Pulleys and toothed wheels raising weights (f. 79v)
With a memorandum to consult Witelo's book at San Marco.
Folio 79v is dominated by a column of mechanism sketches in its upper right: paired weights hung from horizontal bars run down to drums and pulleys, then to rack-and-pinion arrangements where toothed wheels engage straight racks, and finally to single pulleys carrying loads. The surrounding text is sparse. A single memorandum at the top records "Witelo, in San Marco" - a reminder to consult the medieval optical writer's treatise held in that library - and a note beside the sixth figure remarks that one figure suffices in each position.
On this page
Pulleys, drums, and rack-and-pinion raising weights
A vertical sequence of mechanism studies climbs the right margin. Weights hang from horizontal bars over drums and pulleys, then act on toothed wheels meshing with straight racks, and lower down on simple single pulleys. The drawings compare ways of lifting or resisting a hung load.
Memorandum: Witelo's book at San Marco
A brief jotting records "Witelo, in San Marco" - a reminder to look up the treatise of the thirteenth-century writer on optics kept in that convent library. It is a working note rather than a statement of theory. The reference names an author and a place only.
Note on the set of eight figures
Alongside the sixth of the drawn figures Leonardo notes that here a single figure suffices in each position. The remark treats the mechanism sketches as a comparative series. It flags that the eight figures need not be repeated for each case.