The automated roasting spit is a design which has a perfectly practical application and is quite simple. Leonardo did not actually invent this idea, but he drew illustrations which show he studied its operation and how the draught from different sized fires produced a varying result during the roasting of the meat. A hot fire has a stronger draught and so a roast browns more evenly. Leonardo noted that:
"the roast will turn slow or fast depending on whether the fire is small and strong."
Leonardo's lifting jack is not that dissimilar from the jacks used with modern vehicles. Made up of reducing gears, a rack and a a crank handle, it would have been of a great deal of use in Leonardo's day. We do not know if this was an invention by Leonardo, a modification of a piece of equipment, or simply a detailed sketch of equipment already in general use.
Leonardo's textile machines are among his lesser-known pieces, however he showed great foresight in this area and designed clipping machines, automatic spindles, shearing machines and two rope-twisting machines which appear in Codex Atlanticus. The more complicated of these spins and twists fifteen strands simultaneously.
interest is his fabric stretcher which made it possible to achieve
a nearly industrial output when several machines were used together.
The fabric was stretched on a wooden frame and then automatically
cut with two gigantic shears. This design was to reappear in
England during the eighteenth century. At this time it caused
grave problems as it replaced so many workers large numbers