The aqueduct is dated securely by comparison with the work of Eupalinos at Samos as of the time of the despots. Two striking analogies are observable between the aqueduct of Peisistratos at Athens and that of Polycrates at Samos. These are the character of the pipes, and the system of shafts. The separate pieces of the pipes at Athens are from 0·60 m. to 0·61 in length, not counting the junction points. They are made of fine yellowish clay; inside they are protected by a red glaze, outside they are left rough, except that at each end they are glazed and have a double stripe of glaze round the middle and round each end. In length and diameter they correspond with the Samos pipes, which Professor Dörpfeld carefully inspected for comparison[271]. The Samos pipes also are actually decorated with stripes, only the stripes at Samos are incised, those at Athens painted. The same correspondence is notable in the way the pipes are joined together: both at Athens and Samos the pipes are soldered together with lead, and provision is made at both places for cleaning them. An elliptical shaped hole large enough to admit the hand is left, and is provided with a cover. A specimen of the Athenian pipes is shown in Fig. 37, and side by side with it a section of the conduit with the pipe in position. [Illustration: FIG. 37.] The pipes bear abundant traces of long use and frequent repair. In quite early days they seem to have got crusted with lime deposit from the water, and in some cases quite choked up, the water then flowed over the pipes and flooded the main channel to two-thirds of its height. In some places, where the rock was soft, it seems to have got worn away and fallen in, and portions of the tunnel became useless. New borings were made for about 30 metres and new pipes put in; these were quadrangular instead of round, but in the disused portion of the tunnel the old round pipes still lie about. Secondly, as at Samos, at intervals of from 30 to 40 metres, both tunnels alike are provided with shafts, which served when the tunnels were first made for the clearing away of the rock fragments, and which were made use of for the like purpose when the conduit was excavated. These shafts are sunk perpendicularly; one of them reached down to a depth of 12 metres, so low does the conduit in places lie. * * * * *