Chapter XXVII: Part II: pp. 254–256, 279, for some of his other correspondence (4)

REFERENCES.--“Memoirs of Dalton’s Life,” by Dr. W. C. Henry,
London, 1854; “Life and Discoveries of Dalton,” in _British
Quarterly Review_, No. 1; _Pharmaceutical Journal_, London,
October 1841; Thomson’s “History of Chemistry,” Vol. II; Young’s
“Course of Lectures,” London, 1807, Vol. I. pp. 706–709, 753,
and Vol. II. pp. 466–470; Noad, “Manual,” etc., London, 1859,
pp. 226, 269, 534; article, “Aurora Borealis,” immediately
following A.D. 1683; Sir H. Davy, “Bakerian Lectures,” London,
1840, pp. 322, 323, 328–330; “Dict. of Nat. Biog.,” Vol. XIII.
pp. 428–434, as well as the numerous references therein cited.
Consult also, for theories, investigations, observations,
records, etc., of the Aurora Borealis: Georg. Kruger, 1700; J.
J. Scheuchzer, 1710–1712, 1728–1730; L. Feuillée, 1719; J. L.
Rost, 1721; J. C. Spidberg, 1724; W. Derham, 1728, 1729–1730;
F. C. Mayer--Meyer, 1726; J. F. Weidler, 1729, 1730, 1735; J.
Lulolfs, 1731; M. Kelsch, 1734; F. M. Zanotti, 1737, 1738; also
Zanotti and P. Matteucci, 1739; B. Zendrini, J. Poleni, F. M.
Serra, E. Sguario and D. Revillas in 1738; G. Bianchi, 1738 and
1740; J. M. Serantoni, 1740; G. C. Cilano de Maternus, 1743; S.
von Trienwald, 1744; G. Guadagni, 1744; J. F. Ramus, 1745; C.
Nocetus, 1747; P. Matteucci, 1747; Jno. Huxham, 1749–1750; G. W.
Krafft, 1750; P. Kahm--Kalm, 1752; G. Reyger, 1756; A. Hellant,
1756, 1777; Jos. Stepling, 1761; H. Hamilton, 1767, 1777; M. A.
Pictet, 1769; J. E. Silberschlag, 1770; C. E. Mirus, 1770; J. E.
B. Wiedeburg, 1771; Max. Hell, 1776; Mr. Hall, J. H. Helmuth,
1777; E. H. de Ratte, W. L. Krafft, 1778; J. E. Helfenzrieder,
1778; G. S. Poli, 1778–1779; Marcorelle and Darguier, 1782; L.
Cotte, 1783; J. A. Cramer, 1785; D. Galizi, in A. Calogera’s
“Nuova Raccolta ...” Vol. XXXIX. p. 64; J. L. Boeckmann, in
“Mem. de Berlin” for the year 1780; H. Ussher, 1788; G. Savioli,
1789, 1790; J. J. Hemmer, 1790; P. A. Bondoli, 1790, 1792, 1802;
A. Prieto, 1794; J. D. Reuss’s works published in Göttingen;
Jacopo Penada, 1807–1808; M. Le Prince, “Nouvelle Théorie
...”; W. Dobbie, 1820, 1823; Col. Gustavson, in _Phil. Mag._
for 1821, p. 312; M. Dutertre, 1822; J. L. Späth, 1822; Chr.
Hansteen, 1827, 1855; L. F. Kaemtz, 1828, 1831; G. W. Muncke,
1828; J. Farquharson, 1829; D. Angelstrom, Rob. Hare, 1836; Ant.
Colla, 1836, 1837; L. Pacinotti, 1837; G. F. Parrot, 1838; J.
H. Lefroy, 1850, 1852; Don M. Rico-y-Sinobas, 1853; A. A. de La
Rive, 1854; A. Boué (_Katalog_), 1856, 1857; C. J. H. E. Braun,
1858; E. Matzenauer, 1861; F. Dobelli, 1867; F. Denza, 1869.

=A.D. 1793–1797.=--Robison (John), a very distinguished English natural philosopher, completes what are without question the most important of all his scientific publications. These are to be found throughout the eighteen volumes and two supplements to the third “Encyclopædia Britannica,” where they cover such subjects as Physics, Electricity, Magnetism, Thunder, Variation, etc. etc. Taken together, “they exhibited,” according to Dr. Thomas Young, “a more complete view of the modern improvements of physical science than had previously been in the possession of the British public.”

It was after his retirement from the navy that Robison devoted himself to scientific studies, becoming the successor of Dr. Black in the lectureship of chemistry at the University of Glasgow during 1766, and accepting, seven years later (1773), the Professorship of Natural Philosophy at Edinburgh, where he taught all branches of physics and of the higher mathematics. In 1783 he was made Secretary of the Philosophical Society of Edinburgh, received the degree of Doctor of Laws, 1798–1799, and was elected foreign member of the Saint Petersburg Academy of Sciences in 1800. Of him, Mr. James Watt wrote, Feb. 7, 1805: “He was a man of the clearest head and the most science of anybody I have known” (Arago’s “Eloge of Jas. Watt,” London, 1839, p. 81).

It was while acting as midshipman under Admiral Saunders that Robison himself observed the effect of the aurora borealis on the compass, which had been remarked by Hiörter, Wargentin, and Mairan several years before, but which was not then generally known. The aurora borealis, he afterwards wrote, “is observed in Europe to disturb the needle exceedingly, sometimes drawing it several degrees from its position. It is always observed to increase its rate of deviation from the meridian; that is an aurora borealis makes the needle point more westerly. This disturbance sometimes amounts to six or seven degrees, and is generally observed to be greatest when the aurora borealis is most remarkable.... Van Swinden says he seldom or never failed to observe aurora borealis immediately after any anomalous motion of the needle, and concluded that there had been one at the time, though he could not see it.... This should farther incite us to observe the circumstance formerly mentioned, viz., that the South end of the dipping needle points to that part of the heavens where the rays of the aurora borealis appear to converge....”

The experiments of J. H. Lambert (at A.D. 1766–1776) upon the laws of magnetic action were carefully repeated by Robison, who, in 1769 or 1770, tried various methods and made numerous investigations from which he deduced that the force is inversely as the square of the distance. When he observed, however, some years afterward, that Æpinus had in 1777 conceived the force to vary inversely as the simple distance, he carefully again repeated the experiments and added others made with the same magnet and with the same needle placed at one side of the magnet instead of above it. By this simple arrangement the result was still more satisfactory, and the inverse law of the square of the distance was well established.

Throughout his numerous investigations, Prof. Robison found that when a good magnet was struck for three-quarters of an hour, and allowed in the meantime to ring, its efficacy was destroyed, although the same operation had little effect when the ringing was impeded; so that the continued exertion of the cohesive and repulsive powers appears to favour the transmission of the magnetic as well as of the electric fluid. The internal agitation, produced in bending a magnetic wire around a cylinder, also destroys its polarity, and, it is said, the operation on a file has the same effect. M. Cavallo found that brass becomes generally much more capable of being attracted when it has been hammered, even between two flints; and that this property is again diminished by fire: in this case, Dr. Thomas Young remarks, it may be conjectured that hammering increases the conducting power of the iron contained in the brass, and thus renders it more susceptible of magnetic action.

