In reading the essay I noticed a casual reference to the MHS, and that sent me into Jenks' papers there, where I found a few more mentions of he Memoir among Jenks' diaries and correspondence, including the anonymous letter he sent with the manuscript to the publisher. I also did some newspaper searching to suss out anything I could be the reception of the pamphlet, and found some interesting advertisements as well as some evidence that many copies were probably purchased at a sheriff's auction of the printers' inventory (and likely met a sad end). For all that, go here.
Fast-forward to 4 February, when bookseller Garrett Scott (who's always got great material, by the way) emails to say he's going to be listing a copy of Jenks' pamphlet, and asks to use some bits from my MHS blog post. I agreed, of course, but then just had to buy the pamphlet myself. It arrived on Thursday, and on Saturday I took it over to the NEHGS to have it scanned, since I very much want folks to be able to access the text in a straightforward way.
I'm now happy to report that the images are available via the Internet Archive, here, and I've made a transcription as well, which I've posted as a PDF.
This copy of the Memoir was deaccessioned from the collections of the Long Island Historical Society (now the Brooklyn Historical Society), and used to have a name on the title page, but it's been excised, eliminating the record of the pamphlet's early owner.
I'm delighted that Jenks' text will now be able to reach a wider audience - enjoy!