Cepheid Variable Star
Oct 5 Edwin Hubble identifies Cepheid variable star
- Oct 6 1st NL unassisted triple play (Ernie Padgett, Braves against Phillies)
- Oct 6 US Lt Al Williams fly 392.2 KPH (record)
- Oct 6 USSR adopts experimental calendar
- Oct 7 Yankees Everett Scott runs his consecutive-game streak to 1,138
- Oct 10 NY Giants & NY Yankees become first teams to play each other in 3 consecutive Baseball World Series; Giants win Game 1, 5-4; first WS game played at Yankee Stadium
- Oct 10 Saxony gets Social Democratic & Communist coalition government
- Oct 11 A pair of Babe Ruth home runs in the 4th and 5th innings is the difference; NY Yankees beat NY Giants, 4-2 at the Polo Grounds to tie World Series, 1-1
- Oct 11 German Mark falls to 10 billion per £, 4 billion per $
- Oct 13 Angora (Ankara) becomes Turkey's capital
- Oct 15 American pianist Henry Cowell sparks a riot among audience members at Gewandhaus concert hall in Leipzig, Germany - some tried to physically stop his avant-garde performance, while others defended him
- Oct 15 Baseball World Series: NY Yankees beat NY Giants, 6-4 in Game 6 at the Polo Grounds for a 4-2 series win; Yankees first World Series victory
German Hyperinflation
Oct 15 Hans Luther presents a plan for currency reform to stabilize the German Mark during hyperinflation.
AL Prohibits Boxing
Oct 19 Ban Johnson persuades AL owners to prohibit boxing in their parks
- Oct 19 Beierse government refuses to prohibit NSDAP newspaper Völkischer Beobachter
Teapot Dome Scandal
Oct 25 Senate committee publishes 1st report on Teapot Dome scandal
- Oct 26 Dutch Government of Ruijs de Beerenbrouck resigns
- Oct 26 Dutch second Chamber rejects Fleet laws (50-49 vote)
- Oct 29 Army move SPD/KPD-government to German part of Saxony
- Oct 29 Gibbs, Grey and Wood's revue "Runnin' Wild" (introducing "The Charleston") opens on Broadway, New York City
- Oct 29 Kemal Atatürk declares Turkey a republic (successor state to Ottoman Empire)
- Oct 29 Mustafa Kemal officially confirms Turkey as a republic (Türkiye Cumhuriyeti), now commemorated annually as the Republic Day of Turkey
- Oct 29 Textile strike against lower wages begins in Enschede, Netherlands
- Oct 31 160 consecutive days of 100 degrees F begin at Marble Bar, Australia