In reply to Bob_the_Builder:
> (In reply to rgold)
> I'm trying to figure out what you mean here. Are you suggesting ab down the free end, set up new anchor, connect live rope (with hanging climber) to new anchor, pull free rope through the old anchor, abseil again from the new one?
Yes.
> If so, how do you pull the rope? I assume we have in this situation secured the injured climber initially with a prusik at the old anchor. That would prevent us from pulling the rope through surely?
No. You use the injured climber as a counterweight for the rappel, so that when you get the next anchor set up and the climber tied off you can just pull the rope as you would for any rappel. You have to know the rope tricks needed to shift the load of the injured climber hanging on the securing prussik to your counterweight; it is too complicated to explain here, but it is described in both "Climbing Self-Rescue" by Tyson and Loomis, Mountaineers Books, and "Self-Rescue" 2nd Ed. by Fasulo, Falcon Guides.