Chapter XXIV: Part II: pp. 254–256, 279, for some of his other correspondence (1)

with Dr. Ingen-housz; likewise Part II., pp. ix, 273, 441–451,
regarding the first publication of copies of letters written
by Franklin to Sir Joseph Banks, which “for some curious
reason,” Mr. Hale remarks, were not publicly read and were
never included in the _Philosophical Transactions_, as Franklin
intended they should be. Consult also Thomas Hopkinson on “The
Effects of Points,” etc., in Franklin’s “New Experiments,”
etc., London, 1754; Tilloch’s _Philosophical Magazine_ for
1820; Hutton’s abridgments, Vol. XIII. p. 382; “Memoir of Sir
J. Pringle” in Weld’s “Hist. of Roy. Soc.,” Vol. II. pp. 58–67,
102; Jared Sparks’ edition of Franklin’s “Works,” and Sir John
Pringle’s discourse delivered at the Anniversary Meeting of
the Royal Society, Nov. 30, 1774, a translation of the last
named appearing at p. 15, Vol. XV of the “Scelta d’ Opuscoli.”
J. Clerk Maxwell, “Electrical Researches of the Hon. Henry
Cavendish,” 1879, pp. 52–54.

=A.D. 1778.=--Martin (Benjamin), English artist and mathematician, who had already written an “Essay on Electricity” and a prominent supplement thereto (1746–1748), publishes an enlarged edition in three volumes of his “Philosophia Britannica,” originally produced in 1759. At Vol. I. p. 47 of the last-named work, he states that his experiments indicate a magnetic force inversely as the square roots of the cubes of the distances. Noad, treating of the laws of magnetic force, says (“Electricity” p. 579) that Martin and Tobias Mayer both came to the conclusion that the true law of the magnetic force is identical with that of gravitation, and that, in the previous experiments of Hauksbee and others, proper allowance had not been made for the disturbing changes in the magnetic forces so inseparable from the nature of the experiments.

His first Lecture explains all the phenomena of electricity and magnetism, the appendix thereto detailing numerous experiments of Mr. John Canton, and giving many additional facts concerning the manufacture of artificial magnets. From his preface the following extracts will, doubtless, prove interesting: “We are arrived at great dexterity since Sir Isaac Newton’s time; for we can now almost prove the existence of this _aether_ by the phenomena of electricity; and then we find it very easy to prove that electricity is nothing but this very _aether_ condensed and made to shine. But I believe, when we inquire into the nature and properties of this _aether_ and electricity, we shall find them so very different and dissimilar, that we cannot easily conceive how they should thus mutually prove each other.... I see no cause to believe that the matter of electricity is anything like the idea we ought to have of the _spiritus subtilissimus_ of Sir Isaac.... The smell also of _electrical fire_ is so very much like that of _phosphorus_, that we may be easily induced to believe a great part of the composition of both is the same.”

REFERENCES.--“Encycl. Britan.,” 1857, Vol. XIV. p. 320; Antoine
Rivoire (Rivière), “Traité sur les aimants ...” Paris, 1752;
Nicolaus von Fuss, “Observations ... aimants ...” Petersburg,
1778; Le Noble, “Aimants artificiels ...” Paris, 1772, and
“Rapport ... aimants,” 1783 (Mém. de Paris); Wens, “Act. Hill,”
Vol. II. p. 264; C. G. Sjoestén (Gilbert, _Annalen der Physik_,
Vol. XVII. p. 325); Rozier, IX. p. 454.

=A.D. 1778.=--Toaldo (Giuseppe) Abbé, celebrated Italian physicist, who had in 1762 been made Professor at the Padua University and was the first one to introduce the lightning rod in the Venetian States, makes known the merits of the last-named invention through his “Dei conduttori per preservare gli edifizj,” etc., which work embraces most of his previous treatises on metallic conductors as well as the translation of H. B. de Saussure’s “Exposition abrégée,” etc., Geneva, 1771, and of M. Barbier de Tinan’s “Considérations sur les conducteurs en général.”

The above was followed by many highly interesting memoirs containing valuable meteorological observations, notably those in continuation of the work of J. Poleni, made close up to the time of Toaldo’s sudden death at Padua, Dec. 11, 1798. His complete works, covering the period 1773–1798, were published in Venice through M. Tiato, with the assistance of Vincenzo Chiminello, during the year 1802.

REFERENCES.--In addition to the last-named publication (entitled
“Completa Raccolta d’ Opuscoli,” etc.), “Mem. della Soc. Ital.,”
Vol. VIII. pt. i. p. 29 (“Elogio ... da A. Fabbroni,” 1799);
note at Beccaria, p. 42 of Ronalds’ “Catalogue”; Larousse,
“Dict. Universel,” Vol. XV. p. 251; “Biographie Générale,” Vol.
XLV. p. 450; “Biografia degli Italiani Illustri,” etc., by
E. A. Tipaldo, Vol. VIII; “Padua Accad. Saggi,” Vol. III. p.
cv; “Opusc. Scelti,” Vol. VI. p. 265; Vol. VII. p. 35; “Nuovo
Giornale Enciclopedico di Vicenza” for 1784; Antonio Maria
Lorgna, “Lettera ... parafulmini,” 1778; G. Marzari (Vol. II.
p. 73, of “Treviso Athenæum”); Fonda “Sopra la maniera ...”
Roma, 1770; G. Marzari e G. Toaldo, “Memoria Descrizione ...”
25 Aprile, 1786; Barbier de Tinan, “Mémoire sur la manière
d’armer,” etc., Strasbourg, 1780; F. Maggiotto’s letter to
Toaldo upon a new electrical machine; Sestier et Méhu, “De la
foudre,” etc., Paris, 1866.

Vincenzo Chiminello, nephew of Giuseppe Toaldo, whom he succeeded at the Padua Observatory and who continued the _Giornale Astro-meteorologico_ after his uncle’s death, is the author of works on the magnetic needle, on lightning conductors, etc., which are treated of in the columns of the _Mem. Soc. Ital._, Vols. VII and IX; the _Giornale Astro-met._ for 1801, 1804, 1806, as well as in the _Saggi ... dell’Accad. di Padova_, _Nuova Scelta d’Opuscoli_, and _Opuscoli Scelti sulle scienze e sulle arti_.

REFERENCES.--Chiminello’s biography, _Giorn. dell’Ital.
Lettera_, etc., Serie II. tome xvii. p. 164, and in “Atti della
Soc. Ital.,” Modena, 1819.

=A.D. 1778.=--Dupuis (Charles François), eminent French writer who, at the age of twenty-four, became Professor of Rhetoric at the College of Lisieux, constructs a telegraph upon the plan suggested by Amontons (at A.D. 1704). By means of this apparatus he exchanged correspondence with his friend M. Fortin, then residing at Bagneux, until the commencement of the Revolution, when he deemed it prudent to lay it permanently aside (_Encyclopædia Britannica_, 1855, Vol. VIII. p. 263).

