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PLYMOUTH-POACHING

ing-place of the Pilgrim Fathers Dec. 21, 1620. The rock on which they landed is covered with a granite canopy; a monument to their memory was dedicated 1889. Pop., 1890, 7,314.

Plymouth. Seaport and borough of Devonshire, at the head of P. Sound; prominent in the naval history of England. It is a very important naval station, has manufactures, and a

large commerce.

Citadel Gate.

The citadel, at the eastern extremity of the Hoe, is a fine example of the fortifications built during the latter half of the 17th century. Pop., 1891, 87,307. Plymouth Brethren. Denomination organized in Dublin 1827; premillennian and anti-ecclesiastical. Their leader was J. N. Darby, 1800-1882.

Plymouth Sound. Inlet of the English Channel on s. w. coast of England, ab. 3 m. long and 4 m. wide.

Plympton, GEORGE WASHINGTON, b. 1827. Prof. Brooklyn Polytechnic Institute 1863; Cooper Union 1869; ed. Van Nostrand's Magazine, 1870-86. The Blowpipe, 1870; The Aneroid, 1880.

Pneumatic Caisson. See CAISSON.

vacuum.

Pneumatic Dispatch. Method of transmitting papers or merchandise through tubes by compressed air, first suggested by Denis Papin 1687. In 1853 a London telegraph station and the Stock Exchange were connected by a tube 14 in. diameter, 660 ft. long, round boxes being carried by a partial In 1858 compressed air was used in one direction and a partial vacuum in the other. The London Post-office uses a lead pipe 24 in. diameter, inclosed in an iron pipe, with an air pressure of 10 lbs. and a vacuum of 6 lbs., attaining a speed of 1,000 yds. a minute and 3,000 yds. in 5 minutes. A parcel dispatch from a railroad station to the post-office in London was established 1863, a tube 2 ft. 8 in. square, 1,800 ft. long, with wheeled carriages moving at the rate of 17 m. per hour being used. In 1872 two tubes 4 ft. by 4 ft. 6 in., 14,214 ft. long, were laid there for the same purpose to the General Postoffice. In Philadelphia, 1893, the Post-office Department laid an iron pipe 6 in. diameter, ab. 3,000 ft. long; both pressure and vacuum are used. The pipes connecting the New York and Brooklyn post-offices will be 8 in. diameter, and those connecting with the sub-offices will be 8 in. and 10 in. The Western Union Telegraph Co. have had their offices connected by pneumatic dispatch tubes for many years, and in many mercantile establishments the cashier's office is connected with the salesrooms in the same manner.

Pneumatic Duct. See DUCTUS PNEUMATICUS.

Pneumatic Dynamite Gun. Long barreled cast-iron gun, whose projectiles are loaded with dynamite or explosive gelatin and are fired by pneumatic pressures, not exceeding 1,500 lbs. per sq. in. The necessary accessories are boilers and compressors for compressing the air, reservoirs for storing it, and electric motors for elevating and traversing the gun. D. M. Mefford of Ohio first applied this principle to a 2-in., 28-ft. and Cant. E. L. Zalinski, U.S.A., demonstrated in 1884 throwing dynamite loaded

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U. S. Government recently established two batteries of the guns; one of one 8-in. and two 15-in. guns at Sandy Hook, N. Harbor, and one of three 15-in. at Fort Winfield Scott, S Francisco Harbor. The 15-in. guns at Sandy Hook comma the main channel for a course of 9,000 yds. and the Swa Channel for 4,200 yds., and would have a vessel, going at miles an hour, under fire for 16 and 7 min. respectively. Ea gun could deliver 10 projectiles in the first case and 5 in t second. The 15-in. guns, firing charges of from 200 to 500 1 of explosive gelatin with great range and accuracy, oug really to be considered torpedo throwers, and as such have distinct value in coast defense works much beyond others this class.

Pneumatic Pile. Hollow cylinder which is sunk by t help of compressed air, and afterward is filled with concr and serves as a support for a superstructure. Depths of 60 may be reached by this method in soft soil.

