Above and under water
The drawings by the Sienese engineers illustrate devices that would enable persons to build long-lasting structures in water and to construct safe boats. There are countless images of prototypes of diving suits with amusingly shaped masks and visors, as well as human figures kept afloat by inflated leather bags.
Special attention is devoted to measuring heights and distances by means of geometrical instruments and methods. Taccola concentrated on hydraulic applications, while Francesco illustrated numerous devices reflecting the architect's varied requirements.
Taccola and Francesco were keenly interested in "surprise" fountains, i.e., capable of surprising the observer by their effects. These devices had been analyzed by Hero of Alexandria and by Philo of Byzantium in his Pneumatics.
An unusually striking example is the fine drawing of a "surprise" table fountain in the shape of a barmaid.
Taccola's systems, intended to solve everyday problems, rarely show significant technical complexity. By contrast, Francesco di Giorgio compiled an exhaustive classification of pumps, giving detailed notes of their specifications and performance.
The dam on the Bruna River
In 1468, the Sienese Republic launched a project to set up an artificial lake in the Maremma region by building a dam on the Bruna River near Grosseto. The dam was intended to create a fish-stock lake. The project incorporated research of the Sienese engineers on dams and underwater foundations.
In December 1492 the dam collapsed, inflicting many casualties.
In the first half of the sixteenth century, the eminent Sienese architect Baldassarre Peruzzi developed several projects to rebuild the dam, but they never left the drawing-board.