brokered by U.S. Ambassador Dwight Whitney Morrow helps end the Cristero War in Mexico. June 27 – The first public demonstration of color TV is held, by H. E. Ives and his colleagues at Bell Telephone Laboratories in New York. The first images are a bouquet of roses and an American flag. A mechanical system is used to transmit 50-line color television images between New York and Washington. July July 24 The Kellogg–Briand Pact, renouncing war as an instrument of foreign policy, goes into effect (it was first signed in Paris on August 27, 1928, by most leading world powers). Union Airways Pty. Ltd. is founded, to be nationalised as South African Airways, on 1 February 1934. July 25 – Pope Pius XI emerges from the Apostolic Palace, and enters St. Peter's Square in a huge procession witnessed by about 250,000 persons, thus ending nearly 60 years of self-imposed status by the papacy as Prisoner in the Vatican. July 27 The Geneva Convention addresses the treatment of prisoners of war. The Red Crescent is adopted as an additional emblem of the League of Red Cross Societies. July 29 - the French prime minister Raymond Poincaré resigns, and is succeeded by Aristide Briand. August August 8–29 – German rigid airship LZ 127 Graf Zeppelin makes a circumnavigation of the Northern Hemisphere eastabout out of Lakehurst, New Jersey, including the first nonstop flight of any kind across the Pacific Ocean (Tokyo–Los Angeles). August 16 – The 1929 Palestine riots break out between Palestinians and Jews in Mandatory Palestine, and continue until the end of the month. In total, 133 Jews and 116 Palestinians are killed. August 20 – John Logie Baird's experimental 30-line television system is first transmitted, by the British Broadcasting Corporation. August 23–24 – The 1929 Hebron massacre: 65–68 Jews are killed by Palestinians and the remaining Jews are forced to leave Hebron. August 29 The 1929 Safed massacre: 18–20 Jews are killed in Safed by Palestinian Arabs. The collides with the oil tanker S.C.T. Dodd off the California coast, causing the San Juan to sink in 3 minutes, killing 77 people. August 31 – The Young Plan, which sets the total World War I reparations owed by Germany at US$26,350,000,000 to be paid over a period of 58½ years, is finalized. September September 3 – The Dow Jones Industrial Average peaks at 381.17, a height it would not reach