382 
MR. LUBBOCK ON THE TIDES IN THE PORT OF LONDON. 
generally to have but little effect on the tide. North-westerly gales raise the 
tide ; south-westerly winds depress it. 
Two maps are annexed to this paper, drawn by Mr. Walker; the one show- 
ing the time of high water on the coast of Great Britain, the other throughout 
the world, or at least in as many places as it has been ascertained. 
The following are the authorities from which these maps have been compiled. 
The Chart of the British Isles is taken from the observations and surveys of 
Messrs. M‘Kenzie, Spence and Murray on the South coast of England ; from 
those of Captain Hewett and Mr. Thomas on the East coast ; France and the 
North Sea have been copied from the Admiralty Charts ; the coast of Scot- 
land is from M c Ivenzie, Captain Huddart and the Admiralty Charts ; and 
Ireland has been drawn from the surveys of Captain White, Captain Huddart, 
Mr. Nimmo, &c. & c. 
In the Chart of the World, the Coast of France, Spain and Portugal is copied 
from the Admiralty Charts and the surveys of Tofino ; Africa from those of 
Captain Owen ; Newfoundland is from Captain Bullock ; Nova Scotia and 
the coast of the United States are from the Admiralty Charts ; South America 
and the west coast of North America have been copied from the Spanish Charts, 
and from the surveys of Captains King, Beechey, Vancouver, & c. &c. The 
coasts of Persia, India and the Indian Seas have been taken chiefly from 
Captain IIorsburgh’s Charts and Book of Directions ; Australia is from 
the surveys of Captain Flinders, King, &c. &c. 
It will be seen that the continents alter the direction of the cotidal lines, (I 
mean the series of points at which it is high water at the same instant,) and 
that the progress of the tide is not always from east to west : in the Atlantic 
it is from south to north ; so that it is high water at nearly the same time on 
the coast of Portugal and on the opposite coast of America. This remarkable 
circumstance is noticed by Bacon*. 
The map of the world is offered as a mere sketch, for our information on this 
subject is at present lamentably deficient. The map of Great Britain presents 
* De Fluxu et Refluxu Maris. Bacon’s Works, vol. ii. p. 81. “Idquenon fortuito notatum, sed de 
industria inquisitum atque repertum, aquas ad littora adversa Europae et Floridae iisdem horis ab utroque 
littore refluere, neque deserere littus Europae cum advolvantur ad littora Floridae, more aquae (ut supra 
diximus) ugitatae in pelvi, sed plane simul ad utrumque littus attolli et demitti.” 
