The records during a storm on October 29, 1838, gave an
entirely different result, as the time was retarded only ten or
twelve minutes, but the height was increased by 8 ft On another
occasion the tide at Liverpool was increased 7 ft by a gale.
The Bristol Channel holds the record for the greatest tide
experienced around the shores of Great Britain, which occurred
at Chepstow in 1883, and had a rise of 48 ft 6 in The
configuration of the Bristol Channel is, of course, conducive
to large tides, but abnormally high tides do not generally
occur on our shores more frequently than perhaps once in ten
years, the last one occurring in the early part of 1904,
although there may foe many extra high ones during this period
of ten years from on-shore gales. Where tides approach a place
from different directions there may be an interval between the
times of arrival, which results in there being two periods of
high and low water, as at Southampton, where the tides approach
from each side of the Isle of Wight.

The hour at which high water occurs at any place on the coast
at the time of new or full moon is known as the establishment
of that place, and when this, together with the height to which
the tide rises above low water is ascertained by actual
observation, it is possible with the aid of the nautical
almanack to make calculations which will foretell the time and
height of the daily tides at that place for all future time. By
means of a tide-predicting machine, invented by Lord Kelvin,
the tides for a whole year can be calculated in from three to
four hours. This machine is fully described in the Minutes of
Proceedings, Inst.C.E., Vol. LXV. The age of the tide at any