SCHUYLKILL PERMANENT BRIDGE. 4^1 



sonry with much attention we found to our great satisfaction, 

 that there had not been the least aheration in the work by any 

 accident. It had not settled an hair's breadth ; but stood firm 

 on its foundation, which we can now pronounce perfectly good, 

 sound, and immoveable. We were agreeably struck with the 

 perfect state of the v/hole masonry ; which does great credit 

 to Mr. Vickers the master mason. The tarras mortar used on 

 the exterior is as hard as the stone ; and the common mortar of 

 the interior, as dry and indurated, though covered with water 

 four months, as any cement, exposed in masonry to the open 

 air for twelve months." 



" We mention for the instruction of those who may have oc- 

 casion to build where water covers or flows round the work, 

 that rich mortar should never be used. Our common cement 

 is composed of three parts sharp, clean, coarse sand, and one 

 part lime. Sand is thrown into a bed of thin wash of slacked 

 lime, and agitated till every grain is coated with lime, it then 

 receives additions of sand till brought to its proper consist- 

 ency for use. The grout is fluid, but composed of the like 

 proportion of materials. The mortar used in the foundation 

 once intended for a pier, near the eastern toil house, but aban- 

 doned as a pier, and now usefully employed, as the end of our 

 wing walls, was covered more than a year with water. We 

 had occasion to take part of it up. The mortar, having been 

 improperly made rich, was friable, and had not the least tena- 

 city or binding quality. The tarras mortar is composed of one 

 part tarras, two parts lime and three parts sand." 



" The western pier is now completed to the same height, and, 

 except in depth, of the same dimensions with the eastern pier. 

 The span between these piers is 187 feet 6 inches, from the 

 piers to each abutment the span will be 150 feet each. No 

 formidable difficulties have occurred in the work of the present 

 season ; and every thing has been conducted to our satisfac- 

 tion." 



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