PUP 



PUT 



mersed inthewatertoacertaindeptfi : 

 ifthe piston frame be now thrust down 

 by the handle at G, the piston will 

 descend, and the water be forced by 

 its upward pressure tiirou^h the valve 

 C, so as to maintain the same level 

 in the pump as in the well. But when 

 the piston frame is elevated, the valve 

 C will shut (as shown in the figure), 

 and the water above C be lifted up 

 with the piston, and forced through 

 the valve M into the branch, M N, from 

 which its return will be prevented by 

 the shutting of the valve M when the 

 piston descends. 



" In each of these different kinds 

 of pumps wliich have been described, 

 the total effort required to work the 

 machine, independently of friction, is 

 equal to the weight of a column of 

 water, tlie base of which is equal to 

 the area of a section of the working 

 barrel, and the altitude equal to the 

 distance between the surface of the 

 water in the reservoir and the point 

 to which it is raised. In the suck- 

 ing pump the whole of this effort is 

 expended in raising the piston ; in 

 the forcing pump one part is expend- 

 ed in raising and the other in de- 

 pressing the piston, and it is advan- 

 tageous to dispose the machinery so 

 that these two parts shall be nearly 

 equal. In small purnps for domestic 

 purposes, the strength of man is usu- i 

 ally employed as the moving power ; i 

 but in raising water from great depths, [ 

 as the bottom of mines, the steam- i 

 engine is applied to this purpose." — { 

 {Brande's Encyclopirdia.) 



PU.MPKIX. Citcurbila pcpo. The ' 

 best varieties are the family, mam- 

 moth, Connecticut field, white bell, 

 Valparaiso. They are cultivated like 

 melons, but may be planted m corn- 

 fields. They are kept during the j 

 winter by placing them on shelves in i 

 a cellar where the temperature is 

 uniform and not below the freezing ' 

 point. They form admirable food for 

 stock, and are extensively employed 

 in the West to fatten hogs. 



PUNCHEON. A measure of 84 

 gallons ; a short post. 



PUNCTATE. Dotted. 



PUPA. A nymph, grub, or chrysalis, i 



I PUPIPARES, PUPIPARA. Those 

 insects are said to be pupiparoua 

 j which produce their young iu tiie con- 

 dition of a pupa or nymph, as the for- 

 est fiy {Hippobosca rquma). 



PUPIVORES, PUPIVORA. The 

 name of a tribe of hymeuopterous in- 

 ; sects, comprehending those of which 

 { the larvae live parasitically in the in- 

 terior of the larvaj and pupa3 of oth- 

 er insects. 



i PURGATIVES. Medicines which 

 produce purging. See Pliarmacopaia. 

 1 PURGING. Often used for diar- 

 I rhoea or over-purging. See the ani- 

 mals respectively. 



PURIFORM. Like pus. 



PURLINE. In building, a piece 

 of timber lying on the principal raft- 

 ers to support them in the middle. 



PURPURIC ACID. A red com- 

 pound produced by the action of nitric 

 acid on uric acid. 



PURSIVENESS, PURS I NESS. 

 Shortness of breath. 



PURSLANE. Portidacca olcra- 

 cea. An annual with succulent leaves, 

 partially cultivated as a salad and 

 pot-herb. 



PUS, MATTER. A yellow, cream- 

 like fluid formed in abscesses and 

 from wounds. It contains globules, 

 and is blood modified by inflammato- 

 ry action. 



PUTAMEN. The shell of a fruit. 

 The endocarp. 



PUT LOGS 

 in scaffolding. 



PUTREFACTION. The foetid de- 

 composition of animal and vegetable 

 substances containing much nitrogen. 

 The bad odours are due to the for- 

 mation of compounds of sulphur and 

 ammonia with sulphuretted hydro- 

 gen. Putrefaction can only take place 

 when oxygen is present with moist- 

 ure, and a temperature above 33° 

 Fahrenheit. Everything which hin- 

 ders the accom()lishment of these 

 conditions hinders putrefaction, as 

 drying, salting, coldness, placing in 

 air-tight vessels. Saline substances 

 hinder putrefaction by either coagu- 

 lating and changing the nitrogen com- 

 pound, or withdrawing the water by 

 their greater affinity. 



647 



Short timbers used 



