Didascalia: Manuscript E, folio 75 v.

The entire folio is dedicated to the lagoon dredge, called "strumento per cavare terra" (instrument for digging earth). Leonardo associates the letters bf-mn to the machine, to indicate the parts and mechanisms that are of most importance for its operation (b = arms; f = gearwheel; m = pile; n = wheel arm; mf and mb = ropes). Two annotations follow. A short one, on the right-hand margin, stating that "Il polo ha comodità del potere discendere in tanta bassezza, quando debba discendere la rota per profondare l'acqua al palude" (the pile may go down as deep as the wheel need to go down to reach the mud below the water). The second annotation is written in the centre of the page and is much longer. It describes the advantages of the lagoon dredge, along with the main phases of its operation and the operating system itself.