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The delay, between the moment of New or Full Moon (or syzygy, a favourite
word of mine) and the greatest range of tide near to it (spring tide), has
had the name for many years "the age of the tide". Not a perfect name,
perhaps, but if Frank Reed and Trevor Kenchington had both used it
consistently, much misunderstanding would have been avoided.

Frank said-

>This all got started because I
>pointed out that Bowditch wrote in early editions about Spring Tides
>occurring three days AFTER New Moon/Full Moon. That rule applies
>reasonably well in
>parts of northwest Europe.

I don't doubt that Bowditch made such a statement, though I don't have an
early Bowditch to check. But on what basis does Frank justify his own
claim, that Bowditch's three-day rule "applies reasonably well in parts of
northwest Europe".  My own experience supports the statement in the
Admiralty Manual of Tides "The average value of the age is about 1 to 1 1/2
days", perhaps in some parts of Europe 2 days. I think that Cassini, who I
quoted in an earlier mailing, got the age of the tide about right, at 1 day
to the West of the English Channel, 2 days to the East.

In an earlier mailing, Frank had said-

>Northwest Europe has a
>SPECIFIC phase lag that Bowditch copied from European sources (or maybe simply
>"knew" from the common culture of European sea lore). The specific phase
>lag for
>Europe leads to a specific lag of the Spring Tides there. That phase
>difference applies to much of northwest Europe, but it does not apply to
>the Americas
>generally.

We know now that the phase-lag or phase difference Frank was referring to
was the age of the tide. Now he is back-tracking somewhat by claiming only
that "That rule applies reasonably well in parts of northwest Europe."

Well, I simply ask Frank to supply some evidence to support his own claims
about that three-day "age", on which he has built such a big argument. To
which parts of northwest Europe does he claim that it applies? I am not
claiming he is wrong; just asking for the evidence.

George.

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contact George Huxtable by email at george@huxtable.u-net.com, by phone at
01865 820222 (from outside UK, +44 1865 820222), or by mail at 1 Sandy
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