The longer bells create low pitches, while the shorter bells create higher pitches in the scale. When a handle on the wall of the subway platform is pulled, teak-headed hammers swing back and forth between the bells, striking them and creating the musical notes. Due to asymmetrical slits located at the nodal points in the bells, each chime's note plays a slight vibrato. There are actually two identical, completely separate and independent musical instruments comprising Pythagoras. One can be operated from a handle located on the inbound subway platform, and the other can be played simultaneously from a handle on the outbound side. The hammers are not directly coupled to the handles, to prevent them from striking the chimes too violently. Instead, the handles must be rhythmically moved back and forth at an appropriate frequency, depending on the physical phenomenon of mechanical resonance to build up enough energy to strike the chimes. Which chimes are sounded when depends in a complex manner on the recent history of handle movement. Although the detailed mathematical analysis of motions is quite complex, most visitors quickly and intuitively figure out how to operate the sculpture without any written instructions. The "Kepler" section is named for Johannes Kepler, a 17th-century German mathematician, astronomer and astrologer. This instrument features a 125-pound, 55-inch, metal ring that plays an F♯ when struck. This note creates a harmonic perfect fifth with the tones sounded by "Pythagoras". The ring plays this note when a handle on either subway platform is manipulated, which in turn ratchets a hammer upward until it falls and strikes the ring. After the ring is struck, it will continue to hum for five minutes. The "Galileo" instrument is a large metal sheet the size of a barn door, and is named for Italian physicist, mathematician, astronomer, and philosopher Galileo Galilei. The flat panel of steel works like a thunder sheet. When a handle on either station platform is moved, the sheet shakes and creates a low rumbling sound, similar to the sound of thunder, or the sound trains make when rolling through the station. Paul Matisse was the only artist commissioned for the initial "Arts on the Line" program who created an artwork with moving parts. Almost immediately after the "Kendall Band" was installed, it broke. The sculpture began to fail so quickly that the Pythagoras instrument stopped working before the other two could even be completely installed. Matisse later commented that, "You’d probably have to say it was folly of me to press ahead and present them with something that had moving parts...(but)...I figured it was going to be all right."