11 - Willmore

Made in 1950 in the United Kingdom.

• electromagnetic seismometer for field acquisitions
• the coil is fixed whereas the magnetic field is used as a mobil mass
  periode 1s
• used as horizontal or vertical seismometer
• amplificated by potentiometric bridges
• optical recording by means of a galvanometer.

It has been used in France for dams monitoring and especially during big seismic profile acquisitions from the 1960s.