4. SAND OF THE SEA.

The great abundance of siliceous sand at the bottom of the ocean may in

part be washed down from the siliceous rocks above described, but in

general I suppose it derives its acid only from the vegetable and animal

matter of morasses, which is carried down by floods or by the

atmosphere, and becomes united in the sea with its calcareous base from

shells and coralloids, and thus assumes its crystalline form at the

bottom of the ocean, and is there intermixed with gravel or other

matters washed from the mountains in its vicinity.

5. CHERT, OR PETROSILEX.

The rocks of marble are often alternately intermixed with strata of

chert, or coarse flint, and this in beds from one to three feet thick,

as at Ham and Matlock, or of less than the tenth of an inch in

thickness, as a mile or two from Bakewell in the road to Buxton. It is

difficult to conceive in what manner ten or twenty strata of either

limestone or flint, of different shades of white and black, could be

laid quite regularly over each other from sediments or precipitations

from the sea; it appears to me much easier to comprehend, by supposing

with Dr. Hutton, that both the solid rocks of marble and the flint had

been fused by great heat, (or by heat and water,) under immense

pressure; by its cooling or congealing the colouring matter might be

detruded, and form parallel or curvilinean strata, as above explained.

The colouring matter both of limestone and flint was probably owing to

the flesh of peculiar animals, as well as the siliceous acid, which

converted some of the limestone into flint; or to some strata of shell-

fish having been overwhelmed when alive with new materials, while others

dying in their natural situations would lose their fleshy parts, either

by its putrid solution in the water or by its being eaten by other sea-

insects. I have some calcareous fossil shells which contain a black

coaly matter in them, which was evidently the body of the animal, and

others of the same kind filled with spar instead of it. The Labradore

stone has I suppose its colours from the nacre or mother-pearl shells,

from which it was probably produced. And there is a stratum of

calcareous matter about six or eight inches thick at Wingerworth in

Derbyshire over the iron-beds, which is replete with shells of fresh-

water muscles, and evidently obtains its dark colour from them, as

mentioned in note XVI. Many nodules of flint resemble in colour as well

as in form the shell of the echinus or sea-urchin; others resemble some

coralloids both in form and colour; and M. Arduini found in the Monte de

Pancrasio, red flints branching like corals, from whence they seem to

have obtained both their form and their colour. Ferber's Travels in

Italy, p. 42.

6. NODULES OF FLINT IN CHALK-BEDS.

As the nodules of flint found in chalk-beds possess no marks of having

been rounded by attrition or solution, I conclude that they have gained

their form as well as their dark colour from the flesh of the shell-fish

from which they had their origin; but which have been so compleatly

fused by heat, or heat and water, as to obliterate all vestiges of the

shell, in the same manner as the nodules of agate and onyx were produced

from parts of vegetables, but which had been so completely fused as to

obliterate all marks of their organization, or as many iron-nodules have

obtained their form and origin from peculiar vegetables.

Some nodules in chalk-beds consist of shells of echini filled up with

chalk, the animal having been dissolved away by putrescence in water, or

eaten by other sea-insects; other shells of echini, in which I suppose

the animal's body remained, are converted into flint but still retain

the form of the shell. Others, I suppose as above, being more completely

fused, have become flint coloured by the animal flesh, but without the

exact form either of the flesh or shell of the animal. Many of these are

hollow within and lined with crystals, like the Scot's-pebbles above

described; but as the colouring matter of animal bodies differs but

little from each other compared with those of vegetables, these flints

vary less in their colours than those above mentioned. At the same time

as they cooled in concentric spheres like the Scot's-pebbles, they often

possess faint rings of colours, and always break in conchoide forms

like them.

This idea of the production of nodules of flint in chalk-beds is

countenanced from the iron which generally appears as these flints

become decomposed by the air; which by uniting with the iron in their

composition reduces it from a vitrescent state to that of calx, and thus

renders it visible. And secondly, by there being no appearance in chalk-

beds of a string or pipe of siliceous matter connecting one nodule with

another, which must have happened if the siliceous matter, or its acid,

had been injected from without according to the idea of Dr. Hutton. And

thirdly, because many of them have very large cavities at their centres,

which should not have happened had they been formed by the injection of

a material from without.

When shells or chalk are thus converted from calcareous to siliceous

matter by the flesh of the animal, the new flint being heavier than the

shell or chalk occupies less space than the materials it was produced

from; this is the cause of frequent cavities within them, where the

whole mass has not been completely fused and pressed together. In

Derbyshire there are masses of coralloid and other shells which have

become siliceous, and are thus left with large vacuities sometimes

within and sometimes on the outside of the remaining form of the shell,

like the French millstones, and I suppose might serve the same purpose;

the gravel of the Derwent is full of specimens of this kind.

Since writing the above I have received a very ingenious account of

chalk-beds from Dr. MENISH of Chelmsford. He distinguishes chalk-beds

into three kinds; such as have been raised from the sea with little

disturbance of their strata, as the cliffs of Dover and Margate, which

he terms _intire_ chalk. Another state of chalk is where it has suffered

much derangement, as the banks of the Thames at Gravesend and Dartford.

And a third state where fragments of chalk have been rounded by water,

which he terms _alluvial_ chalk. In the first of these situations of

chalk he observes, that the flint lies in strata horizontally, generally

in distinct nodules, but that he has observed two instances of solid

plates or strata of flint, from an inch to two inches in thickness,

interposed between the chalk-beds; one of these is in a chalk-bank by

the road side at Berkhamstead, the other in a bank on the road from

Chatham leading to Canterbury. Dr. Menish has further observed, that

many of the echini are crushed in their form, and yet filled with flint,

which has taken the form of the crushed shell, and that though many

flint nodules are hollow, yet that in some echini the siliceum seems to

have enlarged, as it passed from a fluid to a solid state, as it swells

out in a protuberance at the mouth and anus of the shell, and that

though these shells are so filled with flint yet that in many places the

shell itself remains calcareous. These strata of nodules and plates of

flint seem to countenance their origin from the flesh of a stratum of

animals which perished by some natural violence, and were buried in

their shells.

7. ANGLES OF SILICEOUS SAND.

In many rocks of siliceous sand the particles retain their angular form,

and in some beds of loose sand, of which there is one of considerable

purity a few yards beneath the marl at Normington about a mile south of

Derby. Other siliceous sands have had their angles rounded off, like the

pebbles in gravel-beds. These seem to owe their globular form to two

causes; one to their attrition against each other, when they may for

centuries have lain at the bottom of the sea, or of rivers; where they

may have been progressively accumulated, and thus progressively at the

same time rubbed upon each other by the dashing of the water, and where

they would be more easily rolled over each other by their gravity being

so much less than in air. This is evidently now going on in the river

Derwent, for though there are no limestone rocks for ten or fifteen

miles above Derby, yet a great part of the river-gravel at Derby

consists of limestone nodules, whose angles are quite worn off in their

descent down the stream.

There is however another cause which must have contributed to round the

angles both of calcareous and siliceous fragments; and that is, their

solubility in water; calcareous earth is perpetually found suspended in

the waters which pass over it; and the earth of flints was observed by

Bergman to be contained in water in the proportion of one grain to a

gallon. Kirwan's Mineralogy, p. 107. In boiling water, however, it is

soluble in much greater proportion, as appears from the siliceous earth

sublimed in the distillation of fluor acid in glass vessels; and from

the basons of calcedony which surrounded the jets of hot water near

mount Heccla in Iceland. Troil on Iceland. It is probable most siliceous

sands or pebbles have at some ages of the world been long exposed to

aqueous steams raised by subterranean fires. And if fragments of stone

were long immersed in a fluid menstrum, their angular parts would be

first dissolved, on account of their greater surface.

Many beds of siliceous gravel are cemented together by a siliceous

cement, and are called breccia; as the plumb-pudding stones of

Hartfordshire, and the walls of a subterraneous temple excavated by Mr.

Curzon, at Hagley near Rugely in Staffordfshire; these may have been

exposed to great heat as they were immersed in water; which water under

great pressure of superincumbent materials may have been rendered red-

hot, as in Papin's digester; and have thus possessed powers of solution

with which we are unacquainted.

8. BASALTES AND GRANITES.

Another source of siliceous stones is from the granite, or basaltes, or

porphyries, which are of different hardnesses according to the materials

of their composition, or to the fire they have undergone; such are the

stones of Arthur's-hill near Edinburgh, of the Giant's Causway in

Ireland, and of Charnwood Forest in Leicestershire; the uppermost

stratum of which last seems to have been cracked either by its

elevation, or by its hastily cooling after ignition by the contact of

dews or snows, and thus breaks into angular fragments, such as the

streets of London are paved with; or have had their angles rounded by

attrition or by partial solution; and have thus formed the common paving

stones or bowlers; as well as the gravel, which is often rolled into

strata amid the siliceous sand-beds, which are either formed or

collected in the sea.

In what manner such a mass of crystallized matter as the Giant's Causway

and similar columns of basaltes, could have been raised without other

volcanic appearances, may be a matter not easy to comprehend; but there

is another power in nature besides that of expansile vapour which may

have raised some materials which have previously been in igneous or

aqueous solution; and that is the act of congelation. When the water in

the experiments above related of Major Williams had by congelation

thrown out the plugs from the bomb-shells, a column of ice rose from the

hole of the bomb six or eight inches high. Other bodies I suspect

increase in bulk which crystallize in cooling, as iron and type-metal. I

remember pouring eight or ten pounds of melted brimstone into a pot to

cool and was surprized to see after a little time a part of the fluid

beneath break a hole in the congealed crust above it, and gradually rise

into a promontory several inches high; the basaltes has many marks of

fusion and of crystallization and may thence, as well as many other

kinds of rocks, as of spar, marble, petrosilex, jasper, &c. have been

raised by the power of congelation, a power whose quantity has not yet

been ascertained, and perhaps greater and more universal than that of

vapours expanded by heat. These basaltic columns rise sometimes out of

mountains of granite itself, as mentioned by Dr. Beddoes, (Phil.

Transact. Vol. LXXX.) and as they seem to consist of similar materials

more completely fused, there is still greater reason to believe them to

have been elevated in the cooling or crystallization of the mass. See

note XXIV.

NOTE XX.--CLAY.

_Whence ductile Clays in wide expansion spread,

Soft as the Cygnet's down, their snow-white bed._

CANTO II. l. 277.

The philosophers, who have attended to the formation of the earth, have

acknowledged two great agents in producing the various changes which the

terraqueous globe has undergone, and these are water and fire. Some of

them have perhaps ascribed too much to one of these great agents of

nature, and some to the other. They have generally agreed that the

stratification of materials could only be produced from sediments or

precipitations, which were previously mixed or dissolved in the sea; and

that whatever effects were produced by fire were performed afterwards.

There is however great difficulty in accounting for the universal

stratification of the solid globe of the earth in this manner, since

many of the materials, which appear in strata, could not have been

suspended in water; as the nodules of flint in chalk-beds, the extensive

beds of shells, and lastly the strata of coal, clay, sand, and iron-ore,

which in most coal-countries lie from five to seven times alternately

stratified over each other, and none of them are soluble in water. Add

to this if a solution of them or a mixture of them in water could be

supposed, the cause of that solution must cease before a precipitation

could commence.

1. The great masses of lava, under the various names of granite,

porphyry, toadstone, moor-stone, rag, and slate, which constitute the

old world, may have acquired the stratification, which some of them

appear to possess, by their having been formed by successive eruptions

of a fluid mass, which at different periods of antient time arose from

volcanic shafts and covered each other, the surface of the interior mass

of lava would cool and become solid before the superincumbent stratum

was poured over it; to the same cause may be ascribed their different

compositions and textures, which are scarcely the same in any two parts

of the world.

2. The stratifications of the great masses of limestone, which were

produced from sea-shells, seem to have been formed by the different

times at which the innumerable shells were produced and deposited. A

colony of echini, or madrepores, or cornua ammonis, lived and perished

in one period of time; in another a new colony of either similar or

different shells lived and died over the former ones, producing a

stratum of more recent shell over a stratum of others which had began to

petrify or to become marble; and thus from unknown depths to what are

now the summits of mountains the limestone is disposed in strata of

varying solidity and colour. These have afterwards undergone variety of

changes by their solution and deposition from the water in which they

were immersed, or from having been exposed to great heat under great

pressure, according to the ingenious theory of Dr. Hutton. Edinb.

