1890, Vol. I. pp. 1–42; “Mém. de l’Institut” (Histoire),
Tome VI. 1806, p. 29 for Elogium; “Essays in Historical
Chemistry,” T. E. Thorpe, London, 1894, pp. 28, 110; “Science
and Education,” by Thos. Henry Huxley, New York, 1894, pp. 1–37;
“Scientific Correspondence of Jos. Priestley,” by H. C. Bolton,
New York, 1902; Dr. Thos. H. Huxley, “Science Culture,” 1882, p.
102; Warltire, in Muirhead’s translation of Arago’s “Eloge de
James Watt,” pp. 99, 100; also the appendix to the last-named
work, p. 157 and note.

=A.D. 1767.=--Lane (Thomas--Timothy), a medical practitioner of London, introduces his _discharging electrometer_, which is now to be found described and illustrated in nearly all works on electricity.

It consists of a bent glass arm, one end of which is attached to a socket in the wire of the Leyden jar, while the other end holds a horizontal sliding brass rod, or spring tube, which bears a ball at each extremity. The rod is usually divided into inches and tenths, indicating the force of the discharge which takes place when the knob of the jar is placed in contact with the prime conductor of an electrical machine, and the charge is strong enough to leap from one to the other. In Mr. Lane’s experiments the shocks were twice as frequent when the interval between the balls was one twenty-fourth of an inch as when twice as much: from which he concluded that the quantity of electricity required for a discharge is in exact proportion to the distance between the surfaces of the balls.

A combination of the Lane and other electrometers was made by Mr. Cuthbertson, as shown at p. 528, Vol. II of _Nicholson’s Journal of Natural Philosophy_, and at p. 451, Vol. LVII of the _Philosophical Transactions_.

REFERENCES.--_Phil. Trans._ for 1805; Hutton’s abridgments, Vol.
XII; p. 475; Cavallo, “Elements ... Phil.” 1825, Vol. II. p 197;
Harris, “Electricity,” p. 103; _Monthly Magazine_, December
1805, and _Tilloch’s Philosophical Magazine_, Vol. XXIII. p. 253.

The Hutton abridgments contain, at p. 308, Vol. XV, the description of a new electrometer by Abraham Brook.

=A.D. 1768.=--Ramsden (Jesse), a very capable English manufacturer of mechanical instruments, member of the Royal Society and of the Imperial Academy of St. Petersburg, is said to be the first to construct an electrical machine wherein a plate of glass is substituted for the glass globe of Newton and of Hauksbee and for the glass cylinder of Gordon (at A.D. 1675, 1705 and 1742). The same claim which has been made for Martin de Planta, Swiss natural philosopher, appears to have no foundation. (See note at p. 401 of Ronalds’ “Catalogue.”)

REFERENCES.--_Journal des Sçavans_, November 1788, p. 744;
_Phil. Trans._, 1783; “Chambers’ Encyclopædia,” 1868, Vol. III.
p. 812; Mme. Le Breton, “Hist. et app. de l’Electricité,” Paris,
1884, pp. 61, 62.

=A.D. 1768.=--Molenier (Jacob), physician to the French King, Louis XV, writes “Essai sur le Mécanisme de l’Electricité” for the purpose of showing the utility of the application of the electric fluid in medical practice. At p. 60 he explains the effects and results when applications are made more particularly to the nerves, and at pp. 65–67 he gives certificates of many of the cures he has effected of gout, rheumatism, tumours, cancers, loss of blood, as well as of pains and aches of various descriptions.