This paper proposes a constant temperature bath suitable for improving the performance of the zener diode type reference voltage previously presented. The bath consists of a double-layered Cu-box, which reveals the following distinctive features: (i) The temperature resolution belowes to the level of 10^-5°C; (ii) the fluctuation width is smaller than 5×10-⁵°C (p-p) and (iii) the steady state error remains within 8.6× 10-⁵°C even if the temperature in the outer box varies by 5.9°C. This bath affirms the reference voltage of sevenfigures resolution.

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乾燥密度1.2，1.4，1.6 Mg/m3に締固めて作成したベントナイト供試体を飽和させた後に，摂氏60度，90度，120度のに1年程度いれて，膨潤圧と透水係数を測定した．その結果，中の供試体の膨潤圧は時間とともに低下し，その程度は温度が高いほど大きいこと，高温槽から取り出し，室温下で測定した膨潤圧と透水係数は，に入れる前に測定した値と大きな差はないことなどがわかった．

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Synchronous commutator system shows a sort of frequency selective character, which can be sharpened to any desired extent by increasing the time constant of indicator. If the time constant of the indicator is not large enough, the additional time constant circuit may be applied. However, the increased time constant requires longer measuring time, which is accompanied with various disadvantages. The author calculated the frequency selective characters obtained by multi-stage CR time constant networks whose time constant had been adjusted so as to have the transient time equal to that of the single stage which is usually used. The results show that the independed multistage CR circuits appeared in Figs. 9 and 10 have improved their characters. This fact was also confirmed by the simple experiment about the circuit (c) which is shown in Figs. 11, 12 and 13.

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A precision thermostatic air chamber is described in which the air and the inner walls are kept at the same temperature.
The air chamber has a double-walled structure and a heat exchanger of which the temperature effectiveness is close to 100%. The air and water passed through the heat exchanger are respectively forced to flow into the air chamber and into the interspace of the double walls. The trial air chamber described here is of cubic form each side of which is 30cm, and the thickness of the double walls is 30mm.
The distribution of air temperature in the chamber is measured by 27 resistance thermo-meters arranged in a space lattice. Results of measurement with a thermostatic air chamber tester show that the temperature difference between the air and the inner walls is almost zero.
Data are presented on the temperature control and the dynamic characteristics of the air chamber are discussed.

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