=A.D. 1778.=--Brugmans--Brugman (Anton), who was Professor of Philosophy at the University of Francker between 1755 and 1766, publishes his “Magnetismus, seu de affinitatibus magneticis.” He is, besides, the author of several works upon magnetic matter and the magnetic influence, which appeared 1765–1784 and are alluded to by Poggendorff (“Biog.-Liter. Hand.,” Vol. I. p. 316), as well as in the “Vaderlandsche Letter” for 1775 and 1776, and at p. 34, Vol. I of Van Swinden’s “Recueil de Mémoires ...” La Haye, 1784.

It was in this same year, 1778, that Sebald Justin Brugmans--Brugman--son of Anton Brugmans, a distinguished physician, naturalist and author who was the successor of Van Swinden at the Francker University, and became Professor of Botany at Leyden, discovered that cobalt is attracted while bismuth and antimony are repelled by the single pole of a magnet, thus laying _the foundation of the science of diamagnetism_.

Humboldt remarks: “Brugmans, and, after him, Coulomb, who was endowed with higher mathematical powers, entered profoundly into the nature of terrestrial magnetism. Their ingenious physical experiments embraced the magnetic attraction of all matter, the local distribution of force in a magnetic rod of a given form, and the law of its action at a distance. In order to obtain accurate results the vibrations of a horizontal needle suspended by a thread, as well as deflections by a torsion balance, were in turn employed.”

REFERENCES.--“Biographie Générale,” Vol. VII. p. 582; Larousse,
“Dict. Univ.,” Vol. II. p. 1334; “Catalogue Sc. Papers Roy.
Soc.,” Vol. I. p. 672; W. H. Wollaston, “Magnetism of ... Cobalt
and Nickel” (_Edin. Phil. Jour._, Vol. X. p. 183); Kohl on pure
cobalt (L. F. F. Crell’s “Neusten Ent.,” Vol. VII. p. 39);
Tyndall, “Researches on Dia-Magnetism,” London, 1870, pp. 1, 90,
etc.; Appleton’s Encyclopædia, 1870, Vol. IV. p. 10; Humboldt’s
“Cosmos,” 1859, Vol. V. p. 61; Augustin Roux, “Expériences
nouvelles ...” (_Journal de Médecine_, for November 1773).
Consult also, for Sebald J. Brugmans, “Biog. Générale,” Vol.
VII. p. 582; Bory de Saint Vincent, in the “Annales Générales de
Sciences Physiques,” Vol. II.

=A.D. 1779.=--Lord Mahon, afterward third Earl of Stanhope, an Englishman of great ingenuity and fertility in invention and a pupil of Lesage of Geneva (at A.D. 1774), publishes his “Principles of Electricity,” in which he explains the effects of the _return stroke_ or _lateral shock_ of an electrical discharge which was first observed by Benjamin Wilson (at A.D. 1746).

He imagined that when a large cloud is charged with electricity it displaces much of that fluid from the neighbouring stratum of air, and that when the cloud is discharged the electric matter returns into that portion of the atmosphere whence it had previously been taken. According to Lord Cavendish, the theory developed in the above-named work is that “A positively electrified body surrounded by air will deposit upon all the particles of that air, which shall come successively into contact with it, a proportional part of its _superabundant_ electricity. By which means, the _air_ surrounding the body will also become _positively_ electrified; that is to say, it will form round that positive body an electrical atmosphere, which will likewise be positive.... That the _Density_ of all such atmospheres decreases when the distance from the charged body is increased.”

Tyndall says (Notes on Lecture VII) that Lord Mahon fused metals and produced strong physiological effects by the return stroke.

In 1781, the English scientist, John Turberville Needham (1713–1781), published at Brussels his French translation of Lord Mahon’s work under the title of “Principes de l’Electricité.” Needham was the first of the Catholic clergy elected to a fellowship of the English Royal Society, to whose Transactions he made several contributions. His numerous works include “A letter from Paris concerning some new electrical experiments made there,” London, 1746, also a volume of researches upon the investigations of Spallanzani. The list of his communications to the _Phil. Trans._ and to the “Mém. de l’Acad. de Bruxelles” will be found in Watt’s “Bibliotheca Britannica” and in Namur’s “Bibl. Acad. Belge” (“Dict. Nat. Biog.,” Vol. XL. p. 157; _Phil. Trans._, 1746, p. 247, and Hutton’s abridgments, Vol. IX. p. 263).

REFERENCES.--“Electrical Researches” of Lord Cavendish, pp.
xlvi-xlvii; _Phil. Trans._ for 1787, Vol. LXXVII. p. 130; Dr.
Thomas Young, “Course of Lectures,” London, 1807, Vol. I. p.
664; Dr. Thomas Thomson, “History of the Royal Society,” London,
1812, p. 449; Sturgeon, “Researches,” Bury, 1850, p. 398.

=A.D. 1779.=--Ingen-housz (Johan), distinguished English physician and natural philosopher, native of Breda, publishes, _Phil. Trans._, p. 661, an account of the electrical apparatus which is by many believed to have led to the invention of the plate electrical machine, although the same claim has been made in behalf of Jesse Ramsden (at A.D. 1768). Dr. Priestley states that Ingen-housz and Ramsden invented it independently of one another. He describes a circular plate of glass nine inches in diameter turning vertically and rubbing against four cushions, each an inch and a half long and placed at the opposite ends of the vertical diameter. The conductor is a brass tube bearing two horizontal branches extending to within about half an inch of the extremity of the glass, so that each branch takes off the electricity excited by two of the cushions (Dr. Thomas Young, “Course of Lectures,” Vol. II. p. 432).

The plate machine of Dr. Ingen-housz is illustrated at p. 16 of “Electricity” in the “Library of Useful Knowledge.” For other plate machines see, more particularly, Dr. Young’s “Course of Lectures,” Vol. II. p. 431; _Phil. Trans._ 1769, p. 659; Geo. K. Winter’s apparatus with ring conductor and peculiar-shaped rubbers, as well as the great machine at the Royal Polytechnic, and that of Mr. Snow Harris, illustrated and described in Vol. III. p. 787, “Eng. Ency.--Arts and Sciences,” and at pp. 223, 224 of J. H. Pepper’s “Cyclopædic Science,” London, 1869; “Allg. deutsche Biblioth.,” B. XXIV. Anh. 4, Abth., p. 549, 1760 (Poggendorff, Vol. II. p. 465), relative to the machines of Martin Planta, Ingen-housz and Ramsden; Reiser’s plate machine (Lichtenberg and Voigt’s “Magazin für das Neueste aus der Physik,” Vol. VII. St. 3, p. 73); Ferdinando Elice, “Saggio sull’Elettricita,” Genoa, 1824 (for two electricities); J. J. Metzger’s machine (Elice, “Saggio,” second edition, p. 55); Marchese C. Ridolfi, for a description of Novelluccis’ plate electrical machine (“Bibl. Italiana,” Vol. LXIII. p. 268; “Antologia di Firenze,” for August 1824, p. 159); Robert Hare, “Description of an Electrical Plate Machine,” London, 1823 (_Phil. Mag._, Vol. LXII. p. 8). See, besides, the machines of Bertholon (rubber in motion) in Lichtenberg and Voigt’s “Magazin,” Vol. I. p. 92 and Rozier XVI. p. 74; of Brilhac (Rozier, XV. p. 377); of Saint Julien (Rozier, XXXIII. p. 367); of Van Marum (Rozier, XXXVIII. p. 447).

