The Botanic Garden Volume I Part 34

The rays refracted by the convexity of the atmosphere; the particles of air and of water are blue; shadow by means of a candle in the day; halo round the moon in a fog; bright spot in the cornea of the eye; light from cat's eyes in the dark, from a horse's eyes in a cavern, coloured by the choroid coat within the eye.

NOTE IV ... COMETS.

Tails of comets from rarified vapour, like northern lights, from electricity; twenty millions of miles long; expected comet.

NOTE V ... SUN'S RAYS.

Dispute about phlogiston; the sun the fountain from whence all phlogiston is derived; its rays not luminous till they arrive at our atmosphere; light owing to their combustion with air, whence an unknown acid; the sun is on fire only on its surface; the dark spots on it are excavations through its luminous crust.

NOTE VI ... CENTRAL FIRES.

Sun's heat much less than that from the fire at the earth's centre; sun's heat penetrates but a few feet in summer; some mines are warm; warm springs owing to subterraneous fire; situations of volcanos on high mountains; original nucleus of the earth; deep vallies of the ocean; distant perception of earthquakes; great attraction of mountains; variation of the compa.s.s; countenance the existence of a cavity or fluid lava within the earth.

NOTE VII ... ELEMENTARY HEAT.

Combined and sensible heat; chemical combinations attract heat, solutions reject heat; ice cools boiling water six times as much as cold water cools it; cold produced by evaporation; heat by devaporation; capacities of bodies in respect to heat, 1. Existence of the matter of heat shewn from the mechanical condensation and rarefaction of air, from the steam produced in exhausting a receiver, snow from rarefied air, cold from discharging an air-gun, heat from vibration or friction; 2.

Matter of heat a.n.a.logous to the electric fluid in many circ.u.mstances, explains many chemical phenomena.

NOTE VIII ... MEMNON'S LYRE.

Mechanical impulse of light dubious; a gla.s.s tube laid horizontally before a fire revolves; pulse-gla.s.s suspended on a centre; black leather contracts in the suns.h.i.+ne; Memnon's statue broken by Cambyses.

NOTE IX ... LUMINOUS INSECTS.

Eighteen species of glow-worm, their light owing to their respiration in transparent lungs; Acudia of Surinam gives light enough to read and draw by, use of its light to the insect; luminous sea-insects adhere to the skin of those who bathe in the ports of Languedoc, the light may arise from putrescent slime.

NOTE X ... PHOSPHORUS.

Discovered by Kunkel, Brandt, and Boyle; produced in respiration, and by luminous insects, decayed wood, and calcined sh.e.l.ls; bleaching a slow combustion in which the water is decomposed; rancidity of animal fat owing to the decomposition of water on its surface; aerated marine acid does not whiten or bleach the hand.

NOTE XI ... STEAM-ENGINE.

Hero of Alexandria first applied steam to machinery, next a French writer in 1630, the Marquis of Worcester in 1655, Capt. Savery in 1689, Newcomen and Cawley added the piston; the improvements of Watt and Boulton; power of one of their large engines equal to two hundred horses.

NOTE XII ... FROST.

Expansion of water in freezing; injury done by vernal frosts; fish, eggs, seeds, resist congelation; animals do not resist the increase of heat; frosts do not meliorate the ground, nor are in general salubrious; damp air produces cold on the skin by evaporation; snow less pernicious to agriculture than heavy rains for two reasons.

NOTE XIII ... ELECTRICITY.

1. _Points_ preferable to k.n.o.bs for defence of buildings; why points emit the electric fluid; diffusion of oil on water; mountains are points on the earth's globe; do they produce ascending currents of air? 2.

_Fairy-rings_ explained; advantage of paring and burning ground.

NOTE XIV ... BUDS AND BULBS.

A tree is a swarm of individual plants; vegetables are either oviparous or viviparous; are all annual productions like many kinds of insects?

Hybernacula, a new bark annually produced over the old one in trees and in some herbaceous plants, whence their roots seem end-bitten; all bulbous roots perish annually; experiment on a tulip-root; both the leaf-bulbs and the flower-bulbs are annually renewed.

NOTE XV ... SOLAR VOLCANOS.

The spots in the sun are cavities, some of them four thousand miles deep and many times as broad; internal parts of the sun are not in a state of combustion; volcanos visible in the sun; all the planets together are less than one six hundred and fiftieth part of the sun; planets were ejected from the sun by volcanos; many reasons shewing the probability of this hypothesis; Mr. Buffon's hypothesis that planets were struck off from the sun by comets; why no new planets are ejected from the sun; some comets and the georgium sidus may be of later date; Sun's matter decreased; Mr. Ludlam's opinion, that it is possible the moon might be projected from the earth.

