Chapter XXXII: Part II: for 1808 (1)

=A.D. 1806.=--On Oct. 16, Mr. Wm. Skrimshire, Jr., addresses from Wisbech a letter to Mr. Cuthbertson on the absorption of electric light by different bodies.

In this letter, which is given in full at pp. 281–283 of the fifteenth volume of _Nicholson’s Journal_, he says he was led to his experiments by the well-known fact that when the electric current is passed through a lump of sugar it makes the latter appear luminous. He tried many calcareous species, chalk, Kelton stone, the phosphate, nitrate, sulphates of lime, etc. etc., and he details some of the results obtained, the most interesting being that given by the sulphuret of lime, commonly called Canton’s phosphorus, which, he says, is, by the electric explosion, rendered the most luminous of all the substances tried.

=A.D. 1806.=--Heidmann (J. A.), physician at Vienna, publishes his “Theorie der Galvanischen Electricität ...” or “Theory of Galvanic Electricity deduced from Actual Experimentation” (London, 1807). This had been preceded by other important electrical reviews at Vienna during the years 1799, 1803 and 1804.

As stated by Guyton de Morveau, Heidmann has given us in the above the complete history of galvanic electricity--including the experiments and observations of Aldini, Arnim, Biot, Boeckman, Carminati, Cavallo, Creve, Davy, Fontana, Fowler, Gilbert, Haldane, Hallé, Helebrandt, Humboldt, Nicholson, Pepys, Pfaff, Reil, Reinhold, Ritter, Valli, Vassalli-Eandi, etc. etc.--together with the description of the construction and the relation of all parts of the galvanic pile, which is called by him a galvanic battery. Heidmann also gives an account of his many interesting experiments with frogs placed in different liquids as well as with the galvanic chain, and he reviews all the known phenomena presented by the voltaic pile.

REFERENCES.--“Annales de Chimie,” Vol. LXI. p. 70; _Phil. Mag._,
Vol. XXVIII. p. 97.

=A.D. 1806.=--Dr. Joseph Baronio of Milan constructs a galvanic pile composed exclusively of vegetable substances. He makes his discs, two inches in diameter, of beet roots (_bietola rossa_) and of walnut wood (_legno di noce_), the latter having been freed from all of its resinous substance by treatment in a solution of vinegar and cream of tartar. Through this pile, he produced convulsions in a frog by excitation with a leaf of _cochlearia_ (spoon wort or scurvy-grass).

REFERENCES.--“Annales de Chimie,” Vol. LVII. pp. 64–67; Vol.
LXII. p. 212; _Phil. Mag._, Vol. XXIII. p. 283; “Nota di
Brugnatelli sopra una pila di sostanze vegetabili,” Pavia, 1805
(“Am. di Chim. di Brugnatelli,” Vol. XXII. p. 301); Volta, in
_Giorn. Fis. Med._, Vol. II. p. 122.

=A.D. 1806.=--Sylvester (Charles), the author of the articles on “Galvanism and Voltaism” in Rees’ “Encyclopædia,” announces that he obtains muriatic acid from pure water by passing through it the galvanic current. Mr. Wollaston, however, asserts this cannot be done unless the current traverses some vegetable or animal substance containing that acid.

His first paper on the subject appeared in _Nicholson’s Journal_, 1806, Vol. XIV. pp. 94–98; in Gehlen’s _Journ. der Chemie_, Vol. II for 1806, pp. 152–153, and in Gilbert’s _Annalen der Physik_, Vol. XXV. pp. 107–112, 454–457. The paper following is entitled “Repetition of the Experiment in which Acids and Alkalies are Produced in Pure Water by Galvanism (no animal or vegetable matter, nor oxidable metal being present).”

REFERENCES.--_Nicholson’s Journal_, Vol. XV. pp. 50–52; Vol.
XXIII. pp. 258–260; Gehlen’s _Journal_, Vol. II, 1806, pp.
155–158. For his other papers, consult _Nicholson’s Journal_,
Vol. IX. p. 179; Vol. X. pp. 166–167; Vol. XIX. pp. 156–157;
Vol. XXVI. pp. 72–75; Gilbert’s _Annalen_, Vol. XXIII. pp.
441–447; “Roy. Soc. Catal. of Sc. Papers,” Vol. V. pp.
900–901; Sturgeon’s _Scientific Researches_, Bury, 1850, p.
153; Sir Humphry Davy’s lecture “On some chemical agencies of
electricity,” read Nov. 20, 1806; _Annales de Chimie_, Vol. LX.
p. 314; Vol. LXI. pp. 330–331; “Bibl. Britan.,” Vol. XXXIII,
1806, p. 324.

=A.D. 1806.=--Maréchaux (Peter Ludwig), correspondent of the French Galvani Society at Wesel, is the first to construct an effective dry pile containing paper discs. He makes known through M. Riffault (_Annales de Chimie_, Vol. LVII for January 1806, p. 61), that water is not essential to the production of galvanic effects, and his experiments are repeated for the Chemical Society by M. Veau Delaunay, as shown in _Journal de Physique_, Messidor, An. XIV.

This “Maréchausian Pile,” or _colonne pendule_, as it was originally denominated, consists of pairs of oven-dried cardboard, pasteboard, or blotting-paper, and of copper discs all pierced in such manner as to be suspended by three silken cords which hold them fast in position. Sturgeon remarks (“Researches,” pp. 199 and 239) that in this dry column the electric pulsations are, in consequence of the very great number of interrupting papers, less frequent than in either the processes of Volta or in that of Seebeck, notwithstanding which the instrument produces slow pulsatory currents.

REFERENCES.--W. Sturgeon’s “Annals of Electricity,” Vol. I. p.
256, note; Vol. VIII. pp. 379, 484; _Phil. Mag._, Vol. XXIV.
p. 183; Poggendorff, Vol. II. p. 46; “Roy. Soc. Cat. of Sci.
Papers,” Vol. IV. p. 236; Gilbert’s _Annalen der Physik_, Vols.
X.-XXVII _passim_, also Vol. XV. p. 98 and Vol. XVI. p. 115
giving a description of the Maréchaux electro-micrometer (screw
and silver leaf), likewise Vol. XXII, containing an account of
the observations made by M. Paul Erman.

=A.D. 1807.=--Young (Thomas), M.D., a very celebrated English scientist, “eminent alike in almost every department of human learning,” who was the associate of Davy at the Royal Institution, and who became the successor of Volta as Foreign Associate of the French Academy of Sciences, publishes his very elaborate “Course of Lectures on Natural Philosophy and the Mechanical Arts,” upon which he was assiduously engaged for five years, and a new edition of which was issued (with additional references and notes) by the Rev. P. Kelland, M.A., F.R.S., during the year 1845.

