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



" The City," I fear, do not proceed in the wisest possible 

 way with regard to this important edifice. 



I have the honour to be, Sir, yours very faithfully, 

 Royal Military Academy, Olinthus Guegory. 



March 13, 1823. 



Observations suggested by the perusal of Mr. John White's 

 Paper on the Waterfall nnder London Bridge, and of 

 his general Retnarks on Designs for London Bridge. By 

 Olinthus Gregory. 



In reference to the first of these, I have long felt surprised, 

 as Mr. White seems also to have done, that in the various 

 proposals for erecting a new bridge, it seems scarcely evei", if 

 at all, to have been thought worth inquiring how far the river 

 itself may be improved or injured by peculiarities in the struc- 

 ture that shall be adopted. 



My opinion has long been, that whether the number of 

 arches be five or seven, it would be by no means difficult to 

 adopt such a system of lockage, by sluices under the several 

 arches (sometimes to be all open, at others all shut, at others 

 part open, the rest shut}, as would serve greatly to improve the 

 state of the river, especially above Bridge, by removing de- 

 posits of sand and filth, and giving greater uniformity to the 

 bed of the river than it has, perhaps, possessed for centuries. 



It would be easy to elucidate the comparative effect of dif- 

 ferent schemes, by models constructed " to scale," in which 

 water should be conveyed mechanically with assigned velo- 

 cities through a channel in which obstacles precisely analo- 

 gous to the piers and sluices should be placed ; and the ope- 

 ration of the moving stream (whether upward or downward) 

 upon artificial sand or mud banks might be shown. 



I have heard nothing but very vague accounts of the sluices 

 of Catwyk, of which Mr. White speaks ; and therefore am 

 incompetent to speak of the way in which sluices at the pro- 

 posed new bridge might be assimilated to it. 



With regard to Mr. W^hite's questions, I should be inclined 

 to answer the first in the affirmative; the second in the affir- 

 mative ; the third, negative ; fourth, affirmative ; fifth, nega- 

 tive; sixth, answer not partial. 



The questions, however, deserve an ample consideration; 

 and I am glad to learn that Mr. White's ideas on a subject 

 so momentous are nearly matured. 



I am quite of opinion with Mr. White, that the fears enter- 

 tained by many persons as to the increased height of tide 

 above the bridge, if the present structure were removed, are 

 in a great measure groundless. The reasoning of Mr. Robert- 

 son 



