In the previous paper, effect of external disturbance on ageing of permanent magnet was discussed. In this paper, other factors related to the amount of ageing have been discussed one by one, the result of which can be summarized as follows:
1) Advance of natural ageing will increase to some extent the stability of permanent magnet against external disturbance.
2) Decrease in dimension ratio generally causes larger amount of ageing, but it is not always so in the case of temperature co-efficient of flux.
3) All of the various kinds of demagnetization to bring about stabilization, have effect of decreasing the amount of ageing, but they are not equally effective.
4) Natural ageing after demagnetization to bring about stabilization is found to be characteristic; after a certain amount of demagnetization, increase of magnetism has been observed.
5) Degree of magnetization is found to have influence on the ageing behavior due to external disturbance that occurs thereafter.
6) Re-magnetization has effect to cancel the previous deterioration due to external disturbance.
7) Continuous and intermittent heating has almost the same effect on the decreasing behavior of magnetism caused by the heating.

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There are two types of analog computer, repeated type and slow speed type. The former is convenient to catch the optimum condition observing the response, but precise record can not be obtained.
This paper describes the performances of a repeated type analog computer made by Tokyo Shibaura Electric Co., Ltd. The experiments show that the computer is also valuable as slow speed type when the recording duration is limited to about 10 seconds. According to the circle test on the second order differential equation, the computer shows about 2% accuracy as repeated type computer, while about 1% accuracy as slow speed type.

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Features of a new code of the commutator type Analog-to-Digital converter and its decoding circuits are discussed. This converter can digitize a shaft position into a four elements reflected decimal code. In the reflected decimal code, it is required to convert the code when the preceding decade is odd. The importance of the converter using four elements decimal code lies in its function to simplify the decoding circuits. The new code has been designed to make it easy to distinguish even number from odd one, so that the decoding circuit can be simplified as shown in Fig. 2. Each sampled code is converted into read-out code through the simple logical circuit of Figures 1 and 4. This paper also describes a simple method to convert the read-out code into analog quantity of voltage as indicated in Fig. 6, taking an example of digital servomechanism. The sequence of operations of the decoding circuit is discussed in the appendix, taking account of delay time of relays.

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プロセス工業の計測および制御設備を図示するに用いるシンボルとして,わが国では工業毎工場毎にかなりまちまちなものが使用されていて,統一制定が特に要望されている。当学会では昨年4月多くの業界および関係学会から委員の参加を願い,シンボル委員会を組織して,シンボルJIS原案の作成をねっていた。最近その原案がまとまったのでここに掲載して広く学会会員並びに一般の意見を問うことになった。この原案は今後日本工業標準調査会によって審議される運びになるが,もし内容について御意見があれば昭和32年6月30日までに当学会編集部宛に提出されたい。(東京都文京区本富士町1,東京大学工学部応用物理学教室,日本計測学会編集部)
案を作成するに当って,おおよそISA工業計測用シンボル(仮規格)*に準拠することとし,必要な変更をほどこす方針をとった。たとえば油圧配管の図記号をいれたこと,プロセス変量の文字記号として熱量Qをつくったこと,導電度Cを除いたこと,その他のプロセス変量を表わすXを採用したこと,また積算を表わすSを採用したこと,ガラスGを除いたことなどが主な点である。JIS本規格にはこれらの内容が解説の中にくわしく説明されるはずである。

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