It may not be apparent from that page, but this is a translation of the English original, "Latin by the natural method", by William George Most, who was both a priest and a professor of Latin at Loras College, in Dubuque, Iowa. Victor Coulombe, a Jesuit scholar at Laval University in Quebec City, was impressed by it enough to translate it into French. And (to get to the point of this post), the English original is also available from the same website: https://cerclelatin.org/wiki/Most_versi ... first-year
Note that there are three volumes or books, for years one, two, and three, even though the French translation is only given for years one and two. I have checked the online library catalogue for Laval University, and it does appear that they have a copy of the French translation of the third year volume. So it appears that the third volume was translated. If so, it is a mystery to me, why they did not put it online as well, along with the first two years.
By the way, if one also prefers a pdf of the teacher's manual, the pages are available at hathitrust: https://catalog.hathitrust.org/Record/001724520
(If you wanted a single pdf file of the teacher's manual, I suppose you could download each page (there are around 50 pages), and then concatenate them into one file using some pdf tool.)
Note that Most's approach is rather different from that of Hans Orberg, of Lingua Latina per se Illustrata. He (Most) does not hesitate to give definitions of new words in a lesson, along with grammatical explanations. But after having studied these explanations, he wants you to concentrate fully on the text. At least, it seems this way to me. You can read the teacher's manual for a fuller explanation of his method. Also, more discussion of the method (in French) can be found on this page: https://cerclelatin.org/wiki/Home
(edited for typos, and small clarifications)