ISt Mr. White's Design for the New London Bridge, 



at London Bridge, differing only from rapids as generally un- 

 derstood, on account of its double action, viz. upwards and 

 downwards according to the state of the tide whether ebbing 

 or flowing ; the ebbing tide producing the more violent rapid, 

 from two causes, the one an increase of the water from the 

 upper country, the other the greater ease of discharge from the 

 widening of the river and its greater depth towards its mouth. 



The City of London has most judiciously improved the 

 rapids of the river upwards as far as their conservancy of the 

 navigation extends, by constructing locks and weirs. 



It seems somewhat singular that the improvement of the 

 rapid at London Bridge should not have been publicly dis- 

 cussed otherwise than by investigating the question whether 

 the removal of the dam of the Bridge itself were a safe and 

 prudent measure. 



Having been much impressed with the necessity of an 

 ample consideration of the measure in all its bearings, I vi- 

 sited Holland in July last, conceiving that before I communica- 

 ted my sentiments on the subject, it would be desirable I should 

 make personal observations upon the large Dutch sluices, 

 particularly that of Catwyk, which is situated at the ancient 

 discharge of the River Rhine into the sea at a part ot the 

 coast where the ocean is much agitated, and where there is 

 much difficulty of approach. The lockage I found to be of a 

 different construction to that of the locks in England, but 

 adapted to the passage of vessels, and easily worked. 



By the determination of the Committee to prepare plans 

 for rebuilding London Bridge, it must be obvious that the in- 

 tended scheme of a five-arched bridge is not calculated on a 

 system ot regulating the tide, but on the contrary, favours the 

 conclusion that the removal of the dam of London Bridge is 

 the more desirable step, as its reconstruction will afford a 

 water way of 690 feet, the minimum prescribed by their pro- 

 spectus for designs. 



I am of opinion that the fears entertained by many per- 

 sons of the increase of the height of spring tides in the river 

 above the bridge are greater than they reasonably ought to 

 be, because no alteration of the river at London will increase 

 the height of the tide at the Noi-e, which height when ex- 

 cessive is caused by sudden changes of the wind, and which 

 in its endeavour to equalize itself, flows up the channel of the 

 river, and so causes extraordinary high tides therein. An op- 

 posite effect is produced by the wind, causing extreme low water 

 in the river, especially when there is little upland water. This 

 extreme low water is probably more detrimental to the conve- 

 nient navigation of London; for it is a very common complaint 



with 