Transact. Vol. I. See Note XVI.

3. In most of the coal-countries of this island there are from five to

seven beds of coal stratified with an equal number of beds, though of

much greater thickness, of clay and sandstone, and occasionally of iron-

ores. In what manner to account for the stratification of these

materials seems to be a problem of greater difficulty. Philosophers have

generally supposed that they have been arranged by the currents of the

sea; but considering their insolubility in water, and their almost

similar specific gravity, an accumulation of them in such distinct beds

from this cause is altogether inconceiveable, though some coal-countries

bear marks of having been at some time immersed beneath the waves and

raised again by subterranean fires.

The higher and lower parts of morasses were necessarily produced at

different periods of time, see Note XVII. and would thus originally be

formed in strata of different ages. For when an old wood perished, and

produced a morass, many centuries would elapse before another wood could

grow and perish again upon the same ground, which would thus produce a

new stratum of morass over the other, differing indeed principally in

its age, and perhaps, as the timber might be different, in the

proportions of its component parts.

Now if we suppose the lowermost stratum of a morass become ignited, like

fermenting hay, (after whatever could be carried away by solution in

water was gone,) what would happen? Certainly the inflammable part, the

oil, sulphur, or bitumen, would burn away, and be evaporated in air; and

the fixed parts would be left, as clay, lime, and iron; while some of

the calcareous earth would join with the siliceous acid, and produce

sand, or with the argillaceous earth, and produce marl. Thence after

many centuries another bed would take fire, but with less degree of

ignition, and with a greater body of morass over it, what then would

happen? The bitumen and sulphur would rise and might become condensed

under an impervious stratum, which might not be ignited, and there form

coal of different purities according to its degree of fluidity, which

would permit some of the clay to subside through it into the place from

which it was sublimed.

Some centuries afterwards another similar process might take place, and

either thicken the coal-bed, or produce a new clay-bed, or marl, or

sand, or deposit iron upon it, according to the concomitant

circumstances above mentioned.

I do not mean to contend that a few masses of some materials may not

have been rolled together by currents, when the mountains were much more

elevated than at present, and in consequence the rivers broader and more

rapid, and the storms of rain and wind greater both in quantity and

force. Some gravel-beds may have been thus washed from the mountains;

and some white clay washed from morasses into valleys beneath them; and

some ochres of iron dissolved and again deposited by water; and some

calcareous depositions from water, (as the bank for instance on which

stand the houses at Matlock-bath;) but these are of small extent or

consequence compared to the primitive rocks of granite or porpyhry which

form the nucleus of the earth, or to the immense strata of limestone

which crust over the greatest part of this granite or porphyry; or

lastly to the very extensive beds of clay, marl, sandstone, coal, and

iron, which were probably for many millions of years the only parts of

our continents and islands, which were then elevated above the level of

the sea, and which on that account became covered with vegetation, and

thence acquired their later or superincumbent strata, which constitute,

what some have termed, the new world.

There is another source of clay, and that of the finest kind, from

decomposed granite, this is of a snowy white and mixed with mining

particles of mica, of this kind is an earth from the country of

Cherokees. Other kinds are from less pure lavas; Mr. Ferber asserts that

the sulphurous steams from Mount Vesuvius convert the lava into clay.

"The lavas of the antient Solfatara volcano have been undoubtedly of a

vitreous nature, and these appear at present argillaceous. Some

fragments of this lava are but half or at one side changed into clay,

which either is viscid or ductile, or hard and stoney. Clays by fire are

deprived of their coherent quality, which cannot be restored to them by

pulverization, nor by humectation. But the sulphureous Solfatara steams

restore it, as may be easily observed on the broken pots wherein they

gather the sal ammoniac; though very well baked and burnt at Naples they

are mollified again by the acid steams into a viscid clay which keeps

the former fire-burnt colour." Travels in Italy, p. 156.

NOTE XXI.--ENAMELS.

_Smear'd her huge dragons with metallic hues,

With golden purples, and cobaltic blues;_

CANTO II. l. 287.

The fine bright purples or rose colours which we see on china cups are

not producible with any other material except gold, manganese indeed

gives a purple but of a very different kind.

In Europe the application of gold to these purposes appears to be of

modern invention. Cassius's discovery of the precipitate of gold by tin,

and the use of that precipitate for colouring glass and enamels, are now

generally known, but though the precipitate with tin be more successful

in producing the ruby glass, or the colourless glass which becomes red

by subsequent ignition, the tin probably contributing to prevent the

gold from separating, (which it is very liable to do during the fusion;

yet, for enamels, the precipitates made by alcaline salts answer equally

well, and give a finer red, the colour produced by the tin precipitate

being a bluish purple, but with the others a rose red. I am informed

that some of our best artists prefer aurum fulminans, mixing it, before

it has become dry, with the white composition or enamel flux; when once

it is divided by the other matter, it is ground with great safety, and

without the least danger of explosion, whether moist or dry. The colour

is remarkably improved and brought forth by long grinding, which

accordingly makes an essential circumstance in the process.

The precipitates of gold, and the colcothar or other red preparations of

iron, are called _tender_ colours. The heat must be no greater than is

just sufficient to make the enamel run upon the piece, for if greater,

the colours will be destroyed or changed to a different kind. When the

vitreous matter has just become fluid it seems as if the coloured

metallic calx remained barely _intermixed_ with it, like a coloured

powder of exquisite tenuity suspended in water: but by stronger fire the

calx is _dissolved_, and metallic colours are altered by _solution_ in

glass as well as in acids or alcalies.

The Saxon mines have till very lately almost exclusively supplied the

rest of Europe with cobalt, or rather with its preparations, zaffre and

smalt, for the exportation of the ore itself is there a capital crime.

Hungary, Spain, Sweden, and some other parts of the continent, are now

said to afford cobalts equal to the Saxon, and specimens have been

discovered in our own island, both in Cornwall and in Scotland; but

hitherto in no great quantity.

Calces of cobalt and of copper differ very materially from those above

mentioned in their application for colouring enamels. In those the calx

has previously acquired the intended colour, a colour which bears a red

heat without injury, and all that remains is to fix it on the piece by a

vitreous flux. But the blue colour of cobalt, and the green or bluish

green of copper, are _produced_ by vitrification, that is, by _solution_

in the glass, and a strong fire is necessary for their perfection. These

calces therefore, when mixed with the enamel flux, are melted in

crucibles, once or oftener, and the deep coloured opake glass, thence

resulting, is ground into unpalpable powder, and used for enamel. One

part of either of these calces is put to ten, sixteen, or twenty parts

of the flux, according to the depth of colour required. The heat of the

enamel kiln is only a full red, such as is marked on Mr. Wedgwood's

thermometer 6 degrees. It is therefore necessary that the flux be so

adjusted as to melt in that low heat. The usual materials are flint, or

flint-glass, with a due proportion of red-led, or borax, or both, and

sometimes a little tin calx to give opacity.

_Ka-o-lin_ is the name given by the Chinese to their porcelain clay, and

_pe-tun-tse_ to the other ingredient in their China ware. Specimens of

both these have been brought into England, and found to agree in quality

with some of our own materials. Kaolin is the very same with the clay

called in Cornwall [Transcriber's note: word missing] and the petuntse

is a granite similar to the Cornish moorstone. There are differences,

both in the Chinese petuntses, and the English moorstones; all of them

contain micaceous and quartzy particles, in greater or less quantity,

along with feltspat, which last is the essential ingredient for the

porcelain manufactory. The only injurious material commonly found in

them is iron, which discolours the ware in proportion to its quantity,

and which our moorstones are perhaps more frequently tainted with than

the Chinese. Very fine porcelain has been made from English materials

but the nature of the manufacture renders the process precarious and the

profit hazardous; for the semivitrification, which constitutes

porcelain, is necessarily accompanied with a degree of softness, or

semifusion, so that the vessels are liable to have their forms altered

in the kiln, or to run together with any accidental augmentations of the

fire.

NOTE XXII.--PORTLAND VASE.

_Or bid Mortality rejoice or mourn

O'er the fine forms of Portland's mystic urn._

CANTO II. l. 319.

The celebrated funereal vase, long in possession of the Barberini

family, and lately purchased by the Duke of Portland for a thousand

guineas, is about ten inches high and six in diameter in the broadest

part. The figures are of most exquisite workmanship in bas relief of

white opake glass, raised on a ground of deep blue glass, which appears

black except when held against the light. Mr. Wedgwood is of opinion

from many circumstances that the figures have been made by cutting away

the external crust of white opake glass, in the manner the finest

cameo's have been produced, and that it must thence have been the labour

of a great many years. Some antiquarians have placed the time of its

production many centuries before the christian aera; as sculpture was

said to have been declining in respect to its excellence in the time of

Alexander the Great. See an account of the Barberini or Portland vase by

M. D'Hancarville, and by Mr. Wedgwood.

Many opinions and conjectures have been published concerning the figures

on this celebrated vase. Having carefully examined one of Mr. Wedgwood's

beautiful copies of this wonderful production of art, I shall add one

more conjecture to the number.

Mr. Wedgwood has well observed that it does not seem probable that the

Portland vase was purposely made for the ashes of any particular person

deceased, because many years must have been necessary for its

production. Hence it may be concluded, that the subject of its

embellishments is not private history but of a general nature. This

subject appears to me to be well chosen, and the story to be finely

told; and that it represents what in antient times engaged the attention

of philosophers, poets, and heroes, I mean a part of the Eleusinian

mysteries.

These mysteries were invented in Aegypt, and afterwards transferred to

Greece, and flourished more particularly at Athens, which was at the

same time the seat of the fine arts. They consisted of scenical

exhibitions representing and inculcating the expectation of a future

life after death, and on this account were encouraged by the government,

insomuch that the Athenian laws punished a discovery of their secrets

with death. Dr. Warburton has with great learning and ingenuity shewn

that the descent of Aeneas into hell, described in the Sixth Book of

Virgil, is a poetical account of the representations of the future state

in the Eleusinian mysteries. Divine Legation, Vol. I. p. 210.

And though some writers have differed in opinion from Dr. Warburton on

this subject, because Virgil has introduced some of his own heroes into

the Elysian fields, as Deiphobus, Palinurus, and Dido, in the same

manner as Homer had done before him, yet it is agreed that the received

notions about a future state were exhibited in these mysteries, and as

these poets described those received notions, they may be said, as far

as these religious doctrines were concerned, to have described the

mysteries.

Now as these were emblematic exhibitions they must have been as well

adapted to the purposes of sculpture as of poetry, which indeed does not

seem to have been uncommon, since one compartment of figures in the

sheild of Aeneas represented the regions of Tartarus. Aen. Lib. X. The

procession of torches, which according to M. De St. Croix was exhibited

in these mysteries, is still to be seen in basso relievo, discovered by

Spon and Wheler. Memoires sur le Mysteres par De St. Croix. 1784. And it

is very probable that the beautiful gem representing the marriage of

Cupid and Psyche, as described by Apuleus, was originally descriptive of

another part of the exhibitions in these mysteries, though afterwards it

became a common subject of antient art. See Divine Legat. Vol. I. p.

323. What subject could have been imagined so sublime for the ornaments

of a funereal urn as the mortality of all things and their

resuscitation? Where could the designer be supplied with emblems for

this purpose, before the Christian era, but from the Eleusinian

mysteries?

1. The exhibitions of the mysteries were of two kinds, those which the

people were permitted to see, and those which were only shewn to the

initiated. Concerning the latter, Aristides calls them "the most

shocking and most ravishing representations." And Stoboeus asserts that

the initiation into the grand mysteries exactly resembles death. Divine

Legat. Vol. I. p. 280, and p. 272. And Virgil in his entrance to the

shades below, amongst other things of terrible form, mentions death.

Aen. VI. This part of the exhibition seems to be represented in one of

the compartments of the Portland vase.

