to two pieces of thin brass; and these pieces of brass are fixed at the other ends by two screws d,e, to a stronger piece of brass bf, which goes close to the ruler A B, and has a joint at X turning upon a screw; below this joint is a piece of round brass about six inches long, which goes into a hole made in the top of the staff, and may be raised higher or lower, by means of a screw S: CDE represents part of this staff, the whole length of which is about three feet, and at the bottom is a rank screw made of iron and fixed to the staff. HI is a wire twenty-two inches long, with a screw at h to go into the hole b; the piece of brass wire bent into the form ik is fixed to the wire HI by the screw k; and the part i goes into the hole f in the brass piece bf. The small wire K L is about twelve inches long, and flatted at K, at which place is a little hole above one-eighth of an inch in diameter; this wire KL is fitted to the holes l, m, n, o, which are made in the larger wire H I, and it may be placed higher or lower by means of a small screw. This instrument is used in the following manner: fix a paper upon a drawing board, as in fig. 4, and divide the paper lengthways into nineteen equal parts, and perpendicularly into fourteen equal parts; making these divisions greater or smaller according to your design. Then take the staff, and fix it strongly in the ground by means of a screw at bottom, and at a convenient distance from the prospect which you intend to take. Now put the instrument together as in fig. 5, and fix the ruler A B exactly horizontal by means of the plummet on the perpendicular ruler and Lat. perspicar. Quicksighted; PERSPICA'CIOUS, adj. PERSPICACITY, N. s. sharp of sight: quickness of sight. He that laid the foundations of the earth cannot be excluded the secrecy of the mountains; nor can there any thing escape the perspicacity of those eyes which were before light, and in whose optics there is no opacity. Browne. It is as nice and tender in feeling as it can be perspicacious and quick in seeing. South. PERSPICIL, n. s. Lat. perspicillum. A glass through which things are viewed; an optic glass. Not used. Let truth be Ne'er so far distant, yet chronology, As when the rosy morn buds into day. Crashaw. The perspicil, as well as the needle, hath enlarged the habitable world. Glanville's Scepsis. PERSPICUOUS, adj. Fr. perspecuité; PERSPICUOUSLY, adv. Lat. perspicuus. PERSPICUOUSNESS, n. s. (Clear; translucent; PERSPICU'ITY. transparent; such as may be seen through; the adverb and noun substantive corresponding: perspicuity is more commonly used for clearness to the mind; and hence for precision of expression or language. the brass joint X; then fix the wire K L, so as to have the eye-hole exactly level with the horizon or equal to the height of the eye, and take care to have the greatest distance of the eye-hole from the ruler equal to the whole length of the longest ruler A B, and never less than the distance hl. Having thus fixed the instrument, proceed to make the drawing; look through the eye-hole, and then move the perpendicular ruler in the groove, till you get one edge exactly against some principal object; then will the parts upon the ruler show how high the object is from the bottom of the ruler, i. e. from the bottom of the picture, and you will also know its apparent height; therefore transfer this to the paper m those squares which correspond with the divi sions upon the rulers. For the breadth of objects, move the perpendicular ruler so as to be even with the sides of an object, and the divisions upon the lower ruler will show their apparent breadths. After the same manner, get the places and apparent sizes of as many principal objects as are necessary for assisting you, in completing the whole drawing, which may be done by this method with great exactness. When the drawing is finished, the instrument may be taken to pieces and put into a box, which may serve as a drawing board; the top M may be screwed into the staff, which will serve as a walking-stick, and the stool to sit on may be made very portable; so that every part of this apparatus may be carried by one person without any inconvenience. Kirby, b. ii. p. 65, &c. This last instrument has been found particularly convenient in taking views of extensive landscapes, or buildings. PERSPIRATION, in medicine, is the evacuation of the juices of the body through the pores of the skin. Perspiration is distinguished into sensible and insensible; and here sensible perspiration is the same with sweating, and insensible perspiration that which escapes the notice of the senses. This last is the idea affixed to the word perspiration when used alone. The secretory organ is composed of the extremities of the cutaneous arteries. The smell of the perspirable fluid, in a healthy man, is fatuous and animal; its taste manifestly salt and ammoniacal. In consistence it is vaporous or aqueous; and its specific