422 ROOK ROOT tons of iron. The roof of the Grand Central station in New York is 652 ft. long and 200 ft wide, and consists of 32 wrought-iron trusses, rising in semicircular arches 94 ft. above the rails; the covering is of iron and glass; the trusses weigh 40 tons each ; the roof contains .80,000 sq. ft. of glass, and covers nearly three acres. See Rondelet, DArt de bdtir (Paris, 1812-'! 7); Ardant, Etudes sur lea charpentes d grande portee (Paris, 1837) ; Erny, Traite de la charpenterie (Paris, 1840) ; Ritter, Dach- und Bruektnconstruction (Hanover, 1869) ; Unwin, " Iron Bridges and Roofs " (London, 1869); Tredgold, "Carpentry" (3d ed., Lon- don, 1870) ; Matheson, " Bridges and Roof Structures" (London, 1871); Bow, "Econo- mics of Construction in relation to Framed Structures" (London, 1873); Stoney, "The- ory of Strains in Girders" (revised ed., Lon- don, 1873); D. H. Mahan, "Civil Engineer- ing" (revised ed., New York, 1873); and De Volson Wood, " Bridges and Roofs " (New York, 1873), and "Resistance of Materials" (revised ed., New York, 1875). ROOK, (corcutfrugilegut, Linn.), a bird of the crow family, about the size, form, and color of the common crow, from which it differs principally in having the base of the bill cov- ered with a rough scabrous skin, whitish in old birds. It is about 20 in. long and 40 in. in alar extent, the bill 2 in. ; the female is a little smaller ; the color is black, with purple, green- ish, and bluish reflections 1 , the feathers of the neck blended, and on the fore part of the head abraded ; the head is entirely feathered in the young; albinos sometimes occur, and the bill is often variously distorted. It is found over most of Europe, and abundantly in many parts of Great Britain. Rooks live in society all the year round, building their nests, seeking food, and roosting in flocks; their resorts, called rookeries, are often very extensive, one near tfeyii Rook (Corvus fhijrilegus). Edinburgh in 1847 containing 2,660 nests and about 80,000 inhabitants of all ages. The nests are made on tall trees, often in the midst of populous towns, and the same are used year after year ; they are fond of the groves of old family mansions, where they are protected. They are very early risers, going in search of worms in the fields or of garbage in the streets; they sometimes visit the beaches and flats in search of shellfish and crustaceans; they eat also grain, seeds, insects, nuts, and lizards, but rarely if ever carrion ; they plunder the grain fields only when forced by hunger; they feed with birds of various families without quarrel- ling. They prefer open fields, placing a senti- nel, and flying off at his alarm note with great noise ; the flight is generally by slow and reg- ular flappings, without undulations ; they often go many miles in search of food, and if they return in the forenoon or early afternoon, a storm within 24 hours may be confidently ex- pected. They begin to repair their nests early in spring, and lay four or five eggs, light green- ish blue, spotted and clouded with grayish brown and light purplish gray ; the young are hatched about the middle of April, and leave the nest by May 20; great numbers of the newly fledged birds are annually shot to be eaten. The rook has been taught to imitate the sounds of animals, but is less intelligent and docile than the raven, crow, and jackdaw. ROOKE, Sir George, an English admiral, born at the family seat near Canterbury in 1650, died there, Jan. 24, 1709. He entered the navy as a volunteer, and was made rear admiral of the red by William III. In the battle off Cape La Hogue, May 19, 1692, between the combined English and Dutch fleets and the French fleet, he led a night attack in the boats of the squad- ron, and burned six French three-deckers and seven other ships of the line, with a loss of only 10 men. He received a pension of 1,000, and was knighted. He was twice elected to parliament, and on the accession of Queen Anne in 1702 he was constituted " vice admiral and lieutenant of the admiralty of England, as also lieutenant of the fleets and seas." The war of the Spanish succession having begun, he was sent with a fleet against Cadiz, an at- tack upon which place was made, but aban- doned ; but receiving intelligence that the Plate fleet, under convoy of a French squadron, had taken shelter in the port of Vigo, in con- cert with the duke of Ormond he stormed the town, and destroyed 17 ships, capturing specie and goods amounting in value to 1,000,000. In August, 1704, he was conspicuous in the capture of Gibraltar. After a whole day's battle with a large French fleet off Malaga, Aug. 24, which got away in the night, he re- turned to England and retired from service. ROOKS, a N. W. county of Kansas, inter- sected by the S. fork of Solomon river ; area, 900 sq. in. It is not included in the census of 1870. The surface is gently rolling, and con- sists chiefly of prairies. ROOT, in botany. See PLANT, vol. xiii., p. 576. ROOT, in mathematics, a term used in two different though related senses. I. In arith- metic a root is the inverse of a power ; thu 16 is the fourth power of 2, and 2 is the fourth
