Unfortunate AJfuir.—The Marlboro (Md.)Advocate states that about a week agogentleman in Calvert county, named Bowou,found a runaway slave of a Mr. Nevitt onhis premises. Mr. 1J. attempted to arresthim, when ho mitdu a desperate resistancowith an axe, and finally Mr. Ji. fired onhim, and wounded him in the leg, fromwhich ho bled to death betorc assistance could bo obtained.