Chapter XIX: Book I: chap. i. Therein, he says that Baptista Porta, who has made the (4)

Albertus Magnus constructed, after thirty years of experimentation, a curious machine which sent forth distinct vocal sounds, at which the very learned scholastic philosopher Saint Thomas Aquinas (“Angel of the Schools”) was so much terrified that he struck the contrivance with his stick and broke it. Bishop Wilkins alludes to this machine as well as to a brazen head devised by Friar Bacon, which could be made to utter certain words (“Journal des Savants” for 1899, and J. S. Brewer, “F. Rog. Bacon,” 1859, p. xci; also, “How Fryer Bacon made a Brasen Head to Speake,” at pp. 13–14 of the “Famous Historie of Fryer Bacon published at London for Francis Groue”).

Incidentally, it may be mentioned that Wolfgang von Kempelen, Aulic Counsellor to the Royal Chamber of the Domains of the Emperor of Germany, after witnessing some magnetic games shown to the Empress Maria Theresa at Vienna, constructed, during the year 1778, a speaking machine which “gave sounds as of a child three or four years of age, uttering distinct syllables and words” (Wm. Whewell, “Hist. of the Inductive Sciences,” Vol. II. chap. vi.; J. E. Montucla, “Hist. des Mathém,” Vol. III. p. 813).

_La Nature_, Paris, May 6, 1905, pp. 353–354, illustrates the _speaking head_ of l’Abbé Mical presented by him to the French Academy of Sciences July 2, 1783, and alludes to those of Albertus Magnus, Wolfgang von Kempelen, C. G. Kratzenstein, etc.

Two more curious productions, in pretty much the same line as Bergerac’s, can, with equal propriety, be inserted here.

The first is taken from the April number, 1632, of the _Courier Véritable_, a little monthly publication in which novel fancies were frequently aired: “Captain Vosterloch has returned from his voyage to the southern lands, which he started on two years and a half ago, by order of the States-General. He tells us, among other things, that in passing through a strait below Magellan’s, he landed in a country where Nature has furnished men with a kind of sponge which holds sounds and articulations as our sponges hold liquids. So, when they wish to dispatch a message to a distance, they speak to one of the sponges, and then send it to their friends. They, receiving the sponges, take them up gently and press out the words that have been spoken into them, and learn by this admirable means all that their correspondents desire them to know.”

The second is the production of one Thomas Ward, theological poet, who was born in 1640 and died in 1704. In the second canto of one of his poems occur these words:

“As Walchius could words imprison
In hollow canes so they, by reason,
Judgment and great dexterity,
Can bottle words as well as he;
And can from place to place convey them,
Till, when they please, the _reed_ shall say them;
Will suddenly the same discharge,
And hail-shot syllables at large
Will fly intelligibly out
Into the ears of all about:
So that the _auditors_ may gain
Their meaning from the breach of cane.”

REFERENCES.--Priestley, “History,” etc., 1775, p. 374, and
_Dantzig Memoirs_, Vol. I. p. 294.

=A.D. 1745.=--Grummert (Gottfried Heinrich), of Biala, Poland, first observes the return of the electric light _in vacuo_. In order to ascertain whether an exhausted tube would give light when it was electrified, as well as when it was excited, he presented one eight inches long and a third of an inch wide, to the electrified conductor, and was surprised to find the light dart very vividly along the entire length of the tube. He likewise observed that some time after the tube had been presented to the conductor, and exposed to nothing but the air, it gave light again without being brought to an electrified body (see _Dantzig Memoirs_, Vol. I. p. 417).

=A.D. 1745.=--Dr. Miles (Rev. Henry), of Tooting, D.D. (1698–1763) reads, March 7, before the English Royal Society a paper indicating the possibility of kindling phosphorus by applying to it an excited electric without the approach of a conducting body. This gentleman’s tube happening to be in excellent order upon this occasion, he observed, and doubtless was the first to notice, _pencils of luminous rays_, which he called _coruscations_, darting from the tube without the aid of any conductor approaching it.

In a paper which Dr. Miles read before the same Society on the 25th of January, 1746, he gave an account of other equally interesting experiments, one of which was the kindling of ordinary lamp spirits with a piece of black sealing wax excited by dry flannel or white and brown paper.

REFERENCES.--“Dict. Nat. Biog.,” Sidney Lee, Vol. XXXVII. p.
378; _Phil. Trans._, Vol. XLIII. pp. 290, 441; Vol. XLIV. pp.
27, 53, 78, 158, and the following abridgments: Hutton, Vol.
IX. pp. 107, 136, 191, 198, 207, 213, 232; John Martyn, Vol. X.
part ii. pp. 272, 277, 317, 319, 322–323, 325.

=A.D. 1745.=--This period was to witness a discovery which, according to Professor Tyndall, “_throws all former ones in the shade_,” and which Dr. Priestley calls “_the most surprising yet made in the whole business of electricity_.” This was the accumulation of the electric power in a glass phial, called the Leyden jar after the name of the place where the discovery was made. It was first announced in a letter to Von Kleist, dean of the cathedral of Kamin--Cammin--in Pomerania, dated the 4th of November, 1745, and addressed to Dr. Lieberkühn, who communicated it to the Berlin Academy. The following is an extract: “When a nail or a piece of thick brass wire is put into a small apothecary’s phial and electrified, remarkable effects follow; but the phial must be very dry or warm; I commonly rub it over beforehand with a finger, on which I put some pounded chalk. If a little mercury, or a few drops of spirit of wine, be put into it, the experiment succeeds the better. As soon as this phial and nail are removed from the electrifying glass, or the prime conductor to which it has been exposed is taken away, it throws out a pencil of flame so long that, with this burning machine in my hand, I have taken above sixty steps in walking about my room; when it is electrified strongly I can take it into another room and there fire spirits of wine with it. If while it is electrifying I put my finger, or a piece of gold which I hold in my hand, to the nail, I receive a shock which stuns my arms and shoulders.”