The above-named work comprises the sixty lectures which Dr. Young delivered during his connection with the Royal Institution and includes also his optical and other memoirs, as well as a very extended classified catalogue of publications in every leading department of science. His biographer in the “English Encyclopædia” remarks that Young’s lectures embody a complete system of natural and mechanical philosophy, drawn from original sources, and are distinguished not only by extent of learning and accuracy of statement, but by the beauty and originality of the theoretical principles. One of these is the principle of interferences in the undulatory theory of light. “This discovery alone,” says Sir John Herschel, “would have sufficed to have placed its author in the highest rank of scientific immortality, were even his other almost innumerable claims to such a distinction disregarded.” The first reception, however, of Dr. Young’s investigations of light was very unfavourable. The novel theory of undulation especially was attacked in the _Edinburgh Review_, and Dr. Young wrote a pamphlet in reply, of which it is said but one copy was sold, but it is now generally received in place of the molecular or emanatory theory.

His review and treatment of the field of electrical and magnetic phenomena, as may be imagined from the foregoing, is very extensive, and as no justice could be done it by making therefrom such extracts as would suitably come within the scope of the present “Bibliographical History,” only an extract from the lecture treating of “Aqueous and Igneous Meteors” will here be given.

Speaking of the aurora borealis, he says “that it is doubtful if its light may not be of an electrical nature. The phenomenon is certainly connected with the general cause of magnetism. The primitive beams of light are supposed to be at an elevation of at least 50 or 100 miles above the earth, and everywhere in a direction parallel to that of the dipping needle; but perhaps, although the substance is magnetical, the illumination, which renders it visible, may still be derived from the passage of electricity, at too great a distance to be discovered by any other test.... It is certainly in some measure a magnetical phenomenon; and if iron were the only substance capable of exhibiting magnetic effects, it would follow that some ferruginous particles must exist in the upper regions of the atmosphere. The light usually attending this magnetical meteor may possibly be derived from electricity, which may be the immediate cause of a change in the distribution of the magnetic fluid contained in the ferruginous vapours that are imagined to float in the air.”

The assumption of ferruginous particles or vapours, remarks Prof. Robert Jameson, of the Edinburgh University, seems, however, purely gratuitous and imaginary; and as iron is not the only substance or matter capable of exhibiting magnetic effects, light itself being susceptible of polarization, the above hypothesis is, therefore, untenable even on the ground upon which it has been rested by its author. But it is, nevertheless, certain that the cause of this luminous meteor is intimately connected with magnetism and electricity; or, rather, as the magnetic is variously modified and effected by the electric power, with the phenomena of electro-magnetism.

REFERENCES.--Young’s Catalogue for “Aurora Borealis” and
“Terrestrial Magnetism” (“Lectures,” London, 1807, Vol. II. pp.
440–443, 488–490), “Journal Roy. Inst.,” Vol. I; Dr. George
Peacock’s “Life of Thomas Young”; also “Miscellaneous Works of
T. Young,” London, 1855; “Memoirs of the Life of Thos. Young,”
London, 1831; also Vol. XIII of John Leitch’s “Hieroglyphical
Essays and Correspondence,” all of which contain every
contribution made by the scientist to the _Phil. Trans._, as
well as many other important articles communicated by him to
other scientific publications of his time; “Eloge Historique
de Dr. Thomas Young,” par M. Arago, in _Mém. de l’Acad. Roy.
des Sc._, etc., Tome XIII. p. 57; _Quarterly Review_ for April
1814; Tyndall, “Heat as a Mode of Motion,” 1873, pp. 267,
268; _Annales de Chimie_, Feb. 1815; Whewell, “History of the
Inductive Sciences,” 1859, Vol. II. pp. 92, 96, 106, 111–118.

=A.D. 1808.=--Pasley (Charles William), F.R.S., D.C.L., K.C.B., who was at the time aide-de-camp to Sir John Moore, became Major-General in 1841 and Lieutenant-General in 1851, gives at pp. 205, 292, Vol. XXIX, and at p. 339, Vol. XXXV of Tilloch’s _Philosophical Magazine_, a description of the original and improved methods of constructing his “polygrammatic telegraph.”

The apparatus, as first devised by him between the years 1804 and 1807, consists of four posts, each bearing a pair of pivoted arms, which latter can be placed at different angles to indicate all desired numerals and letters. After he had seen the French semaphore during 1809 he improved his telegraph, employing but one post, upon which were three pairs of pivoted arms representing hundreds, tens and units.

In 1823 Pasley (then a Lieutenant-Colonel, Royal Engineers) issued a pamphlet entitled “Description of the Universal Telegraph for Day and Night Signals,” wherein he announces the abandonment of the polygrammatic principle. For day service he employs an upright post with two movable arms attached to the top on a pivot. Each arm is capable of assuming seven different positions, besides the quiescent position called the _stop_, in which the arms are turned down and concealed by the post. To prevent signals being seen in reverse, another arm, called an _indicator_, is added to one side of the post. For night signals he places a central lamp at the top of the post, as well as a lamp at the end of each arm, and suspends a fourth lamp, as an indicator, upon a light crane projecting horizontally beyond the range of both movable arms. Motion to the arms was communicated by means of an endless chain passing over two pulleys. Up to this time the semaphores employed by the Admiralty had been constructed without provision being made for the display of night signals.

Pasley was the first to apply the heating power of the galvanic battery to a useful practical purpose. While engaged on the River Thames he was written to by Mr. Palmer (Alfred Smee, “Electro-Metallurgy,” p. 297), who advised him to employ the galvanic battery instead of the long fuse then in common use, and as soon as he was made acquainted with the method of operating he at once adopted it and applied it effectively, during the year 1839, to the removal of the sunken hull of the “Royal George,” at Spithead.

REFERENCES.--Sturgeon’s “Scientific Researches,” Bury, 1850, p.
174; Knight’s “Mech. Dict.,” Vol. I. p. 784; also “Documents
relatifs à l’emploi de l’Electricité,” etc., Paris, 1841, taken
from the _United Service Journal_ and the “Militaire Spectateur
Hollandais.” Consult likewise, “Trans. of the Society ... Arts,”
Vol. XXXIX, London, 1821, for Peter Barlow, XL. pp. 76–100,
and for Lieut. Nicolas Harris Nicolas, XL. p. 104; also Vol.
XLII, London, 1824, for Mr. A. Westcott, pp. 165–166. A patented
telegraph by James Boaz is alluded to in Vol. XII. pp. 84–87 of
the _Phil. Magazine_.

Following close upon Pasley’s original telegraphic contrivance were several other methods of conveying intelligence at a distance, introduced at this period, worthy of mention here.

