AbstractAn instrument called the“Ice Gauge”, for checking and measuring the vertical movements of an ice surface, has been constructed under the supervision of AB Hydroconsult, Uppsala, Sweden. With this self- recording instrument it is possible to synchronize the movements of the ice with the water-surface fluctuations. This instrument thus gives the basic data for determining the morphological activities of the ice during different types of water discharge in connection with river-water control for hydraulic-power stations and the changes of the water energy under the ice surface in different river systems.