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it two fmall claws, about one-fixth of an inch in length. If the hair, and mucus entangled in it, be taken away, this extremity of the hell becomes concave, is of a pink colour, and the two claws rising out from its middle part have each three fhort branches, not unlike the horns of a deer. The body of this fhell has a foft cartilaginous covering, with an irregular but polifhed furface: on this the cones reft in their collapsed flate, in which ftate the whole of the fhell is drawn into the cavity of the brain-ftone, excepting the flattened end with the two claws.

"Before the cones there is a thin membrane, which appears to be of the fame length with the fhell juft defcribed. In the collapfed state it lies between the cones and the fhell in which the animal is inclofed; but when the tentacula are thrown out, it is alfo protruded.

The hell of this animal is a tube, which is very thin, and adapt ed to its body: the internal furface is fmooth, and of a pinkifh white colour: its outer furface is covered by the brain-ftone in which it is in closed, and the turnings and wind ings which it makes are very nume rous. The end of the fhell, which opens externally, rifes above the furface of the stone on one fide half an inch in height, for about half the circumference of the aperture, bending a little forwards over it, and becoming narrower and narrower as it goes up, terminating at laft in a point just over the centre of the opening of the hell on the other fide it forms a round margin to the furface of the brain-ftone, This part of the fhell is much thick. er and stronger than that part which is inclofed in the brain-tone: its outer furface is of a darkish brown colour; its inner of a pinkish white.

"The animal, when at reft, is wholly concealed in its fhell; but when it feeks for food, the move. able thell is puthed flowly out with the cones and their membranes in a collapfed ftate; and when the whole is expofed, the moveable fhell falls a little back, and the membrane round each of the cones is expanded, the tentacula at the bafes of the cones having just room enough to move without touching one an other. The thin membrane which lays between the cones and the inclofing fhell is protruded in the form of a fold, and lies over the external fhell which projects from the brain-ftone.

"The membranes have a flow fpiral motion, which continues dur ing the whole time of their being expanded; and the tentacula upon their edges are in conftant action. The motion of the membrane of the one cone feems to be a little different from that of the other, and they change from the one kind of motion to the other alternately, a variation in the colour of the mem brane at the fame time taking place, either becoming a fhade lighter or darker; and this change in the colour, while the whole is in motion, produces a pleafing effect, and is moft ftriking when the fun is very bright. The membranes, however, at fome particular times appear to be of the fame colour.

"While the membranes are in motion, a little mucus is often fe parated from the tentacula at the point of the cone. Upon the least motion being given to the water, the cones are immediately and very fuddenly drawn in.

"This apparatus for catching food is the most delicate and complicated that I have feen; but I shall not trouble you with any conjectures upon what that food may be, as

about two yards from the bottom of the well, and being furrounded with well rammed clay, the new water afcended in a small stream through the wooden pipe.

"Our next operation was to build a wall of clay against the moraffy fides of the well, with a wall of well-bricks internally, up to the top of it. This completely stopped out every drop of the old water; and, on taking out the plug which had been put in the wooden pipe, the new water in two or three days rofe up to the top, and flowed over the edges of the well.

"Afterwards, to gratify my cu riofity in feeing how high the new fpring would rife, and for the agree able purpose of procuring the water at all times quite cold and fresh, I directed a pipe of lead, about eight yards long, and three-quarters of an inch diameter, to be introduced through the wooden pipe defcribed above, into the ftratum of marl at the bottom of the well, fo as to stand about three feet above the furface of the ground. Near the bottom of this leaden pipe was fewed, between two leaden rings or flanches, an inverted cone of ftiff leather, into which fome wool was stuffed to stretch it out, so that, after having paffed through the wooden pipe, it might completely fill up the perforation of the clay. Another leaden ring or flanch was foldered round the leaden pipe, about two yards below the furface of the ground, which, with fome doubles of flannel placed under it, was nailed on the top of the wooden pipe, by which means the water was perfectly precluded from rifing between the wooden and the leaden pipes.

"This being accomplished, the bottom of the well remained quite dry, and the new water quickly

rofe about a foot above the top of the well in the leaden pipe; and, on bending the mouth of this pipe to the level of the furface of the ground, about two hogfheads of water flowed from it in twenty-four hours, which had fimilar properties with the water of St. A'kmund's well, as on comparison both thefe waters curdled a folution of soap in spirit of wine, and abounded with calcareous earth, which was copiously precipitated by a folution of fixed alkali; but the new water was found to poffefs a greater abun dance of it, together with numerous fmall bubbles of aerial acid or calcareous gas.

