A Roman brass instrument second only to the tuba (see Tuba (ii)) in importance (it is classified as an Aerophone). It consisted of a long bronze tube, curved into a shape resembling the letter ‘G’, the lower extremity having a large detachable mouthpiece and the upper having a flared bell projecting forwards horizontally. It was held in a nearly vertical position while an ornamented wooden bar extended from top to bottom, serving both as a grip and as a strengthening member. To judge from pictorial representations, it had a circumference of about 3 metres (see illustration).
Like the Lituus it appears to have been of Etruscan origin and, also like that instrument, is said to have been a later modification of the tuba, the straight trumpet. This hypothesis is quite plausible in view of the priority of the tuba; but it must be reconciled with another widely held view: that the cornu was originally an animal's horn like the Buccina. Perhaps the cornu developed from the tuba, inspired both by the curved shape of the buccina and by the desire for a lower-pitched instrument of manageable design. Sources occasionally confuse cornu and buccina because their shapes were roughly similar, but there can be no doubt of their separate identities. From its earliest appearance in Etruscan pictorial sources, the cornu was much larger than the buccina, was fashioned of brass and had its distinctive vertical brace.
In Etruscan and early Roman times it appeared together with the tuba and lituus in processions on state occasions, particularly at funerals of important personages. With the expansion of the republic and the empire, however, it became more and more a military instrument, taking second place only to the tuba in this respect. It also appeared with some frequency in the arena with the hydraulis and occasionally in the cult of Cybele with the more common tibia, tympanum and cymbala.
For further illustrations see Tibia and Tuba (ii).
G. Fleischhauer: Etrurien und Rom, Musikgeschichte in Bildern, ii/5 (Leipzig, 1964, 2/1978)
G. Wille: Musica romana (Amsterdam, 1967)
R. Meucci: ‘Roman Military Instruments and the Lituus’, GSJ, xlii (1989), 85–97
JAMES W. McKINNON