Bells book I just got Bell s book IMO he was about as good as Feynman in explaining matters If you don t have it I can send you a scan of the intro to his spaceship discussion in his chapter How to teach special relativity BTW I fully agree with Bell when he wrote that those who know something of the reasoning of Larmor Lorentz Poincare and Einstein have stronger and sounder instincts he propably meant sounder instincts than mathematicians Regards