Well, it seems that all I have accomplished is "art" with the bricks. I stuck them together temporarily, fired up a torch near the fire hole and stuck in a small piece of O1 I had trimmed from the knife. After about 20 minutes, it was just barely glowing toward one end. I also noticed the bricks were getting warm on the outside. I hit the 'net in search of answers, and found that there are definitely two types of firebricks - the hard ones like I have, and the soft, AKA "insulating" bricks. I found a chart showing that the thermal conductivity of the hard bricks is on the order of 10 times as high as the soft ones. That explains why they just soaked up the heat, as opposed to containing it. So, my masonry work was to no avail. The good news is, I have some of the proper bricks on order, as well as a few of them that a friend has graciously gotten for me from where he works. I should be back on track in a day or so.