SCHUYLKILL PERMANENT BRIDGE. 41 



sonry with much attention we found to our great satistaetion, 

 that there had not been the least alteration 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 whole 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 v/ater 

 four montiis, 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, coai-se sand, and one 

 part lime. Sand is thi-own 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 me foundaaon 

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

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

 wing walls, vi'as covered more than a year with Avater. We 

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

 iniproperiy made rich, was friable, and had not tiie least ter^a- 

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

 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 w^ith the eastern pier. 

 The span bet\veen these piers is 18/ feet 6 inches, from the 

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

 formidable difncultics have occurred in the work of the preseiir. 

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

 tion." 



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