...and it is related to my screen name.

This thing is a demonstration model used to teach people how a steam engine works. It was built by the L.E. Knott Apparatus Company, who supplied various laboratory and teaching tools... all kinds of cool stuff.

Of course, I’m well aware of how a steam engine works, but this demo model was cool, old and affordable... the perfect trifecta. I think it will look nice on my office desk.

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There are visual representations of the piston and slide valve, which move back and forth as the wheel is rotated:

The model features working Stephenson Valve Gear to show how the engine is reversed by changing the timing of the slide valve, using the Johnson Bar:

Here is a section of a page from a 1921 L.E. Knott catalog showing the model on the right (No. 69-30) plus a description and price below:

$6.00 in 1921... according to the internet (it has to be true...) that would equate to about $75 in 2017 dollars. For such a small thing, it was a bit pricey back in 1921. I’m thinking the 20 bucks I paid was a bargain!