Powder of the first strength.] Take leaves of juniper, juniper-berries pounded, ears of wheat, guaiacum wood pounded, of each six pounds; common saltpetre pounded, eight pounds; sulphur pounded, six pounds; Smyrna tar, or myrrh, two pounds: mix all the above ingredients together, which will produce a pood of the powder of fumigation of the first strength. [N. B. A pood is 40 pounds Russian, which are equal to 35 pounds and a half or 36 pounds English avoirdupoise.]

Powder of the second strength.] Take southernwood cut into small pieces, four pounds; juniper-berries pounded, three pounds; common saltpetre pounded, four pounds; sulphur pounded, two pounds and a half; Smyrna tar, or myrrh, one pound and a half: mix the above together which will produce half a pood of the powder of fumigation of the second strength.

Odoriferous powder.] Take the root called kalmus cut into small pieces, three pounds; leaves of juniper cut into small pieces, four pounds; frankincense pounded grossly, one pound; storax pounded, and rose flowers, half a pound; yellow amber pounded, one pound; common saltpetre pounded, one pound and a half; sulphur, a quarter of a pound: mix all the above together, which will produce nine pounds and three quarters of the odoriferous powder.

Remark on the powder of fumigation.] If guaiacum cannot be had, the cones of pines or firs may be used in its stead; likewise common tar of pines and firs may be used instead of the Smyrna tar, or myrrh, and mugwort may supply the place of southernwood.

Thucydides, who was himself infected, lib. ii. gives us an account of a dreadful plague which happened at Athens, about the year before Christ 430, while the Peleponnesians under the command of Archidamus wasted all their territory abroad; but of these two enemies the plague was by far the most dreadful and

severe.

The most dreadful plague that ever raged at Rome was in the reign of Titus, A. D. 80. The emperor left no remedy unattempted to abate the malignity of the distemper, acting during its continuance like a father to his people. The same fatal disease raged in all the provinces of the Roman empire in the reign of M. Aurelius, A. D. 167, and was followed by a dreadful famine, by earthquakes, inundations, and other calamities. The Romans believed that Esculapius sometimes entered into a serpent, and cured the plague.

About the year 430 the plague visited Britain, just after the Picts and Scots had made a formidable invasion of the southern part of the island. The plague raged with uncommon fury, and swept away most of those whom the sword and famine had spared, so that the living were scarcely sufficient to bury the dead.

About the year 1348 the plague became almost ge

In the year 1656 the plague was brought from Sardinia to Naples, being introduced into the city by a transport with soldiers on board. It raged with excessive violence, carrying off in less than six months 400,000 of the inhabitants. The distemper was at first called by the physicians a malignant fever; but one of them affirming it to be pestilential, the viceroy, who was apprehensive lest such a report would occasion all communication with Naples to be broke off, was offended with this declaration, and ordered him to be imprisoned. As a favour, however, he allowed him to return and die in his own house. By this proceeding of the viceroy, the distemper being neglected, made a most rapid and furious progress, and filled the whole city with consternation. The streets were crowded with confused processions, which served to spread the infection through all the quarters. The terror of the people increased their superstition; and it being reported that a certain nun had prophesied that the pestilence would cease upon building a hermitage for her sister nuns upon the hill of St Martin's, the edifice was immediately begun with the most ardent zeal. Persons of the highest quality strove who should perform the meanest offices; some loading themselves with beams, and others carrying baskets full of lime and nails, while persons of all ranks stripped themselves of their most valuable effects, which they threw into empty hogsheads placed in the streets to receive the charitable contributions. Their violent agitation, however, and the increasing heats, diffused the malady through the whole city, and the streets and the stairs of the churches were filled with the dead; the number of whom, for some time of the month of July, amounted daily to 15,000.

