344 THE WASHINGTON A Q UED UCT 



(Massachusetts) granite, the abutments are of Montgomery county 

 gneiss, and the rubble arch,spandrils, and i)arapet are of Seneca 

 sandstone. 



Contrary to the general impression, the s}»ace between the 

 spandril and abutment walls is not solid, but contains several 

 arches, built, as shown in the drawing, to effect a saving in 

 masonr3\ Materials were transj)orted to the bridge by boat via 

 the Chesapeake and Ohio canal and Cabin John creek, across 

 Avhich a dam was l)uilt near the canal, and the i)ool thus formed 

 was connected with the latter b}' a lock. 



On the south side of the west abutment of tlie bridge the fol- 

 lowing inscri^ition is cut : 



Washington Aqueduct, 



Begun A. D. 185;i President of the U. S. 



Franklin Pierce. Secretary of War, 



— . Building A. D. 1861. 



President of the U. S., Abraham Lincoln. 

 Secretar}^ of AVar, 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 Secretar}^ 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 tlie 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 originalit}^ 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 Avhich now flows 

 about one-half of the water used b}' the city, themselves form 

 the arched ribs which sujiport 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 b}^ European engineers, and was illustrated in 

 manv of the foreign scientific and engineering journals of the time. 



