Robert Indiana kept a series of illustrated journals during the late 1950s and 1960s, in which he discusses the development of his work as well as his daily life on Coenties Slip.

In his journal entry for July 4, 1962, Indiana describes a quiet Fourth on the Slip, recording that he "stayed in the full day, sunning for a couple of hours on roof with J. [his partner, fashion designer John Kloss]," and "constructing." He notes that he worked on the sculptures Gem and Mate. The entry includes a sketch of the latter, to the right of which he indicates that he added numerals to both wheels, which he painted orange in the top wheel and white in the lower one. Below the sketch he records that the work is oil, iron, and gesso on wood, and that it measures 41 x 12 1/2 inches.

Indiana also writes that he listened to President John F. Kennedy's speech on the roof, and that he watched the fireworks from there with his cat Particci.