320 REPORT—1904, 
Mr. Roberts has been good enough to send to the Committee, for the pur- 
pose of their present report, the following communication :— 
The Harmonic Analysis of the Tides at George’s Pier, Liverpool, for 1902. 
The following is the Analysis of 8, and M. Series of Liverpool, 1902 :— 
A (Mean Tidal Range) = 4-952 feet above O.D.S. 
a f H—3:188 feet M pre feet 
“2 « —11° 32’ “2 | « —326° 45’ 
S H—0:043 feet M H—0'111 feet 
4 { Kk —307° 4’ 3 | « —319° 0’ 
M { H—0'657 feet 
4 |on —244° 2! 
N.B.—The ‘ «’s are referred to Green- M { H—0'180 feet 
wich Meridian, as before. 6 | « —353° 6’ 
8 | « —248° 6! 
These figures are subject to revision, but can be taken correct for present com- 
parison. I have found a few misreadings of the Tide Gauge Diagrams; it is possible 
that there may be a few more, but I have not time now to go thoroughly again 
through all the figures. 
It will be seen that the above are almost the exact means of the previous two sets 
of three and four years, previously analysed; so that it may be assumed that the 
tides at George’s Pier have undergone scarcely any change during the last forty years. 
Eltham, August 4, 1904. 
Comparison of Tidal Diagrams of Different Periods. 
The Marine Surveyor, in addition to the Register of the Liverpool 
Tides for 1902 dealt with by Harmonic Analysis by Mr. Edward 
Roberts, was good enough to place at the disposal of the Committee a 
number of tidal curves, taken by the various self-registering gauges 
established by the Mersey Docks and Harbour Board, at different points 
throughout the tidal portion of the river, from the Bar to Warrington. 
A part of these tidal curves, limited in number, owing to shortness of 
time, were selected by the Secretary for comparison. 
The several periods for comparison being 1903 as representing the 
present dredged state of the Bar, and the improved conditions of the tidal 
flow in the river ; 1893 as presenting the conditions immediately before 
those improvements were commenced ; and 1874 as representing a still 
earlier period. When, as it happened, tidal observations had been carried 
out under the persona] superintendence of the Secretary on certain tides, 
at points in the higher reaches of the river where self-registering gauges 
have since been established. These results, together with the records of 
the two then existing Mersey Docks and Harbour Board gauges, at 
Hilbre Island, and at George’s Pier, afforded a complete series of points 
identical with those of the later dates of 1893 and of 1903. 
The tides selected for comparison were the equinoctial springs and 
neaps, of the vernal equinox, in the years just indicated, and the records 
were those of the gauges at Hilbre (the Bar), George’s Pier, Eastham 
(Manchester Ship Canal entrance), Garston, Stanlaw Point, Widnes, 
Fidlers Ferry, and Warrington. These gauges embrace the entire tidal 
establishment of the River Mersey. 
The tidal curves, at each particular gauge, showed that no material 
change had occurred, during the thirty years so compared, either in the 
range of the tide or in the form of the curve. However, in the extreme 
upper reaches of the narrow fluvial portion, the tidal stream set in earlier 
