AND ON THE DIURNAL INEQUALITY. 
13 
vation, which deprives the results of their value. We should not be justified in dis- 
turbing any previous determinations of the “establishment,” on the ground of new 
observations of this kind ; although it is true, that for aught we know, the previous 
determinations may rest on no better data. To show the extent to which this may 
go, I will give the values of the lunitidal intervals as they result from some recent 
observations on the west coast of America. 
Lunitidal intervals observed. 
Place. 
Lat. S. 
Long, 
Interval. 
Range. 
Observed. 
Greatest. 
Least. 
Greatest. 
Least. 
h m 
h m 
ft. 
ft. 
Callao 
12 3 
7 25 
3 0 
2 
1 _ 
12 tides. 
Puna Island 
3 37 
6 16 
3 24 
13 
ll“ 
15 tides. 
North. 
Panama 
8 57 
4 0 
1 48 
15 
9 
17 tides. 
Nicoya 
9 56 
3 50 
1 24 
10 
6 
40 tides. 
Reafejo 
12 28 
3 20 
1 10 
13 
1 
31 tides. 
Acapulco 
16 50 
3 0 
1 12 
li 
1 
2 
10 tides. 
Magdalena Bay 
24 38 
9 30 
5 24 
6 
3 
13 tides. 
I have added the range of the tide, that it may be seen whether the case was one 
in which much accuracy was to be expected. It is evident that at such places as 
Callao, where the tide ranges only from half a foot to a foot and a half, or two feet, it 
must he very difficult, especially by any rude apparatus, to determine with any accu- 
racy the time of high water ; accordingly we see that the interval, as observed, varies 
nearly four hours and a half. But at a place where, as at Panama, the tide ranges 
from nine to fifteen feet, it is more surprising to find the lunitidal interval varying 
as much as 2^ 12™. I am not however disposed to question the correctness of these 
observations; for the diurnal inequality, added to the semimensual inequality, may 
make the difference as great as this : and it will be observed that the mean result, 
54™, would give an “establishment” about 24™; not differing much from the 
establishment given by Mr. Lloyd*, namely 3 *^ 20™. 
31 . I shall now proceed to give the tide-hours for the coasts of the Pacific, accord- 
ing to the best accounts which I find, judging them in the manner I have described. 
After noticing the course of the tide near Cape Horn, I shall follow it along the 
whole western coast of America, till, in the north, we reach the Aleutian Isles ; and 
then, following this chain of islands, to the shores of Kamtschatka. I shall then con- 
sider the islands in the central parts of the Pacific, and proceed from them west- 
ward, according to my materials. 
I have already, in my first Essay, shown that round Cape Horn, the tide-wave has 
an easterly motion. Thus, as I have there said, according to Captain King'|', at Cape 
Pillar it is high water at I** on the day of full and change ; at York Minster, 5° of 
longitude to the east, it is at 3** ; at Cape Horn, 3° further east, it is at 3i>> ; in Good 
* Philosophical Transactions, 1830. f Sailing Directions, p. 96, and Table, pp. 13, 14. 
