Thank you gadzooks for the tip on the book. I will be on the lookout for it!
Thank you Jeremy for your response as well. Most appreciated. No, I'm afraid I'm NOT looking at insulation. No insulation ANYWHERE under the house between the dirt floor of the crawl space to, nor between, the floor joists up against the old tongue & groove floor/sub floor. Just from wood to dirt and all air inbetween.