Uploaded August 2026 | Updated September 2026, 1 week ago
It's just a pipe sticking out of the ground in a forest. But I think it's fascinating.
This particular pipe is on the Pegsdon Hills in the Chilterns, almost at the highest point of a large underground water main. And that raises a rather obvious question:
Why would anyone build a water pipe over the top of a hill?
The answer involves trapped air, water pressure, gravity — and something that could potentially cause a very large pipe to collapse.
The pipe can actually do two things: it can let air out of the water system, and it can also let air in.
So, for the purposes of this video, I've decided to call it a "Burping and Gulping Pipe."
But that's not the only interesting thing going on here.
The whole system leads to a much bigger question: Can gravity actually make something go upwards? We normally think of gravity as making things fall down. But when we understand water pressure and buoyancy, things become a little more interesting.
I'll also take a brief detour into the history of nearby Telegraph Hill and the ingenious optical telegraph system used during the Napoleonic Wars.
Because, as I always say… There is always something interesting to see.
It's just a pipe sticking out of the ground in a forest. But I think it's fascinating.
This particular pipe is on the Pegsdon Hills in the Chilterns, almost at the highest point of a large underground water main. And that raises a rather obvious question:
Why would anyone build a water pipe over the top of a hill?
The answer involves trapped air, water pressure, gravity — and something that could potentially cause a very large pipe to collapse.
The pipe can actually do two things: it can let air out of the water system, and it can also let air in.
So, for the purposes of this video, I've decided to call it a "Burping and Gulping Pipe."
But that's not the only interesting thing going on here.
The whole system leads to a much bigger question: Can gravity actually make something go upwards? We normally think of gravity as making things fall down. But when we understand water pressure and buoyancy, things become a little more interesting.
I'll also take a brief detour into the history of nearby Telegraph Hill and the ingenious optical telegraph system used during the Napoleonic Wars.
Because, as I always say… There is always something interesting to see.
