IN 



POTENTILLA 



POT-POURRI 



differentiation in any chosen direction riven the 

 force in that dint-lion. It U obvioua tnat other 

 directed quantities Id-aides forces may be expressible 

 the dilferrnliiil cnellii-icnui of a single non 

 directed or Malar quantity. Tim*, in the mathe- 

 matical theory of Hydrodynamics (q.v.) a very 

 iin|Hirtant distinction is made between motions 

 which have a velocity-potential and motions which 

 liave not. In the former the velocity can be re- 

 presented an a apace differentiation of a scalar 

 quantity : in the latter it cannot. See VoKTEX for 

 an account of fluid motion, which has no velocity- 

 potential. 



I'olcnlilla. a genus of plant* of the natural 

 order Rosace*-, sub-order Potentillc.-c, diMering from 

 Fragaria (StrawU-rry ) in the fruit having a dry 

 instead of a succulent receptacle. The species are 

 M-IV numerous, natives chiefly of northern tem- 

 perate regions, and some of them of the coldest 

 north: most of them perennial herbaceous plants, 

 with yellow, white, red, or purple flowers, and 

 pinnate, digitate, or ternate leaves. They are often 

 called Cinquefoil (Fr., 'live-leaved'); and some of 

 the species are favourite garden flowers. A few 

 are natives of Britain ; one of the rarest of which 

 is a shrubby species (P. fmticosa), forming a large 

 bush, with pinnate leave*, and a profusion of yellow 

 llowera, often planted in shrublieries. P. reptnns, 

 a common British species, with creeping stems, 

 digitate leaves, and yellow flowers, once had a 

 high reputation as a remedy for diarrhoea, from 

 the astringent property of its root, of which mo-t 

 of the species partake with it. But P. anxerina, 

 a very common British species, popularly known 

 as Silverweed, having creeping stems, yellow 

 Mowers, and pinnate leaves, which are beautifully 

 silky and silvery beneath, has an edible root, with 

 a taste somewhat like that of the parsnip. Swine 

 grub it up with avidity, and it wan once much 

 esteemed as an article of fond in some parte of 

 Scotland, particularly in the Hebrides, where it 

 abounds and has been a resource in times of famine. 

 The name potentilla is said to be derived from 

 the Latin //virus. ' powerful,' and to allude to medi- 

 cinal virtues now known to merit little regard. 

 TonnentU (q.v.) is sometimes referred to this 

 genus. 



Potenza (anc. Potentia), a town of South Italy, 

 ensconced in a valley of the Apennines, 103 miles 

 E. by 8. of Naples. It is surrounded by a wall, 

 has a fine cathedral, and disused fortifications. 

 Potenza was shaken by earthquakes in 1-273, liilU. 

 1812, and 1857. Pop. 17,978. The ttrovince of 

 Potenza, called Basilicata until 1871, has an area 

 of 3998 sq. in. and ( 1889) a pop. of 556,309. 



Pot-herbs are not, as might be supposed from 

 the name, the vegetables chiefly used for culinary 

 purposes, as supplying articles of food, but rather 

 those which are of secondary importance, and valu- 

 able chiefly for flavouring, as parsley, fennel, &c. 



Pot-holes. See GIANTS' KETTLES. 



Pot I. a seaport of Russian Caucasus, stands at 

 the month of the river Kion, on the eastern chore 

 of the Black Sea, 200 miles by rail \V. of Till is. 

 1 1 '-re maize (242,000), manganese (85,000), .Vc. 

 are shipped to the annual value of 366,000. The 

 import* do not exceed 2000. Poti was seized by 

 EtMbtalMB. Pop. 3112. 



l'li<l:rn. " Corinthian colony founded on the 

 westernmost isthmus of the Chalcidice jieninsula 

 in ancient Macedonia. By it* revolt from the 

 Athenian League (432 B.c. ) it brought on the 

 Peloponnesian war ; it wan besieged and taken by 

 the Athenians (429 n.r.). The Athenian colony 

 which wa then settled there was destroyed by 

 Philip of Macedon (356 B.C.). Cassander built 



up a new town, and called it Cassandria ; this 

 flourished greatly until it was captured and sacked 

 by the Huns. 



