I just came across a very nice review of Twirling Jennies from back in October on Capering & Kickery, a dance history site. Being the first review I’ve seen from a serious dance historian, she’s found some errors, alas. Elias Howe, the dance master, was not the same Elias Howe that invented the sewing machine (although they were born a mere year apart, and confusing the two is not uncommon). And The Lancers Quadrilles go back further than Twirling Jennies states. But beyond that (and some other lesser technical quibbles), she’s quite enthusiastic.
So, my apologies for the errors. Much as I would have liked everything to be perfectly accurate, it comes as no surprise that, with all the detail crammed into the book, a few mistakes were made. Happily, that is what second editions are for!