Board of Water Supply. City Water Tunnel No. 1. Geological test borings on northeast corner of Clinton Street and Monroe Street. Showing Keystone rig. October 4, 1910.

Board of Water Supply. City Water Tunnel No. 1. Healey Sewer Machine & Construction Company. Geological test borings on corner of Clinton Street and Monroe Street. Showing American Diamond drill making borings to investigate geological conditions deep below the pavement in preparation for City Water Tunnel No. 1. Borings are cylindrical samples that reveal the depth to and character of the rock. December 3, 1910.