Thanks greatly, Rob, Andrew, NeoTech!

You make it useful to report this kind of thing.
Andrew, in answer to your question yes I did keep adding charcoal, -- I went though all of the charcoal I had -- but only after I realized it had evaporated so fast. And even later added a second metal charge (which didn't help anything). I went through 14 gallons of charcoal. The furnace had been preheated with wood for an hour with blast on, and charcoal, as well as a heat soak period with metal.
Just as observations which may help others on this particular path, I do believe that the iron layer tended to choke up the exhaust and force it out the tap hole. The tap hole was left open to look for the first iron, per most cupola books. But it hardly showed up. I do believed the open tap robbed some heat from the upper cupola and kept it low -- near the tuyeres -- but probably there just wasn't enough heat altogether for the quantity of metal. If there'd been an excess, fire would have come out of every nook and cranny! Well maybe the lid contributed to this upper restriction problem. The lid also tends to stop you from adding -- you can't see what's going on inside, and don't want to cut the blast to check, while melting. So maybe the lid was part of the problem, too.
I should some day try it with the lid off, and try melting a 3 pound charge. But don't have the motivation right now. Not saying it would work, but might be useful to just see what the difference was.
I'm going to work on the oil fired side of iron melting in this furnace. I really want to do some casting and think less about the furnace construction itself. Thank you all again.

(Shot of one fused chunk of cast iron found in the drop -- shaped roughly like the well. About 5 pounds.)
