Amsler electrically registering water current meter with case (c.1920). The propeller and vane are contained in the right hand compartment of the box. The device is in two parts which are fitted together for use. A battery would have been placed in the left hand compartment (see Image 4). Also contained in the left hand compartment is the electrical registering mechanism comprising a relay and switch operating a hammer which strikes a bell (see Image 5). When in use the number of bell-strikes is counted and converted into the value “t” (the interval of time in seconds between two consecutive signals: see Images 6 and 7) which further allows the flow rate to be calculated (in ft/sec and m/sec). It is presumed that each device is calibrated before use.
It was manufactured by Alfred J Amsler and Co, of Schaffhousen, Switzerland.
Alfred was the son of Jakob Amsler (or Amsler-Laffon) who invented the polar planimeter in 1854.