MISCELLANEOUS. ALARMING INCIDENT AT WASHINGTON. The "New York Times" letter from Washington states that on the 5th of February, as the police-officer was passing the President's house, he saw a man on horseback in the portico trying to ride in at the front door. The officer took the adventurous horseman into custody, and turned him over to the stationhouse, where he gave his name as JOSEPH G. SYPHER. On his person was found a loaded pistol, and after being searched, he was locked up and kept until he could be conveyed to the police-court and charged with carrying concealed weapons. After hearing the case, the court imposed a fine of 30 dols. It is stated that SYPHER has been lounging about the Executive mansion for some time, and has latterly been denied admission, but it seems he determined to make a tour of the house on horseback. He had no excuse to offer. It is thought by the officers he is slightly deranged. Only "slightly ?"