Happy Birthday Iron Trunk

In terms of canal architecture we are lucky since we live close to both Blisworth tunnel and Stoke Bruerne locks. However, just to our south we also have a fine example of the other main component of canal architecture, the aqueduct.

Cosgove aqueduct, or the Iron Trunk, lies just to the south of our village and this week it celebrates its 200th birthday. There is some confusion over the exact date of the opening, according to Alan Faulkner it is January 22nd but British Waterways state that is January 21st. I was reminded of the anniversary by Brian Dunleavy, who blogs about Wolverton history, following the post about our recent New Year’s Day walk around Cosgrove.

Iron Trunk in January 2009

The Iron Trunk has carried the Grand Union (Grand Junction) over the Great Ouse for 200 years since it replaced an earlier unsatisfactory structure which collapsed in 1808. Originally there was a system of locks that provided a crossing at river-level. The locks were used until 1805 when the first aqueduct, designed by William Jessop, was constructed. The line of the locks is still visible. The first aqueduct appears not to have been very satisfactory from the start and it collapsed on February 22, 1808. The embankment also had difficulties and part of it collapsed in 1806.

Compared to some other aqueducts the Iron Truck is relatively modest in height (60ft), modest in length (100ft) and is by no means a ground breaking structure. However, it is an impressive structure and it has proved to be very durable only being dewatered for repairs in 1921 and 1986. It was designed by Benjamin Bevan who adopted the construction technique employed by Thomas Telford at Longdon-on Tern where he constructed the world's first large-scale cast iron navigable aqueduct. The iron sections for Cosgrove were cast at the Reynold’s Ketley foundry at Coalbrookdale who had supplied the material for the Longdon aqueduct.

Longdon-on Tern aqueduct in 2006

Telford employed the same technique at the world-famous Pontcysyllte aqueduct.

Pontcysyllte Aqueduct in 2002

British Waterways have just started giving the Iron Trunk a birthday facelift. It appears that this includes a repaint. Recently BW took samples of the 1811 paint by abseiling over the side. Video of this was featured on our local BBC news programme. BW plan to dewater the aqueduct at some stage. It would be great to see this happen, particularly seeing the water drop into the river below.

Iron Trunk dewatered in 1921

If you are interested in canal aqueducts then the blog by Captain Ahab specifically about aqueducts is very useful. Brian Dunleavy's blog about the Iron Trunk has some intersting images and details of the history. There is also a Wikipedia page on the Cosgrove Aqueduct.

I have earlier posts about the Iron Trunk and my visit to the Longdon-on-Tern Aqueduct.

The history of the Iron Trunk is also well described in Alan H Faulkner’s 1972 book “The Grand Junction” which was published by David & Charles. It provides a great description from the Northampton Mercury of the aftermath of the collapse of the first aqueduct.