above and hehw London Bridge. 51 



has the least section of the other four bridges at high water, 

 and this again causes an accumulation below bridge, but by no 

 means so great as in the former case. 



The effect of this blockage on the hourly rise and fall of the 

 water at the bridge is shewn in the following table : 



% TABLE of the Ebbing and Flowing of the tide at Londcm 

 Bridge, taken above and below on the ^9th of July 1821. 



Low Water 50 minutes past 

 9 o'clock in the Morning. 



High Water 35 minutes past 

 2 o'clock in the Afternoon. 



7 Hours and 59 Minutes 18 10 



By means of this table we readily find the head of water 

 above and below bridge at each successive hour of the tide, 



d2 



