Tunnel of Eupalinos
37.69388888888926.93Koordinaten: 37 ° 41 ' 38 "N, 26 ° 55' 48" E
The tunnel of Eupalinos is part of a water pipe, the (now Pythagorean ) in the 6th century BC to supply the Greek city of Samos was built on the island of the same name. The tunnel is the second known tunnel in history which was built in Gegenortvortrieb, and the first in which this was done according to a carefully prepared plan. With 1036 meters length of Eupalinos tunnel was also the longest tunnel of its time. He is now a tourist attraction and forth from the south entrance to a length of about 150 m walkable. The north entrance near the Agiades source is reachable by a footpath, but closed by a gate.
Construction
The Eupalinos tunnel is named after its architect Eupalinos of Megara, whose name was from the Greek historian Herodotus ( 482-424 BC) handed down to posterity ( Histories 3, 60). In addition, nothing is known about the person of the Eupalinos. About participation of the Greek philosopher and mathematician Pythagoras of Samos (ca. 580-500 BC), who could have stopped at the time of the construction of the aqueduct in his hometown, and his Pythagorean geometry could have come to the application, it has been speculated without it, however, are concrete evidence of this.
As a builder of tunnels, the tyrant Polycrates of Samos is traditionally (reigned 537-522 BC), known in the older literature. However, talk recent research by Hermann Kienast ( German Archaeological Institute of Athens) were made to the tunnel and for the first time included the whole complex, for a slightly earlier completion date ( 550-530 BC ). Estimates of the construction period ranging from eight to 15 years, with Kienast takes a Construction period of about ten years. Overall, the water pipe more than 1,000 years was in operation until it has been neglected in the 7th century AD and eventually abandoned.
Research
The rediscovery of the tunnel by a local abbot in 1882, goes back to Herodotus, who reported the first ( and only) ancient writers from the tunnel and described him with enthusiastic words ( Histories 3, 60):
"I 've studied a little longer with the Samians, because they have listed three of the most powerful structures of all the Greeks: they pierced a mountain of 150 fathoms height from the bottom and dug a tunnel with two openings. Its length is seven furlongs, the height and width of eight feet. Due to its length, another channel is performed, twenty cubits deep, three feet wide, through which the water is directed into tubes to the city; he comes from a strong source. Builders of this tunnel was Eupalinos from Megara, son of Naustrophos. That is one of the three buildings ... "
The archaeological research of the water line was mainly driven by the DAI since then. 1883 was made by the German archaeologist Ernst Fabricius first scientific inventory. After the tunnel for nearly a century was again neglected until it was completely cleared in the years 1971-73 by the DAI Athens under Ulf Jantzen and made available to the research. The architectural historian Hermann Kienast 1995 published the final inspection of the facilities. Other authors have dealt mainly with the question of how it was possible Eupalinos to merge the two headings as accurate.
Overall plant
The Eupalinos tunnel is the middle section of a water pipe that connected the town of Samos with the source Agiades and it crossed the 230 meter high mountain walls. The aqueduct can be divided into three sections:
- A 900 meter long underground pipeline from the source to the northern slope of the mountain. This section was outside the city walls.
- The 1036 meter long Eupalinos tunnel, which traverses 180 meters below the summit of the ridge over its entire width.
- A 500 meter long underground pipeline from the southern slope of the mountain to a well house in the city. This section was within the city walls.
The reason for the underground course of the aqueduct was probably in the fear that the water supply of the city could easily be cut in a siege from the outside otherwise. Overall, had to build about 7,000 cubic meters of bedrock to be excavated, of which 5,000 cubic meters attributable to the tunnel that had to be driven by solid limestone rock. With an average of 1.80 meters and 1.80 meters wide, the tunnel has almost a square cross section. The tools were used during the driving solely hammer and chisel.
