124 Account of the Great Stispension Bridge of Fribowg. 



submit the measure to the consideration of engineers of different 

 districts. Various designs were accordingly offered, and the 

 Government of the Canton gave the preference to that of M. 

 Challey of Lyons, whose plan has since been executed under his 

 immediate superintendence. J 



The gateways at either end of the bridge are of Doric archi- 

 tecture, and are about 65 feet in height. The tops of their 

 arches are about 42 feet above the roadway, and the arches have 

 a span of 20 feet. The masonry of the gate is 46 feet in width, 

 and its thickness is about 20 feet; and, although the largest 

 blocks of the hard limestone of Jura were employed in this work, 

 iron cramps were used to complete the union of the stones, and 

 above 24 tons of iron were used for this purpose. 



The width of the valley of the Sarine at the point where the 

 bridge is built, or, in other words, the distance between the 

 inner face-work of the two gateways on either bank of the 

 river, and consequently the span of the suspended roadway, is 

 871 feet. It may be easily conceived that a good deal of doubt 

 was entertained as to the propriety of trusting to a span of so 

 great an extent, and the idea of suspending the bridge at the 

 middle at first occurred to M. Challey as the best mode of form- 

 ing the communication. On weighing the difficulty, however, 

 of obtaining a solid foundation for a pier 220 feet in height in 

 the bottom of an alluvial valley, he soon relinquished this idea ; 

 and the bridge has therefore been constructed with a single span 

 of 871 feet. 



The roadway is suspended in the manner now universally 

 known, by four cables of iron wire * passing over the upper part 

 of the gateways. Each cable consists of 1200 wires, each about 

 -r^i5th inch in diameter, and 1140 feet in length. To avoid the 

 difficulty of moving these heavy cables, each wire was brought 

 separately to its place, and they were united on the spot by the 

 workmen, who were suspended during the work. We are happy 

 to add, that no accident of any kind occurred during this opera- 

 tion. It is calculated that the four united cables are capable of 

 sustaining a weight equal to 2946 tons. 



• It is not perhaps generally known that in all the suspension bridges in 

 France, ropes formed of wires are employed, instead of the solid links used 

 in F.ngland. 



