The correct division of the notes and their accurate measurement is called metre; and their slowness or quickness, tempo. Although it is difficult to divide the notes according to a given tempo, it is not nearly so difficult as [determining] the correct tempo for a piece in the first place. More of this in its place.

We have two kinds of metre: duple and triple; these are either simple or compound. Duple time is when the bar can be divided into two equal parts; and triple is when it cannot. Simple duple time is either four crotchets or two crotchets. Four-four time is indicated by a latin C at the beginning of the system of staves after the clef; see x); it is also called common time, probably just as frequently as simple time. There is another time-signature which indicates four crotchets, and is denoted by a C with a line through it, see y). This time is called alla Breve or alla Capella, and goes as fast again as the normal crotchet beat, and is divided in two like the two-four time. It is used, for Fugues or fugue-like movements, but is not very suitable to the Galant style of composition. Through the ignorance of copyists, however, mistakes are often encountered, since they draw a line through the C where there should be none, or draw a line through every C.