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GALT

731

GALVANOMETER

of insect attacks the root, another leaf, flower or stem. Of insects that cause galls may be mentioned gall-flies, certain caterpillars, a few beetles, certain mites and scale-insects. Eggs are laid in the tissues of the growing plant, and generally the galls appear to form after the egg hatches.

Gait, a town of 9,718 in western Ontario, is called the Manchester of Canada. Grand River flows through it, supplying efficient water-power. Its leading lines of manufacture are machinery of all kinds, edged tools, woolen and knitted goods and flour. The thriving towns of Pans, Ayr, Preston and Hespler are near, and are reached by trolley. It took its name from John Gait, the Scotch novelist, who gave two noteworthy sons to the service of the Dominion.

Gait, Sir Alexander T., was born at Chelsea, England in 1817, educated in England, came to Canada and settled in Montreal. A government director of the Grand Trunk Railway in 1857—8, he proposed resolutions in the Canadian Parliament in favor of a federal union of British North America colonies in 1858. These resolutions became the basis of the policy of the government which he joined that year under Sir George E. Cartier. With Sir George E. Cartier and the Hon. John Ross he went as a delegate to England to urge the imperial government to sanction federation and the construction of the Intercolonial Railway; was minister of finance from 1858 to 1862, and a second time from 1864 to 1866. He was a delegate to Washington respecting the renewal of the reciprocity treaty, 1866-7, and was a member of the fisheries commission appointed under the treaty of Washington which sat at Halifax in 1877. He conducted negotiations on behalf of Canada for a commercial treaty with France and Spain, 1879, and was High Commissioner for Canada in England, 1880 to 1883. He is styled one of the fathers of federation.

Gal'ton, Francis, an eminent English scientist, was born near Birmingham in 1822. He graduated from Trinity College, Cambridge, in 1844. He travelled in 1846— 1847 in the Sudan, and in 1850 entered upon a thorough exploration of part of the southwest of Africa. On his return to England Gaiton published the narrative of his explorations. He next turned his attention to meteorology; and to him are due both the theory of cyclones and anticyclones and the device of weather-maps. Gaiton is greatest as a student of human heredity. In his English Men of Science, Hereditary Genius, Inquiries into Human Faculties, History of Twins etc. he made studies, some of them quantitative, which led him to set the greatest emphasis upon heredity and to attribute less importance to ordinary differences in nurture than was previously-

done. He also published two papers on finger-prints. Gaiton has made the methods of statistics and the questionnaire popular among modern scientific students

Galuppi (ga-lodp'pe), Baldassare (1706-1784). Italian composer of operas and harpsichord-music; chapel-master at St. Mark's, Venice, and director of the In-curabili, one of the four renowned conservatories of Venice. Robert Browning has introduced him in his poem, A Toccata of Galuppi's.

Galvani (gdl-va'n§), Luigi, an Italian surgeon, distinguished especially for his electrical discoveries He was born at Bologna on Sept. 9, 1737, and died on Dec. 4, 1798. From 1775 he was professor of anatomy in Bologna In 1780 he observed that frogs' legs, when skinned and supported on hooks of two different metals in contact, begin to twitch. He recognized in this the electrical effect of a battery composed of two metals and the moist frogs' legs. In ^ 1786 he studied the effect of atmospheric electricity in stimulating the nerves of the frog's leg. The frog's leg, thus used, is indeed the earliest .galvanometer of which we have any account.

Gal'vanom'eter, an electrical instrument, employed to detect the presence of an electrical current and sometimes to measure the intensity of the current. More than nine tenths of all the galvanometers in use depend upon the fact that a conductor conveying an electric current is surrounded by a magnetic field. (See ELECTRICITY.) Up to the last quarter of the i9th century currents were very frequently measured by their electrolytic effects and sometimes by their heating effects. Edison has devised a commercial current-meter which measures the current by measuring the amount of zinc which the current will remove from one zinc-electrode and deposit on another. Major Garden has invented a galvanometer for measuring electromotive forces, which depends upon the fact that the larger the current the hotter and longer the conductor. But these two instruments are not widely used. Galvanometers of the magnetic type are of two different kinds. In one the conductor is bent into a circular coil of wire, in the middle of which is suspended a small magnet. The magnet, when not acted upon by any moment of force, will set itself in the plane of the earth's magnetic meridian or in the direction of any artificial field which may be placed about it. If a current be passed through the coil of wire which has been placed in the plane of the magnetic field, the magnetic field will be changed and the suspended magnet will turn on its axis, thus indicating the presence of the current. This form of instrument has been brought to great perfection through the efforts of Lord Kelvin and, later, of