It is said that Cunæus, rich burgess of Leyden, accidentally made the same discovery in January 1746. It appears that Pieter Van Musschenbroek, the celebrated professor, while experimenting with his colleagues, Cunæus and Allamand, observed that excited bodies soon lost their electricity in the open air, attributable to the vapours and effluvia carried in the atmosphere, and he conceived the idea that the electricity might be retained by surrounding the excited bodies with others that did not conduct electricity. For this purpose he chose water, the most readily procured non-electric, and placed some in a glass bottle. No important results were obtained until Cunæus, who was holding the bottle, attempted to withdraw the wire which connected with the conductor of a powerful electric machine. He at once received a severe shock in his arms and breast, as did also the others upon renewing the experiment. In giving an account of it to the great scientist, René de Réaumur, Musschenbroek remarked: “For the whole kingdom of France, I would not take a second shock.” Allamand states that when he himself took the shock “he lost the use of his breath for some minutes, and then felt so intense a pain along his right arm that he feared permanent injury from it.”

In his “Cours Elémentaire de Physique,” Musschenbroek describes one of the peculiar electrical machines then being constructed by the well-known London instrument maker, George Adams, and a cut of it can be seen at p. 353, Vol. I. of the translation made by Sigaud de la Fond at Paris during 1769. Another of Adams’ machines is described and illustrated at p. 126 of the French translation of Cavallo’s “Complete Treatise,” published at Paris in 1785.

The invention of the Leyden jar is claimed with equal pertinacity for Kleist, Musschenbroek and Cunæus. While it is necessarily conceded that Von Kleist first published his discovery, it cannot be denied that his explanation of it is so obscure as, for the time, to have been of no practical use to others. It is stated by Priestley: “Notwithstanding Mr. Kleist immediately communicated an account of this famous experiment (which indeed it is evident he has but imperfectly described) to Mr. Winckler, at Leipzig, Mr. Swiettiki, of Denmark, Mr. Kruger, of Halle, and to the professors of the Academy of Lignitz, as well as to Dr. Lieberkühn, of Berlin, above mentioned, they all returned him word that the experiment did not succeed with them. Mr. Gralath, of Dantzig, was the first with whom it answered; but this was not till after several fruitless trials, and after receiving further instructions from the inventor. The Abbé Nollet had information of this discovery, and, in consequence of it says, in a letter to Mr. Samuel Wolfe, of the Society of Dantzig, dated March 9, 1746, that the experiment at Leyden was upon principles similar to that made with a phial half full of water and a nail dipped in it; and that this discovery would have been called the Dantzig experiment if it had not happened to have got the name of that of Leyden.”

In the thirty-eighth volume of the _Philosophical Transactions_, No. 432, p. 297, is given an abstract of a letter (dated Utrecht, January 15, 1733, O. S.), from Petrus Van Musschenbroek, M.D., F.R.S., to Dr. J. T. Desaguliers, concerning experiments made on the Indian Magnetic Sand, chiefly gathered along the seashore in Persia. After detailing his many observations, Van Musschenbroek asks: “And, now, what can this _sand_ be? Is it an imperfect magnet, or Subtile Powder of it, which, when it is grown up into a greater lump, makes the vulgar Loadstones? So I conjectured at first; but when I found by experience that common Loadstones, exposed to the fire, according to some of the methods above-mention’d, did rather lose of their force than gain, I alter’d my opinion; and now confess that I have not yet penetrated into the knowledge of the nature of this matter.”

REFERENCES.--Dalibard, “Histoire Abrégée,” p. 33; _Dantzig
Memoirs_, Vol. I. pp. 407, 409, 411; Johann Gottlob Kruger,
“Dissert. de Elect.,” Helmstadt, 1756 (Poggendorff, I. p. 1323);
Priestley, 1777, “The Hist. and Pres. State of Electricity,”
pp. 82–84; Opuscoli Scelti, 4to, xviii, 55; Pierre Massuet,
“Essais,” Leide, 1751; Musschenbroek’s “Epitome elementorum,”
etc., 1726, “Tentamina Experimentorum Naturalium,” 1731,
and his “Disertatio Physica experimentalis de Magnete,” as
well as his “Elementa Physicæ,” 1734, and the “Introductio
ad Philosophiam Naturalem,” 1762, the last-named two works
being greatly amplified editions of the “Epitome.” For
Musschenbroek--Musschenbrock--consult also _Phil. Trans._, Vol.
XXXII. p. 370; Vol. XXXVII. pp. 357, 408, also the following
abridgments: Baddam, 1745, Vol. VIII. p. 42; Reid and Gray, Vol.
VI. p. 161 (Musschenbroek to Desaguliers); Hutton, Vol. VII. pp.
105, 647 (magnetic sand); Eames and Martyn, Vol. VI. part ii. p.
255; John Martyn, Vol. VIII. p. 737 (magnetic sand). For this
magnetic sand, consult also Mr. Butterfield’s article in _Phil.
Trans._ for 1698, p. 336 and in the abridgments of Hutton, Vol.
IV. p. 310.

=A.D. 1745.=--Watson (William), M.D., F.R.S., an eminent English scientist, bears “the most distinguished name in this period of the history of electricity.” His first letters, treating of this science, are addressed to the Royal Society between March 28 and October 24, 1745, and, on the 6th of February and the 30th of October, 1746, he communicated other similar papers to the same Society, all which, like his subsequent treatises, are to be found in the _Philosophical Transactions_.

Dr. Watson, like most scientists at the time, made numerous experiments with the Leyden jar, and he was the first to observe the flash of light attending its discharge. He says: “When the phial is well electrified, and you apply your hand thereto, you see the fire flash from the outside of the glass wherever you touch it, and it crackles in your hand.” It is to him that we owe the double coating of the jar, as well as the _plus_ and _minus_ of electricity.

He also shows conclusively that glass globes and tubes do not possess in themselves the electrical power, but only serve “as the first movers or determiners of that power,” and he also proves that the electric fluid takes the shortest course, passing through the substance of the best medium of connection and not along its surface. This, he demonstrated by discharging a phial through a wire covered with a mixture of wax and resin.

In order to ascertain the velocity of the electric fluid from the Leyden phial and the distance at which it could be transmitted (John Wood, at A.D. 1726), Watson directed a series of experiments upon a very grand scale, with the assistance of Martin Folkes, President of the Royal Society, Lord Charles Cavendish, Dr. Bevis, Mr. Graham, Dr. Birch, Peter Daval and Messrs. Trembley, Ellicott, Robins and Short. On the 14th and 18th of July, 1747, they experimented upon a wire carrying the electricity from the Thames bank at Lambeth to the opposite bank at Westminster, across Westminster Bridge, and, on the 24th of July, at the New River, Stoke Newington, they sent a shock through 800 feet of water and 2000 feet of land, as well as through 2800 feet of land and 8000 feet of water. Other experiments followed on the 28th of July and the 5th of August, as well as on the 14th of August of the same year, proving the instantaneous transmission of the fluid; while a year later, August 5, 1748, additional observations were made, through 12,276 feet of wire, at Shooter’s Hill, showing again that the time occupied in the passage of the electricity was “altogether inappreciable.” Regarding these experiments, Prof. Musschenbroek wrote to Dr. Watson, “_Magnificentissimis tuis experimentis superasti conatus omnium_.”

