If you can, you'll need to give an appraiser a little more info to have it appropriately appraised.
What is the condition? What style bugle is it? What material is it made of and is it plated? Any markings?
Do you know who carried it in the Civil War? Do the letters, etc. prove it?
Was he Confederate or Union? (big difference in value)
What unit was he in? Was it a famous unit? Did the unit fight at Gettysburg, for instance?