"Guarini's antenna with Ducretet method of suspension, from Henri Poincaré and Frederick Vreeland, Maxwell's Theory and Wireless Telegraphy, New York, 1904, p. 142" (caption and image from: Linda Dalrymple Henderson, Duchamp in Context: Science and Technology in the Large Glass and Related Works, Princeton: Princeton UP, 1998, ill. no. 103)