Watson’s experiments were repeated, notably by Franklin, across the Schuylkill at Philadelphia, in 1748; by Deluc, across the Lake of Geneva, in 1749; and by Winckler, at Leipzig, in 1750. It is said that Lemonnier (A.D. 1746) produced shocks at Paris through 12,789 feet of wire and that Bétancourt (A.D. 1795) discharged electric jars through a distance of twenty-six miles.

To Dr. Watson is also due the first demonstration of the passage of electricity through a vacuum. Noad tells us that he caused the spark from his conductor to pass in the form of coruscations of a bright silver hue through an exhausted tube three feet in length, and he discharged a jar through a vacuum interval of ten inches in the form of “a mass of very bright embodied fire.” These demonstrations were repeated and varied by Canton, Smeaton and Wilson.

His experiments in firing gunpowder, hydrogen, etc., by the electric spark, are detailed at p. 78 of Priestley’s “History,” etc., London, 1775.

Watson was rewarded with the Copley medal for his researches in electricity, which brought him also honorary degrees from two German universities. He was knighted in 1786, one year before his death.

REFERENCES.--“Watson’s Experiments and Observations on
Electricity,” 1745, also his “Account of the Experiments made
by some gentlemen of the Royal Society,” etc., 1748; _Phil.
Trans._, Vol. XLIII. p. 481; Vol. XLIV. pp. 41, 388, 695,
704; Vol. XLV. pp. 49–120, 491–496; Vol. XLVI. p. 348; Vol.
XLVII. pp. 202, 236, 362, 567; Vol. XLVIII. p. 765; Vol. LI.
p. 394 (lyncurium of the ancients); Vol. LIII. p. 10; also the
following abridgments: Hutton, Vol. IX. pp. 151, 195, 308, 368,
408, 410, 440, 553; Vol. X. pp. 12, 189, 197, 227, 233, 242,
303, 372–379, 525; Vol. XI. p. 419 (lyncurium of the ancients),
580, 660, 679; Vol. XII. p. 127; John Martyn, Vol. X. part
ii. pp. 279–280, 290, 294, 329, 339, 347, 368, 407, 410. See
likewise, _Scientific American Supplement_ of Oct. 5, 1889, No.
718, pp. 11, 471, for an interesting engraving of Dr. Watson’s
experiment made through the water of the Thames, as well as for
a detailed account of Lemonnier’s experiment above referred to.
For Mr. A. Trembley, consult _Phil. Trans._, Vol. XLIV. p. 58,
and John Martyn’s abridgments, Vol. X. part ii. p. 321.

=A.D. 1746.=--Lemonnier (Pierre Claude Charles), a distinguished savant, who was member of the French Academy as adjunct geometrician before he had attained his twenty-first year and became foreign member of the English Royal Society three years later, was the first scientist who drew electricity from the narrow domain of the laboratory.

He confirmed the result previously obtained by Grey (A.D. 1720) that electric attraction is not proportioned to the mass or quantity of matter in bodies, but only to the extent of their surface, length having greater effect than breadth (_Phil. Trans._, Vol. XLIV for 1746, p. 290; Snow Harris, “Treatise on Frict. Elect.,” London, 1867, p. 239, and “Hist. de l’Acad.,” 1746). He found that an anvil weighing two hundred pounds gives but an inconsiderable spark, while the spark from a tin speaking-trumpet eight or nine feet long, but weighing only ten pounds, is almost equal to the shock of the Leyden phial. A solid ball of lead, four inches in diameter, gives a spark of the same force as that obtained from a thin piece of lead of like superficies bent in the form of a hoop. He took a thin and long piece of lead, and noticed that when it was electrified in its whole length it gave a very strong spark, but a very small one when it was rolled into a lump (_Ac. Par._, 1746, M. p. 369). It had likewise been shown by Le Roi and D’Arcy that a hollow sphere accepted the same charge when empty as when filled with mercury, which latter increased its weight sixtyfold; all proving the influence of _surface_ as distinguished from that of mass (Tyndall, Notes on Lecture IV).

Lemonnier discovered that electricity is ever present in the atmosphere, that it daily increases in quantity from sunrise till about three or four o’clock in the afternoon, diminishing till the fall of dew, when it once more increases for a while, and finally diminishes again before midnight, when it becomes insensible. He observed a continual diminution of electricity as the rain began to fall, and he says: “When the wire was surrounded with drops of rain, it was observed that only some of them were electrical, which was remarkable by the conic figure they had; whilst the others remained round as before. It was also perceived that the electrical and non-electrical drops succeeded almost alternately; this made us call to mind a very singular phenomenon which happened some years before, to five peasants who were passing through a cornfield, near Frankfort upon the Oder, during a thunderstorm; when the lightning killed the first the third and the fifth of them, without injuring the second or the fourth” (_Phil. Trans._, Vol. XLVII. p. 550).

REFERENCES.--Le Monnier, “Lois du Magnétisme,” Paris, 1776–1778;
_Phil. Trans._, Vol. XLIV. p. 247; Vol. XLVIII. part i. p.
203; “Journal des Sçavans,” Vol. CXII for 1737, p. 73; also
Hutton’s abridgments, Vol. IX. pp. 275, 308, 368, 591 (biogr.);
John Martyn’s abridgments, Vol. X. part ii. pp. 329–348;
“Philosophical Magazine,” Vol. VI. for 1800, p. 181, “Some
Account of the Late P. C. Le Monnier,” 1715–1799; “Mémoires de
l’Institut Nat. des Sc. et des Arts,” Hist. An. IX. p. 101;
_Mémoires de l’Acad. Royale des Sciences_, 1746, pp. 14–24, 447,
671–696; 1752, Tome I. pp. 9–17, Tome II. 233–243, 346–362;
1770, p. 459; Bertholon, “Elec. du Corps Humain,” 1786, Vol.
I. pp. 10–14; Harris, “Frict. Elec.,” p. 239; _Sc. American
Supplement_, for Oct. 5, 1889, No. 718, pp. 11, 471. See also
reports of the experiments of G. B. Beccaria, G. F. Gardini (“De
inflexu,” etc., ss. 50, 51), Andrew Crosse and others at “Bibl.
Britan. Sc. et Arts,” 1814, Vol. LVI. p. 524.

