Second. That the basis for computing a fair rate is the fair value of the property, which must be arrived at by a computation or series of computations taking into account many different factors. Third. That while the Court mentions certain things that may serve as indices of value, which are to be taken into account and given due weight, the Court does not outline or define any method of arriving at a value, but does recognize it as an embarrassing question. Fourth. That no such stress has been laid by the Court on original cost as has been construed by some appraisers. The principles enunciated in Smyth _vs._ Ames are reiterated by the Court in San Diego Land Company _vs._ National City (174 U. S., 739), with the further ruling: "The contention of the appellant in the present case is that, in ascertaining what are just rates, the Court should take into consideration the cost of its plant; the cost per annum of operating the plant, including interest paid on money borrowed and reasonably necessary to be used in constructing the same; the annual depreciation of the plant from natural causes resulting from its use; and a fair profit to the Company over and above such charges for its services in supplying the water to consumers, either by way of interest on the money it has expended for the public use, or upon some other fair and equitable basis. Undoubtedly, all these matters ought to be taken into consideration and such weight given them, when rates are being fixed, as under all the circumstances will be just to the company and to the public. The basis of calculation suggested by the appellant is, however, defective in not requiring the real value of the property and the fair value in themselves of the services rendered to be taken into consideration. What the company is entitled to demand, in order that it may have just compensation, is a fair return upon the reasonable value of the property at the time it is being used for the public. The property may have cost more than it ought to have cost, and its outstanding bonds for money borrowed, and which went into the plant, may be in excess of the real value of the property. So that it cannot be said that the amount of such bonds should in every case control the question of rates, although it may be an element in the inquiry as to what is, all the circumstances considered, just to both the company and the public." In the case of Columbus Southern Railway _vs._ Wright (151 U. S., 479), the Court quotes approvingly from Franklin Company _vs._ Railroad (12 Lea (Tenn.), 521-537-538-539), and shows that the doctrine quoted had already been enunciated by the Supreme Court in the State Railroad Tax Cases (92 U. S., 575-607). The Court quotes as follows: