It would need one strong enough to support the body of a man--and that, too, while engaged in the violent exertion of climbing.

The rope would require to be of great length--two hundred yards or more; and every yard would add to the weight the eagle would be required to carry up.
It is not to be supposed that they intended to "swarm" up this rope hand by hand.

For the height of a dozen yards or so, any of them could have accomplished that.

But there would be a hundred and fifty yards of "swarming" to be done before they could set foot upon the top of the cliff; and the smartest sailor that ever crawled up a main-stay--even Sinbad himself--could not have done half the distance.

They had foreseen this difficulty from the very first; and the ingenuity of Karl had at once provided a remedy for it--as will be seen in the sequel.
The second question that presented itself was:--admitting that the bearcoot might bear up a rope stout enough for the purpose, whether there would be any possibility of getting this rope stayed at the top?
Of course, they could do nothing of themselves; and that point would be a matter of mere chance.