HARTREE, D. R., and J. R. WOMERSLEY, A Method for the Numerical or Mechanical Solution of Certain Types of Partial Differential Equations, _Proceedings of the Royal Society of London_, series A, vol. 161, 1937, pp. 353-366. MAGINNISS, F. J., Differential Analyzer Applications, _General Electric Review_, vol. 48, no. 5, May 1945, pp. 54-59. SHANNON, CLAUDE E., Mathematical Theory of the Differential Analyzer, _Journal of Mathematics and Physics_, Cambridge, Mass.: Massachusetts Institute of Technology, vol. 20, no. 4, 1941, pp. 337-354. HARMONIC ANALYZERS AND SYNTHESIZERS Another branch of the analogue calculating machine is the harmonic analyzer and synthesizer. These are machines that study wave motions and related physical and mathematical functions. A brief list of articles on this type of machine follows: ARCHER, R. M., Projecting Apparatus for Compounding Harmonic Vibrations, _Journal of Scientific Instruments_, vol. 14, 1937, pp. 408-410. BROWN, S. L., A Mechanical Harmonic Synthesizer-Analyzer, _Journal of the Franklin Institute_, vol. 228, 1939, pp. 675-694. BROWN, S. L., and L. L. WHEELER, A Mechanical Method for Graphical Solution of Polynomials, _Journal of the Franklin Institute_, vol. 231, 1941, pp. 223-243. BROWN, S. L., and L. L. WHEELER, Use of the Mechanical Multiharmonograph for Graphing Types of Functions and for Solution of Pairs of Non-Linear Simultaneous Equations, _Review of Scientific Instruments_, vol. 13, Nov. 1942, pp. 493-495. BROWN, S. L., and L. L. WHEELER, The Use of a Mechanical Synthesizer to Solve Trigonometric and Certain Types of Transcendental Equations, and for the Double Summations Involved in Patterson Contours, _Journal of Applied Physics_, vol. 14, Jan. 1943, pp. 30-36. FÜRTH, R., and R. W. PRINGLE, A New Photo-Electric Method for Fourier Synthesis and Analysis, _London, Edinburgh and Dublin Philosophical Magazine and Journal of Science_, vol. 35, series 7, 1944, pp. 643-656. INTERNATIONAL HYDROGRAPHIC BUREAU, _Tide Predicting Machines_, International Hydrographic Bureau, Special Publication 13, July 1926. KRANZ, FREDERICK W., A Mechanical Synthesizer and Analyzer, _Journal of the Franklin Institute_, vol. 204, 1927, pp. 245-262. MARBLE, F. G., An Automatic Vibration Analyzer, _Bell Laboratories Record_, vol. 22, Apr. 1944, pp. 376-380. MAXWELL, L. R., An Electrical Method for Compounding Sine Functions, _Review of Scientific Instruments_, vol. 11, Feb. 1940, pp. 47-54. MILLER, DAYTON C., A 32-Element Harmonic Synthesizer, _Journal of the Franklin Institute_, vol. 181, 1916, pp. 51-81.