Duct
The Eupalinos Tunnel has virtually no gradient. His exit point is the same as its entry point at 55 meters above sea level. For the necessary incline toward the city made a second, narrower duct, who was beaten on the east side of the tunnel in the floor and on the ground was the actual water line. This channel is almost 4 meters deep into the mountain at the entrance of the tunnel and reached the tunnel output a depth of 8.90 meters. This enormous depth is explained that the source mirror had already lowered in the course of construction, so that the water-conducting channel had to be set deeper.
The reason for the double construction of tunnels and duct, which is also found in other tunnels of time surveying constraints are adopted. Since it " then no adequate measurement instruments was to determine a slope of less than 1%, but it was good with instruments such as the chorobates able to the horizontal plane to keep", it must Eupalinos first have gone about the two jacking sure to merge the mountain. Were once connected to each other the two studs, you could knock out in the second step the necessary gradient of the tunnel floor, without having to take the risk that miss the two headings.
Gegenortvortrieb
Two things had to determine as accurately as possible, so that the two teams met in the mountain the Builder Eupalinos:
- The level of inputs;
- The drive direction.
Both problems were solved by Eupalinos masterly manner how the execution of the tunnel reveals. Thus, the tunnel floor at the junction of the North and Südstollen only a height difference of 60 cm, which corresponds to in relation to the total tunnel length of a difference of less than 0.125 percent.
It is unclear, however, why both tunnels meet at nearly right angles, as if the two teams kept the original, straight forward drive direction, so there would have been an almost perfect meeting of the two tunnel halves. It is noticeable that the north tunnel deviates first from the ideal direction of the course and after a few hundred meters begins in the mountain to build broad zigzag bends, whereas the south tunnel makes only after 425 meters straight course a sudden bend to the right, with the northern tunnel to connect. One reason for the change of direction in the north tunnel might have been to avoid aquifers or soft rock, which would have meant the danger of collapse. The kink in the Südstollen would therefore be interpreted as a reaction to the change of direction in the other tunnel. Conceivable and not entirely illogical would be to interpret the multiple slight change of direction in the straight line as consideration of the defense strategy, because inflection points, also slightly curved manner, always provide a " shield" against the coming from the other direction attackers dar.
Simple but effective was the method by which Eupalinos ensured the meeting of the two studs. As he left, turn both headings in the final meters together sharply to the east, he worked against the danger to dig two parallel tunnels, and made a cutting point is unavoidable, provided the two studs were on the same level, which was the case. Top view:
The almost rectangular meeting and the slight difference in height of both studs are in the scientific discussion as clear evidence of the first scheduled Gegenortvortrieb in history. The fact that not a single vertical shaft was dug to the entire 1036 meters in length, the Eupalinos tunnel, borders clear from the qanat construction and makes it the longest tunnel of its time.
Surveying method
Given the precision of the tunnel Eupalinos modern science has dealt with the question of which measurement methods of the ancient builders might have used in the tunneling of the mountain. Since Herodotus has left here about any information that scientists have to rely on archaeological evidence and mathematical calculations. The focus is on the question of how Eupalinos has determined the level of inputs and the driving direction. Here, two approaches can be distinguished:
- Surveying around the mountain ( Heron of Alexandria, Apostol );
- Survey over the mountain time ( Toulmin & Goodfield ).
The problem with both ways in the accumulated measurement uncertainty, which can very easily lead to considering the length of the tunnel, that the two studs missing in the mountain. The first scientist who had ready a mathematical solution for how to build a tunnel in Gegenortvortrieb, was Heron of Alexandria ( Dioptra, Chapter 15). His theoretical approach was long regarded as the method that had to have used Eupalinos until in the 1960s Goodfield Toulmin & met with a local visit to considerable topographical difficulties in horizontal bearings along the mountain. Therefore, they prefer instead the measurement by means of ranging poles along the ridge. The mathematician Tom Apostol, however, this method is considered due to the large number of individual measurements for an error-prone and keeps the measurement around the mountain using simple auxiliary instruments for practical.