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PEPLIS, a genus of plants belonging to the hexandria class, and in the natural method ranking under the 17th order, Calycanthema. See BOTANY Index.

PEPLUS, a long robe worn by the women in ancient times, reaching down to the feet, without sleeves, and so very fine, that the shape of the body might be seen through it. The Athenians used much ceremony in making the peplus, and dressing the statue of Minerva with it. Homer makes frequent mention of the peplus of that goddess.

PEPPER, PIPER, in Natural History, an aromatic berry of a hot quality, chiefly used in seasoning. We have three kinds of pepper at present used in the shops, the black, the white, and the long pepper.

Black pepper is the fruit of the piper, and is brought from the Dutch settlements in the East Indies. See PIPER, BOTANY Index.

The common white pepper is factitious, being prepared from the black in the following manner: they steep this in sea-water, exposed to the heat of the sun for several days, till the rind or outer bark loosens; they then take it out, and, when it is half dry, rub it till the rind falls off; then they dry the white fruit, and the remains of the rind blow away like chaff. A great deal of the heat of the pepper is taken off by this process, so that the white kind is more fit for many purposes than the black. However, there is a sort of native white pepper produced on a species of the same plant; which is much better than the factitious, and indeed little inferior to the black.

The long pepper is a dried fruit, of an inch or an inch and a half in length, and about the thickness of a large goose quill: it is of a brownish gray colour, cy. lindrical in figure, and said to be produced on a plant of the same genus.

Pepper is principally used by us in food, to assist digestion: but the people in the East Indies esteem it as a stomachic, and drink a strong infusion of it in water by way of giving them an appetite: they have also a way of making a fiery spirit of fermented fresh pepper with water, which they use for the same pur. poses. They have also a way of preserving the com. mon and long pepper in vinegar, and eating them af terwards at meals.

Jamaica PEPPER, or Pimento. See LAURUS, BoTANY Index.

PEPPER-Mint. See MENTHA, BOTANY and MATERIA MEDICA Index.

PEPPER-Pot. See CAPSICUM, BOTANY Index. PEPPER-Water, a liquor prepared in the following manner, for microscopical observations: Put common black pepper, grossly powdered, into an open vessel so as to cover the bottom of it half an inch thick, and put to it rain or river water till it covers it an inch; shake or stir the whole well together at the first mixing, but never disturb it afterwards; let the vessel be exposed to the air uncovered; and in a few days there will be seen a pellicle or thin skin swimming on the surface of the liquor, presenting several colours.

This is a congeries of multitudes of small animals; VOL. XVI. Part I.

PERAMBULATOR, in surveying, an instrument for measuring distances, called also odometer, pedometer, way-wiser, and surveying-wheel.

It connsists of a wheel AA, fig. 1. two feet seven Plate inches and a half in diameter; consequently half a pole, CCCCIX. or eight feet three inches, in circumference. On one fig. 1. end of the axis is a nut, three quarters of an inch in diameter, and divided into eight teeth; which, upon moving the wheel round, fall into the eight teeth of another nut c, fixed on one end of an iron-rod Q, and thus turn the rod once round in the time the wheel makes one revolution. This rod, lying along a groove in the side of the carriage of the instrument, under the dotted line, has at its other end a square hole, into which is fitted the end b of a small cylinder P. This cylinder is disposed under the dial-plate of a movement, at the end of the carriage B, in such a manner as to be moveable about its axis: its end a is cut into a perpetual screw, which falling into the 32 teeth of a wheel perpendicular thereto, upon driving the instrument forward, that wheel makes a revolution each 16th pole. On the axis of this wheel is a pinion with six teeth, which falling into the teeth of another wheel of 60 teeth, carries it round every 160th pole, or half a mile.

This last wheel, carrying a hand or index round with it over the divisions of a dial-plate, whose outer limb is divided into 160 parts, corresponding to the 160 poles, points out the number of poles passed over. Again, on the axis of this last wheel is a pinion, containing 20 teeth, which falling into the teeth of a third wheel which hath 40 teeth, drives it once round in 320 poles, or a mile. On the axis of this wheel is a pinion of 12 teeth, which, falling into the teeth of a fourth wheel having 72 teeth, drives it once round in 12 miles.

This fourth wheel, carrying another index over the inner limb of the dial-plate, divided into 12 for miles, and each mile subdivided into halves, quarters, and fur. longs, serves to register the revolutions of the other hand, and to keep account of the half miles and miles passed over as far as 12 miles.

The use of this instrument is obvious from its construction. Its proper office is in the surveying of roads R and

Fig. 2.

#Nich

Jour. 15. 81.

Its advantages are its hardiness and expedition; its contrivance is such, that it may be fitted to the wheel of a coach, in which state it performs its office, and measures the road without any trouble at all.

The following is a description of an instrument invented by Mr Edgeworth for the same purpose.