Dr. Ingen-housz also constructed a small magnet, of several laminæ of magnetised steel firmly pressed together, capable of sustaining one hundred and fifty times its own weight, and he found that pastes into the composition of which the powder of the natural magnet entered were much superior to those made with the powder of iron; the natural magnet, he observed, having more coercitive force than iron.

REFERENCES.--_Journal de Physique_ for February 1786, and for
May 1788, containing the letters of Dr. Ingen-housz, which
show that the vegetation of plants is in no sensible degree
either promoted or retarded by common electricity. An account
is also given of his experiments in “Versuche mit Plantzen,”
Vienna, 1778, in the “Catalogue of the Royal Society,” p.
313, in “Goth. Mag.,” Vol. V. iii. 13; Rozier, XXXII. p. 321;
XXXIV. p. 436; XXXV. p. 81; _Journal de Physique_, Vol. XXXV
for 1789. See also, _Journal de Physique_, XLV (II), 458;
Rozier, XXVIII. p. 81; M. Nuneberg, “Osservazioni ...” Milano,
1776 (“Scelta d’Opuscoli,” XVII. p. 113); Pietro Moscati,
“Lettera ...” Milano, 1781 (“Opus Scelti,” IV. p. 410); H. B.
de Saussure (_Journal de Physique_, Vol. XXV for 1784); G. da
San Martino, “Memoria ...” Vicenza, 1785; M. Schwenkenhardt,
“Von dem Einfluss ...” (Rozier, XXVII. p. 462; _Journal de
Physique_ for 1786, Vol. I); A. M. Vassalli-Eandi in the “Mem.
della Soc. Agr. di Torino,” Vol. I for 1786, particularly
regarding the experiments of Ingen-housz and Schwenkenhardt;
also in the “Giornale Sc. d’una Soc. Fil. di Torino,” Vol.
III; N. Rouland, “Elec. appliquée aux vegétaux” (_Journal de
Physique_, 1789–1790); Ingen-housz, Rouland, Dormoy, Bertholon
and Derozières (Rozier, XXXV. pp. 3, 161, 401; XXXVIII. pp. 351,
427, and in _Journal de Physique_, Vols. XXXII, XXXV, XXXVIII);
M. Carmoy, on the effects of electricity upon vegetation, in
Rozier, XXXIII. p. 339; _Jour. de Physique_ 1788, Vol. XXXIII;
M. Féburier, “Mémoire sur quelques propriétés ...”; G. R.
Treviranus, “Einfluss ...” Kiel, 1800 (Gilbert’s _Annalen_,
Vol. VII for 1801 and “Nordisches Arch. f. Nat. u. Arzneiw.,”
1st Band, 2tes Stück); C. G. Rafn (“Mag. Encyclopédique,” No.
19, Ventose An. X. p. 370), Paris, 1802; J. P. Gasc, “Mémoire
sur l’influence ...” Paris, 1823; E. Solly, “On the influence
...” London, 1845 (“Journ. of the Hortic. Society,” Vol. I. part
ii.); E. Romershausen, “Galv. El. ... Vegetation,” Marburg,
1851; M. Menon, “Influence de l’électricité sur la végétation,”
and his letters to R. A. F. de Réaumur. Consult likewise J.
Browning’s letter to H. Baker, Dec. 11, 1746 (_Phil. Trans._
for 1747, Vol. XLIV. p. 373); G. Wallerius, “Versuch ...”
Hamb. and Leipzig, 1754; (“K. Schwed. Akad. Abh.,” XVI. p.
257; also “Vetensk Acad. Handl.,” 1754;) L. F. Kamtz (Kaemtz),
“Über d. Elek ...” Nürnberg, 1829; (Schweigger’s _Journal f.
Chemie u. Physik_, Vol. LVI;) Bartolomeo Zanon, “Intorno un
punto ...” Belluno, 1840; Francesco Zantedeschi “Dell influsso
...” Venezia, 1843; (“Mem. dell Instit. Veneto,” I. p. 269;)
E. F. Wartmann, “Note sur les courants ...” Genève, 1850;
(“Bibl. Univ. de Genève,” for Dec. 1850;) T. Pine, “Connection
between Electricity and Vegetation,” London, 1840; (“Annals of
Electricity,” Vol. IV. p. 421.) For the effects of galvanism
on plants, see Giulio in “Bibl. Ital.,” Vol. I. p. 28; also
E. J. Schmuck “On the Action of Galvanic Electricity on the
_Mimosa Pudica_,” and M. Rinklake, as well as Johann W. Ritter,
“Elektrische versuche an der _Mimosa Pudica_.” For an account of
M. P. Poggioli’s observations on the influence of the _magnetic_
rays on vegetation, and the reply of F. Orioli thereto,
see Vol. I of the “Nuova collezione d’opuscoli scientifici
...” Bologna, 1817. Dr. Thomas Young’s “Course of Lectures,”
Vol. II. pp. 432–433; N. K. Molitor’s “John Ingen-housz.
Anfangsgrunde ...” 1781; Geo. Adams, “Lectures on Nat. and Exp.
Philosophy,” London, 1799, Vol. I. pp. 512–515; John Senebier,
“Expériences,” etc., 1st and 2nd Memoirs, Genève and Paris,
1788; Becquerel in the _Comptes Rendus_ for November 1850,
also Tome XXXI. p. 633; M. Buff (_Phil. Mag._ N. S. Vol. VII.
p. 122); Priestley’s “History ...” 1775, p. 487; Walsh at A.D.
1773; Cavallo’s “Exper. Philosophy,” 1803, Vol. III. p. 357;
Pouillet (Poggendorff’s _Annalen_, Vol. XI. p. 430); Reiss, in
Poggendorff’s _Annalen_, Vol. LXXIX. p. 288; G. F. Gardini, “De
inflvxu ...” s. 7, p. 10; _Philosophical Transactions_ for 1775,
1778, p. 1022; 1779, p. 537; _Journal de Physique_, Vol. XVI for
1780; “Erxleben’s phys. bibliothek,” s. 530; papers relative to
the effects of electricity upon vegetation alluded to in “Le
Moniteur Scientifique,” more particularly at pp. 904, 907, 1026,
Vol. XX for 1878, and at p. 23, Vol. XXI for 1879.

=A.D. 1780.=--Spallanzani (Lazaro), celebrated Italian naturalist, to whom the French Republic vainly offered the Professorship of Natural History at the Paris _Jardin des Plantes_, and who has been already particularly alluded to in connection with John Walsh, at A.D. 1773, writes a second treatise upon the operations of Charles Bonnet, of Geneva, as regards the effects of electricity upon nerves and muscles. He is also the author of works upon electrical fishes as well as upon meteors, etc., which will be found detailed in Vol. VII of the “Biographie Médicale,” as well as at Vol. XLIII. p. 246, of the “Biographie Universelle.”

REFERENCES.--Alibert’s Eloge in Vol. III of the “Mém. de la Soc.
Médicale d’Emulation”; “Catal. Roy. Soc. Sc. Papers,” Vol. V. p.
767; “Opus. Scelti,” Vols. VII. pp. 340, 361; VIII. p. 3; XIV.
pp. 145, 296; Brugnatelli, “Ann. di chimica” for 1793 and 1795;
“Mem. Soc. Ital.,” Vols. II. p. 11; IV. p. 476.

