« PrécédentContinuer »
P. are a series of sonnets (often grossly indecent), the block of the next pulley, with the exception of La Beca du Dicomano (a parody of a pastoral poem the last cord, which passes round a lixed pulley by Lorenzo de' Medici); Confessione a la San Ver. | above, and is attached to the counterpoise P. The gine, a novel; and some letters.-- BERNARDO Pulci, tension of a string being the same in all its parts, elder brother of Luigi, wrote an elegy on the death the tension of every part of the string marked (1) of Simonetta, mistress of Julian de' Medici ; and a / in fig. 3 is that which is poem on the passion of Christ, and also executed produced by the weight of P, the first translation of the Eclogues of Virgil.-- consequently, as the last mov. LUCA Pulci, another brother, achieved some literary | able pulley is supported on reputation too by his Giostra di Lorenzo de' Medici, both sides by a string hav. a poem in honour of the success won by Lorenzo ing a tension P, the tension in a tournament; Il Ciriffo Calvaneo, à metrical applied in its support is 2P. romance of chivalry; Driadeo d'Ancore, a pastoral | The tension of the string
21 21 poem; and Epistole Eroiden
marked (2) is therefore 2P, PU'LEX. See FLEA.
and the second movable PULKO'VA, a village of Russia, in the govern. I equal to 4P. It may similarly
| pulley is supported by a force ment of St Petersburg, about 9 miles south of be shewn that the force the capital, contains a population of 600. It applied by the strings marked stands on a ridge called the Pulkova Hills, (4) in support of the last which command a splendid view of St Peters-Duilley (which is attached to burg, and is noted for its magnificent observatory, | W), is gP. Hence we see that Fig. 3. built by the Czar Nicholas, and placerl under the according to this arrangedirection of M. Otto Struve. For an interesting
ment, 1 lb. can support 4 lbs., if two movable pulleys description of the observatory, sea Professor o.
are used ; 8 lbs., if there are 3 movable pulleys ; 16 Piazzi Smyth's Three Cities in Russia (2 vols., lbs., if there are 4 movable pulleys; and if there aru Lond. 1862).
n movable pulleys, 1 lb. can support 21 lbs. It PU'LLEY, one of the Mechanical Powers (q. v.), must be noticed, hewever, that consists of a wheel, with a groove cut all round its in practice, the weight of the circumference, and movable on an axis ; the wheel, cords, and of the pulleys, and the U S which is commonly called a sheave, is often placed friction of the cord on the pulleys, inside a hollow oblong mass of wood called a blockmust be allowed for; and the fact, and to the sides of this block the extremities of the that in this system all of these
sheave's axle are fixed for sup. resist the action of the power P,
they are either fixed or movable. much more convenient in practice, PO
The fixed pulley (fig. 1) gives no and is modified according to the
mechanical advantage; it merely | purpose for which it is to be used ; fiw changes the direction in which a two prevalent forms are given in
force would naturally be applied figs. 4 and 5. In this system, one Fig. 1. to one more convenient--thus, string passes round all the pulleys,
W can be raised without lifting and as the tension in every part wi it directly by merely pulling P down. The single of it is that produced by the weight movable pulley, with parallel cords, gives a of P, the whole force applied to Fig. 4. mechanical advantage = 2 (fig. 2), for a little con elevate the lower block with its sideration will shew that as the weight, w, is attached weight, W, is the weight P multiplied
supported by two strings, the by the number of strings attached to the lower
string, which passes round C. in architecture, in dockyards, and T A P The fixed pulley, C, is only of on board ship, and various modi
service in changing the natu- fications of it-such as White's
able pulley are not parallel, found to answer best.—The third
there is a diminution of mecha- system (fig. 6) is merely the first
nical advantage-i.e., P must be system inverted, and it is a little more than half of W to produce an exact coun- more powerful, besides having the terpoise ; if the angle made by the strings is 120°, weight of the pulleys to support P must be equal to W; and if the angle be greater the power, instead of acting in than this, there is a mechanical disadvantage, or opposition to it, as in the former P must be greater than W. The following are case. By this time, it will have examples of different combinations of pulleys, gener- been evident to the reader that Fig. 5. ally known as the first, second, and third systems the mechanical advantage is not of pulleys. In the first system, one end of each cord produced by the pulleys, but by the strings, and is fastened to a fixed support above; each cord that the pulleys are merely useful in keeping the descends, l'asses round a pulley (to the lowest of strinys in a certain position, changing with as little which the weight, W, is fastened), and is fastened to friction as possible the direction of the pull, and
affording a convenient means of attaching the subjects. The pulpit (in Arabic, mimber) forma weight. Theoretically, the larger the number of
movable pulleys in one combin-
PULMONATA, an oriler of
former; water-snails, or pondW MAG snails (Limnca, Planorbis, &c.),
of the latter. Most of the P. Fig. 6. are protected by a shell ; in
some, as slugs, the shell is internal and rudimental.
