Hank’s Book of Eukadidles for the Ukulele (1923)
This book is, according to the cover, "A collection of ditties, camp songs, and jingles arranged for the ukulele by Hank Linet using the approved ‘Played-on-Sight’ Ukulele Chord System."
The most common tuning in the 1920s was A-D-F#-B (a whole step up from the modern C tuning), and that is the tuning that is used in this book. The chord forms themselves will be familiar to you if you’re used to playing in C tuning. If you’re playing along with the actual melody as written in the standard notation in the book you should retune your uke (or transpose the notes down a whole step), but if you’re just playing the chords as written and already know the tune you can just stay in the standard tuning that you’re used to.