Guidonian hand
In Medieval music, the Guidonian hand was a mnemonic device used to assist singers in learning to sight-sing. Some form of the device may have been used by Guido of Arezzo, a medieval music theorist who wrote a number of treatises, including one instructing singers in sightreading. The hand occurs in some manuscripts before Guido's time as a tool to find the semitone; it does not have the depicted form until the 12th century. Sigebertus Gemblacensis in 1105–10 did describe Guido using the joints of the hand to aid in teaching his hexachord. The Guidonian hand is closely linked with Guido's new ideas about how to learn music, including the use of hexachords, and the first known Western use of solfege.
Black Hand (Chicago)
One of the stories of assassination was told in the murder of Filippo Catalano, Catalano was in the Vesuvius restaurant a restaurant frequented by Chicago's night life. On the night of June 5, 1910 as Catalano walked out from the restaurant at approx. 3 a.m. in the company of Edgar K Accetta a New York Lawyer, who was in town on business, and a third man who was later identified as the person who shot Catalano, allegedly Eugeno Monaco an Italian man, the three men were walking towards an approaching car when Monaco allegedly drew a revolver and shot Catalano five times. In an incident involving Catalano on March 27, Catalano was alleged to have shot John Jocko in front of 1821 South State Street witnesses identified Catalano as the shooter, the victim survived the shooting and would not prosecute, at that time Catalano was released. Catalano's killer escaped fleeing on foot and was traced to the Rock Island Pacific Railroad tracks where he disappeared. Filippo Catalano fits in the time period where Johnny Torrio came to Chicago to assassinate Chicago Black Hand Gangsters who was extorting his Uncle from 1909 to 1911, by 1920 Black Hand activity had all but faded. Johnny Torrio then went on to run and organize The Chicago Outfit.