Oloren

Ignoring the disappearance of the elemental, the elf bends slightly to look at the underside of the disk and announces that without the weight for motive power, the rest of the device should be unable to generate electricity, and therefore harmless. Straightening, he eyes the rope under the stone and asks "Prodigious feats of climbing aside, is anyone else able to fly? Failing in a more elegant solution, do we have enough rope between us for that depth?" As he speaks, he walks to the edge and drops a small rock down the shaft, counting seconds until he hears a splash.
Spoiler
Show
How much rope is coiled under the capstone?
How rough (climbable) are the walls of the shaft?
Would you allow a very high Int character to determine the depth by counting seconds until the splash? It requires the character to be aware of gravitational acceleration, but that's it - the rest is simple math. (4.9*numbers of seconds squared gives the answer in meters, if my calculations are correct)