First. The depth of water between the city and Goat Island is excessive, thus making the pier foundations very expensive.

Second. A large proportion of the steamers using the harbor would have to pass under the structure.

Third. The War-Department requirements in respect to both horizontal and vertical clearances would be excessive for this location, because of the large number of vessels passing; and, in consequence, the cost of structure would be greatly augmented.

F. By locating further inside the Bay, the depth of water would be reduced to a reasonable amount, and the number of vessels passing the structure would be comparatively small. In fact, the farther back from the harbor-entrance the structure is located, the smaller will be the depth of water and the fewer will be the passing vessels. On the other hand, though, the greater will be the total length of structure, the farther from the center of population will be its city end, and the greater will be the distance which the passengers will have to travel.

G. Practically nothing is known about the characters of foundations that would be encountered at the various proposed locations; and no provision has been made for money to make the necessary borings.

H. It is impracticable to obtain a final decision concerning required span-lengths until a bona fide design, properly backed, has been presented to the War Department for approval.

I. In regard to minimum clear-headway, it is probable that the farther inside the harbor the location the less the requirement, because the smaller and less important would be the passing craft, and the fewer the number thereof. Some of them might be forced to lower topgallant masts in order to pass beneath the structure.

J. There would be a serious objection to any opening span, because of the delay which would be involved by its operation. The real raison d'être of the structure is rapid transit, hence to interfere with that in any way would be highly objectionable.

K. The total cost of structure would decrease to a certain point as the location is moved up the harbor, because of cheaper foundations and the consequently shorter spans; but beyond the said point it would increase because of the greater length of bridge.

L. The more expensive the structure the longer will be the time required to build it; hence it may be concluded that one of the inner-harbor locations would need much less time for completion of bridge than the Goat-Island layout. This matter of time for completion of structure possesses a double importance, because any delay increases the item of cost due to interest during construction; and by postponing the inception of operation it involves a loss of income from use.

From the preceding it is evident that the solution of the initial economic problem in connection with the proposed San Francisco Harbor bridge is one of considerable complication.