=A.D. 1780–1781.=--Bertholon de Saint Lazare (Pierre), French physician and Professor of Natural Philosophy, and a great friend of Dr. Franklin, publishes at Paris his “Electricité du Corps Humain ...” in which he relates more particularly his general observations upon atmospheric electricity as affecting the human body while in a healthy state and while in a diseased condition. He likewise treats of the effects of electricity upon animals, and details very interesting experiments upon the _torpedo_, which latter, he remarks, establishes the closest possible resemblance to the Leyden phial.

He is also the author of “Electricité des Végétaux” (1783), as well as of “Electricité des Météores” (1787), and of a volume entitled “Electricité des Métaux.” J. C. Poggendorff says (“Biog.-Lit. Handw. ...” Vol. II. p. 102) that J. Ferd. Meidinger (1726–1777) had previously written concerning the action of electric fire upon metals and minerals. Johann Jacob Hemmer published, at Mannheim in 1780, “Sur l’Electricité des Métaux” (“Ob. sur la Physique,” July 1780, p. 50), and A. A. De La Rive wrote in 1853 “De l’Elect. Développée ...” (“Bibl. Univ.,” Vol. LIX).

REFERENCES.--Young’s “Course of Lectures,” Vol. II. p. 431;
Ingen-housz at A.D. 1779; _Journal de Physique_, Vol. XXXV;
“Biographie Universelle,” Vol. IV. p. 149; “Biographie
Générale,” Vol. V. p. 722; Larousse, “Dict. Univ.,” Vol.
II. p. 618; “La Grande Encyclopédie,” Vol. VI. p. 450. See
also Bertholon’s “Nouvelles Preuves ...” pp. 18–19; Arago,
“Notices Scientifiques,” Vol. I. pp. 338–340, 386; “Mercure
de France,” 1782, No. 52, p. 188; Abbé d’Everlange de Wittry,
“Mém. sur l’Elec. ... dans les végétaux et le corps humain,”
read June 24, 1773--“Anc. Mém. de l’Acad. Belge,” Vol. I.
p. 181; Vassalli-Eandi, “Esame della Elett. delle Meteore
del Bertholon,” Torino, 1787; account of the experiments to
ascertain the effects of electricity on vegetation, made in
France during the summer of 1878 by MM. Grandeau, Celi and
Leclerc; and a curious publication, “Les Animaux et les Métaux
deviennent ils Electriques par communication,” by L. Béraud
(Bérault), alluded to in Poggendorff, Vol. I. p. 146.

=A.D. 1780–1783.=--Prof. Samuel Williams, at Cambridge, Mass., makes the earliest known observations of the magnetic dip in the United States, and publishes them in the “Memoirs of the American Academy of Arts,” Vol. I. pp. 62, 68. According to this authority, the dip in 1783 was 69° 41’. The next dip observations are those made during Long’s expedition to the Rocky Mountains in 1819.

REFERENCES.--“American Journal of Science,” Vol. XLIII. pp. 93,
94; “Trans. Amer. Phil. Soc.,” O. S., Vol. III. p. 115.

=A.D. 1780–1794.=--Le Père Amyot (Amiot), learned French Jesuit, who was sent in 1751 as a missionary to Pekin, where he resided till his decease in 1794, writes, on the 26th of July 1780, and also on the 20th of October 1782 that, as a result of a great number of observations, he finds no change in the variation of the magnetic needle, _i. e._ that “the point which indicates the north declines westerly from 2 to 2½ degrees, rarely more than 4½ degrees, and never less than 2 degrees.”

REFERENCES.--“Mémoires concernant l’histoire,” etc., Saillant et
Nyon, Vol. X. p. 142; Davis, “The Chinese,” Vol. III. p. 13.

=A.D. 1781.=--The so-called compass plant (_Silphium lancinatum_) is first introduced from America into Europe by M. Thouin and blooms for the first time in the Botanic Gardens of Upsala, Sweden.

In the “Scientific American” of February 26, 1881, reference is made to the interesting account of this plant given by Sir J. D. Hooker in Curtis’ “Botanical Magazine,” as well as to the following extract from Prof. Asa Gray’s report concerning it: “The first announcement of the tendency of the leaves of the compass plant to direct their edges to the north and south was made by General (then Lieutenant) Alvord, of the U.S. Army, during the year 1842, and again in 1844, in communications to the American Association for the Advancement of Science.... The lines in “Evangeline” (familiar to many readers):

“Look at this delicate plant that lifts its head from the meadow,
See how its leaves all point to the north as true as the magnet;
It is the compass plant that the finger of God has suspended,
Here on its fragile stalk, to direct the traveller’s journey,
Over the sealike, pathless, limitless waste of the desert----”

were inspired through a personal communication made by General Alvord to the poet Longfellow.

In this connection, the following article, headed “A Wonderful Magnetic Plant,” translated from _La Nature_ by the London _Court Journal_, will prove interesting: “There has been discovered in the forests of India a strange plant (_Philotacea electrica_) which possesses to a very high degree astonishing magnetic power. The hand which breaks a leaf from it receives immediately a shock equal to that which is produced by the conductor of an induction coil. At a distance of six metres a magnetic needle is affected by it, and it will be quite deranged if brought near. The energy of this singular influence varies with the hours of the day. All powerful about two o’clock in the afternoon, it is absolutely annulled during the night. At times of storm its intensity augments to striking proportions. While it rains the plant seems to succumb: it bends its head during a thunder-shower and remains without force or virtue even if one should shelter it with an umbrella. No shock is felt at that time in breaking the leaves, and the needle is unaffected by it. One never by any chance sees a bird or insect alight on this electric plant; an instinct seems to warn them that in so doing they would find sudden death. It is also important to remark that where it grows none of the magnetic metals are found, neither iron, nor cobalt, nor nickel--an undeniable proof that the electric force belongs exclusively to the plant. Light and heat, phosphorescence, magnetism, electricity, how many mysteries and botanical problems does this wondrous Indian plant conceal within its leaf and flower!”

The results of some interesting researches on plant-electricity have been reported by A. D. Waller, who finds that whenever a plant is wounded, a positive electric current is established between the wounded part and the intact parts. This may start with an electromotive force of 0·1 volt, but it afterward diminishes. He writes further:

“Actual wounding is not necessary to obtain this manifestation; an electro-positive current is set up when there is mechanical excitation, but it is much weaker (0·02 volt). And light acts like mechanical excitation with certain plants, such as the leaves of the iris, of tobacco, of the begonia, etc. From the illuminated to the darkened part flows a positive electric current that may be as strong as 0·02 volt. A similar reaction in the petals is not always observed. There is a certain correlation between the vigour of a plant and the electric reaction. The more vigorous the plant is, the stronger the current. Plants grown from fresh seeds give a more powerful current than those from old seeds. A bean a year old gave a current of 0·0170 volt; one five years old, a current of 0·0014; and the reaction is inversely and regularly proportional to the age of the seed from which the plant springs. There is observed in vegetable tissues, subjected to an excitation of the same intensity at regular intervals, the characteristic changes of reaction that are present in animal tissues--fatigue, recuperation, etc. Temperature plays a part in all these phenomena; below -4° to -6° C. [+° to + 25° F.] and above 40° C. [108° F.] there is no reaction.”

