In 1937 Calder was one of the contributors to the Pavilion of the Spanish Republic designed by Josep Lluís Sert for the International Exposition in Paris, where his Mercury Fountain was installed in proximity to Picasso’s painting Guernica. In the middle of the Spanish Civil War, Calder showed his support for the embattled Republic by creating a fountain that would run with mercury from the mines at Almadén – a valuable economic and strategic resource. 

Two years later, he participated in the New York World’s Fair. If the Paris Exposition reflected the stark confrontation between socialism and fascism, the 1939 Fair was a celebration of business and enterprise. Calder created models for three ‘ballet-objects’, including Dancers and Sphere, each of which resembled a miniature stage upon which different elements would revolve to create a choreographed movement. In addition, Calder envisioned a spectacular ‘ballet’ to be performed by the jets of water leaping into the air from the fourteen spouts of a fountain outside the Consolidated Edison building. Although the jets were installed around the building, the ballet was never executed. According to Calder, the engineer attached to the project was never really interested in making it possible.