Translation into English by Lord Gifford of Treatise on Thorough Base, a work concerning the theory of music, by Domenico Quadri. 'The treatise covers the rudiments of music, including clefs, keys, chord structures etc. (using a 19th-century approach), rather than thorough bass in the 18th-century sense' (Cooper).
According to the Oxford English Dictionary, thoroughbass is 'a base part extending through a piece of music, and written by itself, with figures indicating the chords or harmonies to be played with it; a figured bass, basso continuo; esp. (formerly) an accompaniment thus written or played; hence loosely, an accompaniment in general. Also, the method of indicating harmonies by a figured bass, or the art of playing from it; loosely, the science of harmony in general.'