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 augmentation of the capacity of that portion of the artery in which it is observed; and it would seem to the touch as if this were chiefly effected by an increase of diameter. It seems fully proved, however, that the increased capacity is chiefly given by the elongation of the artery, which is lifted from its bed at each pulsation, and when previously straight, becomes curved; the impression made upon the finger by such displacement not being distinguishable from that which would result from the dilatation of the tube in diameter. A very obvious example of this upheaval is seen in the prominent temporal artery of an old person.'-Principles of Human Physiology, 4th ed., p. 492. The number of pulsations is usually counted at the radial artery at the wrist, the advantages of that position being that the artery is very superficial at that spot, and that it is easily compressed against the bone. In some cases, it is preferable to count the number of contractions of the heart itself. The qualities which are chiefly attended to in the pulse are its frequency, its regularity, its fulness, its tension, and its force. The frequency of the pulse varies greatly with the age. In the foetus in utero, the pulsations vary from 140 to 150 in the minute; in the newly-born infant, from 130 to 140; in the 2d year, from 100 to 115; from the 7th to the 14th year, from 80 to 90; from the 14th to the 21st year, from 75 to 85; and from the 21st to the 60th year, 70 to 75. After this period, the pulse is generally supposed to fall in frequency, but the most opposite assertions have been made on this subject. There are many exceptions to the preceding statement; young persons being often met with having a pulse below 60, and cases not unfrequently occurring in which the pulse habitually reached 100, or did not exceed 40 in the minute, without apparent disease. The numbers which have been given are taken from an equal number of males and females, and the pulsations taken in the sitting position. The influence of sex is very considerable, especially in adult age, the pulse of the adult female exceeding in frequency that of the male of the same age by from 10 to 14 beats in the minute. The effect of muscular exertion in raising the pulse is well known; and it has been found by Dr Guy that posture materially influences the number of pulsations. Thus, in healthy males of the mean age of 27 years, the average frequency of the pulse was, when standing, 81, when sitting, 71, and when lying, 66, per minute; while in healthy females of the same age the averages werestanding, 91; sitting, 84; and lying, 79. During sleep, the pulse is usually considerably slower than in the waking state. In disease (acute hydrocephalus, for example), the pulse may reach 150 or even 200 beats; or, on the other hand (as in apoplexy and in certain organic affections of the heart), it may be as slow as between 30 and 20. The pulse is said to be full when the volume of the pulsation is greater than usual, and it is called small or contracted under the opposite condition. A full pulse may depend upon general plethora, on a prolonged and forcible contraction of the left ventricle of the heart, and possibly, to a certain extent, on relaxation of the arterial coats; while a smalĺ pulse results from general deficiency of blood, from feeble action of the heart, from congestion of the venous system, or from exposure to the action of cold. When very small, it is termed thread-like. The tension of the pulse is the property by which it resists compression, and may be regarded as synonymous with hardness. A hard pulse can scarcely be stopped by any degree of pressure of the finger. It occurs in many forms of inflamma tion, and its presence is commonly regarded as one of the best indications of the necessity of vene. section. A soft or compressible pulse is indicative of general weakness. The strength of the pulse depends chiefly on the force with which the blood is driven from the heart, but partly also upon the tonicity of the artery itself and the volume of the blood. A strong pulse is correctly regarded as a sign of a vigorous state of the system; it may, however, arise from hypertrophy of the left ventricle of the heart, and remain as a persistent symptom even when the general powers are failing. As strength of the pulse usually indicates vigour, so weakness of the pulse indicates debility. There may, however, be cases in which weakness of the pulse may occur in association with undiminished energy of the system at large. For example, active congestion of the lungs may so far impede the passage of the blood through these organs that it cannot reach the heart in due quantity; the necessary result is a weak and feeble pulse, which will rapidly increase in strength if the congestion is relieved by free blood-lettings. Various expressive adjectives have been attached to special conditions of the pulse, into the consideration of which our space will not permit us to enter. Thus, we read of the jerking pulse, the hobbling pulse, the corded pulse, the wiry pulse, the thrilling pulse, the rebounding pulse, &c. PULTOWA. See POLTAVA. PU'LTUSK, a town of Poland, in the govern