Turning the hand-crank sets in motion the gears and linkages that operates the wings, legs and arms of the pilot. It's a pretty big model, measuring 17" by 24" by 12". The wooden construction kit uses a pegged gear train -- a lantern pinion and contrate pin wheel. This component alone would make this a model worth examing closely!
Here is where you can get the wooden ornithopter model.
Leonardo's Machines: Da Vinci's Inventions Revealed
From Leonardo da Vinci's descriptions and drawings - and by using digital imaging - armoured ships, hydraulic machinery, winches and machines destined for use in war, work and pleasure emerge fully equipped and functional in stunning 3-dimensional, computer-generated artworks. A fascinating in-depth discussion of da Vinci's work and inventions accompanies these illustrations, revealing at the same time the incredible journey the authors of this book travelled whilst compiling it.
Here's is where you can find books on Leonardo's inventions.