PULNEYS, a range of hills in the Madura district of the Madras Presidency of India. The average height of this range is about 7500 feet above the level of the sea. It possesses peculiar advantages for the establishment of a sanitarium. The climate is one of the most equable anywhere to be found, the variation of the thermometer during twelve months in a closed room without a fire being observed to be
Pulpit (Fotheringhay, Northamptonshire, 1440 A. D.). no greater than between 58o and 62o. At present,
(From Parker's Glossary.) there are only a few European residences built on these hills.
one of the scanty appliances of Mohammedan
worship. PU'LO-PENA'NG. See PRINCE OF WALES' PULOU ISLAND.
and of the inhabitants of Central America, and PULP, a term employed to describe those very | soft and succulent parts of plants, almost exclu. of different species of Agave (q. v.), which is col. sively of fruits, which consist of cellular tissue lected by cutting out the Howering-stem from the with much juice. The pulp of a fruit is sometimes midst of the leaves in the beginning of its growth, found in one part of it, sometimes in another; and scooping a hole for the juice. From this cavity, thus, in the peach, plum, and other drupes, it is large quantities of juice are removed daily for the mesocarp ; in the prape and gooseberry, it is months. The juice is an agreeable drink when developed from the placentas, and the seeds are fresh, but is more generally used after fermentation, embedded in it.
when it has a very pleasant taste, but a putrid
smell, disgusting to those unaccustomed to it. PU'LPIT (Lat. pulpitum), an elevated tribune or Pulque is retailed in Mexico in open sheds called desk, from which sermons, lectures, and other solemn Pulquerias, which also serve for dancing-rooms. religious addresses are delivered. In great churches, Whin mixed with water and sugar, and allowed to the pulpit is commonly placed against the wall, or ferment for a few hours, it forms a beverage called in juxtaposition with a pillar or buttress. Originally | Tepache. A kind of spirit is also prepared from it. it would appear to have been used chiefly for the singing, chanting, or recitation which form part of
| PULSE (Lat. puls), a name for the edible seeds the public service, and was a kind of stage suffi
of leguminous plants, as corn is the name for the ciently large to accommodate two or even more
edible seeds of grasses. Peas and beans are the most chanters. For the convenience of the hearers, this
common and important of all kinds of pulse; next to stinge began to be used by the bishop, priest, or
them may be ranked kidney-beans, lentils, chick. deacon, for the delivery of the homily: and thus by peas, pigeon-peas, &c. Legumine (q. V.), a very degrees a tribune expressly suited to the latter use
nitrogenous principle, abounds in all kinds of pulse. alone came to be introduced. In some of the older Legumi
Legumine forms a thick coagulum with salts of churches, the ambo or pulpitum is still used for their
the lime, wherefore all kinds of pulse remain hard if chanting of the Gospel and Epistles. In Catolico
lie boiled in spring-water containing lime. The best churches, the pulpit is generally distinguished by
hv. kinds of pulse are very nutritious, but not easy of
!! some religious emblems, especially by the crucifix: digestion, and very apt to produce flatulence. and the pulpits of the Low Countries and of PULSE (Lat. pulsus, a pushing or beating). The Germany are often masterpieces of wood-carving, phenomenon known as the arterial pulse or arterial the preaching place in some of them forming part pulsation is due to the distention of the arteries conof a great artistic group, as of the Conversion of sequent upon the intermittent injection of blood into St Paul, the Vocation of Peter and Andrew, the their trunks, and the subsequent contraction which Teinptation of Adam and Eve, and other similar results from the elasticity of their walls. It is PULTOWA-PULU.
perceptible to the touch in all excepting very minute importance of ascertaining the various meanings of arteries, and in exposed positions, is visible to the eye. this symptom. “This pulsation,' says Dr Carpenter, "involves an The pulse is said to be full when the volume of augmentation of the capacity of that portion of the the pulsation is greater than usual, and it is called artery in which it is observed; and it would seem small or contracted under the opposite condition. to the touch as if this were chiefly effected by an A full pulse may depend upon general plethora, ou increase of diameter. It seems fully proved, how- a prolonged and forcible contraction of the left venever, that the increased capacity is chiefly given by tricle of the heart, and possibly, to a certain extent, the elongation of the artery, which is lifted from on relaxation of the arterial coats; while a small its bed at each pulsation, and when previously pulse results from general deficiency of blood, straight, becomes curved; the impression made upon from feeble action of the heart, from congestion of the finger by such displacement not being distin- the venous system, or from exposure to the action guishable from that which would result from the of cold. When very small, it is termed thread-like. dilatation of the tube in diameter. A very obvious | The tension of the pulse is the property by which example of this upheaval is seen in the prominent it resists compression, and may be regarded as temporal artery of an old person.'--Principles of synonymous with hardness. 'A hard pulse can Human Physiology, 4th ed., p. 492. The number of scarcely be stopped by any degree of pressure of pulsations is usually counted at the radial artery the finger. It occurs in many forms of inflamma. at the wrist, the advantages of that position being tion, and its presence is commonly regarded as one that the artery is very superficial at that spot, and of the best indications of the necessity of venethat it is easily compressed against the bone. In section. A soft or compressible pulse is indicative some cases, it is preferable to count the number of of general weakness. contractions of the heart itself.
