through a portal, and going down with great timidity into a darker region, where he is received by a beautiful female, who stretches forth her hand to help him; between her knees is a large and playful serpent. She sits with her feet towards an aged figure, having one foot sunk into the earth, and the other raised on a column with his chin resting on his hand. Above the female figure is a Cupid preceding the first figure, and beckoning him to advance. This first figure holds a cloak or garment, which he seems anxious to bring with him, but which adheres to the side of the portal through which he has passed. In this compartment there are two trees, one of which bends over the female figure, and the other over the aged one. On the bottom of the vase there is another figure, on a larger scale than the one we have already mentioned, but not so well finished nor so elevated. This figure points with its finger to its mouth. The dress appears to be curious and cumbersome, and above there is the foliage of a tree. On the head of the figure there is a Phrygian cap; it is not easy to say whether this figure be male or female. On the handles of the vase are represented two aged heads, with the ears of a quadruped, and from the middle of the forehead rises a kind of tree without leaves; these figures are, in all probability, mere ornaments, and have no connection with the rest of the figures, or the story represented on the vase.

PORTLANDIA, in botany, so named in honour of the Duchess of Portland, a genus of the Pentandria Monogynia class and order. Natural order of Rubiacea, Jussieu. Essential character: corolla club, funnel-shaped; anthers longitudinal; capsule five-cornered, obtuse, two-celled, two-valved, many-seed, crowned with a five-leaved calyx. There are four species.

PORTMANTEAU, a cloak bag of cloth, leather, &c. in which the cloak, linen, and other habiliments of travellers are disposed and laid on the horse's crupper. The same name is also given to a piece of joiner's work fastened to the wall in a wardrobe, armory, &c. proper for the hanging on of cloaks, hats, &c.

PORTRAIT, POURTRAIT, or POURTRAITURE, in painting, the representation of a person, and especially of a face, done from the life. In this sense we use the term portrait-painting, in contradistinction to history-painting, where a resemblance of person is usually disregard

ed. Portraits, when as large as the life, are usually painted in oil-colours; sometimes they are painted in miniature with water colours, crayons, pastils, &c. See PAINTING.

PORTULACA, in botany, purslane, a genus of the Dodecandria Monogynia class and order. Natural order of Succulentæ. Portulaceæ, Jussieu. Essential character: calyx bifid; corolla five-petalled; capsule one-celled, cut round, or threevalved. There are twelve species; of which P. oleracea, garden purslane, is an annual herbaceous plant, with a round, procumbent, succulent stem; diffused branches, often throwing out fibres at the joints; leaves wedge-shaped, oblong, blunt, fleshy, sessile, clustered, especially at the ends of the branches: flowers sessile, corollas yellow, spreading; it is a native of both Indies, China, and Japan.

PORTULACARIA, in botany, a genus of the Pentandria Trigynia class and order. Essential character: calyx two-leaved; petals five; seed one, three-sided and winged. There is but one species, viz. P. afra, a native of Africa.

POSITION, or the rule of false PosiTION, otherwise called the rule of FALSEHOOD, in arithmetic, is a rule so called, because, in calculating on several false numbers taken at random, as if they were the true ones, and from the differences found therein, the number sought is determined. This rule is either single or double. Single position is when there happens in the proposition some partition of numbers into parts proportional, in which case the question may be resolved, at one operation, by this rule. Imagine a number at pleasure, and work therewith according to the tenor of the question, as if it were the true number: and what proportion there is between the false conclusion and the false proportion, such proportion the given number has to the number sought. Therefore the number found by argumentation shall be the first term of the rule of three; the second number supposed, the second term; and the given number, the third. Or the result is to be regulated by this proportion, viz. As the total arising from the error to the true total, so is the supposed part to the true one. Example, A, B, and C, designing to buy a quantity of lead to the value of 140l. agree that B shall pay as much again as A, and C as much again as B; what then must each pay?

Now suppose A to pay 107. then B

must pay 201. and C. 401. the total of which is 707. but should be 1407. Therefore, if 701. should be 1401. what should 107. be?