Pneumatic Power. Compressed air in pipes for a pn matic clock system was introduced into Paris 1870, and sub quently extended to supply motors, a pressure of 90 lbs. sq. in. being maintained in 30 m. of pipe. In 1889 a simi system was established in Birmingham, Eng. Compressed for propelling tram-cars has been used in France since 18 There is a line from Vincennes 12 m. long, the air, under pr ure of 600 lbs. per sq. in., being carried in steel tanks bene the car. In New York city compressed air of 2,500 lbs. press is similarly employed on street cars.

Pneumatic Railway. One on which the cars are pelled by compressed air. In 1870 a line one block in len was built by Alfred Beach under Broadway, New York, diameter of the tunnel being 8 ft. In 1865 a railroad 600 long was laid in a brick tunnel 10 ft. by 9 ft. at Sydenh Eng., and the car was propelled this distance in 50 seco with an air pressure of 24 oz. per sq. in.; compressed and r fied air were used alternately.

Pneumatics. That subdivision of MECHANICS (q.v.) w treats of the action of forces upon air and other gases, disc ing their weight, friction, efflux, etc.

Pneumatic Syringe. See FIRE SYRINGE. Pneumatic Trough. Water tank, devised by Pries over which gases are collected in bell-jars.

Pneumatocyst. Air-chamber in a pneumatophore. Upright processes growing from Pneumatodes. roots of palms and some other trees and shrubs; suppos be organs of aëration.

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Pneumatophore.

Modified polyp of a Siphonop colony which buoys up or floats the hydrosoma. Pneumochlamyda (OPERCULATA). Section of Repto with the Pulmonates. including the Aciculida and Cyclostomida, sometimes cl

Pneumodermon. See GYMNOSOMATA.

Pneumo-Gastric Nerve. Tenth cranial nerve o anatomist, emerging from the base of the brain. It su the organs of the voice and of the respiration with both and sensory nervous energy; and the heart and stomach motor nerves alone. Its relation to respiratory, circula and digestive functions makes it one of the most impo nerves of the body.

mon.

Inflammation of the lungs. Phys

Pneumonia. a number of forms, one of which, the croupo distinguish lobar, is understood when the name is used alone. Th ease is now believed to be caused by one of several mic Some abnormal condition of the lung is necessa ganisms, the pneumococcus of Frankel being the most another factor, hence the disease occurs more frequen cold weather. There is a chill, followed by a high fever, similar causation it is self-limited, but is frequently respiration and pain on the affected side. Like all disea Domestic remedies are not to be relied upon, but anythin will assist to relieve the congested lungs, as hot foot-ba warm poultices to the chest will be helpful till the

comes.

Pneumonophora. See DIPNEUMONA and APODA.
Pnyx. Place of meeting for the popular assembly i
Its exact location is not known.

ens.

dr Po. River of n. Italy, heading in the Alps and flow into the head of the Adriatic Sea. Length 360 m., The volume of its water is great bu area 28,730 sq. m. able, necessitating levees along much of its course. Poaching. Unlawful destruction of game or fish

batteries of these Sandy Hook, N.I Winfield Scott, San dy Hook command ds. and the Seash vessel, going at respectively. Each case and 5 in t from 200 to 500 he nd accuracy, out nd as such have ch beyond others of

hich is sunk by the filled with concrete re. Depths of it

rin pipes for a peraris 1870, and subs essure of 90 lbs. per . In 1889 a similar ng. Compressed air n France since 1871 the air, under pres steel tanks beneath of 2,500 lbs. pressure

ich the cars are preone block in lengt dway, New York, t 365 a railroad 600 más by 9 ft. at Sydenhan istance in 50 seconds compressed and rare

LECHANICS (q.v.) wh d other gases, discuss

RINGE.

, devised by Priestley

rs.

pneumatophore.

es growing from and shrubs; supposed

yp of a Siphonopter drosoma.

. Section of Reptantis ida, sometimes classes

MATA.

h cranial nerve of the brain. It supp iration with both m heart and stomach respiratory, circular

of the most impor

the lungs. Physic which, the croupous is used alone. The one of several mere

el being the most c the lung is necessaryÁ curs more frequent ed by a high fever, side. Like all diseases but is frequently fat upon, but anything th ngs, as hot foot-bas helpful till the doc

MONA and APODA popular assembly in

the Alps and for Length 360 m., dra

water is great but

h of its course.