| The strength of the pulse depends chiefly on the The qualities which are chiefly attended to in the force with which the blood is driven from the heart, pulse are its frequency, its regularity, its fulness, its but partly also upon the tonicity of the artery itself
and the volume of the blood. A strong pulse is The frequency of the pulse varies greatly with the correctly regarded as a sign of a vigorous state of age. In the foetus in utero, the pulsations vary. the system; it may, however, arise from hyper. from 140 to 150 in the minute; in the newly-born trophy of the left ventricle of the heart, and remain
to 115; from the 7th to the 14th year, from 80 to powers are failing. As strength of the pulse usually 90; from the 14th to the 21st year, from 75 to 85; indicates vigour, so weakness of the pulse indicates and from the 21st to the 60th year, 70 to 75. After debility. There may, however, be cases in which this period, the pulse is generally supposed to fall weakness of the pulse may occur in association with in frequency, but the most opposite assertions have undiminished energy of the system at large. For been made on this subject. There are many excep- example, active congestion of the lungs may so far tions to the preceding statement; young persons impede the passage of the blood through these being often met with having a pulse below 60, and organs that it cannot reach the heart in due quan. cases not unfrequertly occurring in which the pulse tity; the necessary result is a weak and feeble habitually reached 100, or did not exceed 40 in the pulse, which will rapidly increase in strength if minute, without apparent disease. The numbers the congestion is relieved by free blood-lettings. which have been given are taken from an equal Various expressive adjectives have been attached number of males and females, and the pulsations to special conditions of the pulse, into the consitaken in the sitting position. The influence of sex' deration of which our space will not permit us to is very considerable, especially in adult age, the enter. Thus, we read of the jerking pulse, the pulse of the adult female exceeding in frequency hobbling pulse, the corded pulse, the wiry pulse, that of the male of the same age by from 10 to 14 the thrilling pulse, the rebounding pulse, &c. beats in the minute. The effect of muscular exertion PULTOWA. See POLTAVA. in raising the pulse is well known; and it has been found by Dr Guy that posture materially influences
PU'LTUSK, a town of Poland, in the govern. the number of pulsations. Thus, in healthy males me
ment of Plock, is situated in a thickly-wooded of the mean age of 27 years, the average frequency
district on the Narew, 35 miles north-north-east of of the pulse was, when standing, 81, when sitting, Warsaw. It contains numerous churches and a 71. and when Iving. 66. per minute : while in very large bishop's palace. Pop. 4772. Here, on healthy females of the same age the averages were - 1
- December 26, 1806, was fought one of the battles standing, 91 ; sitting, 84: and lying, 79. During of the campaign of Eylau, between the Russians sleep, the pulse is usually considerably slower than an
hañ and the French. The field was most obstinately in the waking state. In disease (acute hydro- contested,
te hudra contested, but the victory, which, however, was cephalus, for example), the pulse may reach 150 or claimed by both armies, inclined in favour of the even 200 beats ; or, on the other hand (as in French. apoplexy and in certain organic affections of the I PU'LU, a beautiful substance, resembling fine heart), it may be as slow as between 30 and 20. silk, of a rich brown colour and satin lustre, used
Irregularity of the pulse is another condition largely as a styptic by the medical practitioners of
gular pulse : in one, the motions of the artery are for the same purpose. It consists of the fine hairs unequal in number and force, a few beats being from the stipes of one or more species of tree-fern, from time to time more rapid and feeble than the referrible, without doubt, to the genus Cibotium. rest; in the other variety, a pulsation is from time It was first imported into this country in 1844 to time entirely left out, constituting intermission from Owhyhee under the name of Pulu, or vegeof the pulse. These varieties often concur in the table silk, and was proposed as a substitute for same person, but they may exist independently of silk in the manufacture of hats, but could not be each other. Irregularity of the pulse is natural applied. In 1856, it was again imported from to some persons; in others, it is the mere result Singapore under the Malay names of Penghaof debility; but it may be caused by the most war Djainbi and Pakoe. Kidang, and was said to serious disorders, as by disease of the brain, or by have been used in Dutch pharmacy for a long period organic disease of the heart; and hence the practical as a styptic. Several importations have since taken
places and it has been successfully used. It acts action. Of these, as the most important, we shall mechauically by its great absorbent powers. describe in detail the following: 1. The Lift or PU’MA, or COUGAR (Felis concolor, Leopardus
Suction Pump; 2. The Lift and Force Pump; 3. concolor, or Puma concolor), one of the largest of The Chain-pump; 4. The Centrifugal Pump; 5. the American Felido, rivalled only by the jaguar.
