In a 1934 letter to Rimel Lovecraft remarks…

I have the entire series of Steele’s old ’14 Weeks’ textbooks […] which were wildly popular half a century ago [circa 1885] and which I still think are almost unsurpassed in giving beginners a good introduction to the science they cover.

These included Joel Dorman Steele’s A Fourteen Weeks Course in Descriptive Astronomy (1873), found in his library after his death. Joshi remarks in I Am Providence that of the old astronomy books found there…

some at least must have come from [his grandmother] Robie’s [astronomy] library. Of course, Lovecraft, ever the ardent used-bookstore hunter, could have picked up some of these titles on various book-hunting expeditions throughout his life.

Archive.org has several of the “Fourteen Weeks” series as scans, including the one on Descriptive Astronomy, though an 1875 edition.

In his reading guide for Anne Tillery Renshaw he calls the one in Physics “antediluvian” and classes it among the “whiskered reliques”, but still rates the ones on Chemistry and Zoology…

For a sound elementary introduction read Steele’s ancient Fourteen Weeks in Chemistry

Steele’s old Fourteen Weeks in Zoology is an easy start, and not at all misleading.

This might sound strange to us, but it’s no different than someone in 2022 recommending books from 1972 or thereabouts. Just as we might now still want to recommend a Carl Sagan or a Richard Feynman book to a beginner.

None of the mentions tell us when he acquired the set, though it must have been before 1934.