POCAHONTAS-POETRY

trespassing on another person's land or water in pursuit of
game or fish.

Pocahontas, ab.1595-1617. Daughter of the Indian Chief
Powhatan; protector of Capt. John Smith when about to be

Pocahontas.

executed; married to John Rolfe 1614; she left one son; ances-
tress of several Va. families.

Pocket. In Mining, small local accumulation of rich ore.
Pocock, EDWARD, D.D., 1604-1691. English Orientalist;
chaplain at Aleppo 1630-36, where he mastered Arabic; prof.
of Arabic at Oxford 1636, and of Hebrew 1648. He rendered
distinguished service in Biblical studies. Works, 1740.

Pococke, RICHARD, LL.D., 1704-1765. Traveler in Asia and Egypt; Archdeacon of Dublin 1745; Bp. of Ossory 1756, and of Meath 1765. Description of the East, 1743-45.

Pocomoke River. River rising in the Cypress Swamp
of Delaware, flowing s.w. into Chesapeake Bay; 70 m. long;
navigable for sloops 35 m.

Pocono. Thick Pa. sandstone, lying below the Pottsville.
See CARBONIFEROUS.

Pod. Seed-vessel which opens to emit the seeds; said to be
dehiscent.

Podactinaria. See LUCERNARIÆ.

Podaxonia. Phylum of Metazoa, including the classes
Sipunculoidea, Brachiopoda, and Polyzoa.

Podesta. Mediæval magistrate in n. Italian towns, often
practically a dictator.

Podesti, FRANCESCO, 1801-1895. Italian historical painter and sculptor. Siege of Ancona by Barbarossa; Francesca di Rimini; Judgment of Solomon.

Podetium. Stalk supporting the apothecium in lichens; also that of the sporanges in some hepaticæ.

Podiebrad, GEORGE, 1420-1471. Hussite leader; Regent of Bohemia 1453, King 1458; wise ruler who aimed to reconcile factions; excommunicated 1466; attacked by M. Corvinus of Hungary, whom he overcame.

Podocarpous. Fruit supported on a stalk above the

calyx.

Podogynium. See GYNOPHORE.

Podolia. Region of w. Russia, on the Austrian border.
Area 16,224 sq. m.

Podophthalma. See RHIPIDOGLOSSA.

Podophthalmata (PODOPHTHALMIA). Stalk-eyed Crustacea; division of Malacostraca, including the Thoracostraca; in a restricted sense only the Stomatopods and Decapods. Podophthalmite. Outer (distal) joint of the ophthalmite.

gonids.

1

23 genera and ab. 116 species, growing usually on sunken ro in swiftly flowing streams in tropical and temperate regio called the River-weed family.

Poduridæ. See THYSANURA.

Poc, EDGAR ALLAN, 1809-1849. Poet, romancer, and crit esteemed in France and Germany, if not also in England, t chief figure in American literature. His genius was strikin erratic, and lurid; his misfortunes were chiefly due to the fat deficiencies of his character. With rare gifts of fascinatio he had no love for truth, small sense of responsibility, small power of self-direction; hence his life was spent in shifts. hack-work, in vain projects, and often in bitter misery. H early volumes of verse appeared 1827-29-31; Narrative of A thur Gordon Pym, 1838; Tales of the Grotesque and Arabesqu 1840; Tales, 1845; The Raven, etc., 1845; Eureka, 1848. H critical work was that of a pioneer, and is now unimportan but his best poems, The Raven and The Bells, will live. H

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Poe, ORLANDO METCALFE, U.S.A., 1832-1895. U. S. Vols. 1862; chief engineer under Gen. Sherman. He did much work on rivers, harbors, and lighthouses.

Poëbrotherium. Generalized type of American Miocene animals, from which, through the Pliocene Procamelus, Cope traces the descent of the modern Camel.

cluding Limulus (King-Crabs). They have a broad horse-shoeshaped cephalothorax, an abdomen with five pairs of leaf-like Pacilopoda (XIPHOSURA). Group of Gigantostraca, inappendages, and a long movable caudal spine (telson). The six pairs of thoracic appendages are chelate and surround the mouth, which is centrally located, on the ventral side.

