The bike is an American made Reading Standard. Sorry I can't tell you that much about the make. They were very early on the scene, before 1910, and faded away sometime in the 1920's.
They were built to the typical US formula. A big vee twin engine in a sturdy frame and intended to survive hard work on rough roads.
I'm sure someone can give you more specific information now you know the make.
Cheers, Bob