It is impossible, within the limits of a single chapter, to discuss each kind of company separately. The investment value of street-railway bonds will be here considered, and it is felt that the general principles advanced, with slight modifications of detail, will be found equally applicable to a judgment of other forms of public-service securities. I. _Safety of Principal and Interest._ In order to determine the safety of a street-railway company's bonds, the company must be subjected to a threefold examination, physical, financial, and political. An examination must be made into the extent and condition of the physical property in order to ascertain whether the bonded debt is secured by property having a real market value in excess of the face amount of bonds issued. The first point to be determined is the extent and valuation of the company's real estate. If the appraised value of the land upon which power-houses and car-barns have been erected is alone greater than the amount of bonds outstanding, the investigation need go no further, for the bonds, in such a case, would be practically a real-estate mortgage. In most instances, however, this is very far from being the case; and after careful appraisal of the real estate it is then necessary to make a careful valuation of the other physical property; namely, power-plants, depots, car-sheds, roadway, and equipment. It is usually impossible for the average investor to make such an examination himself, nor is it likely that he would possess sufficient technical knowledge to render his investigation of much value. For an accurate estimate of the value of a street-railway's physical property, it is usually necessary to depend upon the expert opinion of a trained engineer. It is a matter of regret that the average street-railway report can not be relied upon to furnish an accurate valuation of the physical property; and it is accordingly customary for careful bond-dealers, when they contemplate taking an issue of street-railway bonds for distribution among their clients, to have the property examined by a competent engineer, whose report then determines for them the question of taking the issue. Disregarding the figures which show the cost of property and equipment upon the company's books, the engineer proceeds to make a careful estimate of the replacement value of the property, including real estate. If the result of the examination shows that the property could not be duplicated for the amount of the bond issue, the company occupies an unusually strong position--altho even in such a case some part of the value of the bonds comes from the strength of the company as a going concern. In most cases, however, it is probably found that the bond issue is in excess of the value of real estate and the replacement value of the physical property, the balance representing a capitalization of the franchise.