Of his other very important observations in the same line it would be difficult to select the most interesting, and it may suffice to call attention merely to such as are noted throughout Prof. Alfred M. Mayer’s valuable contributions on “The Magnet, Magnetism,” etc., in Johnson’s “New Universal Encyclopædia,” as well as in his “Practical Experiments in Magnetism,” etc., published through the columns of the _Scientific American Supplement_.

Prof. Robison’s electrical investigations are scarcely less interesting. In the theories advanced by Æpinus and Cavendish it was shown that the action of the electrical fluid diminished with the distance, while M. Coulomb proved, by a series of elaborate experiments, that it varied like gravity in the inverse ratio of the square of the distance. Robison had previously determined that in the mutual repulsion of two similarly electrified spheres the law was slightly in excess of the inverse duplicate ratio of the distance, while in the attraction of oppositely electrified spheres the deviation from that ratio was in defect; and he therefore arrived at the same conclusion formed by Lord Stanhope, that the law of electrical attraction is similar to that of gravity.

At the close of Richard Fowler’s “Experiments and Observations,” etc., Edinburgh, 1793, is a letter from Prof. Robison, wherein he gives the following results of many curious investigations, mostly made upon himself, to ascertain the effects of the galvanic influence. He found the latter influence well defined on applying one of two metallic substances to a wound which he had accidentally received; discovered by their tastes the solders in gold and silver trinkets; and showed that the galvanic sensation can be felt when the metallic substances are placed at a distance from each other. He proved the last-named fact by placing a piece of zinc between one of the cheeks and the gums, and a piece of silver on the opposite side within the other cheek. He next introduced a zinc rod between the piece of zinc and the cheek on the one side, and a silver rod between the silver and the cheek on the other, and when he afterward carefully brought into contact the extremities of the rods outside the mouth a flash appeared and a powerful sensation was noticeable in the gums. He experienced the same sensation when he again separated the rods and brought them to a short distance from each other, but he could perceive no galvanic effect when he placed the rods (or wires) in such manner that the silver rod should touch the zinc or the zinc rod touch the piece of silver. He also ascribed to galvanic effect the well-known fact that the drinking of porter out of a pewter pot produces a more brisk sensation than when it is taken out of a glass vessel. In this instance, he says there is a combination of one metal and of two dissimilar fluids. In the act of drinking, one side of the pewter pot is exposed to the saliva and the humidity of the mouth, while the other metallic side is in contact with the porter. In completing the circuit, in the act of drinking, a brisk and lively sensation arises, which imparts an agreeable relish to the liquid. He likewise observed that the conducting power of silk thread depends greatly on its colour, or rather on the nature of its dye. When of a brilliant white, or a black, its conducting power is the greatest; while either a high golden yellow or a nut-brown renders it the best insulator. Human hair, when completely freed from everything that water could wash out of it, and then dried by lime and coated with lac, was equal to silk.

Robison’s last publication was made in 1804, one year before his death, and constituted the first part of a series which was to appear under the head of “Elements of Mechanical Philosophy.” This portion, together with some MSS. intended for the second part, and his principal articles contributed to the “Encyclopædia Britannica,” were collected in 1822 by Sir David Brewster, and published with notes in 4 vols. under the title of “System of Mechanical Philosophy.”

REFERENCES.--Playfair in “Transactions of the Royal Society of
Edinburgh,” Vol. VII. p. 495; Stark’s “Biographia Scotica”;
_Philosophical Magazine_, Vol. XIII. pp. 386–394 (Biogr.
Memoir); Aikin’s “General Biography,” London, 1813, Vol.
VIII; Dr. Gleig in _Anti-Jacobin Magazine_ for 1802, Vol. XI;
Chalmer’s “Biographical Dictionary,” London, 1816, Vol. XXV; Dr.
Thomas Young, “Course of Lectures,” London, 1807, Vol. II. pp.
438, 444.

=A.D. 1793.=--Prof. Georg. Fred. Hildebrandt of Erlangen (1764–1816), makes important observations relative to the influence of form and of substance upon the electric spark. He finds, among other results, that an obtuse cone with an angle of fifty-two degrees gives a much more luminous spark than one with an angle of only thirty-six degrees; that the greatest sparks are given by conical pieces of regulus of antimony and the least by tempered steel; also, that when the spark is _white_ by taking it with a metallic body, it will, under the same circumstances, be _violet_ if taken with the finger; that if the spark is taken with ice or water, or a green plant, its light will be red, and, if it is taken with an imperfect conductor, such as wood, the light will be emitted in faint red streams.

REFERENCES.--Biography in fifth ed. of “Lehrbuch der Physiologie
des Mens. Koerpers,” Erlangen, 1817; “Encyl. Britannica,” Vol.
VIII, 1855, pp. 544, 545; “Biog. Générale,” Vol. XXIV. pp.
671–672; Ersch und Gruber, “Allgem. Encyklopædie.”

=A.D. 1794.=--Read (John), mathematical instrument maker, at the Quadrant, in Kingsbridge, Hyde Park, gives, in his “Summary View of the Spontaneous Electricity of the Earth and Atmosphere,” the result of a very elaborate series of observations, which he continued almost hourly between the years 1791 and 1792. Of 987 trials, he found that 664 gave indications of positive electricity, and out of 404 trials made during twelve months, the air was positively electrical in 241, negatively in 156, and insensible in only seven observations. He also found the vapour near the ground, in the act of condensing into dew, always highly electric.

He made many observations upon the electricity of vegetable bodies, which were afterward developed by M. Pouillet, and it was also Mr. Read who introduced a new hand-exploring instrument as well as an improved fixed thunder rod for collecting atmospherical electricity. These are described at p. 608 of the eighth volume of the 1855 “Encyclopædia Britannica.”

According to Mr. Wilkinson (“Elements of Galvanism,” etc., London, 1804, Vol. II. p. 344), Mr. Read was the first to apply the apparatus called the condenser to the electroscope in order that it should evince small intensities of electricity. He says: “The very minute portion of the fluid given out by the single contact of two different metals, does not produce any disturbance of the gold leaves; but when several minute portions are accumulated, a separation of the leaves takes place. The electroscope, in its simple state, will be as much charged the first time as if the contact had been made a thousand times, and cannot therefore acquire a greater quantity of the fluid than suffices to place it _in equilibrio_ with the metallic plates. This portion being inadequate to the production of any divergency of the leaves, Mr. Read applied the principle of the electrical doubler to the above instrument, by which means he was enabled to charge an intervening plate of air. By thus accumulating every minute portion of the fluid imparted through the metallic plate, and by apparently condensing and increasing its intensity, he ultimately succeeded in producing marked signs of disturbance.”

