MILLER, DAYTON C., The Henrici Harmonic Analyzer and Devices for Extending and Facilitating Its Use, _Journal of the Franklin Institute_, vol. 182, 1916, pp. 285-322. MILNE, J. R., A “Duplex” Form of Harmonic Synthetiser and Its Mathematical Theory, _Proceedings of the Royal Society of Edinburgh_, vol. 39, 1918-19, pp. 234-242. MONTGOMERY, H. C., An Optical Harmonic Analyzer, _Bell System Technical Journal_, vol. 17, no. 3, July 1938, pp. 406-415. RAYMOND, W. J., An Harmonic Synthesizer Having Components of Incommensurable Period and Any Desired Decrement, _Physical Review_, vol. 11, series 2, 1918, pp. 479-481. ROBERTSON, J. M., A Simple Harmonic Continuous Calculating Machine, _London, Edinburgh and Dublin Philosophical Magazine and Journal of Science_, vol. 13, 1932, pp. 413-419. SOMERVILLE, J. M., Harmonic Synthesizer for Demonstrating and Studying Complex Wave Forms, _Journal of Scientific Instruments_, vol. 21, Oct. 1944, pp. 174-177. STRAITON, A. W., and G. K. TERHUNE, Harmonic Analysis by Photographic Method, _Journal of Applied Physics_, vol. 14, 1943, pp. 535-536. WEGEL, R. L., and C. R. MOORE, An Electrical Frequency Analyzer, _Bell System Technical Journal_, vol. 3, 1924, pp. 299-323. NETWORK ANALYZERS A third branch of the analogue calculating machine is the network analyzer. To solve problems, this machine uses the laws governing a network of electrical circuits. For example, an electric power company with a system of power lines over hundreds of miles may have a problem about electrical power: will an accident or a sudden demand cause a breakdown anywhere in the system? In the General Electric Company in Schenectady, N. Y., there is a machine called the A.C. Network Analyzer. All the properties of the power company’s network of lines can be fed on a small scale into the analyzer. Certain dials are turned and certain plugwires are connected. Then various kinds of “accidents” and “sudden demands” are fed into the machine, and the response of the system is noted. The answers given by the machine are multiplied by the proper scale factor, and in this way the problem of the power company is solved. There are two kinds of problems that network analyzers are built to solve: the steady state conditions and the transient conditions. For example, you may not overload a fuse with an electric iron when it is plugged in and being used, but as you pull out the cord, you may blow the fuse: the steady state does not overstrain the system, but the transient does. Some articles on network analyzers are: ENNS, W. E., A New Simple Calculator of Load Flow in A.C. Networks, _Transactions of the American Institute of Electrical Engineers_, vol. 62, 1943, pp. 786-790.