O'HIGGINS 



5828 



OHMMETER 



Ambrosio O'Higgins, 

 S. American adminis- 

 trator 



portion is traversed by the Andes, 

 the surface sloping W. to the fer- 

 tile valley of Chile. The N. boun- 

 dary is partly traced by the river 

 Maipo, while the Rapel flows along 

 its S. frontier. The chief products 

 are wheat, wine, and fruit, and 

 cattle-rearing and gold-mining are 

 carried on. The capital is Ran- 

 cagua, 40 m. by rly. S. of Santiago. 

 Area, 2,168 sq. m. Pop. 97,000. 



O'Higgins, AMBROSIO (c. 1720- 

 1801). S. American administrator 

 and soldier. Of humble parentage, 

 he was sent 

 from Ireland 

 to his uncle, a 

 Jesuit in Se- 

 ville, who, 

 finding him 

 unsuited for 

 the Church, 

 dispatched him 

 to S. America. 

 Peddling as he 

 went, he made 

 his way across 

 the Andes to Chile and on to Lima, 

 where he kept a stall and trafficked 

 in mules. Driven thence by the In- 

 quisition, he returned to Santiago, 

 where he obtained a government 

 contract to build rest-houses on 

 the mountain roads. 



In 1770 Higgins was sent to 

 suppress a rising of the Arauca- 

 nian Indians, whom he defeated, 

 but he won their goodwill after 

 peace was concluded. He was 

 made intendent of Concepcidn in 

 1786, and two years later captain- 

 governor of Chile with the title of 

 marquis of Osorno. He governed 

 with an iron hand, repaired roads, 

 encouraged trade, and checked 

 official corruption. Promoted 

 viceroy of Peru in 1796, he thus 

 became the king of Spain's repre- 

 sentative in S. America. O'Higgins 

 was the first and greatest of the 

 many Irish who acquired fame in 

 S. America. He died Feb. 18, 1801. 

 O'Higgins, BERNARDO (1778- 

 1842). Chilean soldier and states- 

 man. Born at Chilian, Aug. 20, 

 1778, natural son of Ambrosio 

 O'Higgins, he was educated in Eng- 

 land, returning to his own country 

 in time to join the movement for in- 

 dependence. In 1813 he was made 

 commander-in-chief, and in 1817 

 dictator of the country, in which 

 capacity he 

 formally de- 

 clared its in- 

 dependence ot 

 Spain in 1818. 

 He then drove 

 out the Span- 

 ish troops and 

 set about or- 

 ganizing the 



goyer n m e n t Bernardo 0)HigginS! 

 ot the country. Chilean soldier 



He resigned in 1823, and lived in 

 retirement at Lima until his death, 

 Oct. 24, 1842. See The Independ- 

 ence of Chile, A. S. Chisholm, 1911. 



Ohio. River of the U.S.A. 

 Commercially the most important, 

 and, next to the Missouri, the 

 largest tributary of the Mississippi 

 river, the Ohio is formed by the 

 union of the Monongahela and the 

 Allegheny rivers at Pittsburg. It 

 flows generally S.W. for 975 m., 

 joins the Mississippi at Cairo, 

 and during its course separates 

 West Virginia and Kentucky from 

 Ohio, Indiana, and Illinois. It has 

 a breadth varying from rather less 

 than J m. to a little more than f m., 

 and drains an area exceeding 

 200,000 sq. m. Among its principal 

 affluents are the Tennessee, Cum- 

 berland, Wabash, Kentucky, Kan- 

 awha, and Big Sandy. In addition 

 to Pittsburg and Cairo, the towns 

 standing on its banks are Cincin- 

 nati, Paducah, Marietta, Louisville, 

 Evansville, and Mount Vernon. 



The Ohio, except for a short dis- 

 tance at Louisville, where there is a 

 fall of 26 ft. in 2 m., is navigable 

 for large vessels throughout its 

 length, although delay is caused 

 during drought periods by the low 

 level of the water, and at other 

 times by flood. A canal with locks 

 was constructed to overcome the 

 obstruction caused by the falls. See 

 The Ohio River, A. B. Hulbert, 1906. 



