I really love these high school notebooks, kept by a Harry S. Nielson in 1919 for biology and hygiene class, with lots and lots of primitively hand-drawn diagrams, which I find immensely appealing and almost make me want to the subjects such as "how to locate the boiling point" and how magnets work. My favorite is a section off charts diagramming the proportions of water, protein, fat, carbohydrates and ash in various foods, from dried figs to bacon, wonderfully colored with crayon. Both notebooks feature gridded paper, and Harry creates title pages before each individual lesson. Really fun, and with a great pencil drawing of a massive arrow attack on the back of the hygiene book, which is most of the way filled, while the biology notebook is about half full. And a list of recent bird sitings on the back inside cover of the biology. Photos are not comprehensive but give a good sense. 

Each measures 9 3/16" x 5 7/8" x 1/2" and while they show wear they are in very good overall condition, pages clean and spines in good shape, all pages well bound. About 65 pages filled front and back (usually a diagram on left side of page and writing in the right) in hygiene notebook, about 35 filled front and back in biology. Sold as a pair.