I don't know if this book is any good, but today, it's free: Extraordinary Popular Delusions and the Madness of Crowds. Some comments in the reviews indicate that this is only a small portion of the complete book.
I don't know if it is good either, but it is always free from the Gutenberg Catalog. As are most books prior to the 20th century that one is likely to have heard of.
I don't know if this book is any good, but today, it's free: Extraordinary Popular Delusions and the Madness of Crowds. Some comments in the reviews indicate that this is only a small portion of the complete book.