From a June 18, 1931 New York Times article,
Captain Gustav L. Brown served on the Eleanor Bolling, supply ship of the Byrd Antarctic expedition. Captain Brown has resided in Brooklyn since his return from the polar regions and he will make his future home in Baltimore.
On May 23, 1930, the 71st Congress directed the acting Secretary of the Navy to have gold, silver and bronze medals made for the Officers and men of the Byrd Antarctic Expedition. 81 people connected with the expedition were awarded medals, including Captain Gustav L. Brown, as Master of the Eleanor Bolling.
https://en.wikipedia.org/wiki/Byrd_...dition_Medalhttps://www.omsa.org/files/jomsa_ar...20_10_19.pdfSince we know Captain Brown lived in Brooklyn, could the signature potentially be G.L. Brown, or possibly was A.J. Brown a relative of Captain Brown who happened to be at the Byrd first day ceremony in New York representing the dignitaries involved in the expedition?