Suspension Bridges and other Structures. 395 



Fig. 16. 



sets of divisions, and the oscillations will be less with the 

 four stays in figure 16, than with the four stays on the old 

 method, in the proportion of 4 to 5005, being nearly 1251 times 

 better than before. 



Case (4.) Any number of stays. Let the whole length of 

 the bridge be divided into 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 

 41, 43, 47, 51, equal parts ; taking as many of these dividing 

 numbers as there are stays, the result will be, that the power of 

 resisting oscillation will be found by multiplying by each other 

 all of the dividing numbers used. 



It is unnecessary to enter in this paper upon the practical 

 details which will immediately occur to the civil engineer, and 

 suggest themselves readily to the intelligent mechanical en- 

 gineer. The stays should be similar in construction to the 

 main chains of the bridge, l^^t much lighter, and each link 

 should be kept in the straight line by a suspending rod from 

 the chain, continued from the platform, so as both to keep the 

 stay in the best position for resisting oscillation, and to distri- 

 bute its weight more equally. 



The same principles which apply to a single arch apply to a 

 series of arches, either in a wooden structure, or extensive 

 stone arches, or a chain pier like those at Brighton, and that of 

 Trinity in the immediate neighbourhood. The arches should 

 bear to each other the porportion of some of the numbers in 

 the series of dividers already given, so as to prevent the propa- 

 gation of oscillations from one to another. 



Stays in platforms, viaducts, and all wooden structures, when 

 intended to prevent oscillations, should be placed at distances 

 not perfectly equal, but in the proportion of the series of num- 

 bers already given, and all structures intended to prevent oscil- 

 lation should be found on the same principle. 



John Scott Russell. 

 21 Co AXES Crescent, IQth Jan. 1839. 



cc2 



