'Millionär' calculator, Hans W. Egli Rechenmaschine-Fabrik, Zurich, c.1910
Inv. V10361

Seventeenth and eighteenth-century adding machines could not do much more than add and subtract. In the nineteenth century machines appeared which could also multiply, although in fact this amounted to repeated addition. The 'Millionär', which went into production in 1899, could multiply directly and that produced a huge saving in time. Particularly in carrying out complex calculations with large numbers this large and quite pricey apparatus was very useful.This specimen was used for astronomical calculations at the Leiden Observatory. Another Millionär was used in 1918 to calculate the effect on water levels of a dam to be built in the Zuiderzee. The calculations showed that such an enclosing dam would not have any negative effect, and that prediction has proved correct down to the present day.