Summary The contribution of the Antwerp mathematician and instrument maker Michiel Coignet to the development of the sector is investigated. It will be shown that he invented a rule, the reigle platte, which he later used in conjunction with Mordente's reduction compass, thus in effect performing the same operations as with a sector. Later Coignet transferred the scales to the legs of the compass thereby making his first sector, which bore a resemblance to the reduction compass.

In this paper I present a picture of the social status of the Antwerp arithmetic teachers. This requires first a closer look at the Antwerp schoolmaster in general. Because no fewer than two-thirds of them were also reckoning masters most of the conclusions about teachers are also valid for reckoning masters. The consequences of the sack of Antwerp in 1585 provides us with a wealth of information about the social position of its inhabitants. The material about reckoning teachers is presented. (...) Especially important, in this period of religious turmoil and civil war, is the information concerning the religious convictions of reckoning masters. Finally, a closer look is given to the contents of the arithmetic books and the introduction of arabic numerals. (shrink)