Pophaga, or MACROPODA. Tribe of diprotodont Marsupials, including the Halmaturide or KANGAROOS (q.v.). Macropus is the Great Kangaroo.

Poeppig, EDUARD, 1797-1868. writer on the Fauna and Flora of S. America 1835-45, and on Prof. Leipzig from 1833; the U. S. 1837.

Poerio, ALESSANDRO, 1802-1848. Italian patriot and lyric poet, killed in battle with the Austrians. Some of his songs were notable contributions to the cause.-His brother, CARLO, 1803-1867, endured repeated imprisonment at Naples, was deported 1858, and was a member of the parliaments of 1848 and 1860.

Poet Laureate. See LAUREATE, POET.

metrical shape. It has existed from the earliest ages, coniPoetry. Literature of imaginative character, usually in monly in some form of rhythm, and was often handed down orally. It constitutes an important part of every modern lit

Podosomata. Group of Arachnids, including the Pycno-erature, generally (except in the case of blank verse) in rhyme

Podosperm. See FUNICULES.

Podostemaceæ. Natural farily of flowering plants. of the class Angiosperma and

and under recognized metrical laws. Its main divisions are dramatic, epic, and lyric. If we look beyond externals

essence

1200

POEY-POITIERS

Poey, FELIPE, 1799-1894. Prof. Havana from 1842, the work of his chairs including zoology, botany, mineralogy, geology, and philosophy. Natural History of Cuba, 1851-60. His Synopsis Piscicum Cubensium, 1868-75, was purchased by the Spanish Government, and won praise in Europe.-His son, ANDRÉS, b. 1826, is noted chiefly as a meteorologist.

Prof. of

Poggendorf, JOHANN CHRISTIAN, 1796-1877. Physics at Berlin from 1834; ed. Annalen der Physik und Chimie from 1824; inventor of a multiplying galvanometer; writer on electricity and on the history and biography of science.

Poggio Bracciolini, GIAN FRANCESCO, 1380-1459. Italian historian, essayist, and satirist; secretary to Papal Court 1403-53; collector of classical MSS. Liber Facetiarum. Pogodin, MIKHAIL PETROVICH, 1800-1875. Russian historian, translator, and journalist; prof. Moscow 1830-44. The word Pogonias. See ACANTHOPTERI and DRUMFISH. Poh. In Africa, Arab game of MANCALA (q.v.). is mimetic, imitating the sound of a piece thrown upon the resonant board.

Pohl, JOHANN EMMANUEL, 1784-1834. Austrian botanist, in Brazil 1817-21; writer on its plants 1827-32.

Poikilothermic. Cold-blooded, i.e., having blood that varies in temperature with that of the external medium.

Poindexter, GEORGE, 1779-1853. M.C. from Miss. 1807-13; U. S. District Judge 1813-21; reviser of Miss. laws; U. S. Senator 1830-35; violent anti-federalist.

Poinsett, JOEL ROBERTS, LL.D.. 1779-1851. M.C. from S. C. 1821-25; U. S. Minister to Mexico 1825-29; Sec. of War 1837-41.

Point. Position considered without magnitude. Points moving under different laws may become coincident, yet each may have under its law a different tendency.

Point Alphabet. This consists of raised dots, variously grouped to represent letters and words, for the blind. New York alphabet and the Braille are used in U. S., the latter in Europe.

Pointed Arch. One whose intrados is formed by two arcs of circles intersecting at the crown; Gothic arch. Pointed Architecture. See GOTHIC.

Pointed Boxes. Rittinger hopper; piece of apparatus used in ore-dressing.

Pointer. Kind of dog closely related to the hound; introduced into England from Spain 1750 and crossed with the foxhound to produce the English variety. The pointer is very affectionate and intelligent. The habit of pointing the posi

under a head H, and K is a coefficient depending on the used and on the temperature.

