maintenance, and operation; and how the necessary funds are to be provided.

The actual conditions for the proposed San Francisco Harbor bridge, as well as they can be stated at present, are as follows:

A. There is a large possible income from passenger traffic, mainly from commutors who now use the ferry, most of which traffic would soon be diverted to the structure, provided that truly-rapid transit thereon be furnished at all times; and the said income, under present conditions, would be large enough to warrant the building of an open-decked, double-track, electric-railway bridge that would carry no other kind of traffic.

B. There is a rapidly increasing amount of automobile traffic now cared for by the ferry; and this, undoubtedly, would be augmented materially by the superior and, possibly, cheaper service of the bridge; nevertheless it is doubtful whether it would be large enough to warrant the building of separate passageways with paved floor and the necessarily-greater carrying capacity of the trusses.* It would be out of the question to let the automobiles use the same space as the electric trains; for such an arrangement would prevent the rapid transit of the latter.

C. There is an immense amount of freight crossing the water; but, for two reasons, it does not appear probable that it would ever be economical to transport it over a bridge. The first reason is the great height to which both it and its containing vehicles would have to be lifted, and the consequent expense of such lifting. The second is the greatly augmented cost of structure, due to the far larger live loads for both the floor system and the trusses, which the carrying of such freight would necessitate. It would probably be more economical either to transfer the freight by ferry, as is done at present, or to carry it by rail around the south end of the Bay.

D. There is at certain seasons a large amount of passenger traffic to and from San Francisco by certain trans-continental railroads; hence the question arises whether the passengers should be carried across in the steam-railway cars on which they travel or whether they should go over in the electric-railway cars. The objection to the latter method is the individual trouble, inconvenience, and loss of time for each passenger; while the objection to the former is the increased cost of structure due to the difference in the live loads between steam-railway cars and electric-railway cars. Of course, the former cars would have to be hauled in short trains by electric motors, so as to avoid the excessive concentrated loading from the heavy steam-locomotives.

E. The most direct route for the crossing is from Telegraph Hill to the outer end of Goat Island, and thence to near the Oakland Pier; and this is the one to which, until quite lately, most attention has been paid. The main objections to it are as follows:

* Since this was written, the immense development of automobile travel and motor-truck traffic throughout the entire country might reverse this economic conclusion.