=A.D. 1746.=--Bevis (John), English astronomer and Secretary of the Royal Society, first suggested to Dr. Watson the external coating of the Leyden jar with tinfoil or sheet-lead, and was likewise the first to observe that the force of the charge increases as larger jars are employed, but not in proportion to the quantity of water they contain. As water only played the part of a conductor, he rightly thought that metal would do equally well, and he therefore filled three jars with leaden shot instead of with water. When the metallic connection was made it was found that the discharge from three jars was greater than that from two and the discharge from two much greater than that from one. This showed that the seat of the electric force is the surface of the metal and the glass, and proves that the force of the charge is in proportion to the quantity of coated surface.

Thus to Dr. Bevis belongs the credit of having constructed the first electric battery, although the honour has been claimed by the friends of Daniel Gralath (A.D. 1747).

REFERENCES.--_Phil. Trans._, abridged, Vol. X. pp. 374, 377;
Wilson, “Treatise,” London, 1752, Prop. XVII. p. 107.

=A.D. 1746.=--Le Cat (Claude Nicolas), a physician of Rouen, observed, when suspending several pieces of leaf gold at his conductor, that they hung at different distances according to their sizes, the smallest pieces placing themselves nearest the conductor and the largest farthest from it.

Le Cat (1700–1768) became celebrated for his surgical operations and succeeded in carrying off all the first prizes offered by the Royal Academy of Surgeons between the years 1734 and 1738 inclusively. Consult his different works named at p. 292 of Ronalds’ “Catalogue”; “Histoire de l’Electricité,” pp. 84 and 85; “Biographie Générale,” Vol. XXX. pp. 179–182.

=A.D. 1746.=--Maimbray (M.), of Edinburgh, electrified two myrtle trees, during the entire month of October 1746, and found that they put forth small branches and blossoms sooner than other shrubs of the same kind which had not been electrified. This result was confirmed by the Abbé Nollet, who filled two pots with vegetating seeds and found that the pot which he had constantly electrified for fifteen consecutive days put forth earlier sprouts as well as more numerous and longer shoots than did the other.

Like experiments were at the same time carried on with equal success by M. Jallabert and M. Boze, as well as by the Abbé Menon, Principal of the College of Bueil at Angers, France. The last named also found that electricity increases the insensible perspiration of animals. He chose cats, pigeons and chaffinches, and observed after they were electrified, that one cat was sixty-five or seventy grains lighter than the other, the pigeon from thirty-five to thirty-eight grains, and the chaffinch had lost six or seven grains. He also electrified a young person between the ages of twenty and thirty, for five hours and found a loss in weight of several ounces.

With reference to the effect of electricity on different varieties of growing plants, a paper in Boston not long ago published the following:

“In the last few years some very interesting experiments in
gardening by electricity have been made by Prof. Selim Lemström,
of the University of Helsingfors. These have been carried out
both upon the potted plants in the hot-house and upon plants in
the open field, the insulated wires in the latter case being
stretched upon poles over the plot of ground, and provided
with a point for each square metre of area. The current has
been supplied by Holtz machines run from eight to eighteen
hours daily, the positive pole being connected with the network
of wires and the negative with a zinc plate buried in the
ground. The electric influence was scarcely perceptible in
the growing plants, but was very marked in the yield of many
species, especially of barley and wheat, of which the crop was
increased by half in some cases. In the hot-house the maturity
of strawberries was greatly advanced. The results have shown
that plants may be divided into two groups: one, the development
of which is favoured by electricity, comprising wheat, rye,
barley, oats, red and white beets, parsnips, potatoes,
celeriac, beans, raspberries, strawberries and leeks; and the
other, whose development is more or less interfered with by
electricity, including peas, carrots, kohlrabi, rutabagas,
turnips, white cabbages and tobacco. The more fertile the soil,
and consequently the more vigorous the vegetation, the greater
has been the excess of the crop under electric influence. Prof.
Lemström’s experiments up to 1887 were carried on in Finland,
but he has since repeated his work in France, and demonstrated
that the electric influence is the same in any climate, though
likely to be injurious under a scorching sun.”

REFERENCES.--Nollet, “Recherches sur l’Electricité,” pp. 366,
382; _Phil. Trans._, abridged, Vol. X. p. 384; _Electrical
Review_, London, June 5, 1891, p. 707.

=A.D. 1746.=--Knight (Gowan or Gowin), F.R.S., an English physician, is the first to make very powerful steel magnets. The method, which he long succeeded in keeping secret, was described after his death, in the _Phil. Trans._ for 1746–1747, Vol. XLIV. It consists of placing two magnets in the same straight line, with their opposite poles close to or very near each other, and in laying under them the bar to be magnetized after having it tempered at a cherry-red heat. The magnets are then drawn apart in opposite directions along the bar, so that the south pole of one magnet passes over the north polar half, and the north pole of the other magnet passes over the south polar half of the bar.

This was how Dr. Knight made the bars of the two great magnets of the Royal Society. Each magnet contained two hundred and forty bars, fifteen inches long, one inch wide and half an inch thick. Dr. Robison described, in 1800, the effect of pressing together the dissimilar poles of the two magnets, and, thirty years later, Prof. Faraday, upon placing a soft iron cylinder, one foot long and three-quarters of an inch in diameter, across the dissimilar poles, found that he required a force of one hundred pounds to break down the attractive power.

Previously to Dr. Knight’s discovery, the method of making artificial magnets most in use was by simply rubbing the bar to be magnetized upon one of the poles of a natural magnet in a plane at right angles to the line joining its two poles.

Another secret of Dr. Knight was also, after his death, made known to the Royal Society by its secretary, Mr. Benjamin Wilson. It was the mode of making artificial paste magnets. He collected a large quantity of iron filings, which he cleansed and made into a fine powder under water and afterward dried and mixed, preferably with linseed oil. This was baked into cakes, which were magnetized by placing them between the ends of his magazine of artificial magnets.