"This odometer," says Mr Edgeworth, "is more simple than any which I have seen, is less liable to be out of order, and may be easily attached to the axletree bed of a post-chaise, gig, or any other carriage. "One turn and a half of a screw is formed round the nave of one of the hinder wheels by a slip of iron three quarters of an inch broad and one-eighth of an inch thick; this is wound round the nave, and fastened to it by screws passing through five or six cocks, which are turned up at right angles on the slip of iron. The helix so formed on the nave of the carriage wheel acts as a worm or screw upon the teeth of the wheel A, fig. 2. upon the arbor of which another screw of brass B is formed, which acts upon the brass wheel C. This wheel C serves also as a dial-plate, and is divided into miles, halves, quarters, and furlongs; the figures indicating the miles are nearly three quarters of an inch long, so as to be quite distinct; they are pointed out by the index D, which is placed as represented in the plate, in such a manner as to be easily seen from the carriage.

"These two brass wheels are mounted by the irons EE upon a block of wood F, eight inches long, two inches thick; and five inches broad. This block may be screwed upon the axle-tree-bed by two strong squareheaded wood screws. If the carriage permits, this block should be fixed obliquely on the axle-tree-bed, so that the dial-plate may be raised up toward the eye of the person looking out from the carriage.

"H is a ratchet wheel attached to the arbor of the wheel A, which, by means of the click I, allows the wheel to be set with a key or handle fitted to the squared end of the arbor at K. L is a long spring screwed on the block; it presses on the wheel A, to prevent it from shaking by the motion of the carriage. A small triangular spring is put under the middle of the dialplate wheel for the same purpose.

"If the wheel of the carriage is exactly five feet three inches in circumference, the brass-toothed wheel which it turns should have twenty teeth, and that which serves as a dial plate should have eighty; it will then count five miles. If the carriage wheel is either larger or smaller, a mile should be carefully measured on a smooth road, and the number of turns which the carriage wheel makes in going this mile may easily be counted by tying a piece of fine packthread to one of the spokes, and letting the wheel, as it moves slowly forward, wind up the packthread on its nave. When the wheel has proceeded a half or a quarter of a mile, unwind the string and count the number of turns which it has made.

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It has been susposed that the ancient Romans were Perambul acquainted with an instrument of this kind. The foundation of this opinion is an expression of Julius Capitolinus in his life of the emperor Pertinax. The words Perception are, Et alia (vehicula), iter metientia, et horas monstrantia." strantia." "Carriages for measuring the length of the road, and marking the time of the journey."

PERCA, the PERCH; a genus of fishes belonging to the order of thoracici. See ICHTHYOLOGY Index.

PERCEPTION, is a word which is so well understood, that it is difficult for the lexicographer to give any explanation of it. It has been called the first and most simple act of the mind by which it is conscious of its own ideas. This definition, however, is improper, as it confounds perception with consciousness; although the objects of the former faculty are things without us, those of the latter the energies of our own minds. Perception is that power or faculty by which, through the medium of the senses, we have the cognizance of objects distinct and apart from ourselves, and learn that we are but a small part in the system of nature. what process the senses give us this information, we have endeavoured to show elsewhere, (see METAPHYSICS, Part I. chap. i.); and we should not again introduce the subject, but to notice a singular opinion of a very able writer, whose work has been given to the public since our article alluded to had issued from the press.

By

Dr Sayers has endeavoured to prove that no man can perceive two objects, or be conscious of two ideas at the same instant. If this be true, not only our theory of time (see METAPHYSICS, Part II. chap. vii.) is grossly absurd, but even memory itself seems to be an imaginary faculty. If a man be not conscious of his present existence, at the very instant when he thinks of a past event, or reviews a series of past transactions, it is difficult, to us indeed impossible, to conceive what idea he can have of time, or what he can mean when he says that he remembers a thing. But let us examine the reasoning by which the ingenious author endeavours to establish his opinion.

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"If we reflect (says he †) upon the surprising velocity + Disquisi with which ideas pass through the mind, and the remark-tions Metaable rapidity with which the mind turns itself, or is di-physical rected from one object of contemplation to another, this rary. might alone give us some suspicion that we may probably be mistaken in supposing ideas to be synchronously perceived. Other arguments may be adduced to strengthen this suspicion. It will be granted, I believe, that the mind, whether immaterial or the result of organization, has certainly a wholeness or unity belonging to it, and that it is either not composed of parts, or that no one of the parts from which it originates is itself mind: in this case, it is difficult to conceive how two ideas should be impressed upon the mind at the same instant for this would be supposing that part of the mind could receive one idea, and part another, at the same time; but if the parts do not perceive singly, this is evidently impossible. If, on the other hand, this self-division of the mind does not take place, then if two ideas are nevertheless to be perceived at the same instant, it would seem that those ideas must be so blended with each other, that neither of them could appear distinct. If we examine the manner in which a complex idea is perceived, we shall find very clearly, that the whole of such an idea is never present to the mind at once. In thinking of a centaur, for instance,

from one mode of operation to another; with which, Perception upon acknowledged principles, it can have nothing in

common.