"The new water has now flow. ed about twelve months, and, as far as I can judge, is already in creafed to almoft double the quantity in a given time; and from the rude experiments I made, I think it is now lefs replete with calcareous earth, approaching gradually to an exact correfpondence with St. Alkmund's well, as it probably has its origin between the fame itrata of earth.

"As many mountains bear in contestable marks of their having been forcibly raised up by fome power beneath them; and other mountains, and even iflands, have been lifted up by fubterraneous fires in our own times, we may fafely reafon on the fame fuppofition in refpect to all other great elevations of ground. Proofs of these circumftances are to be seen on both fides of this part of the country. Whoever will infpect, with the eye of a philofopher, the lime-mountain at Breedon, on the edge of Leicestershire, will not hefitate a moment in pronouncing, that it has been forcibly elevated by fome power beneath it; for it is of a conical form, with the apex

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the impreffion on the leaf was made in fuch a way as to affect the petiolus, the motion took place. When, therefore, I wanted to confine the motion to a fingle leaf, I either touched it fo as only to affect its own petiolus, or, without meddling with the leaf, touched the petiolus with any small-pointed body, as a pin or knife.

By compreffing the univerfal petiolus near the place where a partial one comes out, the leaf moves in a few seconds, in the fame manner as if you had touched the partial petiolus.

"Whether the impreffion be made by puncture, percuffion, or compreffion, the motion does not instantly follow: generally feveral feconds intervene, and then it is not by a jirk, but regular and gradual. Afterwards, when the leaves return to their former fituation, which is commonly in a quarter of an hour or lefs, it is in fo flow a manner as to be almoft imperceptible.

"On sticking a pin into the univerfal petiolus at its origin, the leaf next it, which is always on the outer fide, moves firft; then the fift leaf on the opposite fide, next the second leaf on the outer, and fo on. But this regular progreffion feldom continues through out; for the leaves on the outer fide of the pinna feem to be affected both more quickly, and with more energy, than thofe of the inner, fo that the fourth leaf on the outer fide frequently moves as foon as the third on the inner; and fometimes a leaf, efpecially on the inner fide, does not move at all, whit thofe above and below it are affected in their proper time. Sometimes the leaves at the extremity of the etiolus move fooner than fe

veral others which were nearer the place where the pin was put in.

"On making a compreffion with a pair of pincers on the univerfal petiolus, between any two pair of leaves, thofe above the compreffed part, or nearer the extremity of the petiolus, move fooner than thofe under it, or nearer the origin; and frequently the motion will extend upwards to the extreme leaf, whilft below it perhaps does not go farther than the nearest pair.

"If the leaves happen to be blown by the wind against one another, or against the branches, they are frequently put in motion; but when a branch is moved gently, either by the hand or the wind, without ftriking against any thing, no motion of the leaves takes place.

"When left to themfelves in the day-time, fhaded from the fun, wind, rain, or any disturbing caufe, the appearance of the leaves is dif ferent from that of other pinnated plants. In the last a great uniformity fubfifts in the refpective pofition of the leaves on the pinna; but here fome will be feen on the horizontal plane, fome raised above it, and others fallen under it; and in an hour or fo, without any or der or regularity, which I could obferve, all thefe will have changed their respective positions. I have feen a leaf, which was high up, fall down; this it did as quickly as if a strong impreffion had been made on it, but there was no caufe to be perceived.

"Cutting the bark of the branch down to the wood, and even feparating it about the fpace of half an inch all round, fo as to ftop all communication by the veffels of the bark, does not for the first day af fect the leaves, either in their pofition or their aptitude for motion.

have also been informed, that in the town of Richmond, in Surrey, and at Infhip near Prefton, in Lancafhire, it is ufual to bore for water through a lower ftratum of earth to a certain depth; and that when it is found at both thofe places, it rifes so high as to overflow the fur face of the well: all thefe facts contribute to establishi the theory

above mentioned. And there is reafon to conclude, that if fimilar experiments were made, artificial fprings, rifing above ground, might in many places be thus produced at fmall expence, both for the common purposes of life, and for the great improvement of lands by oc calionally watering them."

EXTRACT from the Rev. Mr. MORGAN'S OBSERVATIONS and EXPERIMENTS on the LIGHT of BODIES in a STATE of COMBUSTION.