The viceroy now used all possible precautions to abate the fury of the distemper, and to prevent its spreading to the provinces. The infection, however, desolated the whole kingdom, excepting the provinces of Otranto and the Farther Calabria, and the cities of Gaeta, Sorrento, Paolo, and Belvidere. The general calamity was increased in Naples by malecontents, who insinuated that the distemper had been designedly introduced by the Spaniards, and that there were people in disguise who went through the city sowing poisoned dust. This idle rumour enraged the populace, who began to insult the Spanish soldiers, and threaten a sedition; so that the viceroy, to pacify the mob, caused a criminal to be broke upon the wheel, under pretence that he was a disperser of the dust. A violent and plentiful rain falling about the middle of August, the distemper be gan to abate; and on the eighth of December the physicians made a solemn declaration that the city was entirely free from infection.

Of the dreadful plague which raged at London in 4 F 2

the

Plugue symptoms; but whether from that or any other cause, does not appear certain."

Plan.

Oil rubbed into the skin acts as a preventive, as well as a cure of the plague. When the operation is performed to prevent infection, it is successfully performed with that view at Smyrna, as often as the plague make its appearance in the city. As it is not done for the purpose of promoting perspiration, it is not requisite that it should be performed with the same speed as when for curing the disorder; nor is it necessary to abstain from flesh, and to use soups; but it will be proper to use only fowls or veal for some days, without any seasoning. It will in fine be necessary to guard against indigestible food, and such liquors as might put in motion or inflame the mass of the blood.

This interesting discovery merits the attention of all medical men; for if olive oil has been found efficacious in curing or preserving against one species of infection, it is not absurd to suppose that the same or other kinds of oil might be productive of much benefit in other malignant infectious diseases. We hope soon to hear of some trial being made with it in this country. Would it be of any service in the yellow fever, so prevalent in the western world?

PLAIN, or PLANE, in general, an appellation given to whatever is smooth and even, or simple, obvious, and easy to be understood; and, consequently, stands opposed to rough, enriched, or laboured.

A plain figure, in geometry, is an uniform surface; from every point of whose perimeter right lines may be drawn to every other point in the same.

A plain angle is one contained under two lines, or surfaces, in contradistinction to a solid angle. See ANGLE under GEOMETRY.

The doctrine of plain triangles, as those included under three right lines, is termed plain trigonometry. See the article TRIGONOMETRY.

nectes.

PLAIN-Chart. See the article CHART. PLAIN-Sailing. See NAVIGATION. PLAISE, the English name of a species of pleuroSee PLEURONECTES, ICHTHYOLOGY Index. PLAN, in general, denotes the representation of something drawn on a plane; such are maps, charts, ichnographies, &c. See MAP, CHART, &c.

The term plan, however, is particularly used for a draught of a building, such as it appears, or is intended to appear, on the ground, showing the extent, division, and distribution of its area or ground-plot into apartments, rooms, passages, &c.

A geometrical plan is that wherein the solid and vacant parts are represented in their natural proportions.

The raised plan of a building is the same with what is otherwise called an elevation or orthography. See ORTHOGRAPHY.

A perspective plan is that exhibited by degradations or diminutions, according to the rules of perspective. See PERSPECTIVE.

To render plans intelligible, it is usual to distinguish the massives with a black wash; the projectures of the ground are drawn in full lines, and those supposed over them in dotted lines. The augmentations or alterations to be made are distinguished by a colour different from what is already built; and the tints of each plan made lighter as the stories are raised.

In large buildings it is usual to have three several Plan plans for the three first stories.

PLANCUS, FRANCIS, doctor of physic, was born at Amiens in 1696, and died on the 19th of September 1765, aged 69 years. He is the author of some works which have had considerable reputation. 1. A complete System of Surgery, in 2 vols in 12mo; a treatise much recommended by surgeons to their pupils. 2. A choice Library of Medicine, taken from periodical publications, both French and others: this curious collection, continued and completed by M. Goulin, makes 9 vols in 4to, or 18 vols in 12mo. 3. A Translation of Vander Wiel's Observations on Medicine and Surgery, 1758, 2 vols in 12mo. Plancus was also the editor of various editions of works on medicine and surgery, which he enriched with notes.

PLANE, in Geometry, denotes a plain surface, or one that lies evenly between its bounding lines: and as a right line is the shortest extension from one point to another, so a plane surface is the shortest extension from one line to another.