The Chevalier A. N. Edelcrantz, Swedish savant, sent to the London Society of Arts a model of his apparatus, which is to be found minutely described in Vol. XXVI. pp. 20, 184–189, of the _Transactions_ of that institution. A description of his earlier contrivances for the same purpose had already been published at Stockholm in the year 1796, and after being translated into French had been noticed in William Nicholson’s _Journal of Natural Philosophy_ for 1803. The one he finally adopted in 1808 consisted of ten boards placed in three vertical ranks, the central one having four boards and the side ranks three boards each. By this arrangement 1024 signals could be clearly shown, and it was possible, by observing the _order_ in which the boards were exhibited, to make as many as 4,037,912 changes. He subsequently advised attaching lamps to the boards for night service. His system of working the boards, though very complicated, could be controlled by only one person, while the English method required several men to hold the shutters during heavy weather. As it was, his method is said to have been in constant use for fully twelve years prior to 1808 on both sides of the Baltic, and to have likewise served to transmit signals between Sweden and England.

Mr. Henry Ward, who had observed the difficulty with which the telegraph was worked at Blandford, in Dorsetshire, contrived the apparatus described in Vol. XXVI. pp. 20, 207–209 of the London _Journal of the Society of Arts_. The grooved wheels which are fixed upon the axis of the shutters to receive the ropes by which they are turned have the grooved portion of the rim formed in two segments, which are so attached to the periphery of the wheels by steel springs that they fly off and remain a little distance off when there is no strain upon the ropes, although so soon as a rope is pulled its pressure forces the segments into close contact with the solid rim of the wheel. In the segments are two notches, which, when the shutters are in either of their required positions, engage with a fixed catch so soon as the strain on the ropes is relaxed, and thus hold the shutters steady without any aid from the attendant. The pulling of a rope by drawing the segments close to the wheel releases the catch, and consequently enables the attendant to return any shutter to its original position.

Lieutenant-Colonel John Macdonald, F.R.S., who was already favourably known by two Reports on the Diurnal Variation of the Magnetic Needle observed at Fort Marlborough, Sumatra, and at St. Helena (_Philosophical Transactions_ for 1796, p. 340, and for 1798, p. 397, also “Eighth Encycl. Brit.,” Vol. XIV. p. 54), publishes (1808–1817) two treatises upon his “Terrestrial Telegraph,” accompanied by an extensive “Telegraphic Dictionary.” His contrivance consists of thirteen boards or shutters arranged, like those of Edelcrantz, into three vertical ranks representing hundreds, tens and units. Twelve of the boards are capable of producing 4095 distinct combinations, and the thirteenth or auxiliary board, which is mounted over the centre of the apparatus, doubles that number. A flag or vane is added to the hundred side to distinguish it in whatever direction it may be viewed, and a ball sliding upon the staff which supports it affords the means of again doubling the number, so that, on the whole, 16,380 distinct signals can be obtained. He subsequently adopted a modification of the contrivance introduced by Pasley in 1809, and also described a sort of a “Symbolic Telegraph,” in which symbols like those of Dr. Hooke, but representing numerals instead of alphabetical characters, were dropped into open spaces denoting hundreds, tens and units. He further suggested a useful flag telegraph for the navy and devised several schemes for night telegraphs both for land and sea, one of which latter consists of three sets of four lights each, with an additional or _director_ light to each set, affording the same extensive powers as his large board or shutter telegraph (_Phil. Mag._, Vols. LVII. pp. 88–93, and LVIII. pp. 99–103).

Major Charles Le Hardy communicates in 1808 to the London Society of Arts, Vol. XXVI. pp. 20, 180–183, a novel contrivance consisting of a large framework with nine radiating bars, representing the numerals from 1 to 9, and four sets of other bars intersecting them so as to form four concentric polygons, which latter express units, tens, hundreds and thousands; thousands being shown by the innermost polygon. Attached to the centre of the apparatus are four slender arms, carrying four square boards, the lengths of these arms being such that the board of one may, during the revolution of the arm, traverse the polygon which represents thousands, that of another the polygon representing hundreds, etc. By the addition of two other boards at the upper corners, one of which denotes 10,000 and the other 20,000, or, when displayed together, 30,000, the total range of the telegraph is from 1 to 39,999 (_Philosophical Magazine_, Vol. XXXIII. p. 343).

In the twenty-seventh volume of the _Transactions_ of the London Society of Arts will be found the telegraphic devices of Knight Spencer and of Lieutenant James Spratt (pp. 20, 163–169), while the thirty-third volume contains (at pp. 23, 118–121) a description of the contrivance of Alexander Law, intended for service on both sea and land. These, it may be said, are the only additional telegraphic methods worthy of note introduced up to the time when the English Admiralty adopted the system proposed by Sir Home Popham in 1816. The “anthropo-telegraph” of Knight Spencer, though laid before the Society of Arts in 1808, had been used as early as 1805. It consisted merely of two circular discs of wicker work, painted white with a black circle in the centre, to be held in different positions with respect to each other. The device of Lieutenant Spratt was more simple still, for it consisted only in holding a kerchief in various positions; yet, simple as it was, it served as a means of communication between vessels before the battle of Trafalgar, and it was also successfully used to converse between Spithead and the ramparts at Portsmouth, etc.

REFERENCES.--For Mr. Knight Spencer’s other papers, see the
_Philosophical Magazine_, Vols. XXXVI. p. 321, and XL. p. 206,
and, for different methods of telegraphing, see Mr. Macdonald’s
“Treatise,” published in 1817, as well as, more particularly,
Vols. XXVI, XXXIV, XXXV, XXXVI of the _Transactions of the
Society of Arts_; likewise Rohde’s “Système complet de Signaux
...” published 1835.

=A.D. 1808.=--Callender--Calendar (Elisha), of Boston, Mass., obtains, on Oct. 3, 1808, for his lightning rod, an American patent, which latter is the first one in the line of electricity issued by the United States.

REFERENCES.--H. L. Ellsworth’s “Digest of Patents,” Washington,
1840, p. 234; Edmund Burke, “A List of Patents,” Washington,
1847, p. 185; “List of United States Patents,” Washington, 1872,
p. 67.

=A.D. 1808.=--Bucholz (Christoph--Christian--Friedrich), distinguished German chemist, receives his diploma as a physician at Rinteln, prior to graduating at the Erfurt University, and publishes “Ueber die Chimischen ... metallen,” giving a description of the chain bearing his name. The latter was the result of experiments made by him to prove that the electricity in the pile results from the oxidation of one of the metals and also to establish a comparison between the quantity of electricity obtained and the amount of oxygen absorbed by the one metal.

REFERENCES.--“Biographie Universelle,” Bruxelles, 1843–1847,
Vol. III. p. 227; A. F. Gehlen, _Jour. für Chem. und Phys._,
Vol. V; L. Figuier, “Exp. et Hist.,” Paris, 1857, Vol. IV. p.
426; “La Grande Encyclopédie,” Vol. VIII. p. 315, and also the
letter of J. B. Van Mons to Bucholz, Brussels, 1810.

