11:29 am - Not quite as I imagined this
Whoops.
That ladder (which I did receive permission to borrow) is not, as I thought I remembered, an extension ladder. It's a single-piece straight ladder, and unwieldy as f***. I can't lift it into position myself from underneath. (Fortunately, in two tries, I managed to avoid putting it through my or my neighbour's window or dropping it on my head. Caught my shoulder instead.)
Next experiment: see whether I have a long enough piece of rope and am able to haul it up from the third-floor window without catapulting myself out the window. (Hey, if that happens and my cell phone and I both survive the fall, I'll blog the event straightaway. But I don't intend to lean far enough out to make falling likely.)
I did find a box of nails in the basement, and a lighter hammer than the one I was looking for, but unless I can get the ladder up, I'm still stuck. The rain has not started yet (well the pavement is wet so I guess we got a sprinkle when I wasn't looking -- no heavy rain and no thunderstorm yet) ... but the sky is dingy and the (disturbingly warm) breeze is quite moist. Wheeee.