Fynnon Leinw, Cilcain ('Tidal' Well)

[BS3]

One of my favourite small 'local' marvels is the ebbing and flowing well at Cilcain in my native northeast Wales. It was first mentioned in 1188:

There is a spring not far from Rhuddlan, in the province of Tegeingl, which not only regularly ebbs and flows like the sea, twice in twenty-four hours, but at other times frequently rises and falls both by night and day

Even better it's still there, and still (despite a general fall in the water table due to mine drainage) just about ebbs and flows.

There is a very detailed survey of historical sources here. And the Blue Bell pub in Halkyn is very good if you're passing.

Thanks to limestone geology the whole area is full of hydrological wonders including the "bottomless" Powell's Lode Cavern and St Winifride's Well, most of which connects together in some (largely unknown) way.

 

[RaM]

There's one near Settle that was still working last time I looked, it by all
accounts as been investigated to see how it works a time or two but they
came up with no answers and the well as not worked quite as it did
since, I have seen it ebb and flow and think it's to do with syphoning
the level drops and refills quite quickly when it does.
I have been to St Winifride's Well, a few years back it was a way point
on a rally but it was closed to the public at the time so did not get to
see it close up.

https://thejournalofantiquities.com...and-flowing-well-giggleswick-north-yorkshire/

1651050203902.png

 

[SimonBurchell]

I few interesting links:

Tide in Wells by Paul Schureman, from JSTOR but open access. Introductory blub:

Tidal phenomena at inland boreholes near Cradock by Andrew Young, from Edinburgh Research Archive. First couple of paragraphs, but more are available via the link:

Observations begun in 1905 and carried on at intervals until the present year on a group of wells on a farm at Tarka Bridge, Cradock District, are described in detail.

The wells have not been bored very deep, the deepest being 225 feet, but it is obvious that the bores connect with deeply extending fissures, as the waters issue at temperatures of about 80° accompanied by large quantities of natural inflammable gas (methane), while sulphuretted hydrogen is present in notable quantities in solution in the water. The wells are 2,700 feet above sea-level and over 100 miles from the coast.

Measurements of the pressure at which the water issues show a remarkable fluctuation, in some respects analogous to the tidal fluctuations of the sea.

A series of direct measurements covering several days established the fact that there was a real fluctuation both in the amount of water discharged and in the well- pressure. Continuous records were then obtained over longer periods by means of clock -driven, self -recording apparatus in order to study the precise nature of the fluctuations. The longest continuous record obtained extends over a. period of fifteen weeks. This graphical record shows that the semi-diurnal fluctuations attain a maximum amplitude at fortnightly intervals at times corresponding to the times of new moon and full moon throughout the fifteen-weeks' period.

 

[BS3]

There's one near Settle that was still working last time I looked, it by all
accounts as been investigated to see how it works a time or two but they
came up with no answers and the well as not worked quite as it did
since, I have seen it ebb and flow and think it's to do with syphoning
the level drops and refills quite quickly when it does.
I have been to St Winifride's Well, a few years back it was a way point
on a rally but it was closed to the public at the time so did not get to
see it close up.

https://thejournalofantiquities.com...and-flowing-well-giggleswick-north-yorkshire/
View attachment 54790


1651050203902.png

It's possible there's some sort of underground syphon - a lot of the 'wells' are actually risings for water filled cave systems. It's also been suggested that a some of these 'ebbing' wells do alter their flow quite dramatically with rainfall, but that the idea of a tide-like ebb and flow was more folkloric - as in the second part of Hulse's article on Fynnon Leinw.

 

[RaM]

The one near Settle if you stand near it you cant see anything other than the well
but if you cross the road and down a lane you come to quite a forceful stream that
seems to come from the direction of the well, my thoughts were that it as been engineered
to give clean drinking water to passers by and their animals, and the ebb and flow
is intended to flush the well regularly to keep the water clean, don't think it is anything
to do with tides as I have seen it cycle several times over a matter of maybe half a hour.