To Dr. Knight was given the first English patent in the Class of Electricity and Magnetism. It bears date June 10, 1766, No. 850, and is for the construction of “Compasses so as to prevent them being affected by the motion of the ship,” etc.

REFERENCES.--_Phil. Trans._, Vol. XLIII. pp. 161, 361; Vol.
XLIV. p. 656; Vol. XLIX. p. 51; Vol. LXVI. p. 591; C. R. Weld,
“Hist. of Roy. Soc.,” Vol. I. p. 511; Noad, “Manual,” 1859, p.
593; Sturgeon, “Sc. Researches,” Bury, 1850, p. 249; also the
abridgments by Hutton, Vol. IX. pp. 71, 74, 122, 390 (Folkes),
653; Vol. X. pp. 64, 67; Vol. XIV. pp. 117, 480; and by John
Martyn, Vol. X. part ii. pp. 678–698.

=A.D. 1746.=--Gravesande (Wilhelm Jacob), celebrated Dutch mathematician and natural philosopher (1688–1742), whose family name was Storen Van ’Sgravesande, is the author of “Eléments de physique démontrés mathématiquement ... ou introduction à la philosophie Newtonienne,” which was translated from the Latin and published at Leyden in 1746.

At p. 87 of the second volume of the last-named work he gives a description of an electrical machine constructed on the plan of that of Hauksbee. It consisted merely of a crystal globe, which was mounted upon a copper stand, and against which was pressed the hand of the operator while it was made to revolve rapidly by means of a large wheel.

Gravesande taught publicly on the Continent the philosophy of Newton, and, by so doing, was one of the first to bring about a revolution in the domain of physical sciences generally. His original “Physices Elementa Mathematica,” as well as his “Philosophiæ Newtonianæ,” etc., and “Introductio ad Philosophiam,” etc., were respectively published at Leyden in 1720, 1723 and 1736.

REFERENCE.--Houzeau et Lancaster, “Bibl. Générale,” Vol. II. p.
252.

=A.D. 1746.=--Nollet (Jean Antoine), a distinguished French philosopher (1700–1770), to whom was given the title of Abbé while holding deacon’s orders, is the first in France to make experiments with the Leyden jar.

While in Paris he applied himself to electrical studies in company with Charles Dufay (already noticed at A.D. 1733), and made such ingenious experiments that René de Réaumur allowed him the free use of his extensive apparatus and laboratory. During the month of April 1746, he transmitted, in the presence of the French King, an electrical shock from a small phial through a chain of one hundred and eighty of the Royal Guards, and at the Carthusian Convent, not long afterward, he sent a shock through a line of monks stretched a distance of over a mile, causing them all to experience instantaneously the same sensation.

Nollet’s work, “Essai sur l’électricité des corps,” was originally published at Paris in 1746. He was the first to observe that pointed bodies electrified give out streams of light (the smallest points displaying “brushes of electric light”), but that they do not exhibit as powerful indications of electricity as are shown by blunt bodies. He also found that glass and other non-conductors are more strongly excited in air than _in vacuo_; that the electric spark is more diffuse and unbroken _in vacuo_; and that an excited tube loses none of its electricity by being placed in the focus of a concave mirror when the sunlight is therein concentrated.

His experiments upon the evaporation of fluids by electricity, as well as upon the electrification of capillary tubes full of water (observed also by Boze), and upon the electrification of plants and animals, are detailed in his “Recherches,” etc., pp. 327, 351, 354–356, while his observations upon the electrical powers of different kinds of glass are given in the sixth volume of the “Leçons de Physique Expérimentale,” issued in 1764.

As has been truly said, it is no easy matter to form an adequate idea of Nollet’s theory of electricity, which was opposed at the time by almost all the eminent electrical philosophers of Europe. He asserted that when an electric is excited, electricity flows to it from all quarters, and when it is thus _affluent_, it drives light bodies before it. Hence the reason why excited bodies attract. When the electricity is _effluent_ the light bodies are of course driven from the electric, which in that condition appears to repel. He therefore believed every electric to be possessed of two different kinds of pores, one for the emission of the electric matter, and the other for its reception.

Nollet is the first one who published the close relationship existing between lightning and the electric spark. This he did during the year 1748, in the fourth volume of his “Leçons,” already alluded to and from which the following is extracted: “If any one should undertake to prove, as a clear consequence of the phenomenon, that thunder is in the hands of nature what electricity is in ours--that those wonders which we dispose at our pleasure are only imitations on a small scale of those grand effects which terrify us, and that both depend on the same mechanical agents ... I confess that this idea, well supported, would please me much.... The universality of the electric matter, the readiness of its actions, its instrumentality and its activity in giving fire to other bodies, its property of striking bodies, externally and internally, even to their smallest parts ... begin to make me believe that one might, by taking electricity for the model, form to one’s self, in regard to thunder and lightning, more perfect and more probable ideas than hitherto proposed.”

For a memoir treating of the cause of thunder and lightning, written by the Rev. Father de Lozeran de Fech, of Perpignan, the Bordeaux Academy of Sciences had in 1726 awarded him its annual prize; and the same institution conferred a similar award, in August 1750, upon M. Bergeret, a physician of Dijon, whose memoir admitted the close analogy between lightning and electricity.

REFERENCES.--Ronalds’ “Catalogue,” pp. 369–371; Jean Morin,
“Réplique,” Paris, 1749; A. H. Paulian, “Conjectures,” 1868;
“Abrégé des transactions philosophiques,” Vol. X. p. 336;
“Mémoires de mathématique,” etc., pour 1746, p. 22; “Journal des
Sçavans,” Vol. CXVII. for 1739, pp. 111–115, and Vol. CXLII for
1747, pp. 248–265; “Medical Electricity,” by Dr. H. Lewis Jones,
Philad., 1904, p. 2; “Mémoires de l’Acad. Royale des Sciences”
pour 1745, p. 107; 1746, p. 1; 1747, pp. 24, 102, 149, 207;
1748, p. 164; 1749, p. 444; 1753, pp. 429, 475; 1755, p. 293;
1761, p. 244; 1762, pp. 137, 270; 1764, pp. 408–409; 1766, p.
323; “Leçons,” eighth edition, Vol. IV. p. 315; _Phil. Trans._,
Vol. XLV. p. 187; Vol. XLVI. p. 368; Vol. XLVII. p. 553; also
the following abridgments: Hutton, Vol. X. pp. 20, 295, 372–379,
446 (Dr. Birch); Vol. XI. p. 580; John Martyn, Vol. X. part ii.
pp. 277–333, 382 (Folkes), 414. See the experiments of Etienne
François du Tour, “Sur la manière dont la flamme agit sur les
corps electriques,” in a letter addressed by him to Nollet in
1745, and in “Mém. de Mathém. et Phys.,” Vol. II. p. 246, Paris,
1755; also Zantedeschi and Faraday on the “Magnetic Condition of
Flame” (Faraday’s “Exper. Res.,” Vol. III. pp. 490–493).

