Thursday 19 March 2015

Alliterative leisure: Luxulyan, leats and launders

A just-over 6 mile walk with one of our groups took us to the Luxulyan Valley further west in Cornwall, near St Blazey. We've passed by many times but have never taken the short detour off the main road and walked the area. What a little gem! On the face of it, just a wooded valley but one with a long history of industrial development. What's there now to be seen is mainly down to the efforts and vision of one man, Joseph Treffry.  His interest in the valley began when he needed to find a way of getting the ore from a mine he owned onto ships at Par Harbour, which he had built. His answer was to link the harbour to a canal at the bottom of an inclined plane he had constructed. The inclined plane was operated by a large water wheel and this needed a supply of, mmm, guess what?, water. This, coupled with the need of the same (lots of it) for nearby mines, quarries and clay-pits, lead to the development of a complex system of leats and launders, culminating in the construction of the unique dual purpose Treffry Viaduct. And all of this started around 1820. My sort of walk - lots of industrial archaeology, out in the open air and good (but not intrusive) company.
For those who like to know the location, here's a map of our walk. Basically it was up one side of the valley to Luxulyan village and then back down the other side to our starting point. The profile shows this quite nicely but doesn't show the mud or give the sound of rushing water that was ever present.
The bottom of the inclined plane, showing the granite blocks upon which the rails were bolted. Unusually, many of the 'shoes' for the rails were still in place. At 1 in 7 it's quite a steep gradient and rises about 400 ft over just under a mile.
Water and greenery wherever we went.
Here we are looking down on the Fowey Consols Leat, one of the earliest of Treffry's engineering projects. It runs for about three miles in total and was built to carry water to Treffry's Fowey Consols copper mine. The original course of the leat ran more middle right than bottom right, the tree marks its old route. It now disappears into a tunnel, built in the 1940's, but before that it went around a rocky outcrop in a cantilevered wooden launder. It must have been an impressive sight and an equally impressive feat of engineering.
Lots of rather misshapen sessile oak trees all along the valley walk, probably due to their growing towards the light (positive phototropism to the botanists amongst us).
And this is the water chute that feeds the power source that hauled wagons up the incline, the Carmears Wheel. Ah, it must be overshot, I hear you say?  And you would be right. The water comes via the Carmears Leat which, in part, is carried across the valley by the Treffry Viaduct. Once it had driven the wheel, the water drained into the Fowey Consols Leat and was subsequently used elsewhere. Obviously, the water is not running at the moment due to essential repair work on the Viaduct.
The original wheel was some 30 foot in diameter and , through a series of cogs in a nearby winding shed, the motion of the wheel was transferred to haul the wagons.  What remains is the central shaft of a later wheel, around 40 foot in diameter, that was later used to power a china stone grinding mill.
Looking a little like a discarded bicycle, the cogs and wheels for the grinding mill can still be seen next to the wheelpit, which is to the left. The powder produced by the grinding mill was mixed with water to produce a slurry and this was piped down the hill, by gravity, to be further processed by settling and drying. This part was in operation until the early 1960s.
When Joseph Treffry started his enterprises, he faced a pretty basic problem: his mine, quarries and water sources were on one side of the very steep valley and where he wanted his water wheel and the incline to be was on the other side of the valley. I like to think he put on his top hat, rubbed his chin, kicked his cat and then said "I'll build a bridge. Wait a minute, I can do better than that..!". And he did, he came up with a dual purpose structure - a combined viaduct and aquaduct. The viaduct carried the horse-drawn tramway delivering the ore/clay to the top of the incline and the aquaduct, situated directly under the granite slabs of the tramway, carried the water of the Carmears Leat to the water wheel. At each end of the retaining balustrade there are curved walls ending in an elegant pillar, adding to a structure that is aesthetically pleasing as well as functional.
The viaduct from below. Each granite block was quarried and shaped locally. From a distance it blends into the landscape from whence it came. Close up the skill of the craftsmen is obvious.
It's still a little early for many flowers. There were a few primroses, celandines and wood anemones but lots of this Spring Euphorbia. And, yes, I do know that most of the colour comes from the lime green bracts rather than the actual flower.
 

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