228 
MR. ROBERT GURNEY ON THE TIDES OF 
calm in the night, and the wind rose somewhat and blew from 
the East about io a.m. The tendency of Easterly winds is 
to increase range, but it seems unlikely that wind of the force 
observed should have had so immediate an effect. 
The average range for the four days was 8.19 in., and the 
average duration of rise and fall was 6 h. 6 m. and 6 h. 13 m. 
respectively. The duration of the rise in the morning of 
September 14th alluded to above was 7 h. xo m., which is, 
of course, exceptional. 
High water was found to occur on an average 2 h. 16 m. 
after high water at Yarmouth Pier. 
Acle Bridge. 
At Acle Bridge, about 12 miles from Yarmouth, tide charts 
have been taken for the week July 4th — nth, 1906. The 
weather conditions during this time were very favourable ; 
no rain fell and the wind was light and variable. The moon 
was full on July 6th. 
From this series of charts the tides have been transferred 
in a diagrammatic form to Fig. 5 and there compared with 
the tides at Yarmouth Pier. It will be seen that they follow 
the latter exactly, and that both increase with remarkable 
regularity till the day after full moon without any pronounced 
diurnal inequality. From that point diurnal inequality 
becomes very pronounced, but, while the smaller morning 
tides regularly decrease, the larger afternoon tides remain 
at spring height at Acle and only very slightly decrease at 
Yarmouth. 
The range at Acle during the period varied from 9.2 in. 
to 14.8 in., showing an apparent loss of height of about an 
inch in the two miles from Muckfleet. During the first day 
(July 4th — 5th) simultaneous observations were made by 
means of a second identical tide gauge placed above the Bridge, 
and these showed a difference in range between the two 
points above and below (barely 100 yards apart) of inches. 
There can be no question of the correctness of this result, and 
the difference is evidently due to the obstruction offered by 
the narrow span of the bridge to the progress of the wave. 
