There is an ad in the August 8, 1864 issue of the Missouri Republican for a book entitled The Finger-Post to Public Business. The subtitle of the book is Containing the mode of forming and conducting Societies, Clubs and other Organized Associations and the ad mentions that it contains the "Rules of Cricket, Base Ball, Shinny, Yachting and Rowing, and Instruction concerning Incorporations..."
Being the industrious fellow that I am, I thought I'd see if I could find a copy of this book and, it just so happens, that there is a copy online at Google Books. It turns out that The Finger-Post to Public Business contains the "Rules and Regulations Adopted by the National Association of Base-Ball Players, Held in New York, December 11, 1861."
The 1861 rules (or the rules for the 1862 season) are interesting in themselves but they are not as significant as the 1857 rules, which defined the modern game, the 1858 rules, which allowed the umpire to call strikes on the batter, the 1860 rules, which introduced the batter's box, or the 1863, which allowed the umpire to call balls. I don't consider myself to be an expert on the minutia of 19th century baseball rule changes but those four sets of rules, I believe, are the most significant of the antebellum and war years. I haven't gone through the 1861 rules in detail but it may be that they introduced the use of chalk foul lines, which is a unique distinction.
More importantly, we see here, in the use of newspaper advertising, a way in which the rules of baseball were spread from New York throughout the country. The Finger-Post was a book published in New York and it could be purchased from the publisher by anyone in the United States for $1.50. Send your money to New York and you would receive your book in the mail. Simple enough. But if it wasn't for the growth of daily newspapers in the antebellum era, someone in St. Louis would never have discovered that he could have purchased the book. When we talk about the growth of baseball and its spread outside of New York, newspapers and the new information technology of the era are an important part of the story.