=A.D. 1781.=--Lavoisier (Antoine Laurent), an eminent French natural philosopher, the chief founder of modern chemistry as well as of the prevailing system of chemical nomenclature which ended in the expulsion of the phlogistic theory, demonstrates by experiments made in conjunction with Volta and Laplace that electricity is developed when solid or fluid bodies pass into the gaseous state. Sir David Brewster says that the bodies to be evaporated or dissolved were placed upon an insulating stand and were made to communicate by a chain or wire with a Cavallo electrometer, or with Volta’s condenser, when it was suspected that the electricity increased gradually. When sulphuric acid, diluted with three parts of water, was poured upon iron filings, inflammable air was disengaged with a brisk effervescence; and, at the end of a few minutes, the condenser was so highly charged as to yield a strong spark of negative electricity. Similar results were obtained when charcoal was burnt on a chafing dish, or when fixed air or nitrous gas was generated from powdered chalk by means of the sulphuric and nitrous acids.

The phlogistic theory alluded to above, which was so named by George Ernest Stahl in 1697 after Johann Joachim Beccher (1635–1682) had pointed out its principle in 1669, had for its most energetic defender the editor of the _Journal de Physique_, M. J. C. De La Méthérie, who is entered at A.D. 1785, and it was in order to offset the influence which this gave him that the antiphlogistians established the _Annales de Chimie_, so frequently mentioned in these pages.[52]

REFERENCES.--George Adams’ “Lectures on Nat. and Exp.
Philosophy,” London, 1799, Vol. I. pp. 575–587, wherein
Lavoisier’s system is confuted by the German chemist Wieglib,
whose views are endorsed by Mr. Green, while for Stahl and
Beccher, refer to Sir H. Davy, “Bakerian Lectures,” London,
1840, p. 102, note, to “Biog. Gén.,” Vol. V. pp. 85–87; “Meyer’s
Konvers. Lexikon,” Vol. II. p. 654, and to Thomson’s “Hist. of
Roy. Soc.,” London, 1812, p. 467. See also J. M. G. Beseke,
“Ueber elementärfeuer ...” Leipzig, 1786; G. A. Kohlreif,
“Sollte die elektricität ...” Weimar, 1787; Lavoisier and
Laplace, in the “Mém. de l’Acad. Roy. des Sciences” for 1781, p.
292; Lavoisier’s “Opuscules ...” 1774, and his “Rapport ... mag.
animal.,” Paris, 1784; Dr. Thomas Thomson, “Hist. Roy. Soc.,”
pp. 479–486; Herschel’s “Nat. Phil.,” concerning the third age
of chemistry; Grégoire, “Dict. d’hist.,” etc., p. 1171; Miller’s
“Hist. Phil. Illus.,” London, 1849, Vol. IV. pp. 332–333,
notes. Chap. IV of the “History of Chemistry,” Ernst Van Meyer,
tr. by George McGowan, London, 1898, entitled “History of the
Period of the Phlogiston Theory from Boyle to Lavoisier,” will
prove interesting. “La chimie constituée par Lavoisier,” Jacob
Volhard, in “Le Moniteur Scientifique,” du Dr. Quesneville, Vol.
XIV for 1872, pp. 50–71; “Nouveau Larousse,” Vol. V. p. 608;
“La Révolution chimique,” M. Berthelot, Paris, 1890; “Essays in
Historical Chemistry,” T. E. Thorpe, London, 1894, pp. 87, 110;
“Journal des Savants” for Nov. 1859 and Feb. 1890; “Lives of Men
of Letters and Science,” by Henry, Lord Brougham, Philadelphia,
1846, pp. 140–166.

=A.D. 1781.=--Achard (Franz Carl), able chemist and experimental philosopher, born in Prussia but of French extraction, communicates to the “Mém. de Berlin” a report of many very interesting experiments made by him, which are reviewed by Prince Dmitri Alexewitsch Fürst Gallitzin, in Vol. XXII of the _Journal de Physique_.

He had previously published essays upon the electricity of ice and the electricity developed on the surface of bodies, as well as upon terrestrial magnetism, the electrophorus, etc. He made many notable investigations to prove that fermentation is checked by electricity and that putrefaction is hastened both in electrified meats and in animals killed by the electric shock.

One of his experiments illustrating galvanic irritation so greatly interested Humboldt that the latter repeated it with different animals, not doubting but small birds might in many cases be brought back to life when they fall into a state somewhat resembling death. On one occasion, he took a linnet about to expire and, having established the necessary communication, perceived, the moment the contact took place, that the linnet opened its eyes, stood erect upon its feet and fluttered its wings; it breathed, he says, during six or eight minutes and then expired tranquilly.

It was a namesake of Achard who invented the electro-magnetic brake which will be found described and illustrated in articles from the London _Engineer_ and _Engineering_, reproduced through the _Scientific American Supplements_, No. 111, p. 1760, and No. 312, p. 4974.

REFERENCES.--Poggendorff, “Biog.-Lit. Hand. ...” Vol. I. p.
7; “Biographie Générale,” Vol. I. p. 176; “Cat. Roy. Soc. Sc.
Papers,” Vol. I. p. 9; “Opus. Scelt.,” Vols. III. p. 313; V. p.
351; VI. p. 199; Reuss, _Repertorium_, Vol. IV. p. 351; Dr. G.
Gregory, “Economy of Nature,” London, 1804, Vol. I. p. 317; Van
Swinden, “Recueil ...” La Haye, 1784, Vol. I. p. 24; “Biographie
Universelle,” Vol. I. p. 114; “Journal Lit. de Berlin,” for
1776; Cavallo, London, 1777, p. 403; “Mém. de Berlin” for
1776–1780, 1786, 1790–1791; Sturgeon, “Lectures,” London, 1842,
p. 12; Geo. Adams, “Essay on Electricity,” etc., London, 1785,
pp. 214–220, 277; “Gött. Mag.,” Vol. II. ii. 139; Rozier, VIII.
p. 364; XV. p. 117; XIX. p. 417; XXII. p. 245; XXIII. p. 282;
XXV. p. 429; XXVI. p. 378; _Phil. Mag._, Vol. III. p. 51.

=A.D. 1781.=--Kirwan (Richard), LL.D., F.R.S., an Irish chemical philosopher of great eminence, who became President of the Dublin Society and of the Royal Irish Academy, receives from the English Royal Society its gold Copley medal for the many valuable scientific papers communicated by him to the latter body. These papers embrace his “Thoughts on Magnetism,” wherein he treats at length of attraction, repulsion, polarity, etc., as shown in the review given at pp. 346–353 of the eighth volume of Sturgeon’s “Annals of Electricity,” etc.

It is said that Kirwan first suggested the notion of molecular magnets, but, according to Dr. J. G. M’Kendrick, it was not till a definite form was given thereto by Weber that it acquired any importance.

REFERENCES.--_Transactions Royal Irish Academy_, Vol. VI; Ninth
“Encycl. Britannica,” Vol. XV. p. 276; _Phil. Mag._, Vol. XXXIV.
p. 247; Thomson, “Hist. of the Roy. Soc.,” p. 483; “Bibl.
Britan.,” An. VII. vol. xii. p. 105.

