362 



NATURE 



\_August I, 1878 



measuring 27 feet in the longest, and 16 feet in the 

 transverse direction, is put on the foundation, filled with 

 concrete, and carried up solid to high water, where it 



has a cope 5 feet thick. For the 162 and 130 feet spans 

 on the north side the construction is similar to that 

 adopted for piers 20 and 27, while the shorter spans in 



Fig. I. — Secti m of river, iror'.cntal s:ale 2,000 feet tJ i inch. Vertical scale 50 feet to i inch. 



the curve are supported by columns set in 6-feet cylin- 

 ders sunk to the required depth and filled up with 

 concrete. 



No Staging to be Used in the Construction. 



The change in the nature of the river bottom, the 

 great height at which the bridge had to be constructed 

 and the heavy gales which are prevalent in this part 



of the country made it necessary from the beginning to 

 depart from the rules generally laid down for the con- 

 struction of such works. The erection of scaffolding 

 and staging was by these circumstances rendered im- 

 possible ; and a series of operations were substituted for 

 these old methods which by their success proved to be 

 great improvements, and must have great interest to 

 engineers and others less directly connected with such 



Fig. 2. — Floating and sinking p.ers. 



undertakings. As a rule the building operations were 

 entirely conducted on shore, and for this purpose it was 

 necessary to make preparations which took up the best 



part of the first year. In addition to the ordinary landing 

 jetties, workshops, and stores, special arrangements had to- 

 be made for building the piers and erecting the girders in, 



