The Botanic Garden Volume I Part 2

Trans. Vol. LXV. And are so divided by membranes as to compose a very extensive surface, and are supplied with many pairs of nerves larger than any other nerves of the body; but how so large a quant.i.ty is so quickly acc.u.mulated as to produce such amazing effects in a fluid ill adapted for the purpose is not yet satisfactorily explained. The Torpedo possesses a similar power in a less degree, as was shewn by Mr. Walch, and another fish lately described by Mr. Paterson. Philo. Trans. Vol.

LXXVI.

In the construction of the Leyden-Phial, (as it is called) which is coated on both sides, it is known, that above one hundred times the quant.i.ty of positive electricity can be condensed on every square inch of the coating on one side, than could have been acc.u.mulated on the same surface if there had been no opposite coating communicating with the earth; because the negative electricity, or that part of it which caused its expansion, is now drawn off through the gla.s.s. It is also well known, that the thinner the gla.s.s is (which is thus coated on both sides so as to make a Leyden-phial, or plate) the more electricity can be condensed on one of its surfaces, till it becomes so thin as to break, and thence discharge itself.

Now it is possible, that the quant.i.ty of electricity condensible on one side of a coated phial may increase in some high ratio in respect to the thinness of the gla.s.s, since the power of attraction is known to decrease as the squares of the distances, to which this circ.u.mstance of electricity seems to bear some a.n.a.logy. Hence if an animal membrane, as thin as the silk-worm spins its silk, could be so situated as to be charged like the Leyden bottle, without bursting, (as such thin gla.s.s would be liable to do,) it would be difficult to calculate the immense quant.i.ty of electric fluid, which might be acc.u.mulated on its surface.

No land animals are yet discovered which possess this power, though the air would have been a much better medium for producing its effects; perhaps the size of the necessary apparatus would have been inconvenient to land animals.]

[_In his shining claws_. l. 208. Alluding to an antique gem in the collection of the Grand Duke of Florence. Spence.]

V. 1. "NYMPHS! Your soft smiles uncultur'd man subdued, 210 And charm'd the Savage from his native wood; You, while amazed his hurrying Hords retire From the fell havoc of devouring FIRE, Taught, the first Art! with piny rods to raise By quick attrition the domestic blaze, 215 Fan with soft breath, with kindling leaves provide, And lift the dread Destroyer on his side.

So, with bright wreath of serpent-tresses crown'd, Severe in beauty, young MEDUSA frown'd; Erewhile subdued, round WISDOM'S Aegis roll'd 220 Hiss'd the dread snakes, and flam'd in burnish'd gold; Flash'd on her brandish'd arm the immortal shield, And Terror lighten'd o'er the dazzled field.

[_Of devouring fire_. l. 212. The first and most important discovery of mankind seems to have been that of fire. For many ages it is probable fire was esteemed a dangerous enemy, known only by its dreadful devastations; and that many lives must have been lost, and many dangerous burns and wounds must have afflicted those who first dared to subject it to the uses of life. It is said that the tall monkies of Borneo and Sumatra lie down with pleasure round any accidental fire in their woods; and are arrived to that degree of reason, that knowledge of causation, that they thrust into the remaining fire the half-burnt ends of the branches to prevent its going out. One of the n.o.bles of the cultivated people of Otaheita, when Captain Cook treated them with tea, catched the boiling water in his hand from the c.o.c.k of the tea-urn, and bellowed with pain, not conceiving that water could become hot, like red fire.

Tools of steel const.i.tute another important discovery in consequence of fire; and contributed perhaps princ.i.p.ally to give the European nations so great superiority over the American world. By these two agents, fire and tools of steel, mankind became able to cope with the vegetable kingdom, and conquer provinces of forests, which in uncultivated countries almost exclude the growth of other vegetables, and of those animals which are necessary to our existence. Add to this, that the quant.i.ty of our food is also increased by the use of fire, for some vegetables become salutary food by means of the heat used in cookery, which are naturally either noxious or difficult of digestion; as potatoes, kidney-beans, onions, cabbages. The ca.s.sava when made into bread, is perhaps rendered mild by the heat it undergoes, more than by expressing its superfluous juice. The roots of white bryony and of arum, I am informed lose much of their acrimony by boiling.]

