Annual carrying charges

IT IS ADMITTEDLY difficult to anticipate future variations in some of the factors involved in economic studies, such as taxes and probable life, just as it is difficult for the transmission-line designer to anticipate future loads and power factors. But in neither problem is the correct arithmetic a matter of personal judgement; the arithmetic of economic comparisons is as rigorous and clear-cut as Ohm's Law. This article deals with the appropriate treatment of return on the investment, depreciation, taxes, and insurance.