You know I love a book that has lived a life, and this is very much one of those--I think its original seafaring owner likely slept with it under his pillow!  The book is Seamanship Examiner and Instructor of Masters and Mates for the Marine Board Examination in Canada by John St. Vincent McNally, published in 1873. Photos give a good sense: the endpapers are entirely consumed with notes and calculations (including related to the positions of stars), with some great little drawings of flags, too; and the (heavily turned) printed pages are annotated here and there with more notes. In addition to the handwritten stuff, I love the plates, including a pair of color charts of signal flags, and several more pages of signal alphabets and semaphore. It's rough but I think it's pretty cool, and holding it in one's hands is to feel rather as if at sea oneself, navigating through the dark of night!

 8 3/8" x 5 7/16", 120 pages. Very much worn, with tears to pages here and there, covers almost entirely unreadable, and spine very much cracked, but it is mostly still holding together and I love it!