Since my last post, the necessity of walking outside for almost an hour each day in the New England frost has driven me to seek warmth in such technologies as are readily available to the cost-conscious, internet-enabled cold person. My roommate recommended Uniqlo's Heattech line, and since there is now a Uniqlo in downtown Boston to which I can free-return any recommendations that did not pan out, I purchased a wide variety of supposedly self-warming (and simultaneously self-moisturizing!) leggings, tights, socks, and also yes, legwarmers (there was a $75 minimum for free shipping). They arrived. The sizing was wildly variable. I found the ones that fit and tested them on this fine 20-something-degree day.
Here is the verdict: Japanese technology can't fix the cold. Cold makes you feel cold. There is no getting around this misfortune. I wore the "extra warm" leggings under a pair of jeans, with the regular-warm socks and fleece-lined boots. The nice thing about Heattech is that it's thinner and softer than regular cotton leggings and socks. The less nice thing is that it's not noticeably warmer than them. It is somewhat warmer when you are inside and already warm, but expose the Japanese techno-miracle to the 21-degree day, and your flesh will still feel exactly like it's being exposed to a 21-degree day.
The legwarmers do look pretty fantastic, but I'm almost 30, so I think the time to wear fantastic legwarmers may be past. I am keeping one of each bottom though, because soft and thin are tangential goods, even if the longed-for good of warmth has yet to be found.