Feuerwerkbuch (mid 15th century)

One effect of the introduction of communal clocks was that city ordinances began to specify the end of the working day for certain professions, the beginnings of court sessions, the sale of merchandise at markets, and so on. By the middle of the fifteenth century one finds clock-time regulations in the statutes of urban schools, which delimit the duration of daily classes and fix the work time of teachers. Mechanical time-keeping also contributed to the use of sandglasses – calibrated for specific intervals such as hours or quarter-hours – as tools for measuring or limiting the duration of various activities, e.g., meetings, speeches, cooking, work breaks or production processes. The image shows an illustration from a mid-fifteenth century copy of the so-called Feuerwerkbuch depicting work at a gunpowder mill. The hourglass on the wall was there either to regulate the work process shown (pouncing) or to coordinate work shifts. Besides leading to the introduction of shifts, the greater measurability of the hour also facilitated a change from daily to hourly wage, which begins to emerge in the fifteenth century in the form of overtime payments or deductions for missed hours.

Commentary. Philipp Nothaft (May-June 2019)