gravity in the latter state is greater than that of water. For the most part it is yellowish, from the passage of the subcutaneous oil, and sebaceous matter of the subcutaneous glands. Whatever form it takes, the liquid that escapes from the skin is composed, according to Thenard, of a great deal of water, a small quantity of acetic acid, of muriate of soda and potassa, a small quantity of earthy phosphate, an atom of oxide of iron, and a trace of animal matter. Berzelius considers the acid of sweat not the same as acetic acid, but like the lactic acid of Scheel. The skin exhales besides an oily matter, and some carbonic acid. Experiments have been made to determine the quantity of transpiration which is formed in a given time, and the variations that this quantity undergoes according to circumstances. The first were those of Sanctorius, who, during thirty years, weighed every day, with extreme care, and an indefatigable patience, his food and his drink, his solid and liquid excretions, and even himself. Sanctorius arrived at no exact results. Since his time several philosophers and physicians have been employed on the same subject with more success; but the most remarkable labor in this way is that of Lavoisier and Seguin. These philosophers were the first who distinguished the loss that takes place by pulmonary transpiration from that of the skin. Seguin shut himself up in a bag of gummed silk, tied above his head, and presenting an opening, the edges of which were fixed round his mouth by a mixture of turpentine and pitch. In this manner only the humor of the pulmonary transpiration passed into the air. In order to know the quantity, it was sufficient to weigh himself, with the bag, at the beginning and end of the experiment, in a very fine balance. By repeating the experiment out of the bag, he determined the whole quantity of humor transpired; so that, by deducting from this the quantity that he knew had passed out from the lungs, he had the quantity of humor exhaled by the skin. Besides, he took into account the food that he had used, his excretions solid and liquid, and generally all the causes that could have any influence upon the of Lavoisier and Seguin are these:-1. The transpiration. By following this plan, the results greatest quantity of insensible transpiration (the pulmonary included) is 25-6 grs. troy per minute; consequently 3 ozs. 1 drm. 36 grs. per hour; and 6 lbs. 4 ozs. 6 drms. 24 grs. in twentyfour hours. 2. The least considerable loss is 8.8 grs. per minute; consequently 2 lbs. 2 ozs. 3 drms. in twenty-four hours. 3. It is during the digestion that the loss of weight occasioned by insensible transpiration is at its minimum. 4. The transpiration is at its maximum immediately after dinner. 5. The mean of the insensible transpiration is 14.4 grs. per minute; in the mean 14.4 grs. 8-8 depend on cutaneous transpiration, and 5-6 upon the pulmonary. 6. The cutaneous transpiration alone varies during and after repasts. 7. Whatever quantity of food is taken, or whatever are the variations of the atmosphere, the same individual, after having augmented in weight by all the food that he has taken, returns, in twenty-four hours, to the same weight nearly that he was the day before, provided he is not growing, or has not eaten to excess. The cutaneous transpiration has various uses. It keeps up the suppleness of the epidermis, and thus favors the exercise of the tact and the touch. It is by evaporation along with that of the lungs, the principal means of cooling, by which the body maintains itself within certain limits of temperature; also its expulsion from the economy appears very important, for every time that it is diminished or suspended, derangements of more or less consequence follow, and many diseases are not arrested until a considerable quantity of sweat is expelled. It cannot be doubted that carbon is emitted from the skin; but in what state, the experiments hitherto made do not enable us to decide. Cruickshanks found that the air of the glass vessel in which his hand and foot had been confined for an hour, contained carbonic acid gas; for a candle burned dimly in it, and it rendered lime-water turbid. And Jurine, that air which had remained for some time in contact with the skin consisted almost entirely of carbonic acid gas. The same conclusion may be drawn from the experiments of Ingenhousz and Milly. Trousset has lately observed that air was separated copiously from a patient of his, while bathing. The skin emits also a particular odorous substance. That every animal has a peculiar smell is well known: the dog can discover his master, and even trace him to a distance by the scent. Cruickshanks has made it probable that this matter is an oily substance, or at least that there is an oily substance emitted by the skin. He wore repeatedly, night and day, for a month, the same under waistcoat of fleecy hosiery, during the hottest part of