W. Ferrel—Meteorological effects upon the Tides. 343 
In taking the averages in the last columns regard was had to 
the number of observations. The average barometric pressure 
is 30-007 inches. If, therefore, we put p for the pressure be- 
longing to the average of any of the groups of observations, 
we shall have for the correction of the height of the tide 
(80:007—p)C, in which C is a constant to be determined from 
observation. This expression put equal to each of the average 
residuals in the last column, reduced to inches, with the corre- 
sponding pressures or values of p, gives seven equations for 
By comparing the residuals of rising barometer with those 
of falling barometer in the preceding table, it is seen that there 
is a perceptible difference near mean barometer, and that con- 
sequently the sea-level when the barometer stands at the mean 
and is rising is a little lower than when it stands at the mean 
and is falling. This difference, however, is very small, and 
indicates that the sea, under the average rate of the change of 
ercnetng pressure, very nearly assumes the condition of static 
um. 
equilibri 
for the value of this constant at Brest. Mr. Bunt, also, from a 
diseussion of the residuals between theory and observations for 
jm Sb ub- 
bock found 11-1 for Liverpool, but at London i found that 
the water rises 6°3 inches for a depression of 0-90 of an inch of 
the mercury. (Phil. Trans., 1836, p. 11.) This gives only 
