There has been a great impetus given during the last few years to the application of mathematical analysis for the solution of technical problems. This interest in the use of mathematics by the technologist is a result. of the remarkable developments that have appeared in the various branches of engineering and physics as a result of close collaboration of theory and experiment in the research laboratories of industrial plants and elsewhere. A half a century ago, engineers regarded the differential and integral'calculus as a mystery beyond the reach of the majority. However, at present, the engineering student takes the calculus in his stride. The use of complex quantities in the solution of electrical and mechanical problems has brought the engineer to at least a superficial study of the rudiments of the complex variable. Other studies of the behavior of systems of technical importance have ushered in matrix algebra,. operational methods, the study of orthogonal functions, partial differential equations, and other mathematical techniques into the required mathematical equipment of a person who uses mathematics to solve-technical problems of various kinds, such as acoustical, electric矶，aeronautical, mechanical, thermal, etc.