NOTE XVI ... CALCAREOUS EARTH.

High mountains and deep mines replete with sh.e.l.ls; the earth's nucleus covered with limestone; animals convert water into limestone; all the calcareous earth in the world formed in animal and vegetable bodies; solid parts of the earth increase; the water decreases; tops of calcareous mountains dissolved; whence spar, marbles, chalk, stalact.i.tes; whence alabaster, fluor, flint, granulated limestone, from solution of their angles, and by attrition; tupha deposited on moss; limestones from sh.e.l.ls with animals in them; liver-stone from fresh- water muscles; calcareous earth from land-animals and vegetables, as marl; beds of marble softened by fire; whence Bath-stone contains lime as well as limestone.

NOTE XVII ... MORa.s.sES.

The production of mora.s.ses from fallen woods; account by the Earl Cromartie of a new mora.s.s; mora.s.ses lose their salts by solution in water; then their iron; their vegetable acid is converted into marine, nitrous, and vitriolic acids; whence gypsum, alum, sulphur; into fluor- acid, whence fluor; into siliceous acid, whence flint, the sand of the sea, and other strata of siliceous sand and marl; some mora.s.ses ferment like new hay, and, subliming their phlogistic part, form coal-beds above and clay below, which are also produced by elutriation; sh.e.l.l-fish in some mora.s.ses, hence sh.e.l.ls sometimes found on coals and over iron- stone.

NOTE XVIII ... IRON

Calciform ores; combustion of iron in vital air; steel from deprivation of vital air; welding; hardness; brittleness like Rupert's drops; specific levity; hardness and brittleness compared; steel tempered by its colours; modern production of iron, manganese, calamy; septaria of iron-stone ejected from volcanos; red-hot cannon b.a.l.l.s.

NOTE XIX ... FLINT.

1. _Siliceous rocks_ from mora.s.ses; their cements. 2. _Siliceous trees_; coloured by iron or manganese; Peak-diamonds; Bristol-stones; flint in form of calcareous spar; has been fluid without much heat; obtained from powdered quartz and fluor-acid by Bergman and by Achard. 3. _Agates and onyxes_ found in sand-rocks; of vegetable origin; have been in complete fusion; their concentric coloured circles not from superinduction but from congelation; experiment of freezing a solution of blue vitriol; iron and manganese repelled in spheres as the nodule of flint cooled; circular stains of marl in salt-mines; some flint nodules resemble knots of wood or roots. 4. _Sand of the sea_; its acid from mora.s.ses; its base from sh.e.l.ls. 5. _Chert or petrosilex_ stratified in cooling; their colour and their acid from sea-animals; labradore-stone from mother- pearl. 6. _Flints in chalk-beds_; their form, colour, and acid, from the flesh of sea-animals; some are hollow and lined with crystals; contain iron; not produced by injection from without; coralloids converted to flint; French-millstones; flints sometimes found in solid strata. 7.

_Angles of sand_ destroyed by attrition and solution in steam; siliceous breccia cemented by solution in red-hot water. 8. _Basaltes and granites_ are antient lavas; basaltes raised by its congelation not by subterraneous fire.

NOTE XX ... CLAY.

Fire and water two great agents; stratification from precipitation; many stratified materials not soluble in water. 1. Stratification of lava from successive acc.u.mulation. 2. Stratifications of limestone from the different periods of time in which the sh.e.l.ls were deposited. 3.

Stratifications of coal, and clay, and sandstone, and iron-ores, not from currents of water, but from the production of mora.s.s-beds at different periods of time; mora.s.s-beds become ignited; their bitumen and sulphur is sublimed; the clay, lime, and iron remain; whence sand, marle, coal, white clay in valleys, and gravel-beds, and some ochres, and some calcareous depositions owing to alluviation; clay from decomposed granite; from the lava of Vesuvius; from vitreous lavas.

NOTE XXI ... ENAMELS.

Rose-colour and purple from gold; precipitates of gold by alcaline salt preferable to those by tin; aurum fulminans long ground; tender colours from gold or iron not dissolved but suspended in the gla.s.s; cobalts; calces of cobalt and copper require a strong fire; Ka-o-lin and Pe-tun-tse the same as our own materials.

NOTE XXII ... PORTLAND VASE.