REFERENCES.--_Philosophical Transactions_ for 1791, p. 185; for
1792, p. 225; for 1794, pp. 185, 266: also Hutton’s abridgments,
Vol. XVII. pp. 52, 207, 423; “Bibl. Britan.,” Vol. II, 1796,
p. 209; Vol. III, 1796, p. 272; Vol. X, an. vii. p. 283;
Cavallo, “Nat. Phil.,” 1825, Vol. II. p. 226; Young’s “Course of
Lectures,” Vol. I. p. 714; Ed. Peart, “On Electric Atmospheres
...” Gainsboro’, 1793; “Eng. Ency.,” “Arts and Sciences,” Vol.
III. p. 805; Thomas Thomson, “Outline of the Sciences,” 1830, p.
446; _Journal de Physique_ for 1794, Vol. XLV. p. 468.

=A.D. 1794.=--Chladni (Ernst Florens Friedrich), founder of the theory of acoustics, publishes “The Iron Mass of Pallas,” etc. (“Ueber den Ursprung der von Pallas ...”), giving a list of recorded cases of the fall of meteorites or aerolites and all the important accounts of such that he was able to collect. As Prof. Alexander Herschel informs us, in his lecture, delivered (1867) before the British Association at Dundee, Chladni conceived that a class of cosmical bodies exists in all parts of the solar system, each forming by itself a peculiar concourse of atoms, and that the earth from time to time encounters them, moving with a velocity as great as its own, and doubtless in orbits of very various eccentricity around the sun. Prof. Muirhead says that through their exceeding great velocity, which is increased by the attraction of the earth and the violent friction of the atmosphere, a strong electricity and heat must necessarily be excited, by which means they are reduced to a flaming and melted condition, and great quantities of vapour and different kinds of gases are thus disengaged, which distend the liquid mass to a monstrous size, until, by still further expansion of these elastic fluids, they must at length explode (Chladni’s hypothesis in “Enc. Brit.,” article “Meteorolite”).

Humboldt gives (“Cosmos,” London, 1849, Vol. I. p. 104, note) the following upon the same subject, taken from Biot’s “Traité d’Astronomie Physique,” third edition, 1841, Vol. I. pp. 149, 177, 238, 312: “My lamented friend Poisson endeavoured in a singular manner to solve the difficulty attending an assumption of the spontaneous ignition of meteoric stones at an elevation where the density of the atmosphere is almost null. These are his words: ‘It is difficult to attribute, as is usually done, the incandescence of aerolites to friction against the molecules of the atmosphere, at an elevation above the earth where the density of the air is almost null. May we not suppose that the electric fluid, in a neutral condition, forms a kind of atmosphere, extending far beyond the mass of our own atmosphere, yet subject to terrestrial attraction, although physically imponderable, and consequently following our globe in its motion?’ According to his hypothesis, the bodies of which we have been speaking would, on entering this imponderable atmosphere, decompose the neutral fluid by their unequal action on the two electricities, and they would thus be heated, and in a state of incandescence, by becoming electrified” (Poisson, “Rech. sur la Probabilité des Jugements,” 1837, p. 6).

The theories advanced by Chladni were confirmed four years later by Brandes and Benzenberg at Göttingen, and, during the month of April 1809, he inserted a “Catalogue of Meteors” in the “Bulletin de la Société Philomathique,” which was followed by a paper on “Fiery Meteors” published at Vienna during 1819.

In his “Traité d’Acoustique,” Chladni treats of the line of experiments to which he was led, as well by the discovery of Lichtenberg’s electrical figures (see A.D. 1777, and Tyndall, “Sound,” Lecture IV), an account of which latter appeared in the “Mémoires de la Société Royale de Göttingen,” as through the suggestions made him by Lichtenberg himself during the year 1792 relative to the origin of meteors. The results of Chladni’s researches concerning the last named appeared in a Memoir published at Leipzig during 1794, translated by M. Eugène Coquebert Mombret for Vol. V of the _Journal des Mines_.

It may here be properly added that, in one of the editions of his “Lectures on Sound,” Prof. Tyndall gives a portrait of Chladni and quotes a letter received from Prof. Weber wherein he says: “I knew Chladni personally. From my youth up he was my leader and model as a man of science, and I cannot too thankfully acknowledge the influence which his stimulating encouragement during the last years of his life had upon my own scientific labours.”

REFERENCES.--Quetelet (Lambert A. J.) in “Cat. Sc. Pap. Roy.
Soc.,” Vols. V, VI, VIII; “Mém. de l’Acad. Roy. de Brux.,”
1830–1842; “Annali” of Ambroglio Fusinieri for 1854; “Phil.
Mag.,” 1851; Secchi (Angelo) in “Cat. Sc. Pap. Roy. Soc.,”
Vols. V, VIII; “Bull. Meteor. dell Osservat.,” 1862, 1866,
1867; Humboldt’s “Cosmos,” London, 1849, Vol. I. p. 104 (M.
Schreiber), pp. 113, 114 (M. Capocci), also pp. 105, 108, 110,
121, and the entire “Review of Natural Phenomena,” with all
the important references and notes thereunto attached. See
likewise Peter Simon Pallas (_Phil. Trans._ for 1776 and “Act.
Acad. Petrop.,” I for 1778); Chladni’s “Uber ... elektricität
einer Katze,” Jena, 1797; J. Acton and Capel Lofft, in _Phil.
Mag._, Vol. LI. pp. 109, 203; A Seguin, _Phil. Mag._, Vol.
XLIV. p. 212; Houzeau et Lancaster, “Bibl. Gén.,” Vol. II. pp.
714, 762, for étoiles, filantes et météorites; F. B. Albinus,
“Specimen,” etc., 1740; Voigt’s “Magaz.,” I, 1797; Schweigger’s
_Journal_, XLIII, 1825; H. Atkinson, “On Hypotheses,” etc.
(_Phil. Mag._, Vol. LIV. p. 336); Karstner, _Archiven_, Vol.
IV; F. C. Von Petersdorff in “Great Divide”; Pierre Prevost
and others in Poggendorff’s _Annalen_, Vols. II, VI and VII;
Arago, “Annuaire pour 1826”; “The fall of Meteorites in Ancient
and Modern Times” (“Sc. Progress,” Vol. II. N.S., pp. 349–370:
numerous references given by Prof. H. A. Miers; “A Century of
the Study of Meteorites,” by Dr. Oliver C. Farrington in “Pop.
Sc. Monthly,” Feb. 1901, or the Report of Smiths. Instit.
for 1901, pp. 193–197; _Phil. Mag._, Vol. IV. p. 332; “Cat.
Sc. Papers ... Roy. Soc.,” Vol. I. pp. 916–918; D. Avelloni
“Lettera,” etc., Venezia, 1760; Martin H. Klaproth’s different
memoirs published at Berlin 1795–1809; Joseph Izarn, “Lithologie
Atmosphérique”; J. Murray (_Phil. Mag._, Vol. LIV. p. 39);
beside Chladni’s works in conjunction with Karl F. Anton von
Schreibers, Wien, 1819 and 1820, and with Messrs. Steininger
and Næggerath, London, 1827 (Schweigger’s _Journal_, N.R., XVI.
385, and _Phil. Mag._, Vol. II. p. 41, also Vol. IV. p. 332).
For a very interesting account, see “A description of the great
Meteor which was seen on the 6th of March 1715–1716, sent in a
letter ... to R. Danuye ...” London, 1723 (_Phil. Trans._ for
1720–1721, Vol. XXXI), by Roger Cotes (1682–1716), of whom Sir
Isaac Newton entertained so high an opinion as to frequently
remark: “_If Mr. Cotes had lived, we had known something_”
(“Biographia Philosophica,” pp. 512–516; English Encycl.,
“Biography,” Vol. II. p. 401). Other exceedingly interesting
accounts of aerolites are to be found, more particularly in
Frederic Petit’s works, published at Toulouse, in Bigot de
Morogue’s “Catalogue,” London, 1814, and in the _Phil. Mag._,
Vols., XVII, XX, XXVIII, XXXII, XXXVI, XLIII, XLVI, XLVIII, L,
LIII, LIV, LVI-LIX, LXII. While treating of this subject, it
may be well to add here that up to the year 1887 diamonds were
not known to exist in meteorites. In a very remarkable paper by
Prof. A. E. Foote, read before the Geological section of the
Am. Asso. Adv. Sci., at its meeting in Washington, he described
having, during the month of June 1891, explored Crater Mountain
(Cañon Diablo), 185 miles north of Tucson, Ariz., where he
found some extraordinary specimens. The extreme hardness of one
of these attracted particular attention, and upon carefully
examining it he discovered in some of the cavities many small
black diamonds as well as a white diamond one-fiftieth of an
inch in diameter. This is said to be the most extensive find of
the kind yet made.