In astronomy, conics, &c. the term plane is frequently used for an imaginary surface, supposed to cut and pass through solid bodies; and on this foundation is the whole doctrine of conic sections built. See ASTRONOMY, CONIC Sections, &c.

In mechanics, planes are either horizontal, that is, parallel to the horizon, or inclined thereto. See ME

CHANICS.

The determining how far any given plane deviates from an horizontal line, makes the whole business of levelling. See the article LEVElling.

In optics, the planes of reflection and refraction are those drawn through the incident and reflected or refracted rays. See OPTICS.

In perspective we meet with the perspective plane, which is supposed to be pellucid, and perpendicular to the horizon; the horizontal plane, supposed to pass through the spectator's eye, parallel to the horizon; the geometrical plane, likewise parallel to the horizon, wherein the object to be represented is supposed to be placed, &c. See PERSPECTIVE.

The plane of projection in the stereographic projection of the sphere, is that on which the projection is made, corresponding to the perspective plane. See PROJECTION.

PLANE, in joinery, an edged tool or instrument for paring and shaving of wood smooth. It consists of a piece of wood very smooth at bottom, as a stock or shaft; in the midst of which is an aperture, through which a steel edge, or chissel, placed obliquely, passes; which, being very sharp, takes off the inequalities of the wood along which it slides..

PLANE-Tree, in Botany. See PLATANUS.

PLANET, a celestial body, revolving round the sun as a centre, and continually changing its position with respect to the fixed stars; whence the name planet, which is a Greek word, signifying "wanderer."

The planets are usually distinguished into primary and secondary. The primary ones, called by way of eminence planets, are those which revolve round the sun as a centre; and the secondary planets, more usually called satellites or moons, are those which revolve round a primary planet as a centre, and constantly attend it. in its revolution round the,sun. The

Planet.

That the planets are opaque bodies, like our earth, is thought probable for the following reasons. I. Since in Venus, Mercury, and Mars, only that part of the disk illuminated by the sun is found to shine; and again, Venus and Mercury, when between the earth and the sun, appear like dark spots or macula on the sun's disk; it is evident, that Mars, Venus, and Mercury, are opaque bodies, illuminated with the borrowed light of the sun. And the same appears of Jupiter, from its being void of light in that part to which the shadow of the satellites reaches, as well as in that part turned from the sun; and that his satellites are opaque, and reflect the sun's light, is abundantly shown. Again, since Saturn, with his ring and satellites, only yield a faint light, fainter considerably than that of the fixed stars, though these be vastly more remote, and than that of the rest of the planets; it is past doubt that he too with his attendants are opaque bodies. 2. Since the sun's light is not transmitted through Mercury and Venus, when placed against him, it is plain they are dense opaque bodies; which is likewise evident of Jupiter, from his hiding the satellites in his shadow; and therefore, by analogy, the same may be concluded of Saturu. 3. From the variable spots of Venus, Mars, and Jupiter, it is evident these planets have a changeable atmosphere; which changeable atmosphere may, by a like argument, be inferred of the satellites of Jupiter; and therefore, by similitude, the same may be concluded of the other planets. 4. In like manner, from the mountains observed in Venus, the same may be supposed in the other planets. 5. Since, then, Saturn, Jupiter, and the satellites of both, Mars, Venus, and Mercury, are opaque bodies shining with the sun's borrowed light, are furnished with mountains, and encompassed with a changeable atmosphere; they have, it is concluded, waters, seas, &c. as well as dry land, and are bodies like the moon, and therefore like the earth. And hence it seems also highly probable, that the other planets have their animal inhabitants as well as our earth.

PLANETARIUM, an astronomical machine, so called from its representing the motions, orbits, &c. of the planets, agreeable to the Copernican system. See ASTRONOMY.

PLANETARY, something that relates to the planets. Hence we say, planetary worlds, planetary inhabitants, &c. See PLANET.

PLANETARY System, is the system or assemblage of the planets, primary and secondary, moving in their respective orbits, round their common centre the sun. See ASTRONOMY.

