from four to eight fides; but the hexagonal columns are as numerous as all the others together.

"On a minute inspection, each pillar is found to be feparable in several joints, whose articulation is neat and compact beyond expreffion; the convex termination of one joint always meeting a concave focket in the next; befides which, the angles of one frequently fhout over those of the other, fo that they are completely locked together, and can rarely be feparated without a fracture of fome of their parts.

"The fides of each column are unequal among themfelves; but the contiguous fides of adjoining columns are always of equal dimensions, fo as to touch in all their parts.

"Though the angles be of various magnitudes, yet the fum of the contiguous angles of adjoining pillars always make up four right ones. Hence there are no void spaces among the bafaites, the furface of the caufeway exhibiting to view a regular and compact pavement of polygon ftones.

"The outfide covering is foft, and of a brown colour, being the earthy parts of the ftone nearly deprived of its metallic principle by the action of the air, and of the marine acid which it receives from the fea.

"The leading features of this whole coaft are the two great promontories of Bengore and Fairhead, which stand at the diftance of eight miles from each other; both formed on a great and extenfive fcale, both abrupt towards the fea, and abundantly exposed to obfervation, and each in its kind exhibiting noble arrangements of the different fpecies of columnar bafaltes.

"The former of thefe lies about feven miles west of Ballycastle, and is made up of a number of capes and bays, the tout ensemble of which forms what the feamen denominate the Head of Bengore.

"The most perfect of thefe capes is called Pleufkin. Its fummit is covered with a thin graffy fod, under which lies the natural rock, having generally an uniform hard furface, fomewhat cracked and fhivered. At the depth of ten or twelve feet from the fummit, this rock begins to affume a columnar tendency, and forms a range of mafly pillars of bafaltes, which stand perpendicular to the horizon, prefenting, in the sharp face of the promontory, the appearance of a magnificent gallery or colonade, upwards of fixty feet in height.

"This colonade is fupported on a folid bafe of coarse, black, irregular rock, near fixty feet thick, ahounding in blebs and airholes; but though comparatively regular, it may be evidently obferved to affect a pe

culiar figure, tending in many places to run into regular forms, refembling the fhooturg of falts, and many other fubftances during a hafty crystallization.

"Under this great bed of ftone stands a fecond range of pillars, between forty and fifty feet in height, lefs grofs, and more tharply defined than those of the upper story, many of them, on a clofe view, emulating even the neatnefs of the columns in the

Giants Caufeway. This lower range is borne on a layer of red ochre ftone, which ferves as a relief to thew it to great advantage.

"Thefe two admirable natural galleries, together with the interjacent mafs of irregu lar rock, form a perpendicular height of 170 feet, from the bafe of which the promontory, covered over with rock and grafs, flopes. down to the fea for the pace of 200 feet more, making in all a mafs of near 400 feet in height, which in beauty and variety of is colouring, in elegance and novelty of arrangement, and in the extraordinary magnificence of its objects, cannot readily be rival-led by any thing of the kind at prefent known.

"At the diftance of eight miles from hence the promontory of Fairhead raifes its lofty fummit more than 400 feet above the fea, forming the eastern termination of Ballycaftle bay. It prefents to view a vast compact mass of rude columnar ftones, the forms of which are extremely grafs, many of them being near 150 feet in length, and the texture fo coarfe, as to resemble black scherle stone, rather than the clofe fine grain of the Giants Caufeway bafaltes. At the bafe of thefe gi gantic columns lies a wild wafte of natural ruins, of an enormous fize, which, in the courfe of fucceffive ages, have been tumbled down from their foundations by storms, or fome more powerful operations of nature, These maffive bodies have fometimes withftood the fhock of their fall, and often lie in groupes and clumps of pillars refembling many of the varieties of artificial ruins, and forming a very novel and ftriking landicape.