[_Young Medusa frowned_. l. 218. The Egyptian Medusa is represented on antient gems with wings on her head, snaky hair, and a beautiful countenance, which appears intensely thinking; and was supposed to represent divine wisdom. The Grecian Medusa, on Minerva's shield, as appears on other gems, has a countenance distorted with rage or pain, and is supposed to represent divine vengeance. This Medusa was one of the Gorgons, at first very beautiful and terrible to her enemies; Minerva turned her hair into snakes, and Perseus having cut off her head fixed it on the shield of that G.o.ddess; the sight of which then petrified the beholders. Dannet Dict.]

2. NYMPHS! YOU disjoin, unite, condense, expand, And give new wonders to the Chemist's hand; 225 On tepid clouds of rising steam aspire, Or fix in sulphur all it's solid fire; With boundless spring elastic airs unfold, Or fill the fine vacuities of gold; With sudden flash vitrescent sparks reveal, 230 By fierce collision from the flint and steel; Or mark with shining letter KUNKEL's name In the pale Phosphor's self-consuming flame.

So the chaste heart of some enchanted Maid Shines with insidious light, by Love betray'd; 235 Round her pale bosom plays the young Desire, And slow she wastes by self-consuming fire.

[_Or fix in sulphur_. l. 226. The phenomena of chemical explosions cannot be accounted for without the supposition, that some of the bodies employed contain concentrated or solid heat combined with them, to which the French Chemists have given the name of Calorique. When air is expanded in the air-pump, or water evaporated into steam, they drink up or absorb a great quant.i.ty of heat; from this a.n.a.logy, when gunpowder is exploded it ought to absorb much heat, that is, in popular language, it ought to produce a great quant.i.ty of cold. When vital air is united with phlogistic matter in respiration, which seems to be a slow combustion, its volume is lessened; the carbonic acid, and perhaps phosphoric acid are produced; and heat is given out; which according to the experiments of Dr. Crawford would seem to be deposited from the vital air. But as the vital air in nitrous acid is condensed from a light elastic gas to that of a heavy fluid, it must possess less heat than before. And hence a great part of the heat, which is given out in firing gunpowder, I should suppose, must reside in the sulphur or charcoal.

Mr. Lavoisier has shewn, that vital air, or Oxygene, looses less of its heat when it becomes one of the component parts of nitrous acid, than in any other of its combinations; and is hence capable of giving out a great quant.i.ty of heat in the explosion of gunpowder; but as there seems to be great a.n.a.logy between the matter of heat, or Calorique, and the electric matter; and as the worst conductors of electricity are believed to contain the greatest quant.i.ty of that fluid; there is reason to suspect that the worst conductors of heat may contain the most of that fluid; as sulphur, wax, silk, air, gla.s.s. See note on l. 174 of this Canto.]

[_Vitrescent sparks_. l. 229. When flints are struck against other flints they have the property of giving sparks of light; but it seems to be an internal light, perhaps of electric origin, very different from the ignited sparks which are struck from flint and steel. The sparks produced by the collision of steel with flint appear to be globular particles of iron, which have been fused, and imperfectly scorified or vitrified. They are kindled by the heat produced by the collision; but their vivid light, and their fusion and vitrification are the effects of a combustion continued in these particles during their pa.s.sage through the air. This opinion is confirmed by an experiment of Mr. Hawksbee, who found that these sparks could not be produced in the exhausted receiver.

See Keir's Chemical Dict. art. Iron, and art. Earth vitrifiable.]

[_The pale Phosphor_. l. 232. See additionable notes, No. X.]

3. "YOU taught mysterious BACON to explore Metallic veins, and part the dross from ore; With sylvan coal in whirling mills combine 240 The crystal'd nitre, and the sulphurous mine; Through wiry nets the black diffusion strain, And close an airy ocean in a grain.-- Pent in dark chambers of cylindric bra.s.s Slumbers in grim repose the sooty ma.s.s; 245 Lit by the brilliant spark, from grain to grain Runs the quick fire along the kindling train; On the pain'd ear-drum bursts the sudden crash, Starts the red flame, and Death pursues the flash.-- Fear's feeble hand directs the fiery darts, 250 And Strength and Courage yield to chemic arts; Guilt with pale brow the mimic thunder owns, And Tyrants tremble on their blood-stain'd thrones.

