DUERO (ilwil'r4). or DOURO ItIo'(-n't). large river of Spain and Portugal, rising in the Provinee of Soria fOld in an elevated region about 2.1 miles of the eily ut Soria I Nlap: Portugal, .\ 2t. It thor: at first southeast and south. pa-t Soria, reeeix' ing 1 he water. t f the Ifititerto, and then pur a general •ourse till it the l'ortilgtlese border. It then flows ft rming for about Go mile: the boundary bet \vecn Spain and Portugal, :titer which it due w•-st across Portugal, emptying into the .\tlantic not far south of Oporto. Its total length about 510 mile,. 11ter 113o mile.; of is in Portugal. The portion only is navigable. although upper course might lie utilized to -.one extent for trot pun (b,pite its swift, narrow •urrent.
mouth clo-ed by a bar and a number of which eon be passed by octal] going only (lurin• high tide. •I'lle tributa•it• of the Inter° are generally short. the greater number belonging to the Spanish ',mobil,. The
important are the Pisnerga, Volderaduey.
•rtia. and Tam•ga, on the right, and the Adaja, 'forme:, and .kgtteda on the left.
DUET (It. dui tin, from Lat. Ilion, twol. A. composition f(ir tw 11 with or without an ne•ompanintent of one or more In technical language, (hot is applied to a compo-sition for two \ or in strum•nts of the same kind, while ft no refer- to one for 1V11 or of different kinds. Duet: anc divided into three all of which, however. the form i- much the same. The dram at it duiI can of nt•ees,ity hare no fixed form, it vary ,cording 1.1 the dramatic -situation. sio„,t lesi is a splendid example of the c/ofrch dm. I, while the sung (1 to a of .\lend•bs-ohn follow the general idea of duets as originated in the teenth century and developed in the eighteenth by Stell'ani and.Clari.