=A.D. 1794.=--Mr. J. Churchman publishes his improved “Magnetic Atlas or Variation Charts of the whole terraqueous globe,” etc., which Sir John Leslie subsequently pronounced the most accurate and complete hitherto made. The charts preceding it worthy of note were those of Dr. Halley (see A.D. 1683), of Mountaine and Dodson, in 1744 and in 1756, of Wilcke, in 1772, and of Lambert, in 1779. In his charts, Churchman refers variation lines to two poles, one of which he places, for the year 1800, in lat. 58° N. and long. 134° W. of Greenwich, while the other pole is in lat. 58° S. and long. 165° E. of Greenwich. He supposes the northern pole to revolve in 1096 years and the southern one in 2289 years (“Ency. Brit.,” 1857, Vol. XIV. p. 49).

REFERENCES.--Churchman’s letters to Cassini, Phila., 1788, and
his “Explanation of the Magn. Atlas ...” 1790; Harris, “Rudim.
Mag.,” Part III. p. 101; “Bibl. Britan.,” Vol. II. 1796, p. 325
(atlas); Becquerel, “Traité d’Electr. et de Magn.,” Paris, 1856,
III. p. 140.

=A.D. 1794.=--M. Reusser Reiser, of Geneva, addresses a letter to the “Magazin für das Neueste aus der Physik” of Johann Heinrich Voigt (Vol. IX. part i. p. 183), describing the construction of “a new species of electric letter post” (“Schreiben an den herausgeber”) in the following words: “... on an ordinary table is fixed, in an upright position, a square board, to which a glass plate is fastened. On this plate are glued little squares of tinfoil, cut after the fashion of luminous panes, and each standing for a letter of the alphabet. From one side of these little squares extend long wires, enclosed in glass tubes, which go underground to the place whither the despatch is to be transmitted. The distant ends are there connected to tinfoil strips, similar ... to the first, and, like them, each marked by a letter of the alphabet; the free ends of all the strips are connected to one return wire, which goes to the transmitting table. If, now, one touches the outer coating of a Leyden jar with the return wire, and connects the inner coating with the free end of that piece of tinfoil which corresponds to the letter required to be indicated, sparks will be produced, as well at the near as at the distant tinfoil, and the correspondent there watching will write down the letter....”

Reusser also suggested calling the attention of the correspondent by firing an electrical pistol through the spark; to him, therefore, belongs the credit of having first clearly indicated the use of a special call for the telegraph.

REFERENCES.--Vail’s “History,” p. 121; Voigt’s “Magazin ...”
Vol. VII. part ii. p. 57; Shaffner, “Manual,” pp. 133, 134;
Forster’s “Bauzeitung,” 1848, p. 238; Ed. Highton, p. 38;
Sabine, p. 11; “Appleton’s Encycl.,” 1871, Vol. XV. p. 335;
Reiser, “Der El. Würfel,” Gotha, 1791; _Comptes Rendus_, Tome
VII for 1838, p. 80.

=A.D. 1794.=--Prof. Boeckmann improves upon Reusser’s idea, and does away with the thirty-six plates and the seventy-two wires which the latter is believed to have employed. As Dr. Schellen expresses it, he used “the sparks passing at the distant station, employing only two wires, through which first one and then, after certain intervals, more sparks are combinedly grouped” in a way to indicate particular letters. Like Reusser, he made use of the pistol as a call signal.

REFERENCES.--Zetzsche, “Geschichte der Elektrischen
Telegraphie,” p. 32; Boeckmann, “Versuch über Telegraphie und
Telegraphen,” Carlsruhe, 1794, p. 17; “El. Magn. Teleg.,” 1850,
p. 46; Gren’s _Journal der Physik_, Vol. I for 1790; “Neue
Abhandl. der Bairischen Akad. Philos.,” Vol. III.

=A.D. 1794.=--Edgeworth (Richard Lovell), an able English mechanical philosopher, better known as the father and literary associate of Maria Edgeworth, introduces his _tellograph_ (contraction of the word _telelograph_), “a machine describing words at a distance,” which originated in a wager relative to the prompt transmission of racing news from Newmarket to London. It consisted merely of four pointers, in the form of wedges or isosceles triangles, placed upon four portable vertical posts and the different positions of which were arranged to represent letters and numbers.

Edgeworth claimed to have made experiments, as early as 1767, with an ordinary windmill, the arms and sails of which were arranged in different positions to indicate the several letters of the alphabet.

REFERENCES.--Edgeworth’s Letter to Lord Charlemont on the
Tellograph, also his “Essay on the Art of Conveying Secret and
Swift Intelligence,” Dublin, 1797, republished in Vol. VI of the
_Trans. of the Royal Irish Academy_; “Appleton’s Encycl.,” 1871,
Vol. XV. p. 334.

A.D. 1795.--Lord George Murray, of England, submits to the Admiralty his six-shutter telegraph, an improvement upon Chappe’s original plan. Each of the six octagonal shutters was made to turn inside of two frames at different angles upon its own axis, thus affording sixty-three separate and distinct signals. By its means, information was transmitted from London to Dover in seven minutes, and it answered nearly all the requirements of the Admiralty up to the year 1816, when it was superseded by the semaphore of Rear Admiral Popham. Murray’s method was, however, useless during foggy weather, when relays of horses had to be employed for conveying the news.