=A.D. 1781.=--Mauduyt (Antoine René) (1731–1815), Professor at the Collège de France, publishes several observations from which he concludes that the application of electricity is favourable in cases of paralysis. He was in the habit of placing the patient upon an insulated stool, in communication with the conductor of an electrical machine. De La Rive, who mentions the fact (“Electricity,” Chap. III. pp. 586, 587), observes that the effect, if any, could only proceed from the escape of electricity into the air.

REFERENCES.--Bertholon, _Elec. du Corps. Humain_, 1786, Vol.
I. pp. 275–276, 302, 439, 447, etc., and Vol. II. pp. 7 and
296; “Mémoire sur les différentes manières d’administrer
l’électricité,” etc., Paris, 1784; “Recueil sur l’électricité
médicale,” etc., containing articles by G. F. Bianchini, De
Lassoné, Deshais (_see_ Sauvages), Dufay, Jallabert, Pivati,
Quellmalz, Veratti, Zetzell, etc.; K. G. Kuhn’s works published
at Leipzig, 1783–1797; E. Ducretet in “Le Cosmos,” Paris, Oct.
3, 1891, pp. 269–272; P. Sue, aîné, “Hist. du Galvan,” Paris,
An. X-XIII, 1802, Vol. I. p. 40; and Vol. II. p. 382; “Grande
Encyclop.,” Vol. XXIII. p. 415.

=A.D. 1781–1783.=--Don Gauthey--Gauthier or Gualtier--a monk of the Order of Citeaux, improved upon the invention of Dupuis (at A.D. 1778) and constructed a telegraph, which he submitted at the Académie des Sciences to Dr. Franklin as well as to Condorcet and De Milly, by whom it was recommended to the French Government. In his prospectus, published during 1783, he relates that he has discovered a new mode of rapid transmission enabling him to convey intelligence and sound, by means of water pipes, a distance of fifty leagues in fifty minutes. Ternant, who states this at pp. 33 and 34 of _Le Télégraphe_, Paris, 1881, adds that, as no action was taken at the time upon the prospectus, it doubtless still lies in the archives of the Academy.

REFERENCES.--Laurencin, _Le Télégraphe_, p. 9; Eng. Cycl., “Arts
and Sciences,” Vol. VIII. p. 65; “Penny Cycl.,” 1842, Vol. IV.
p. 146.

=A.D. 1782.=--Nairne (Edward), an English mathematical instrument maker, publishes papers on electricity describing his invention of a cylinder machine which is illustrated and described at p. 15 of the chapter on “Electricity” in “Library of Useful Knowledge,” 1829. In this, as has been truly said, are seen all the essential parts of the frictional apparatus now in use.

This machine, according to Cuthbertson, was originally constructed in 1774, and was far more powerful than any before made. Nairne also constructed the largest battery known up to that time. It contained 50 square feet of coated surface, and it could be given so high a charge as to ignite 45 inches of iron wire ¹⁄₁₅₀ of an inch diameter, which up to that period was the greatest length of wire ever ignited. Nairne, while improving upon some of Priestley’s experiments, found that a piece of hard drawn iron wire, ten inches long and one-hundredth of an inch diameter, after receiving successively the discharge of 26 feet of coated glass (nine jars), was shortened three-fortieths of an inch by such discharge. Dr. Priestley had previously observed that a chain 28 inches long was shortened one quarter of an inch after having had transmitted through it a charge of 64 square feet of coated glass, and Brooke Taylor found that by passing a charge of nine bottles of 16 feet of coated surface nine times in succession through a steel wire 12 inches long and one one-hundredth of an inch diameter, the wire was shortened one and one-half inches, or one-eighth its entire length.

To Nairne was granted the third English patent in the Class of Electricity and Magnetism, the first having been issued to Gowin Knight in 1766 (see A.D. 1746) and the second to Gabriel Wright, June 25, 1779, for “a new constructed azimuth and amplitude compass.” Knight subsequently covered other similar inventions, July 5, 1791, and Jan. 19, 1796. Nairne’s patent bears date Feb. 5, 1782, No. 1318, and is for what he calls “The Insulated Medical Electrical Machine,” the conductors of which are so arranged as to readily give either shocks or sparks. He says that “by means of the conductors and jointed tubes, the human body can be in any part affected with either kind of electricity in any convenient manner.”

REFERENCES.--_Philosophical Transactions_ for 1772, 1774,
1778, 1780, 1783, Vol. LXIV. p. 79; Vol. LXVIII. p. 823; Vol.
LXX. p. 334; also Hutton’s abridgments, Vol. XIII. pp. 360
(dipping needle), 498; Vol. XIV. pp. 427–446, 688; Vol. XV.
p. 388; “General Biog. Dict.,” London, 1833, by John Gorton,
Vol. I. (n. p.); Cuthbertson, “Practical Electricity,” London,
1807, pp. 165–168; article “Electricity,” in the “Encycl.
Britannica”; “Description of ... Nairne’s ... Machine,” London,
1783 and 1787; Caullet de Veaumorel, “Description de la machine
électrique négative et positive de Mr. Nairne,” Paris, 1784;
Delaunay’s “Manuel,” etc., Paris, 1809, pp. 7, 12–14.

=A.D. 1782–1783.=--Linguet (Simon, Nicolas, Henri), French advocate (1736–1794), who was an associate of Mallet du Pan in the preparation of the _Annales Politiques_ and who was later on committed to the Bastille in consequence of a visit which he imprudently made to Paris, writes a letter to the French Ministry proposing a novel method of transmitting messages of any length or description by means of some kind of a telegraph, “nearly as rapidly as the imagination can conceive them.” He adds, “I am persuaded that in time it will become the most useful instrument of commerce for all correspondence of that kind; just as electricity will be the most powerful agent of medicine; and as the fire-pump will be the principle of all mechanic processes which require, or are to communicate, great force.”

To Linguet has been attributed the authorship of the anonymous letter which appeared in the _Journal de Paris_ of May 30, 1782, and in _Le Mercure de France_ of June 8, 1782, wherein it is proposed to employ twenty-four pairs of gilt wires, placed underground in separate wooden tubes filled with resin and bearing a knob at each extremity. Between each pair of knobs was to be placed a letter of the alphabet, which would become discernible whenever the electric spark was passed through the wire by means of the Leyden phial.

REFERENCES.--Ternant, _Le Télégraphe_, Paris, 1881, p. 11;
Linguet, “Mém. manuscrit ... signaux par la lumière,” Paris,
1782; all about the “Mercure de France,” in “Bulletin du
Bibliophile” No. 7 of July 15, 1902; “Biog. Dict.,” Alex
Chalmers, 1815, Vol. XX. p. 290; “Nouv. Biog. Gén.” (Hœfer),
Paris, 1860, Vol. XXXI. p. 279; “Biog. Univ.” (Michaud), Vol.
XXIV. p. 565.

=A.D. 1782–1791.=--Cassini (Jean Jacques Dominique, Comte de), son of Cassini de Thury, eminent astronomer, makes the very important announcement that, besides the _secular_ variation of the declination, the magnetic needle is subject to an _annual_ periodical fluctuation depending on the position of the sun in reference to the equinoctial and solstitial points.