Answer, 201. for A's share, which doubled makes 407. for B's share, and that again doubled gives 807. for C's share, the total of which is 1407. Double position is when there can be no partition in the numbers to make a proportion. In this case, therefore, you must make a supposition twice, proceeding therein according to the tenor of the question. If neither of the supposed numbers solve the proportion, observe the errors, and whether they be greater or less than the supposition requires, and mark the errors accordingly with the sign + and -. Then multiply contrariwise the one position by the other error, and if the errors be both too great, or both too little, subtract the one product from the other, and divide the difference of the products by the difference of the errors. If the errors be unlike, as the one and the other add the products, and divide the sum thereof by the sum of the errors added together: for the proportion of the errors is the same with the proportion of the excesses or defects of the numbers supposed to be the numbers sought or, the suppositions and their errors being placed as before, work by this proportion as a general rule, viz. as the difference of the errors, if alike, or their sum, if unlike, to the difference of the suppositions, so either error fourth number, which accordingly, added to or subtracted from the supposition against it, will answer the question.

to a

POSITION, in geometry, is a term sometimes used in contradistinction to magnitude; thus a line is said to be given in position, positione data, when its situation, bearing, or direction, with regard to some other line, is given: on the contrary, a line is given in magnitude, when its length is given, but not its situation.

POSITIVE, a term of relation sometimes opposed to negative; hence a positive quantity, in algebra, is a real or affirmative quantity, or a quantity greater than nothing: thus called in opposition to a privative or negative quantity, which is less than nothing, and marked by the sign - Positive quantities are designed by the character + prefixed, or supposed to be prefixed to them.

POSITIVE, in music, denotes the little organ usually placed behind or at the feet of an organist, played with the same wind, and the same bellows, and consist

ing of the same number of pipes with the larger one, though those much smaller, and in a certain proportion: this is properly the proper choir-organ.

POSITIVE degree, in grammar, is the adjective in its simple signification, without any comparison; or it is that termination of the adjective which expresses itself simply, and absolutely, without comparing it with any other,

POSITIVE electricity. According to the Franklinian system, all bodies are supposed to contain a certain quantity of electricity: and those, that by any means are made to contain more or less than their natural quantity, are said to be positively or negatively electrified. These electricities, being first produced by the friction of glass and resin, were called by some philosophers vitreous and resinous ;. the former answering to the positive or plus electricity; the latter to the negative or minus electricity.

POSSE comitatus. The power of the county, is the attendance of all knights and others, above fifteen years of age, to assist the sheriff in quelling riots, &c.

:

POSSESSION is two-fold; actual, and in law actual possession is, when a man actually enters into lands and tenements to him descended; possession in law is, when the lands or tenements are descended to a man, and he has not as yet actually entered into them.

POSSESSIVE, in grammar, a term applied to pronouns which denote the enjoyment or possession of any thing, either in particular or in common: as meus, mine, and tuus, thine; noster, ours, and vester, yours.

POST, a word synonymous with courier, which is supposed to be originally derived from horses for the conveyance of dispatches, being positi, or placed at convenient distances, as relays or changes for those fatigued, and unable to proceed the whole journey with the desired speed. Hence it has become the practice to term horses employed for this and similar purposes, post-horses; their riders, post-boys: the houses for the reception of letters thus conveyed, postoffices; and even the drivers of chaises, postillions; and their vehicles, postchaises; it is natural, besides, to say, he who continues a journey on fresh horses, without stopping for more than necessary refreshment, rides post. The spaces between certain inns, for the reception of travellers in England, forming a post, vary from twelve to fifteen miles, beyond which it is deemed imprudent to urge a

horse, without a long interval of repose; and the charges per mile for horses furnished from those inns have occasioned continual discontent, and frequent general meetings of certain classes of the public.

Before the establishment of a system for the conveyance of important intelligence, and in the earliest state of society, it may be supposed horses were seized, or to use a modern term, put into requisition, where they were wanted; though it is still more probable, that men were tutored to run from station to station, as is now the practice in the Eastern nations, whose couriers fly their prescribed distance with astonishing velocity, and delivering their dispatches to fresh persons: they are by this means conveyed almost as rapidly as by horses. The Emperor Trajan appears to have been the first who ordained the keeping of horses for this purpose only, and the example has appeared so rational to succeeding generations, that it is highly probable posting of every description has now reached it fullest possible perfection.

It was customary, in ancient times, to convey information by boats, and in chariots, exclusive of on foot and horseback; nay, even pigeons have been taught to fly from place to place, with letters attached to them; in England, men who conveyed letters were called carriers, which was certainly, in the then state of the roads, a much more appropriate term than the present, implying, in one acceptation, exceeding swiftness. Louis XI., King of France, established the first regular conveyance of this description in the year 1464, for the more speedy and certain information he thought it necessary to possess, concerning the state of his extensive dominions; the utility of the invention was too apparent to escape the observation of the surrounding continental nations, which adopted the idea, and each suited the regulations to their own peculiar circumstances; England, alone, seems to have preferred her old and tedious system of carriers, till the twelfth year of the reign of Charles II., when Parliament passed an act, which empowered the King to establish a postoffice, and to appoint a postmaster-general. From that time to the present, numerous other acts of the legislature have been made, to improve and amend the system, which, during the time of peace, is carried on by an incredible number of clerks, and officers, and receivers, and letter-carriers, whose regularity and punctuality are not to be exceeded in any de

