ON SUSPENSION BRIDGES. 



365 



and the recent ones of Whewell, Gilbert and 

 others, little is left to be done in a scientific 

 point of view. Hence to their successors, it will 

 be like searching over a well reaped field, where 

 scarcely an ear can be gleaned. 



The following pages will therefore be in a great 

 measure devoted to the solution of a few problems 

 rising out of this new application of the catena- 

 rian curve ; seeking principally for the forms of 

 the curves made by the chains under different 

 circumstances. 



2. First premising that the general form of 

 the curve A B C D 



F?G. I. 



which we will suppose to be the main chain 

 supporting one side of the bridge, (A and D being 

 the points of suspension, and E F the road-way) 

 is a catenarian polygon, some of whose properties 

 are as follow : 



2 y2 