Cassini’s discovery is contained in a Memoir consisting of two parts, the first part being a letter addressed to L’Abbé Rosier and published by him in the _Journal de Physique_, while the second part, composed at request of the Académie des Sciences, is that which specially treats of the _annual variation in declination_.

Besides the last named, we have thus far learned of the _secular_ variation discovered by Gellibrand (Hellibrand) in 1635, as well as of the _diurnal_ and _horary_ variations, first accurately observed by George Graham during the year 1722, and we have likewise been informed of the earliest observations of _the dip or inclination_, made independently by both Georg Hartmann (A.D. 1543–1544) and by Robert Norman (A.D. 1576), as well as of the determination of the intensity of the inclination by J. C. Borda (at A.D. 1776). For accounts of the _secular_ and _annual_, as well as of the _diurnal_ and _horary_ variations of the dip, the reader should consult the First Section of Humboldt’s “Cosmos” treating of telluric phenomena and some of the very numerous references therein given.

Speaking of the influence of the sun’s position upon the manifestation of the magnetic force of the earth, Humboldt remarks that the most distinct intimation of this relation was afforded by the discovery of _horary_ variations, although it had been obscurely perceived by Kepler, who surmised that all the axes of the planets were magnetically directed toward one portion of the universe. He says that the sun may be a magnetic body, and that on that account the force which impels the planets may be centred in the sun (Kepler, in “Stella Martis,” pp. 32–34--compare with it his treatise, “Mysterium Cosmogr.,” cap. 20, p. 71). He further observes that the _horary_ variations of the declination, which, although dependent upon true time are apparently governed by the sun as long as it remains above the horizon, diminish in angular value with the magnetic latitude of place. Near the equator, for instance, in the island of Rawak, they scarcely amount to three or four minutes, whilst the variations are from thirteen to fourteen minutes in the middle of Europe. As in the whole northern hemisphere the north point of the needle moves from east to west on an average from 8½ in the morning until 1½ at midday, in the southern hemisphere the same north point moves from west to east (Arago, _Annuaire_, 1836, p. 284, and 1840, pp. 330–358). Attention has been drawn, with much justice, to the fact that there must be a region of the earth, between the terrestrial and the magnetic equator, where no horary deviations in the declination are to be observed. This fourth curve (in contradistinction to the _isodynamic_, _isoclinic_ and _isogonic_ lines, or those respectively of equal force, equal inclination and equal declination), which might be called the _curve of no motion_, or rather _the line of no variation of horary declination_, has not yet been discovered. No point has hitherto been found at which the needle does not exhibit a _horary_ motion, and, since the erection of magnetic stations, the important and very unexpected fact has been evolved that there are places in the southern magnetic hemisphere at which the _horary_ variations of the dipping needle alternately participate in the phenomena (types) of the hemispheres.

Humboldt also alludes, in the article on “Magnetic Variation,” to his recognition of the “four motions of the needle, constituting, as it were, four periods of magnetic ebbing and flowing, analogous to the barometrical periods,” which will be found recorded in Hansteen’s “Magnetismus der Erde,” 1819, s. 459, and he likewise refers to the long-disregarded _nocturnal_ alterations of variation, for which he calls attention to Faraday “On the Night Episode,” ss. 3012–3024. (See also, Poggendorff’s _Annalen der Physik_, Bd. XV. s. 330, and Bd. XIX. s. 373.)

The _Phil. Trans._ for 1738, p. 395, contain the description of a new compass for ascertaining the variation “with greater ease and exactness than any ever yet contrived for that purpose.” This was devised by Capt. Christopher Middleton, whose many interesting observations are to be found in the same volume of the _Phil. Trans._, p. 310, as well as in the volumes for 1726, p. 73; 1731–1732, 1733–1734, p. 127; 1742, p. 157, and in John Martyn’s abridgment, Vol. VIII. part i. p. 374. Reference should also be made to the volumes for 1754 (p. 875) and 1757 (p. 329), giving the reports of W. Mountaine and J. Dodson upon the magnetic chart and tables of 50,000 observations, likewise to the volume for 1766 containing the report of W. Mountaine on Robert Douglass’ observation, as well as for the record of investigations of the variation made by David Ross on board the ship “Montagu” during the years 1760–1762.

REFERENCES.--Sabine, “On the Annual and Diurnal Variations” in
Vol. II of “Observations made ... at Toronto,” pp. xvii-xx, also
his Memoir “On the Annual Variation of the Magnetic Needle at
Different Periods of the Day,” in _Phil. Trans._ for 1851, Part
II. p. 635, as well as the Introduction to his “Observations
... at Hobart Town,” Vol. I. pp. xxxiv-xxxvi, and his Report
to the British Association at Liverpool, 1854, p. 11--_Phil.
Trans._ for 1857, Art. 1, pp. 6, 7--relative to the _lunar
diurnal magnetic variation_. See likewise C. Wolf, “Histoire
de l’observatoire depuis sa fondation à 1793”; Houzeau et
Lancaster, “Bibl. Gen.,” Vol. II. p. 102; “Mém. de Paris,” Vol.
II. p. 74, and Vol. VII. pp. 503, 530; Walker, “Ter. and Cos.
Magn.,” Chap. III; Mme. J. Le Breton, “Histoire et Applic.,”
etc., Paris, 1884, p. 17; Robison, “Mech. Phil.,” Vol. IV. p.
356; Thos. Young, “Nat. Phil.,” 1845, p. 583.

CASSINI FAMILY

This celebrated family, to which allusion was made under A.D. 1700, deserves here additional notice.

Giovanni Domenico Cassini (1625–1712), the first and greatest of the name, succeeded Buonaventura Cavaliéri in the astronomical chair of the Bologna University in 1650, and remained there until given the directorship of the Paris Royal Observatory upon its completion in 1670. Partly with the assistance of his learned nephew, James Philip Maraldi, Cassini made many important discoveries, among which may be signalled the finding of the first, second, third and fifth satellites of Saturn, as well as the dual character of that planet’s ring, the determination of the rotation of Jupiter, Mars and Venus, and the laws of the moon’s axial rotation. (See Thomson, “Hist. of the Roy. Soc.,” p. 331; “Anc. Mém. de Paris,” I, VIII, X; Thos. Morrell, “Elem. of the Hist. of Phil. and Sc.,” London, 1827, pp. 377–379.)

Jacques (James) Cassini (1677–1756), the only son of the preceding, became director of the Paris Observatory upon the death of his father, made many very important astronomical observations, and wrote several treatises upon electricity, etc. In one of his works, “De la Grandeur et de la Figure de la Terre,” Paris, 1720, he gives an account of the continuation of the measurement of Picard’s arc of the meridian from Paris northward, begun by Domenico Cassini and La Hire in 1680, and recommenced by Domenico and Jacques Cassini in 1700. (See “Mém. de Paris,” Vol. VII. pp. 455, 456, 508, 572; and for years 1705, pp. 8, 80; 1708, pp. 173, 292; 1729, Hist. I., Mem. 321.)

