PULTUSK 



Pultusk. To\vn of Poland. It 

 stands on tbe Narev, in the govt., 

 and 35 in. N., of Warsaw. Its 

 trade and industries are incon- 

 siderable. The ancient castle was 

 formerly a residence of the bishop 

 of Plock. Pultusk was the scene 

 of the victory of Charles XII of 

 Sweden over the Saxons in 1703, 

 and of the French over the Rus- 

 sians, Dec. 26, 1806. Pop. 19,000. 



Puma (Felia concolor). Large 

 carnivorous mammal of the cat 

 family, widely distributed through 

 N. and S. America. It is easily re- 

 cognized by its size, the body 

 being nearly four feet long, and its 

 uniform and unspotted tawny 

 colour. Young animals are pro- 

 fusely spotted with black and 

 have ringed tails, but they assume 

 the colour of their parents when 

 about six months old. There are 

 several local varieties. 



In N. America the puma is com- 

 monly known as the mountain lion 

 or the panther, while in S. America 

 it is called the lion or cougar. 

 Native Indians call it " the friend 

 of the Christian," on account of its 

 harmlessness to man and its ten- 

 dency to accompany him ap- 

 parently out of curiosity. But it is 

 a dangerous foe to horses, cattle, 

 deer, and dogs, and does great 

 damage in the neighbourhood of 

 farms and cattle ranches. In the 

 forest regions it preys chiefly on 

 monkeys and rodents. It usually 

 spends the day in sleep, and roams 

 by night in search of prey, which it 

 kills by leaping on their backs and 

 breaking their necks. A puma has 

 been known to clear nearly 40 ft. 

 in a horizontal leap and 20 ft. in a 

 vertical one. It makes its lair in 

 cavities in the rocks, and usually 

 produces from two to four cubs in 

 a litter. In captivity it is usually 

 gentle and easily tamed. 



6398 



Pumice OR PUMICE STONE. In 

 geology, name given to an effusive 

 igneous rock possessing a spongy 

 texture. Grey in colour, it has 

 been formed by the expansion of 

 occluded moisture when the molten 

 rock reaches the surface. Pumice 

 stone is characteristic of lavas of 



rhyolitic composition, and is ex- 

 tensively used as a polishing, 

 smoothing, and cleaning stone. 

 Ground to a powder and mixed 

 with soaps, it forms a constituent 

 of many metal polishes. The finest 

 pumice stone is obtained from the 

 Lapari Islands. See Rhyolite. 



PUMPS: VARIETIES AND USES 



A. Williams, Editor, Engineering Wonders of tbe World 



A rticks which add to the information given herein include A irPump ; 

 Compressed Air ; Hydraulics; Sprengel Pump; Water Supply 



Suction 

 Pic 



ipo 



Fig. 1. Diagram 



showing principle 



of bucket pump. 



See text 



Puma. Male and female of Felis concolor, a large 

 American member of the cat tribe 



Oambitr Ballon P.Z.8. 



A pump is a machine used to 

 move fluids. Pumps may be divided 

 into four main classes according to 

 their working principles: (1) Re- 

 ciprocating pumps, which draw the 

 fluid in by suction and expel it by 

 the movement of a bucket, piston, 

 or plunger. (2) Rotating pumps, 

 without valves. (3) Pumps in 

 which steam, compressed air, or 

 gas acts di- 

 rectly on the 

 fluid. (4) 

 Mechanical 

 lifters, such 

 as chains 

 of buckets, 

 which dip in- 

 to the liquid. 

 Though the 

 pumps de- 

 scribed in this 

 article are of 

 the kinds 

 designed pri- 

 m a r i 1 y to 

 deal with 

 water and 

 other liquids, many of them differ 

 only in detail from pumps used for 

 air and gases 



RECIPROCATING PUMPS. These 

 may be subdivided into (a) bucket 

 or lift pumps; (b) piston or force 

 pumps; (c) combined bucket and 

 plunger pumps. 



The principle of 

 the bucket pump 

 is illustrated in 

 Fig. 1. When the 

 bucket is first 

 raised, a partial 

 vacuum is created 

 in the part of the 

 barrel below it, and 

 water rushes in 

 through the suc- 

 tion pipe, lifting 

 foot-valve A. 

 During the first 

 down.-stroke, the 

 water below the 

 bucket is trapped 

 by the closing of 

 A, presses open 

 b u c k e t- valve B, 

 and passes to the 

 upper side of it. 

 Meanwhile the 

 column of water 



Fig. 2. Surface 

 pump, work- 

 ing by suction 



vertical 



below B is prevented from falling, 

 because it is subjected to atmo- 

 spheric pressure atits lower end only. 



When the bucket 

 rises again, it car- 

 r i e s the water 

 above B with it, 

 and simultaneously 

 more water is 

 sucked into the 

 barrel .through A. 

 A bucket pump of 

 this kind is single- 

 acting, and dis- 

 charges water only 

 when the bucket 

 rises. Fig. 2 repre- 

 sents a surface 

 pump, which does 

 most of the raising 

 by suction. Theo- 

 retically a pump 

 should suck through 

 height of 34 ft. 



Where water has to be lifted 

 to great heights the pump barrel 

 may be continuous with a rising 

 main or delivery pipe of the same 

 or greater internal diameter, and 

 the pump rod work through the 

 main, in which case the bucket 

 can be drawn to the surface for re- 

 pairs ; or the top of the pump is 

 closed in as in Fig. 2, and the water 

 is delivered through a pipe con- 

 nected with the barrel at the top. 

 An extra valve is in some cases 

 fitted in the delivery to relieve the 

 main valves 

 and reduce 

 leakage when 

 the pump is 

 not working ; 

 and if the suc- 

 tion lift is con- 

 siderable a 

 valve may be 

 placed in the 

 suction pipe 

 just above 

 water to keep 

 the pipe full 

 and make starting-up easier. 



Fig. 3 is a section of a double- 

 acting Wilcox semi-rotary lifting 

 pump. The pump barrel is here 

 replaced by a circular casing, closed 

 at both sides. A diaphragm, 

 fixed on a central spindle passing 

 through one side to a handle, is 



Fig. 3. Double- 

 act ing Wilcox 

 semi-rotary liiting 

 pump. See text 



