SCHUYLKILL PERMANENT BRIDGE. gg* 



agonal ; the salient angles acute ; and pointing up and 

 down the stream.* 



The report also shews, how little service was afford- 

 ed by our most ingenious mechanics, out of the line of 

 their several trades. With the best dispositions, many, 

 as well mechanics as other citizens, suggested remedies 

 for misfortunes^ or supposed guards against them. 

 Some assisted in executing their ideas in both dams, 

 but not a solitary attempt succeeded. The Company 

 are not the less obliged ; nor is it any reflection upon 

 them, as they had as little experience in such undertak- 

 ings, as those whose duty compelled bold and hazard- 

 ous measures, on which, even professional men, versed 

 in hydraulic mechanism, w^ould not have risqued their 

 characters. 



* Hemlock timber^ (P'lnus Abies Americana^ Lin.) had near- 

 ly defeated the eastern dam : much of it was used, on account 

 of its cheapness. But it always gave way, when hard pressed ; 

 and its failure, at several critical times, was nearly fatal. The 

 belts (which serve to a da??!., the same purposes as hoops to a 

 cask^ frequently broke ; owing to their being of this wood, and 

 flinty, or curly, in spots. Straight grained he}}ilock, entirely free 

 from curl orf hit ^ is seldom to be found ; though some varieties 

 are better than others. But this timber never should be de- 

 pended upon ; either for strength, or durability. It was ex- 

 cluded from the zvestern dam. Some hemlock is very durable ; 

 but the appearance of this wood, is so generally alike, that it 

 is imprudent to risque the chances of hitting on the kind re° 

 quired for lasting, or strength. Perhaps there may be some 

 stages of growth, or time of felling, as it is with other woods, 

 more or less favourable to durabilit}-. 



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