=A.D. 1808.=--Amoretti (Carlo), Italian naturalist, who was allowed (1772) to withdraw from the order of St. Augustine that he might devote himself exclusively to scientific researches, gives, in his “Della rabdomanzia ossia elettrometria,” a complete history of the divining rod, and treats also therein of animal magnetism, etc. His investigations of the electric polarity of precious stones show, among other results, that the diamond, the garnet and the amethyst are - E, while the sapphire is + E.

REFERENCES.--For a further account of the _Virgula Divina_, or
divining rod (_baguette divinatoire_), see the “Gentleman’s
Magazine” for 1751, Vol. XXI; also the notes at foot of pp.
91–106 of Baron Karl Von Reichenbach’s “Physico-Physiologicæ
Researches,” translated by Dr. John Ashburner, London, 1851.
In the latter, reference is made to Pierre Le Lorrain de
Vallemont’s “La Physique Occulte,” etc. (1693), to a work
written by Count J. de Tristan, to the “Mémoire,” etc., of
Tardy de Montravel (1781) and to Pierre Thouvenel’s “Mémoires,”
etc., the last named bearing the Paris-London imprint of
1781–1784, and attempting to show relations existing between
the rod and electricity and magnetism. Allusion is likewise
made in the afore-named work to the translation by Dr. Hutton
(1803) of Jean Etienne Montucla’s (1778) improvement of Jacques
Ozanam’s “Récréations Mathématiques et Physiques,” originally
built upon Leurechon’s “Récréations Mathématiques,” and first
published in Paris during the year 1724. For Reichenbach, see
“Le Cosmos,” Nos. 703–705 for July 16, 23 and 30, 1898; “Cat.
Sc. Pap. Roy. Soc.,” Vol. I. pp. 139–140; Vol. VIII. pp. 720,
721. Besides the above, reference should be had to the lecture
of Prof. Rossiter W. Raymond before the Philadelphia Electrical
Exhibition of 1884, and to the article in Paris _Cosmos_ of Jan.
3, 1891, which alludes to the works of P. Lebrun (1702), Albert
Fortis (1802), Dr. Charpignon (1848), Abbé Chevalier (1853),
and M. E. Chevreul “De la baguette ...” (1854). Consult also,
Eusebe Salverte, “The Philosophy of Magic.,” Vol. II. chap. xi.
speaking of Pryce’s “Mineralogia Cornubiensis” (1778); Theod.
Kirchmaier, “De Virgula divinatrice,” 1678; F. Soave, (_Opus.
Scelti_, III. p. 253), 1780; F. M. Stella (_Opus. Scelti_, XIII.
p. 427), 1790; G. B. San Martino (_Opus. Scelti_, XVII. p. 243),
1794; L. Sementini, “Pensieri e Sperimenti ...” 1811; A. M.
Vassalli-Eandi (_Opus. Scelti_, XIX. pp. 215, etc.); Kiesser,
_Archiv._, Vol. IV. p. 62; at Vol. I. p. 265, of Blavatsky’s
“Isis Unveiled”; “Biographie Générale,” Vol. II. pp. 290, 291;
“Roy. Soc. Catal. of Sc. Papers,” Vol. I. p. 58.

=A.D. 1808.=--Lebouvier-Desmortiers (Urbain René Thomas), French writer, who had called attention to the danger attending the bodily application of the galvanic fluid, through the _Journal de Physique_ of 1801 (p. 467), transmits another Mémoire to the same publication upon an improved electrical (_briquet_) tinder box.

The cylinder, which had previously been made of copper, he constructed of glass as illustrated by Delaunay at Plate IX. fig. 105, of his “Manuel,” etc., Paris, 1809. With the new contrivance he was enabled to exert considerable force upon the piston, and it was generally necessary to push the latter suddenly in order to so compress the air as to light the (_amadou_) spunk attached to the lower portion of the cylinder.

REFERENCES.--See his “Examen des principaux systèmes ...”
Paris, 1813; J. C. Poggendorff, _Biogr. Liter. Hand._ ...
Vol. I. p. 1399; Larousse, _Dict. Univ._, Vol. X. p. 290;
_Journal de Médecine_, Vol. XXVI. pp. 298–303; _Catal. Sc. Pap.
Roy. Soc._, Vol. III. p. 910; C. H. Wilkinson, “Elements of
Galvanism,” London, 1804, Vol. I. p. 461; V. Delaunay, “Manuel
de l’Electricité,” Paris, 1809, pp. 151–153; Detienne, “De
l’électricité de pression” (_Journal de Physique_, 1777, Vol.
IX).

=A.D. 1809.=--Krafft (Wolfgang Ludwig), Professor of Experimental Philosophy in the Imperial Academy of Sciences of St. Petersburg is the author of “Uber ein hypothet ...” wherein is given the result of his investigations of the phenomena of terrestrial magnetism.

Comparing Biot’s examination of the dip observations previously made by Humboldt, Krafft simplified the former’s conclusions, showing that if we measure the latitude from the magnetic equator, the tangent of the dip is double the tangent of such latitude, or, as he expresses it: “If we suppose a circle circumscribed about the earth, having the two extremities of the magnetic axis for its poles, and if we consider this circle as a magnetic equator, the tangent of the dip of the needle, in any magnetic latitude, will be equal to double the tangent of this latitude.”

Krafft gave a complete theory of the _electrophorus_ in the first part of the 1778 “Acta Acad. Petrop.,” which latter also contains his experiments with Canton’s phosphorus and his observations on the aurora of February 6–17 of the same year. The results of many of his other investigations are to be found in Part XI of the work mentioned as well as in Vols. XV, XVII and XIX of the “Novi Commentarii Academiæ Petropolitanæ.”

=A.D. 1809.=--Pinkerton (John), gives in his “Voyages and Travels,” published at London (Vol. IV. pp. 1–76) a reprint of the rare volume entitled “Account of Paris at the close of the Seventeenth Century,” by Martin Lister, M.D., wherein are detailed several surprisingly interesting experiments made by Mr. Butterfield with his wonderful collection of loadstones. It is therein stated that one of these loadstones, when unshod, weighed less than a dram and would suspend a dram and a half, but when shod would attract 144 drams of iron, whilst another of the loadstones, weighing 65 grains, attracted 14 ounces, or 140 times its own weight; another would work through a wall eighteen inches in thickness, etc. etc.

=A.D. 1809.=--Children (John George), an English scientist to whom reference has already been made, more particularly under Cruikshanks, A.D. 1800, communicates to the _Philosophical Transactions_, “An account of some experiments performed with a view to ascertain the most advantageous method of constructing a voltaic apparatus for the purposes of chemical research.” This paper appears also in Vol. XXXIV of the _Philosophical Magazine_.

