[ 379 ] 
XXI. On the Tides in the Port of London. By J. W. Lubbock, Esq., 
V.P. and Treas. R.S. 
Read June 16, 1831. 
I HAVE the honour to present to the Society a discussion of observations 
of the tides made at the London Docks, in the form of various Tables, which 
show the time and height of high water, not only at different points of the 
moon’s age, but also for the different months of the year, for every minute 
of the moon’s parallax, and for every three degrees of her declination. This 
work has been accomplished by Mr. Dessiou of the Admiralty ; but for the 
arrangement of the Tables, and the methods employed, I alone am responsible. 
The tides take place in the river Thames with extreme regularity, and, as 
the rise is considerable*, the observations are made with facility. Those upon 
which the annexed Tables are founded are made at the entrance to the London 
Docks ; the time of high water, or the time when the water has just made its 
mark, is there noted on a slate by the watchman on the pier-head, generally 
only to the nearest five minutes ; this is afterwards copied in a book kept for 
the purpose by Mr. Peirse. I am enabled, through the kindness of Mr. Solly, 
the worthy Chairman of the London Dock Company, to present to the Society 
the books containing the observations which serve as the foundation of 
Mr. Dessiou’s Tables. These observations are not made with sufficient care ; 
but they are valuable from the extent of time during which they have been 
carried on, as they were instituted soon after the opening of the Docks in 
1804, and have been continued without interruption to the present time. I am 
not aware of any series of observations of the tides so extensive, except that 
made at Brest by order of the French Government. Mr. Peirse informs me 
that the observations of the night are generally more correct than those of 
* I believe about nineteen feet. I am not however able to speak with precision, not having yet been 
able to examine the observations of low water. 