The Jet-pump. It is sometimes called the American Lion, although
1. The Lift or Suction Pump.-The diagrams it is more allied to the leopard, notwithstanding
figs. 1 and 2 represent the ordinary suction pump. its want of spots and stripes. It is from 4 to 4
A is a cylinder, which is called the barrel ; with it is feet in length from the nose to the root of the tail,
connected at the bottom a pipe, B, which communi. and the tail about 2 feet or 21. The fur is thick
cates with the water to be raised ; and at its top is and close, reddish brown above, lighter on the sides, another pipe, C, which receives the water raised and reddish-white on the belly; the muzzle, chin,
In the barrel are placed two valves, D and E. Dis throat, and insides of the legs grayish-white, the
fixed in position at the bottom of the barrel; E is breast almost pure white. Young pumas have darkbrown spots in three rows on the back, and scattered markings elsewhere, exhibiting the relation to the leopards. The long tail of the P. is covered with thick fur, and is generally coiled up, as if it were prehensile, which it does not seem to be, although the P. climbs trees very well, and often descends on its prey from among their branches. The P. was formerly found in all except the coldest parts of America, but is now rare in most parts of North America, having been expelled by man. It rarely attacks man, but is very ready to prey on domestic animals, and seems to have a thirst for blood beyond that of other Felidæ, one P. having been known to kill 50 sheep in a night, drinking a little of the blood of each; a very sufficient reason for the anxiety which all American farmers shew for its destruction. Yet it is easily tamed, and when tamed, a very gentle creature, purring like a cat, and shewing equal love of attentions. The geographical range of the P. extends far southwards in Patagonia, and northwards even to the state of New York, although it is now very rare in all long-settled parts of North America. It is the Painter (Panther) of North American farmers. It sometimes issues from the forests, and roams over prairies and pampas, and is not unfrequently caught by the lasso of South American hunters. — A BLACK P. (Felis nigra of some naturalists), a doubtful species, and probably only a variety of the common P., is found in some parts of South America. PU’MICE, a mineral found in volcanic countries,
Fig. 1. generally with obsidian and porphyries. In chemical composition, it agrees with obsidian, of which
attached to, and forms part of the piston F, which it may be regarded as a peculiar form, rapidly
moves up and down the barrel when motive-power cooled from a melted and boiling state. It is of a
is applied to the rod G. The piston, or bucket, white or gray colour, more rarely yellow, brown,
consists of a cylindrical piece of wood or metal, or black; and so vesicular, that in mass, it is lighter than water, and swims in it. The vesicles,
which fits exactly the barrel in which it moves, or cells, are often of a much elongated shape. P.
so that no water or air can pass between its circum
ference and the sides of the cylinder. This tight often exhibits more or less of a filainentous
fitting is attained in wooden pistons by surrounding structure; and it is said to be most filamentous
them with a leather ring; and in those of metal, by when silica is most abundant in its composition. It is very hard and very brittle. It is much
| hemp or other packing, which is wrapped round a
groove made in their outer surface. The hollow used for polishing wood, ivory, metals, glass, slates,
interior of the piston is closed at the top by the marble, lithographic stones, &c., and in the pre
valve E, which is a kind of door opening on a hinge, paration of vellum, parchment, and some kinds of
at one side of it, in an upward direction, on tho leather. Among other purposes to which it is applied is the rubbing away of corns and callosities.
application of pressure, and shutting on to its seat
on the piston when the pressure is removed. When Great quantities are exported from the Lipari Isles
opened, water or air can pass through it to the to Britain and all parts of Europe. The Lipari
upper side of the piston; but when shut, none can Isles are in great part composed of P., which there,
pass from one side of the piston to the other. The as in some other places, occurs as a rock. P. is the
other valve, D, is similar to it in all respects, except chief product of some volcanic eruptions ; but in
that, as before stated, it is fixed in the bottom of some eruptions, none is produced. It is found also in
the barrel; it also can only open upwards. regions where there are now no active volcanoes, as at
To describe the action of the pump, we shall Andernach on the Rhine.
suppose the piston to be at the bottom of the barrel, PU’MPKIN. See GOURD.
and the pump to contain nothing but air. On PUMPS are machines for raising water and moving the piston up the barrel-the valve in it other fluids to a higher level. They are divided being shut, and kept so by the atmospheric pressure into several classes according to their mode of above it-no air can pass from above it into the