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[From the fame Publication.]

HE difcuffion which I now wish to lay before the Royal Society is nothing more than a feries of facts, and of conclufions which feem to flow from thofe facts, and from an attention to the following data.

I. That light is a body, and, like all other bodies, fubject to the laws of attraction.

"II. That light is an heterogeneous body, and that the fame attraftive power operates with different degrees of force on its different parts.

III. That the light which efcapes from combustibles when decompofed by heat, or by any other means, was, previoufly to its efcape, a component part of thofe fubftances.

"It is an obvious conclufion from these data, that when the attractive force, by which the feveral rays of light are attached to a body, is weakened, fome of those rays will efcape fooner than others. Those which are united with the leaft degree of power will efcape fir, and thofe which adhere to it moft strongly will (if I may be allowed

the expreffion) be the last to quit their basis. We may here have recourfe to a familiar fact, which is analogous to this, and will illustrate it.

If a mixture, confifting of equal parts of water, of fpirits of wine, and of other more fixed bodies, be placed over a fire; the first influence of that heat, to which all the ingredients are alike expofed, will carry off the fpirits of wine only. The next will carry off the fpirits of wine blended with particles of water. A till greater degree of heat will blend with the vapour which efcapes a part of the more fixed bodies, till at length what evaporates will be a mixture of all the ingredients which were at first expofed to the fire. In like manner, when the furface of a combustible is in a state of decompofition, thofe parts which are the leaft fixed, or which are united to it with the leaft force, will be feparated first. Amongst these the indigo rays of light will make the earliest appearance. By increafing the heat we fhall mix the violet with the indigo. By increasing it ftill more we fhall add the blue and

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the

[164] EXPERIMENTS on the LOSS of WEIGHT in BODIES,

in fhewing the lofs of weight In ice on being heated.

"The beam I made ufe of was fo adjusted as that, with a weight between four and five ounces in each scale, ' part of a grain made a difference of one divifion on the index. It was placed in a room, the heat of which was 37 degrees of Fahrenheit's thermometer, between one and two in the afternoon, and left till the whole apparatus and the brafs weights acquired the fame temperature.

for about a minute, I found it be gan to lofe weight, on which I immediately took it out, and placed it at a distance from the beam. I alfo immediately plunged a ther mometer in the freezing mixture, and found the temperature 10 degrees; and on putting the ball of the thermometer in the hollow at the bottom of the glafs veffel, it thewed 12 degrees. I left the whole for half an hour, and found the thermometer, applied to the hollow of the glafs, at 32°. Every "A glass globe, of three inches thing now being at the fame temdiameter nearly, with an indenta- perature, I weighed the glass contion at the bottom, and a tube at taining the ice, after wiping it carethe top, weighing about 451 grains, fully, and found it had loft and had about 1700 grains of New- five divifions; fo that it weighed river water poured into it, and was, all but one divifion, more than hermetically fealed, fo that the when the water was fluid. whole, when perfectly clean, weighed 2150 of a grain exactly; the heat being brought to 32 degrees, by placing it in a cooling mixture of falt and ice till it just began to freeze, and fhaking the whole together.

"After it was weighed it was again put into the freezing mixture, and let ftand for about 20 minutes; it was then taken out of the mixture part of the water was found to be frozen; and it was carefully wiped, first with a dry linen cloth, and afterwards with dry washed leather; and on putting it into the scale it was found to have gained about the part of a grain. This was repeated five times: at each time more of the water was frozen, and more weight gained. In the mean time the heat of the room and apparatus had funk to the freezing point.

"When the whole was frozen, it was carefully wiped and weighed, and found to have gained of a grain and four divifions of the index. Upon standing in the fcale

"I now melted the ice, excepting a very finall quantity, and left the glafs veffel expofed to the air in the temperature of 32 degrees for a quarter of an hour: the little bit of ice continued nearly the fame. I now weighed it, after carefully wiping the glafs, and found it heavier than the water was at first, one divifion of the beam. Laftly, I took out the weights, and found the beam exactly ba lanced as before the experiment.

"The acquifition of weight found on water's being converted into ice, may arife from an increase of the attraction of gravitation of the matter of the water; or from fome fubftance imbibed through the glafs, which is neceffary to render the water folid.

"Which of these pofitions is true may be determined by forming a pendulum of water, and another of ice, of the fame length, and in every other refpect fimilar, and making them fwing equal arcs. If they mark equal times, then certainly there is fome matter added

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