Pot-metal. Tan and |H>t metals are alloys of 

 copper and lead. The proportions of the two 

 metals vary from equal parte of each to 1 of copper 

 and 10 of lead. 



Poto'mac, a river of the United States, formed 

 by two branches which rise in the Allegheny 

 Mountains in West Virginia, and unite 15 miles 

 SK. of Cumberland, Maryland, from which point 

 the river flows in a generally south easterly course 

 400 miles, and falls into Chesapeake Bay, after 

 forming an estuary nearly 100 miles long, and 

 from 2J to 7 miles wide. The largest ships can 

 ascend to Washington, and the tide reaches George- 

 town. A few miles above Washington the river 

 forms a cataract 35 feet high ; and l>etween there and 

 Westportit falls more than 1000 feet. The scenery 

 in this portion of its course is wild and beautiful, 

 especially where it breaks through the Blue Kidge 

 at llaipei '.-, Ferry. Ite principal affluents are 

 the Shenandoah, Cacapon, and Monacacy. The 

 Potomac forms the greater part of the boundary 

 between Virginia and Maryland. 



Potoroo. or KANGAROO KAT(Hyytiprymnni), 

 a genus of marsupials, related to kangaroos. None 

 of the species are larger than rabbits. They feed 

 on roots, for which they dig with their fore-feet. 

 Two other genera, Bettongia and ^ipipryninus, are 

 nearly related. 



Potosf, capital of a department of the same 

 name, and one of the most famous mining-towns of 

 South America, stands in a dreary and barren 

 district, nearly 50 miles SW. of Chuquisaca. It is 

 built on the side of the Cerro de Potosi (15,381 

 feet), at an elevation of 13,000 feet above the sea, 

 and is thus one of the loftiest inhabited places on 

 the globe. The town has a circumference of some 

 4 miles ; but fully one-half is composed of tottering 

 and ruined buildings, uninhabited and desolate, 

 and the whole place, with its squalor, dilapidation, 

 and dirt, presents a sinister aspect. The public 

 buildings include a handsome cathedral and a 

 mint which employs 200 hands ; and the reservoirs 

 are also worthy of mention. The streets are steep 

 and narrow, and there are no wagons or carriages, 

 but only llamas and mules. The climate is very 

 trying : all the four seasons may lie experienced in 

 one day, but usually it is bitterly cold, owing to the 

 elevation and to the mountains all round, from 

 which the snow scarcely ever melts. Yet is Potosf 

 one of the principal commercial towns of Bolivia. 

 English and French manufactures are imported ; 

 and, as the country in the vicinity produces little 

 or nothing, all supplies have to be brought from a 

 distance. The industry of the place is limited to 

 silver-mining. The Cerro is still rich in this ore, 

 although the production, owing to the exhaustion 

 of the mines near the summit, and the frequent 

 inrush of water in those worked at a lower level, 

 has greatly fallen off. Potosj was founded in I MS, 

 and in 16H had 160,000 inhabitants. Ite population 

 does not now exceed 12,000. The ffforfiMMf, a 

 plateau country, rich in minerals and cattle, has an 

 area of 54,800 M}. in. and 11 pop. (IS92) of 360,400. 

 It is second in pop. of the Bolivian departments. 



Pot-pourri (Fr.), the name of a mixture of 

 sweet-seen ted materials, chiefly (lowers, dried, and 

 usually placed in a vase with a perforated lid, in 

 onler that their perfume may be diffused through 

 rooms in which it is placed. The principal ingre 

 dients are rose-petals, lavender flowers ami stalks. 

 violet*, jessamine-flowers, woodruff-leaves, doves, 

 orris- root, pimento, musk, sandalwood-rospings, 

 i shavings, \-c. But it also, and originally, 

 signifies a dish of different sorts of viands, nnd 



