cm 
On the Tides of the Western Coast of the United States. 5 
It should not be forgotten that, the observations having been 
made in successive years in the same month, the moon’s age and _ | 
declination, and the sun’s declination are not very different, sand 
the sun’s declination is nearly the same on the corresponding days. 
The diurnal inequality obtained by the usual methodsis given 
in the annexed table, No. 2. The two series are’ combined by 
taking the averages for the days on which the declinations corres- 
pond in the two series. Each average is thus the mean of four 
individual results. 
These numbers are projected on diagram C, where the ordinates 
correspond to the intervals for one curve and to the heights for 
the other, and the abcisse to the tidal days for both. Notwith- 
standing the small number of observations, the curves can be 
traced with tolerable certainty and follow the general law of the 
inequalities. 
Each curve shows an inequality increasing and decreasing with 
the moon’s declination nearly, crossing the zero line at or near the 
zero of declination, and reaching a maximum or minimum at the 
maximum of north or south declination. The observations do 
not furnish sufficient evidence to decide positively that the epochs 
of the several inequalities coincide with those of the declination 
or otherwise. On the average they are about half a day before 
the corresponding declinations. : 
The inequality in the height of high water and in the interval 
of low water increase and decrease together, and so of the ine- 
quality of high water and height of low water. 
The declination of the moon and the inequality in interval of 
high water and in height of low water have the contrary sign ; the 
reverse is the case with the other two inequalities. 
The inequality in the height of low water is in general greater 
than that of high water, exceeding it when at the maximum in 
the proportion of two to one, (nearly 1‘9 to 1). The same rela- 
tion exists between the maximum inequality in interval of high 
water as compared with that of low, (1°7 to 1). : 
The maximum inequality in the height of low water is 3°60 
feet, and of high water 1°85 foot. The maximum inequality of 
Interval of high water, as shown by the curve, is lh. 53m., and 
of low water lh. 7m. 
I am indebted to Mr. Heaton, of the tidal party, for the decom- 
fom some trials which I have made, these decompositions may 
be improved, they are, nevertheless, of great interest, and show 
‘well the causes of the forms assumed by the curves of diurnal in- 
equality in height and interval, and for high and low water and 
their relations. When observations now in progress on the 
Western coast shabl have given additional results, I propose to take 