Poison. Substance that uniformly works hurt to a ganism, even in a state of health, but not by mechanica tion. Poisons are found in the Animal (venom of sna Vegetable (strychnine), and Mineral (arsenic) kingdoms many instances, when administered in small doses, subst. classed as poisonous exert a beneficial action on certain eased conditions.-Poisons may be classified as follows: tant poisons irritate and inflame the tissues, inducing v ing, purging, and pains in the stomach and intestines: arsenious acid. Corrosives have a burning taste, attack perforate the tissues, and also have same effects as the tants; e.g., hydrochloric acid and caustic potash. Neu affect the nerves, brain, spinal marrow, and heart; ther four classes. Cerebral poisons affect the brain, producir sensibility and coma; e.g., morphine. Spinal poisons affe Ce spinal marrow, producing great sensibility and convul no stupor, but conscious till death; e.g., strychnine. heart, producing the combined symptoms of the two p spinal affect the brain and spinal marrow and indirect and heart, sometimes on the spinal marrow, reducing ing classes; e.g., aconitina. Cerebro-cardiac act upon the tions of the heart, paralyzing it, and also may affect the and spinal marrow; e.g., nicotine.

Poison Ivy. See Ivy, POISON.

Poison of Serpents. See SERPENTS, POISON OF.
Snakes. See PROTEROGLYPHA, SO
Poisonous
GLYPHA, and BITES.

For

Poisons, ANTIDOTES FOR. Vomiting should be pro by mustard and water or zinc sulphate and water. should be given, followed by milk. For alkalies dilute powdered magnesia, chalk or carbonate of soda in tepid gar or lemon juice is efficient. The antidote for cor sublimate is white of egg; for arsenious oxide, magnes iron peroxide in water; for tartar emetic, tannic acid gall nut or bark; for acetate of lead, magnesium sulpha opium, cold applications to the chest, electric stimulati coction of coffee, atropine subcutaneously, and exercise Mathematicia Poisson, SIMEON DENIS, 1781-1840. physicist; lecturer at the Paris Polytechnic 1802. Mec 1811-32; Theory of Probabilities, 1838.

DxV+ Dy3V + Poisson's Equation. V2V -475. It asserts that the potential function V, due distribution of matter, must be such that at all points the mass the value of V satisfies the above equation, the density at the point considered.

Poisson's Ratio. Ratio of proportional contrac extension when a prism or wire is stretched longitudina has been contended on the continent of Europe that th should be for all isotropic solids. Stokes has however that for India rubber this ought to be nearer than Thomson and Tait have shown that for cork it is mu than : so that isotropic bodies present no agreement value for Poisson's ratio.

Poissy, COLLOQUY OF. Sept. 1561, between French and 12 Huguenots led by Beza. It was followed by ot ferences, and in Jan. 1562 by an edict of partial tolerat

Poitiers. Ancient town of w. France, 61 m. s. o Near it Alaric was killed 507, Charles Martel overth

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Pointer Standing at Game.

tion of the game when scented was first taught, but is now
hereditary, as young pointers exhibit it. When scenting
game the pointer stops so suddenly that the forefoot remains
suspended in the air, when already lifted.

Points (NAUTICAL). Plaited ropes attached to the sails for
the purpose of reefing.

Points of the Compass. See COMPASS.

Poiret, JEAN LOUIS MARIE, 1755-1834. French botanist. Lecons de Flore, 1819-20; Histoire des plants de l'Europe, 1825-29.

Divine

Poiret, PIERRE, 1646-1719. French mystic, resident in Germany; editor of Mme. Guyon and Mlle. Bourignon. Economy, 1687, tr. 1713.

Poiseuille, JEAN LOUIS MARIE, 1799-1869. French physician and medical writer.

Poiseuille's Law.

Law of liquid flow through very
small tubes, investigated by Poiseuille. It is given briefly by
Kr4H
in which V is the volume of liquid
the equation, V=
1
a through a tube of radius r and length 1

Cathedral of Notre Dame, Poitiers.

defeated King John with 60,000, Sept. 19, 1356. Po Saracens 732, and Edward the Black Prince with ab.12 37,497.

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POITIERS-POLARISCOPE

Poitiers, DIANE DE, 1499-1566. Mistress of Henry II. of France 1547-59; Duchess of Valentinois 1548; all-powerful for a time.

Poitou. Former province of w. France, held by England 1152-1204, and several times later.

Poke, INDIAN. See HELLEBORE, FALSE.

