When looking up information about Al Spalding I found a lot of interesting stuff, particularly about how baseball leagues functioned at the time. The National League was established in 1876. William Hulbert convinced great players to switch teams. In 1876, the National League had eight teams in it, four from the East and four from the West. Surprisingly I also found out that teams were named after the socks they wore, like the Boston Red Stockings and St Louis Browns. In March of 1876, Hulbert convinced three other players to move to Chicago but I am having trouble on finding how much they made.
Al Spalding, The A. G. Spalding Baseball Collection at the Stephen A. Schwarzman Building / Photography Collection, Miriam and Ira D. Wallach Division of Art, Prints and Photographs http://digitalgallery.nypl.org/nypldigital/dgkeysearchdetail.cfm?trg=1&strucID=137988&imageID=56180&word=albert%20spalding&s=1¬word=&d=&c=&f=&k=1&lWord=&lField=&sScope=&sLevel=&sLabel=&sort=&total=575&num=0&imgs=20&pNum=&pos=13