<HTML>Being a performing cellist and an RPT gives me a unique perspectivre on this issue. My wife and brother are also professional violinists. At one time, I was a member of a professional string quartet, which at upper levels of performance spent at least half of our rehearsal time on intonation. Very few string players actually play just major thirds. If they did, the resulting half - steps would be so roundly criticized by peers, they would be professionally forced to abandon the practice. Most strings players have been taught (myself included) that the requirements of closer "leading tones" means that the "just" major third is wider than the tempered major third. In string quartet circles, it is well known that one of the most common reasons for quartets to break up is disagreement over the proper width of major thirds. Due to the nature of the literature and competition, quartets must work extensively on intonation to succeed. Careful listening to recordings reveals a varied approach. I have only heard one performance of a well known quartet that even approached just major AND minor thirds. Some play wide thirds, some slightly narrow to ET( about 9 cents wide, to take a guess). Just majors thirds would sound so radically wrong to our current listening public in most contexts, that to play that way  regularly would be professional suicide. Baroque performing groups are a different matter. Many new groups are playing with "Baroque" pitch and using closer to just thirds. Very few go all the way to real purity, though. This, of course, depends on the era of "Baroque" being played. Mean tone tuning was common through most of the Baroque, although the most commonly performed composers (Bach, Vivaldi, Telemann, Handel) clearly expected Well - Temperement. However, some such as Corelli, would never have heard Well - Temperement. Try a violon sonata of Corelli in real Mean tone tuning if you want to shake up your colleagues! When we talk about "string " intonation, therefore one cannot assume that the approach of one or a group of players is representative of the whole. I could easily alienate all of my colleagues by engaging in a harangue about real just major thirds. Most would tune out at my insistance over their real narrowness, thinking that regardless of my apparent knowledge and professional involvement as a tuner, that I was carrying on a fringe, eccentric argument which was well out of mainstream understanding. This, by the way, includes my wife, to a degree! This is because violinists have been taught to "avoid" the trap of playing with the "corrupted" equal temperement piano (like it was evil). They are taught to think that the evil piano tuner is convinced of his/her superiority of equal temperement, and is trying to force it on otherwise unsuspecting "real" musicians. There is no other subject which generates such intensity as a discussion about intonation amongst musicians. Most fear more than anything to be accused (especially correctly) of being "out of tune". My brother, when attempting to understand the basics of piano tuning, realized what a difference there really was on this issue and was shocked, despite being relatively informed that just major thirds are narrow. If you (Bradley) are doing research on this subject I would be interested in helping. Perhaps I could give advice on how to set up your tests or some such help.</HTML>