A number of "Industrial Troops" to reach boys already out of school and employed. The Rural Scouting program was expanded with the Railroad Scouting program in 1926. The BSA began expanding the Negro Scouting program: by 1927 thirty-two communities in the south had "colored troops", with twenty-six troops in Louisville, Kentucky. The junior assistant Scoutmaster position was created in 1926 and Eagle Palms were added in 1927. "Boys' Life" promoted a photo safari to Africa for three Scouts in 1928. The three Scouts, Robert Douglas, David Martin, and Douglas Oliver, wrote the book "Three Boy Scouts in Africa" upon their return as part of their requirement of being selected for this trip with Martin and Osa Johnson, American photographers known for their African safari movies and photographs. Later in 1928, a trip to the Antarctic with Commander Byrd was promoted and Eagle Scout Paul Siple was selected for the expedition. Hillcourt wrote the first "Patrol Leader Handbook", published in 1929. The Silver Wolf was presented to Beard and Mortimer L. Schiff. The first Silver Buffalo Awards were presented in 1926. Membership registration and fees for volunteers began in 1929. By the end of the decade the BSA had a membership of 842,540.