Cesar François Cassini de Thury (1714–1784), son of Jacques, whom he in turn succeeded at the Observatory, was, as above stated, the father of Jean Dominique Cassini (1747–1845). He made numerous researches while in the Director’s Chair, his most remarkable work being the large triangulation of France published in 1744, under the title of “La Méridienne,” etc. (See “Hist. de l’Acad. des Sciences de Paris” pour 1752, p. 10.)

=A.D. 1783.=--Robespierre (François-Maximilien-Joseph-Isidore de), who afterward became leader of the famous French Jacobin Club, and was at the time practising law in his native town of Arras, distinguishes himself by successfully defending the cause of the Sieur de Vissery de Boisvalé, a landed proprietor of that place, who had erected a lightning conductor on his house, “much to the scandal of the discreet citizens” of the locality--“Deistical philosophy; away with it!” (Eighth “Britannica,” Vol. XIX. p. 233).

Mr. de Boisvalé’s case was an appeal from a judgment delivered by the sheriff of Saint-Omer, ordering the destruction of the lightning conductor, and its printed report bears the following epigraph:

“L’usage appuyé sur les temps
Et les préjugés indociles.
Ne se retire qu’à pas lents
Devant les vérités utiles.”

Jean Paul Marat, docteur en médecine et médecin des Gardes de corps de M. le Comte d’Artois, who, like Robespierre, was a member of the French National Convention as well as a declared enemy of the Girondins, and who was killed by Charlotte Corday, July 13, 1793, made many electrical experiments. These greatly interested Benjamin Franklin, who used to visit him (Ninth “Encycl. Brit.,” Vol. XV. p. 526). He was the author of many electrical works during the years 1779–1784, notably “Découvertes sur le feu, l’électricité et la lumière,” “Recherches Physiques,” and a memoir on medical electricity (“Œuvres de Marat,” Paris, 1788; A. Bougeart, “Marat, l’ami du peuple,” 1864; F. Chevremont, “Jean Paul Marat,” 1881).

REFERENCES.--Ronalds’ “Catalogue,” p. 434; _La Lumière
Electrique_ for Sept. 5, 1891; the _Electrician_, London, Sept.
11, 1891.

=A.D. 1783.=--Wilkinson (C. H.), Scotch physician, publishes at Edinburgh his “Tentamen Philosophico-medicum de Electricitate,” which is followed, during 1798 and 1799, by other works upon electricity, wherein he cites a number of marvellous cures of intermittent fevers similar to those made by Cavallo, also of amaurosis (_goutte sereine_) and of quinsy (_squinancie_) like those performed by Lovet, Becket and Mauduyt.

During the year 1804 appeared the first edition, in two volumes, of his “Elements of Galvanism in Theory and Practice,” containing a very comprehensive review of the discovery from the time of Galvani’s early experiments. In this last-named work, however, he shows that incipient amaurosis and the completely formed gutta serena have not yielded to his own treatment by galvanic influence as had been the case with Dr. C. J. C. Grapengieser, who published many accounts of surprising cures (Grapengieser, “Versuche den Galvanismus ...” Berlin, 1801 and 1802, or Brewer and Delaroche, “Essai ...” Paris, 1802). The whole of Chap. XXXVI is devoted to the application of galvanism to medicine, whereto allusion had already been made in the first chapter of the same work.

Wilkinson refers also to the electricity of the _torpedo_, and to the observations made thereon by Hippocrates, Plato, Theophrastus, Pliny and Ælian, also by Belon, Rondelet, Salviana and Gesner, as well as by Musschenbroek, Redi, Réaumur, Walsh, Hunter, Spallanzani, ’Sgravesande, Steno, Borelli, Galvani and others. Much space is likewise given to the observations recorded on animal electricity, notably by Fontana, De La Méthérie, Berlinghieri, Vassali-Eandi, Humboldt, Pfaff, Lehot, Hallé, Aldini, and to the experiments of Valli as they were repeated before the French Academy of Sciences and before the Royal Society of Medicine of Paris, in presence of M. Mauduyt. When treating of the powers of galvanism as a chemical agent, reference is made to the decomposition of water, thus first effected in 1795 by Creve, the discoverer of metallic irritation, and to the operations of Nicholson and Carlisle, Dr. Henry, Cruikshanks, Haldane, Henry Moyes, Richter, Gibbes, etc.

REFERENCES.--J. J. Hemmer, “Commentat Palatinæ,” VI, Phys.,
p. 47; Bertholon, “Elec. du Corps Humain,” 1786, Vol. I. pp.
314, 330, 483, and Vol. II. p. 299; “Bibl. Britan.,” 1808,
Vol. XXXVIII. p. 270 (_Phil. Mag._, No. 105); _Annales de
Chimie_, Vol. LXXVIII. p. 247; _Phil. Mag._, Vol. XXIX. p. 243,
and Vol. XLIX. p. 299; F. Buzzi, “Osservazione ... amaurosi
... elettricita,” Milano, 1783 (“Opus. Scelti,” Vol. VI. p.
359); _Nicholson’s Journal_, Vol. VIII. pp. 1, 70, 206; also
Vol. X. pp. 30–32, for letter relative to certain erroneous
observations of Mr. Wilkinson respecting galvanism, by Mr. Ra.
Thicknesse, who also wrote in Vol. IX. pp. 120–122, explaining
the production of the electric fluid by the galvanic pile.

=A.D. 1783.=--Saussure (Horace-Benedict de), Professor of Physics at the University of Geneva and founder of the Society for the Advancement of the Arts in the same city, is the inventor of an electrometer designed to ascertain the electrical state of the atmosphere, which will be found described in Vol. VIII. p. 619 of the 1855 “Encycl. Britannica.”

He observed that electricity is strongest in the open-air, that it is weak in streets, under trees, etc., and that during the summer and winter, by night as well as by day, when the atmosphere is free from clouds, the electricity of the air is always positive. In contradistinction, Mr. T. Ronayne found in Ireland that the electricity of the atmosphere is positive in winter when the air is clear, but that it diminishes in frosty or foggy weather and that he could detect no electricity in the air during summer except on the approach of fogs, when the electricity proved to be positive. During the year 1785, M. de Saussure observed at Geneva that, during the winter, the intensity of atmospherical electricity attained its first maximum at 9 a.m., diminishing from that hour until it reached its minimum at 6 p.m., after which it began to increase until attaining its second maximum at 8 p.m., diminishing gradually thereafter till it recorded its second minimum at 6 a.m. During the summer he found the electricity increasing from sunrise till between 3 and 4 p.m., when it would reach its maximum; after that it appeared to diminish till the dew fell, when it again became stronger, but was scarcely sensible during the night.

Sir David Brewster informs us in his able article on “Electricity” in the “Britannica” that De Saussure made a number of elaborate experiments on the electricity of evaporation and combustion. He observed at first that the electricity was sometimes positive and sometimes negative when water was evaporated from a heated crucible, but in his subsequent trials he found it to be always positive in an iron and in a copper crucible. In a silver, also in a porcelain crucible, the electricity was negative and the evaporation of both alcohol and of ether in a silver crucible also gave negative electricity. M. de Saussure made many fruitless attempts to obtain electricity from combustion, and he likewise failed in his efforts to procure it from evaporation without ebullition.

To De Saussure is often erroneously attributed the authorship of Lullin’s “Dissertatio physica de electricitate,” alluded to at A.D. 1766.