824 Proceedings of the British Association. 



posed, the lines of equal level would run, suppose from Bristol to 

 Ilfracombe in one direction, and from Bristol to Lyme Regis in the 

 other, and by these a common standard of level would soon be ob- 

 tained for the entire coast. — Professor Sir William Hamilton rose 

 to express the sincere pleasure he felt at the masterly expositions 

 of jNlr Lubbock and Professor Whewell. One conclusion to which 

 Mr Lubbock had arrived was to him peculiarly interesting, viz. 

 that by which it appeared that the influence of the Moon upon the 

 tides was not manifested in its effects until some time after it had 

 been exerted, for a similar observation had recently been made by 

 professor Hansteen respecting the mutual disturbances of the 

 planets. — Mr Lubbock rose to say, that the agreement between the 

 results calculated from the theory of Bernouilli and those obtained 

 from actual observation, were much more exact than Professor 

 Whewell seemed to imagine ; in truth, so close was the agreement, 

 that they might be said absolutely to agree, since the difference 

 was less than the errors that might be expected to occur in making 

 and recording the observations themselves — Mr Whewell explain- 

 ed that he wished to confine his observations to the Bristol tides, 

 as these were the observations to which he had particularly turned 

 his attention ; and, with respect to which, he should be able, at the 

 present meeting, to exhibit diagrams to the Section, which he felt 

 confident would amply bear out his assertions respecting these 

 tides — Mr Lubbock stated, that so near, indeed so exact, had been 

 the coincidence between the observations made at London and 

 Liverpool, and the theory, that he was strongly inclined to believe 

 that that coincidence would be found at length to be universal. — 

 Professor Stevelly inquired, from Mr Lubbock, whether he did not 

 think it quite possible that local causes might exist, which would 

 be fully capable of producing the deviations from the theory of 

 Bernouilli ; as, for instance, in the case of Bristol, so ably insisted 

 upon by Professor Whewell, where the causes of the extraordinary 

 elevation are the land-locking of the tide-wave as it ascends the 

 narrowing channel, and the reflexions of other tide-waves from se- 

 veral places. Now, particularly in the case of reflex tides, may it 

 not so happen, and does it not," in fact, happen in several places, 

 that they bring the actual tide to a given port at a time very dif- 

 ferent from that at which the influence of the Moon and Sun, if 

 unimpeded, would cause it to arrive, and thus separate, as Profes- 

 sor \yhewell had stated, the origin or epoch of the variations due, 



