Theoretical and experimental considerations are thoroughly made on one-quadrant electronic analog, dividers. There are two types known in the divider circuit working on the principle of reciprocal multi-plication. One (A) employs a multiplier and a high gain amplifier, and the other (B) a multiplier, an adder and a sign changer (Fig. 1). Study is made on the both types. Conclusion of this paper is summarized as follows:
(1) Equivalent circuit of the above two is, as a principle, the same one (Fig. 2).
(2) Static error of a divider due to defficient amplification of the equivalent amplifier can be effectively compensated by inserting a constant compensating voltage to the divisor X₂ terminal (Firs. 3 & 4).
(3) Graphical analysis-method has been developed to clarify the relations between divider's static errors and multiplier's ones. The method can be applied to any given divider. As a result of the analysis, it is generally said that the smaller the divisor X₂ is, the worse the multiplier's error affects the divider's (Fir. 5).
(4) A multiplier incorporated into a divider must be the one that has the least static error at smaller X₂ input. A divisor X₂ has to be applied to a more accurate terminal of a multiplier at smaller input.
(5) Operating level of a multiplier when incorporated into a divider can not, in principle, go over its output rating X_Mr. divided by R (R=X_2max/X_2min, X₂=divisor, Fig. 6).
(6) Operating level of a multiplier incorporated into a divider can be raised over the above value, only if divisor X₂ always >X₂ min when dividend X₁=X_1max or if X₁ always <X_1max when X₂=X_2min.
(7) A straightforward design method is given as to how to allocate appropriate gain constants to each element of a divider system (Figs. 7 & 8).
(8) No abnormal instability occures in (A)-type divider and (B)-type one with δ₀<0 (Fig. 10). (1+δ₀ means d. c. gain of the system composed of an adder and a sign changer).
(9) Only in (B)-type divider with δ₀<0, abnormal instability may take place. This instability can be explained by non-linearity which may exist between multiplier's output and input at its small output and by saturation characteristics of the system composed of an adder and a sign changer (Fig. 11). The instability, however, can easily be checked by a diode shunting the output-X_D terminal to chassis earth (Fig.12).
(10) Dynamic response characteristics of a divider is mainly determined by the character of divisor X₂ and the lower the level of X₂ is, the worse it becomes.
(11) Qualitative character of transient response of X_D (divider output) is determined only by X₂₂ and neither by X₂₁ nor X₁₀ when dividend input X₁ (t) =X₁₀ const. and divisor input X₂ (t) varies in step from X₂₁ to X₂₂. This is proved theoretically and experimentally as well (Fig. 13 & Photo. 1).
(12) Amplitude of transient response in X_D in the above case is proportional to (X_D2-X_D1). (X_D1 being stationary output of a divider when X₁ (t) =X₁₀ and X₂ (t) =X₂₁ and X_D2 being alike when X₂ (t) =X₂₂).

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To obtain long continuous data of temperature characteristics of a standard self-inductor, anautomatic balance bridge with a recorder (Fig. 6) was constructed. Two components are drawn from the unbalance voltage of a transformer bridge, one corresponding to the unbalance of inductance and the resistance. The former controls a motor connected to a small variable inductor while the latt er another motor connected to a variable resister of potentio type. Obtained results (Fig.8) were satisfactory for inductor 1 mH-1 H. Many standard self-inductors were measured and temperature-coefficients (Table 3) of 10°C-30°C were obtained.

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Several kinds of pyrometers which utilize the theory of thermal radiation are used for measuring high temperatures, however they have such a defect that they do not indicate true temperatures. The two color pyrometer has a useful characteristic of indicating comparatively true temperatures in the wide range of temperature. Described in this paper are the principle and structure of this automatic two color pyrometer, particularly the selection of color filters and new measuring circuit.

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Magnetic flowmeters small in tube-diameter are known to be easily calibrated using appropriate tanks and clocks, however, for large diameter ones, there arise many difficulties. On the other hand, it is also known that there exists a theoretical relationship between flowrate and output voltage, which, in an ideal case, is represented by the following equation: E=B·D·u_zwhere B: flux density, E: output voltage, D: diameter, u_z: mean flow velocity in MKS unit In actual cases, however, another coefficient should be factored on the right hand side. This paper discusses the coefficient either theoretically or based on the experiments made by the author.
1) The original relationship is transformed into such a form as E/I=B/I·D·u_z where I: exciting current. The left hand side is an easily measurable quantity especially when the exciting source for the flowmeter regarded as an active impedance is ordinary commercial one.
2) Flux density B varys as the source voltage and frequency fluctuate, but the quantity B/I does not. This quantity is measured, compared with that of a standard solenoid with known dimensions.
3) Theoretical value of coefficient is derived in terms of distributions of the flux density and flow velocity for actual cases in which both of the distributions are not necessarily be uniform. Theoretical results show a very good coincidence with experimental data.
4) To avoid undesirable effects of rapid fluctuation of flow during measuring period, output voltage is transduced into pulse rate and integrated by a pulse counter. The result is calibrated by a tank of 100m³ volume for a magnetic flowmeter of 3m³/sec. of full scale with an accuracy of 0.5%.
5) This paper also describes the calibration data using current-meters and/or Pitot's tubes for a magnetic flowmeter actually installed in a penstock of Kamo Hydropower Plant.

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Process which is serially connected with interacting linear lags in many stages is frequently seen in actual process control system. This paper presents the relations between dead time and dead zone to stabilize the system which consists of three position relay element, dead time and serially connected two stage process with interacting linear lags. Frequency response of the system is also investigated. Validity of the above analysis is proved through experiments on the practical system which employs a sinusoidal signal generator of pneumatic pressure by relay servo.

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