A dog's life

Dog-powered engines seem not a little far-fetched but at Proceedings of the Athanasius Kircher Society there are two or three wonderful images: dogs, or, evidently, sheep were used for a variety of purposes: to power sewing machines, butter churns, et cetera.  Turnspits took their name from their work.

(The site last linked to includes the amusing anecdotes of a bishop of Gloucester's sermon on 'Ezekiel saw the wheel' and the turnspits' regard for laborers' rights.)