http://www.bootslap.com/apps/articles/default.asp?blogid=0&view=post&articleid=Music-Publishing&link=1&fldKeywords=&fldAuthor=&fldTopic=0

There are two general rights covered in a music copyright: the authorship of a song and the ownership of a song. According to Copyright Law, the writer is the natural owner of every song they write until ownership is assigned to someone else. Every song is made up of two equal parts; not the lyrics and the melody but the writer share and the publisher share.

http://www.bootslap.com/apps/articles/default.asp?blogid=0&view=post&articleid=Mechanical-Royalties-and-Licenses&link=1&fldKeywords=&fldAuthor=&fldTopic=0

This is really important because a lot of people don't know the difference between Royalties from Sales and Mechanical Royalties so i thought this might help you too.