the summer. At the end of this time he always found an oily substance accumulated in considerable masses on the nap of the inner surface of the waistcoat, in the form of black tears. When rubbed on paper, it rendered it transparent, and hardened on it like grease. It burned with a white flame, and left behind it a charry residuum. Berthollet has concluded that the acid which is present is the phosphoric; but this has not been proved. Fourcroy and Vauquelin have ascertained that the scurf which collects upon the skins of horses consists chiefly of phosphate of 'ime, and urea is even sometimes mixed with it. According to Thenard, however, the acid contained in sweat is the acetous; which, he likewise observes, is the only free acid contained in urine and in milk, this acid existing in both of them when quite fresh. His account of his examination of it is as follows:-The sweat is more or less copious in different individuals; and its quantity is perceptibly in the inverse ratio of that of the urine. All other circumstances being similar, much more is produced during digestion than during repose. The maximum of its production appears to be twenty-six grains and two-thirds in a minute; the minimum nine grains, troy weight. It is much inferior, however, to the pulmonary transpiration; and there is likewise a great difference between their nature and manner of formation. The one is a product of a particular secretion, similar in some sort to that of the urine; the other, composed of a great deal of water and carbonic acid, is the product of a combustion gradually effected by the atmospheric air. The sweat, in a healthy state, very sensibly reddens litmus paper or infusion. In certain diseases, and particularly in putrid fevers, it is alkaline; yet its taste is always rather saline, and more similar to that of salt than acid. Though colorless, it stains linen. Its smell is peculiar, and insupportable when it is concentrated, which is the case in particular during distillation. But before he speaks of the trials to which he subjected it, and of which he had occasion for a great quantity, he describes the method he adopted for procuring it, which was similar to that of Cruickshanks. Human sweat, according to Thenard, is formed of a great deal of water, free acetous acid, muriate of soda, an atom of phosphate of lime and oxide of iron, and an inappreciable quantity of animal matter, which approaches much nearer to gelatin than to any other substance. Perspiration varies in respect to, 1. The temperature of the atmosphere. Thus men have a more copious, viscid, and higher-colored sweat in summer than in winter, and in warm countries, than in colder regions. 2. Sex.-The sweat of a man is said to smell more acrid than that of a woman. 3. Age. The young are more subject to sweat than the aged, who, during the excessive heat of the summer, scarcely sweat at all. 4. Ingesta. An alliacious sweat is perceived from eating garlick; a leguminous from peas; an acid from acids; a fetid from animal food only; and a rancid sweat from fat foods, as is observed in Greenland. A long abstinence from drink causes a more acrid and colored sweat; and the drinking a great quantity of cold water in summer a limpid and thin sweat. 5. Medicines.-The sweat of those who have taken musk, even moderately, and assafœtida, or sulphur, smells of their respective natures. 6. Region of the body.-The sweat of the head is greasy; on the forehead it is more aqueous; under the axillæ very unguinous; and in the interstices of the toes it is very fetid, forming in the most healthy man blackish sordes. 7. Diseases. In this respect it varies very much in regard to quantity, smell, and color; for the sweat of gouty persons is said to turn blue vegetable juices to a red color. Some men also have a lucid sweat, others a sweat tinging their linen of a cerulean color. PERSUADE', v. a. Fr. persuader; Span. and Port. persuadir; Ital. and Lat. persuadere, per- 1 suadeo. To induce; bring to an opinion; influence by expos tulation or argu 6 argument. Dr. Johnson says, persuasion seems ment; inculcate by rather applicable to the passions, and argument to the reason;' but this is not always observed: in an obsolete sense, to treat by persuasion: a persuader is one who thus treats or influences another; an officious adviser or importuner : persuasible is to be persuaded; the noun substantive that follows corresponding: persuasion is the act of persuading; state of being persuaded, or opinion to which one is persuaded: persuasive and persuasory, having the power to persuade or influence by argument; the adverb and noun substantive corresponding. Let every man be fully persuaded in his own mind. Romans. We are persuaded better things of you, and things that salvation. accompany Hebrews vi. 9. Joy over them that are persuaded to salvation. Esdras vii. An opinion of the successfulness of the work being as necessary to found a purpose