This book is founded on the lectures in Engineering Economics, delivered yearly to the Graduate Class in Engineering of the Benares Hindu University. Its title is justified by the fact that it is chiefly concerned with the Economics of Mechanical and Electrical Engineering, but it includes a great deal that does not fairly come under that bending. There is, for example, a chapter on Law, which, it is hoped, may be of material assistance to those who contemplate launching a new enterprise, especially in the initial phase. It is an attempt to make the instruction given to Engineering students more practical in the business sense than has hitherto been customary in Engineering colleges.