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Some particulars relative to the Tides in the upper part of the 

 River Thames^ and of the obstructions caused hy the present 

 London Bridge. By P. Barlow, F.R.S., Mem. Imp. Acad. 

 Petrop., &c. (Communicated by the Author). 



Xjondon Bridge, which has for so many years bestrided the 

 Thames, is now doomed within a very short time to be remo- 

 ved, and a considerable change will be, there can be no doubt, 

 effected in the state of the River from the present site of the 

 Bridge upwards. It may not therefore be uninteresting to re- 

 cord some particulars relative to the present state of the tides, 

 and of the river, in order hereafter the better to compare the 

 change which the removal of the bridge may occasion. When 

 this question was before Parliament, I was summoned to at- 

 tend the Committee to state my opinion relative to some points 

 connected with these probable changes, and it Was on that oc- 

 casion that I collected together the several facts given in the 

 following pages, and which, if they should not be found to fur- 

 nish any present important information, may hereafter be refer- 

 red to as matters of interest by the curious inquirer. Some 

 doubts having been suggested as to the damage which might be 

 sustained by the wharfs. Sec. above bridge, by the rising of the 

 river above its present level at high water, and the exposure of 

 the sewers at low Water, the data here given are such as are 

 connected more particularly with these questions ; they con- 

 sist, 



1. Of the sectional area of water-way at the different bridges, 

 at various states of the tide. 



2. Of the hourly rise and fall of the tide, and the difference 

 of level at different times of the tide, immediately above and be- 

 low London Bridge. 



3. The rise and fall, and interval between the time of high 

 and low water, at Woolwich, and at several other places on the 

 river, ascertained by observations made on the same days. 



4. Experiments and observations made on the velocity of 

 the tide at ebb and flood at Woolwich, and other places on the 

 river. 



OCTOBER— DECEMBER 1826. D 



