POTENZA 



6294 



POTOMAC 



First, assume S to be connected to 

 slider a on P N. and with P through 

 R. Current from B will flow from 

 P to N, and, encountering resist- 

 ance in P N, will tend to divide and 

 shunt part of itself through G and 

 S to a. At the same time S tends 

 to send current in the opposite 

 direction, namely, from S to P. 

 Galvanometer G is deflected in one 

 direction or the other, according 

 as the E.M.F. of B or S predo- 

 minates. By sliding a along the 

 wire the two currents may be 

 brought into equilibrium, as will 

 be shown by G not being deflected. 

 Cell X is then balanced in like 

 manner against B by slider b, and 

 E.M.F. of X Pb 

 E.M.F. of S~ Pa 



The E.M.F. of S is known : there- 

 fore that of X can be calculated. 



Potenza. Prov. of S. Italy. It 

 is co-extensive with the comparti- 

 mento of Basilicata, and is bounded 

 N. by Foggia, S. by Cosenza, E. by 

 Lecce, and W. by Salerno. It has a 

 seaboard on the Gulf of Policastro 

 on the W. and the Gulf of Taranto 

 on the E. The land slopes gently 

 from the Apennines on the W., and 

 is well watered. The chief products 

 are cereals, wine, and oil. Its area 

 is 3,855 sq. m. Pop. 490,000. 



Potenza. City of Italy, capital 

 of the prov. of Potenza. It is pic- 

 turesquely placed on the E. de- 

 clivity of the Apennines, near the 

 source of the river Basiento, 103 m. 

 E. by S. of Naples. Surrounded by 

 medieval walls and fortifications at 

 an alt. of 2,700 ft., it has one of the 

 coolest climates in Italy. It has a 

 fine cathedral, built in the Doric 

 style. The city was almost de- 

 stroyed by an earthquake, 1857. 

 The old Roman town of Potentia 

 lay some 465 ft. lower down the 

 mountain side. Pop. 18,000. 



Potgieter, EVERHARDUS Jo- 

 HAKNES (1808-75). Dutch poet and 

 critic. Born at Zwolle, June 17, 

 1808, he worked in an Antwerp 

 business for some time, travelled 

 to Sweden, and, settling in Amster- 

 dam, issued, with Bakhuizen van 

 den Brink, a literary journal, 

 De Muzen, 1834-36. In 1837 he 

 founded De Gids, an able literary 

 periodical. His prose works in- 

 clude Het Noorden in Omtrekken 

 en Tafereelen, 1840; and his most 

 famous poem, Florence, appeared 

 in 1868. He translated several 

 English novels into Dutch, and 

 died at Amsterdam, Feb. 3, 1875. 



Pot Hole. Hollow in a river bed 

 which is deepened by the gyration 

 of accumulated stones by the 

 current. In soft rock these holes 

 often attain considerable size. In 

 a limestone region, after having 

 drilled a pot hole, the water often 

 reaches a marked plane of strati- 



Pot Hole in the Glacier Garden, Lucerne, seen from 

 above, showing the stone which has caused its formation 



fication, i.e. the division plane be- 

 tween two beds or strata of rock, 

 and along this it dissolves the rock, 

 in the course of time producing a 

 cave. Such limestone pot holes 

 become shafts or swallow holes, 

 down which the river disappears. 

 See Giant's Kettle. 



Poti. Seaport of Georgia, 

 Transcaucasia. It is in the dist., 

 and 60 m. W., of Kutais, and stands 

 where the Rion falls into the Black 

 Sea, and is a terminus of the Trans- 

 Caucasian railway. Its exports are 

 manganese, maize, and wheat. 

 Poti was ceded by Turkey to 

 Russia in 1829. It is the ancient 

 Phasis. Pop. 17,500. 



Potidaea. Town in Chalcidice, 

 ancient Macedonia. Although a 

 Corinthian colony, it was a member 

 of the Athenian confederacy, and 

 its revolt in 432 B.C. was one of the 

 causes of the Peloponnesian War. 

 After a two years' siege, it was taken 

 by the Athenians. In 356 it was 

 destroyed by Philip of Macedon. 



Potlatch (Chinook, from the 

 Nootka patshatl, a giving). Name 

 of a social custom prevalent among 

 the American Indians of the N. 

 Pacific coast. It consists in a 

 ceremonial giving of presents, the 



acceptance and 

 repayment of 

 which with inter- 

 est are compulsory. 

 It is often accom- 

 panied by the de- 

 struction of much 

 property by the 

 owner, who chal- 

 lenges another 

 man to do the 

 same or better. 



Pot Metal. 

 Name given to 

 glass that has been 

 coloured by addi- 

 tions of metallic 

 oxides. The glass 

 is coloured in the 

 melting-pot with 

 the oxides in contradistinction 

 from that which has only been 

 surface coloured. See Stained Glass. 

 Potomac. River of the U.S.A. 

 It is formed by the junction of two 

 branches, which rise in the N. of 

 West Virginia, and unite about 

 14 m. below Cumberland in Mary- 

 land. The main river follows a 

 general S.E. course of 365 m. 



Potosi, Bolivia. Old gateway through which Is seen 



the famous hill from which over 500,000,000 worth of 



silver has been extracted. Top, right, Plaza Pichincha, 



showing the cathedral and the Independence column 



and enters Chesa- 

 peake Bay by an 

 estuary from 2 m. 

 to 7 m. broad, and 

 nearly 80 m. long. 

 It forms a cata- 

 ract about 35 ft. 

 high, 1 5 m. a bove 

 Washington, a t 

 which city it be- 

 comes navigable. 

 The Shenandoah 

 is its largest tribu- 

 tary. There was 

 much fighting 

 around the river 

 during the Ameri- 

 can Civil War(g. v. ). 



