I'm doing the quest for Septimus, but I'm stuck. I passed through the Anionculory and reached the big shaft or pit, but I can't find the way down. The only ramp I can find, the first on the right, leads to a dead-end with a chaurus nest ahead, a door that leads nowhere on the right and a deadly drop-off on the left. I tried jumping down onto a pipe and then to another ramp, but Lydia was killed trying to follow me. There must be another way. I did it once in another character, but have forgotten how.