Poker. Derived from the old card game of Primero or Prime, which was a favorite game in England ab.1500. In the 17th century a game called Post and Pair, derived from Primero, was played in w. England; from this came the game of Brag, of which the American game is simply a variation. It evidently arose in the custom of betting on the hands dealt in a round game, which itself was finally abandoned. The same process is now going on in Japan, where gamblers frequently do not play out the complicated native game of cards called 88. but win or lose according to their bets on the hands dealt. Straight Poker or Bluff originated in s. w. U. S. early in this century and was played with 20 cards, later with a full pack, the game depending on the five cards dealt. Draw Poker came later, the players having the privilege of drawing other cards in place of those dealt. Rank of the hands from the lowest upward: Pair; Two Pairs; Triplet; Straight, sequence of five not of same suit, not always played; Flush, five cards of same suit; Full, triplet and pair; Four of a kind; Straight Flush, sequence of five of same suit.

Poker Drawings. Designs burned upon wood with hot
pokers. John Cranch, 1751-1823, was noted in this line. Two
poker drawings by Salvator Rosa are said to be at Knowsley
Hall, Eng.

Pokeweed. Phytolacca decandra.
weed of the natural family Phytolaccaceae, the berries yielding
Coarse American
a crimson fluid; known as Scoke, Garget, and Pigeon-berry.

Pola. Ancient town of Istria, on the Adriatic, 54 m. s. of
Trieste: held by Venice 1148-1797; repeatedly destroyed; chief
naval station of Austria since 1848. It has a fine harbor, which
has been used in all ages. Pop., 1890, 39,273.

Polabians. Ancient Slavic race occupying the Lower Elbe. In a wider sense, used to designate all Slavonic peoples w. and n.w. of the Oder and Erzgebirge.

Poland. Formerly one of the largest and most powerful kingdoms in Europe, defender of Christendom against the Turks; named from the Polani, a Slavic tribe. Its history begins with Ziemovicz, second monarch of Piast dynasty, ab.850. Misceslas I., 962-992, accepted Christianity. Boleslas I., 9921025, enlarged the territory, and introduced beneficent institutions. An invasion of Mongols took place 1241. The first Diet assembled 1331. The Piast dynasty expired with Casimir III., 1333-1370. Lewis of Hungary succeeded; the Jagellon dynasty was founded by his son-in-law, who united Lithuania to P. 1386. Before 1500 P. extended from the Baltic to the Black Sea, including much of Prussia and Russia. The highest prosperity

too late, to make the monarchy hereditary. In 1763 F and Prussia presented S. Poniatowski to the Poles as their The insult was resented, but Russia fomented discord, fo her protection on the Conservative party. The Confeder of Bar declared war against Russia 1768. In 1772 Russia Austria divided among them 82,000 sq. m. of Polish terri The second partition followed a vain attempt at resist under J. A. Poniatowski and Kosciusko 1793; the third, after a general rising of the Poles, ending in the captu Warsaw, and the overthrow of the monarchy. Napoleo tablished the Duchy of Warsaw 1807, which was overth 1813. Repeated rebellions, especially in the portion subje Russia, have only brought further calamity upon the P A rearrangement of the division of P. was made by the gress of Vienna 1815. See WLADISLAS.

Poland, LUKE POTTER, 1815-1887. Judge of Vt. Supr Court 1848-60; Chief-justice 1860-65; U. S. Senator 1865-67: 1 1867-75 and 1883-85.

Poland China. See SWINE.

Polar Bands. Forms of cirrus clouds that are arran in apparently converging but really parallel lines, stretch across the sky.

Polar Bodies. See POLAR GLOBULES.

Polar Cells. See POLAR GLOBULES.

Polar Clock. The plane of polarization of sky light always 90° from the sun, and Wheatstone designed a clock pendent upon this which gives apparent solar time within few minutes.

Polar Current. Currents of air that flow from the po side toward the equatorial side of any locality, as the n winds of Europe.

Polar Distance OF A STAR. In the n. hemisphere, d tance from the North Pole of the heavens, measured on a gre circle of the celestial sphere.