By far the greater part of our ideas are relicts of visible sensations; and of every thing which we can actually sce at once, we at once contemplate the idea. That we could at once perceive a centaur, if such a being were presented to us, cannot surely be doubted by any one who has ever looked at a man on horseback; and therefore that we can at the same moment contemplate the whole idea of a centaur, is a fact of which consciousness will not permit us to doubt.-It, indeed, we choose to analyze this complex idea into its component parts, it is self evident that the mind must glide from the one to the other, because the very analysis consists in the separation of the parts, of which, if after that process we think of them, we must think in succession: but that we may have at the same instant, either an actual or ideal view of all the parts of the centaur united, is a proposition so evident as to admit of no other proof than an appeal to experience. In contemplating what the author calls the complex idea of gold, it cannot be denied that the ideas of its colour, ductility, hardness, and weight, are never all present to the mind at the same instant: but the reason is obvious. These are not all ideas, in the proper sense of the word, but some of them are ideas, and some notions, acquired by very different processes and very different faculties. Colour is an idea of sensation, immediately suggested through the organ of sight; ductility is a relative notion, acquired by repeated experiments; and gold might be made the object of every sense, without suggesting any such notion. The writer of this article never saw any experiment made on the ductility of gold, and has therefore a very obscure and indistinct notion of that property of the metal; but he is conscious, that he can perceive, at the same instant, the yellow colour and circular figure of a guinea, and have a very distinct, though relative notion, of its hardness.

Perception. stance, can we at the same moment be thinking of the parts of a man and the parts of a horse? Can we not almost detect the gliding of the mind from the one to the other? In contemplating the complex idea of gold, are the ideas of its colour, ductility, hardness, and weight, all present to the mind at the same instant? I think, if we accurately attended to it, we shall find a perceptible time has elapsed before this complex idea has been perfectly formed in our mind: but if all the parts of a complex idea cannot be recalled at the same instant, is it not reasonable to infer that these parts are also singly impressed, and not all originally perceived at the same instant?" This reasoning is plausible, but perhaps not convincing. Surely we have all been conscious of bodily pain or pleasure with our eyes open, and been offended by disagreeable smells at the very instant that we looked at objects beautifully coloured. That our ideas pass through the mind with great velocity, and that the mind can rapidly turn itself from one subject of contemplation to another, are truths which cannot be controverted; but instead of leading us to suppose that two or more objects cannot be synchronously perceived, or two or more ideas synchronously apprehended, they appear to furnish a complete proof of the reverse of all this. For we beg leave to ask how we come to know that ideas pass with velocity through the mind, if we be not all the while conscious of something that is permanent? If we can contemplate but one idea at once, it is plainly impossible that two or more can be compared together; and therefore we cannot possibly say that any particular train has passed through the mind with a degree of velocity greater or less than that which we have usually experienced; nay, we cannot say that we have ever experienced a train of ideas at all, or even been conscious of a single idea, besides the immediate object of present apprehension. That the mind is an individual, we most readily grant; but that it should therefore be incapable of having two ideas synchronously excited in it, is a proposition for which the author has brought no evidence. That it is difficult to conceive how this is done, we acknowledge; but not that it is more difficult than to conceive how a single idea is excited in the mind; for of the mode in which mind and matter mutually operate on each other, we can form no conception. We know that objects make an impression on the organs of sense, that this impression is by the nerves communicated to the brain, and that the agitation of the brain excites sensation in the mind: but in what way it excites sensation we know not; and therefore have no reason to suppose that two or more different agitations may not excite two or more synchronous sensations, as well as one agitation excites one sensation. That the agitation given to the brain operates on the mind, is known by experience; but experience gives us no information repecting the mode of that operation. If the mind be, as our author and we suppose, one individual, it cannot, as mind, be either divisible or extended; and therefore it is certain that the operation in question cannot be, in the proper sense of the word, impression. Hence we have no right to infer, if two objects be perceived at once, either that the idea of the one must be impressed on a part of the mind different from that which receives the impression of the other, or that the two impressions must be so blended with each other, that neither of them could appear distinct; for this would be to reason

We conclude, therefore, that the mind is capable of two or more synchronous perceptions, or synchronous ideas; that during every train which passes through it, it is conscious of its own permanent existence; and that if it were limited to the apprehension of but one idea at once, it could have no remembrance of the past, or anticipation of the future, but would appear to itself, could it make any comparison, to pass away like a flash of lightning.

PERCH, in land measuring, a rod or pole of 165 feet in length, of which 40 in length and 4 in breadth make an acre of ground. But, by the customs of several counties, there is a difference in this measure. In Staffordshire it is 24 feet; and in the forest of Sherwood 25 feet, the foot being there 18 inches long; and in Herefordshire a perch of ditching is 21 feet, the perch of walling 16 feet, and a pole of denshiered ground is 12 feet, &c.

PERCH, a fish. See PERCA, ICHTHYOLOGY Index.

PERCHE, a territory of Orleannois in France, 35 miles long, and 30 broad; bounded on the north by Normandy; on the south, by Maine and Dunois; on the east, by Beauce; and on the west by Maine. It takes its name from a forest, and is pretty fertile. The inhabitants carry on a pretty good trade; and the principal town is Bellesme. R 2 PERCOLATION,

Perche.