Bodmer's sliding cylinder engine

The nineteenth century was a time of gloriously barmy variations on steam engine design before, gradually, the forms we know today took precedence.

Patented in 1841 by Johann Bodmer, a Swiss gentleman, this engine works by means of a moving cylinder, reciprocating about a fixed piston rod. Interesting idea, but not one that gained a deal of traction at the time.

None are known to have been built, which probably saved a great deal of damage to the foundations of Victorian engine houses.

Finely made, this engine came to us with a collection of models at the end of last year. Standard of machining is to a high standard, fit and finish good - it turns over freely.

Not at all sure how it's supposed to work - putting air in what looks like the inlet does nothing, putting it in what we assume to be the exhaust underneath causes the cylinder to move, the crankshaft making half a revolution.