=A.D. 1746.=--Wilson (Benjamin) (1721–1788), Secretary to the Royal Society, writes his “Essay toward an explication of the phenomena of Electricity deduced from the ether of Sir Isaac Newton.” In the chapter of Priestley’s “History” treating of the Theories of Electricity, he says: “With some, and particularly Mr. Wilson, the chief agent in all electrical operations is Sir Isaac Newton’s ether, which is more or less dense in all bodies in proportion to the smallness of their pores, except that it is much denser in sulphureous and unctuous bodies. To this ether are ascribed the principal phenomena of attraction and repulsion, whereas the light, the smell, and other sensible qualities of the electric fluid are referred to the grosser particles of bodies, driven from them by the forcible action of this ether. Many phenomena in electricity are also attempted to be explained by means of a subtile medium, at the surface of all bodies, which is the cause of the refraction and reflection of the rays of light, and also resist the entrance and exit of this ether. This medium, he says, extends to a small distance from the body, and is of the same nature with what is called the electric fluid.[50] On the surface of conductors this medium is rare and easily admits the passage of the electric fluid, whereas on the surface of electrics it is dense and resists it. This medium is rarefied by heat, which converts non-conductors into conductors.”

At pp. 71 and 88, 1746 edition, and at p. 88, Prop. XI. of the 1752 edition of this same “Essay,” Wilson says that during the year 1746 he discovered a method of giving the shock of the Leyden jar to any particular part of the body without affecting any other portion; that he increased the shock from the jar by plunging it into water, thereby giving it a coating of water on the outside as high as it was filled on the inside; and that the accumulation of electricity in the Leyden jar is always in proportion to the thinness of the glass, the surface of the glass and that of the non-electrics in contact with the inside and outside thereof.

It was in this same year, 1746, that Wilson first observed the _lateral shock_ or _return stroke_, which was not, however, explained until Lord Mahon, third Earl of Stanhope, published his “Principles of Electricity,” in 1779.

On the 13th of November, 1760, a paper of Mr. Wilson’s was read before the Royal Society, in which he detailed several of his ingenious experiments on the _plus_ and _minus_ of electricity, and showed that these can be produced at pleasure by carefully attending to the form of bodies, their sudden or gradual removal and the degrees of electrifying. He had previously noticed that when two electrics are rubbed together, the body whose substance is hardest and electric power strongest is always electrified positively and the other negatively. Rubbing the tourmaline and amber together he produced a _plus_ electricity on both sides of the stone and a _minus_ on the amber; but, rubbing the diamond and the tourmaline, both sides of the tourmaline were electrified _minus_ and the diamond _plus_. When insulated silver and glass were rubbed, the silver became _minus_ and the glass _plus_.

He further observed that when directing a stream of air against a tourmaline, a pane of glass or a piece of amber, these were electrified _plus_ on both sides. Prof. Faraday subsequently showed that no electrical effect is produced in these cases unless the air is either damp or holds dry powders in suspension, the electricity being produced by the friction of particles of water in the one case and by the particles of powder in the other. Sir David Brewster, who thus mentions the latter fact, likewise singles out two more of Mr. Wilson’s observations, viz. that when a stick of sealing-wax is broken across or when a dry, warm piece of wood is rent asunder, one of the separated surfaces becomes vitreously and the other resinously electrified.

REFERENCES.--De La Rive, “Electricity,” Vol. I. p. 203; Wilson,
“Treatise on Electricity”; Wilson and Hoadley, “Observations
on a Series of Electrical Experiments”; _Phil. Trans._, Vol.
XLVIII. p. 347; Vol. XLIX. p. 682; Vol. LI. part i. pp. 83, 308,
331, part ii. p. 896; Vol. LIII. pp. 436, etc.; Vol. LXVIII.
p. 999; Vol. LXIX. p. 51; also Hutton’s abridgments; Vol. X.
p. 420; Vol. XI. pp. 15, 396, 504; Vol. XII. pp. 44, 147; Vol.
XIII. p. 374; Vol. XIV. pp. 334, 337, 458, 480; “The Electrical
Researches of the Hon. Henry Cavendish,” Cambridge, 1879, No.
125; L. E. Kaemtz, “Lehrbuch der Meteor,” Halle, 1832, Vol. II.
p. 395.

=A.D. 1746.=--Ellicott (John), of Chester, suggests a method of estimating the exact force of the electric charge contained in the Leyden jar by its power to raise a weight in one scale of a balance while the other scale is held over and attracted by the electrified body. This was the principle upon which Mr. Gralath constructed the electrometer shown in _Dantzig Memoirs_, Vol. I. p. 525.

With reference to the experiments of Boze (A.D. 1738) and of Nollet (A.D. 1746) made with capillary tubes, he says that the siphon, though electrified, will only deliver the water by drops if the basin containing the water is also electrified. He explains Nollet’s observation, that the electric matter issues more sensibly from the point at the extremity of the conductor, by saying that the effluvia, in rushing from the globe along the conductor, as they approach the point are brought nearer together, and therefore are denser there, and if the light be owing to the density and velocity of the effluvia it will be visible at the point and nowhere else. Ellicott’s theory of electricity is founded upon the following data: (1) electrical phenomena are produced by effluvia; (2) these effluvia repel each other; (3) they are attracted by all other matter. If the word _fluid_ is substituted for effluvia, these data absolutely agree with those adopted by Æpinus and Cavendish, forming the basis of the only satisfactory theory of electricity hitherto proposed.

REFERENCES.--Boulanger, “Traité de la Cause et des phénomènes de
l’électricité,” Paris, 1750, p. 324; _Phil. Trans._ for 1746,
Vol. XLIV. p. 96, and for 1748, Vol. XLV. pp. 195–224, 313; also
the abridgments of John Martyn, Vol. X. part ii. pp. 324, 386,
389, 394; Hutton, Vol. IX. p. 475.

