[On William Adams’ page of electronic resources on typography](http://members.aol.com/willadams/books-free-type.html)), I found a link to the Online Books Page) maintained by John Mark Ockerbloom, where on a lark I entered the keyword “Logic” into the search engine and made an exciting discovery:]

“Studies and Exercises in Formal Logic — Including A Generalization of Logical Processes in Their Application to Complex Inferences”) by John Neville Keynes, M.A.. Second Edition Revised and Enlarged. MacMillan and Co. London and New York. 1887. Digitized into pdf-files by the CWRU Preservation Department Digital Library.

John Neville Keynes (1852—-1949) was the father of John Maynard Keynes and thus—- as Larry Horn has quipped — the grandfather of modern economics. But what makes this find exciting is that his logic textbook contains one of the most extensive discussions of the problem of existential import of natural language quantifiers: Part II, Chapter VIII, “The Existential Import of Categorical Propositions”, pp. 137––160 [The chapter starts with the footnote “It may be advisable for students, on a first reading, to omit this chapter.”]. Here is a direct link) to the pdf-file including that chapter.