[_And close an airy ocean_. l. 242. Gunpowder is plainly described in the works of Roger Bacon before the year 1267. He describes it in a curious manner, mentioning the sulphur and nitre, but conceals the charcoal in an anagram. The words are, sed tamen salis petrae _lure mope can ubre_, et sulphuris; et sic facies tonitrum, et corruscationem, si scias, artificium. The words lure mope can ubre are an anagram of carbonum pulvere. Biograph. Britan. Vol. I. Bacon de Secretis Operibus, Cap. XI. He adds, that he thinks by an artifice of this kind Gideon defeated the Midianites with only three hundred men. Judges, Chap. VII.

Chamb. Dict. art. Gunpowder. As Bacon does not claim this as his own invention, it is thought by many to have been of much more antient discovery.

The permanently elastic fluid generated in the firing of gunpowder is calculated by Mr. Robins to be about 244 if the bulk of the powder be 1.

And that the heat generated at the time of the explosion occasions the rarefied air thus produced to occupy about 1000 times the s.p.a.ce of the gunpowder. This pressure may therefore be called equal to 1000 atmospheres or six tons upon a square inch. As the suddenness of this explosion must contribute much to its power, it would seem that the chamber of powder, to produce its greatest effect, should be lighted in the centre of it; which I believe is not attended to in the manufacture of muskets or pistols.

From the cheapness with which a very powerful gunpowder is likely soon to be manufactured from aerated marine acid, or from a new method of forming nitrous acid by means of mangonese or other calciform ores, it may probably in time be applied to move machinery, and supersede the use of steam.

There is a bitter invective in Don Quixot against the inventors of gun- powder, as it levels the strong with the weak, the knight cased in steel with the naked shepherd, those who have been trained to the sword, with those who are totally unskilful in the use of it; and throws down all the splendid distinctions of mankind. These very reasons ought to have been urged to shew that the discovery of gunpowder has been of public utility by weakening the tyranny of the few over the many.]

VI. NYMPHS! You erewhile on simmering cauldrons play'd, And call'd delighted SAVERY to your aid; 255 Bade round the youth explosive STEAM aspire In gathering clouds, and wing'd the wave with fire; Bade with cold streams the quick expansion stop, And sunk the immense of vapour to a drop.-- Press'd by the ponderous air the Piston falls 260 Resistless, sliding through it's iron walls; Quick moves the balanced beam, of giant-birth, Wields his large limbs, and nodding shakes the earth.

[_Delighted Savery_. l. 254. The invention of the steam-engine for raising water by the pressure of the air in consequence of the condensation of steam, is properly ascribed to Capt. Savery; a plate and description of this machine is given in Harris's Lexicon Technic.u.m, art.

Engine. Though the Marquis of Worcester in his Century of Inventions printed in the year 1663 had described an engine for raising water by the explosive power of steam long before Savery's. Mr. Desegulier affirms, that Savery bought up all he could procure of the books of the Marquis of Worcester, and destroyed them, professing himself then to have discovered the power of steam by accident, which seems to have been an unfounded slander. Savery applied it to the raising of water to supply houses and gardens, but could not accomplish the draining of mines by it. Which was afterwards done by Mr. Newcomen and Mr. John Cowley at Dartmouth, in the year 1712, who added the piston.

A few years ago Mr. Watt of Glasgow much improved this machine, and with Mr. Boulton of Birmingham has applied it to variety of purposes, such as raising water from mines, blowing bellows to fuse the ore, supplying towns with water, grinding corn and many other purposes. There is reason to believe it may in time be applied to the rowing of barges, and the moving of carriages along the road. As the specific levity of air is too great for the support of great burthens by balloons, there seems no probable method of flying conveniently but by the power of steam, or some other explosive material; which another half century may probable discover. See additional notes, No. XI.]

"The Giant-Power from earth's remotest caves Lifts with strong arm her dark reluctant waves; 265 Each cavern'd rock, and hidden den explores, Drags her dark coals, and digs her shining ores.-- Next, in close cells of ribbed oak confined, Gale after gale, He crowds the struggling wind; The imprison'd storms through brazen nostrils roar, 270 Fan the white flame, and fuse the sparkling ore.

