420 
THE YAL DI Oil IAN A. 
waters were turned into its present channel, though the prin¬ 
cipal drainage of the Val di Chiana appears to have been in a 
southeastwardly direction until within a comparatively recent 
period. 
In the sixteenth century, the elevation of the bed of the 
valley had become so considerable, that in 1551, at a point 
about ten miles south of the Arno, it was found to be not less 
than one hundred and thirty feet above that river; then fol¬ 
lowed a level of ten miles, and . then a continuous descent to 
the Paglia. Along the level portion of the valley was a boat- 
able channel, and lakes, sometimes a mile or even two miles 
in breadth, had formed at various points farther south. At 
this period, the drainage of the summit level might easily 
have been determined in either direction, and the opposite 
descents of the valley made to culminate at the north or at the 
south end of the level. In the former case, the watershed 
would have been ten miles south of the Arno; in the latter, 
twenty miles, and the division would have been not very 
unequal. 
Various schemes were suggested at this time for drawing 
off the stagnant waters, as well as for the future regular drain¬ 
age of the valley, and small operations for those purposes were 
undertaken with partial success ; but it was feared that the 
discharge of the accumulated waters into the Tiber would pro¬ 
duce a dangerous inundation, while the diversion of the drain¬ 
age into the Arno would increase the violence of the floods to 
which that river was very subject, and no decisive steps were 
taken. In 1606, an engineer whose name has not been pre¬ 
served proposed, as the only possible method of improvement, 
the piercing of a tunnel through the hills bounding the valley 
on the west to convey its waters to the Ombrone, but the 
expense and other objections prevented the adoption of this 
project.* The fears of the Roman Government for the security 
of the valley of the Tiber had induced it to construct barriers 
across that part of the channel which lay within its territory, 
* Moeozzi, Dello stato antico c moderno delfiumc Arno, ii, p. 42. 
