The authors have reported in 1951, on a system of indicating shaft-horsepower with a wattmeter to which an electric type torsionmeter and an electric tachometer are connected. Since then, further researches have been made with the intention of consummating the shaft-horsepower meter, especially we made our efforts to the simplification of its control, the maintenance of its accuracy, and the diminution of its cost. In this paper, the progress of researches made on improving the shaft-horsepower meter is reported.