Three figures of exquisite workmanship are placed by the side of a

ruined column whose capital is fallen off, and lies at their feet with

other disjointed stones, they sit on loose piles of stone beneath a

tree, which has not the leaves of any evergreen of this climate, but may

be supposed to be an elm, which Virgil places near the entrance of the

infernal regions, and adds, that a dream was believed to dwell under

every leaf of it. Aen. VI. l. 281. In the midst of this group reclines a

female figure in a dying attitude, in which extreme languor is

beautifully represented, in her hand is an inverted torch, an antient

emblem of extinguished life, the elbow of the same arm resting on a

stone supports her as she sinks, while the other hand is raised and

thrown over her drooping head, in some measure sustaining it and gives

with great art the idea of fainting lassitude. On the right of her sits

a man, and on the left a woman, both supporting themselves on their

arms, as people are liable to do when they are thinking intensely. They

have their backs towards the dying figure, yet with their faces turned

towards her, as if seriously contemplating her situation, but without

stretching out their hands to assist her.

This central figure then appears to me to be an hieroglyphic or

Eleusinian emblem of MORTAL LIFE, that is, the lethum, or death,

mentioned by Virgil amongst the terrible things exhibited at the

beginning of the mysteries. The inverted torch shews the figure to be

emblematic, if it had been designed to represent a real person in the

act of dying there had been no necessity for the expiring torch, as the

dying figure alone would have been sufficiently intelligible;--it would

have been as absurd as to have put an inverted torch into the hand of a

real person at the time of his expiring. Besides if this figure had

represented a real dying person would not the other figures, or one of

them at least, have stretched out a hand to support her, to have eased

her fall among loose stones, or to have smoothed her pillow? These

circumstances evince that the figure is an emblem, and therefore could

not be a representation of the private history of any particular family

or event.

The man and woman on each side of the dying figure must be considered as

emblems, both from their similarity of situation and dress to the middle

figure, and their being grouped along with it. These I think are

hieroglyphic or Eleusinian emblems of HUMANKIND, with their backs toward

the dying figure of MORTAL LIFE, unwilling to associate with her, yet

turning back their serious and attentive countenances, curious indeed to

behold, yet sorry to contemplate their latter end. These figures bring

strongly to one's mind the Adam and Eve of sacred writ, whom some have

supposed to have been allegorical or hieroglyphic persons of Aegyptian

origin, but of more antient date, amongst whom I think is Dr. Warburton.

According to this opinion Adam and Eve were the names of two

hieroglyphic figures representing the early state of mankind; Abel was

the name of an hieroglyphic figure representing the age of pasturage,

and Cain the name of another hieroglyphic symbol representing the age of

agriculture, at which time the uses of iron were discovered. And as the

people who cultivated the earth and built houses would increase in

numbers much faster by their greater production of food, they would

readily conquer or destroy the people who were sustained by pasturage,

which was typified by Cain slaying Abel.

2. On the other compartment of this celebrated vase is exhibited an

emblem of immortality, the representation of which was well known to

constitute a very principal part of the shews at the Eleusinian

mysteries, as Dr. Warburton has proved by variety of authority. The

habitation of spirits or ghosts after death was supposed by the antients

to be placed beneath the earth, where Pluto reigned, and dispensed

rewards or punishments. Hence the first figure in this group is of the

MANES or GHOST, who having passed through an open portal is descending

into a dusky region, pointing his toe with timid and unsteady step,

feeling as it were his way in the gloom. This portal Aeneas enters,

which is described by Virgil,--patet atri janua ditis, Aen. VI. l. 126;

as well as the easy descent,--facilis descensus Averni. Ib. The darkness

at the entrance to the shades is humorously described by Lucian. Div.

Legat. Vol. I. p. 241. And the horror of the gates of hell was in the

time of Homer become a proverb; Achilles says to Ulysses, "I hate a liar

worse than the gates of hell;" the same expression is used in Isaiah,

ch. xxxviii. v. 10. The MANES or GHOST appears lingering and fearful,

and wishes to drag after him a part of his mortal garment, which however

adheres to the side of the portal through which he has passed. The

beauty of this allegory would have been expressed by Mr. Pope, by "We

feel the ruling passion strong in death."

A little lower down in the group the manes or ghost is received by a

beautiful female, a symbol of IMMORTAL LIFE. This is evinced by her

fondling between her knees a large and playful serpent, which from its

annually renewing its external skin has from great antiquity, even as

early as the fable of Prometheus, been esteemed an emblem of renovated

youth. The story of the serpent acquiring immortal life from the ass of

Prometheus, who carried it on his back, is told in Bacon's Works, Vol.

V. p. 462. Quarto edit. Lond. 1778. For a similar purpose a serpent was

wrapped round the large hieroglyphic egg in the temple of Dioscuri, as

an emblem of the renewal of life from a state of death. Bryant's

Mythology, Vol II. p. 359. sec. edit. On this account also the serpent

was an attendant on Aesculapius, which seems to have been the name of

the hieroglyphic figure of medicine. This serpent shews this figure to

be an emblem, as the torch shewed the central figure of the other

compartment to be an emblem, hence they agreeably correspond, and

explain each other, one representing MORTAL LIFE, and the other IMMORTAL

LIFE.

This emblematic figure of immortal life sits down with her feet towards

the figure of Pluto, but, turning back her face towards the timid ghost,

she stretches forth her hand, and taking hold of his elbow, supports his

tottering steps, as well as encourages him to advance, both which

circumstances are thus with wonderful ingenuity brought to the eye. At

the same time the spirit loosely lays his hand upon her arm, as one

walking in the dark would naturally do for the greater certainty of

following his conductress, while the general part of the symbol of

IMMORTAL LIFE, being turned toward the figure of Pluto, shews that she

is leading the phantom to his realms.

In the Pamphili gardens at Rome, Perseus in assisting Andromeda to

descend from the rock takes hold of her elbow to steady or support her

step, and she lays her hand loosely on his arm as in this figure. Admir.

Roman. Antiq.

The figure of PLUTO can not be mistaken, as is agreed by most of the

writers who have mentioned this vase; his grisley beard, and his having

one foot buried in the earth, denotes the infernal monarch. He is placed

at the lowest part of the group, and resting his chin on his hand, and

his arm upon his knee, receives the stranger-spirit with inquisitive

attention; it was before observed that when people think attentively

they naturally rest their bodies in some easy attitude, that more animal

power may be employed on the thinking faculty. In this group of figures

there is great art shewn in giving an idea of a descending plain, viz.

from earth to Elysium, and yet all the figures are in reality on an

horizontal one. This wonderful deception is produced first by the

descending step of the manes or ghost; secondly, by the arm of the

sitting figure of immortal life being raised up to receive him as he

descends; and lastly, by Pluto having one foot sunk into the earth.

There is yet another figure which is concerned in conducing the manes or

ghost to the realms of Pluto, and this is LOVE. He precedes the

descending spirit on expanded wings, lights him with his torch, and

turning back his beautiful countenance beckons him to advance. The

antient God of love was of much higher dignity than the modern Cupid. He

was the first that came out of the great egg of night, (Hesiod. Theog.

V. CXX. Bryant's Mythol. Vol. II. p. 348.) and is said to possess the

keys of the sky, sea, and earth. As he therefore led the way into this

life, he seems to constitute proper emblem for leading the way to a

future life. See Bacon's works. Vol. I. p. 568. and Vol. III. p. 582.

Quarto edit.

The introduction of love into this part of the mysteries requires a

little further explanation. The Psyche of the Aegyptians was one of

their most favourite emblems, and represented the soul, or a future

life; it was originally no other than the aurelia, or butterfly, but in

after times was represented by a lovely female child with the beautiful

wings of that insect. The aurelia, after its first stage as an eruca or

caterpillar, lies for a season in a manner dead, and is inclosed in a

sort of coffin, in this state of darkness it remains all the winter, but

at the return of spring it bursts its bonds and comes out with new life,

and in the most beautiful attire. The Aegyptians thought this a very

proper picture of the soul of man, and of the immortality to which it

aspired. But as this was all owing to divine Love, of which EROS was an

emblem, we find this person frequently introduced as a concomitant of

the soul in general or Psyche. (Bryant's Mythol. Vol. II. p. 386.) EROS,

or divine Love, is for the same reason a proper attendant on the manes

or soul after death, and much contributes to tell the story, that is, to

shew that a soul or manes is designed by the descending figure. From

this figure of Love M. D'Hancarville imagines that Orpheus and Eurydice

are typified under the figure of the manes and immortal life as above

described. It may be sufficient to answer, first, that Orpheus is always

represented with a lyre, of which there are prints of four different

gems in Spence's Polymetis, and Virgil so describes him, Aen. VI.

cytharâ fretus. And secondly, that it is absurd to suppose that Eurydice

was fondling and playing with a serpent that had slain her. Add to this

that Love seems to have been an inhabitant of the infernal regions, as

exhibited in the mysteries, for Claudian, who treats more openly of the

Eleusinian mysteries, when they were held in less veneration, invokes

the deities to disclose to him their secrets, and amongst other things

by what torch Love softens Pluto.

Dii, quibus in numerum, &c.

Vos mihi sacrarum penetralia pandite rerum,

Et vestri secreta poli, quâ lampade Ditem

Flexit amor.

In this compartment there are two trees, whose branches spread over the

figures, one of them has smoother leaves like some evergreens, and might

thence be supposed to have some allusion to immortality, but they may

perhaps have been designed only as ornaments, or to relieve the figures,

or because it was in groves, where these mysteries were originally

celebrated. Thus Homer speaks of the woods of Proserpine, and mentions

many trees in Tartarus, as presenting their fruits to Tantalus; Virgil

speaks of the pleasant groves of Elysium; and in Spence's Polymetis

there are prints of two antient gems, one of Orpheus charming Cerberus

with his lyre, and the other of Hercules binding him in a cord, each of

them standing by a tree. Polymet. p. 284. As however these trees have

all different foliage so clearly marked by the artist, they may have had

specific meanings in the exhibitions of the mysteries, which have not

reached posterity, of this kind seem to have been the tree of knowledge

of good and evil, and the tree of life, in sacred writ, both which must

have been emblematic or allegorical. The masks, hanging to the handles

of the vase, seem to indicate that there is a concealed meaning in the

figures besides their general appearance. And the priestess at the

bottom, which I come now to describe, seems to shew this concealed

meaning to be of the sacred or Eleusinian kind.

3. The figure on the bottom of the vase is on a larger scale than the

others, and less finely finished, and less elevated, and as this bottom

part was afterwards cemented to the upper part, it might be executed by

another artist for the sake of expedition, but there seems no reason to

suppose that it was not originally designed for the upper part of it as

some have conjectured. As the mysteries of Ceres were celebrated by

female priests, for Porphyrius says the antients called the priestesses

of Ceres, Melissai, or bees, which were emblems of chastity. Div. Leg.

Vol. I. p. 235. And as, in his Satire against the sex, Juvenal says,

that few women are worthy to be priestesses of Ceres. Sat. VI. the

figure at the bottom of the vase would seem to represent a PRIESTESS or

HIEROPHANT, whose office it was to introduce the initiated, and point

out to them, and explain the exhibitions in the mysteries, and to

exclude the uninitiated, calling out to them, "Far, far retire, ye

profane!" and to guard the secrets of the temple. Thus the introductory

hymn sung by the hierophant, according to Eusebius, begins, "I will

declare a secret to the initiated, but let the doors be shut against the

profane." Div. Leg. Vol. I. p. 177. The priestess or hierophant appears

in this figure with a close hood, and dressed in linen, which fits close

about her; except a light cloak, which flutters in the wind. Wool, as

taken from slaughtered animals, was esteemed profane by the priests of

Aegypt, who were always dressed in linen. Apuleus, p. 64. Div. Leg. Vol.

I. p. 318. Thus Eli made for Samuel a linen ephod. Samuel i. 3.

Secrecy was the foundation on which all mysteries rested, when publicly

known they ceased to be mysteries; hence a discovery of them was not

only punished with death by the Athenian law; but in other countries a

disgrace attended the breach of a solemn oath. The priestess in the

figure before us has her finger pointing to her lips as an emblem of

silence. There is a figure of Harpocrates, who was of Aegyptian origin,

the same as Orus, with the lotus on his head, and with his finger

pointing to his lips not pressed upon them, in Bryant's Mythol. Vol. II.

p. 398, and another female figure standing on a lotus, as if just risen

from the Nile, with her finger in the same attitude, these seem to have

been representations or emblems of male and female priests of the secret

mysteries. As these sort of emblems were frequently changed by artists

for their more elegant exhibition, it is possible the foliage over the

head of this figure may bear some analogy to the lotus above mentioned.

