Chapter XXIII: Book I: chap. i. Therein, he says that Baptista Porta, who has made the (8)

REFERENCES.--Arago, “Eloge Historique de Volta” and “Notices
Biographiques,” Tome I. p. 234 (“Raccolta Pratica di Scienze,”
etc. for March and April 1835); London _Times_ of January 26,
1860; the eulogies pronounced by Giorn. Fogliani at Como and
by G. Zuccala at Bergamo, the year of Volta’s death, 1827; P.
Sue, “Histoire du Galvanisme,” Tome II. p. 267; _Journal de
Leipzig_, Tome XXXIV; _Scelta d’ Opuscoli_, Vols. VIII. p.
127; IX. p. 91; X. p. 87; XII. p. 94; XIV. p. 84; XXVIII. p.
43; XXXIV. p. 65; _Opuscoli Scelti_, Vols. I. pp. 273, 289;
VII. pp. 128, 145; XV. pp. 213, 425; XXI. p. 373; “Mem. dell’
I. R. Istit. Reg. L. V.,” Vol. I. p. 24; “Mem. dell’ Istit.
Nazion. Ital.,” Vol. I. p. 125; “Memor. Soc. Ital.,” Vols. II.,
pp. 662, 900; V. p. 551; “Bibl. Fisica d’Europa” for 1788;
“Giornale Fis.-Med.,” Vols. I. p. 66; II. pp. 122, 146, 241,
287; III. p. 35; IV. p. 192; V. p. 63; “Giornale dell’ Ital.
Lettera,” etc., Vol. VIII. p. 249; L. V. Brugnatelli, “Annali
di Chimica,” etc., Vols. II. p. 161; III. p. 36; V. p. 132;
XI. p. 84; XIII. p. 226; XIV. pp. 3, 40; XVI. pp. 3, 27, 42;
XVIII. pp. 3, 7; XIX. p. 38; XXI. pp. 79, 100, 163; XXII. pp.
223–249 (Aless. Volta and Pietro Configliachi); Aless. Volta
and Angelo Bellani, “Sulla formazione,” etc., Milano, 1824; F.
A. C. Gren, _Neues Journal der Physik_, Vols. III and IV for
1796 and 1797; Rozier, _Observ._, Vols. VII, XXII and XXIII for
1776, 1873; J. B. Van Mons, _Journal de Chimie_, No. 2, pp. 129,
167; Sédillot, “Receuil Per. de la Soc. de Méd. de Paris,” IX.
pp. 97, 231; _Journal de Phys._, Vols. XXIII. p. 98; XLVIII.
p. 336; LI. p. 334; LXIX. p. 343; _Annales de Chimie_, Vols.
XXX. p. 276; XLIV. p. 396; _Nicholson’s Journal_, Vol. XV. p.
3; _Phil. Tr._ for 1778, 1782 and 1793; “Soc. Philom.,” An.
IX. p. 48, An. X. p. 74; “Bibl. Brit.,” Vol. XIX. p. 274; _Le
Correspondant_ for August, 1867, p. 1059, and _Les Mondes_,
December 5, 1867, p. 561; Highton, “The Elec. Tel.,” 1852,
pp. 13 and 28; Robertson, “Mémoires Récréatifs,” 1840, Vol.
I. chaps, x. and xiii.; Miller, “Hist. Philos. Illustrated,”
London, 1849, Vol. IV. p. 333, note; Achille Cazin, “Traité
théorique et pratique des piles électriques,” Paris, 1881;
“Mémoires de l’lnstitut” (Hist.) An. XII. p. 195; Andrew Crosse,
“Experiments in Voltaic Electricity,” London, 1815 (_Phil.
Mag._, Vol. XLVI. p. 421, and Gilbert’s “Annalen,” Bd. s. 60);
“Lettere sulla Meteorol.,” 1783; Theod. A. Von Heller, in Gilb.
“Annal.,” Vols. IV and VI, 1800; and _Gren’s Neues Journ._,
1795, 1797; “L’Arc Voltaique,” by M. Paul Janet, in “Revue
Générale des Sciences,” May 15, 1902, pp. 416–422; “L’Académie
des Sciences,” par Ernest Maindron, Paris, 1888, pp. 245–251;
“Philosophical Magazine,” Vol. IV. pp. 59, 163, 306; Vol. XIII.
pp. 187–190 [_re_ prize founded by Napoleon); Vol. XXI. p. 289
(electrophorus); Vol. XXVIII. p. 182 (theory of Pierre Hyacinthe
Azais), and p. 297 (Paul Erman on “Voltaic Phenomena”); Thomson,
“Hist. of Chemistry,” Vol. II. pp. 251–252; “Dict. de Gehler,”
Vols. III. p. 665; VI. pp. 475, 484; Thomas Thomson, “Hist. of
the Royal Soc.,” London, 1812, p. 451; Young’s “Lectures,”
Vol. I. pp. 674, 677, 678, 683; see likewise the “Theory of
the Action of the Galvanic Pile,” as given by Dr. Wm. Henry
at s. 5 Vol. I. of his “Elements of Experimental Chemistry,”
London, 1823; also _Nicholson’s Journal_ for Henry’s essay in
Vol. XXXV. p. 259; M. De Luc’s papers in Vol. XXXII. p. 271,