VOL. X.

partment of the government. In the time of Queen Anne, Sir Thomas Frankland, and John Evelyn, Esquire, held the office of postmaster-general jointly, and received a salary of 20001. per annum; about which time the following notice appeared in the London Gazette: "These are to give notice, that by the act of Parliament for establishing a general post-office, all fetters and packets, directed to and sent from places distant ten miles, or above, from the said office in London, which, before the second of this instant, June, were received and delivered by the officers of the penny-post, are now subjected to the same rates of postage as general post letters; and that for the acommodation of the inhabitants of such places, their letters will be conveyed with the same regularity and dispatch as formerly, being first taxed with the rates, and stamped with the mark of the general post-office; and that all parcels will likewise be taxed at the rate of two-shillings per ounce, as the said act directs."

Although the value of money has infinitely decreased since the above period, such has been the increase in commerce, and trade, and population, that the charges for the conveyance of letters is still comparatively moderate, as a single letter is sent one hundred and fifty miles for eight-pence. This may be attributed, in a great measure, besides, to the modern invention of mail coaches, for which the public are indebted to Mr Palmer, who has not, however, reaped that advantage from it originally intended. Those that have travelled in these vehicles need not be informed of their rapid motions, nor of the constant, uninterrupted assiduity of the coachmen, the guards, the officers of the different post-towns, and even of the hostlers, to expedite their progress; and to those who have not, and foreigners, the regulations under which they are placed must give an exalted idea of the commercial character of the British nation.

At eight o'clock in the evening of every day, the mail coaches depart from London, freighted with such letters and packets as have been conveyed during the day, either to the office in Lombardstreet, or to that place from the various receiving-offices scattered in every direction, by the letter-carriers, who walk through their districts, ringing a bell from five o'clock to six, to collect those letters which have been delayed to that late hour. The coaches, which proceed

R

to London from all parts of the kingdom, regulate their movements so as to arrive by six o'clock each morning, and from that time the sorters at Lombard-street are employed in preparing the letters for the different carriers waiting to receive them, who generally complete their delivery by twelve at noon.

Newspapers are conveyed gratis to all parts of the country, and if frivolous, vexatious, or malicious letters are sent through the medium of the post-office, upon a proper representation, the money is returned; persons are also appointed to open such letters as may be directed to individuals improperly, or who cannot be found, when they are carefully enclosed in an envelope, explaining why the seal has been violated, and returned to the writer. Letters directed to any part of England may be sent without paying; or the receiver will take the postage, and the receipt, or non-payment, is explained to the carriers by marks stamped on the letter; but all letters, sent out of England, must be paid for on putting them into the office. Other marks, pointing out the day and hour of putting the let ter into the receiver's hands, prevent the possibility of neglect without discovery; and so great is the vigilance of the officers, that though millions of money pass through the post-office, it is a very rare circumstance that dishonesty is discovered in the sorters or carriers: when an individual commits a theft of this description, he is pursued with unrelecting severity to punishment, and the office makes good the loss.

The general post-office was originally situated in Cloak-lane, near Dowgate, whence it was afterwards removed to the Black Swan, in Bishopsgate-street, and finally to the mansion of Sir Robert Vyner, in Lombard-street; and although it has been repeatedly enlarged and improved, and may answer for the purposes requir. ed, yet it must be admitted, that such an establishment requires an uniform and superb building.

The penny-post, as it was termed for more than a century, originated from the public spirit of a merchant, named Docwra, and a Mr. Murray, who, with much difficulty and great expense, in the reign of Charles H., proceeded so far as to establish it; but, strange and perverse as it may appear, every species of opposition and misrepresentation attended its progress, both from the public and the government, and, after a trial with the latter in the court of King's Bench, the

projectors had the mortification to find it adjudged to belong to the Duke of York, as a branch of the general postoffice.

