OBITUARY NOTICES. 
455 
change the sea-level in Boston harbor only about one foot. 
The effect of barometric pressure is apparently about one- 
half of its theoretic value and decidedly less than at Brest, 
Bristol, or Liverpool, but nearly the same as at London. 
After correcting for the effect of the winds and the barometer, 
there is left the above-mentioned annual inequality in the 
mean sea-level which is not explained by either of these 
meteorological influences. Some of the outstanding dis¬ 
crepancies are explained in Ferrel’s final report on the Bos¬ 
ton Tides in the Coast Survey Report for 1873 as due to the 
fact that at Boston the rising barometer and the westerly 
winds with clearing weather combine together to lower the 
sea-level and suffice to mask the effect of the inertia of the 
rising or falling water. 
A similar subsequent discussion of the tides in New York 
harbor and again of the tides in Penobscot bay, and finally 
of the tides of the Pacific coast, brings out the fact that the 
so-called retardation or age of the tide, namely, the delay 
in the times of the maxima of the tidal inequalities, is not, 
as was supposed by Whewall, simply the time required for 
the free tidal wave of the southern ocean to arrive succes¬ 
sively at the ports of the North Atlantic. This retardation 
is rather an apparent phenomenon due to the defects of our 
anatysis, w'hich has assumed that the same principles apply 
to tides in deep and in shallow water. The same memoir 
also shows that the same annual inequality that holds good 
for Key West, Brest, and Boston applies also to New York 
and Penobscot bay, and is apparently due to an annual 
change in the ocean currents, but is not wholly explained 
even by this. 
(13.) 1874.—The successive improvements in Ferrel’s form¬ 
ulae, and especially the fine series of observations in Penob¬ 
scot bay, enabled him to show “ why it is that satisfactory 
“ and consistent values of the mass of the moon have not in 
“ general been obtained from the semi-diurnal tides, for these 
“ relations are disturbed by the various shallow-water com- 
“ ponents which do not enter into the theory of deep-water 
