CONCH. 249 CONCIERGERIE. "Xatural .History of Kcoiioiniu Mollusks of the Uuiteil States," Uitilcd l^lates Fisli Cominissiou liutlclin fur JSS'J. CON'CHA, Josii GlTIKRRKZ he la. ilAlil^l es i)E LA Haba.na (ISOn-'J.j). A Spanish soldier aiMj statesnuui, born at t'iJrdol)a. Argentina. Shortly after the deatli of his father he went abroad and entered the Spanisli Army, in which he was rapidly j)romoted. He was CaptaintJen- eral of the Basijue Provinces (1843-40), and three times ('a])tain-(ieneral of Cuba < 1849-52, ■ lS.54-.i9. and 1874-7.")). in whieh latter capacity he was charged with complicity in the slave- trade. He was made Senator in I8G0. and suc- cessivelv held the positions of Minister to France (1862)," Minister of War (1863), and president of the Senate (1864-68). During the alisenee of (^)ueen Isabella in France, he was appointed i)V her the successor of Gonzales Bravo as presi- dent of the Council. Sc|itemher. 1868. but was immediately forced to resign, by the outbreak of the revolution which ended in the fall of the monarchy. CONCHA, JIaxi EL Gutierrez de la, Mar- QVE.s DEL DuERO (1S08-74). A Spani.sh general, brother of the preceding, who served against Don Carlos. He was promoted to the rank of field- niarshal in 1840, and in 1841 joined in the re- volt against the regency of Espartero. As Cap- tain-General of Catalonia, in 184.5. he suppressed, within a fortnight, an uprising of that province against conscri])tion. Two years later, in com- mand of the army .sent to Portugal, he skillfully adjusted the dis])ute between the two countries without bloodshed, and was created JIarques del Duero. With O'Donnell and others he petitioned (}ueen Isabella in 18.53 for a liberal government and the immediate convocation of the Cortes. He as thereupon banished to the Canary Islands, and fled from there to France, but on the dow^l- fall of Narvaez. in the following year, returned to S))ain and was reinstated in all his dignities. In the Revolution of 18(i8 he supported Isabella, and was placed in conuuand of the troojis in ilad- rid. The cause of the Bourbons, however, seeming hopeless, he contented himself with preserving order until the arrival of the victorious Revo- lutionary army under Serrano, to whom he re- linquished the comiviand. He then lived abroad until appointed commander of the Northern Army in the last Carlist war, when he con- tributed materially to the relief of Bilbao. On June 28. 1874, he was killed at the head of his troops in the assault on the Carlist stronghold of Estella. CONCHOID (kon'koid) (Gk. KoyxoeiSr/c, kon- choriiJi'a, nnissel-shaped, from '.oyvTj. l:oiwhf, shell + eJrhc, eidos. form) OF NIC'OME'DES. A 'shell-shaped' curve invented by Xicomedes (B.C. 180). It is related to the problems of tri- secting an angle (see Trlsection Problem), of constructing two geometric means betw'een two given straight lines, and of duplicating the cube. The curve may be constructed by drawing a straight line I.il for the directrix, and through any point P as the pole drawing a pencil of lines cutting LM in R,, R, The conchoid is the locus of points found by laying olT a constant length each way from R,. R... . . . on these rays. This constant length is called the modulus. The curve differs in general shape according as the niodulus is equal to, greater than, or less than the distance of the lixcd point from the fixed straight line. The figure shows the forms of the ciiive in the last two eases. The loop occurs when the modulus is greater than the perpendicu- lar distance of P and LM. When the modulus equals this distance. P is a cusp on the curve. The directrix LJJ is an asymptote to the two branches of the curve. If the foot of the per- pendicular from the pole to the directrix be taken as the origin, and the distance be called b, and the modulus «, the equation of the conchoid is il/ + b)-((r — !/-) — x'y' = 0. Its order is the fourth, and its class the sixth unless P is a cusp, in which case its class is the fifth. (See Curves.) P is, in general, a double point, and the cune meets its a.symptote at four consecu- tive points at infinity. The curve may easily be described mechanically, and is frequently used in architecture as a bounding line of the vertical section of cohunns. Con.sult: Sundara Row, Geometric Paper Foldinr/ (Chicago, 1901); Klein, Tortruge iiher annrieiriililtc Fmfjen der Elemciitarr/eometric (Leipzig, 1895), translated as Famous Problems of Geometry (Boston, 1897). CONCHOLOGY, kon-kol'd-ji. See Mollusca. CONCHOS, kAn'chos, Rio (connected with Sp.. Lat. eoiietiri. shell). A river in ilexieo, in the State of Chihuahua, rising on the southern border of the east of the Sierra iladre, flowing in a noi'therly direction through the rice table- land of that region, and joining the Rio Grande del Norte at Presidio del Norte after a course of about 3.50 miles (Map: Mexico, G 3). It re- ceives a numbei of confluents from the west, but no important tributary from the east. CONCIERGE, kux'syarzh' (Fr., doorkeeper). The French title of the janitor of an apartment- house. He is an im|)ortant functionary in the life of most Frencl) .ind Geiman cities; he sits in his little office by the main entrance and exercises a certain supervision over all those who pass in or out. opening the door to those who enter after a certain hour of the night (in Vienna as early as 10 o'clock). CONCIERGERIE, k(5N'syar'zh"re'.LA. A Paris |)rison. famous as the place of confinement of political prisoners during the French Revolu- tion. It forms a part of the Palais de .Justice toward the river, and was originally the resi- dence of the concierge of the old palacc> Among the famous prisoners confined in the Conciergerie and taken thence to the guillotine were ^lalesher- bes, ^ladame Roland. Danton. Desmoulins, and Robespierre. Here Marie . toinette was con- fined before her execution, in a small cell, afterwards changed tinto a chaiiel. In 1S40