In an advertisement used by them, in 1681, they say, "that undertakers have set up, and hitherto carried on the said practice with much pains and industry, and at the expense of a great sum of money, and are as desirous to continue it for the public service of their native place, as, to benefit themselves thereby; yet they have met with much opposition, and many discouragements from the self-interested, the envious, and the ignorant: from the last of which (to pass by the others at present) there are daily complaints of the delays of letters causelessly charged on the office, which hath proved very inju rious to the progress and prosperity of their honest design, and hindering the inhabitants from reaping the advantage and conveniency thereof." After some explanations how the delay complained of occurred, through the carelessness of persons not connected with the undertaking, they add, "for some remedy to prevent such unjust reflections for the time to come, and that any person may discover where the fault lies, if his letter be delayed, the undertakers have provided stamps of the like form in the margin, (similar to those still used) which shall be set on each letter every hour of the day, (at the time they are given out of their office for delivery;) and all persons are to expect their letters in an hour (little more or less) after the time stamped, according as the distance is further from, or nearer to, the office from whence they are sent; and if people will but consider, that there must be an hour's time allowed for collecting every round of letters, another for sorting and distributing, and a third for delivery, (besides an overallowance for remote parts,) they would not so often mistake in their reckonings, and expect a letter should go or come as soon as if a special messenger were immediately sent away with it, although they hope, that all ingenuous and thinking persons do find such dispatches as do answer their reasonable expectations."

An establishment of decided and obvious utility, like that of the penny-post, could not fail of succeeding in time; and accordingly we find it has flourished for more than a hundred years; but wellfounded complaints were sometimes urg ed against it during that period, which at length induced the government to take it under their immediate inspection,

at

the close of the last century, when, in order to meet the increased expenses of every portion of the undertaking, it was determined to double the charge, and from that period it received the denomination of the two-penny post. In order to facilitate the conveyance of letters and packets, boys are employed, who ride small swift horses to and from the principal office, situated in Gerard-street, Soho, where may be seen a miniature copy of the proceedings at the general post-office, already described.

lt was

POST-office, a general post-office was erected, 12 Charles II. c. 35. made perpetual, and part of the general fund, 3 George I. c. 7. The postmaster is not like a common carrier, and is not answerable for the loss of any money by post, nor can the country postmaster add any charge to the postage for carrying the letters out to the inhabitants of the town. The case has been several times tried and decided. A principal object in the erection of the post-office was, in order to have the means of inspecting letters of individuals, and discovering attempts against the Government, (see the Ordi. nance 1657); and now letters may be opened by an order from a Secretary of State. For this, and other purposes, there are several penalties levied upon persons carrying or sending letters by private conveyance. Letters coming by private ships from abroad, and even letters belonging to the owners, must also pass through the post-office.

POST, in the military art, is any place or spot of ground, fortified or not, where a body of men may make a stand and fortify themselves, or remain in a condition to fight an enemy. Hence it is said, that the post was relieved, the post was taken sword in hand, &c.

POST, advanced, is a spot of ground seized by a party to secure the army, and cover the posts that are behind.

POSTERN,in fortification is a small gate generally made in the angle of the flank of a bastion, or in that of the curtain, or near the orillon, descending into the ditch; by which the garrison may march in and out unperceived by the enemy, either to relieve the works, or to make private sallies, &c.

POSTIL, a name anciently given to a note in the margin of the bible, and afterwards to one in any other book posterior to the text.

POSTING, among merchants, the putting an account forward from one book to

another, particularly from the journal or waste-book to the ledger.

POSTULATE, in mathematics, &c. is described to be such an easy and self-evident supposition, as needs no explication or illustration to render it intelligible; as, that a right line may be drawn from one point to another; that a circle may be described on any centre given, of any magnitude, &c.; however, authors are not well agreed as to the signification of the term postulatum; some make the difference between axioms and postulata to be the same as that between theorems and problems; axioms, according to those authors, being truths that require no demonstration. But others will have it, that axioms are primitive and common to all things, partaking of the nature of quantity, and which therefore may become the objects of mathematical science; such as number, time, extension, weight, motion, &c. and that postulata relate particularly, to magnitude, strictly so called, as to things having local extension, such as lines, surfaces, and solids; so that in this sense of the word postulatum, Euclid, besides axioms, or those principles which are common to all kinds of quantities, has assumed certain postulata to be granted him peculiar to extensive magnitude. Hence several of the principles assumed in his elements, and ranked among the axioms by the moderns, are by Proclus ranked among the postulata, which has induced Dr. Wallis to judge, that the last of the two senses given to the term postulatum is most agreeable to the meaning of the ancient geometers.

POSTURE, in painting and sculpture, the situation of a figure with regard to the eye, and of the several principal members thereof with regard to one another, whereby its action is expressed. A considerable part of the art of a painter consists in adjusting the postures, in giving the most agreeable postures to his figures, in accommodating them to the characters of the respective figures, and the part each has in the action, and in conducting and pursuing them throughout.

POTAMOGETON, in botany, pond. weed, a genus of the Tetrandria Tetragynia class and order. Natural order of Inundatæ. Naiades, Jussieu. Essential character calyx none; petals four; style none; seeds four. There are fourteen species: these are perennial, herbaceous plants, inhabitants of the wa

ter.

POTASH, in chemistry, a substance