http://www.historynet.com/grenade-the-little-known-weapon-of-the-civil-war.htm/2
http://books.google.com/books id=q2j9vFcEswUC&pg=PA45&lpg=PA45&dq=%22Thunder+Barrel%22&source=web&ots=0KpOwywwhZ&sig=4txFqYbNbwdral1bcJZ76JX3Auo&hl=en&sa=X&oi=book_result&resnum=1&ct=result#PPA46,M1