Career
She became an active participant in the Woman"s Christian Temperance Union. In 1887 (at age 44) she moved to Los Angeles, California and started collecting seashells. lieutenant was in Los Angeles that she became active in malacology, the study of mollusks.
She researched the marine family of gastropods, Mitridae, the miters.
Williamson maintained a correspondence with William Healey Dall and J. G. Cooper. The minute marine gastropod Vitrinella williamsoni was named in her honor.
Her papers are held in the collection of the Smithsonian Institution Archives.