Here high in air the rising stream He pours To clay-built cisterns, or to lead-lined towers; Fresh through a thousand pipes the wave distils, And thirsty cities drink the exuberant rills.-- 275 There the vast mill-stone with inebriate whirl On trembling floors his forceful fingers twirl.

Whose flinty teeth the golden harvests grind, Feast without blood! and nourish human-kind.

[_Feast without blood!_ l. 278. The benevolence of the great Author of all things is greatly manifest in the sum of his works, as Dr. Balguy has well evinced in his pamphlet on Divine Benevolence a.s.serted, printed for Davis, 1781. Yet if we may compare the parts of nature with each other, there are some circ.u.mstances of her economy which seem to contribute more to the general scale of happiness than others. Thus the nourishment of animal bodies is derived from three sources: 1. the milk given from the mother to the offspring; in this excellent contrivance the mother has pleasure in affording the sustenance to the child, and the child has pleasure in receiving it. 2. Another source of the food of animals includes seeds or eggs; in these the embryon is in a torpid or insensible state, and there is along with it laid up for its early nourishment a store of provision, as the fruit belonging to some seeds, and the oil and starch belonging to others; when these are consumed by animals the unfeeling seed or egg receives no pain, but the animal receives pleasure which consumes it. Under this article may be included the bodies of animals which die naturally. 3. But the last method of supporting animal bodies by the destruction of other living animals, as lions preying upon lambs, these upon living vegetables, and mankind upon them all, would appear to be a less perfect part of the economy of nature than those before mentioned, as contributing less to the sum of general happiness.]

"Now his hard hands on Mona's rifted crest, 280 Bosom'd in rock, her azure ores arrest; With iron lips his rapid rollers seize The lengthening bars, in thin expansion squeeze; Descending screws with ponderous fly-wheels wound The tawny plates, the new medallions round; 285 Hard dyes of steel the cupreous circles cramp, And with quick fall his ma.s.sy hammers stamp.

The Harp, the Lily and the Lion join, And GEORGE and BRITAIN guard the sterling coin.

[_Mona's rifted crest_. l. 279. Alluding to the very valuable copper- mines in the isle of Anglesey, the property of the Earl of Uxbridge.]

[_With iron-lips_. l. 281. Mr. Boulton has lately constructed at Soho near Birmingham, a most magnificent apparatus for Coining, which has cost him some thousand pounds; the whole machinery is moved by an improved steam-engine, which rolls the copper for half-pence finer than copper has before been rolled for the purpose of making money; it works the coupoirs or screw-presses for cutting out the circular pieces of copper; and coins both the faces and edges of the money at the same time, with such superior excellence and cheapness of workmanship, as well as with marks of such powerful machinery as must totally prevent clandestine imitation, and in consequence save many lives from the hand of the executioner; a circ.u.mstance worthy the attention of a great minister. If a civic crown was given in Rome for preserving the life of one citizen, Mr. Boulton should be covered with garlands of oak! By this machinery four boys of ten or twelve years old are capable of striking thirty thousand guineas in an hour, and the machine itself keeps an unerring account of the pieces struck.]

"Soon shall thy arm, UNCONQUER'D STEAM! afar 290 Drag the slow barge, or drive the rapid car; Or on wide-waving wings expanded bear The flying-chariot through the fields of air.

--Fair crews triumphant, leaning from above, Shall wave their fluttering kerchiefs as they move; 295 Or warrior-bands alarm the gaping crowd, And armies shrink beneath the shadowy cloud.

"So mighty HERCULES o'er many a clime Waved his vast mace in Virtue's cause sublime, Unmeasured strength with early art combined, 300 Awed, served, protected, and amazed mankind.-- First two dread Snakes at JUNO'S vengeful nod Climb'd round the cradle of the sleeping G.o.d; Waked by the shrilling hiss, and rustling sound, And shrieks of fair attendants trembling round, 305 Their gasping throats with clenching hands he holds; And Death untwists their convoluted folds.

Next in red torrents from her sevenfold heads Fell HYDRA'S blood on Lerna's lake he sheds; Grasps ACHELOUS with resistless force, 310 And drags the roaring River to his course; Binds with loud bellowing and with hideous yell The monster Bull, and threefold Dog of h.e.l.l.

