The viola (= German: Bratsche; French: alto) is the tenor of the modern violin family, with a range that extends a fifth below that of the violin and starts an octave above that of the cello. Violas are built in various sizes and were at one time used for both the alto and tenor registers. Experiments were made, starting in the later 19th century, to produce an instrument of sufficient size to provide the desired resonance while remaining small enough to be manageable, and more recently a larger instrument, played downwards like a cello and not held horizontally like a violin, has been devised. Violas take the tenor part in the string section of the modern orchestra and in string quartets, while the solo concerto and duo sonata repertoire of the instrument, starting in the early 18th century, has been considerably enlarged in the 20th.