looking for Chicago Reillys, 1890's-1900's ?

Looking for information about my great grandfather George Reilly and his brother, Father Dan Reilly.George was a Chicago fireman, and after retiring went into fire prevention business.George had at least one son, also George, my GrandFather.If anyone knows how to research fireman service records or histories, please let me know.Have no information on Dan Reilly, other than a reference to him in a communion card of my father's.I assume he was involved in a Chicago area clergy.

Thanks in advance.