Abstract: Measurement of the skin friction of piles, according to which a skin-friction measuring device having a cylindrical testing part which is rotatable relative to a main body of the device is introduced into a bored hole in a ground and is rotated by a boring rod, and by rotating the boring rod, the friction force then generated between the cylindrical testing part and the wall of the bored hole is determined in terms of the torque required for rotating the cylindrical testing part.

Abstract: In a telephone system having an automatic response function wherein a predetermined answer message is automatically sent to a calling originator when a speaking path to the calling originator is established in response to a call signal originated by calling from the calling originator, there are provided a DTMF signal decoder for decoding a DTMF signal sent from the calling originator as a result of key operation at the calling originator after the speaking path has been established, and a memory for storing operated key data corresponding to the output of the DTMF signal decoder, whereby information regarding the calling originator is obtained when the stored content of the memory is zero.