This figure of secrecy seems to be here placed, with great ingenuity, as

a caution to the initiated, who might understand the meaning of the

emblems round the vase, not to divulge it. And this circumstance seems

to account for there being no written explanation extant, and no

tradition concerning these beautiful figures handed down to us along

with them.

Another explanation of this figure at the bottom of the vase would seem

to confirm the idea that the basso relievos round its sides are

representations of a part of the mysteries, I mean that it is the head

of ATIS. Lucian says that Atis was a young man of Phrygia, of uncommon

beauty, that he dedicated a temple in Syria to Rhea, or Cybele, and

first taught her mysteries to the Lydians, Phrygians, and Samothracians,

which mysteries he brought from India. He was afterwards made an eunuch

by Rhea, and lived like a woman, and assumed a feminine habit, and in

that garb went over the world teaching her ceremonies and mysteries.

Dict. par M. Danet, art. Atis. As this figure is covered with clothes,

while those on the sides of the vase are naked, and has a Phrygian cap

on the head, and as the form and features are so soft, that it is

difficult to say whether it be a male or female figure, there is reason

to conclude, 1. that it has reference to some particular person of some

particular country; 2. that this person is Atis, the first great

hierophant, or teacher of mysteries, to whom M. De la Chausse says the

figure itself bears a resemblance. Museo. Capitol. Tom. IV. p. 402.

In the Museum Etruscum, Vol. I. plate 96, there is the head of Atis with

feminine features, clothed with a Phrygian cap, and rising from very

broad foliage, placed on a kind of term supported by the paw of a lion.

Goreus in his explanation of the figure says that it is placed on a

lion's foot because that animal was sacred to Cybele, and that it rises

from very broad leaves because after he became an eunuch he determined

to dwell in the groves. Thus the foliage, as well as the cap and

feminine features, confirm the idea of this figure at the bottom of the

vase representing the head of Atis the first great hierophant, and that

the figures on the sides of the vase are emblems from the antient

mysteries.

I beg leave to add that it does not appear to have been uncommon amongst

the antients to put allegorical figures on funeral vases. In the

Pamphili palace at Rome there is an elaborate representation of Life and

of Death, on an antient sarcophagus. In the first Prometheus is

represented making man, and Minerva is placing a butterfly, or the soul,

upon his head. In the other compartment Love extinguishes his torch in

the bosom of the dying figure, and is receiving the butterfly, or

Psyche, from him, with a great number of complicated emblematic figures

grouped in very bad taste. Admir. Roman. Antiq.

NOTE XXIII.--COAL

_Whence sable Coal his massy couch extends,

And stars of gold the sparkling Pyrite blends._

CANTO II. l. 349.

To elucidate the formation of coal-beds I shall here describe a fountain

of fossil tar, or petroleum, discovered lately near Colebrook Dale in

Shropshire, the particulars of which were sent me by Dr. Robert Darwin

of Shrewsbury.

About a mile and a half below the celebrated iron-bridge, constructed by

the late Mr. DARBY near Colebrook Dale, on the east side of the river

Severn, as the workmen in October 1786 were making a subterranean canal

into the mountain, for the more easy acquisition and conveyance of the

coals which lie under it, they found an oozing of liquid bitumen, or

petroleum; and as they proceeded further cut through small cavities of

different sizes from which the bitumen issued. From ten to fifteen

barrels of this fossil tar, each barrel containing thirty-two gallons,

were at first collected in a day, which has since however gradually

diminished in quantity, so that at present the product is about seven

barrels in fourteen days.

The mountain, into which this canal enters, consists of siliceous sand,

in which however a few marine productions, apparently in their recent

state, have been found, and are now in the possession of Mr. WILLIAM

REYNOLDS of Ketly Bank. About three hundred yards from the entrance into

the mountain, and about twenty-eight yards below the surface of it, the

tar is found oozing from the sand-rock above into the top and sides of

the canal.

Beneath the level of this canal a shaft has been sunk through a grey

argillaceous substance, called in this country clunch, which is said to

be a pretty certain indication of coal; beneath this lies a stratum of

coal, about two or three inches thick, of an inferior kind, yielding

little flame in burning, and leaving much ashes; below this is a rock of

a harder texture; and beneath this are found coals of an excellent

quality; for the purpose of procuring which with greater facility the

canal, or horizontal aperture, is now making into the mountain. July,

1788.

Beneath these coals in some places is found salt water, in other parts

of the adjacent country there are beds of iron-stone, which also contain

some bitumen in a less fluid state, and which are about on a level with

the new canal, into which the fossil tar oozes, as above described.

There are many interesting circumstances attending the situation and

accompaniments of this fountain of fossil tar, tending to develop the

manner of its production. 1. As the canal passing into the mountain runs

over the beds of coals, and under the reservoir of petroleum, it appears

that a _natural distillation_ of this fossil in the bowels of the earth

must have taken place at some early period of the world, similar to the

artificial distillation of coal, which has many years been carried on in

this place on a smaller scale above ground. When this reservoir of

petroleum was cut into, the slowness of its exsudation into the canal

was not only owing to its viscidity, but to the pressure of the

atmosphere, or to the necessity there was that air should at the same

time insinuate itself into the small cavities from which the petroleum

descended. The existence of such a distillation at some antient time is

confirmed by the thin stratum of coal beneath the canal, (which covers

the hard rock,) having been deprived of its fossil oil, so as to burn

without flame, and thus to have become a natural coak, or fossil

charcoal, while the petroleum distilled from it is found in the cavities

of the rock above it.

There are appearances in other places, which favour this idea of the

natural distillation of petroleum, thus at Matlock in Derbyshire a hard

bitumen is found adhering to the spar in the clefts of the lime-rocks in

the form of round drops about the size of peas; which could perhaps only

be deposited there in that form by sublimation.

2. The second deduction, which offers itself, is, that these beds of

coal have been _exposed to a considerable degree of heat_, since the

petroleum above could not be separated, as far as we know, by any other

means, and that the good quality of the coals beneath the hard rock was

owing to the impermeability of this rock to the bituminous vapour, and

to its pressure being too great to permit its being removed by the

elasticity of that vapour. Thus from the degree of heat, the degree of

pressure, and the permeability of the superincumbent strata, many of the

phenomena attending coal-beds receive an easy explanation, which much

accords with the ingenious theory of the earth by Dr. Hutton, Trans. of

Edinb. Vol. I.

In some coal works the fusion of the strata of coal has been so slight,

that there remains the appearance of ligneus fibres, and the impression

of leaves, as at Bovey near Exeter, and even seeds of vegetables, of

which I have had specimens from the collieries near Polesworth in

Warwickshire. In some, where the heat was not very intense and the

incumbent stratum not permeable to vapour, the fossil oil has only risen

to the upper part of the coal-bed, and has rendered that much more

inflammable than the lower parts of it, as in the collieries near

Beaudesert, the seat of the EARL OF UXBRIDGE in Staffordshire, where the

upper stratum is a perfect cannel, or candle-coal, and the lower one of

an inferior quality. Over the coal-beds near Sir H. HARPUR'S house in

Derbyshire a thin lamina of asphaltum is found in some places near the

surface of the earth, which would seem to be from a distillation of

petroleum from the coals below, the more fluid part of which had in

process of time exhaled, or been consolidated by its absorption of air.

In other coal-works the upper part of the stratum is of a worse kind

than the lower one, as at Alfreton and Denbigh in Derbyshire, owing to

the supercumbent stratum having permitted the exhalation of a great part

of the petroleum; whilst at Widdrington in Northumberland there is first

a seam of coal about six inches thick of no value, which lies under

about four fathom of clay, beneath this is a white freestone, then a

hard stone, which the workmen there call a whin, then two fathoms of

clay, then another white stone, and under that a vein of coals three

feet nine inches thick, of a similar nature to the Newcastle coal. Phil.

Trans. Abridg. Vol. VI. plate II. p. 192. The similitude between the

circumstances of this colliery, and of the coal beneath the fountain of

tar above described, renders it highly probable that this upper thin

seam of coal has suffered a similar distillation, and that the

inflammable part of it had either been received into the clay above in

the form of sulphur, which when burnt in the open air would produce

alum; or had been dissipated for want of a receiver, where it could be

condensed. The former opinion is perhaps in this case more probable as

in some other coal-beds, of which I have procured accounts, the surface

of the coal beneath clunch or clay is of an inferior quality, as at West

Hallum in Nottinghamshire. The clunch probably from hence acquires its

inflammable part, which on calcination becomes vitriolic acid. I

gathered pieces of clunch converted partially into alum at a colliery

near Bilston, where the ground was still on fire a few years ago.

The heat, which has thus pervaded the beds of morass, seems to have been

the effect of the fermentation of their vegetable materials; as new hay

sometimes takes fire even in such very small masses from the sugar it

contains, and seems hence not to have been attended with any expulsion

of lava, like the deeper craters of volcanos situated in beds of

granite.

3. The marine shells found in the loose sand-rock above this reservoir

of petroleum, and the coal-beds beneath it, together with the existence

of sea-salt beneath these coals, prove that these coal beds have been

_at the bottom of the sea_, during some remote period of time, and were

afterwards raised into their present situation by subterraneous

expansions of vapour. This doctrine is further supported by the marks of

violence, which some coal-beds received at the time they were raised out

of the sea, as in the collieries at Mendip in Somersetshire. In these

there are seven strata of coals, equitant upon each other, with beds of

clay and stone intervening; amongst which clay are found shells and fern

branches. In one part of this hill the strata are disjoined, and a

quantity of heterogeneous substances fill up the chasm which disjoins

them, on one side of this chasm the seven strata of coal are seen

corresponding in respect to their reciprocal thickness and goodness with

the seven strata on the other side of the cavity, except that they have

been elevated several yards higher. Phil. Trans. No. 360. abridg. Vol.

V. p. 237.

The cracks in the coal-bed near Ticknall in Derbyshire, and in the sand-

stone rock over it, in both of which specimens of lead-ore and spar are

found, confirm this opinion of their having been forcibly raised up by

subterraneous fires. Over the colliery at Brown-hills near Lichfield,

there is a stratum of gravel on the surface of the ground; which may be

adduced as another proof to shew that those coals had some time been

beneath the sea, or the bed of a river. Nevertheless, these arguments

only apply to the collieries above mentioned, which are few compared

with those which bear no marks of having been immersed in the sea.

On the other hand the production of coals from morasses, as described in

note XX. is evinced from the vegetable matters frequently found in them,

and in the strata over them; as fern-leaves in nodules of iron-ore, and

from the bog-shells or fresh water muscles sometimes found over them, of

both which I have what I believe to be specimens; and is further proved

from some parts of these beds being only in part transformed to coal;

and the other part still retaining not only the form, but some of the

properties of wood; specimens of which are not unfrequent in the

cabinets of the curious, procured from Loch Neigh in Ireland, from Bovey

near Exeter, and other places; and from a famous cavern called the

Temple of the Devil, near the town of Altorf in Franconia, at the foot

of a mountain covered with pine and savine, in which are found large

coals resembling trees of ebony; which are so far mineralized as to be

heavy and compact; and so to effloresce with pyrites in some parts as to

crumble to pieces; yet from other parts white ashes are produced on

calcination, from which _fixed alcali_ is procured; which evinces their

vegetable origin. (Dict. Raisonné, art. Charbon.) To these may be added

another argument from the oil which is distilled from coals, and which

is analogous to vegetable oil, and does not exist in any bodies truly

mineral. Keir's Chemical Dictionary, art. Bitumen.

Whence it would appear, that though most collieries with their attendant

strata of clay, sand-stone, and iron, were formed on the places where

the vegetables grew, from which they had their origin; yet that other

collections of vegetable matter were washed down from eminences by

currents of waters into the beds of rivers, or the neighbouring seas,

and were there accumulated at different periods of time, and underwent a

great degree of heat from their fermentation, in the same manner as

those beds of morass which had continued on the plains where they were

produced. And that by this fermentation many of them had been raised

from the ocean with sand and sea-shells over them; and others from the

beds of rivers with accumulations of gravel upon them.

4. For the purpose of bringing this history of the products of morasses

more distinctly to the eye of the reader, I shall here subjoin two or

three accounts of sinking or boring for coals, out of above twenty which

I have procured from various places, though the terms are not very

intelligible, being the language of the overseers of coal-works.

