not be imitated or difplayed by the painter. Exquifite fcenery, without being picturefque, may be dif tinguished both for beauty and grandeur. Or fhall we fay, as I have heard afferted by fome fafhionable connoiffeurs, that nothing in external nature, no combination whatever of water, trees, and ver dure, can be accounted a beautiful object, unless it can be transferred to the canvas? Contrary to this, it may at least be doubted, whether many delightful paffages, if I may fo exprefs myself, both at the Leafowes and among the lakes in Cumberland, though gazed at with tendernefs, or contemplated with admiration, would not baffle all the power of the pencil. Though poetry ought to be like painting, yet the naxim or rule, like many other fuch rules and maxims, is not to be received without due limitation.

"It is therefore the duty of the painter, who by his art would illuftrate that of the poet, to confider in every particular inftance, whether the defcription or image be really pictarefque. I am loth to blame where there is much to commend, and where the artift poffeffes high and deferved reputation. But will it not be admitted that the picture by Reynolds, which reprefents the death of cardinal Beaufort as defcribed by Shakespeare, is liable to the cenfure of injudicious felection in the choice of a fubject? Or is it poffible for any colouring or delineation to convey the horror of the fituation fo impreffively as in the words of the poet ?

Sal Disturb him not, let him

pafs peaceably. King. Peace to his foul, if God's good pleasure be !-Lord Cardinal, if thou think'ft on Heaven's blifs,

He dies, and makes no fign :-0

God, forgive him!

"The fubject is entitled to more particular confideration. — Certain difpofitions of mind produce great effects on the body; agitate the whole frame; imprefs or distort the features. Others again, more latent or more referved, fupprefs their external fymptoms, scorn or reject, or are not fo capable of external difplay; and occafion no remark able, or no inmediate change in limb, colour, or feature. Such peculiar feelings and affections, averle to render themselves vifible, are not fit fubjects for that art which affects the mind, by prefenting to the eye the refemblant figns of its objects. Defpair is of this number: fuch utter

defpair as that of cardinal Beaufort. It will not complain, for it expects no redrefs; it will not lament, for it defires no fympathy; brooding upon its hopeless affiction, it neither weeps, nor fpeaks, 'nor

6

gives any fign.' But, in the pic. ture under review, the painter reprefents the chief character in violent and extreme agitation. Nor is even that agitation, if we allow defpair to difplay agitation, of a kind fufficiently appropriated. Is it the fullen anguith, the fuppruled agony, the horrid gloom, the tortured foul of defpair? No: it is the agi tation of bodily pain. The poor abje&t fufferer gnashes his teeth, and writhes his body, as under the tor ment of corporal fuffering. The anguish is not that of the mind.→ No doubt, at a preceding moment, before his defpondency was com pletely ratified, the poet reprefents him as in great perturbation; but the affiction is from the pangs death.

do make him grin..

« But

"But after his defpair receives full confirmation from the heartfearching fpeech of Henry, his feelings are feared with horror, and his agony will give no fign.' For the moment of the picture is not when Beaufort is faid to be grinning with mortal anguifh; but the more awful moment, when having heard the request of Henry, he finks, of confequence, into the deepest defpondency. Before that it would have been no other than the picture of a man, of any man whatever, expiring with bodily pain. If indeed the picture is to exprefs any thing peculiar or characteristic, it must be defpair formerly excited, but now ratified and confirmed by the fpeech of Henry.

King. Lord Cardinal, if thou

think'ft on Heaven's blifs, Hold up thy hand, make figual of thy hope.

He dies, and makes no fign:-O

God, forgive him!

"In fhort, the paffage, highly fublime and affecting, as it must be acknowledged, is more poetical than picturefque: and the artift has wafted, on an ill-chofen fubject, his powers, rather of execution in this inftance, than of invention. Surely we fee no masterly invention in the preternatural being placed behind or befide the cardinal; for though the poet has faid, in the character of Henry, that a 'bufy meddling fiend ⚫ was laying fiege to his foul;' yet as the fpeaker did not actually fee the fiend, there was no occafion for introducing him, like the devil in a puppet-how, by the fide of his bed. Nor is there much invention in the ftale artifice of concealing the countenance of the king, because his

feelings could not be painted. In fact, the affectionate aftonishment and pious horror of Henry were fitter for delineation, than the filent, fullen, and uncommunicative despair of Beaufort.

