Fig. 2 shows osciHograms obtained by this method. Tests were carried out with galvanometer type FtlT/3 (W M = 1.1 d. cm/rad) whose moving part was immersed in oscillographic liquid type I. The viscosity of this liquid varies at 20"C between 10-18 centistokes, and its specific gravity amounts to 0.95 g/era s. A high-speed silicone photocell operating as a photodiode was used in the circuit. A periodic excitation of a transient condition in the photocompensator was produced by a low-frequency square-wave generator. In order to check the accuracy of this method tests were made at two different values of the amplification factor. Oscillograma (Fig. 2) was taken with a gain of 90,000 and oscillogrambat 170,000. We find from the first surge in Fig. 2a [3] that ~ = 0.2, and from the time marks that T = 0.008 sec. From (3) and (4) we find that J=0.16 g. cm z, P=50.5 d'cm. see/tad. In the same way we find from Fig. 2b that 8 = 0.125, T = 0.0053 sec and J = 0.14 g. cm ~, p= 40 d. cm" sec/rad. The dispersion of parameters obtained with different gains did not exceed 10% of their mean value. Such an accuracy is amply sufficient for the solution of any practical problem. The above method can be applied for determining the dynamic coefficients not only of galvanometers, but also of any other highly damped systems providing they can be connected to an amplifying circuit with a large gain and anover-all negative feedback. LITERATURE CITED