Polar Exploration.
OCEAN, NORDENSKIOLD and PEARY.
See ARCTIC OCEAN, ANTARCT

In othe

Polar Globules. When an egg is ready to receive th spermatozoon or ready to develop into a new organism, th nucleus (germinal vesicle) divides, and one-half passes out a globule. In parthenogenetic eggs, the nucleus, left in th the animal pole, with a little of the yolk; this is the first pola egg, multiplies to form the cells of the embryo. eggs, which need to be fertilized by a spermatozoön, the pola globule first extruded may divide again, but the nucleus left i the egg always does so, and one-half is passed out as the secon polar globule. What is left in the yolk is the female-pronu cleus, which unites with the spermatozoon or male-pronucleu plication, produces the cells of the embryo. Weissmann be to form the segmentation nucleus of the egg, which, by multi lieves that several sorts of protoplasm are present while the egg is acquiring yolk, and what is no longer needed is passed out in the first globule, while the second is the equivalent of the spermatozoön. See SEX and PERIGENESIS.

Polarimeter. See POLARISCOPE.

Polaris. Star a-Ursa Minoris; second magnitude star, distant from the n. celestial pole 1° 17'.

Polariscope. Optical instrument for producing and analyzing polarized light. It consists essentially of a polarizer

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me, Poitiers.

Prince with ab.12 Sept. 19, 1356. Pop

Po.es of Volhynia.

was attained under Sigismund I. and II., 1506-72, the last of
the Jagellons. Two elements of weakness were now added to
the Constitution, the liberum veto, by which one member of
the Diet could stop legislation, and the law making the mon-
archy elective. Stephen Batory, 1575-86, warred successfully
with Russia. Under the weak Swedish rulers, 1586-1672, Polish
armies were still victorious for a time, but later P. was over-
run by enemies, and its territory was greatly reduced. War
with Turkey followed, and, after a disgraceful peace, was re-
newed under Sobieski, who routed the Turks at Choczim 1673.
The luxurious court of Augustus II. of Saxony, 1697-1733, had
a corrupting influence; his war with Charles XII. led to de-
pendence on Russia. Under Augustus III. it was attempted

Polariscope.

and an analyzer. In Malus' polariscope both are bundles of thin glass plates, one placed above

1202

POLARITY-POLICE

the analyzer: it may be turned around a vertical axis as well, the angle being read off on a horizontal circle. If the instrument be used for quantitative work, it may be called a polarimeter. See SACCHARIMETER.

Polarity. Phenomenon exhibited by some plants of placing their leaves in a n. and s. direction.

Polarization, OPTICAL. If the ether vibrations when transmitting a beam of radiant energy be brought into a single plane, the beam is said to be plane polarized. If a wave be propagated by the successive motions of a row of ether particles while each particle moves in a circle, the beam is said to be circularly polarized; again, if the path of each particle be an ellipse, we have elliptical polarization. Polarization may be DEXTROGYRATE or LÆVOGYRATE (q.v.). Light may be polarized; first, by reflecting it from glass or other reflecting surface, the polarization being greatest at a particular angle of incidence called the polarizing angle, which for glass is ab. 53°. The plane of reflection in which polarization takes place is called the plane of polarization. Second, by transmission through a pile of glass plates, the angle of incidence being the

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Biaxal Crystal; Black Cross changed to hyperbolas
by rotating the crystal.

Effect produced by passing polarized light through crystals.

polarizing angle. Third, by double refraction, the two rays be-
ing polarized in planes at right angles to each other. In the
case of tourmaline one of the rays, the ordinary, is absorbed
by the crystal so that the extraordinary ray alone emerges.
Certain transparent media have the power of rotating the
plane of polarization of a beam of light through a definite angle
when the beam is passed through them. This phenomenon is
called rotatory polarization. The amount of rotation varies
with the wave length, and is also proportional to the thickness
of the medium traversed. If this thickness be one millimeter,
then the angle of rotation for any particular color is called the
specific rotatory power of the medium. It may be DEXTRO-
ROTATORY or LAVOROTATORY (q.v.).

ELECTRICAL.-If two conducting plates be immersed in an
electrolyte, and a current of electricity be passed through for
a short time, the plates suffer a change in condition, in virtue
of which, if they now be joined by a wire, a current opposite
in direction to the original current will flow through the wire.
The electrodes in such a case are said to be polarized. This
effect is due to the deposition upon the plates or in contact
with them of substances of opposite polarity set free by the
current.