=A.D. 1747.=--Pivati (Johannes Francisco), a Venetian physician, relates in his “Lettere della elettricita medica,” that if odorous substances are confined in glass vessels and the latter excited, the odours and other medical virtues will transpire through the glass, infect the atmosphere of a conductor, and communicate the virtue they may possess to all persons in contact therewith; also, that those substances held in the hands of persons electrified will communicate their virtue to them so that medicines can thus be made to operate without being taken in the usual manner.

This appears to have been likewise asserted especially by M. Veratti, of Bologna, and by M. Bianchi, of Turin; also by Prof. Winckler, of Leipzig, who satisfied himself of the power of electricity on sulphur, cinnamon, and on balsam of Peru even at a distance.

By the above-named means of applying the electric fluid Pivati is reported to have effected cures of ordinary pains and aches, and to have even relieved of gout the old Bishop Donadoni, of Sebenico, who had long been a sufferer, and who was at the time seventy-five years of age. This pretended transudation and its medical effects could not, however, be verified, even with the directions asked of and given by Prof. Winckler, when very careful and exhaustive experiments were made, on the 12th of June, 1751, at the house of Dr. Watson, in presence of the president and other officers as well as friends of the Royal Society. Nor could Dr. Bianchini, Professor of Medicine at Venice, succeed any better. At a later date, Franklin asserted that it was impossible to combine the virtues of medicines with the electric fluid.

REFERENCES.--Franklin’s Letters, p. 82; _Phil. Trans._ for 1748,
Vol. XLV. pp. 262, 270; for 1750, Vol. XLVI. pp. 348, 368; for
1751, Vol. XLVII. p. 231; for 1753, Vol. XLVIII. pp. 399, 406,
and Vol. X. abridged, pp. 400–403.

=A.D. 1747.=--Louis (Antoine), eminent French surgeon (1723–1792), publishes “Observations sur l’électricité,” of which the first issue appeared in 1747 and wherein he indicates the employment of electricity in medical practice. This he did again in his “Recueils,” upon a more pretentious scale, six years later, 1753.

REFERENCES.--N. F. J. Eloy, “Dict. de la Médecine,” Mons, 1778,
Vol. III. p. 206; “Gen. Biog. Dict.” of Alex. Chalmers, 1815,
Vol. XX. p. 419; Hœfer, “Nouv. Biog. Gén.,” Vol. XXXI. p. 1033;
Quérard, “La France Littéraire”; “Biog. Univ.,” de Michaud, Vol.
XXV. pp. 319–325.

=A.D. 1747.=--Gralath (Daniel) publishes in the _Dantzig Memoirs_ his “Geschichte der Electricität.”

He is the first to construct a Leyden phial with a long, narrow neck, through which is passed an iron wire bearing a tin knob in place of the iron nail theretofore used; and, with several of these phials joined together in the form of a battery, he had, during the previous year, transmitted a shock through a chain of twenty persons. His observations are recorded in the above-named _Memoirs_ at pp. 175–304 and 506–534, Vol. I.; pp. 355–460, Vol. II.; pp. 492–556, Vol. III. Gralath’s “Electrische Bibliothek” is in Vols. II. and III.

=A.D. 1747.=--The Swedish mathematician and philosopher, Samuel Klingenstierna, and his pupil, M. Stroemer, were the first who properly electrified by the rubber, and their experiments were published in the Acts of the Royal Academy of Sciences at Stockholm for the year 1747 (see Priestley’s “History of Electricity,” Part I. period viii. s. 3, wherein he alludes to Wilcke’s “Herrn Franklin’s briefe,” etc., p. 112).

=A.D. 1748.=--Morin (Jean), French physicist, publishes at Chartres “Nouvelle dissertation sur l’électricité des corps,” etc., in which he details many of his experiments, and endeavours to give a correct explanation of all the extraordinary electrical phenomena hitherto observed. He is also the author of a “Reply to Mr. Nollet upon Electricity,” published in 1749 at Chartres and at Paris, as well as of a treatise upon Universal Mechanism, which latter, according to the _Journal des Savants_, contained more information upon Nature generally, and expressed in fewer words, than was embraced in any previous work.

REFERENCES.--“Dict. Univ.,” Vol. XI. p. 568; “Biog. Générale,”
Vol. XXXVI. p. 599.

=A.D. 1749.=--Stukeley (the Rev. William), M.D., is the first who advanced that earthquakes are probably caused by electricity. This he did in a paper read before the Royal Society, March 22, 1749, having reference to the subterranean disturbances noticed in London, February 8 and March 8 of the same year. In this communication, as well as in a subsequent one read to the same Society, December 6, 1750, bearing upon a similar disturbance observed throughout England during the previous month of September, he explains why earthquakes are not the result of subterraneous winds, fires, vapours, etc.

One of his strongest arguments is that no such vapours could instantaneously have destroyed thirteen great cities as did the earthquake which occurred in Asia Minor, A.D. 17, and which is reckoned to have shaken a cone of earth three hundred miles diameter in base and two hundred miles in the axis. This quantity of earth, he says, “all the gunpowder which has ever been made since the invention of it would not have been able to stir, much less any vapours, which could be supposed to be generated so far below the surface,” and, he adds, “if the concussion depended upon a subterraneous eruption the shock would precede the noise.”

He observes that the earth for months prior to the afore-named disturbances “must have been in a state of electricity ready for that particular vibration in which electrification exists”; that all the vegetation had been “uncommonly forward ... and electricity is well known to quicken vegetation”; that the aurora borealis had been very frequent about the same time and had been twice repeated just before the earthquake, “of such colours as had never been seen before,” there being, one evening, “a deep red aurora borealis covering the cope of heaven very terrible to behold”; that the whole year had been “remarkable for fire-balls, thunder, lightning and coruscations, almost throughout all England,” all which “are rightly judged to proceed from the electrical state of the atmosphere”; and, finally, that, a little before the earthquake, “a large and black cloud suddenly covered the atmosphere, which probably occasioned the shock by the discharge of a shower.” He adds that, according to Dr. Childrey, earthquakes are always preceded by rain and sudden tempests of rain in times of great drought.