Four years later (1813) he publishes a description of his magnificent galvanic battery, the largest ever constructed on the plan suggested by Dr. Wollaston. This consisted of twenty pairs of copper and zinc plates, each six feet long and two feet eight inches wide, the united capacities of the cells being 945 gallons. With this battery he confirmed Davy’s observation that “intensity increases with the number (of plates) and the quantity of the electricity with the extent of surface.” It is reported that, when in full action, the battery rendered a platinum wire five feet six inches long and ¹¹⁄₁₀₀ of an inch in diameter red-hot throughout so as to be visible in full daylight; that eight feet six inches of platinum wire ⁴⁴⁄₁₀₀ of an inch in diameter were easily heated red; that a bar of platinum one-sixth of an inch square and two and a quarter inches long was heated red-hot and fused at the end; and that a round bar of the same metal, ²⁷⁶⁄₁₀₀₀ of an inch in diameter and two and a half inches long, was heated bright red throughout.

The result of many other investigations which he also made in 1813 and during 1815 showed that metallic wires (eight inches long and ¹⁄₃₀ of an inch diameter) became red-hot in the following order: platinum, iron, copper, gold, zinc, silver; and he deduced that their conducting power was in the inverse order, silver conducting best and platinum least. Tin and lead fused immediately at the point of contact, and the oxides of tungsten, uranium, cerium, titanium, iridium and molybdenum were also fused. An opening made with a saw across an iron wire having been filled with diamond powder, the diamond was liquefied and the contiguous iron became steel. (See the Pepys entry at A.D. 1802.)

REFERENCES.--For Children’s other experiments, consult “_Phil.
Mag._,” Vol. XLII. p. 144; Vol. XLVI. pp. 409–415; _Phil.
Trans._ for 1815, pp. 368–370, also Dr. Wm. Henry’s “Elem. of
Exper. Chem.,” London, 1823, Vol. I. pp. 168–174; Dr. Thomas
Thomson, “Outline of the Sciences,” London, 1830, pp. 524–526;
Louis Figuier, “Expos. et Hist. ...” Paris, 1857, Vol. IV. pp.
389–390; Becquerel, Vol. I. p. 52; “Encycl. Metrop.,” Vol.
IV. pp. 179, 222; Gmelin’s “Chemistry,” Vol. I. p. 424; “Cat.
Sc. Papers Roy. Soc.,” Vol. I. p. 317; Vol. II. p. 26; “Bibl.
Britan.,” Vol. XLIII, 1810, p. 67 and Vol. I of the N.S. for
1816, p. 109.

=A.D. 1809–1810.=--Oken (Lorenz)--originally Lorenz Ockenfuss--celebrated German naturalist, while occupying the post of Extraordinary Professor of Medicine at the University of Jena, publishes the great work “Lehrbuch der Naturphilosophie,” which was translated into English by Dr. A. Tulk and published in London, during 1847, by the Royal Society, under the title of “Elements of Physico-Philosophy.”

This work, says his biographer in the “English Cyclopædia” (Vol. IV. p. 557), takes the widest possible view of natural science: it is interesting as a document in the history of a great mental movement and contains the germs of those principles which are now regarded as the secure generalization of well-observed facts.

From the epitome of the work given in the “Encyclopædia Britannica,” the following is extracted: “Polarity is the first force which appears in the world.... Galvanism is the principle of life ... the vital force ... the galvanic process is one with the vital process.... There is no other vital force than the galvanic polarity.”

According to Dr. Richard Owen, Lorenz Oken contends that organism is galvanism residing in a thoroughly homogeneous mass. A galvanic pile, pounded into atoms, must become alive. In this manner, nature brings forth organic bodies. The basis of electricity is the air; of magnetism, metal; of chemism (the name he gives to the influence that produces chemical combination), salts. The basis of galvanism, in like manner, is the organic mass. Accordingly, whatever is organic is galvanic; whatever is alive is galvanic. Life, organism, galvanism, are one. Life is the vital process; the vital process is an organic or galvanic process. Galvanism is the basis of all the processes of the organic world.... God did not make man out of nothing, but took an elemental body then existing, an earth-clod or carbon, moulded it into form, thus making use of water, and breathed into it life, viz. air, whereby galvanism or the vital process arose.... Organization is produced by the co-operating process of light and heat. The ether imparts the substance, the heat the form, the light the life.... The life of an inorganic body is a threefold action of the three terrestrial elements, in which three processes galvanism consists. The nutrient process is magnetic, present and entire in every part of the body, and wheresoever it is withdrawn there is death.... These three processes constitute the galvanic process. Thus the galvanic circle is complete, and motion is the manipulation of galvanism. The process of motion is synonymous with the galvanic process--this is the vital process.

REFERENCES.--The extended biography of Lorenz Oken, embracing
a list of his chief works and original essays at pp. 498–503,
Vol. XVI of the Eighth “Encycl. Britan.”; Dr. William Whewell’s
“History of the Inductive Sciences,” 1859, Vol. II. p. 477;
“Hist. des Sciences,” par F. L. M. Maupied, Paris, 1847, Vol.
II. pp. 466–514.

=A.D. 1809.=--Luc (Jean André de), celebrated natural philosopher of Swiss extraction (though from 1773 until his death in 1817, a resident of England, where he became reader to Queen Charlotte, the consort of George III), transmits to the Royal Society a long paper treating of the separation of the chemical from the electrical effects of the pile, with a description of the electric column and aerial electroscope.

In this communication, says Dr. Young, he advanced opinions so little in unison with the latest discoveries of the day, especially with those of the President of the Royal Society, that the Council probably thought it would be either encouraging error or leading to controversy to admit them into the _Philosophical Transactions_. He had, indeed, on other occasions shown somewhat too much scepticism in the rejection of new facts; and he had never been convinced even of Mr. Cavendish’s all-important discovery of the composition of water.

The paper was afterwards published in _Nicholson’s Journal_ (Vol. XXVI), and the dry column described in it was constructed by various experimental philosophers. It exhibited a continual vibrating motion, made sensible by the sound of a little bell, which was struck by the pendulum at each alternation; and during many months the vibration was more or less rapid, according to circumstances affecting the column.

