334 Proceedings of the British Association. 
explain this popularly, Mr. Lubbock stated, that, however paradoxi- 
cal it might appear to persons not acquainted with the subject, yet 
true it was, that, although the tide depended essentially upon the 
moon, yet, any particular tide, as it reaches London, would not be 
in any way sensibly affected, were the moon at that instant, or even 
at its last transit, to have been annihilated; for it was the moon as 
it existed fifty or sixty hours before which caused the disturbance of 
the ocean, which ultimately resulted in that tide reaching the port 
of London. The author then exhibited several diagrams, in which 
the variations of the heights of the tide, as resulting from calculations 
founded upon the theory, were compared with the results of ob- 
servations. ‘The general forms of the two curves which represented 
these two results, corresponded very remarkably ; but the curve 
corresponding to the actual observations, appeared the more angular 
or broken in its form, for which Mr. Lubbock satisfactorily account- 
ed, by stating, that the observations were neither sufficiently numer- 
ous, nor sufficiently precise, from the very manner in which they 
were taken and recorded, to warrant an expectation of a closer con- 
formity, or a more regular curvature. When it is recollected that 
the observations are at first written on a slate, and then transferred 
to the written register, by men otherwise much employed, and 
whose rank in life was not such as would lead us to expect scrupu- 
lous care, it was not to be wondered at, if occasionally an error of 
transcript should occur, or even if the observation of one transit was 
set down as belonging to the next. When to these circumstances it 
was added, that the tide at London was in all probability, if not cer- 
tainly, made up of two tides, one having already come round the 
British Islands, meeting the other as it came up the British Chan- 
nel, it was altogether surprising that the coincidence should be so 
exact; and it was one among many other valuable results of these 
investigations, that it was now pretty certain, that tide tables con- 
structed for the port of London by the theory of Bernouilli, would 
give the height and interval with a precision quite sufficient for all 
practical purposes, and which might be relied on as sufficiently ex- 
act, when due caution was used in their construction, and the neces- 
and known corrections applied. In conclusion, Mr. Lubboc 
stated that the observations for the port of London had now been 
continued from the commencement of this century, and those for 
Liverpool, as we understood, about twenty-five years. 
