3 - Mainka

Made in 1910 in Strasbourg.
It was in use in Strasbourg from 1910 to 1960.

• consists of a horizontal pendulum
  mass 450kg (990lb)
  period 8-10s
• mechanical amplification
• records on smoked paper

The Mainka is a large horizontal pendulum which records just one component. Two machines installed at right angles to each other are necessary in order to record all the horizontal movement of the ground. The pendulum is made of a mass of 450kg (990lb) suspended in such a way as to oscillate around an almost vertical axis. Damping is achieved by a plate soaked in a visquous liquid and situated between the amplification rods. The recording is on a roll of smoked paper connected to the ground.

Mainka made several models of horizontal pendulums with masses of 130, 400, 450 and 2000kg (286, 880, 990 and 4400lb respectively). The model on display in the museum was made by S.O.M., a highly specialised Parisian manufacturer of optical and mechanical equipment. The S.O.M. made some small changes in the original model, resulting in an averagely sensitive seismometer, strong, solid and above all, very easy to handle. For these reasons it was chosen in 1925 to equip French seismology stations and particularly the stations in French colonies.