This finely made timing device was powered by a heavy weight which hung down under the clockwork mechanism. The two dials indicated elapsed time in seconds and tenths of seconds. The mechanism was controlled by a pair of electromagnets which were mounted on the rear of the main clockwork timing gear box. The device was used to time short elapsed intervals in reation time experiments. It was manufactured by Royer Tavarger & Co., Neufchatel Suisse and carries number 20659.