WASHINGTON, Wednesday, March 20. CONCERNING FORT SUMPTER. While the most prominent Republican Senators are unable to say definitely whether the order for the abandonment of Fort Sumpter has been actually issued, they all now concede that this policy has been definitely settled upon. APPOINTMENTS MADE AND TO BE MADE. The following nominations were sent to the Senate to-day: ANSON BURLINGAME, of Massachusetts, Minister to Austria. HENRY S. SANFORD, of Connecticut, Minister to Belgium. RUFUS KING, of Wisconsin, Minister to Rome. BRADFORD R. WOOD, of New-York, Minister to Denmark. JAMES O. PUTNAM, of New-York, Consul at Havre. FREEMAN H. MORSE, of...