Narrow Kscapks from Drowning.—There Were two narrow escapes from drowningin the riv^ yesterday afternoon,John Denhis, a colored youth was engaged inpicking conl ’from the dumpings of the citydredge, on one of the scows. One of thedumpings fromUhc bucket of the dredge jarredopen a gale of the scow, uud with a large quantity of sand, Dennis slipped off into the water, going to the bottom of the river, When be rose he managed to grasp a chain attached to the gate, and to support himself until he could be rescued by his father.