REFERENCES.--English Encyclopædia, “Arts and Sciences,” Vol.
VIII. p. 66; Tomlinson’s “Telegraph”; Turnbull, _El. Mag. Tel._,
1853, p. 18; “Penny Ency.,” Vol. XXIV. p. 147.

=A.D. 1795.=--Salvá (Don Francisco), a distinguished Spanish physician, reads a memoir, before the Academy of Sciences of Barcelona, from which the following is extracted: “... with twenty-two letters, and even with only eighteen, we can express with sufficient precision every word in the language, and, thus with forty-four wires from Mataro to Barcelona, twenty-two men there, each to take hold of a pair of wires, and twenty-two charged Leyden jars here, we could speak with Mataro, each man there representing a letter of the alphabet and giving notice when he felt the shock.... It is not necessary to keep twenty-two men at Mataro nor twenty-two Leyden jars at Barcelona, if we fix the ends of each pair of the wires in such a way that one or two men may be able to discriminate the signals. In this way six or eight jars at each end would suffice for intercommunication, for Mataro can as easily speak with Barcelona as Barcelona with Mataro ... or the wires can be rolled together in one strong cable ... laid in subterranean tubes, which, for greater insulation, should be covered with one or two coats of resin.”

He is said to have approved of the use of luminous panes as indicated by Reusser; to have also suggested, as early as December 16, 1795, the idea of a _submarine telegraphic cable_ carrying several conductors, and to have proposed, at the same period, the laying of a cable between Barcelona and Palma in the island of Majorca.

In 1798, Salvá constructed a single wire telegraphic line between Madrid and Aranjuez, a distance of twenty-six miles, through which the signals were transmitted in the shape of sparks from Leyden jars. This is the line which is credited to Augustin de Bétancourt, a French engineer, by Alexander Von Humboldt, in a note at p. 14 of Gauss and Weber’s _Resultate_, etc., for the year 1837.

On the 14th of May 1800, and on the 22nd of February 1804, Salvá communicated to the Academy of Sciences at Barcelona two papers on galvanism applied to electricity, wherein he shows that a cheaper motive power is produced by the electricity of a number of frogs, and proposes a telegraphic apparatus in conjunction with the voltaic column which is illustrated and described at pp. 224 and 225 of Fahie’s “History of Telegraphy.” From the latter the following is taken: “This illustrious Spanish physician (Salvá) was therefore the first person who attempted to apply electricity dynamically for the purpose of telegraphing. It is, says Saavedra, not without reason, I must confess, notwithstanding my cosmopolitan opinions on scientific questions, that _the Catalans hold Salvá to be the inventor of electric telegraphy_. With documents as authentic as those which I have seen with my own eyes in the very hand writing of this distinguished professor (which documents are at this present moment to be found in the library of the Academy of Sciences of Barcelona) it is impossible for any author to henceforth deny, even if others did precede Salvá in telegraphic experiments with static electricity, that no one preceded him in the application of the docile electro-dynamic fluid to distant communications.”

REFERENCES.--_Comptes Rendus_, séance, 1838; Memorial of Joseph
Henry, 1880, p. 224; Ed. Highton, the _El. Tel._, 1852, pp.
38 and 43; “Appleton’s Encyclopædia,” 1871, Vol. XV. p. 335;
_De Bow’s Review_, Vol. XXV. p. 551; Voigt’s _Magazin_, etc.,
Vol. XI. part iv. p. 61; _Sc. Am. Supp._, No. 547, p. 8735, and
No. 384, p. 6127; Biography in Saavedra’s _Revista_, etc., for
1876; Noad’s _Manual_, pp. 747 and 748; Shaffner, _Manual_,
p. 135; Turnbull, _El. Mag. Tel._, 1853, pp. 21, 22, 220; Du
Moncel, _Exposé_, Vol. III; “Edinburgh Encyclopædia,” London,
1830, Vol. VIII. p. 535; “Gazette de Madrid” of November 25,
1796; “Mémoires de l’Institut,” Vol. III and “Bulletin de la
Soc. Philom.,” An. VI for the new telegraph of MM. Bréguet and
Bétancourt, and for the Report made thereon by MM. Lagrange,
Laplace and others.

=A.D. 1795.=--Ewing (John), D.D., Provost of the University of Pennsylvania and one of the founders of the American Philosophical Society, makes a compilation of his course of lectures on natural experimental philosophy, which is subsequently revised for the press by Prof. Robert Patterson.

He devotes much attention to atmospheric electricity, detailing the Franklinian theory, and, besides reporting upon the hypotheses advanced by Henry Eales (at A.D. 1755), as well as treating of the attraction of magnetism, he gives a very interesting account of experiments with the _torpedo_ and the _gymnotus electricus_. He says that Mr. Walsh found the _torpedo_ “possessed of the power of shocking only in two parts of its body, directly opposite to each other and near to the head. A spot on the back and another on the belly opposite to the former being of a different colour led him to make the experiment, and he found that the electrical virtue was confined to these, and that any other part of the fish might be handled, without receiving a shock, while it was out of the water. Either of these places separately might be handled without the shock being received until a communication between them was formed. This makes it appear probable that the same may also be the case with the Guiana eel. One of these spots must therefore be always in the positive and the other in the negative state; or, rather, they are both generally in the natural state, until, by an effort of the fish’s will, they are suddenly put into different states, as we frequently found that the hand might be in the water, which formed the communication, without receiving any shock. This cannot be the case with the Leyden bottle when charged, which suddenly discharges itself upon forming the communication. Whether there be any electric atmosphere round these spots in the _torpedo_ we cannot tell, as we had no opportunity of examining this matter in the eel, nor have we heard whether Mr. Walsh made any experiments for ascertaining this.”

ELECTRICITY OF THE ATMOSPHERE

The investigations of John Ewing concerning atmospheric electricity were in reality quite extensive. He not only repeated the experiments of Franklin, but he examined thoroughly those of other scientists in the same channel, especially the investigations of Henry Eeles, which will be found detailed in the latter’s “Trinity College Lectures” as well as in his “Philosophical Essays,” London, 1771.

For a very interesting historical review of theories as to the origin of atmospherical electricity, it would be well to consult M. A. B. Chauveau’s article in “Ciel et Terre,” Bruxelles, March 1, 1903, and also Humboldt’s “Cosmos,” London, 1849, Vol. I. pp. 342–346. In the last-named work are cited: Arago, “Annuaire,” 1838, pp. 246, 249–266, 268–279, 388–391; Becquerel, “Traité de l’Electricité,” Vol. IV. p. 107; De la Rive, “Essai Historique,” p. 140; Duprez, “Sur l’électricité de l’air,” Bruxelles, 1844, pp. 56–61; Gay-Lussac, “Ann. de Ch. et de Phys.,” Vol. VIII. p. 167; Peltierin, “Ann. de Chimie,” Vol. LXV. p. 330, also in “Comptes Rendus,” Vol. XII. p. 307; Pouillet, “Ann. de Chimie,” Vol. XXXV. p. 405.