1. _Whitfield mine_ near the Pottery in Staffordshire. Soil 1 foot.

brick-clay 3 feet. shale 4. metal which is hard brown and falls in the

weather 42. coal 3. warrant clay 6. brown gritstone 36. coal 31/2. warrant

clay 31/2. bass and metal 531/2. hardstone 4. shaly bass 11/2. coal 4.

warrant clay, depth unknown. in all about 55 yards.

2. _Coal-mine at Alfreton_ in Derbyshire. Soil and clay 7 feet.

fragments of stone 9. bind 13. stone 6. bind 34. stone 5. bind 2. stone

2. bind 10. coal 11/2. bind 11/2. stone 37. bind 7. soft coal 3. bind 3.

stone 20. bind 16. coal 71/2. in all about 61 yards.

3. _A basset coal-mine at Woolarton_ in Nottinghamshire. Sand and gravel

6 feet. bind 21. stone 10. smut or effete coal 1. clunch 4. bind 21.

stone 18. bind 18. stone-bind 15. soft coal 2. clunch and bind 21. coal

7. in all about 48 yards.

4. _Coal-mine at West-Hallam_ in Nottinghamshire. Soil and clay 7 feet.

bind 48. smut 11/2. clunch 4. bind 3. stone 2. bind 1. stone 1. bind 3.

stone 1. bind 16. shale 2. bind 12. shale 3. clunch, stone, and a bed of

cank 54. soft coal 4. clay and dun 1. soft coal 41/2. clunch and bind 21.

coal 1. broad bind 26. hard coal 6. in all about 74 yards.

As these strata generally lie inclined, I suppose parallel with the

limestone on which they rest, the upper edges of them all come out to

day, which is termed bassetting; when the whole mass was ignited by its

fermentation, it is probable that the inflammable part of some strata

might thus more easily escape than of others in the form of vapour; as

dews are known to slide between such strata in the production of

springs; which accounts for some coal-beds being so much worse than

others. See note XX.

From this account of the production of coals from morasses it would

appear, that coal-beds are not to be expected beneath masses of lime-

stone. Nevertheless I have been lately informed by my friend Mr. Michell

of Thornhill, who I hope will soon favour the public with his geological

investigations, that the beds of chalk are the uppermost of all the

limestones; and that they rest on the granulated limestone, called

ketton-stone; which I suppose is similar to that which covers the whole

country from Leadenham to Sleaford, and from Sleaford to Lincoln; and

that, thirdly, coal-delphs are frequently found beneath these two

uppermost beds of limestone.

Now as the beds of chalk and of granulated limestone may have been

formed by alluviation, on or beneath the shores of the sea, or in

vallies of the land; it would seem, that some coal countries, which in

the great commotions of the earth had been sunk beneath the water, were

thus covered with alluvial limestone, as well as others with alluvial

basaltes, or common gravel-beds. Very extensive plains which now consist

of alluvial materials, were in the early times covered with water; which

has since diminished as the solid parts of the earth have increased. For

the solid parts of the earth consisting chiefly of animal and vegetable

recrements must have originally been formed or produced from the water

by animal and vegetable processes; and as the solid parts of the earth

may be supposed to be thrice as heavy as water, it follows that thrice

the quantity of water must have vanished compared with the quantity of

earth thus produced. This may account for many immense beds of alluvial

materials, as gravel, rounded sand granulated limestone, and chalk,

covering such extensive plains as Lincoln-heath, having become dry

without the supposition of their having been again elevated from the

ocean. At the same time we acquire the knowledge of one of the uses or

final causes of the organized world, not indeed very flattering to our

vanity, that it converts water into earth, forming islands and

continents by its recrements or exuviae.

NOTE XXIV.--GRANITE.

_Climb the rude steeps, the Granite-cliffs surround._

CANTO II. l. 523.

The lowest stratum of the earth which human labour has arrived to, is

granite; and of this likewise consists the highest mountains of the

world. It is known under variety of names according to some difference

in its appearance or composition, but is now generally considered by

philosophers as a species of lava; if it contains quartz, feltspat, and

mica in distinct crystals, it is called granite; which is found in

Cornwall in rocks; and in loose stones in the gravel near Drayton in

Shropshire, in the road towards Newcastle. If these parts of the

composition be less distinct, or if only two of them be visible to the

eye, it is termed porphyry, trap, whinstone, moorstone, slate. And if it

appears in a regular angular form, it is called basaltes. The affinity

of these bodies has lately been further well established by Dr. Beddoes

in the Phil. Trans. Vol. LXXX.

These are all esteemed to have been volcanic productions that have

undergone different degrees of heat; it is well known that in Papin's

digester water may be made red hot by confinement, and will then

dissolve many bodies which otherwise are little or not at all acted upon

by it. From hence it may be conceived, that under immense pressure of

superincumbent materials, and by great heat, these masses of lava may

have undergone a kind of aqueous solution, without any tendency to

vitrification, and might thence have a power of crystallization, whence

all the varieties above mentioned from the different proportion of the

materials, or the different degrees of heat they may have undergone in

this aqueous solution. And that the uniformity of the mixture of the

original earths, as of lime, argil, silex, magnesia, and barytes, which

they contain, was owing to their boiling together a longer or shorter

time before their elevation into mountains. See note XIX. art. 8.

The seat of volcanos seems to be principally, if not entirely, in these

strata of granite; as many of them are situated on granite mountains,

and throw up from time to time sheets of lava which run down over the

proceeding strata from the same origin; and in this they seem to differ

from the heat which has separated the clay, coal, and sand in morasses,

which would appear to have risen from a kind of fermentation, and thus

to have pervaded the whole mass without any expuition of lava.

[Illustration: _Section of the Earth. A sketch of a supposed Section of

the Earth in respect to the disposition of the Strata over each other

without regard to their proportions or number. London Published Dec'r

1st 1791 by J. Johnson St Paul's Church Yard._]

All the lavas from Vesuvius contain one fourth part of iron, (Kirwan's

Min.) and all the five primitive earths, viz. calcareous, argillaceous,

siliceous, barytic, and magnesian earths, which are also evidently

produced now daily from the recrements of animal and vegetable bodies.

What is to be thence concluded? Has the granite stratum in very antient

times been produced like the present calcareous and siliceous masses,

according to the ingenious theory of Dr. Hutton, who says new continents

are now forming at the bottom of the sea to rise in their turn, and that

thus the terraqueous globe has been, and will be, eternal? Or shall we

suppose that this internal heated mass of granite, which forms the

nucleus of the earth, was a part of the body of the sun before it was

separated by an explosion? Or was the sun originally a planet, inhabited

like ours, and a satellite to some other greater sun, which has long

been extinguished by diffusion of its light, and around which the

present sun continues to revolve, according to a conjecture of the

celebrated Mr. Herschell, and which conveys to the mind a most sublime

idea of the progressive and increasing excellence of the works of the

Creator of all things?

For the more easy comprehension of the facts and conjectures concerning

the situation and production of the various strata of the earth, I shall

here subjoin a supposed section of the globe, but without any attempt to

give the proportions of the parts, or the number of them, but only their

respective situation over each other, and a geological recapitulation.

GEOLOGICAL RECAPITULATION.

1. The earth was projected along with the other primary planets from the

sun, which is supposed to be on fire only on its surface, emitting light

without much internal heat like a ball of burning camphor.

2. The rotation of the earth round its axis was occasioned by its

greater friction or adhesion to one side of the cavity from which it was

ejected; and from this rotation it acquired its spheroidical form. As it

cooled in its ascent from the sun its nucleus became harder; and its

attendant vapours were condensed, forming the ocean.

3. The masses or mountains of granite, porphery, basalt, and stones of

similar structure, were a part of the original nucleus of the earth; or

consist of volcanic productions since formed.

4. On this nucleus of granite and basaltes, thus covered by the ocean,

were formed the calcareous beds of limestone, marble, chalk, spar, from

the exuviae of marine animals; with the flints, or chertz, which

accompany them. And were stratified by their having been formed at

different and very distant periods of time.

5. The whole terraqueous globe was burst by central fires; islands and

continents were raised, consisting of granite or lava in some parts, and

of limestone in others; and great vallies were sunk, into which the

ocean retired.

6. During these central earthquakes the moon was ejected from the earth,

causing new tides; and the earth's axis suffered some change in its

inclination, and its rotatory motion was retarded.

7. On some parts of these islands and continents of granite or limestone

were gradually produced extensive morasses from the recrements of

vegetables and of land animals; and from these morasses, heated by

fermentation, were produced clay, marle, sandstone, coal, iron, (with

the bases of variety of acids;) all which were stratified by their

having been formed at different, and very distant periods of time.

8. In the elevation of the mountains very numerous and deep fissures

necessarily were produced. In these fissures many of the metals are

formed partly from descending materials, and partly from ascending ones

raised in vapour by subterraneous fires. In the fissures of granite or

porphery quartz is formed; in the fissures of limestone calcareous spar

is produced.

9. During these first great volcanic fires it is probable the atmosphere

was either produced, or much increased; a process which is perhaps now

going on in the moon; Mr. Herschell having discovered a volcanic crater

three miles broad burning on her disk.

10. The summits of the new mountains were cracked into innumerable

lozenges by the cold dews or snows falling upon them when red hot. From

these summits, which were then twice as high as at present, cubes and

lozenges of granite, and basalt, and quartz in some countries, and of

marble and flints in others, descended gradually into the valleys, and

were rolled together in the beds of rivers, (which were then so large as

to occupy the whole valleys, which they now only intersect;) and

produced the great beds of gravel, of which many valleys consist.

11. In several parts of the earth's surface subsequent earthquakes, from

the fermentation of morasses, have at different periods of time deranged

the position of the matters above described. Hence the gravel, which was

before in the beds of rivers, has in some places been raised into

mountains, along with clay and coal strata which were formed from

morasses and washed down from eminences into the beds of rivers or the

neighbouring seas, and in part raised again with gravel or marine shells

over them; but this has only obtained in few places compared with the

general distribution of such materials. Hence there seem to have existed

two sources of earthquakes, which have occurred at great distance of

time from each other; one from the granite beds in the central parts of

the earth, and the other from the morasses on its surface. All the

subsequent earthquakes and volcanos of modern days compared with these

are of small extent and insignificant effect.

12. Besides the argillaceous sand-stone produced from morasses, which is

stratified with clay, and coal, and iron, other great beds of siliceous

sand have been formed in the sea by the combination of an unknown acid

from morasses, and the calcareous matters of the ocean.

13. The warm waters which are found in many countries, are owing to

steam arising from great depths through the fissures of limestone or

lava, elevated by subterranean fires, and condensed between the strata

of the hills over them; and not from any decomposition of pyrites or

manganese near the surface of the earth.

14. The columns of basaltes have been raised by the congelation or

expansion of granite beds in the act of cooling from their semi-vitreous

fusion.

NOTE XXV.--EVAPORATION.

_Aquatic nymphs! you lead with viewless march

The winged vapour up the aerial arch._

CANTO III. l. 13.

I. The atmosphere will dissolve a certain quantity of moisture as a

chemical menstruum, even when it is much below the freezing point, as

appears from the diminution of ice suspended in frosty air, but a much

greater quantity of water is evaporated and suspended in the air by

means of heat, which is perhaps the universal cause of fluidity, for

water is known to boil with less heat in vacuo, which is a proof that it

will evaporate faster in vacuo, and that the air therefore rather

hinders than promotes its evaporation in higher degrees of heat. The

quick evaporation occasioned in vacuo by a small degree of heat is

agreeably seen in what is termed a pulse-glass, which consists of an

exhausted tube of glass with a bulb at each end of it and with about two

thirds of the cavity filled with alcohol, in which the spirit is

instantly seen to boil by the heat of the finger-end applied on a bubble

of steam in the lower bulb, and is condensed again in the upper bulb by

the least conceivable comparative coldness.

2. Another circumstance evincing that heat is the principal cause of

evaporation is that at the time of water being converted into steam, a

great quantity of heat is taken away from the neighbouring bodies. If a

thermometer be repeatedly dipped in ether, or in rectified spirit of

wine, and exposed to a blast of air, to expedite the evaporation by

perpetually removing the saturated air from it, the thermometer will

presently sink below freezing. This warmth, taken from the ambient

bodies at the time of evaporation by the steam, is again given out when

the steam is condensed into water. Hence the water in a worm-tub during

distillation so soon becomes hot; and hence the warmth accompanying the

descent of rain in cold weather.

