820 Transactions of the American Institute. 



people used only ropes or common chains, fastened to trees, and 

 the path was directly on the catenary, without suspended floor.* 



The development of the art of bridge-building is showing and 

 proving how deeply James Finley had studied his task, and how 

 much we owe to him. 



The principal features of his invention consisted in the appli- 

 cation of artificial stone abutments, in the introduction only of two 

 chains, one at each side of the bridge, the links of which were as 

 long as the distances between the cross-bearers or joists. Finley 

 applied one-seventh of the spans for the deflections of cables, intro- 

 duced suspension rods and stirrups to support the joists, and 

 arranged the anchor chains at the same angles as the main chains, 

 to avert powers acting to throw down the piers. 



The most interesting of the novelties, and one upon which Finley 

 apparently laid a great value, was the arrangement for distributing 

 the load over a great extent of the bridge, thereby aiding to divide 

 it over many suspenders, and to stiflen the otherwise movable floor 

 against change of shape. 



His specification reads as follows : 



" To bind and connect the whole that they have the same efi*ect 

 as a platform of one piece, four or more joists will be neccessary 

 for the upper tier — to extend from end to end of the bridge; each 

 will consist of more than one piece, the pieces had best pass each 

 other side by side, so that the ends may rest on difierent joists on 

 the lower tier. The splice will then extend from one joist to 

 another of the lower tier, and must be bolted together by one bolt 

 at each end of the splice. The planking floor is laid on the upper 

 tier." 



Herewith the inventor formed strong beams, continuous from one 

 end of the bridge to the other, and the continuity itself gives the 

 utmost certainty, that these beams, which were no directly bearing 

 parts, had the aforesaid important object, to stiflen the floor, pre- 



• At the discovery of America similar constructions were found theie. 

 Humboldt found in the year 1802 a suspension bridge across the river Chambo, in Pern, 

 the ropes being three feet thick, made of roots of the Agave Americana. The span was 

 forty feet. 



In the year 1515 the Landsknechte, a kind of regular troops (Germans and Switiers), 

 built a rope-bridge across Padns river, in Italy, which they passed with artillery. 



In the year 1595 Admiral Coligny, in France, made a rope-bridge near Poitier. 



In the year 1734 the army of the Palatinate of Saxony, in Germany, built a chain 

 bridge across the Oder river near Glorywitz, in Prussia. 



The bridge across the Tees in England (1741), seventy feet long and two feet wide, was 

 like those constructions in China and Thibet, having chains fastened to timbers, the planks 

 laid on them directly. 



