00:02To build the tunnels on the Nîmes aqueduct, the Roman engineers first marked out the stretches,
00:08then they redefined them, and finally they sunk vertical inspection shafts at regular distances.
00:14When they reached the bottom of the shaft, they dug the tunnel in both directions,
00:19following the direction indicated with the help of plumb lines.
00:28This all had to be undertaken, paying careful attention to the level of the ground,
00:33which was key to the success of the conduit.
00:36The conditioning factor was the gradient, which had to be carefully controlled throughout the tunnel,
00:41with the entrance and exit levels linking perfectly.
00:45To achieve this, it was necessary to check the levels constantly and carefully, especially by using a water level.
00:52The level of water.
00:55The level of water.
00:55The level of water.
00:56The level of water.
00:56The level of water.
00:56The level of water.
00:57The level of water.
00:57The level of water.
00:58The level of water.
00:58The level of water.
00:59The level of water.
00:59The level of water.
00:59The level of water.
00:59The level of water.