This dry column consists of discs of Dutch gilt paper, alternated with similar discs of laminated zinc, so arranged that the order of succession will be maintained throughout. When sufficiently dry these are piled upon each other, the gilt side of the paper being in contact with the zinc, and all are pressed together in a glass tube by a brass cap and screw connected at each end with a metallic wire. The column presented by De Luc to the Royal Society consisted of 300 discs of zinc and of 300 discs of gilt paper. It is said that, with a larger column, the vibration of a brass ball suspended between two bells was so continued as to maintain a perpetual ringing for over two years; that with an apparatus comprising 20,000 groups of silver, zinc and double discs of writing paper, sparks have been obtained, while a Leyden jar was charged in ten minutes with sufficient electricity to produce shocks and to fuse an inch of platinum wire of an inch in diameter; and that a similar pile, in the Clarendon Laboratory at Oxford, rang ten small bells continuously for over forty years.

In Vols. XXXV, XXXVI and XXXVII of the “Phil. Mag.,” and in Vols. XXVII and XXVIII of “Nicholson’s Journal,” André de Luc shows how the dry column can be used for determining the insulating qualities and conducting power of bodies, it having been also employed as are aerial electroscopes to indicate the electrical changes taking place in the atmosphere. The other volumes of the same publications named below contain additional papers upon electricity, galvanism, etc., while at p. 392, Vol. L of the _Phil. Mag._ will be found an account of De Luc’s life and principal works, the latter being likewise mentioned in Vol. XXV of the “Biographie Universelle.”

REFERENCES.--B. M. Forster, “Description ... elec. col. ...
De Luc ...” London, 1810; _Phil. Mag._, Vol. XXXVII. p. 197;
J. D. Maycock, _Phil. Mag._, Vol. XLVIII. pp. 165, 255; L.
Configliachi, “Osservazioni sulle pile a secco”; M. Delezenne,
“Expériences sur les piles sèches”; _Bibl. Brit. Sci. et Arts_,
Vol. XLVII, 1811, pp. 3, 113, 213, 313; Vol. XLIX, 1812,
pp. 88–92 (Necrology of J. A. De Luc), Vol. L, 1812, p. 351
(“Nicholson’s Journal,” No. 126), also the “Bibl. Britan.” for
1812, Vol. L. pp. 279–290 (Nicholson’s _Journal_, April 1812),
for J. D. Maycock’s reply to De Luc’s objections concerning
voltaic plates (“Phil. Mag.,” Vol. XLVIII. pp. 165, 255);
Gmelin’s “Chemistry,” Vol. I. pp. 424–427; G. J. Singer’s
“Elements of Electricity” and William Sturgeon’s _Annals of
Electricity_, _passim_, as well as his “Researches,” Bury, 1850,
pp. 147, 199, 261; De la Rive’s “Treatise on Electricity,” Vol.
II. p. 852; _Annales de Chimie et de Physique_, Vol. II. pp.
79–82 for May 1816; Gilbert’s _Annalen_, Vol. XLIX; also Vols.
VII, 1801, to Vol. LXXIV, 1821, for various articles upon the
dry pile, etc.; G. Schübler, “Uber De Luc’s Elektr. saüle ...”
1813; Geo. Wilson’s “Life of Cavendish,” London, 1851, p. 66,
etc.; “Nicholson’s Journal,” Vols. XXI, XXII, XXXII, XXXIII,
XXXV; _Phil. Mag._, Vols. XLII, XLV, the last named containing,
at pp. 359–363, Mr. G. J. Singer’s paper on “The Electric Column
considered as ... first mover for Mechanical Purposes,” while
at pp. 466, 467 is the communication of Mr. Francis Ronalds on
De Luc’s electric column. The latter is also specially referred
to in Vols. XLIII. pp. 241, 363; XLVI. p. 11; XLVII. pp. 47,
48; XLVIII. pp. 165, 255; LVII. pp. 446, 447; while at p. 55 of
Vol. XLIX is a paper relative to a “combination of the electric
column, the thermometer, barometer and hygrometer in one
instrument, for electro-atmospherical researches.”

=A.D. 1809.=--Sömmering (Samuel Thomas von), German anatomist and physiologist, first employs voltaic, or contact, electricity for the transmission of telegraphic signals.

Both his original and perfected working instruments were constructed between July 9 and August 6, 1809 (_Journal Franklin Institute_, 1859, Vols. XXXVII and XXXVIII; _Journal Society of Arts_, Vol. VII. p. 235). The complete apparatus consists of thirty-five gold rods placed into glass tubes starting from a reservoir of acidulated water and connecting with thirty-five silk-covered wires, which are run into thirty-five apertures of copper (corresponding with twenty-five letters and ten figures) upon a wooden stand into each opening of which the wires of the voltaic pile can be inserted. When the latter are connected, the bubbles rising through the decomposition of the water are made to enter the lettered glass receivers through which the messages can be deciphered. On August 8, 1809, he was able to transmit intelligence a distance of 1000 feet, and twenty days later he presented his apparatus to the Bavarian Academy of Sciences (Fahie, “Hist. of Electric Telegraphy,” p. 228).

Sömmering’s telegraph was carried by Dominique Jean Larrey, chief surgeon of the French armies, to Paris, where it was delivered by him to the French Academy of Sciences, Dec. 5, 1809, and Dr. Hamel states that Biot, Carnot, Charles and Monge were appointed by that body to report upon the new invention (_Journal of the Franklin Institute_ for 1859, Vol. XXXVIII. p. 398). In 1810 and 1811, Sömmering reduced the number of wires in his apparatus to twenty-seven. These brass or copper wires were first insulated with a covering of gum lac and then with silk thread, after which they were united into a thread-covered cable 1000 feet in length. The cable was in turn covered with heated gum lac or with a ribbon plunged in a solution of the same substance. The Russian Count Jeroslas Potocki took the new instrument to Vienna and submitted it, July 1, 1811, to the Emperor Francis I, while another model of the apparatus was sent to William Sömmering, then at Geneva, where it was shown to De la Rive, Auguste Pictet and other scientists. During March 1812 this instrument carried intelligence 10,000 feet, or ten times the distance previously reached.

REFERENCES.--Dr. Hamel, Cooke’s reprint, pp. 7, 8. See
Sömmering’s own description of this, the first electro-chemical
telegraph, in “Der Elektrische,” etc., published by his son
William at Frankfort, 1863, or the translations at p. 751 of
Noad’s “Manual,” London, 1859, and at pp. 230–234 of Fahie’s
“Hist, of Elec. Tel.,” London, 1884; Dr. Hamel, in _Jour. Soc.
of Arts_, for 1859, p. 453, or the reprint of W. F. Cooke in
1859, Vol. VII. pp. 595–599 and 605–610; Du Moncel, “Exposé,”
etc., Vol. III; _Comptes Rendus_, Tome VII for 1838, p. 81;
“De Bow’s Review,” Vol. XXV. p. 551; Highton’s “Elec. Tel.,”
p. 39; Harris, “Galvanism,” p. 35; Sturgeon’s _Ann. of Elec._,
Vol. III, March 1839, pp. 447–448; “Turnbull, Electric Magn.
Tel.” “Denkschr. Münch. Akad. ...” for 1809 and 1810, alluding
to his first experimental instrument made in 1807; Schweigger,
_Journal_, II. pp. 217, 240 of Vol. XX for 1817; Poggendorff’s
_Annalen_, Vol. CVII. pp. 644–647; “Smithsonian Report” for
1878, pp. 269–271; _Journal of the Franklin Institute_ for 1851,
Vol. XXI. pp. 330–332; Prime’s “Life of Prof. Morse,” 1875, pp.
263–275; “Bibl. Britan.,” Vol. XLIX, 1812, p. 19; “Traité de
tél. sous-marine,” E. Wünschendorff, Paris, 1888.

