Contour map of Gulf of Mexico as sounded by the C&GS Steamer BLAKE
between 1873 and 1875. Over 3,000 soundings went into this chart, most of the
deep water soundings beween taken by the Sigsbee Sounding Machine. This was the
first realistic bathymetric map of any oceanic basin. In: "Three Cruises of
the BLAKE" by Alexander Agassiz, 1888. P. 102. QH 93.A26 1888 v.1.