438 REPORT— 1840, 
Another portion of the sum placed at my disposal has been 
expended upon calculations and operations performed by Mr. 
Bunt. These calculations were in the first place directed to 
the determination of the form of the curve of rise and fall of the 
tides at Bristol. This determination was the more desirable, 
inasmuch:as calculations were in progress at the Admiralty 
(under my directions) for the purpose of determining the form 
of the curve of the rise and fall at Liverpool and at Plymouth. 
The results of these calculations have been laid before the Royal 
Society, and are now printed by them in the Philosophical 
Transactions, as the twelfth series of my Researches on the 
Tides. The accompanying communication from Mr. Bunt con- 
tains the result of his investigations on this subject. The thing 
principally discussed was the displacement of the summit of the 
curve of rise and fall; that is, the difference of the time of high 
water actually observed, and the time obtained by bisecting the 
interval between equal altitudes, before and after high water. 
The main object was, to refer this displacement to its proper 
argument. It was natural to suppose that it depended mainly 
upon the height of the tidal wave, and, consequently, upon the 
age of the moon; and hence would principally consist of a se- 
mimenstrual inequality. But by the discussions, it appears 
that there is, besides this fact, one which depends upon the 
solar parallax, and also others. This would lead, as Mr. Bunt 
remarks, to a suspicionthat meteorological causes are concerned 
in producing the result ; the subject, however, is as yet not free 
from difficulty. IT have also employed Mr. Bunt in other dis- 
cussions, with a view to further improvements in our knowledge 
of the laws of the tides, especially with reference to two points : 
—the determination of the best anterior epoch, or period, at 
which that anterior transit of the moon is to be assumed which 
governs the tide :—and the solar corrections for parallax and 
declination. The excellence of the Bristol observations made 
with Mr. Bunt’s machine, and of his modes of discussing the 
observations, induce me to believe that some progress may still 
be made in this inquiry ; but the investigation is not yet com- 
pleted. I have also taken the liberty of directing Mr. Bunt to 
perform an operation not precisely included in the terms of 
the grant made to me for the present year, but closely connected 
with it, and forming an almost necessary sequel to a large ope- 
ration performed at the expense of the Association in preceding 
years ; I mean, a repetition of the levelling of a portion of the 
level line in the neighbourhood of the recent landslip in Devon- 
shire. The southern extremity of the line leveled from the 
Bristol Channel to the English Channel is at Axmouth. When 
