A later catalogue, dated 1912, offered a wide range of nearly a hundred different rulers, set squares and T squares made of wood, and then 20 models of slide rule of high quality and precision, made of pear wood (ideally suited to the task) with celluloid scales.
The favourable development since the early days was sadly interrupted by the Great War. The post-war depression and subsequent hyperinflation were very difficult times for the very specialized range produced in Geroldsgrün.
Slide rules were still unfamiliar to most people and used only by a limited circle of engineers and technicians, rarely by businessmen.
It was therefore not possible to introduce rationalized mass production. However, additional models for specific occupations and types of calculation were produced in collaboration with experts. There were now special-purpose slide rules for foresters and timber merchants and for reinforced concrete work.