"A favage wildness characterizes this great promontory, at the foot of which the ocean rages with uncommon fury. Scarce a fingle mark of vegetation has yet crept over the hard rock to diverfify its colouring, but one uniform greynefs clothes the ftene all around. Upon the whole, it makes a fine contraft with the beautiful capes of Bengore, where the varied brown fhades of the pillars, enlivened by the red and green tints of ochre and grafs, caft a degree of life and chearfulnefs over the different objects.” [To be continued]

The

DOCTOR Mouro fpeaking of the ear of the cetaceous fishes, gives the following account of what he obferved in the diffection of the phocoena, one of that order.

"On each fide of the head there is a round hole, scarcely large enough to admit the head of a fmall pin, which is the beginning of a long meatus auditorius extermus; at the bottom of which we find a concave mem brana tympani. The membrana tympani is conducted to the bottom of the cavity of the tympanum, by a chain of fmall bones, tied together by a reddith-coloured membrane. The innermost piece, analogous to our fapes, has evidently a mufcle connected to it; a large nerve or portio mollis divides the two branches, and then enters the bone at the bottom of the cavity of the tympanum, and following one of the branches of the nerve are led to the cochlea, which is divided into two feale, each containing a reddith coloured tube eafily feparable from the offeous canal which contains it.

"Following the other branch of the nerve, I obferved rat of the femicircular canals; the membrane of which is very thin, and adheres to the bone which cortans it.

"The cavity of the tympanum is remarkably large, and communicates freely with other cavities which are analogous to our front. 1, fphenoidal, and maxillary finutes.

"A tube fimdar to our Euftachian tube, or iter a palato ad aurem, begins towards the lower end of the fittulas thro' which the ani. mal respires, and, contrary to what we ob ferve in men and quadrupeds, enlarges as it runs back towards the cavity of the tympanum, in which it terminates.

"While, therefore, the e animals float on the furface of the ocean, impresion is made on the feveral parts of their ear in the fame manner as in man.”

From the remarkable difference of the fize of the caverns which communicate with the cavity of the tympanum, the Doctor is ted to confider, whether the effect of the found upon the ear be encreased by that circumftance? or whether the chief ufe of theis caverns be to render the head specifically lighter, and like fwimming bladders to make it rife more readily to the furface of the fea? Our author next proceeds to defcribe the ear in amphibious animals, particularly the fea tortoife or turtle, previous to his giving of the structure of that organ in the Nantes Pinnati and Pifces of Linnaus. But for thefe * mult refer to the work felf, more ei

pecially as the reader is confiderably affifted by references to the annexed plates, and go on to the Doctor's account of fome experiments made by him in 1780, on hearing in water, the better to be able to judge of the effect of found upon the ears.

For this purpose he employed two bells, the found of which he was used to; one of them a final tea-table bell, the other much larger and thicker, fo that the found of it could be very well heard at the distance of a quarter of a mile.

When thefe were plunged under water and rung, he obferved that the found of them was very fenfibly graver; but ftill the ringing tremor of both was very diftinguishable. On performing an accurate experiment, the tea-table bell was found in air the highest G of harpsichord; but in water it founded a fith falfe lower, or it founded the C fharp under the G.

He next plunged his head under the water while he rung the bell in the air, and heard the found of it diftinctly. As the tone of the bell is louder and more acute in the air than in the water, its found is neceflarily better heard when the head of the perfon making the experiment is under the water and the bell above it, than when the bell is rung under the water while the head is above it.

The Doctor next plunged his whole body with the bells, holding their handles in his hands, under the water, and then rung them, and was furprifed with the loudnefs and diftina nefs of their founds, and could readily diftinguish their different tones.

In like manner, when plunged under the water, he truck two ftones held in his hands against each other, and was furprised with the tho k communicated to the ears.

He

This experiment confims Dr. Franklin's opinion, "That water will convey found farther and more readily than air. thinks he bas heard a fmart stroke of two ftones together under water, his ear being alfo under water in the fame river, near a mile: how much farther it may be heard he knows not, but fuppoíes a great deal farther, because the found did not feem faint, as if at a diftance, like dittant founds thro' the air, but imart and strong, as if prefent juft at the ear "

Our author, afterwards, by means of a ftring tied to the handle of the largest bell, and to an inflated bladder, infpeaded that bell in a very deep pool, fix feet under the

furface of the water, and took hold of a cord twelve yards long, which he had previoufly tied to the handle. He then plunged under the water and pulled the cord, and found the found was inftantly conveyed to his ears.

