The book mainly consists of illustrations whereas the text works as a describing factor. You could go as far as saying the book could work without text since the drawings are very clear and the main objective is to show different layouts of fortresses. Therefore the book is most likely an academic study.
Depending on the page the text is differently distributed on the site. If there is an illustration on the site most of the times the text works as describing element or as caption and is located on the edges of the illustration. When working as a description the text is usually put in a box. Pages consisting of text only are organized by a horizontal box either covering the double-page spread but the words continuing to the bottom of one site before commencing the next page or a horizontal box just on one site with margins on each side. The book is handwritten with a consistent hand. Rather big margins are used for text and illustrations which creates a very centered notion.
There is a variation of illustrations. In the beginning of the book there are several registers explaining geometric shapes and angles which will be used in the rest of the book. Following these are the main ground views of fortifications. The layouts are either on double sides or also in register form. The ground views are sometimes accompanied by the profile of the respective. The rest of the book mainly consists of maps of then existing fortifications in different parts of Europe and therefore different terrains. The terrains are being more specified by frontal views of buildings and nature around the ground view.
Basically all of the maps and ground views are foldout spreads, so are the registers. There are only a few illustrations presented on a single full page.
Each drawing has a title which either works as numbering reference if it is one of the theoretical ground views or as a geographical reference to where the actual fortification is built.
Sadly the OCR was not able to recognize the text oft my book because it is handwritten. As alternative I’m using the text “Architecture Essay on Art” by Étienne-Louis Boullée. Both of the books are academic studies as it seems. The difference is that the book by Nikolas de Fer is analyzing the fortifications which were used in the past while the new book is about visionary architecture of the future.