MR. LUBBOCK ON THE TIDES. 
99 
eated by the observations ; but in order to render the agreement complete, it would 
be necessary to change the epoch by half an hour*. This remarkable circumstance 
also obtains in the London correction, as may be seen by reference to the plate which 
accompanies my last paper. 
The results contained in the Tables here given are laid down in diagrams, with- 
out which they could not be so readily understood ; but as they are similar in 
nature to those contained in my last paper, they do not require an extended de- 
scription. 
The calendar month inequality at Liverpool, considered as resulting implicitly from 
the corrections due to changes in the declinations of the luminaries and in the sun’s 
parallax, agrees generally with the equilibrium theory, and with the results deduced 
from the London observations given in my last paper. The diagrams in Plate I. 
show that the spring equinoctial tides are greater than the neap equinoctial tides, 
and that the neap solstitial tides are greater than the spring solstitial tides, confirming 
what is stated by Laplace in the Exposition du Systeme du Monde, 5 e ed., p. 83, and 
by Newton: “In quadraturis autem solstitialibus majores ciebunt sestus quam in 
quadraturis sequinoctialibus, eo quod Lunae jam in sequatore constitutse effectus 
maxime superat effectum Solis. Incidunt igitur sestus maximi in syzygias et minimi 
in quadratures luminarium, circa tempo ra aequinoctii utriusque. Et aestum maximum 
in syzygiis comitatur semper minimus in quadraturis, ut experientia compertum est.” 
Laplace says, “ Elies [les marees] augmentent et diminuent avec le diamtitre et le 
parallaxe lunaire, metis dans un plus grand rapport but the diagrams in Plate II. 
appear to confirm the truth of this passage only at neap tides. 
It is desirable to establish the laws which regulate the diurnal inequality in the 
height of high water in different parts of the globe ; at present the data are 
very insufficient. Mr. Whewell remarks, “that it would be easy to enumerate 
many actual cases in which the safety or loss of a ship has been determined by 
this inequality.” Mr. Whewell was the first specially to notice, in his examination 
of the results of the tide observations made on the coasts of Europe and America in 
June 1835, contained in the Philosophical Transactions for 1836, the changes which 
this inequality presents in passing from one place to another. 
This inequality depends chiefly upon the sign and amount of the moon’s declina- 
tion. The observations at London and Liverpool indicate no difference between tides 
corresponding to upper and lower transits, or between those corresponding to A.M. 
transits and transits P.M. six months afterwards ; hence in endeavouring to deter- 
mine the diurnal inequality at London and Liverpool, I have confounded in Tables XII. 
and XIII. the results corresponding to upper and lower transits, and those corre- 
sponding to A.M. transits and transits P.M. six months afterwards. I have also 
added to these those which ought, according to the preceding remarks, to differ only 
* Or, adopting Bernoulli’s views in other respects, the epoch of the correction for the height is not the 
same as that for the interval. 
