Wilson chatted along for awhile, and presently got Roxy’s fingerprints for his collection—right hand and left—on a couple of his glass strips; then labeled and dated them, and took the "records" of both children, and labeled and dated them also.
Two months later, on the third of September, he took this trio of finger marks again. He liked to have a "series," two or three "takings" at intervals during the period of childhood, these to be followed at intervals of several years.