Sulla realizzazione di due pendoli a breve periodo per sismografi orizzontali e verticali ad amplificazione ottico-galvanometrica

There are described two short period pendulums for horizontal- and vertical- component seismographs (electromagnetic and optical magnification) of the Galitzin type. In this first paper there are explained the rules to follow for an easy construction of the pendufuins and for the performance of the seismograpliical unities for a time already in function in some Itahan Stations.