=A.D. 1810.=--Prechtl (Johann Joseph), German mathematician and chemist, director of the School of Arts and Navigation in Trieste, also professor in the Vienna Polytechnic Institute, is the author of several very interesting articles on electricity, magnetism, etc., which appeared in Gilbert’s _Ann. der Physik_ from Vol. XXXV for 1810, to Vol. LXVIII for 1821, as well as in Gehlen’s _Jour. für Chemie, Physik und Mineralogie_, Vols. V-VII. According to Figuier (“Expos, et Hist. ...” 1857, Vol. IV. p. 433) we owe to Prof. Prechtl a still more lucid explanation of the theory of electric distribution and equilibrium in the voltaic pile than was conveyed even by the learned Prof. Jäger (A.D. 1802).

Of the many separate treatises which he wrote up to 1836, and which are contained in the numerous publications cited below, the most important, by far, is doubtless that treating of the fundamental state of the magnetic phenomena of the electrical connecting wire and on the transverse electrical charge (“Uber d. transversal-magnetismus ...”) which is to be found in Schweigger’s _Journal für die Chemie und Physik_, Vol. XXXVI. pp. 399–410, and in Dr. Thomas Thomson’s _Annals of Philosophy_, N.S., Article I. vol. iv. pp. 1–6 for July 1822. Alluding to the last named, Mr. Sturgeon says (“Scientific Researches,” Bury, 1850, p. 29) that an _attempt_ is made by M. Prechtl to explain the manner in which the connecting wire acts upon the needle, but that his diagrams and his mode of reasoning are too complex to be entered into the “Researches.”

REFERENCES.--Poggendorff’s “Biograph.-Liter. ...” Vol. II. pp.
519, 520; Larousse, “Dict. Univ.,” Vol. XIII. p. 45; “Catal.
Sc. Papers Roy. Soc.,” Vol. V. pp. 3–5; Gehlen’s _Journal_,
Vols. VII. pp. 141–282; VIII. pp. 297–318; Gilbert’s _Annalen_,
Vols. XXXV, 1810, pp. 28–104; XLIV, 1813, pp. 108–111; LXVII,
1821, pp. 81–108, 221, 222, 259–276; LXVIII, 1821, pp. 104–106,
187–206; LXXVI, 1824, pp. 217–228; Brugnatelli’s “Giornale,”
Vol. III, 1810, pp. 477–486; Kastner, “Archiv. Natur.,” II,
1824, pp. 151–167; Wien, “Jahrb. Pol. Inst.,” Vol. XIV, 1829,
pp. 144–160, and Poggendorff’s _Annalen der Physik und Chemie_,
Vol. XV, 1829, pp. 223–238.

=A.D. 1810.=--The compiler of this “Bibliographical History” will doubtless be pardoned for introducing here an additional mode of “communicating intelligence” promptly at great distances. Reference is made to the first germ of pneumatic telegraphy sown by the English engineer, George Medhurst, during the year 1810.

The London _Telegraphic Journal_, which gives an extract from the specification of Medhurst’s patent “for a new method of conveying letters and goods with great certainty and rapidity by air,” states that the process took practical form only in 1854, when Latimer Clark laid down a one-and-a-half-inch lead pipe between the Electric Telegraph Company’s central station, Lothbury, and the London Stock Exchange. The system was extended in 1858 to Mincing Lane, and, two years later, Varley introduced the use of compressed air, so that messages were drawn one way by a vacuum, and propelled in the opposite direction by a prenum, instead of employing a vacuum both ways, as Latimer Clark had previously done. During the year 1865 the system, then considerably modified, was introduced into Paris, and it was also made use of, at about the same time, by the Messrs. Siemens, who employed it between the Bourse and the telegraph station in the city of Berlin.

=A.D. 1810.=--Jacopi (Joseph), Italian physician, anatomist and physiologist (1774–1813), pupil of the famous Scarpa, makes known through his “Elementi di Fisiologia e Notomia comparata” (“Eléments de Physiologie et d’Anatomie comparée”), the results of his very extended investigations of the electrical organs of the _torpedo_.

To him is due the first clear description of the electrical lobes situated in the _torpedo’s_ brain and of its relation to the eighth pair of nerves distributed throughout the hexagonal columns, which latter received also from him a very extended notice in the above-named work. The fifth ramification of nerves was first observed by Carus, and the most valuable investigation relative to the fourth and last important group of nerves directly connected with the electrical organs was made by the celebrated Italian professor, Carlo Matteucci.

REFERENCES.--Larousse, “Dict. Univ.,” Vol. IX. p. 867; C.
Matteucci, “Traité des Phénomènes Electro-Phys.,” Paris, 1844,
pp. 283–318; Geoffroy St. Hilaire at A.D. 1803.

Another author, Delle Chiaje, likewise gave a description of
the rhomboidal sinus-shaped protuberance which he calls _lobo
pagliarino_ (straw-coloured lobe), and which he considers as
formed of one mass but does not admit its important connection
with the electrical organs.

=A.D. 1811.=--Poisson (Siméon Denis), a very able French scientist, communicates to the “Institut des Mathématiques et Physiques” and publishes at Paris under the caption “Traité de Mécanique,” his analytical observations of the electric phenomena which, it has been truly said, actually establish a new branch of, and is the best elementary work extant upon, mathematical physics. One of his biographers remarks that Poisson’s object was “to leave no branch of physics unexplored by aid of the new and powerful methods of investigation which a school, yet more modern than that of Lagrange and Laplace, had added to the pure mathematics.”

As shown, notably by Sir David Brewster in his able article on “Electricity” in the eighth “Encycl. Brit.” (Vol. VIII. p. 531), and by Noad, in his “Manual” (London, 1859, pp. 15, 16):

“Poisson adopted as the basis of his investigations the theory of two fluids, proposed by Symmer and Dufay, with such modifications and additions as were suggested by the researches of Coulomb. He deduced theorems for determining the distribution of the electric fluid on the surfaces of two conducting spheres, when they are placed in contact or at any given distance, the truth of which had been established experimentally by Coulomb before the theorems themselves had been investigated. On bodies of elongated forms, or those which have edges, corners or points, it is shown as a consequence of the theory of two fluids that the electric fluid accumulates in greater depths about the edges, corners or points than in other places. Its expansive force, being therefore greater at such parts than elsewhere, exceeds the atmospheric pressure and escapes, while at other points of the surface it is retained.”

