National Geographic : 1897 Dec
THE WASHING TON A Q UED UCT (Massachusetts) granite, the abutments are of Montgomery county gneiss, and the rubble arch, spandrils, and parapet are of Seneca sandstone. Contrary to the general impression, the space between the spandril and abutment walls is not solid, but contains several arches, built, as shown in the drawing, to effect a saving in masonry. Materials were transported to the bridge by boat via the Chesapeake and Ohio canal and Cabin John creek, across which a dam was built near the canal, and the pool thus formed was connected with the latter by a lock. On the south side of the west abutment of the bridge the fol lowing inscription is cut: Washington Aqueduct, Begun A. D. 1853. President of the U. S. Franklin Pierce. Secretary of War, . Building A. D. 1861. President of the U. S., Abraham Lincoln. Secretary of War, Simon Cameron. This inscription originally contained the name of Jefferson Davis, which was cut out in the summer of 1862 by the con tractor by order of the Secretary of the Interior, Hon. Caleb B. Smith, to whose department the aqueduct had been recently transferred. If forgetfulness of the bare historical fact as to who was Secretary of War at the time was the object sought by the erasure, the result has been a woeful failure, for the inherent curiosity of mankind is such that the erased name is more strongly impressed upon the memory of the visitor than would have been the case had it remained untouched. In concluding the description of the Washington aqueduct and its special structures, it is proper to call attention to another of its bridges, the bridge over Rock creek on Pennsylvania ave nue, as noted for its bold originality as is Cabin John bridge for its grand proportions. This bridge is unique among the aqueduct bridges of the world, in that the two 48-inch mains, through which now flows about one-half of the water used by the city, themselves form the arched ribs which support the roadway overhead. The span of this bridge is 200 feet and its rise 20 feet. At the time it was built it was the only one of its kind in the world, and it enjoys, it is believed, this distinction at the present day. It was much commented upon by European engineers, and was illustrated in many of the foreign scientific and engineering journals of the time.