GUÉRET, a town of central France, capital of the department of Creuse, situated on a mountain declivity 48 m. N.E. of Limoges on the Orleans railway. Pop. (1906), town, 6042; commune (including troops, &c.), 8058. Apart from the Hôtel des Monneyroux (used as prefecture), a picturesque mansion of the 15th and 16th centuries, with mansard roofs and mullioned windows, Guéret has little architectural interest. It is the seat of a prefect and a court of assizes, and has a tribunal of first instance, a chamber of commerce and lycées and training colleges, for both sexes. The industries include brewing, saw-milling, leather-making and the manufacture of basket-work and wooden shoes, and there is trade in agricultural produce and cattle. Guéret grew up round an abbey founded in the 7th century, and in later times became the capital of the district of Marche.
GUEREZA, the native name of a long-tailed, black and white Abyssinian monkey, Colobus guereza (or C. abyssinicus), characterized by the white hairs forming a long pendent mantle. Other east African monkeys with a similar type of colouring, which, together with the wholly black west African C. satanas, collectively constitute the subgenus Guereza, may be included under the same title; and the name may be further extended to embrace all the African thumbless monkeys of the genus Colobus. These monkeys are the African representatives of the Indo-Malay langurs (Semnopithecus), with which they agree in their slender build, long limbs and tail, and complex stomachs, although differing by the rudimentary thumb. The members of the subgenus Guereza present a transition from a wholly black animal (C. satanas) to one (C. caudatus) in which the sides of the face are white, and the whole flanks, as well as the tail, clothed with a long fringe of pure white hairs.
GUERICKE, HEINRICH ERNST FERDINAND (1803-1878), German theologian, was born at Wettin in Saxony on the 25th of February 1803 and studied theology at Halle, where he was appointed professor in 1829. He greatly disliked the union between the Lutheran and the Reformed churches, which had been accomplished by the Prussian government in 1817, and in 1833 he definitely threw in his lot with the Old Lutherans. In 1835 he lost his professorship, but he regained it in 1840. Among his works were a Life of August Hermann Francke (1827, Eng. trans. 1837), Church History (1833, Eng. trans. by W. T. Shedd, New York, 1857-1863), Allgemeine christliche Symbolik (1839). In 1840 he helped to found the Zeitschrift für die gesammte lutherische Theologie und Kirche, and he died at Halle on the 4th of February 1878.
GUERICKE, OTTO VON (1602-1686), German experimental philosopher, was born at Magdeburg, in Prussian Saxony, on the 20th of November 1602. Having studied law at Leipzig, Helmstadt and Jena, and mathematics, especially geometry and mechanics, at Leiden, he visited France and England, and in 1636 became engineer-in-chief at Erfurt. In 1627 he was elected alderman of Magdeburg, and in 1646 mayor of that city and a magistrate of Brandenburg. His leisure was devoted to scientific pursuits, especially in pneumatics. Incited by the discoveries of Galileo, Pascal and Torricelli, he attempted the creation of a vacuum. He began by experimenting with a pump on water placed in a barrel, but found that when the water was drawn off the air permeated the wood. He then took a globe of copper fitted with pump and stopcock, and discovered that he could pump out air as well as water. Thus he became the inventor of the air-pump (1650). He illustrated his discovery before the emperor Ferdinand III. at the imperial diet which assembled at Regensburg in 1654, by the experiment of the “Magdeburg hemispheres.” Taking two hollow hemispheres of copper, the edges of which fitted nicely together, he exhausted the air from between them by means of his pump, and it is recorded that thirty horses, fifteen back to back, were unable to pull them asunder until the air was readmitted. Besides investigating other phenomena connected with a vacuum, he constructed an electrical machine which depended on the excitation of a rotating ball of sulphur; and he made successful researches in astronomy, predicting the periodicity of the return of comets. In 1681 he gave up office, and retired to Hamburg, where he died on the 11th of May 1686.
His principal observations are given in his work, Experimenta nova, ut vocant, Magdeburgica de vacuo spatio (Amsterdam, 1672). He is also the author of a Geschichte der Belagerung und Eroberung von Magdeburg. See F. W. Hoffmann, Otto von Guericke (Magdeburg, 1874).