MAGNETIC.-A magnetized piece of iron or steel is said to be polarized, the centers of force being called the poles.

Polarizer. Any optical device for producing the polar ization of light. It is one of the essential parts of a polariscope. The instruments usually used as polarizers are a plane black glass mirror, a bundle of thin glass plates, or doubly reNICOL'S PRISM and TOURMALINE.

a

Polar Lights. See AURORA BOREALIS.

Polder. Land below the sea-level, which by drainage a Netherlands, where much of the country is of this nature. dikes has been reclaimed and put to use; important in

Pole. Point near the end of a magnet at which the ra netic force is greatest. See MAGNETISM.

Pole, REGINALD, 1500-1558. Cardinal 1536; papal legate see of York 1531, and been attainted 1536 for a book against England 1554; Abp. of Canterbury 1556. He had declined cousin, Henry VIII.

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Pole, SPHERICAL. The pole of any circle or circular arc the surface of a sphere or spheroid is the extremity of a dia eter of the sphere perpendicular to the plane of the circle. Treatise Pole, WILLIAM, Mus. Doc., F.R.S., F.R.S.E., b. 1814. lish engineer, musician and authority on whist. Iron, 1872; Life of Sir William Fairbairn, Bart., 1877; Lif Sir William Siemens, 1888; Philosophy of Music, 1879; Phil phy of Whist, 1883.

Pole-Cat. See FERRET.

Polemics. Religious controversy; department of theol long and earnestly cultivated by differing Christian churc sects, and schools of thought.

Polemon, 2d cent. B.C. Greek maker of itineraries, p ably useful to Pausanius.

Polemoniaceæ. Natural family of flowering plant the class Angiosperma, sub-class Dicotyledons, and s Gamopetala, comprising 10 genera and ab. 200 species of h mostly natives of America; called the Polemonium family Polenta. Paste, usually of corn meal, eaten in Italy salt, cheese, and sometimes meat.

Pole of Reference. In Polar Coördinates, fixed on the initial line about which the radius vector revolves is thus the vertex of the vectorial angle.

Pole Piece. Piece of soft iron attached to the pole magnet, of such size and shape as to concentrate or arr the lines of magnetic force to the best advantage. The pieces of a dynamo usually take the shape of the arma which is to rotate between them. Iron is used because high magnetic susceptibility.

Poles AND Polars. Points and lines in the plane conic, having certain reciprocal relations. The polar of point in reference to a given conic is a straight line, the of the intersections of pairs of tangents to the conic at where transversals from the given point cut the conic. given point is the pole. If the pole be without the coni polar is the chord of contact of tangents from the pole If the pole be on the conic, the polar is the tange the curve at the pole. If two points be so located tha second is on the polar of the first, the first will be on the of the second. Every point in the plane of a conic has its in reference to that conic; and every straight line its pole. conic to which any system of poles and polars refers auxiliary conic.

curve.

Poles, CELESTIAL. Points about which the celestial appears to revolve.

Poles OF THE ECLIPTIC. Points where the line draw pendicular to the ecliptic pierces the celestial sphere. P of North Pole, right ascension 18 h., declination 66° 33'. Pole-Star. See POLARIS.

Polevoi, NIKOLAI ALEXOCIEVICH, 1796-1846. Russian dramatist, and historian, b. in Siberia; ed. Moscow Tel 1825-35.-His son, PETER, is also an author.

Polian Vesicles. Little sacs connected with the c Police. The means used for the preservation of do oesophageal water ring of Starfishes and Sea Urchins. order, and civil regulation of inhabitants to enforce pea quiet, and promote the public health and security. The men are employed by towns and cities, under the direc a police committee or board. Constables are sometin are appointed by the Governor upon request for service pointed by the county courts, and in Pa. Coal and Iron corresponding districts. In most European countries th are a military organization; in Great Britain the Iris stabulary only are military in character. London has 16.000 men in the police force; St. Petersburg 10,000 8,000, and New York 4,000.

Police, MILITARY. Enlisted men of a company are who is held accountable for the cleanliness or police into squads, under the charge of a non-commissioned ters, barracks, bedding, bunks, arms, and accoute Provost guard is also a military police which, under ders of a provost-marshal, perform police duty wit limits where military authority prevails.

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