Ohio. North-central state of 

 the U.S.A. Its area is 41,040 sq. m., 

 or nearly one -third larger than 

 Scotland. The state is crossed from 

 N.E. to S.W. by a low hill ridge, 

 whence the surface slopes to Lake 

 Erie in the N. and to the Ohio river 

 in the S. The Maumee, flowing into 

 Lake Erie, is the chief northern 

 river ; the S. part of the state is 

 watered by many affluents of the 

 Ohio, which have cut deep valleys 

 through the sandstone rocks. 



Ohio produces large quantities of 

 maize, wheat, and oats, besides 

 tobacco, hay, potatoes, fruit, etc. ; 

 stock-raising is a valuable interest. 

 The coalfields comprise an area of 

 nearly 12,000 sq. m., and natural 

 gas, petroleum, limestone, and 

 other minerals are obtained. The 

 important manufactures include 

 iron and steel products, flour, and 

 rubber goods. The State, Ohio, and 

 Miami universities are among 

 higher educational institutions. 

 Besides the lake, river, and canal 

 facilities, 9,130 m. of steam and 

 4,050 m. of electric rlys. are avail- 

 able for transport. Two senators 

 and 22 representatives are sent to 

 Congress. Columbus is the capital 

 and Cleveland and Cincinnati the 

 largest cities. Ohio was admitted 

 to the Union in 1803. Pop. 

 5,759,000. See The Old North 



West, B. A. Hinsdale. 1899 ; Ohio, 

 S. S. Wilson, 1902; Ohio, R. 

 King, 1903. ^ 



Ohlau. Town 6f Upper Silesia. 

 It stands on the confluence of the 

 Ohle and the Oder, 16 m. S.E. of 

 Breslau. The buildings include a 

 castle and several churches. There 

 are tobacco and cigar factories ; 

 machinery and shoes are manu- 

 factured. It has also lime kilns and 

 a horse and cattle market. Ohlau 

 was made a town in 1290 and was 

 at one time a residence of the 

 Sobieski family. It became 

 Prussian with the rest of the 

 Silesian duchies in 1742, and after 

 the peace treaty of 1919 was in a 

 plebiscite area. Pop. 9,000. 



Ohligs. Town of Germany, in 

 the Rhine prov. of Prussia. It is a 

 rly. junction 16 m. N. of Cologne, 

 on the edge of the industrial area of 

 Westphalia, and has manufactures 

 of cutlery and other steel goods. 

 Pop. 21,000. 



Ohm. Unit of electrical resist- 

 ance. The resistance of a circuit is 

 1 ohm when a pressure of 1 volt is 

 required to cause a current-flow of 

 1 ampere. See Unit, Electrical. 



Ohmmeter. Apparatus for 

 measuring the electrical resistance 

 of a conductor in ohms or megohms. 



Ohmmeter. Diagrams illustrating 



types o! instruments for measuring 



electrical resistance. See text 



The Wheatstone bridge ascertains 

 the resistance of a conductor by 

 balancing it against a conductor of 

 known resistance. The arrange- 

 ment of parts is shown diagram- 

 matically in the illustration, 

 Fig. 1. Screw-posts abed are con- 

 nected by conductors a b, d b, of 

 equal resistance ; c and 6 by a 

 conductor which includes galvano- 

 meter G. An adjustable resistance 

 R is inserted in branch a c ; and the 

 conductor X to be tested in 

 branch d c. The parts a z, c y, c w, 

 d v have equal resistance. Current 

 flows from battery B to a, and 

 reaches d by alternative paths. 

 If the resistance of a c be greater 

 than that of c d, some of the 

 .current passing through a b will be 

 shunted through " bridge " b c and 

 c d, causing a deflection of the 

 needle of G. If X offers more 

 resistance than R, current reach- 

 ing c through R will be partly 

 shunted through c b and b d, and 

 deflect the galvanometer needle in 