3. The third circumstance, shewing that heat is the principal cause of

evaporation, is, that some of the steam becomes again condensed when any

part of the heat is withdrawn. Thus when warmer south-west winds replete

with moisture succeed the colder north-east winds all bodies that are

dense and substantial, as stone walls, brick floors, &c. absorb some of

the heat from the passing air, and its moisture becomes precipitated on

them, while the north-east winds become warmer on their arrival in this

latitude, and are thence disposed to take up more moisture, and are

termed drying winds.

4. Heat seems to be the principal cause of the solution of many other

bodies, as common salt, or blue vitriol dissolved in water, which when

exposed to severe cold are precipitated, or carried, to the part of the

water last frozen; this I observed in a phial filled with a solution of

blue vitriol which was frozen; the phial was burst, the ice thawed, and

a blue column of cupreous vitriol was left standing upright on the

bottom of the broken glass, as described in note XIX.

II. Hence water may either be dissolved in air, and may then be called

an aerial solution of water; or it may be dissolved in the fluid matter

of heat, according to the theory of M. Lavoisier, and may then be called

steam. In the former case it is probable there are many other vapours

which may precipitate it, as marine acid gas, or fluor acid gas. So

alcaline gas and acid gas dissolved in air precipitate each other,

nitrous gas precipitates vital air from its azote, and inflammable gas

mixed with vital air ignited by an electric spark either produces or

precipitates the water in both of them. Are there any subtle exhalations

occasionally diffused in the atmosphere which may thus cause rain?

1. But as water is perhaps many hundred times more soluble in the fluid

matter of heat than in air, I suppose the eduction of this heat, by

whatever means it is occasioned, is the principal cause of devaporation.

Thus if a region of air is brought from a warmer climate, as the S.W.

winds, it becomes cooled by its contact with the earth in this latitude,

and parts with so much of its moisture as was dissolved in the quantity

of calorique, or heat, which it now looses, but retains that part which

was suspended by its attraction to the particles of air, or by aerial

solution, even in the most severe frosts.

2. A second immediate cause of rain is a stream of N.E. wind descending

from a superior current of air, and mixing with the warmer S.W. wind

below; or the reverse of this, viz. a superior current of S.W. wind

mixing with an inferior one of N.E. wind; in both these cases the whole

heaven becomes instantly clouded, and the moisture contained in the S.W.

current is precipitated. This cause of devaporation has been ingeniously

explained by Dr. Hutton in the Transact. of Edinburgh, Vol. I, and seems

to arise from this circumstance; the particles of air of the N.E. wind

educe part of the heat from the S.W. wind, and therefore the water which

was dissolved by that quantity of _heat_ is precipitated; all the other

part of the water, which was suspended by its attraction to the

particles of air, or dissolved in the remainder of the heat, continues

unprecipitated.

3. A third method by which a region of air becomes cooled, and in

consequence deposits much of its moisture, is from the mechanical

expansion of air, when part of the pressure is taken off. In this case

the expanded air becomes capable of receiving or attracting more of the

matter of heat into its interstices, and the vapour, which was

previously dissolved in this heat, is deposited, as is seen in the

receiver of an air-pump, which becomes dewy, as the air within becomes

expanded by the eduction of part of it. See note VII. Hence when the

mercury in the barometer sinks without a change of the wind the air

generally becomes colder. See note VII. on Elementary Heat. And it is

probably from the varying pressure of the incumbent air that in summer

days small black clouds are often thus suddenly produced, and again soon

vanish. See a paper in Philos. Trans. Vol. LXXVIII. intitled Frigorific

Experiments on the Mechanical Expansion of Air.

4. Another portion of atmospheric water may possibly be held in solution

by the electric fluid, since in thunder storms a precipitation of the

water seems to be either the cause or the consequence of the eduction of

the electricity. But it appears more probable that the water is

condensed into clouds by the eduction of its heat, and that then the

surplus of electricity prevents their coalescence into larger drops,

which immediately succeeds the departure of the lightning.

5. The immediate cause why the barometer sinks before rain is, first,

because a region of warm air, brought to us in the place of the cold air

which it had displaced, must weigh lighter, both specifically and

absolutely, if the height of the warm atmosphere be supposed to be equal

to that of the preceeding cold one. And secondly, after the drops of

rain begin to fall in any column of air, that column becomes lighter,

the falling drops only adding to the pressure of the air in proportion

to the resistance which they meet with in passing through that fluid.

If we could suppose water to be dissolved in air without heat, or in

very low degrees of heat, I suppose the air would become heavier, as

happens in many chemical solutions, but if water dissolved in the matter

of heat, or calorique, be mixed with an aerial solution of water, there

can be no doubt but an atmosphere consisting of such a mixture must

become lighter in proportion to the quantity of calorique. On the same

circumstance depends the visible vapour produced from the breath of

animals in cold weather, or from a boiling kettle; the particles of cold

air, with which it is mixed, steal a part of its heat, and become

themselves raised in temperature, whence part of the water is

precipitated in visible vapour, which, if in great quantity sinks to the

ground; if in small quantity, and the surrounding air is not previously

saturated, it spreads itself till it becomes again dissolved.

NOTE XXVI.--SPRINGS

_Your lucid bands condense with fingers chill

The blue mist hovering round the gelid hill_.

CANTO III. l. 19.

The surface of the earth consists of strata many of which were formed

originally beneath the sea, the mountains were afterwards forced up by

subterraneous fires, as appears from the fissures in the rocks of which

they consist, the quantity of volcanic productions all over the world,

and the numerous remains of craters of volcanos in mountainous

countries. Hence the strata which compose the sides of mountains lie

slanting downwards, and one or two or more of the external strata not

reaching to the summit when the mountain was raised up, the second or

third stratum or a more inferior one is there exposed to day; this may

be well represented by forceably thrusting a blunt instrument through

several sheets of paper, a bur will stand up with the lowermost sheet

standing highest in the center of it. On this uppermost stratum, which

is colder as it is more elevated, the dews are condensed in large

quantities; and sliding down pass under the first or second or third

stratum which compose the sides of the hill; and either form a morass

below, or a weeping rock, by oozing out in numerous places, or many of

these less currents meeting together burst out in a more copious rill.

The summits of mountains are much colder than the plains in their

vicinity, owing to several causes; 1. Their being in a manner insulated

or cut off from the common heat of the earth, which is always of 48

degrees, and perpetually counteracts the effects of external cold

beneath that degree. 2. From their surfaces being larger in proportion

to their solid contents, and hence their heat more expeditiously carried

away by the ever-moving atmosphere. 3. The increasing rarity of the air

as the mountain rises. All those bodies which conduct electricity well

or ill, conduct the matter of heat likewise well or ill. See note VII.

Atmospheric air is a bad conductor of electricity and thence confines it

on the body where it is accumulated, but when it is made very rare, as

in the exhausted receiver, the electric aura passes away immediately to

any distance. The same circumstance probably happens in respect to heat,

which is thus kept by the denser air on the plains from escaping, but is

dissipated on the hills where the air is thinner. 4. As the currents of

air rise up the sides of mountains they become mechanically rarefied,

the pressure of the incumbent column lessening as they ascend. Hence the

expanding air absorbs heat from the mountain as it ascends, as explained

in note VII. 5. There is another, and perhaps more powerful cause, I

suspect, which may occasion the great cold on mountains, and in the

higher parts of the atmosphere, and which has not yet been attended to;

I mean that the fluid matter of heat may probably gravitate round the

earth, and form an atmosphere on its surface, mixed with the aerial

atmosphere, which may diminish or become rarer, as it recedes from the

earth's surface, in a greater proportion than the air diminishes.

6. The great condensation of moisture on the summits of hills has

another cause, which is the dashing of moving clouds against them, in

misty days this is often seen to have great effect on plains, where an

eminent tree by obstructing the mist as it moves along shall have a much

greater quantity of moisture drop from its leaves than falls at the same

time on the ground in its vicinity. Mr. White, in his History of

Selborne gives an account of a large tree so situated, from which a

stream flowed during a moving mist so as to fill the cart-ruts in a lane

otherwise not very moist, and ingeniously adds, that trees planted about

ponds of stagnant water contribute much by these means to supply the

reservoir. The spherules which constitute a mist or cloud are kept from

uniting by so small a power that a little agitation against the leaves

of a tree, or the greater attraction of a flat moist surface, condenses

or precipitates them.

If a leaf has its surface moistened and particles of water separate from

each other as in a mist be brought near the moistened surface of a leaf,

each particle will be attracted more by that plain surface of water on

the leaf than it can be by the surrounding particles of the mist,

because globules only attract each other in one point, whereas a plain

attracts a globule by a greater extent of its surface.

The common cold springs are thus formed on elevated grounds by the

condensed vapours, and hence are stronger when the nights are cold after

hot days in spring, than even in the wet days of winter. For the warm

atmosphere during the day has dissolved much more water than it can

support in solution during the cold of the night, which is thus

deposited in large quantities on the hills, and yet so gradually as to

soak in between the strata of them, rather than to slide off over their

surfaces like showers of rain. The common heat of the internal parts of

the earth is ascertained by springs which arise from strata of earth too

deep to be affected by the heat of summer or the frosts of winter. Those

in this country are of 48 degrees of heat, those about Philidelphia were

said by Dr. Franklin to be 52; whether this variation is to be accounted

for by the difference of the sun's heat on that country, according to

the ingenious theory of Mr. Kirwan, or to the vicinity of subterranean

fires is not yet, I think, decided. There are however subterraneous

streams of water not exactly produced in this manner, as streams issuing

from fissures in the earth, communicating with the craters of old

volcanoes; in the Peak of Derbyshire are many hollows, called swallows,

where the land floods sink into the earth, and come out at some miles

distant, as at Ilam near Ashborne. See note on Fica, Vol. II.

Other streams of cold water arise from beneath the snow on the Alps and

Andes, and other high mountains, which is perpetualy thawing at its

under surface by the common heat of the earth, and gives rise to large

rivers. For the origin of warm springs see note on Fucus, Vol. II.

NOTE XXVII.--SHELL FISH.

_You round Echinus ray his arrowy mail,

Give the keel'd Nautilus his oar and sail.

Firm to his rock with silver cords suspend

The anchored Pinna, and his Cancer-friend_.

CANTO III. l. 67.

The armour of the Echinus, or Sea-hedge Hog, consists generally of

moveable spines; (_Linnei System. Nat._ Vol. I. p. 1102.) and in that

respect resembles the armour of the land animal of the same name. The

irregular protuberances on other sea-shells, as on some species of the

Purpura, and Murex, serve them as a fortification against the attacks of

their enemies.

It is said that this animal foresees tempestuous weather, and sinking to

the bottom of the sea adheres firmly to sea-plants, or other bodies by

means of a substance which resembles the horns of snails. Above twelve

hundred of these fillets have been counted by which this animal fixes

itself; and when afloat, it contracts these fillets between the bases of

its points, the number of which often amounts to two thousand. Dict

raisonne. art. Oursin. de mer.

There is a kind of Nautilus, called by Linneus, Argonauta, whose shell

has but one cell; of this animal Pliny affirms, that having exonerated

its shell by throwing out the water, it swims upon the surface,

extending a web of wonderful tenuity, and bending back two of its arms

and rowing with the rest, makes a sail, and at length receiving the

water dives again. Plin. IX. 29. Linneus adds to his description of this

animal, that like the Crab Diogenes or Bernhard, it occupies a house

not its own, as it is not connected to its shell, and is therefore

foreign to it; who could have given credit to this if it had not been

attested by so many who have with their own eyes seen this argonaut in

the act of sailing? Syst. Nat p. 1161.

The Nautilus, properly so named by Linneus, has a shell consisting of

many chambers, of which cups are made in the East with beautiful

painting and carving on the mother-pearl. The animal is said to inhabit

only the uppermost or open chamber, which is larger than the rest; and

that the rest remain empty except that the pipe, or siphunculus, which

communicates from one to the other of them is filled with an appendage

of the animal like a gut or string. Mr. Hook in his Philos. Exper. p.

306, imagines this to be a dilatable or compressible tube, like the air-

bladders of fish, and that by contracting or permitting it to expand, it

renders its shell boyant or the contrary. See Note on Ulva, Vol. II.