of undertaking it, as either the authority of commands, or the persuasiveness of promises, or pungency of menaces can be. Hammond's Fundamentals. To children, afraid of vain images, we persuade confidence by making them handle and look nearer such things. Taylor. How incongruous would it be for a mathematician to persuade with eloquence, to use all imaginable insinuations and intreaties, that he might prevail with his hearers to believe that three and three make six! Wilkins. The obedient and the men of practice shall ride upon those clouds, and triumph over their present imperfections; till persuasion pass into knowledge, and knowledge advance into assurance, and all come at length to be completed in the beatific vision. · South. Notwithstanding the weight and fitness of the arguments to persuade, and the light of man's intellect to meet this persuasive evidence with a suitable assent, no assent followed, nor were men thereby actually persuaded. Id. It makes us apprehend our own interest in that obedience, makes us tractable and persuasible, contrary to that brutish stubbornness of the horse and mule, which the Psalmist reproaches. Government of the Tongue. When we have no other certainty of being in the right, but our own persuasions that we are so; this may often be but making one error the gage for an other. Id. Spectator. A lady bids me in a very pert manner mind my own affairs, and not pretend to meddle with their linen. Addison. All servants might challenge the same liberty, and grow pert upon their masters; and, when this sauciness became universal, what less mischief could be expected than an old Scythian rebellion? Collier on Pride. I find no other difference betwixt the common town-wits and the downright country fools, than that the first are pertly in the wrong, with a little more gaiety and the last neither in the right nor the wrong. Pope. : Dulness delighted eyed the lively dunce, Remembering she herself was pertness once. Vanesso Scarce listened to their idle chat, When you pertly raise your snout, Id. Swift Id. For sheer wit and humour passes. There is in Shaftesbury's works a lively pertness and a parade of literature; but it is hard that we should be bound to admire the reveries. Watts. PERTAIN, v. n. Lat. pertinco. To belong; to relate; appertain. As men hate those that effect that honour by ambition, which pertaineth not to them; so are they more odious, who through fear betray the glory which they have, Hayward. A cheveron or rafter of an house, a very honourable bearing, is never seen in the coat of a king, because it pertaineth to a mechanical profession. Peacham. PERTH, an ancient and celebrated city of of the whole kingdom, is situated in a fine but Scotland, the capital of Perthshire, and formerly low plain on the west bank of the Tay, which takes a bend to the east about a mile below the city. The waters of the Almond are also brought to the town by a canal. Portions of the plain north and south are called the North and South Inches, each of which is about a mile and a half in circumference, and is used both for the profit and pleasure of the inhabitants. On the north Inch is a good race ground. The old part of the town is uniform in its plan, consisting of four streets from east to west, crossed by others at right angles. At the east end of High Street stood the old town house, county hall and prison, now rebuilding after a design by Smirke, on the site of the former palace of the Gowrie family. In the High Street is the guildhall, a plain building, and at the west end of it a modern church, with a steeple 140 feet high. In George Street is the public coffee room, also a handsome modern building. There are several other good halls in the city, particularly that of the royal arch mason lodge, on the site of the ancient parliament house of Scotland. A little to the south and west of the new church is an old hospital, founded by James VI., now used as warehouses. Between the High Street and the South Street stands the church of St. John the Baptist, a building of very great antiquity, with a high spire, and is fitted up for three places of worship called the East, Middle, and West kirks. Chapels for the dissenters are also numerous. The episcopal chapel in Prince's Street is a very elegant building. The whole of the Blackfriars ground on the north, and a considerable space of ground on the south side of the town, have within these twenty years been laid out for buildings, and a New Town may be then said to have arisen, containing a considerable number of streets, with many noble houses. Adjoining the North Inch is a crescent, place, and terrace, the latter a row of very fine buildings, in the centre of which is the Seminaries, a handsome fabric, where the various branches of education are taught. An elegant new theatre forms the western termination of the crescent, and a fine barrack terminates Athol Street in the same direction. At