and Vol. XXXVI. p. 97; Mr. Singer on the “Electric Column” in
Vol. XXXVI. p. 373; Dr. Bostock’s essay in Thomson’s “Annals,”
Vol. III. p. 32; Sir H. Davy’s chapter on “Electrical Attraction
and Repulsion,” in his “Elements of Chem. Philos.,” p. 125;
the first volume of Gay-Lussac and Thénard’s “Recherches”;
Johann Mayer, “Abhandlungen ... Galvani, Valli, Carminati u.
Volta,” etc., Prague, 1793; _Lehrbuch der Meteor._, von L. F.
Kaemtz, Halle, 1832, Vol. II. pp. 398, 400, 418; M. Detienne
et M. Rouland in _Jour. de Phys._, Vol. VII. for 1776; J.
N. Hallé, “Exposition Abrégée,” etc. (“Bull. des Sc. de la
Soc. Philom.,” An. X. No. 58); C. B. Désormes’ very extended
observations recorded in the _An. de Ch._, Vol. XXXVII. p. 284;
Volta’s letter to Prof. F. A. C. Gren in 1794, and Wilkinson,
“El. of Galv.,” Vol. II. pp. 314–325; J. F. Ackerman (“Salz.
Mediechirurg,” 1792, p. 287); Cadet (_An. de Ch._, Vol. XXXVII.
p. 68); letter written by Volta to M. Dolomieu (“Bull. de la
Société Philom.,” No. 55, p. 48); Friedlander’s “Experiments”
(_Jour. de Phys._, Pluvoise, An. IX. p. 101); Paul Erman (_Jour.
de Phys._, Thermidor, An. IX. p. 121); Gilbert’s “Annalen,”
VIII, X, XI, XIV); _Jour. de Phys._, Tome LIII p. 309; _Jour. de
Médecine_, Nivose, An. IX. p. 351; P. C. Abilgaard,“Tentamina
Electrica”; C. H. Wilkinson, “Elements of Galvanism,” etc.,
London, 1804, 2 vols. _passim_; A. W. Von Hauch’s Memoir read
before the Copenhagen Acad. of Sc. (Sue, “Hist. du Galv.,” 1802,
Vol. II. p. 255); Alexander Nicoläus Scherer’s Journal, 31st
book; “Abstracts of Papers of Roy. Soc.,” Vol. I. p. 27; also
Hutton’s abridgments of the _Phil. Trans._ Vol. XV. p. 263;
Vol. XVII. p. 285; Vol. XVIII. pp. 744, 798; _Phil. Magazine_,
Vol. IV. pp. 59, 163, 306; “Bibliothèque Britannique,” Genève,
1796, Vol. XV. an. viii. p. 3; Vol. XIX for 1802, pp. 270,
274, 339; Vol. XVI, N.S. for 1821, pp. 270–309; account of the
immense electrophorus constructed for the Empress of Russia, in
Vol. I. of “Acta Petropolitana” for 1777, pp. 154, etc. In the
_Philosophical Transactions_ for 1778, pp. 1027, 1049, will be
found Ingen-housz’s paper relating to the then recent invention
of Volta’s _electrophorus_ and to Mr. Henley’s experiments. It
is said that at about this time (1778), John Jacob Mumenthaler,
Swiss mechanic, constructed very effective electrophori and
electric machines out of a very peculiar kind of paper. M. F.
Vilette also made a paper electrophorus which is alluded to by
J. A. Nollet (“Experiments Letters,” Vol. III. pp. 209, etc.).
Consult, besides, Carlo Barletti, “Lettera al Volta ...” Milano,
1776; W. L. Krafft, “Tentatem theoriæ ...” Petropol, 1778; J. C.
Schäffer, “Abbild. Beschr. d. elek. ...” Regensberg, 1778; Georg
Pickel, “Experimenta physico-medica ...” Viceburgi, 1778–1788;
J. A. Klindworth, “Kurze Beschr. ...” Gotha, 1781–1785;
(Lichtenberg’s “Magazin,” I. 35–45;) while for Klindworth, M.
Obert and M. Minkeler, see the “Goth. Mag.,” I. ii. p. 35; V.
iii. pp. 96, 110; E. G. Robertson, “Sur l’électrophore résineux
et papiracé,” Paris, 1790; (_Journal de Physique_, Vol. XXXVII;)
M. Robert on the electrophorus (Rozier, XXXVII. p. 183); S.
Woods, “Essay on the phenomena ...” London, 1805; (_Phil. Mag._,
Vol. XXI. p. 289;) M. Eynard’s “Mém. sur l’electrophore,” Lyon,
1804; John Phillips, “On a modification of the electrophorus,”
London, 1833 (_Phil. Mag._, s. 3, Vol. II); G. Zamboni, “Sulla
teoria ...” Verona, 1844 (“Mem. Soc. Ital.,” Vol. XXIII); F. A.
Petrina, “Neue theorie d. elect. ...” Prag., 1846.

