Leonardo on hydrostatic force: a research engineering approach towards the idea of hydrostatic pressure?

As evidenced by many scholars, hydraulics was one of the main interests of Leonardo da Vinci; his manuscripts are full of drawings and projects on water, accompanied by a variety of notes, subtle meditations, and some remarkable considerations. Leonardo's expertise in this field surely comes, first of all, from the well-established technical tradition of his time. But the particular approach that he often adopts to study and solve the problems encountered in his activity as an engineer sometimes led him to revise or innovate some aspects of this tradition. This approach, that today reminds us the methods of research engineering, is effectively resumed by Hunter Rouse in his volume 'Engineering Hydraulics': “Practically every problem in engineering hydraulics involves the prediction by either analytical or experimental methods of one or more characteristics of flow. There are, in brief, three different bases for such prediction. The first is that of "engineering experience" gained in the field by each individual engineer. The second is the laboratory method of studying each specific problem by means of scale models. The third is the process of theoretical analysis. The most effective solution of almost any problem will be obtained by combining the best features of all three methods of approach.” Examples of this kind of method are given by Leonardo's personal experiences, laboratory studies and theoretical analyses on hydrostatics (especially on pressure and buoyancy) that were stimulated by the necessity of solving specific problems in the field of navigation or in the construction of canals, banks, reservoirs and scales