has lately designed the piers for three important Southern bridges in the latter manner. They were put down without much difficulty, the principal hindrance being from sunken logs, and were eminently economical in first cost as compared with piers of other possible designs.

Piers may be divided into the following classes in respect to the materials of which they are built:

1. Stone-masonry piers resting on—

A. Bed-rock.

B. Timber and concrete caissons.

C. Steel and concrete caissons.

D. Timber grillages supported on piles.

2. Brick-masonry piers resting on the same foundations as mentioned for stone-masonry piers.

3. Unprotected concrete piers resting on the same foundations as mentioned for stone-masonry piers.

4. Oblong steel shells filled with concrete and resting on the same foundations as mentioned for stone-masonry piers.

5. Cylinders filled with concrete and resting on—

A. Bed-rock.

B. Timber and concrete caissons.

C. Timber grillages supported on piles.

D. Piles.

6. Braced steel piers resting on—

A. Bed-rock.

B. Masonry, brick, or concrete piers.

C. Cylinder piers.

7. Timber piers resting on—

A. Mudsills.

B. Piles.

Now in respect to which of these seven kinds of piers and which of their various supports it is best to adopt for any particular crossing, the engineer must use his judgment, which, however, may be aided by the following remarks that are based upon the author's experience: