That is a rightious old J. Stevens Arms & Tool Co. double. Up thru Catalogue No. 52 they made doubles using the demi-bloc construction method. They were offered with either "high Pressure Steel", Twist, Damascus or Krupp Fluid Steel tubes screwed into the mono-bloc. By J. Stevens Arms & Tool Co. General Catalogue No. 53 (circa 1911) they had gone to chopper-lump barrel construction.