Depths shown by gradient tints.
"A. bis (Upper sheet) U.S. Coast Survey A.D. Bache Superintendent" at head of title.
"No. 2" outside upper left margin.
Includes inset map "Rocks off Portland Harbor, surveyed in 1864", scale 1:200,000.
Removed from: United States Coast Survey, Annual report of the superintendent of the Coast Survey (1864).