We came through Harecastle Tunnel this morning, and in the course of the subterranean trip I got musing… I wonder how many bricks were used to line the bore?
So I did some rough calculations. They had to be rough, the height varies considerable, as does the width, and I had to make an assumption about the underwater profile. But this is what I reckon the average shape is…
Because it’s only going to be an estimation, I took the bore to be circular and added a bit, giving me 40’ or 160 brick courses.
The length of the tunnel is 2926 yards, or 8778 feet, which will need around 11,700 bricks laid end to end. A simple multiplication gives the staggering number of around 1¾ million bricks! That's a single brick thickness. I think we can safely assume that the walls will be at least 2 bricks thick. That’s a lot of bricks.
A dry brick weighs in at around 10lb, so 3½ million bricks would be around 15,500 tons.
A massive logistical operation!
Notice I’ve used imperial measurements, it seemed appropriate, somehow..
Anyway, back to cruising. We were up early-ish, and Meg’s morning walk revealed all three locks above us empty with the bottom gates standing open. An opportunity too good to miss! We set off about 09:00, spent 20 minutes at the services filling and emptying, then took advantage of another boater’s idleness.
Up Red Bull Lock, grass cutters at work in the pub garden, Meg having a good old scratch.
Mags heading for Pooles Locks, taken from under the aqueduct carrying the Hardings Wood Branch to the Macclesfield Canal.
There was a lot of water in the last pound, decreasing the headroom under the already low bridges below the summit lock. We had a look at the lower, left side…
But decided that the slightly higher one on the right was a better option!
That’s it, the top of the Cheshire Locks, or Heartbreak Hill as the boatmen used to call it. Mind you, they’d do them in a morning.
Lock 41, the Canal Tavern in the background
Now we’re back to that tunnel…
We pulled in on the moorings to wait for a convoy of three boats coming north. Tunnel traffic is controlled by keepers at either end, booking boats in and out.
Looking down at the tunnel entrance(s).
The first boat of the northbound convoy is just emerging.
Beyond the current portal can be seen the entrance to the original 1777 tunnel, which closed in 1914. The one we use now was built in 1827 by Thomas Telford, and both carried one-way traffic till the closure of the earlier Brindley-built bore due to subsidence and a partial collapse.
Brindley’s early tunnel
Our turn now, at 10:25
If you’re quick with the camera you might see Kit Crewbucket…
Some odd rust stained flowstone sculptures near the middle of the tunnel.
We popped back out into the bright sunlight after 36 minutes, not a bad time through the tunnel.
If we’d have carried on yesterday through the rain we’d have stopped at Westport Lake, where good moorings give access to pleasant walks around the lake.
Westport Lake moorings, unusually empty.
But it was too early today to stop here, so we pushed on to Etruria.
Bottle kiln at Longport
Busy, busy at Longport Wharf
We had an uneventful trip to Etruria, Mags spent some time on the tiller while I went in to make a brew and make a start on dinner.
Approaching Etruria and the junction with the Caldon Canal
The chimney is at Jesse Shirley’s Flint and Bone Mill. Well worth a look if it’s open when you’re passing. I did, earlier in the year.
Instead of mooring on the Trent and Mersey above Etruria Lock, where you’re likely to be run down by whizzing cyclists at knocking-off time, we’ve taken to turning onto the Caldon, winding and mooring below the staircase locks. It’s a lot more pleasant here, with a large green area for Meg.
On the Caldon for the night
Down Stoke Locks tomorrow to Barlaston. Deep joy…
Locks 3, miles 6½