Brixton Windmill is 15 metres (nearly 50 feet) high.  It might look tall, but it’s pretty modest when you compare it to England’s tallest tower mill at Moulton in Lincolnshire, which is twice the size!  The walls are made of yellow London brick, coated in black tar to protect them from the weather.

Brixton Windmill is a tower mill – only the top part of the building turns to catch the wind. This was a better design than earlier post mills, where the whole body of the mill with all its machinery had to turn into the wind – which took more effort and the mills weren’t as sturdy.

Our mill has four sails (the ‘arms’ you see that turn in the wind).  On other mills people have experimented with more sails to catch more wind  – some have six or even eight.

The cap is the very top part of the windmill and it’s the only part of the mill that turns – so that the sails can face into the direction of the wind as it changes.

It looks a bit like an upside-down boat.  It’s made of a timber frame and the wood is coated to weather the wind and rain.

The cap can be turned using a chain: you can see the wheel the chain turns at the back of the cap.

The sails are the ‘arms’ that turn in the wind – although south of the River Thames sails were traditionally called sweeps.

There was probably a wooden platform one floor up running round the outside of our mill, so the miller could reach the sails.

The original sails on Brixton Windmill were removed and burnt in 1864 when the mill fell out of use. We’ve restored the sails based on old photographs of Ashby’s Mill which show two different pairs of sails – common sails and patent sails, we have both.

The common sail was the standard kind of sail in the 18th century and looked a bit like a garden trellis with criss-crossing wood. Canvas sailcloth was stretched along each sail frame. In light winds the whole canvas would be unfurled, in stronger winds the sails would be ‘reefed’ (rolled back) so that only part of the surface was exposed so the sails didn’t turn too fast.

The common sail was light, simple, cheap and fairly efficient, so it continued to be used well into the 20th century. But to adjust them when the wind changed, you had to stop and manually adjust each sail one at a time when it was at the bottom of a turn – so it took a while to adjust all four.

In 1807 a man called William Cubitt invented patent sails, which are more expensive but much easier to adjust. Patent sails are made up of shutters that can be opened and closed on the same principle – like a Venetian blind. This design meant you could automatically change the amount of sail exposed to the wind as the strength of the wind varied, saving time so you could produce more flour.

Here’s an extract from an advertisement of Cubitt’s patent in the Norfolk Chronicle on 13 June 1807:

“CUBITT’s new invented SAILS or VANES for WINDMILLS will preserve an even and uniform velocity in the most unsteady wind and will clothe and unclothe themselves by the wind’s impulse (without altering their angle of weather) whether they be in motion or at rest; by which means they are rendered perfectly safe in any gale of wind, however sudden and strong it may be. These vanes will be found to be a very valuable acquisition to every one whose interest consists in having their Mills make the most possible of weak winds and never exceed a proper velocity in the strongest; they are easily applicable either to Post or Tower Mills, are very simple and durable in their construction and not in the least liable to be out of order. They will be found extremely useful in draining of marshes as they may be left to work night and day, perfectly safe without any person attending them.”