I have been looking for a website that will help explain the various Muster Rolls used by the Union Army in the Civil War, but have had no success. I have found my ancestor on (Landgraebers'/Pfenninghausen' First Flying Battery) Company Muster Rolls, Battery Muster Rolls, and Special Muster Rolls, and I would love to know what each card represents.

Also, if a person was left sick in a hospital, and not present on the Battery Muster Roll, was there communication from month to month to determine if that individual was still present in that hospital? It seems as though the same information appears on each Battery Muster Roll--"Left Sick in Hospital in Rolla". How often did they actually check on those soldiers?

Any help you could give me would be truly appreciated.
Thank you so much for you time,
Lisa R.