rear of the pier near the top. By screwing up on these adjustments the tops of the two piers were moved back a little. Provision is made for future scour by leaving some spare chain beyond the point at which the rod takes hold, so that one chain at a time can be loosened, lowered, and retightened. These East Omaha bridge-piers will probably last a long time yet, although when they were put in no one anticipated that they would be needed for more than eight years.

In sinking piers the greatest care should always be taken to start them in exact position and to keep them there. The instant it becomes evident that a pier or cylinder is getting out of correct position, it should be moved back, even if it be necessary to stop the sinking entirely until the true position be recovered. Generally it is feasible to build a frame of piles and heavy timbers around each pier or cylinder, so as to guide it to exact position at all times, barring a slight springing of the piles, which, however, can generally be guarded against.

Some sixteen years ago the author had occasion to sink four eight-foot cylinders in the Des Moines River by open dredging to bed-rock, so as to form a single pier, the axes of the cylinders being located on the corners of a twenty-four-foot square. Unfortunately the author in making the design, owing to inexperience, had provided no allowance for variation of location. The foreman of construction informed him that it was absolutely impossible to sink those four cylinders so correctly that the struts would fit between their tops; consequently the author was compelled to undertake the superintendence of the work himself. He built a strong frame of piles and heavy timbers, all thoroughly braced, around the space to be occupied by each cylinder, cutting out the horizontal timbers to fit the curve of an eight-foot circle, and even gouging out places for the rivet-heads to pass. One of these horizontal guides was located close to the surface of the water, and the other some nine or ten feet higher. The cylinders were dropped into these guides and sunk to bed-rock. After all four cylinders were in place, and partly filled with concrete, the struts were inserted between their tops, and were found to furnish  a  driving   fit.   This   result   was,    perhaps,    due   as   much   to   good