For many years, folio 812r of the Codex Atlanticus was considered as Leonardo’s famous “automobile” project. Only recently has it revealed its true nature as a cart devised for use in theatrical settings.

The manuscript page shows two distinct projects, a provisional and preparatory drawing, and a more well-defined one at the centre of the folio. Two large spiral springs underneath the horizontal cogwheels of the cart provide the motive power and set the wheels in motion; they also act as a lever system for theatre puppets. An additional ingenious device serves as a remote control handbrake.

The dimensions of the machine are smaller than an automobile, probably one metre by one metre and no more than one metre high. However, the cart can be considered as one of the first automated mobile devices in history.

There have been many inaccurate reconstructions of this machine which served to do little more than raise doubts as to the real functioning of the cart. In 2004 a functioning model was built by the Istituto di Storia della Scienza, Florence, and Leonardo3, Milan, though inevitably there are aspects of the design that remain speculative.