THE THAMES TUNNEL. 141 



parallel plane with the upper chains, diverge from them near the points 

 of support. The two bars of the inverted chains, and the lower suspen- 

 sion rods, are fastened together ; the upper part of the suspending rod 

 goes through the corresponding beam close to one of the upper rods, and 

 is fastened by a screw to its head. The last bar of the inverted chain 

 goes through the whole thickness of the masonry of the central, pier of 

 the bridge, and on coming out is set in a large plate of cast iron; thus a 

 great part of the pier has to support the great strain or tensions 

 which the inverted chains must experience during storms, and when the 

 wind blows upwards. The same system is used to attach the other 

 extremities of the inverted chain to the abutments ; these inverted, or, as 

 they may be called, stay chains, have been found fully to answer the 

 purpose for which they were intended. 



THE THAMES TUNNEL. 



This stupendous attempt this gigantic effort of art to triumph over 

 nature, was commenced in 1824, under the superintendence of Mr. Brunei, 

 senior, the celebrated civil engineer,whose design has been strictly adhe- 

 red to, and whose scientific perseverance has successfully combatted the 

 most unparelleled difficulties. 



Two abortive attempts were made to form a Tunnel under the Thames, 

 one in 1799, at Gravesend, and the other in 1804, from Kotherhithe to 

 Limehouse, both of which were very soon abandoned. 



Tbe site of that which we shall endeavour to describe is most admira- 

 bly selected, and is perhaps the only spot between London Bridge and 

 Greenwich where such a roadway could be attempted, without interfering 

 essentially with some of the great mercantile establishments on both sides 

 of the River, being'situate in a very populous and highly commercial 

 neighbourhood, and where a facility of land communication between the 

 two shores is very desirable, and must of necessity be most advantageous, 

 not only to the immediate neighbourhood but also to the adjacent 

 counties. 



Mr. Brunei began his operations by making preparations for a shaft 

 50 feet in diameter, which he commenced at 150 feet from the river on the 

 Surrey side; this he effected by constructing first on the surface of the 

 ground a substantial cylinder of brick work of that diameter, 42 feet in 

 height, and 3 feet in thickness. Over this he set up the Steam Engine 

 necessary for pumping out the water, and for raising the earth to be taken 

 from within the cylinder, and then proceeded to sink it en masse into the 



