Kew Bridge Steam museum

This is a great place - originally a water pumping station and now full of working steam engines of all shapes and sizes. I just love steam engines working, big shiny works of art.
There was a whole commune of little engines all linked up with belt drives -helping each other along as it were; a couple of big rotative engines (like the big red one in the science museum) going round and round and some twins and triples.
But it was the beam engines (or Cornish engines we discovered they're called) that really blew my mind. Two giant engines side by side in a hall going up three floors, one was in steam and you could climb up the stairs and catwalk to be level with the beam. It was quite scary watching it go up and down just a few inches from your face. I always expect them to thump or vibrate but everything just smooth and strong, up and down, massive.
Then we followed a sign saying 'to the 90" ' . 90"? That doesn't sound very big - that's less than 3m. We found ourselves in a brick building the size and height (and style) of an average anglican church, aisles and support pillars rising into the ceiling 3 floors up, some sort of large round tank.....but no sign of the engine...where was the 90"?
Then I looked up. This engine was so big we hadn't even noticed it. We were standing right under it. Like standing under a dinosaur - oh what interesting tree trunks....why are they moving?.....oh! - The 90" isn't the length of the beam - it's the diameter of the cylinder, the beam is so big it would just about fit in the length of our garden.
In the next aisle of the church was an even bigger one (the 100"). The 90" was due to come into steam at 3pm (virtually everything else has to shut off for it to get enough steam and also it takes all day to build up pressure!) but the 100" is still being restored. I'd have loved to stay and see this giant beast in action but it would have meant waiting around and we had to go onto granma's. Really want to go back one day though.
www.kbsm.org