The Pinna, or Sea-wing, is contained in a two-valve shell, weighing

sometimes fifteen pounds, and emits a beard of fine long glossy silk-

like fibres, by which it is suspended to the rocks twenty or thirty feet

beneath the surface of the sea. In this situation it is so successfully

attacked by the eight-footed Polypus, that the species perhaps could not

exist but for the exertions of the Cancer Pinnotheris, who lives in the

same shell as a guard and companion. Amoen. Academ. Vol. II. p. 48. Lin.

Syst. Nat. Vol. I. p. 1159, and p. 1040.

The Pinnotheris, or Pinnophylax, is a small crab naked like Bernard the

Hermit, but is furnished with good eyes, and lives in the same shell

with the Pinna; when they want food the Pinna opens its shell, and sends

its faithful ally to forage; but if the Cancer sees the Polypus, he

returns suddenly to the arms of his blind hostess, who by closing the

shell avoids the fury of her enemy; otherwise, when it has procured a

booty, it brings it to the opening of the shell, where it is admitted,

and they divide the prey. This was observed by Haslequist in his voyage

to Palestine.

The Byssus of the antients, according to Aristotle, was the beard of the

Pinna above mentioned, but seems to have been used by other writers

indiscriminately for any spun material, which was esteemed finer or more

valuable than wool. Reaumur says the threads of this Byssus are not less

fine or less beautiful than the silk, as it is spun by the silk-worm;

the Pinna on the coasts of Italy and Provence (where it is fished up by

iron-hooks fixed on long poles) is called the silk-worm of the sea. The

stockings and gloves manufactured from it, are of exquisite fineness,

but too warm for common wear, and are thence esteemed useful in

rhumatism and gout. Dict. raisonné art. Pinne-marine. The warmth of the

Byssus, like that of silk, is probably owing to their being bad

conductors of heat, as well as of electricity. When these fibres are

broken by violence, this animal as well as the muscle has the power to

reproduce them like the common spiders, as was observed by M. Adanson.

As raw silk, and raw cobwebs, when swallowed, are liable to produce

great sickness (as I am informed) it is probable the part of muscles,

which sometimes disagrees with the people who eat them, may be this

silky web, by which they attach themselves to stones. The large kind of

Pinna contains some mother-pearl of a reddish tinge, according to M.

d'Argenville. The substance sold under the name of Indian weed, and used

at the bottom of fish-lines, is probably a production of this kind;

which however is scarcely to be distinguished by the eye from the

tendons of a rat's tail, after they have been separated by putrefaction

in water, and well cleaned and rubbed; a production, which I was once

shewn as a great curiosity; it had the uppermost bone of the tail

adhering to it, and was said to have been used as an ornament in a

lady's hair.

NOTE XXVIII.--STURGEON.

_With worm-like hard his toothless lips array,

And teach the unweildy Sturgeon to betray._

CANTO III. l. 71.

The Sturgeon, _Acipenser, Strurio._ Lin. Syst. Nat. Vol. I. p. 403. is a

fish of great curiosity as well as of great importance; his mouth is

placed under the head, without teeth, like the opening of a purse, which

he has the power to push suddenly out or retract. Before this mouth

under the beak or nose hang four tendrils some inches long, and which so

resemble earth-worms that at first sight they may be mistaken for them.

This clumsy toothless fish is supposed by this contrivance to keep

himself in good condition, the solidity of his flesh evidently shewing

him to be a fish of prey. He is said to hide his large body amongst the

weeds near the sea-coast, or at the mouths of large rivers, only

exposing his cirrhi or tendrils, which small fish or sea-insects

mistaking for real worms approach for plunder, and are sucked into the

jaws of their enemy. He has been supposed by some to root into the soil

at the bottom of the sea or rivers; but the cirrhi, or tendrills

abovementioned, which hang from his snout over his mouth, must

themselves be very inconvenient for this purpose, and as it has no jaws

it evidently lives by suction, and during its residence in the sea a

quantity of sea-insects are found in its stomach.

The flesh was so valued in the time of the Emperor Severus, that it was

brought to table by servants with coronets on their heads, and preceded

by music, which might give rise to its being in our country presented by

the Lord Mayor to the King. At present it is caught in the Danube, and

the Walga, the Don, and other large rivers for various purposes. The

skin makes the best covering for carriages; isinglass is prepared from

parts of the skin; cavear from the spawn; and the flesh is pickled or

salted, and sent all over Europe.

NOTE XXIX.--OIL ON WATER.

_Who with fine films, suspended o'er the deep,

Of Oil effusive lull the waves to sleep._

CANTO III. l. 87.

There is reason to believe that when oil is poured upon water, the two

surfaces do not touch each other, but that the oil is suspended over the

water by their mutual repulsion. This seems to be rendered probable by

the following experiment: if one drop of oil be droped on a bason of

water, it will immediately diffuse itself over the whole, for there

being no friction between the two surfaces, there is nothing to prevent

its spreading itself by the gravity of the upper part of it, except its

own tenacity, into a pellicle of the greatest tenuity. But if a second

drop of oil be put upon the former, it does not spread itself, but

remains in the form of a drop, as the other already occupied the whole

surface of the bason, and there is friction in oil passing over oil,

though none in oil passing over water.

Hence when oil is diffused on the surface of water gentle breezes have

no influence in raising waves upon it; for a small quantity of oil will

cover a very great surface of water, (I suppose a spoonful will diffuse

itself over some acres) and the wind blowing upon this carries it

gradually forwards; and there being no friction between the two surfaces

the water is not affected. On which account oil has no effect in

stilling the agitation of the water after the wind ceases, as was found

by the experiments of Dr. Franklin.

This circumstance lately brought into notice by Dr. Franklin had been

mentioned by Pliny, and is said to be in use by the divers for pearls,

who in windy weather take down with them a little oil in their mouths,

which they occasionally give out when the inequality of the supernatant

waves prevents them from seeing sufficiently distinctly for their

purpose.

The wonderful tenuity with which oil can be spread upon water is evinced

by a few drops projected from a bridge, where the eye is properly placed

over it, passing through all the prismatic colours as it diffuses

itself. And also from another curious experiment of Dr. Franklin's: he

cut a piece of cork to about the size of a letter-wafer, leaving a point

standing off like a tangent at one edge of the circle. This piece of

cork was then dipped in oil and thrown into a large pond of water, and

as the oil flowed off at the point, the cork-wafer continued to revolve

in a contrary direction for several minutes. The oil flowing off all

that time at the pointed tangent in coloured streams. In a small pond of

water this experiment does not so well succeed, as the circulation of

the cork stops as soon as the water becomes covered with the pellicle of

oil. See Additional Note, No. XIII. and Note on Fucus, Vol. II.

The ease with which oil and water slide over each other is agreeably

seen if a phial be about half filled with equal parts of oil and water,

and made to oscillate suspended by a string, the upper surface of the

oil and the lower one of the water will always keep smooth; but the

agitation of the surfaces where the oil and water meet, is curious; for

their specific gravities being not very different, and their friction on

each other nothing, the highest side of the water, as the phial descends

in its oscillation, having acquired a greater momentum than the lowest

side (from its having descended further) would rise the highest on the

ascending side of the oscillation, and thence pushes the then uppermost

part of the water amongst the oil.

NOTE XXX.--SHIP-WORM.

_Meet fell Teredo, as he mines the keel

With beaked head, and break his lips of steel._

CANTO III. l. 91.

The Teredo, or ship-worm, has two calcareous jaws, hemispherical, flat

before, and angular behind. The shell is taper, winding, penetrating

ships and submarine wood, and was brought from India into Europe, Linnei

System. Nat. p. 1267. The Tarieres, or sea-worms, attack and erode ships

with such fury, and in such numbers, as often greatly to endanger them.

It is said that our vessels have not known this new enemy above fifty

years, that they were brought from the sea about the Antilles to our

parts of the ocean, where they have increased prodigiously. They bore

their passage in the direction of the fibres of the wood, which is their

nourishment, and cannot return or pass obliquely, and thence when they

come to a knot in the wood, or when two of them meet together with their

stony mouths, they perish for want of food.

In the years 1731 and 1732 the United Provinces were under a dreadful

alarm concerning these insects, which had made great depredation on the

piles which support the banks of Zeland, but it was happily discovered a

few years afterwards that these insects had totally abandoned that

island, (Dict Raisonné, art, Vers Rongeurs,) which might have been

occasioned by their not being able to live in that latitude when the

winter was rather severer than usual.

NOTE XXXI.--MAELSTROM.

_Turn the broad helm, the fluttering canvas urge

From Maelstrom's fierce innavigable surge._

CANTO III. l. 93.

On the coast of Norway there is an extensive vortex, or eddy, which lies

between the islands of Moskoe and Moskenas, and is called Moskoestrom,

or Maelstrom; it occupies some leagues in circumference, and is said to

be very dangerous and often destructive to vessels navigating these

seas. It is not easy to understand the existence of a constant

descending stream without supposing it must pass through a subterranean

cavity to some other part of the earth or ocean which may lie beneath

its level; as the Mediterranean seems to lie beneath the level of the

Atlantic ocean, which therefore constantly flows into it through the

Straits; and the waters of the Gulph of Mexico lie much above the level

of the sea about the Floridas and further northward, which gives rise to

the Gulph-stream, as described in note on Cassia in Vol. II.

The Maelstrom is said to be still twice in about twenty-four hours when

the tide is up, and most violent at the opposite times of the day. This

is not difficult to account for, since when so much water is brought

over the subterraneous passage, if such exists, as compleatly to fill it

and stand many feet above it, less disturbance must appear on the

surface. The Maelstrom is described in the Memoires of the Swedish

Academy of Sciences, and Pontoppiden's Hist. of Norway, and in Universal

Museum for 1763, p. 131.

The reason why eddies of water become hollow in the middle is because

the water immediately over the centre of the well, or cavity, falls

faster, having less friction to oppose its descent, than the water over

the circumference or edges of the well. The circular motion or gyration

of eddies depends on the obliquity of the course of the stream, or to

the friction or opposition to it being greater on one side of the well

than the other; I have observed in water passing through a hole in the

bottom of a trough, which was always kept full, the gyration of the

stream might be turned either way by increasing the opposition of one

side of the eddy with ones finger, or by turning the spout, through

which the water was introduced, a little more obliquely to the hole on

one side or on the other. Lighter bodies are liable to be retained long

in eddies of water, while those rather heavier than water are soon

thrown out beyond the circumference by their acquired momentum becoming

greater than that of the water. Thus if equal portions of oil and water

be put into a phial, and by means of a string be whirled in a circle

round the hand, the water will always keep at the greater distance from

the centre, whence in the eddies formed in rivers during a flood a

person who endeavours to keep above water or to swim is liable to be

detained in them, but on suffering himself to sink or dive he is said

readily to escape. This circulation of water in descending through a

hole in a vessel Dr. Franklin has ingeniously applied to the explanation

of hurricanes or eddies of air.

NOTE XXXII.--GLACIERS.

_While round dark crags imprison'd waters bend

Through rifted ice, in ivory veins descend._

CANTO III. l. 113.

The common heat of the interior parts of the earth being always 48

degrees, both in winter and summer, the snow which lies in contact with

it is always in a thawing state; Hence in ice-houses the external parts

of the collection of ice is perpetually thawing and thus preserves the

internal part of it; so that it is necessary to lay up many tons for the

preservation of one ton. Hence in Italy considerable rivers have their

source from beneath the eternal glaciers, or mountains of snow and ice.

In our country when the air in the course of a frost continues a day or

two at very near 32 degrees, the common heat of the earth thaws the ice

on its surface, while the thermometer remains at the freezing point.

This circumstance is often observable in the rimy mornings of spring;

the thermometer shall continue at the freezing point, yet all the rime

will vanish, except that which happens to lie on a bridge, a board, or

on a cake of cow-dung, which being thus as it were insulated or cut off

from so free a communication with the common heat of the earth by means

of the air under the bridge, or wood, or dung, which are bad conductors

of heat, continues some time longer unthawed. Hence when the ground is

covered thick with snow, though the frost continues, and the sun does

not shine, yet the snow is observed to decrease very sensibly. For the

common heat of the earth melts the under surface of it, and the upper

one evaporates by its solution in the air. The great evaporation of ice

was observed by Mr. Boyle, which experiment I repeated some time ago.

