OF THE COUNTY OF TYRONE. 1*7 



them funk fufficiently deep. More bridges, pipes, and 

 gullets have given way through this caufe, than through 

 all other caufes put together. In clayey and Tandy fitua- 

 tions, the courfe of the river or brook is perpetually 

 changing ; therefore too much precaution cannot be 

 taken to guard againfl accidents, that frequently arife 

 from fuch caufes. Where the current is rapid, there 

 the more care fhould be taken in finking deep ; but fuch 

 files for bridges fhould be avoided as much as poffible. 



Every day's experience {hews us, that bridges arc 

 much more fecure in dead or fmooth running water, 

 than when conftru&ed on fords, or near them, and 

 efpecially upon the upper fide. 



Bridges are, in general, built too narrow. The fink- 

 ing of foundations, centering, and mafon-work, between 

 a bridge of twelve feet wide, and one of eighteen feet, 

 bear not the fame proportion, of two to three, in point 

 of expence; that is, if a bridge, twelve feet wide, 

 fhould coft aoo/., it does not follow, that one, 

 eighteen feet wide, fhould coft 3007. ; this every per- 

 fon, the leaft converfant in bridge-building, mufl 

 know. 



In this county, it is only throwing away public 

 money, to introduce cut-flone coping on the battle- 

 ment, as the country people carry it away, and few of 

 the road-overfeers give themfelves any further trouble 

 about it. Stones, placed edgewife, of about a foot 

 high, and reaching quite acrofs the wall, are prefer- 

 able 



