HAZEN, H. L., and others, _The M.I.T. Network Analyzer_, Cambridge, Mass.: Massachusetts Institute of Technology, Department of Electrical Engineering, Serial No. 69, Apr. 1931. KUEHNI, H. P., and R. G. LORRAINE, A New A.C. Network Analyzer, _Transactions of the American Institute of Electrical Engineers_, vol. 57, 1938, pp. 67-73. PARKER, W. W., Dual A.C. Network Calculator, _Electrical Engineering_, May 1945, pp. 182-183. PARKER, W. W., The Modern A.C. Network Calculator, _Transactions of the American Institute of Electrical Engineers_, vol. 60, Nov. 1941, pp. 977-982. PETERSON, H. A., An Electric Circuit Transient Analyzer, _General Electric Review_, Sept. 1939, pp. 394-400. VARNEY, R. N., An All-Electric Integrator for Solving Differential Equations, _Review of Scientific Instruments_, vol. 13, Jan. 1942, pp. 10-16. Some of the articles on applications of network analyzers to various problems are: KRON, GABRIEL, Equivalent Circuits of the Elastic Field, _Journal of Applied Mechanics_, vol. A11, Sept. 1944, pp. 146-161. KRON, GABRIEL, Tensorial Analysis and Equivalent Circuits of Elastic Structures, _Journal of the Franklin Institute_, vol. 238, Dec. 1944, pp. 399-442. KRON, GABRIEL, Numerical Solution of Ordinary and Partial Differential Equations by Means of Equivalent Circuits, _Journal of Applied Physics_, vol. 16, 1945, pp. 172-186. KRON, GABRIEL, Electric Circuit Models for the Vibration Spectrum of Polyatomic Molecules, _Journal of Chemical Physics_, vol. 14, no. 1, Jan. 1946, pp. 19-31. KRON, G., and G. K. CARTER, A.C. Network Analyzer Study of the Schrödinger Equation, _Physical Review_, vol. 67, 1945, pp. 44-49. KRON, G., and G. K. CARTER, Network Analyzer Tests of Equivalent Circuits of Vibrating Polyatomic Molecules, _Journal of Chemical Physics_, vol. 14, no. 1, Jan. 1946, pp. 32-34. PETERSON, H. A., and C. CONCORDIA, Analyzers for Use in Engineering and Scientific Problems, _General Electric Review_, vol. 48, no. 9, Sept. 1945, pp. 29-37. MACHINES FOR SOLVING ALGEBRAIC EQUATIONS Another branch of the analogue calculating machine is a type of machine that will solve various kinds of algebraic equations (see Supplement 2). A list of some articles follows. The article by Mallock describes a machine for solving up to 10 linear simultaneous equations in 10 unknowns, and the article by Wilbur, a machine for solving up to 9. DIETZOLD, ROBERT L., The Isograph—A Mechanical Root-Finder, _Bell Laboratories Record_, vol. 16, no. 4, Dec. 1937, pp. 130-134.