ment of Plock, is situated in a thickly-wooded district on the Narew, 35 miles north-north-east of Warsaw. It contains numerous churches and a very large bishop's palace. Pop. 4772. Here, on December 26, 1806, was fought one of the battles of the campaign of Eylau, between the Russians The field was most obstinately and the French. contested, but the victory, which, however, was claimed by both armies, inclined in favour of the French. PU'LU, a beautiful substance, resembling fine 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 requiring notice. There are two varieties of irre- Holland, and lately introduced into this country 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 Djambi 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 PUMA-PUMPS. place, and it has been successfully used. It acts mechanically by its great absorbent powers. PU'MA, or COUGAR (Felis concolor, Leopardus concolor, or Puma concolor), one of the largest of the American Felida, rivalled only by the jaguar. It is sometimes called the American Lion, although it is more allied to the leopard, notwithstanding its want of spots and stripes. It is from 4 to 4 feet in length from the nose to the root of the tail, and the tail about 2 feet or 24. The fur is thick and close, reddish-brown above, lighter on the sides, and reddish-white on the belly; the muzzle, chin, throat, and insides of the legs grayish-white, the 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. rarely attacks man, but is very ready to prey on domestic animals, and seems to have a thirst for blood beyond that of other Felida, 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. 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. It It is PU'MICE, a mineral found in volcanic countries, generally with obsidian and porphyries. In chemical composition, it agrees with obsidian, of which it may be regarded as a peculiar form, rapidly cooled from a melted and boiling state. It is of a white or gray colour, more rarely yellow, brown, or black; and so vesicular, that in mass, it is lighter than water, and swims in it. The vesicles, or cells, are often of a much elongated shape. P. often exhibits more or less of a filamentous structure; and it is said to be most filamentous when silica is most abundant in its composition. It is very hard and very brittle. It is much used for polishing wood, ivory, metals, glass, slates, marble, lithographic stones, &c., and in the preparation of vellum, parchment, and some kinds of leather. Among other purposes to which it is applied is the rubbing away of corns and callosities, Great quantities are exported from the Lipari Isles to Britain and all parts of Europe. The Lipari Isles are in great part composed of P., which there, as in some other places, occurs as a rock. P. is the chief product of some volcanic eruptions; but in some eruptions, none is produced. It is found also in regions where there are now no active volcanoes, as at Andernach on the Rhine. PUMPKIN. See GOURD. PUMPS are machines for raising water and other fluids to a higher level. They are divided into several classes according to their mode of action. Of these, as the most important, we shall describe in detail the following: 1. The Lift or Suction Pump; 2. The Lift and Force Pump; 3. The Chain-pump; 4. The Centrifugal Pump; 5 The Jet-pump. 1. The Lift or Suction Pump.-The diagrams figs. 1 and 2 represent the ordinary suction pump. A is a cylinder, which is called the barrel; with it is connected at the bottom a pipe, B, which communicates with the water to be raised; and at its top is another pipe, C, which receives the water raised. In the barrel are placed two valves, D and E. Dis fixed in position at the bottom of the barrel; E is The hollow attached to, and forms part of the piston F, which moves up and down the barrel when motive-power is applied to the rod G. The piston, or bucket, consists of a cylindrical piece of wood or metal, which fits exactly the barrel in which it moves, so that no water or air can pass between its circumference and the sides of the cylinder. This tight fitting is attained in wooden pistons by surrounding them with a leather ring; and in those of metal, by hemp or other packing, which is wrapped round a interior of the piston is closed at the top by the groove made in their outer surface. valve E, which is a kind of door opening on a hinge, at one side of it, in an upward direction, on the application of pressure, and shutting on to its seat on the piston when the pressure is removed. When opened, water or air can pass through it to the upper side of the piston; but when shut, none can other valve, D, is similar to it in all respects, except pass from one side of the piston to the other. that, as before stated, it is fixed in the bottom of the barrel; it also can only open upwards. The To describe the action of the pump, we shall suppose the piston to be at the bottom of the barrel, and the pump to contain nothing but air. On moving the piston up the barrel-the valve in it being shut, and kept so by the atmospheric pressure above it-no air can pass from above it into the E PUMPS. 2. The Lift and Force Pump.