PLANETARY Days.-Among the ancients, the week was shared among the seven planets, each planet having its day. This we learn from Dion Cassius and Plutarch, Sympos. 1. 4. q. 7. Herodotus adds, that it was the Egyptians who first discovered what god, that is, what planet, presides over each day; for that among this people the planets were directors. And hence it is, that in

most European languages the days of the week are still Planetary denominated from the planets; Sunday, Monday, &c. See WEEK.

The

PLANETARY Years, the periods of time in which the several planets make their revolutions round the sun or earth. As from the proper revolution of the sun, the solar year takes its original; so from the proper revolutions of the rest of the planets about the earth, so many sorts of years do arise, viz. the Saturnian year, which is defined by 29 Egyptian years, 174 hours, 58 minutes, equivalent in a round number to 30 solar years. Jovial year, containing 317 days, 14 hours, 59 minutes. -The Martial year, containing 321 days, 23 hours, 31 minutes. For Venus and Mercury, as their years, when judged of with regard to the earth, are almost equal to the solar year; they are more usually estimated from the sun, the true centre of their motions: in which case, the former is equal to 224 days, 16 hours, 40 minutes; the latter to 87 days, 23 hours, 14 minutes.

PLANIMETRY, that part of geometry which considers lines and plain figures, without considering their height or depth. See GEOMETRY.

PLANISPHERE, signifies a projection of the sphere, and its various circles, on a plane; in which sense, maps, whereon are exhibited the meridians and other circles of the sphere, are planispheres. See MAP.

PLANT is defined to be an organical body, destitute of sense and spontaneous motion, adhering to an other body in such a manner as to draw from it its nourishment, and having a power of propagating itself by seeds.

The vegetation and economy of plants is one of those subjects in which our knowledge is extremely circumscribed. A total inattention to the structure and economy of plants is the chief reason of the small progress that has been made in the principles of vegetation, and of the instability and fluctuation of our theories concerning it; for which reason we shall give a short description of the structure of plants, beginning with the seed, and tracing its progress and evolution to a state of maturity.

1. Of Seeds.] The seeds of plants are of various figures and sizes. Most of them are divided into two lobes; though some, as those of the cress-kind, have six; and others, as the grains of corn, are not divided, but entire.

But as the essential properties of all seeds are the same, when considered with regard to the principles of vegetation, our particular descriptions shall be limited to one seed, viz. the great garden-bean. Neither is the choice of this seed altogether arbitrary; for, after it begins to vegetate, its parts are more conspicuous than many others, and consequently better calculated for investigation.

Plant.

This seed is covered with two coats or membranes. The outer coat is extremely thin, and full of pores; but may be easily separated from the inner one (which is much thicker), after the bean has been boiled, or lain a few days in the soil. At the thick end of the bean there is a small hole visible to the naked eye, immediately over the radicle or future root, that it may have a free passage into the soil (fig. 1. A). When these coats are Plate taken off, the body of the seed appears, which is divid- COU

ed into two smooth portions or lobes. The smoothness of the lobes is owing to a thin film or cuticle with which they are covered.

At the basis of the bean is placed the radicle or future root (fig. 3. A). The trunk of the radicle, just as it enters into the body of the seed, divides into two capital branches, one of which is inserted into each lobe, and sends off smaller ones in all directions through the whole substance of the lobes (fig. 4. AA). These ramifications become so extremely minute towards the edges of the lobes, that they require the finest glasses to render them visible. To these ramifications Grew and Malpighi have given the name of seminal root; because, by means of it, the radicle and plume, before they are expanded, derive their principal nourishment.

The plume, bud, or germ (fig. 3.), is inclosed in two small corresponding cavities in each lobe. Its colour and consistence is much the same with those of the radicle, of which it is only a continuation, but having a quite contrary direction; for the radicle descends into the earth, and divides into a great number of smaller branches or filaments; but the plume ascends into the open air, and unfolds itself into all the beautiful variety of stem, branches, leaves, flower, fruit, &c. The plume in corn shoots from the smaller end of the grain, and amongst maltsters goes by the name of acrospire.

