In 192~, the startup of hydraulic units at the first fruits of Soviet hydraulic engineering --the Volkhov and Boz-Sui hydroelectric plants --signaled the start of operation of Soviet hydroelectric plants, the accumulation of their operating experience, the gradual improvement of all methods and means of operational maintenance and the use of hydroelectric plants as special sources of electric supply, and the complex utilization of water sources in the rivers and reservoirs of the USSR. A new important llnk had manifested itself in the improvement of the technologlcal properties of hydraulic plants on the basis of the utilization of the operating experience in the design and construction of hydro projects, and in the development of new equipment. Each of the following phases of development of Soviet water power have reflected all of the most valuable operation of constructed plants that has been concentrated into experience and the dissemination of leading experience accumulated by the plants.In this respect, the services rendered by the Journal C,4drotekhn~heskoe Si'ro~tel'stooj which has focused attention on problems involving the operation of hydroelectric plants and on the dissemination of accumulated and leading experience since the start of publication, have been outstanding.From the standpoint of operating conditions, it is possible to designate five basic stages in the development of domestic water power.The inltial prewar stage (1926)(1927)(1928)(1929)(1930)(1931)(1932)(1933)(1934)(1935)(1936)(1937)(1938)(1939)(1940) was characterized by disassociation of hydroelectric plants, and weak organizational, technical, and electrical ties. Nevertheless, it was precisely in this period that the fundamental principles of the technical operations of hydroelectric plants, many of which have remained in effect even during the modern period, were established. In these years, a group of derivation hydroelectric plants were placed in service: the Zemo-Archalsk, Rioni, Kanaker, and Dzoragetsk plants in Trans-Caucasia, the Baksan and Gizeldon plants in Northern Caucasla, the Kondopogo plant in Kareli, the Lower Tuloma and Niva-2 plants on the Kola Peninsula, the Kadyrin and Chirchik plants in Uzbeklstan, the Ulba plant in Altae, etc. At these plants, methods for the reliable service of derivation courses were worked out, and hydraulic turbines of various types, including bucket turbines, were sought by overcoming various difficulties associated with the characteristic features of the hydrologlcal reglme of the alpine rivers.In this same period, hydroelectric plants, which were constructed in accordance with schemes involvin E dams and which were considered large for that time, were placed in service: the Volkhov, Lower Svir, Uglich, and other plants.The Dnepr--Lenin plant, which was unequaled in Europe, stood apart from the rest on the basis of its gradioseness and nationaleconomic significance.The overall capacity of active hydroelectric plants exceeded 1.5 million kW at the outset of 1941.As early as 1931, the journal w...