De pier van de Holland-Amerika Lijn in Hoboken, New York
From 1931, Cool was the secretary of the Koninklijk Instituut van Ingenieurs (Royal Institute of Engineers) and the editor-in-chief of De Ingenieur, a periodical for which he wrote and photographed. During an energy congress in the United States in 1936, he made a tour of power plants, dams, bridges, and the pier of the Dutch cruise line.