[_So mighty Hercules_. l. 297. The story of Hercules seems of great antiquity, as appears from the simplicity of his dress and armour, a lion's skin and a club; and from the nature of many of his exploits, the destruction of wild beasts and robbers. This part of the history of Hercules seems to have related to times before the invention of the bow and arrow, or of spinning flax. Other stories of Hercules are perhaps of later date, and appear to be allegorical, as his conquering the river- G.o.d Achilous, and bringing Cerberus up to day light; the former might refer to his turning the course of a river, and draining a mora.s.s, and the latter to his exposing a part of the superst.i.tion of the times. The strangling the lion and tearing his jaws asunder, are described from a statue in the Museum Florentinum, and from an antique gem; and the grasping Anteus to death in his arms as he lifts him from the earth, is described from another antient cameo. The famous pillars of Hercules have been variously explained. Pliny a.s.serts that the natives of Spain and of Africa believed that the mountains of Abyla and Calpe on each side of the straits of Gibraltar were the pillars of Hercules; and that they were reared by the hands of that G.o.d, and the sea admitted between them. Plin. Hist. Nat. p. 46. Edit. Manut. Venet. 1609.

If the pa.s.sage between the two continents was opened by an earthquake in antient times, as this allegorical story would seem to countenance, there must have been an immense current of water at first run into the Mediterranean from the Atlantic; since there is at present a strong stream sets always from thence into the Mediterranean. Whatever may be the cause, which now constantly operates, so as to make the surface of the Mediterranean lower than that of the Atlantic, it must have kept it very much lower before a pa.s.sage for the water through the streights was opened. It is probable before such an event took place, the coasts and islands of the Mediterranean extended much further into that sea, and were then for a great extent of country, destroyed by the floods occasioned by the new rise of water, and have since remained beneath the sea. Might not this give rise to the flood of Deucalion? See note Ca.s.sia, V. II. of this work.]

"Then, where Nemea's howling forests wave, He drives the Lion to his dusky cave; 315 Seized by the throat the growling fiend disarms, And tears his gaping jaws with sinewy arms; Lifts proud ANTEUS from his mother-plains, And with strong grasp the struggling Giant strains; Back falls his fainting head, and clammy hair, 320 Writhe his weak limbs, and flits his life in air;-- By steps reverted o'er the blood-dropp'd fen He tracks huge CACUS to his murderous den; Where breathing flames through brazen lips he fled, And shakes the rock-roof'd cavern o'er his head.

325 "Last with wide arms the solid earth He tears, Piles rock on rock, on mountain mountain rears; Heaves up huge ABYLA on Afric's sand, Crowns with high CALPe Europe's saliant strand, Crests with opposing towers the splendid scene, 330 And pours from urns immense the sea between.-- --Loud o'er her whirling flood Charybdis roars, Affrighted Scylla bellows round his sh.o.r.es, Vesuvio groans through all his echoing caves, And Etna thunders o'er the insurgent waves.

335 VII. 1. NYMPHS! YOUR fine hands ethereal floods ama.s.s From the warm cushion, and the whirling gla.s.s; Beard the bright cylinder with golden wire, And circ.u.mfuse the gravitating fire.

Cold from each point cerulean l.u.s.tres gleam, 340 Or shoot in air the scintillating stream.

So, borne on brazen talons, watch'd of old The sleepless dragon o'er his fruits of gold; Bright beam'd his scales, his eye-b.a.l.l.s blazed with ire, And his wide nostrils breath'd inchanted fire.

[_Ethereal floods ama.s.s_. l. 335. The theory of the acc.u.mulation of the electric fluid by means of the gla.s.s-globe and cushion is difficult to comprehend. Dr. Franklin's idea of the pores of the gla.s.s being opened by the friction, and thence rendered capable of attracting more electric fluid, which it again parts with, as the pores contract again, seems a.n.a.logous in some measure to the heat produced by the vibration, or condensation of bodies, as when a nail is hammered or filed till it becomes hot, as mentioned in additional Notes, No. VII. Some philosophers have endeavoured to account for this phenomenon by supposing the existence of two electric fluids which may be called the vitreous and resinous ones, instead of the plus and minus of the same ether. But its acc.u.mulation on the rubbed gla.s.s bears great a.n.a.logy to its acc.u.mulation on the surface of the Leyden bottle, and can not perhaps be explained from any known mechanical or chemical principle.

See note on Gymnotus. l. 202, of this Canto.]