APPLICATIONS OF TIMBER. 193 



degree of skill, in balancing strains against each other, 

 so as to insure both steadiness and strength. The 

 principal fault in this celebrated bridge consisted hi 

 many of the timbers being of great length, so as 

 not to admit of being easily replaced in case of 

 decay. It was burned down by the French army in 

 the year 1799; and has since been replaced by a more 

 simple wooden bridge, in which the water-way is di- 

 vided into three parts by two piers, and the road is 

 said to be wider and more convenient. 



Several other wooden bridges were constructed by 

 Ulric Grubenman, by his brother John, or by the 

 two together. Of these, John built a bridge over 

 the Rhine, near Richenau, of two hundred and 

 forty feet span; and the two brothers erected another 

 of two hundred feet across the Limmat, near Baden. 

 Both these bridges resembled, in their general 

 framing, the bridge at Schaffhausen. Ulric, however, 

 constructed one somewhat differently; it was two 

 hundred and thirty feet span. In this bridge there 

 were no diverging braces. The abutments were 

 twenty-five feet high, and the arch between them was 

 a catenary, that is, the same form which a rope or 

 flexible chain assumes by its own weight, when hung 

 over two fixed pegs. This arch was of course in- 

 verted, in the same manner as the iron chain bridges 

 that have recently been constructed in this country; 

 and making allowance for the difference of materials, 

 and the mode of the junction, it may be fair perhaps 

 to consider it as the first chain bridge that ever was 

 constructed in Europe. The two catenarian arches 

 from which the roadway was suspended were formed 

 of beams of oak, in lengths of from twelve to fourteen 

 feet; there were seven thicknesses of them above 

 each other, and they were so contrived as to break 

 bond like masonry, so that there should never be two 

 vertical joints in the same section, and they were 

 strongly bolted and bonded together. Probably for 



VOL. II. 17 