------+-----------------+-------------------------------+--------------------------- | | | Date | Name | Experiments | References | | | ------+-----------------+-------------------------------+--------------------------- 1751 |Franklin |Effects of lightning |Phil. Trans., xlvii. p. 289 ------+-----------------+-------------------------------+--------------------------- 1751 |Mazeas |Kite experiments independently |Phil. Trans., 1751–1753 | | of Franklin | ------+-----------------+-------------------------------+--------------------------- 1752 |Nollet |Theory of Electricity |Recher. sur les causes, | | | 1749–1754 | | |Lettres sur l’élect., 1753, | | | 1760, 1767, 1770 ------+-----------------+-------------------------------+--------------------------- 1752 |Watson |Electricity of clouds |Phil. Trans., 1751, 1752 ------+-----------------+-------------------------------+--------------------------- 1752 |De Lor and Buffon|Iron pole 99 ft. high, mounted |Letter of Abbé Mazeas, | | on a cake of resin 2 ft. sq.,| dated St. Germain, | | 3 in. high, Estrapade, May | May 20, 1742 | | 18, 1752 | ------+-----------------+-------------------------------+--------------------------- 1752 |D’Alibard |Sparks from thunder clouds, 40 |Mem. l’Acad., r. des | | ft. pole in garden at Marly, | Sci., May 13, 1762 | | also wooden pole 30 ft. high,| Hist. Abrégée, 1776 | | at Hôtel de Noailles | ------+-----------------+-------------------------------+--------------------------- 1752 |Le Monnier |Observations of air charge |Mém. de Paris, 1752, | | | pp. 8, 233 ------+-----------------+-------------------------------+--------------------------- 1752 |De Romas |Observations of air charge; |Mém. Sav. Etrangers, | | kite experiments | 1752, and Mém. de | | | Math., 1755, 1763 ------+-----------------+-------------------------------+--------------------------- 1752 |Mylius, Ch. |Observations of air charge |“Nachrichten,” Berlin, 1752 | | | ------+-----------------+-------------------------------+--------------------------- 1752 |Kinnersley |Observations of air charge |Franklin’s Letters, Phil. | | | Trans., 1763, 1773 ------+-----------------+-------------------------------+--------------------------- 1752 |Ludolf and Mylius|Observations of air charge |Letter to Watson ------+-----------------+-------------------------------+--------------------------- 1753 |Richman |Electrical gnomon |Phil. Trans., 1753 ------+-----------------+-------------------------------+--------------------------- 1753 |Canton |Electricity of clouds |Franklin’s letters and | | | Phil. Trans., 1753 ------+-----------------+-------------------------------+--------------------------- 1753 |Beccaria, C.B. |Systematic observations with |Lett. dell’ Elet. Bologna, | | an electroscope | 1758 ------+-----------------+-------------------------------+--------------------------- 1753 |Wilson |Experiments |Phil. Trans., 1753, p. 347 ------+-----------------+-------------------------------+--------------------------- 1754 |Lining |Kite experiments |Letter to Chas. Pinckney ------+-----------------+-------------------------------+--------------------------- 1755 |Le Roy |Experiments |Mém. de Paris, 1755 ------+-----------------+-------------------------------+--------------------------- 1756 |Van Musschenbroek|Kite experiments |Intro. ad Phil. Nat., 1762 ------+-----------------+-------------------------------+--------------------------- 1759 |Hartmann |Origin of electricity |Verbesseter ... Blitzes | | | (_Hamb. Mag._ vol. xxiv.) ------+-----------------+-------------------------------+--------------------------- 1769 |Cotte |Memoirs on meteorology |Journ. Phys., xxiii., 1783 | | | Mém. Paris, 1769–1772 ------+-----------------+-------------------------------+--------------------------- 1772 |Ronayne |Fog observations |Phil. Trans., 1772, p. 137 ------+-----------------+-------------------------------+--------------------------- 1772 |Henley |Quadrant electrometer |Phil. Trans., 1772–1774 ------+-----------------+-------------------------------+--------------------------- 1775 |Cavallo |Fogs, snow, clouds and rain; |Treatise on Elect., 1777 | | kite experiments | ------+-----------------+-------------------------------+--------------------------- 1784 |De Saussure |Observations |“Voyages dans les Alpes,” | | | Geneva, 1779–1796 ------+-----------------+-------------------------------+--------------------------- 1786–7|Mann |Daily observations with an |Ephémer. Météorol. of the | | electrical machine, timing | Mannheim Society, | | the revolutions to produce a | 1786–1792 | | given spark with a record of | | | the weather | ------+-----------------+-------------------------------+--------------------------- 1788 |Volta |New electroscope |Lettere Sulla Meteor, | | | 1788–1790 ------+-----------------+-------------------------------+--------------------------- 1788 |Crosse |Experiments with collectors |Gilb. Ann., Bd. 41, s. 60 ------+-----------------+-------------------------------+--------------------------- 1791 |Read |Insulation and conductors |Phil. Trans., 1791 and | | | Summary, 1793 ------+-----------------+-------------------------------+--------------------------- 1792 |Von Heller |Observations |Gren, “_Neues Journ. der | | | Phys._,” vol. ii. 1795 | | | and vol. iv. 1797 ------+-----------------+-------------------------------+--------------------------- 1792 |Schubler |Observations with weather rod |J. de Phys., lxxxiii. 184 ------+-----------------+-------------------------------+---------------------------

An attractive table, which we are permitted to rearrange and reproduce here, giving a _résumé_ of references to some of the most noted experiments of the chief investigators from the time of Franklin to the end of the eighteenth century, was made up by Mr. Alex. McAdie and first appeared in the “Amer. Meteor. Journal.” Mr. McAdie says that a detailed history of most of Franklin’s co-labourers will be found in the accounts given by Exner,[53] Hoppe,[54] Mendenhall,[55] Elster and Geitel[56] as well as by himself,[57] and that in making up this table he has passed over Peter Collinson, of London, who introduced to the notice of the Royal Society the experiments of Franklin, and the three less-known workers--J. H. Winkler, who wrote in 1746 on the electrical origin of the weather lights; Maffei, 1747; and Barberet, 1750.

=A.D. 1795.=--The telegraphs of the Rev. J. Gamble, Chaplain to the Duke of York, consisted either of five boards placed one above the other or of arms pivoted at the top of a post upon one axis and capable of producing as many signals as there are permutations in the number five, all of the combinations being possible at equal angles of forty-five degrees. His doubts as to the practicability of employing electricity “as the vehicle of information” are fully expressed at p. 73 of his “Essay on the Different Modes of Communicating by Signal,” etc., London, 1797.

REFERENCES.--J. Gamble, “Observations on Telegraphic
Experiments,” etc.; Article “Telegraph” in Tomlinson’s “Encyl.
of Useful Arts”; “Penny Ency.,” Vol. XXIV. pp. 147 and 148;
“English Cyclopædia,” “Arts and Sciences,” Vol. VIII. p. 66.