-Figs. 3 and 4 represent two varieties of this pump. That shewn in fig. 3 is very similar to the suction-pump before described, with this exception, that the valve E B part of the barrel from which it is moving; the air relation between the power expended and the work contained in which becoming rarefied, by having to produced, as measured by the water raised-we occupy a greater space, exerts less pressure on the may remark, that the power is expended-1st, in valve D at the bottom of the barrel than the air in raising the water through the required height; 2d, suction-pipe B below it. This valve is thus opened, in overcoming the friction of the moving parts and the air from the suction-of the pump; 3d, in the friction and fluid resistance pipe enters the barrel; so of the water in passing through the valves and pipes; that when the piston has 4th, in the losses arising from the want of proper arrived at the top, a volume proportion between the various parts of the pump. of air equal to the contents The losses arising from these last sources are very of the barrel has passed great, and vary so much according to the confrom the suction-pipe into struction of each particular pump, that no useful the barrel. When the piston estimate can be formed of the efficiency. We may descends, it compresses the say, however, that a pump of this description, to air in the barrel, which shuts yield 50 per cent. of the applied power, must be the valve D; and when the well proportioned and carefully constructed. Cdensity of the compressed air becomes greater than that of the atmosphere, the valve E in the piston is forced open, and the air in the barrel passes to the upper side of the piston. The next upward stroke of the piston again draws a like quantity of air from the suction-pipe into the barrel; and, as none of this air again enters the pipe, but is passed to the upper side of the piston by its downward stroke, the suction-pipe is by degrees emptied of the air it contained. During this process, however, motion has taken place in the water at the foot of the suction-pipe. The surface of the water at H is pressed upon by the weight of the atmosphere with a pressure of about 15 lbs. on every square inch; and by the laws of fluidpressure, if an equal pressure is not exerted on the surface of the water in the suction-pipe, the water will rise in it, until the pressure on its surface, plus the weight of its fluid column, balances the pressure of the atmosphere on the surface H outside; so that, as the air in the suction-pipe is rarefied, the water rises in it, until, when all the air is extracted from it, the water stands at the level of the valve D. By the next upward stroke of the piston, the barrel being emptied of air, the water follows the piston, and fills the barrel as it filled the suction-pipe. The pressure produced by the downward stroke shuts the valve D, and forces the water in the barrel through the valve E. The succeeding upward stroke carries this water into the pipe above, and again fills the barrel from the suction-pipe. In like manner, every successive upward stroke discharges a body of water equal to the content of the barrel into the pipe above it, and the pump will draw water as long as the action of the piston is continued. D B Fig. 2. The action of this pump may be more shortly described by saying that the piston withdraws the air from the barrel, and produces a vacuum, into which the water rushes through the suction-pipe, impelled by the pressure of the atmosphere on its surface. This atmospheric pressure balances a column of water of about 33 feet in height; so that if the barrel be placed at a greater height than this from the surface of the water in the well, the water will not rise into it, and the pump will not draw. With regard to its efficiency-that is to say, the Fig. 3. Fig. 4. instead of being fixed on the piston, is placed in the discharge-pipe, the piston itself being solid. The water is drawn up into the barrel by suction in the manner just described in the suction-pipe, and then the pressure of the piston in its downward-stroke forces it through the valve E to any height that may be required. That shewn in fig. 4 is provided with a different description of piston, called the plunger-pole. Its action is precisely the same as that of the other, with this exception, that the plunger-pole, instead of emptying the barrel at every stroke, merely drives out that quantity which it displaces by its volume. It is simply a solid rod of metal, A, moving through a water-tight stuffingbox, B. This stuffing-box is made by placing, on a circular flange of metal, rings of india-rubber or other packing, the inner diameter of which is slightly less than that of the plunger-pole. On these is placed a ring of metal, and through the whole are passed bolts, which, on being screwed tight, force the packing tightly against the plungerpole. It possesses many advantages, for the packing can be tightened and repaired without removal of the piston or stoppage of the pump; also, the cylinder is not worn by its action, nor does it require to be accurately bored out, as in the other form of pump. In these pumps, it will be observed that the water is forced into the ascending pipe or column only on the downward stroke; it will thus be |