62 Improvements of the Tort of London^ 



to tbofe who have not had an oportunity of confidering the 

 qualities of iron, or who have not carefully compared its 

 itrength with the itrength of the materials formerly ufed in 

 conftructing bridges. In great works it is proper we fhould 

 proceed with caution ; but the very principle of improvement 

 muft be wholly abandoned, if the demonftrations of fcience 

 and the evidence of practical knowledge are to be difregarded. 

 To thofe who will take the trouble of comparing the fpecific 

 gravity and the ftrength* of cafl: iron with thofe of ftone, it 

 will not appear extraordinary, that by ufing that metal, the 

 practice of bridge- building may be changed, and the open- 

 ings of archways made to extend far beyond what has hitherto 

 been attempted. The advantages to be derived from this prac- 

 tice are obvious, and become of great national importance in 

 every country where the free navigation of rivers is intimately 

 connected with its profperity. 



We have been led into the confideration of this fubject by 

 the information wc have received refpecting the plans for re- 

 building London bridge. Underftanding that there was a 

 plan for conftructing a bridge over the Thames of a Jingle 

 arch of caft iron, we have made particular inquiries, and 

 have authority to fay that the following is a correct ftate- 

 ment of the hiftory, principles, and plan of this defign : 



The manufactures, trade, and commerce of Great Britain 

 having increafed to an extent unparalleled in the hiftory of 

 nations, a great proportion of whieh is carried on through 

 the metropolis by means of the fine river upon which it is 

 fituated, and the important centre it forms for the commerce 

 of great part of the world; although this river forms an ex- 

 cellent channel to admit the intercourse of (hips of the largeft 

 burthen within a few miles of the city, yet, from the increafe 

 of the number and fize of the veflels frequenting the port of 

 London, great inconveniences and lofles have been experienced 

 in tranfacling the bufinefs connected with the fhipping. The 

 diftance at which the large (hips are obliged to lie, the con- 

 fufion of (hipping in the river, the lofs of time in loading and 

 discharging goods, the expenfe of lighterage, the frequency 

 of thefts, the delays and vexation experienced by the mer- 

 chant and manufacturer, have at laft given rife to propofi- 

 tions and plans to remedy thofe evils. On this great national 

 fubject, which embraces fuch a variety of objecls, opinions 

 have, of courfe, been various, and fome of them contradic- 

 tory : this produced much difcuffion while the bufinefs re- 

 mained with an open committee of the houfe of commons; and, 

 although much ufeful information was obtained, yet no project 

 appeared to be finally agreed on, and brought to maturity. 



This 