=A.D. 1776.=--Borda (Jean Charles), French mathematician and astronomer, improves upon the work of Mallet (at A.D. 1769), and is the first to establish accurately the knowledge of the third and most important element of terrestrial magnetism, viz. its _intensity_.

To him is exclusively due the correct determination of the difference of the intensity at different points of the earth’s surface by measuring the vibrations of a vertical needle in the magnetic meridian. This he determined during his expedition to the Canary Islands, and his observations were first confirmed through additional experiments which the companion of the unfortunate La Pérouse, Paul de Lammanon, made during the years 1785–1787, and which were by him communicated from Macao to the Secretary of the French Academy.

REFERENCES.--Borda’s biography in the “Eng. Cycl.,” and in the
eighth “Britannica”; Walker, “Magnetism,” p. 182; Humboldt
on magnetic poles and magnetic intensity, embracing the
observations of Admiral de Rossel, and “Cosmos,” Vol. V. 1859,
pp. 58, 61–64, 87–100; also Vol. I. pp. 185–187, notes, for the
history of the discovery of the law that the intensity of the
force increases with the latitude; Norman (A.D. 1576).

=A.D. 1777.=--Lichtenberg (Georg Christoph), Professor of Experimental Philosophy at the University of Göttingen, reveals the condition of electrified surfaces by dusting them with powder.

The _figures_, which bear his name, are produced by tracing any desired lines upon a cake of resin with the knob of a Leyden jar and by dusting upon the cake a well-triturated mixture of sulphur and of red lead. These substances having been brought by friction into opposite electrical conditions, the sulphur collects upon the positive and the lead upon the negative portions of the cake: positive electricity producing an appearance resembling feathers, and negative electricity an arrangement more like stars.

