Pages 51 and 52: “IL FINE DELLE PROPOSITIONI”, it says in the bottom of page 51, meaning that the introduction is over. Page 52 is the first page of the chapter about the “prima regola”.
Pages 88 and 89: On page 88 you can see one of only 4 (including the title page) shaded and detailed drawings in the book. Throughout the rest of the book there is mostly text passages accompanied by a lot of simple drawings and sketches, which never go into such a level of detail.
Pages 98 and 99: This spread, starting on page 98, marks the beginning of the “seconda regola”. Right underneath the header and the name of the author there is am small note that, roughly translated, says “a few definitions that are useful to know for a better understanding of the seconda regola”.