=A.D. 1795.=--Garnet (John), proposes a telegraph consisting of only one bar moving about the centre of a circle, upon which latter the letters and figures are inscribed. On placing corresponding divisions, by means of wires, before the object glass of the telescope the coincidence of the two radii or of the arm would point out the letter intended to be repeated. As this plan proved impracticable for long distances, it did not come into general use (“Emporium of Arts and Sciences,” Phila., 1812, Vol. I. p. 293).

=A.D. 1795.=--Wells (Charles William), a physician, native of South Carolina but practising in England and a F.R.S., publishes in the _Phil. Trans._ a paper on the influence which incites the muscles of animals to contract in Galvani’s experiments. Therein he was the first to demonstrate that voltaic action is produced through charcoal combined with another substance of different conducting power, and this he did by causing noticeable convulsions in a frog through the combination of charcoal and zinc. (See “Ency. Met.,” Vol. IV. pp. 220, 221, for the experiments of both Dr. Wells and Dr. Fowler.) Fahie states that Davy subsequently constructed a pile which consisted of a series of eight glasses containing well-burned charcoal and zinc, using a red sulphate of iron solution as the liquid conductor. It is said this series gave sensible shocks and rapidly decomposed water and that, compared with an equal and similar series of silver and zinc, its effects were much stronger. (See Priestley’s discovery of the electrical conductibility of charcoal at A.D. 1767, and the description of Davy’s charcoal battery in “Jour. Roy. Inst.” and _Nicholson’s Journal_, N. S., Vol. I. p. 144.)

His biographer, in the “Eng. Cyclop.,” says (Vol. VI. pp. 631–632) that his last work and the one upon which his reputation as a philosopher must rest, is his “Essay upon Dew,” published in 1814 (“Journal des Savants” for Sept. 1817), whilst J. F. W. Herschel remarks at p. 122 of his “Prel. Disc ... Nat. Phil.,” 1855: “We have purposely selected this theory of dew, first developed by the late Dr. Wells, as one of the most beautiful specimens we can call to mind of inductive experimental inquiry lying within a moderate compass....”

REFERENCES.--Wells’ biography in the “English Cyclopædia,”
Vol. VI. p. 631; _Phil. Trans._ for 1795, p. 246; Hutton’s
abridgments of the _Phil. Trans._, Vol. XVII. p. 548; Fahie’s
“History,” etc., pp. 201 and 202; “Aristotle on Dew”
(Poggendorff, _Geschichte der Phys._, 1879, p. 42); Luke
Howard, “On the Modification of Clouds ...” London, 1803; C. H.
Wilkinson, “Elements of Galvanism,” etc., London, 1804, Vol. I.
pp. 162–165 and Vol. II. p. 329.

=A.D. 1796.=--Gregory (George), D.D., F.R.S., Vicar of Westham, a miscellaneous writer of Scotch origin, for many years editor of the “New Annual Register,” is the author of “Economy of Nature,” etc., of which the second and third editions, considerably enlarged, appeared respectively in 1798 and 1804.

In the first volume of the last-named edition (Book I. chap. vi. pp. 35–54) he treats of natural and artificial magnets and of magnetic powers and theories of magnetism, while the whole of Book IV. (chaps. i.-viii. pp. 299–386) is devoted to the history of and discoveries relative to electricity, its principles and theories, as well as to electrical apparatus and electrical phenomena and to galvanism or animal electricity.

Gregory is also the author of “Popular Lectures on Experimental Philosophy, Astronomy and Chemistry; Intended Chiefly for the Use of Students and Young Persons,” 2 vols., 12 mo, published in London 1808–1809, one year after Gregory’s death.

It was the perusal of the latter work which led Joseph Henry to embrace a scientific career, just as the reading of “Mrs. Marcet’s Conversations on Chemistry” had induced Michael Faraday to enter the field in which he afterward became so highly distinguished. Prof. Asa Gray, in his Biographical Memoir of Henry, says that Gregory’s work alluded to is an unpretending volume but a sensible one, and that it begins by asking three or four questions, such as these: “You throw a stone, or shoot an arrow into the air; why does it not go forward in the line or direction that you give it? Why does it stop at a certain distance and then return to you?... On the contrary, why does flame or smoke always mount upward, though no force is used to send them in that direction? And why should not the flame of a candle drop toward the floor when you reverse it, or hold it downward, instead of turning up and ascending into the air?... Again, you look into a clear well of water and see your own face and figure as if painted there? Why is this? You are told that it is done by reflection of light. But what is reflection of light?” As Prof. Gray remarks, young Henry’s mind was aroused by these apt questions, and allured by the explanations. He now took in a sense of what knowledge was. The door to knowledge opened to him, that door which it thence became the passion of his life to open wider. The above-named volume is preserved in Prof. Henry’s library, and bears upon a fly-leaf the following entry:

“This book, although by no means a profound work, has, under Providence, exerted a remarkable influence upon my life. It accidentally fell into my hands when I was about sixteen years old, and was the first work I ever read with attention. It opened to me a new world of thought and enjoyment; invested things before almost unnoticed with the highest interest; fixed my mind on the study of nature, and caused me to resolve at the time of reading it, that I would immediately commence to devote my life to the acquisition of knowledge. J. H.” (See Prof. A. M. Mayer, “Eulogy of Joseph Henry,” Salem, 1880, pp. 29–30; “Smithsonian Report,” 1878, pp. 145, 146.)

REFERENCES.--_Gentleman’s Magazine_, Vol. LXVII. p. 415; Beloe’s
“Sexag.,” II. 128; “Living Authors” (1798), I. p. 225.

=A.D. 1797.=--Bressy (Joseph), French physician and able chemist, remarks, in his “Essai sur l’électricité de l’eau,” that the electric fluid is composed of three beams (_rayons_, i. e. rays, gleams, or sparks), vitreous, resinous and vital; that three principal agents exist in nature, viz. the air, isolating body; the water, conducting body, and movement, determining action; that vapours resolve themselves into clouds merely because friction enables the electric fluid to seize upon the aqueous molecules, and that, in water, the hydrogen is maintained in the form of gas by the electric fluid, while the oxygen becomes gaseous under influence of the caloric.

REFERENCES.--Larousse, “Dict. Univ.,” Vol. II. p. 1236;
Delaunay, “Manuel,” etc., 1809, pp. 15, 16.

=A.D. 1797.=--Treméry (Jean Louis), a French mining engineer, communicates his observations on elliptic magnets through Bulletin No. 6 of the “Société Philomathique” as well as through the sixth volume of the _Journal des Mines_.

His observations on conductors of electricity and on the emission of the electric fluid appear at p. 168 Vol. XLVIII of the _Jour. de Phys._, and in “Bull. de la Soc. Philom.,” No. 19, while his views in opposition to the two-fluid theory are to be found in Bulletin No. 63 of the last-named publication as well as in _Jour. de Phys._, Vol. LIV. p. 357.

REFERENCES.--Poggendorff, Vol. II. p. 1131; John Farrar, “Elem.
of Elec.,” etc., p. 120.

=A.D. 1797.=--Pearson (George), English physician and chemist, communicates to the Royal Society a very interesting paper entitled, “Experiments and Observations made with the view of ascertaining the nature of the gas produced by passing electric discharges through water; with a description of the apparatus for these experiments.”