REFERENCES.--Harris, “Frict. Elect.,” p. 89; eighth
“Britannica,” Vol. VIII. p. 606; E. Reitlinger, “Sibven Abh.
...” (Wien Acad.); illustrations in _Sc. Am. Suppl._, No. 207,
p. 3297; Noad, “Manual,” p. 132; Erxleben’s “Physikalische
Bibliotek,” s. 514; L. F. F. Crell, _Chemische Annalen_ for
1786; “Göttingisches Magazin,” J i., S ii., pp. 216–220;
Lichtenberg’s “Math. u. Phys. Schriften,” etc., Vol. I. p. 478.
See also Dr. Young’s “Lectures on Nat. Phil.,” London, 1807,
Vol. II. pp. 119, 419 for additional references, and p. 426 for
Lichtenberg’s “Table of Excitation.”

=A.D. 1777.=--Pringle (Sir John), a man of great scientific attainments--who was physician to the Duke of Cumberland as well as to the Queen’s household, became a baronet in 1766, and afterward received many distinguished honours from foreign learned bodies--resigns the Presidency of the English Royal Society, which he had held since the year 1772. In this, as will be seen at a later date, he was succeeded by Sir Joseph Banks (at A.D. 1820), who continued in the office a period of over forty-two years. The cause which led to his resignation is best given in the following extract from his biography in the English Cyclopedia:

“During the year 1777 a dispute arose among the members of the Royal Society relative to the form which should be given to electrical conductors so as to render them most efficacious in protecting buildings from the destructive effects of lightning. Franklin had previously recommended the use of points, and the propriety of this recommendation had been acknowledged and sanctioned by the Society at large. But, after the breaking out of the American Revolution, Franklin was no longer regarded by many of the members in any other light than an enemy of England, and, as such, it appears to have been repugnant to their feelings to act otherwise than in disparagement of his scientific discoveries. Among this number was their patron George III, who, according to a story current at the time, and of the substantial truth of which there is no doubt, on its being proposed to substitute knobs instead of points, requested that Sir John Pringle would likewise advocate their introduction. The latter hinted that the laws and operations of nature could not be reversed at royal pleasure; whereupon it was intimated to him that a President of the Royal Society entertaining such an opinion ought to resign, and he resigned accordingly.”

In Benjamin Franklin’s letter to Dr. Ingen-housz, dated Passy, Oct. 14, 1777, occurs the following: “The King’s changing his _pointed_ conductors for _blunt_ ones is therefore a matter of small importance to me. If I had a wish about it, it would be that he had rejected them altogether as ineffectual.” It was shortly after the occurrence above alluded to that the following epigram was written by a friend of Dr. Franklin:

“While you Great George, for knowledge hunt,
And sharp conductors change for blunt,
The nation’s out of joint:
Franklin a wiser course pursues,
And all your thunder useless views,
By keeping to the _point_.”

Thomson informs us (“Hist. Roy. Soc.” pp. 446–447) that the Board of Ordnance having consulted the Royal Society about the best mode of securing the powder magazine, at Purfleet, from the effects of lightning, the Society appointed Mr. Cavendish, Dr. Watson, Dr. Franklin, Mr. Robertson and Mr. Wilson a committee to examine the building and report upon it. These gentlemen went accordingly, and the first four recommended the erecting of pointed conductors in particular parts of the building, as a means which they thought would afford complete security. Mr. Wilson dissented from the other gentlemen, being of the opinion that the conductors ought not to be pointed but blunt, because pointed conductors solicit and draw down the lightning which might otherwise pass by. He published a long paper on the subject, assigning a great variety of reasons for his preference (_Philosophical Transactions_, Vol. LXIII. p. 49). It was this dissent of Mr. Wilson which produced between the electricians of the Royal Society a controversy respecting the comparative merits of pointed and blunt conductors, which continued a number of years, and a variety of papers in support of which made their appearance in the _Philosophical Transactions_. The controversy, in fact, engaged almost the exclusive attention of the writers on electricity for several successive volumes of that work.

REFERENCES.--William Henley, “Experiments ... pointed and
blunted rods ...” in _Phil. Trans_, for 1774, p. 133; P. D.
Viegeron, “Mémoire sur la force des pointes ...”; Edward Nairne,
“Experiments ... advantage of elevated pointed conductors,” in
_Phil. Trans._ for 1778, p. 823; Lord Mahon, “Principles ...
superior advantages of high and pointed conductors,” London,
1779; Hale’s “Franklin in France,” 1880, Part I. p. 91, and