"The rage of delineating to the eye all that is reckoned fine in writ ing may be illuftrated alfo, in the performances of other able and famous artifts. In Gray's Ode on the Spring, we have the following allegorical defcription:

Lo! where the rofy-bofom'd hours,
Fair Venus' train, appear,
Difclofe the long expecting flowers,
And wake the purple year.

"The hours accordingly, adorn. ed with roses difpofed as the poet defcribes them, are reprefented on canvafs, as a company of jolly damfels, twitching or pulling another very beautiful and buxom female, who is reprefented as fleeping on a bank, and clothed with a purple petticoat. Seeing fuch things, it is impoffible not to think of Quarles's or Hugo's Emblems. The thought, who fhall deliver me from this body of fin and death?' is prefented to the eye, in one of them, by the figure of a man enclosed within the ribs of a monstrous and hideous fkeleton. In truth, the inventor of the prints in fome editions of the Pilgrim's Progrefs (where, among others, Chriftian is reprefented as trudging along like a pedlar, with a burden on his back) is entitled to the merit of priority in the extrava gance of fuch inventions; for let it be remembered, that it is only againft extravagancies and mifapplications, and not against the invention itself, that I have ventured to remonftrate."

PHILOSO

"TH HAT heat paffes more freely through fome bodies than through others, is a fact well known; but the caufe of this difference in the conducting powers of bodies, with refpect to heat, has not yet been discovered.

"The utility of giving a wooden handle to a tea-pot or coffee-pot of metal, or of covering its metallic handle with leather, or with wood, is well known: but the difference in the conducting powers of various bodies with regard to heat, may be fhown by a great number of very fimple experiments;-fuch as are in the power of every one to make at all times and in all places, and almost without either trouble or expence.

"If an iron nail and a pin of wood, of the fame form and dimenfions, be held fucceffively in the flame of a candle, the difference in the conducting powers of the metal and of wood will manifest itself in a manner in which there will be no room left for doubt. As foon as the end of the nail, which is expofed in the flame of the candle, begins to be heated, the other end of it

will grow fo hot as to render it im poffible to hold it in the hand without being burnt; but the wood may be held any length of time in the fame fituation without the leaft inconvenience; and even after it has taken fire, it may be held till it is almost entirely coufumed; for the uninflained wood will not grow hot, and, till the flame actually comes in contact with the fingers, they will not be burnt. If a finall flip or tube of glafs be held in the flame of the candle in the fame manner, the end of the glafs by which it is held will be found to be more heated than the wood, but incomparably lefs fp than the pin or nail of metal;

and among all the various bodies that can be tried in this manner, no two of them will be found to give a paffage to heat through their fubftances with exactly the fame degree of facility.

"To confine heat is nothing more than to prevent its efcape out of the hot body in which it exifts, and in which it is required to be re tained; and this can only be done by furrounding the hot body by fome covering composed of a sub

ftanco

ftance through which heat cannot país, or through which it paffes with great difficulty. If a covering could be found perfectly impervious to heat, there is reafon to believe that a hot body, completely furrounded by it, would remain hot for ever; but we are acquainted with no fuch fubftance; nor is it probable that ány fuch exists.

"Those bodies in which heat paffes freely or rapidly, are called conductors of heat; thofe in which it makes its way with great difficulty, or very flowly, non-conductors, or bad conductors of heat. The epithets, good, bad, indifferent, excellent, &c. are applied indifferently to conductors and to non-conductors. A good conductor, for instance, is one in which heat paffes very freely; a good nonconductor is one in which it paffes with great difficulty; and an indifferent conductor may likewife be called, without any impropriety, an indifferent non-conductor.

"Those bodies which are the worst conductors, or rather the best non-conductors of heat, are beft adapted for forming coverings for confining heat.

