Today's free book is The seven kings of Rome published by Frederick Warne (1876). For the table of contents, check at the bottom of this post below the image.
The book is available at UFDC (I have not checked for other online sources).
Table of Contents
Romulus
Numa Pompilius
Tullus Hostilius
Ancus Marcius
Lucius Tarquinius Priscus
Servius Tullius
Lucius Tarquinius Superbus
The Story of Pompeii