An abstract of the above appears in the _Phil. Trans._ for 1797, and a full transcript of it is to be found in _Nicholson’s Journal_, 4to, Vol. I. pp. 241–248, 299–305, and 349–355.

As Mr. Wilkinson has it, “Dr. Pearson supposes the decomposition of water by electricity to be effected by the interposition of the dense electric fire, between the constituent elements of the water, which he places beyond the sphere of attraction for each other, each ultimate particle of oxygen and hydrogen uniting with a determinate quantity of the electric fire to bestow on them their gaseous form. Hence the doctor supposes that the electric fire, after effecting the disunion, assumes the state of caloric.

“On the reproduction of water by the passage of an electric spark through a proportionate quantity of oxygen and hydrogen gases, Dr. Pearson ingeniously conjectures that by the influence of the electric flame the ultimate particles of these gases, the nearest to the flame, are driven from it in all directions, so as to be brought within the sphere of each other’s attractions. In one of these cases Dr. Pearson supposes that the caloric destroys the attraction, which in the other instance it occasions.

“It is with diffidence that I take on me to controvert the opinions of this very respectable physician; but I presume that the whole of the phenomena of the synthesis and analysis of water are more readily to be explained on the principles I have laid down than by the adoption of the mysterious terms of attraction and repulsion. By the operation of galvanism, water is more rapidly decomposed than by common electricity. In this operation there is no evolution of dense electrical fire, but merely a current of a small intensity of electricity acting permanently and incessantly. To reproduce water, a flame must be generated sufficient to kindle the contiguous portion of the hydrogen gas, then the next portion, and so on, the combustion being preserved by the presence of the oxygen gas. As these processes proceed with immense rapidity as soon as the gases are intermixed, so as to appear like one sudden explosion, the caloric of each of them being thus disengaged, their bases unite and constitute water.”

Dr. Pearson also made many interesting experiments to ascertain the effect of the application of galvanic electricity for the treatment of diseases, and Noad, who describes one of his successful operations, also details (“Manual,” pp. 343–349) the observations of many others in the same line, notably those of Drs. Apjohn, Majendie, Grapengieser and of Wilson Philip, Petrequin, Pravaz, Prevost and Dumas (_Jour. de Physiol._, Tome III. p. 207), as well as of Sarlandière and Dr. Golding Bird, besides giving the very important conclusions arrived at by Stefano Marianini.

REFERENCES.--“Some Account of George Pearson,” M.D., F.R.S.
(_Phil. Mag._, Vol. XV for 1803, p. 274); letter of Humboldt
to M. Loder (“Bibl. Germ.,” Vol. IV, Messidor, An. VIII. p.
301); William Van Barneveld, “Med. Elektricität,” Leipzig,
1787; C. H. Wilkinson, “Elements of Galvanism,” London, 1804,
2 vols. _passim_; Paragraph No. 328 of Faraday’s “Experimental
Researches,” J. N. Hallé, “Journal de Médecine de Corvisart,”
etc., Tome I, Nivose, An. IX. p. 351; “Annales de l’Electricité
Médicale” _passim_; H. Baker (_Phil. Trans._, Vol. XLV. p. 270);
“Jour. de la Soc. Philom.,” Messidor, An. IX; J. F. N. Jadelot,
“Expériences,” etc., 1799; M. Butet (“Bull. des Sc. de la Soc.
Philom.,” No. 43, Vendémiaire, An. IX); M. Oppermanno, “Diss.
Phys. Med.” (see J. G. Krunitz “Verzeichnis,” etc.); Andrieux,
“Mémoire ... maladies,” Paris, 1824; Lebouyer-Desmortiers
(Sue, “Hist. du Galv.,” Vol. II. p. 420, and _Jour. de Phys._,
Prairial, An. IX, 1801, p. 467); C. J. C. Grapengieser,
“Versuche den Galvanismus,” etc., Berlin, 1801 and 1802;
the works of J. Althaus, published in London and Berlin in
1859–1870; C. A. Struve’s works, published in Hanover and
Breslau, 1797–1805; F. L. Augustin’s works, published in Berlin,
1801–1803; Karl Friedrich Kielmeyer (Kielmaier), works published
at Tübingen (Poggendorff, Vol. I. p. 1253); Einhoff (Gilbert,
XII. p. 230); Francesco Rossi’s treatises on the application
of galvanism, published in 1809; Gilb. “Ann.,” Vol. XII. p.
450; _Jour. de Phys._, Vol. LII. pp. 391 and 467; Cuthbertson’s
letter in _Phil. Mag._, Vol. XVIII. p. 358; J. G. Anglade,
“Essai sur le Galvanisme,” etc. (Sue, “Hist. du Galv.,” Vol.
III. p. 73); Jacques Nauche, in _Phil. Mag._, Vol. XV. p. 368,
as well as in Poggendorff, Vol. II. p. 256, and throughout the
“Journal du Galvanisme.”

=A.D. 1797.=--In No. CCXXII of the _Reichsanzeiger_, a German publication, it is said that a certain person having an artificial magnet suspended from the wall of his study with a piece of iron adhering to it, remarked, for several years, that the flies in the room, though they frequently placed themselves on other iron articles, never settled upon the artificial magnet.

REFERENCES.--Cavallo, “Experimental Philosophy,” 1803, Vol. III.
p. 560, or the 1825 Philad. ed., Vol. II. p. 286.

=A.D. 1797–1798.=--Reinhold (Johann Christoph Leopold), while Bachelor of Medicine in Magdeburg, tendered for his theses, on the 16th of December 1797 and on the 11th of March 1798, two Latin dissertations on galvanism, one of which was offered concurrently with J. William Schlegel, then a medical student.

Numerous extracts from both the above very important papers, which treat extensively of galvanic experiments upon animals, vegetables, metals, etc., will be found at pp. 123–195, Vol. I of Sue’s “Histoire du Galvanisme,” Paris, 1802. Both dissertations review galvanism from its origin and make mention of many works which had not up to that time appeared in print.

In the first volume of his “Elements of Galvanism,” London, 1804, Mr. C. H. Wilkinson devotes the entire Chap. VIII (pp. 188–260) to Reinhold’s able review of galvanism, wherein are first cited Gardiner (author of “Observations on the Animal Economy”), Lughi, Klugel and Gardini as “anterior to the discovery of the doctrine of animal electricity.” Then follow accounts of their writings, as well as of those of Galvani and of Volta, “the Prince of Italian naturalists,” after which due mention is made, in their proper order, of the observations of Aldini, Valli, Fontana, Berlinghieri, Monro, Fowler, Corradori, Robison, Cavallo, Wells, Havgk, Colsmann, Creve, Hermestædt, Klein, Pfaff, Ackermann, Humboldt (letters to Blumenbach, Crell, Pictet and M. de Mons), Eschenmeyer, Achard, Grapengieser, Gren, Michaelis, Caldani, Schmuck, Mezzini, Behrends, Giulio, Ludwig, Webster, Vasco, Hebenstreit and others.