This was effected by caissons with air.
The piers of the Benares bridge were single iron caissons, 65 ft.
At the Forth bridge iron caissons 70 ft.
These uprights are supported on huge piers of masonry and concrete, the foundations for which were carried down, by the aid of iron caissons and compressed air, to a depth of about 15 metres on the side next the Seine, and about 9 metres on the other side.
The lower course of the Tiber has been from the earliest ages subject to frequent and severe inundations; of more recent ones, those of 1598, 1870 and 1900 have been especially destructive, but since the year 1876 the municipality of Rome, assisted by the Italian Government, has taken steps to check, and possibly to prevent these calamities within the city by constructing embankments of stone, resting on caissons, for a total distance (counting in both sides of the river) of 6 miles.
Cossacks, foot and horse soldiers, wagons, caissons, and cannon were everywhere.