"All the metals are remarkably good conductors of heat:-wood, and in general all light, dry, and fpungy bodies, are non-conductors: giafs, though a very hard and compact body, is a non-conductor. Mercury, water, and liquids of all kinds, are conductors; but air, and in general all elaftic fluids, fteam not even excepted, are non-conductors. "Some experiments which I have lately made, and which have not yet been published, have induced me to fufpect, that water, mercury, and all other non-elaftic fluids, do not permit heat to pafs through them from particle to particle, as it undoubtedly paffes through folid bodies, but that their apparent con

ducting powers depend effentially upon the extreme mobility of their parts; in fhort, that they rather tranfport heat than allow it a pasfage. But I will not anticipate a fubject which I propofe to treat more fully at fome future period.

"The conducting power of any folid body in one folid mafs, is much greater than that of the fame body reduced to a powder, or divided into many fmalier pieces: an irou bar, or an iron plate, for instance, is a much better conductor of heat than iron filings; and faw-duft is a better non-conductor than wood. Dry wood-afhes is a better nonconductor than either; and very dry charcoal reduced to a fine powder is one of the beft non-conductors known; and as charcoal is. perfectly incombustible when confined in a fpace where fresh air can have no accefs, it is admirably well calculated for forming a barrier for confining heat, where the heat to be confined is intenfe.

"But among all the various fubftances of which coverings may be formed for confining heat, none can be employed with greater advantage than common atmospheric air. It is what nature employs for that purpofe; and we cannot do better than to imitate her.

"The warmth of the wool and fur of beafts, and of the feathers of birds, is undoubtedly owing to the air in their interftices; which air, being strongly attracted by thefe fubftances, is confined, and forms a barrier which not only prevents the cold winds from approaching the body of the animal, but which oppofes an almoft infurmountable obftacle to the efcape of the heat of the animal into the atmosphere. And in the fame manner the air in fnow ferves to preferve the heat of the earth in winter. The warmth

of

may be fhewn to depend on the fame caufe; and were this circumftance more generally known, and more attended to, very important improvements in the management of heat could not fail to refult from it. A great part of our lives is fpent in guarding ourselves against the extremes of heat and of cold, and in operations in which the ufe of fire is indifpenfable; and yet how little progress has been made in that moft ufeful and most important of the arts, the management of heat!

"Double windows have been in ufe many years in moft of the northern parts of Europe, and their great utility, in rendering the houfes furnished with them warm and comfortable in winter, is univerfally ac knowledged, but I have never heard that any body has thought of employing them in hot countries to keep their apartments cool in fummer; yet how cafy and natural is this application of fo fimple and ufeful an invention!-If a double window can prevent the heat which is in a room from palling out of it, one would imagine it could require no great effort of genius to difcover that it would be equally efficacious for preventing the heat without from coming in. But natural as this conclufion may appear, I believe it has never yet occurred to any body; at least, I am quite certain that I have never feen a double window either in Italy, or in any other hot country I have had occaLion to visit.

"But the utility of double win dows and double walls, in hot as well as in cold countries, is a matter of so much importance, that I fhall take occafion to treat it more fully in another place. In the mean time, I fall only obferve here, that

tween the two windows, and not the double giafs plates, tha: renders the paffage of heat through them fo difficult. Were it owing to the in created thickness of the glass, a fingle pane of glass twice as thick would anfwer the fame purpose but the increased thickness of the glafs of which a window is formed, is not found to have any fenfible effect in rendering a room warmer.

"But air is not only a non-condoctor of heat, but its non-conduct ing power may be greatly increased. To be able to form a juft idea of the manner in which air may be rendered a worse conductor of heat, or, which is the fame thing, a better non-conductor of it, than it is in its natural unconfined slate, it will be neceffary to confider the manner in which heat paffes through air. Now it appears, from the refult of a num• ber of experiments which I made with a view to the investigation of this fubject, and which are published in a paper read before the Royal Society, that though the particles of air, each particle for itself, can receive heat from other bodies, or communicate it to them, yet there is no communication of heat be tween one particle of air and ano. ther particle of air. And from hence it follows, that though air may, and certainly does, carry off heat, and tranfport it from one place, or from one body to another, yet a mafs of air in a quiefcent ftate, or with all its particles at reft, could it remain in this ftate,would be totally impervious to heat; or fuch a mass of air would be a perfect non-conductor.

"Now if heat passes in a mass of air merely in confequence of the motion it occafions in that air,-if it is tranfported,—not fuffered to pafs,-in that cafe, it is clear that

what