This division is convenient but arbitrary. It is the division of an engineer rather than of an economist; for these so-called non-physical values are like the breath of a man's life; without them, the physical value is like the discarded body. Again, the use of negative non-physical values, while convenient, may not be wholly logical. These remarks are not directed at Mr. Riggs, for he is careful to say that he is dealing only with active enterprises, and not with those which are inert, and the speaker realizes that he is not attempting primarily to build up a logical argument, but to formulate certain rules to overcome practical difficulties met by all who have attempted valuation work. As many who have not given this matter much thought are apt to be misled by the distinction made between physical and non-physical values, they should bear in mind that the line between them is like the equator, an imaginary one. _Water._—"The water is as much a part of the cost of putting that line there as the rails," remarked a corporation official, of admirable character and wide experience, pointing to a trolley line from the window of a Pullman car; and, bearing in mind what he meant by "water," this is undoubtedly so. The cost of promoting the enterprise, the discount on the hazard, the loss of interest during its infancy, the labor of building up the undertaking—these are all real elements of cost, and may remain in the property as value, but, like all other items of cost, they have their reasonable limits, which, in each individual case, can be determined within narrow bounds.