356 ON SUSPENSION BRIDGES. 



1st. Suppose the part or link BC horizontal, 

 the sum of the weights supported by the vertical 

 rods hanging from C e fgy and sustaining part 

 of the road-way with any thing upon it, is as 

 the tangent of the inclination of gh to the 

 horizon. 



2nd. The weight borne at any joint g is as 

 the difference of the tangents of inclination of 



the links gh ^nAfg to the horixon. 



3rd. The strain on any link, as gh, in the 

 direction of its length, is as the secant of its 

 angle of inclination to the horizon. The 

 strength of the link ought therefore to be in 

 that proportion. 



The demonstration of these and other pro- 

 perties of this curve are given by Hutton and 

 most writers on mechanics. 



It is evident from above that if all the angles 

 of inclination of the links be given, with one 

 of the weights or with the tension of one 

 link, we shall be enabled to find all the other 

 weights, and the tensions of all the links. 



3. These properties too would equally apply 

 to a flexible chain alone, if the weights of its 