He in the last place thought of trying an experiment, to determine whether air or water conveyed found quickest: but there being no lake near Edinburgh above 800 feet broad, he found it impoffible, independently of the difficulty of constructing a proper apparatus, to perform the experiment in a fatisfactory and decifive way. He, however, made the following trial. He charged three English pint bottles each with about ten ounces of gunpowder. He then inferted a tin tube four feet in length into each bottle, and prevented the water from getting into the bottle by wrapping a piece of wet bladder round the neck of it and the neck of the tube which entered into it, and tying the tube and neck of the bottle to each other.

After filling the tube with gunpowder, he fixed to the top of it a piece of match paper, and into the match paper, just over the top of the tube, he put two ounces of gunpowder.

He then funk the bottle near the fide of a lake to the depth of about two feet, and went into the water at the greatest diftance poffible, which was about 800 feet, and laid himself on his back in the water, with his ears under its furface, and nofe and eyes above it. The match was then set fire to by another perfon; and as it was midnight, he faw the flash of the gunpowder contained within the match, and foon after heard the noife of the explosion of the gunpowder within the bottle. But he found it impoffible in this way to determine the velocity of the found with accuracy, as the gunpowder in the bottle was not fet fire to through the tube fo inftantaneously as was expected.

For want of being provided with a proper apparatus, the piece of water not being of fufficient extent, and the experiment too feldom repeated, the only conclufion the profeffor could draw, was, that after the bottle burst he heard one, but did not hear two explosions; fo that the water feemed to convey the found nearly in the fame time as the atmosphere.

The Doctor proposes the following experiment as most likely to be fatisfactory. "To fufpend under water, in a broad lake, a large and loud founding bell, such as is ufed in church fteeples, and for one perfon to strike this with an iron hammer, between the handle of which and the trigger of a mufket, or cannon fired with a lock, a rope was ftretched; while another person was fta

tioned at the distance of a mile or more, with one or both ears under water."

By this means, as two very different founds would be produced at the fame inftant, the one in air and the other in water, it might be ́obferved which of them ftruck the ear fooneft. Befides this, the flafh fhewing the exact time at which the bell was ftruck, the velocity of the found in the water might be accurately determined.

To this experiment, however, one forcible objection occurs in our opinion, which feems to have efcaped the Doctor's attention, viz. that the found of the gun has to pafs not only through the medium of air, but alfo through that of water, before it can reach the ear fupposed to be placed under water, whereas the found of the bell will pafs immediately thro' the fame homogeneous medium directly to the ear; which difference, we apprehend, will prevent the velocity of the different founds from being fo accurately afcertained as might be wifhed.

The tenth chapter treats of the several ways in which the tremor of fonorous bodies is communicated in the different claffes of animals to the nerves fpread on the bottom of the ear.

Speaking of the eyes of fishes, in the next chapter, the Doctor fays,

"In all fishes, 10 far as I have observed, the pigment on the inner fide of the choroid coat is, as in land-animals which feek their food in the night-time, of a bright colour at the bottom of the eye; perhaps because the light ftrikes the bottom of the eye with lefs force than in the land animals, many of its rays being intercepted by the water. To account however for the different colour of this pigment, in the different genera of animals, feems to be a matter of much difficulty: nay, it may be a queftion, whether the chief ufes of the choroid coat in any animal have been clearly afcertained; or whether we certainly know in what manner the choroid coat is fubfervient to the retina. Perhaps attention to the powers of the eyes in two animals which are mere varieties of the fame fpecies, may ferve to throw farther light on this curious fubject; I mean the brown and the white rabbit for in the former the choroid is even covered with a dark pigment; whereas, in the latter, though the choroid coat is as much compofed of veffels as in other animals, I have found that the black paint, tapetum, or inner layer of the choroid, is altogether wanting: and hence the colour of the red blood circulating in the veffels of the choroid, is feen when when we look into the eye, or makes their eyes appear red."

:

The Doctor proceeds to remark, that the humours of the eyes of fishes are proportion

ally