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Servicing an 1801 Steam Engine

In our High Mill, we are delighted to have on display the magnificent Boulton and Watt steam engine dating back to 1801; on loan from Dundee City Council via a partnership with Leisure and Culture Dundee.

In this blog, our Maintenance and Technical Support Officer, Kieran, talks us through the process of servicing this beautiful machine.

The engine in the High Mill at Verdant Works


One of only five examples remaining in the UK, this particular engine was ordered from Boulton and Watt in February of 1801, for use at Douglasfield Bleachworks in Dundee at the cost of £517.00. Writing to the manufacturers in March 1802, William Sandeman (Manager of Douglasfield Bleachworks) noted that the engine “gave perfect satisfaction”.

In 2019, the engine was recognised with the Institution of Mechanical Engineers’ prestigious Engineering Heritage Award, for being the only surviving example of a Boulton and Watt engine that had worked in Scotland. Further, the machine’s current proximity to its original setting on the outskirts of Dundee on the Dighty Burn makes this example truly outstanding.


To start the service, we go to the top floor of our High Mill, to access the main beam of the engine. Luckily, we have a little portable ladder and a harness that allow us into all the areas of the beam that need cared for.

Detail from the top of the engine

After applying oil, we check that all the connecting points are nice and tight, and aren’t running loose. The Boulton & Watt pre-dates the manufacture of standardised nuts and bolts, and so, drifts (or wedges) are used instead to hold pieces together. By gently tapping these with a block of soft wood, we can check that they are all tight and held together where they should be.

Arguably the most intricate components of the engine to clean are the valves and cylinder.

The valves of the Boulton & Watt engine

Accessed by a platform on the middle floor of the engine, tending to the cylinder and valves takes time. An oil gun is used to lubricate two oil points connected to the main beam, before all of the motion work is cleaned with the cloth again, in preparation for oiling. There are around twenty oil points in this area. Once again, we use our soft wood block and hammer to gently tap the drifts and seat them back home.

The third area to tend to is the largest; the flywheel and main bearings. These bearings connect the large flywheel to the electric motor that is now used to run this engine.

Like the rest of the machine, the checks carried out at the flywheel and bearings involve ensuring that all the nuts are tight, oil holes are sufficiently oiled and the drifts are in place, through percussive maintenance; particularly at the point at which the flywheel is attached to the shaft.

At the front of the engine, the gears and cogs attached to the flywheel that operate the governor are cleaned over, oiled and inspected for tightness; any that have come loose are tightened or gently tapped back into place. The main gear bearing is checked and tightened with a spanner.

Flywheel cogs

Finally, the wooden A-frame that holds the engine together is checked and adjusted accordingly, before the engine is set to run.

If you would like to see the engine for yourself and learn more about the only Boulton and Watt engine remaining in Scotland, it is on display in our High Mill and is run as and when we have enough staff. As well as our Boulton and Watt, there are opportunities to view looms, roving machines and more machines associated with jute manufacture running in our immersive Machine Hall.

Watch the Service

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