Dr. Stephen Hales (1677–1761), who was Stukeley’s classmate at Bennet College, Cambridge, and later his chief assistant in the study of the natural sciences, and who afterward became celebrated for his physical investigations and discoveries, arrives at a like conclusion. He thinks that “the electric appearances were only occasioned by the great agitation which the electric fluid was put into by the shock of so great a mass of the earth.” The great noise which attended the disturbance of March 8, 1749, he conjectured was “owing to the rushing or sudden expansion of the electric fluid at the top of St. Martin’s spire, where all the electric effluvia, which ascended along the large body of the tower, being strongly condensed, and accelerated at the point of the weathercock, as they rushed off made so much the louder expansive explosion.” It may be added here that Dr. Hales is the one who, at a previous date, had communicated to the Royal Society his observation of the fact that the electric spark proceeding from warm iron is of a bright, light colour, while that from warm copper is green, and the colour from a warm egg of a light yellow. In his opinion, these experiments appeared to argue that some particles of those different bodies are carried off in the electric flashes wherein those different colours are exhibited.

For Stephen Hales, consult the _Phil. Trans._, Vol. XLV. p. 409, as well as the abridgments of Hutton, Vol. IX. p. 534, and for his portrait see “Essays in Historical Chemistry,” by T. E. Thorpe, London, 1894.

For Stukeley and for Stephen Hales: consult “General Biographical Dictionary,” Alex. Chalmers, London, 1814, Vol. XVII. pp. 41–43.

REFERENCES.--Priestley, “History of Electricity,” Part I. period
x. s. 12; _Phil. Trans._, abridged by John Martyn, Part II.
of Vol. X. pp. 406–526, 535, 540, 541, 551; Vol. XLIV-XLV, p.
409; Appendix to the _Phil. Trans._ for 1750, Vol. XLVI; Hale,
“Statical Essays,” II. p. 291; Thomson, “Hist. Roy. Soc.,” 1812,
p. 197.

=A.D. 1749.=--Jallabert (Jean Louis), Professor of Philosophy and Mathematics at Geneva, is the author of “Expériences sur l’électricité, avec quelques conjectures sur la cause de ses effets,” of which a smaller edition had appeared at Geneva in 1748.

He confirms the result obtained by Dr. Watson (A.D. 1745) that the electric fluid takes the shortest course by passing through the substance of a conducting wire instead of along its surface. By making his Leyden experiments with a jar in which the water is frozen, he shows that ice is a conductor of electricity. He improves upon Nollet’s experiments, and demonstrates conclusively that plants which are electrified grow faster and have finer stems, etc., than those not electrified. He is the first to observe that a body pointed at one end and round at the other produces different appearances upon the same body, according as the pointed or the rounded end is presented to it. The _Dantzig Memoirs_, Vol. II. p. 378, tell us that Carolus Augustus Van Bergen, Professor of Medicine at Frankfort on Oder, had previously noticed, “as a small step toward discovering the effect of pointed bodies,” that sparks taken from a polished body are stronger than those from a rough one. With the latter he found it difficult to fire spirits, but he could easily do it with a polished conductor.

M. Jallabert is also known to have effected some medical cures through the agency of the electric fluid, as related in the “Expériences” above alluded to.

REFERENCES.--“Biog. Univ.,” Vol. XX. p. 535; Bertholon, “Elec.
du Corps Humain,” 1786, Vol. I. pp. 260, 292, 299, 334, 413, and
Vol. II. p. 291; Beccaria, “Dell’ Elettricismo Naturale,” etc.,
p. 125; “Journal des Sçavans,” Vol. CXLIX. for 1749, pp. 1–18,
441–461; “Medical Electricity,” by Dr. H. Lewis Jones, Philad.
1904, p. 2.

=A.D. 1749.=--Mines are fired by electricity (S. P. Thompson, lecture delivered October 7, 1882, at the University College, Bristol).

=A.D. 1749.=--Through the important work entitled “Traité sur l’Electricité,” Louis Elisabeth de la Vergne Tressan secures, a year later, admission to both the French Académie des Sciences and the English Royal Society. During 1786, three years after his death, the above-named work was merged into a publication in two volumes under the title of “Essai sur le fluide électrique considéré comme agent universel.”

REFERENCES.--“Biographie Générale,” Vol. XLV. pp. 623–626;
Larousse, “Dictionnaire Universel,” Vol. XV. p. 474.

=A.D. 1749.=--Duhamel (Henri Louis, du Monceau) (1700–1782), member of the French Royal Academy of Sciences, develops, in conjunction with M. Antheaulme, the method introduced by Gowin Knight (A.D. 1746) for making artificial magnets, which latter process was found to be defective when applied to very large bars. To Le Maire, however, is due (_Mem. de l’Acad. de Paris_, 1745 and 1750), the notable improvement which consists in magnetizing at the same time two steel bars of any shape by placing them parallel to each other and connecting their extremities, with pieces of soft iron placed at right angles, in order to form a closed rectangular parallelogram. Two strong magnets, or two bunches of small magnetic bars, with their similar poles together, are then applied to the centre of one of the bars to be magnetized and are drawn away from each other, practically as in Dr. Knight’s method, while being held at an inclination of about forty-five degrees. The operation is repeated upon the other bar and continued alternately until sufficient magnetism is imparted to both, it being borne in mind that before the treatment is given to the second bar the poles must in each instance be reversed, _i. e._ the pole which was to the right hand should be turned to the left. The entire operation is to be repeated upon the reverse side of both bars.

REFERENCES.--Harris, “Rudim. Magn.,” I. and II. pp. 85 and 86;
P. Larousse, “Dict. Univ.,” Vol. VI. p. 1363; “Biog. Générale,”
Vol. XV. pp. 106–107; Condorcet, “Eloge de Duhamel”; I. M. Des
Essarts, “Siècles littéraires”; Georges Cuvier, “Hist. des Sc.
Naturelles,” Vol. V; Thos. Thomson, “Hist. of the Roy. Soc.,”
London, 1812, p. 45.

=A.D. 1750–1753.=--In M. Arago’s “Historical Eloge of James Watt,” translated by James P. Muirhead and published in London during the year 1839, it is said, at p. 6, that Watt constructed, at about the period first mentioned herein, a small electrical (his earliest) machine, the brilliant sparks from which became a subject of much amusement and surprise to all the companions of the poor invalid (“James Watt,” by Andrew Carnegie, New York, 1905).