In the latter connection Mary Somerville remarks:

“There can hardly be a doubt but that all the phenomena of magnetism, like those of electricity, may be explained on the hypothesis of one ethereal fluid, which is condensed or redundant in the positive pole, and deficient in the negative; a theory that accords best with the simplicity and general nature of the laws of creation; nevertheless, Poisson has adopted the hypothesis of two extremely rare fluids, pervading all the particles of iron, and incapable of leaving them. Whether the particles of these fluids are coincident with the molecules of the iron, or that they only fill the interstices between them, is unknown and immaterial. But it is certain that the sum of all the magnetic molecules, added to the sum of all the spaces between them, whether occupied by matter or not, must be equal to the whole volume of the magnetic body.... M. Poisson has proved that the result of the action of all the magnetic elements of a magnetized body is a force equivalent to the action of a very thin stratum covering the whole surface of a body, and consisting of the two fluids--the austral and the boreal, occupying different parts of it; in other words, the attractions and repulsions externally exerted by a magnet are exactly the same as if they proceeded from a very thin stratum of each fluid occupying the surface only, both fluids being in equal quantities, and so distributed that their total action upon all the points in the interior of the body is equal to nothing. Since the resulting force is the difference of the two polarities, its intensity must be greatly inferior to that of either” (J. C. Wilcke at A.D. 1757, “Conn. of the Phys. Sci.,” 1846, s. 30 pp. 308, 309).

The “Mémoires de l’Institut” for 1811 contain Poisson’s very able papers showing the manner in which electricity is distributed on the surfaces of bodies of various figures and the thickness of the stratum of electricity existing throughout these bodies. Mrs. Somerville further observes of work already cited (s. 28):

“Although the distribution of the electric fluid has employed the eminent analytical talents of M. Poisson and M. Ivory, and though many of their computed phenomena have been confirmed by observation, yet recent experiments show that the subject is still involved in much difficulty. Electricity is entirely confined to the surface of bodies; or, if it does penetrate their substance, the depth is inappreciable; so that the quantity bodies are capable of receiving does not follow the proportion of their bulk, but depends principally upon the form and extent of surface over which it is spread; thus the exterior may be positively or negatively electric, while the interior is in a state of perfect neutrality.” (Consult J. Farrar, “Elem. of Elect. Magn. and Electro-Magn.,” 1826, pp. 50–56.)

In his treatment of the theories of magnetism, Brewster alludes again to the masterly investigations of Poisson, who, says he, appears to have been “the first to conceive the idea of absolute magnetic measurement.” In a short but luminous article at the end of the “Connaissance des Temps” for 1828, he describes the method for obtaining the value of H[ symbol] in absolute measure. His first and second “Mémoire sur la Théorie du Magnétisme” appeared during 1824–1825, at pp. 247, 488, Vol. V of the Transactions of the Paris Royal Academy, and were closely followed (Vol. VI. p. 441) by his Memoir on the theory of Magnetism in motion. _Translations_ of these will be found at pp. 336–358, 373, Vol. I and pp. 328–330, Vol. V of the _Edin. Jour. of Sci._ and at pp. 334, 335 of John Farrar’s “Elem. of Elect. Magn. and Electro-Mag.,” all published during the year 1826.

Poisson’s theoretical prediction of magne-crystallic action is thus alluded to by Dr. John Tyndall in his “Researches on Diamagnetism,” etc., London, 1870, pp. 13 and 66, 67:

“In March 1851, Professor William Thomson (Lord Kelvin) drew attention to an exceedingly remarkable instance of theoretic foresight on the part of Poisson, with reference to the possibility of magne-crystallic action.

“Poisson,” says Sir William, “in his mathematical theory of magnetic induction founded on the hypothesis of magnetic fluids (moving within the infinitely small magnetic elements), of which he assumes magnetizable matter to be constituted, does not overlook the possibility of those magnetic elements being non-spherical and symmetrically arranged in crystalline matter, and he remarks that a finite spherical portion of such a substance would, when in the neighbourhood of a magnet, act differently according to the different positions into which it might be turned with its centre tube fixed. But (such a circumstance not having yet been observed), he excludes the consideration of the structure which would lead to it from his researches, and confines himself in his theory of magnetic induction to the case of matter consisting either of spherical magnetic elements or of non-symmetrically disposed elements of any forms. Now, however, when a recent discovery of Plucker’s has established the very circumstance, the observation of which was wanting to induce Poisson to enter upon a full treatment of the subject, the importance of working out a magnetical theory of magnetic induction is obvious.

“Sir William Thomson then proceeds to make the necessary ‘extension of Poisson’s Mathematical Theory of Magnetic Induction,’ and he publishes a striking quotation from the ‘Mémoires de l’Institut,’ 1821–1822, Paris, 1826.”

REFERENCES.--Biography in “English Encycl.,” Vol. IV. p.
899; _Phil. Mag._ for 1851; Roy. Soc. Catal. of Sci. Papers,
Vol. IV. pp. 964–969; G. M. Racagni, “Sopra una Memoria ...”
1839; Johnson’s “Encycl.,” 1878, Vol. III. p. 227; eighth
“Britannica,” Vol. XV. p. 98; ninth “Britannica,” Vol. XV. pp.
241, 249; _Ann. de Chimie_ for Feb. 1824; “Le Globe,” No. 87;
Harris, “Magnetism,” p. 131; Whewell, “Hist. of the Inductive
Sciences,” 1859, Vol. II. pp. 43, 208, 209, 222, 223; Sir
William Thomson’s works, 1872; Thomas Thomson, “An Outline,”
etc., 1830, p. 351; _Mém. de l’Acad. des Sci._ for 1824–1826,
1838; _Soc. Philom._ for 1803, 1824–1826; Humboldt’s “Cosmos,”
London, 1849, Vol. I. pp. 104, 105, 130, 165–169; N. Bowditch,
“Of a mistake which exists in the calculation of M. Poisson
relative to the distribution of the electric matter upon the
surfaces of two globes, in Vol. XII of the “Mém. ... Sc. Math.
... de France”; _Mem. Amer. Acad._, O.S., Vol. IV. part i.
p. 307; Houzeau et Lancaster, “Bibl. Gén.,” Vol. II. p. 228.
Mention is made of Poisson’s principal writings, in Vol. XI. pp.
179–191 of M. Max Marie’s “Hist. des Sciences Mathém.,” Paris,
1888, but the complete list will be found in Vol. II of the
works of Arago.