not needed for navigation, the best type of approach to adopt is a succession of deck spans of, as nearly as may be, economic length.

In the design for the anchorages there is a fine opportunity for benefiting from economic study. There are three general cases of governing conditions to consider, viz., foundations on bed rock, foundations on piles, and foundations on clay or similar material without piling. If the bed rock is fairly close to the surface, it will be advisable to found upon it; but otherwise it will be cheaper to put in shallow foundations, obtaining the necessary supporting power either by piling or by spreading the base. The maximum of economy will be obtained by making both the weight of masonry in the rear of the anchorage and the foundation area in the front thereof proportionately as large as practicable. The first expedient tends to increase the resisting moment against overturning, and the second to reduce the intensity of bearing at the toe of the face, where, of course, it is greatest. It is economic, therefore, to make the anchorages long and narrow, low in the front and high in the rear. If there be several of these in the form of walls one for each cable, or pair of cables,—instead of one solid mass of concrete, they can be advantageously connected in front below the ground so as to spread the base, and joined in the rear by a great wall above the ground, in order to increase the weight there.

If piles be employed, they should be driven as closely together as practicable near the front of the anchorage, and, if it be found advisable, spread somewhat near the rear thereof-in other words their spacing should be adjusted to the intensity of the foundation loading. That intensity should be made as nearly uniform as possible over the entire base by the expedient just explained, thus avoiding the call for varied spacing.

With a single exception, the preceding considerations cover all the important economic features in the designing of suspension bridges. That exception is the question of the comparative economics of wire cables and high-alloy-steel eye-bar-cables, concerning which hitherto absolutely nothing definite has been known. It is one of the series of ten major economic problems in bridgework that in 1916 the author undertook to solve. Its investigation was completed in March, 1920; and the results thereof, as herein previously stated, were presented two months later, in the form of a memoir to the Engineers' Society of Western Pennsylvania. In view of the fact that the said memoir is very complete, it is here reproduced verbatim as follows:

Comparative Economics of Wire-Cables and High-Alloy-Steel
Eye-Bar-Cables For Long-Span Suspension Bridges

The economic comparison of wire cables and eye-bar cables for suspension bridges has never before been brought to the attention of American engineers, for the reason that comparatively few structures of the suspension type have been built in this country. Their unsuitability for