Abstracts of Technical Articles by Bell System Authors (01 January 1948)

Jour. Amer. Chemical Soc., May 1947. Indus. & Engg. Chern., September 1947. Telephony, August 30, 1947. 175 176 BELL SYSTEM TECHNICAL JOURNAL nique is called Pulse Code Modulation or simply P C M . An eight-channel system embodying these principles was developed and produced in portable form for field operation. Other work carried on simultaneously by W. M. Goodall (see B. S. T. J., July 1947) resulted in the development of an experimental system using a different method of coding. In carrying out this new type of modulation, the speech wave applied to each channel is, in effect, transmitted sample by sample, and each sample is represented by a multi-unit code employing on-or-off pulses, hence the term PCM. 

This method appears to have exceptional possibilities from the standpoint of freedom from interference. Its full significance in connection with future radio and wire transmission may take some time to reveal. Stereoscopic Drawings of Crystal Structures.4 W . L . BOND. A method is presented for getting stereoscopic pairs of atomic structure views given the coordinates of the atoms and cell constants. Properties of Liquids at High Sound Pressure.5 H . B . BRIGGS, J . B . JOHNSON and W. P. MASON. When sound of high amplitude is transmitted into a liquid by means of a mechanical driving device, the ultimate limitation to the power that can be transferred is cavitation or breakdown of the liquid under high internal stresses. A study of cavitation has resulted in establishing the following results.