Monday Photo

Living Together

Tree at Goosey Bridge  Olney

The Monday Photo

Remember the tree I showed you not too long ago, that wasn’t actually one tree but several things growing together? I’ve found another example, this time in Olney.

I’d gone for a walk with my nephew a few days before Christmas, and we crossed Goosey bridge (you can see it in the background) and around the edge of Goosey Island, on the Great Ouse. As we left the island I spotted this one on the bank. I couldn’t get too close, but I could see there’s a compact shape that’s still in leaf, while another set of branches, this time bare, has grown out further.

This tree or trees (I’m struggling to find a word that clearly describes it) is very much the same shape as the one I found in Woughton on the Green, except that the branches come down to a lower level. Perhaps only sheep are kept in this field, not cattle, and as sheep can’t reach as high to nibble at those tender shoots, the branches can survive closer to the ground.

If you’ve seen other examples of this mutual growing arrangement, please let me know in the comments.

 

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It’s Quicker Via (this) Canal

Soulbury bottom lock 24

The Monday Photo

In 1805, it became far more practical to bring goods to London from the factories in the North and the Midlands when the Grand Junction Canal was opened; we know it as the Grand Union Canal, and this is Three Locks, not far South of Milton Keynes.

Before that year, the only way to London by water was via the Oxford canal, joining the Thames at Oxford then going downstream to the capital; it was much further and depended on how the Thames was running. These routes both still exist.

But how much quicker was it when the new route opened? On the older route via the Thames it’s 172 miles each way and and modern estimates reckon it will take you 151 hours of travelling to go there and back.

For the same starting and finishing points but via the Grand Junction Canal it’s just 101 miles each way, and the modern estimate is 102 hours for the round trip. So the new route cut a third off the return journey time and was more reliable, since none of it was on the river.

The new canal did well, but competition from the railways from around 1840 meant the canal struggled to survive, though it continued to take commercial traffic right up until the 1950s, one of the last canals to do so. Now it is mostly used by leisure craft and people who live on boats, and has now been open to traffic for 215 years.

The photo shows the bottom lock of the three, which together raise or lower boats just over twenty feet, and the end of the Greensand ridge.

I don’t know what sort of speed the 18th Century horse drawn boats could average, does anyone know? I suspect they’d be slower than a modern boat with an engine. But the time advantage of the new route is obvious.

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The Christmas Post

Christmas Postie

The Monday Photo

This is my postie, wearing his reindeer hat. I have no idea what his name is, but it's a fine hat. Keeps the ears warm, too; stylish yet practical.

That’s all folks.

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This is Not a Tree

This is not a treeThis isn't what it appears to be.

The Monday Photo

This is not a tree. It looks like a tree, but when I went to look at it again at the weekend I found three sorts of leaves and two main trunks. It hasn’t been snowing in the Ouzel Valley Park; this photo is from a previous year but you can still see the two main trunks.

I walked around and around it on Sunday trying to work out just what is growing here, and here’s what I think. The biggest trunk is Hawthorn. It has been strangled by ivy and it’s struggling. I found just one Hawthorn leaf and a few red berries which gave me a clue; there were very few thorns.

Most of the Hawthorn branches I could see were the lowest ones here. Even though it grows leaves and is obviously alive, the main trunk is rotten in places.

The Ivy stays close to the crown of the Hawthorn and its evergreen leaves are in shadow, just where they like to be. Considering how thoroughly the Ivy has strangled the Hawthorn, there are surprisingly few of them.

The other tree is probably a Dogwood, and it’s doing quite well. Even now in December, it still has many of its leaves. In the past one of the branches has touched the Hawthorn’s trunk and they have joined together; the Dogwood bending away like a bent elbow above the join.

The curious flat bottomed shape to the foliage we can see here is down to livestock, who might eat the tender leaves and who certainly like to rub up against the trunks, judging by the muddy and hoof marked ground I found underneath. The dense foliage will give shelter to livestock in the height of summer and the two trees and the Ivy all provide food for many insects and birds.

What was the other thing; why am I showing you a photo taken in the snow? Oh yes. of course.

I wish you all a merry Christmas. and a happy and healthy New Year.

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How Do Arches Work?

Norman arches  StewkleyThe two nearest arches support the weight of the tower. There's another arch over the window, and above it you can just see the ribs of the roof, which is in the form of two intersecting barrel vaults. A barrel vault is a long arch, like the tunnel at Gayhurst in last week's Monday photo. This is the Norman church at Stewkley.

The Monday Photo

I see a lot of arches travelling round for the North Bucks Wanderer. The last five posts have all had something to do with arches, even if you couldn’t see them in the photos.

So how do they work, and why don’t they fall down, even if they are hundreds of years old? It’s all due to the way stone, or brick, is strong.

Stone and brick are enormously strong in compression; when they are being squeezed. Arches take advantage of this, by directing the load or weight of whatever is above the arch sideways.

This is how it works. The bricks or stones around the arch are wedged shaped. The weight above them makes each wedge shape (they are called Voussoirs) try to drive itself deeper between its neighbours.

They all squeeze each other and the weight is directed around the arch and into the abutments on each side.

How arches work2

As long as the abutments (see the diagram) are strong enough to resist the weight, the arch doesn’t have to be a complete semi-circle, and some arches are very shallow indeed. This is very handy for things like railway bridges; a train won’t get over a hump backed bridge.

The red arrows show the direction of the forces involved. And yes, they do show the abutments pushing back at the arch. They have to, weird as it may sound, or they would be crushed. With arches like the ones in the photo, there are more voussoirs and they just direct the forces (the thrust lines) vertically down.

The Voussoir at the crown of the arch is sometimes bigger than the rest and called the keystone. That’s just for decoration; it’s no more important than any of the others.

Arches are very stable. Even if the foundations shift, it is likely the arch will stay up. With a simple wall, if the thrust lines stray outside the wall, it will hinge or crack around that spot and fall down. The wedge shape of the voussoirs in an arch means they will just settle into a different position.

You need at least four hinge points before an arch will fall down. You can see cracks above the big arches in the photo. Arches are great for spanning large gaps. That’s unlike stone slabs, which will just crack and fall if the gap is too big.

The first known arches were in Egypt and Mesopotamia, 5,600 years ago and were made of brick. Stone ones came later.

If you want to see a wide selection of arches here on the North Bucks Wanderer, look for churches or bridges in the categories in the sidebar.

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Tunnel Estate

Gayhurst tunnel

The Monday Photo

Most people don’t realise when they drive through Gayhurst, but there’s a tunnel hidden under the road. Built before 1793, it gave foot access to part of the grounds of Gayhurst House, on the other side of what’s now the B526.

Through the tunnel there was a Chalybeate (heavy iron content) spring, and a bath house which I think is much enlarged now. Chalybeate springs were once thought to have health-giving properties.

The spring is still there but the two boat houses on the Great Ouse are, I’m told, now gone. The bath house sat in open parkland, but the spring and boat houses sat inside Gayhurst Spinney.

The tunnel runs under a causeway, built to raise the 1709 turnpike above flood water. We don’t know if the causeway came first, or if it and the tunnel were built at the same time. This tunnel is just a quarter of a mile away from one of the biggest walnut trees in the United Kingdom.

The only other tunnel I can think of in North Bucks is under the canal aquaduct at Old Wolverton; also close to the Great Ouse. That’s it, unless you know better.

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