Having suspended a piece of ice by a wire and weighed it with care

without touching it with my hand, I hung it out the whole of a clear

frosty night, and found in the morning it had lost nearly a fifth of its

weight. Mr. N. Wallerius has since observed that ice at the time of its

congelation evaporates faster than water in its fluid form; which may be

accounted for from the heat given out at the instant of freezing;

(Saussure's Essais sur Hygromet. p. 249.) but this effect is only

momentary.

Thus the vegetables that are covered with snow are seldom injured;

since, as they lie between the thawing snow, which has 32 degrees of

heat, and the covered earth which has 48, they are preserved in a degree

of heat between these; viz. in 40 degrees of heat. Whence the moss on

which the rein-deer feed in the northern latitudes vegetates beneath the

snow; (See note on Muschus, Vol. II.) and hence many Lapland and Alpine

plants perished through cold in the botanic garden at Upsal, for in

their native situations, though the cold is much more intense, yet at

its very commencement they are covered deep with snow, which remains

till late in the spring. For this fact see Amaenit. Academ. Vol. I. No.

48. In our climate such plants do well covered with dried fern, under

which they will grow, and even flower, till the severe vernal frosts

cease. For the increase of glaciers see Note on Canto I. l. 529.

NOTE XXXIII.--WINDS.

_While southern gales o'er western oceans roll,

And Eurus steals his ice-winds from the pole._

CANTO IV. l. 15.

The theory of the winds is yet very imperfect, in part perhaps owing to

the want of observations sufficiently numerous of the exact times and

places where they begin and cease to blow, but chiefly to our yet

imperfect knowledge of the means by which great regions of air are

either suddenly produced or suddenly destroyed.

The air is perpetually subject to increase or diminution from its

combination with other bodies, or its evolution from them. The vital

part of the air, called oxygene, is continually produced in this climate

from the perspiration of vegetables in the sunshine, and probably from

the action of light on clouds or on water in the tropical climates,

where the sun has greater power, and may exert some yet unknown laws of

luminous combination. Another part of the atmosphere, which is called

azote, is perpetually set at liberty from animal and vegetable bodies by

putrefaction or combustion, from many springs of water, from volatile

alcali, and probably from fixed alcali, of which there is an exhaustless

source in the water of the ocean. Both these component parts of the air

are perpetually again diminished by their contact with the soil, which

covers the surface of the earth, producing nitre. The oxygene is

diminished in the production of all acids, of which the carbonic and

muriatic exist in great abundance. The azote is diminished in the growth

of animal bodies, of which it constitutes an important part, and in its

combinations with many other natural productions.

They are both probably diminished in immense quantities by uniting with

the inflammable air, which arises from the mud of rivers and lakes at

some seasons, when the atmosphere is light: the oxygene of the air

producing water, and the azote producing volatile alcali by their

combinations with this inflammable air. At other seasons of the year

these principles may again change their combinations, and the

atmospheric air be reproduced.

Mr. Lavoisier found that one pound of charcoal in burning consumed two

pounds nine ounces of vital air, or oxygene. The consumption of vital

air in the process of making red lead may readily be reduced to

calculation; a small barrel contains about twelve hundred weight of this

commodity, 1200 pounds of lead by calcination absorb about 144 pounds of

vital air; now as a cubic foot of water weighs 1000 averdupois ounces,

and as vital air is above 800 times lighter than water, it follows that

every barrel of red lead contains nearly 2000 cubic feet of vital air.

If this can be performed in miniature in a small oven, what may not be

done in the immense elaboratories of nature!

These great elaboratories of nature include almost all her fossil as

well as her animal and vegetable productions. Dr. Priestley obtained air

of greater or less purity, both vital and azotic, from almost all the

fossil substances he subjected to experiment. Four ounce-weight of lava

from Iceland heated in an earthen retort yielded twenty ounce-measures

of air.

4 ounce-weight of lava gave 20 ounce measures of air.

7 ............... basaltes .... 104 ......................

2 ............... toadstone .... 40 ......................

11/2 ............... granite .... 20 ......................

1 ............... elvain .... 30 ......................

7 ............... gypsum .... 230 ......................

4 ............... blue slate .... 230 ......................

4 ............... clay .... 20 ......................

4 ............... limestone-spar .... 830 ......................

5 ............... limestone .... 1160 ......................

3 ............... chalk .... 630 ......................

31/2 ............... white iron-ore .... 560 ......................

4 ............... dark iron-ore .... 410 ......................

1/2 ............... molybdena .... 25 ......................

1/2 ............... stream tin .... 20 ......................

2 ............... steatites .... 40 ......................

2 ............... barytes .... 26 ......................

2 ............... black wad .... 80 ......................

4 ............... sand stone .... 75 ......................

3 ............... coal .... 700 ......................

In this account the fixed air was previously extracted from the

limestones by acids, and the heat applied was much less than was

necessary to extract all the air from the bodies employed. Add to this

the known quantities of air which are combined with the calciform ores,

as the ochres of iron, manganese, calamy, grey ore of lead, and some

idea may be formed of the great production of air in volcanic eruptions,

as mentioned in note on Chunda, Vol. II. and of the perpetual

absorptions and evolutions of whole oceans of air from every part of the

earth.

But there would seem to be an officina aeris, a shop where air is both

manufactured and destroyed in the greatest abundance within the polar

circles, as will hereafter be spoken of. Can this be effected by some

yet unknown law of the congelation of aqueous or saline fluids, which

may set at liberty their combined heat, and convert a part both of the

acid and alcali of sea-water into their component airs? Or on the

contrary can the electricity of the northern lights convert inflammable

air and oxygene into water, whilst the great degree of cold at the poles

unites the azote with some other base? Another officina aeris, or

manufacture of air, would seem to exist within the tropics or at the

line, though in a much less quantity than at the poles, owing perhaps to

the action of the sun's light on the moisture suspended in the air, as

will also be spoken of hereafter; but in all other parts of the earth

these absorptions and evolutions of air in a greater or less degree are

perpetually going on in inconceivable abundance; increased probably, and

diminished at different seasons of the year by the approach or

retrocession of the sun's light; future discoveries must elucidate this

part of the subject. To this should be added that as heat and

electricity, and perhaps magnetism, are known to displace air, that it

is not impossible but that the increased or diminished quantities of

these fluids diffused in the atmosphere may increase its weight a well

as its bulk; since their specific attractions or affinities to matter

are very strong, they probably also possess general gravitation to the

earth; a subject which wants further investigation. See Note XXVI.

SOUTH-WEST WINDS.

The velocity of the surface of the earth in moving round its axis

diminishes from the equator to the poles. Whence if a region of air in

this country should be suddenly removed a few degrees towards the north

it must constitute a western wind, because from the velocity it had

previously acquired in this climate by its friction with the earth it

would for a time move quicker than the surface of the country it was

removed to; the contrary must ensue when a region of air is transported

from this country a few degrees southward, because the velocity it had

acquired in this climate would be less than that of the earth's surface

where it was removed to, whence it would appear to constitute a wind

from the east, while in reality the eminent parts of the earth would be

carried against the too slow air. But if this transportation of air from

south to north be performed gradually, the motion of the wind will blow

in the diagonal between south and west. And on the contrary if a region

of air be gradually removed from north to south it would also blow

diagonally between the north and east, from whence we may safely

conclude that all our winds in this country which blow from the north or

east, or any point between them, consist of regions of air brought from

the north; and that all our winds blowing from the south or west, or

from any point between them, are regions of air brought from the south.

It frequently happens during the vernal months that after a north-east

wind has passed over us for several weeks, during which time the

barometer has flood at above 301/2 inches, it becomes suddenly succeeded

by a south-west wind, which also continues several weeks, and the

barometer sinks to nearly 281/2 inches. Now as two inches of the mercury

in the barometer balance one-fifteenth part of the whole atmosphere, an

important question here presents itself, _what is become of all this

air_.

1. This great quantity of air can not be carried in a superior current

towards the line, while the inferior current slows towards the poles,

because then it would equally affect the barometer, which should not

therefore subside from 301/2 inches to 281/2 for six weeks together.

2. It cannot be owing to the air having lost all the moisture which was

previously dissolved in it, because these warm south-west winds are

replete with moisture, and the cold north-east winds, which weigh up the

mercury in the barometer to 31 inches, consist of dry air.

3. It can not be carried over the polar regions and be accumulated on

the meridian, opposite to us in its passage towards the line, as such an

accumulation would equal one-fifteenth of the whole atmosphere, and can

not be supposed to remain in that situation for six weeks together.

4. It can not depend on the existence of tides in the atmosphere, since

it must then correspond to lunar periods. Nor to accumulations of air

from the specific levity of the upper regions of the atmosphere, since

its degree of fluidity must correspond with its tenuity, and

consequently such great mountains of air can not be supposed to exist

for so many weeks together as the south west winds sometimes continue.

5. It remains therefore that there must be at this time a great and

sudden absorption of air in the polar circle by some unknown operation

of nature, and that the south wind runs in to supply the deficiency. Now

as this south wind consists of air brought from a part of the earth's

surface which moves faster than it does in this climate it must have at

the same time a direction from the west by retaining part of the

velocity it had previously acquired. These south-west winds coming from

a warmer country, and becoming colder by their contact with the earth of

this climate, and by their expansion, (so great a part of the

superincumbent atmosphere having vanished,) precipitate their moisture;

and as they continue for several weeks to be absorbed in the polar

circle would seem to receive a perpetual supply from the tropical

regions, especially over the line, as will hereafter be spoken of.

It may sometimes happen that a north-east wind having passed over us may

be bent down and driven back before it has acquired any heat from the

climate, and may thus for a few hours or a day have a south-west

direction, and from its descending from a higher region of the

atmosphere may possess a greater degree of cold than an inferior north

east current of air.

The extreme cold of Jan. 13, 1709, at Paris came on with a gentle south

wind, and was diminished when the wind changed to the north, which is

accounted for by Mr. Homberg from a reflux of air which had been flowing

for some time from the north. Chemical Essays by R. Watson, Vol. V. p.

182.

It may happen that a north-east current may for a day or two pass over

us and produce incessant rain by mixing with the inferior south-west

current; but this as well as the former is of short duration, as its

friction will soon carry the inferior current along with it, and dry or

frosty weather will then succeed.

NORTH-EAST WINDS.

The north-east winds of this country consist of regions of air from the

north, travelling sometimes at the rate of about a mile in two minutes

during the vernal months for several weeks together from the polar

regions toward the south, the mercury in the barometer standing above

30. These winds consist of air greatly cooled by the evaporation of the

ice and snow over which it passes, and as they become warmer by their

contact with the earth of this climate are capable of dissolving more

moisture as they pass along, and are thence attended with frosts in

winter and with dry hot weather in summer.

1. This great quantity of air can not be supplied by superior currents

passing in a contrary direction from south to north, because such

currents must as they arise into the atmosphere a mile or two high

become exposed to so great cold as to occasion them to deposit their

moisture, which would fall through the inferior current upon the earth

in some part of their passage.

2. The whole atmosphere must have increased in quantity, because it

appears by the barometer that there exists one-fifteenth part more air

over us for many weeks together, which could not be thus accumulated by

difference of temperature in respect to heat, or by any aerostatic laws

at present known, or by any lunar influence.

From whence it would appear that immense masses of air were set at

liberty from their combinations with solid bodies, along with a

sufficient quantity of combined heat, within the polar circle, or in

some region to the north of us; and that they thus perpetually increase

the quantity of the atmosphere; and that this is again at certain times

re-absorbed, or enters into new combinations at the line or tropical

regions. By which wonderful contrivance the atmosphere is perpetually

renewed and rendered fit for the support of animal and vegetable life.

SOUTH-EAST WINDS.

The south-east winds of this country consist of air from the north which

had passed by us, or over us, and before it had obtained the velocity of

the earth's surface in this climate had been driven back, owing to a

deficiency of air now commencing at the polar regions. Hence these are

generally dry or freezing winds, and if they succeed north-east winds

should prognosticate a change of wind from north-east to south-west; the

barometer is generally about 30. They are sometimes attended with cloudy

weather, or rain, owing to their having acquired an increased degree of

warmth and moisture before they became retrograde; or to their being

mixed with air from the south.

2. Sometimes these south-east winds consist of a vertical eddy of north-

east air, without any mixture of south-west air; in that case the

barometer continues above 30, and the weather is dry or frosty for four

or five days together.