Leonardo described part of this manuscript as “a collection of notes without order, composed of many pages which I have copied, hoping then to put them in their appropriate place, according to the topics that they treat”.

The sheets of this manuscript deal with a variety of mainly technical and mechanical subjects, such as weights and geometry, as well as architectural studies related to the residence of Francis I at Romarantin, France. The manuscript also contains an ingenious design for a device for breathing under water.

The Codex Arundel is a bound manuscript containing 238 pages of various sizes that have been gleaned from other manuscripts.