the extremity of South Inch stands a depot, built by government for the reception of prisoners of war, now used for military stores. It is considered one of the most complete and well arranged establishments of this kind in Great Britain. Two banking companies belong to the town, and there is also a branch of the bank of Scotland, and another of the British Linen Company, established here. The grammarschool of Perth has long been accounted one of the best in Scotland, and has produced many eminent statesmen and scholars. A literary and antiquarian society has also been established. Perth was only provided formerly with a wooden bridge over the Tay. This gave place in 1772 to a new one of stone, designed by Mr. Smeaton, and begun in 1766. It consists of ten arches, is 906 feet in length, and twentytwo in breadth, and was built at an expense of about £30,000. At the east end of the bridge is the bridge end or burgh of Kinnoul. The salmon fishery on the Tay is very extensive, and the annual rent may be estimated at about £7000, of which Perth shares about £1000. The salmon are sent to London, packed in ice or pickled; a smack sailing every third or fourth day during the season. The staple manufacture of Perth is linen; but of late the cotton manufacture has greatly rivalled it. There are upwards of 2500 looms employed in the town, which manufacture linen and cotton goods, besides extensive manufactures of leather articles of all kinds. In the neighbourhood are various manufacturing villages, of which Tulloch, Craigee-mill, and Muirtoun of Dalhousie, are in the parish of Perth. Perth is a royal borough, and joins with Dundee, Forfar, Cupar of Fife, and St. Andrews, in electing a representative in the British imperial parliament. It had a royal charter from king David I., who died in 1153, and which was renewed and confirmed by another from king William I. in 1210, which is still extant. It is governed by a provost, four bailies (v three merchants and one tradesman), a dean of guild, treasurer, and nineteen counsellors. E gave formerly the title of earl to the Drummond family, and the fourth earl was created duke of Perth by James II.: but all the titles of the family became forfeited by its attachment to the Stuarts. Various accounts are given of the origin and ancient history of this place: some writers a cribing its first foundation to the Roman general Agricola; who is said to have fixed his camp here about A. D. 70, from the resemblance the scenery to that of Rome. The soldiers, when they first saw the river Tay, and the adjacent plain, are recorded to have exclaimed, Ecce Tiber! Ecce Campus Martius! Behold the Tiber! Behold the field of Mars! Hence the Tay, we are told, was called New Tiber, by the Italians; and Fordun, a Scottish historian, gives the name of Tyber-Mere, to an extensive moor west of the town. An aqueduct, said to have been constructed here by Agricola, is still in existence. When the town was fortified it supplied the ditches. Necham, an English writer, who gave lectures on history at Paris in 1180, describes Perth as a place of opulence; and, in 1210, according to the Scottish historians, it was strongly fortified by king William, who renewed its charter, and granted many additional privileges to the city. At this time, and indeed until the reign of the Stuart family, Perth was reckoned the capital city of Scotland, when kings were crowned at Scone. Between the years 1201 and 1459 no fewer than fourteen parliaments were held here. It was then likewise, as it is still, an extensive commercial town. Fordun says that the mer chants of Perth visited, in their own ships, the Hanse Towns. The Flemings of this and the following cen tury also frequented the port of Perth, and individuals of that nation connected with the linen and woollen manufactures appear to have fixed their abode in the town. King William, however, put the foreign merchants of Perth under restrictions; and, to prevent the settlement of foreign manufacturers there, granted in his charter that the burgesses might have a merchant guild of their own, fullers and weavers excepted.' Edward I. of England made it the residence of his deputies: Robert Bruce attacked this town in 1306 and 1311, but was repulsed on the former occasion by the earl of Pembroke; on the latter, after an obstinate siege of six weeks, he succeeded in storming the fortifications, which he levelled with the ground. After the battle of Duplin these were rebuilt by Edward Baliol. In 1335 our Edward III. took possession of Perth, and resided in it. John, earl of Cornwall, brother to that monarch, is said to have died here in October 1336; receiving, according to Fordun, his mortal wound from the king's own dagger. In 1339 Perth endured a long siege by the regent Robert, and was only taken by draining the ditch. In 1437 James I. of Scotland was murdered at the Black Friars' monastery by Robert Graham, who wounded him |