Siphon pluviograph, belonged to De Marchi. First half of the last century. The pluviograph is a recording rain gauge used to gather and measure the amount of liquid precipitation over a set period of time. The outdoor part (lost) was a funnel of know surface collecting rain and conveying it to the measuring and recording unit (in the figure) kept inside the weather station. The rain filled a cylindrical container with a float inside that would rise with the progressive filling of the cylindrical container. The axis of the float was plugged a stylus which marked on a strip of paper the volume of rain fallen over time. The diagram was mounted on a rotating cylinder making a full revolution every 24 hours moved by a clockwork mechanism. When the cylindrical container was completely filled, it is immediately emptied by a siphon. The writing tip fell to the baseline and a new filling up of the cylindrical container begins