Horizontal limnigraph, Sarasin type. Belonged to De Marchi. Around 1910.

The limnigraph is a hydrometrographe recording the water level variations in lakes. The limnigraph in figure is a portable horizontal unit built in the first decade of the last century according to the prototype of the Swiss hydrologist E. Sarasin, dating back to 1879. It is housed in a wooden box to be placed on a pier. A float, now lost, drove a pulley attached to a shaft coming out from the back of the box. The pulley rotation caused by the movement of the float determine the horizontal displacement of a pen. The water level change is recorded on a paper tape, along with the time elapsed. The paper advancement is achieved with a clockwork mechanism.