I remember the passionate work of my father who from 1928 to 1939 dedicated his skills as a hydraulic engineer to the partial draining of Lake Nemi, lowering it by means of a floating pumping station with pumps provided by Costruzioni Meccaniche Riva of Milan.
Engineer Guido Ucelli oversaw the indispensible restoration of the roman conduit that permitted the discharge of the water into the neighbouring valley of Ariccia.
This restoration allowed us to discover the techniques of ancient roman civil engineering and to document that the said gallery was realised by boring simultaneously from both sides, that is to say from both the Lake Nemi side and from Valley Ariccia to meet in the middle.
The knowledge of surveying practices allowed the ancient Romans to construct the gallery with the minimum of errors, both on the horizontal plane and on the vertical, notwithstanding the great difficulties involved owing to the blocks of porphyry that necessitated deviations in the tunnel since they did not have tools that were able to bore through this material at that time.
The recovery of the ships then allowed us to ascertain with certainty the advanced state of Roman knowledge of naval construction.
The hulls were covered with a layer of wool fabric impregnated with tar and by a layer of lead about 3mm thick, to impede the attack of marine organisms and borers, even if, in the case of fresh water, such treatment was not strictly necessary.
The two layers of wood and lead were fixed to the hull with copper nails of the purest quality, that today would be called electrolytic copper: which raises interesting questions in the area of Roman metallurgy.
Two types of bearings were discovered on the ships, one of ball bearing type with the ball bearings made out of high resistance bronze and the other a needle bearing type, with the rollers made out of hard wood.
It is not known to what use these large diameter bearings were put; perhaps to mount astronomical equipment or even statues.
Another exceptional discovery was that of an anchor with moving jaws, over 2 metres in length. This design was later introduced into the Royal Navy of Admiral Nelson in the 18th cent. After this discovery, this design of anchor was renamed "Roman anchor."
Extraordinary discoveries were made especially in the metallurgical field. In fact, every metal and alloy used, for example bronze, was perfectly adapted to its use and corresponded, incredibly, to the German DIN standards.
Another exceptional find was that of a conical bronze tap of 140 mm diameter, that connected to the aqueduct to re-fill the water tanks of the ship. This tap was found, at the time of its discovery, to form a perfect hermetical seal without the need for gaskets.
Not being able to linger on the subject of the interesting technical finds on the ships I cannot finish without saying that Guido Ucelli, in collaboration with the Italian Navy, carried out water tests on models of the two hulls resulting in extremely low coefficients of friction for ships of low velocity propelled either by oars of sail.