The next thing to be taken notice of is the substance or parenchymatous part of the lobes. This is not a mere concreted juice, but is curiously organized, and consists of a vast number of small bladders resembling those in the pith of trees (fig. 5.)

Besides the coats, cuticle, and parenchymatous parts, there is a substance perfectly distinct from these, distributed in different proportions through the radicle, plume, and lobes. This inner substance appears very plainly in a transverse section of the radicle or plume. Towards the extremity of the radicle it is one entire trunk; but higher up it divides into three branches; the middle one runs directly up to the plume, and the other two pass into the lobes on each side, and spread out into a great variety of small branches through the whole body of the lobes (fig. 4.). This substance is very properly termed the seminal root: for when the seed is sown, the moisture is first absorbed by the outer coats, which are everywhere furnished with sap and air-vessels; from these it is conveyed to the cuticle; from the cuticle it proceeds to the pulpy part of the lobes; when it has got thus far, it is taken up by the mouths of the small branches of the seminal root, and passes from one branch into another, till it is all collected into the main trunk, which communicates both with the plume and radicle, the two principal involved organs of the future plant. After this the sap or vegetable food runs in two opposite directions: part of it ascends into the plume, and promotes the growth and expansion of that organ; and part of it descends into the radicle, for nourishing and evolving the root and its various filaments. Thus the plume and radicle continue their progress in opposite directions till the plant arrives at maturity.

It is here worth remarking, that every plant is really possessed of two roots, both of which are contained in the seed. The plume and radicle, when the seed is first deposited in the earth, derive their nourishment from the seminal root; but afterwards, when the radicle begins to shoot out its filaments, and to absorb some moisture,

These dissimilar leaves defend the young plume from the injuries of the weather, and at the same time, by absorbing dew, air, &c. assist the tender radicle in nou rishing the plume, with which they have still a connection by means of the seminal root above described. But when the radicle or second root has descended deep enough into the earth, and has acquired a sufficient number of filaments or branches for absorbing as much aliment as is proper for the growth of the plume; then the seminal or dissimilar leaves, their utility being entirely superseded, begin to decay and fall off. Fig. 1. A, the foramen or hole in the bean through CCCCXX. which the radicle shoots into the soil.

Plate

fig. 1.

Fig. 2. A transverse section of the bean; the dots being the branches of the seminal root.

Fig. 2.

Figs. 6. 7. A, a transverse section of the radicle. B, Fig. 6. 7. a transverse section of the plume, showing the organs or vessels of the seminal root.

Fig. 8. The appearance of the radicle, plume, and se- Fig. 8. minal root, when a little further advanced in growth.

Having thus briefly described the seed, and traced its evolution into three principal organic parts, viz. the plume, radicle, and seminal leaves, we shall next take an anatomical view of the root, trunk, leaves, &c.

2. Of the root.] In examining the root of plants, the first thing that presents itself is the skin, which is of various colours in different plants. Every root, after it has arrived at a certain age, has a double skin. The first is coeval with the other parts, and exists in the seed: but afterwards there is a ring sent off from the bark, and forms a second skin; e. g. in the root of the dandelion, towards the end of May, the original or outer skin appears shrivelled, and is easily separated from the new one, which is fresher, and adheres more firmly to the bark. Perennial plants are supplied in this manner with a new skin every year; the outer one always falls off in the autumn and winter, and a new one is formed from the bark in the succeeding spring. The skin has numerous cells or vessels, and is a continuation of the parenchymatous part of the radicle. However, it does not consist solely of parenchyma; for the microscope shows that there are many tubular ligneous vessels interspersed through it.

When the skin is removed, the true cortical substance or bark appears, which is also a continuation of the parenchymatous part of the radicle, but greatly augmented. The bark is of very different sizes. In most trees it is exceeding thin in proportion to the wood and pith. On the other hand, in carrots, it is almost one-half of the semidiameter of the root; and, in dandelion, it is nearly twice as thick as the woody part.

The