for trumpet. Extreme preparations involve alternate constructions, such as double bells and extra valves. Split tone: Trumpeters can produce more than one tone simultaneously by vibrating the two lips at different speeds. The interval produced is usually an octave or a fifth. Lip-trill or shake: Also known as "lip-slurs". By rapidly varying air speed, but not changing the depressed valves, the pitch can vary quickly between adjacent harmonic partials. Shakes and lip-trills can vary in speed, and in the distance between the partials. However, lip-trills and shakes usually involve the next partial up from the written note. Multi-phonics: Playing a note and "humming" a different note simultaneously. For example, sustaining a middle C and humming a major 3rd "E" at the same time. Circular breathing: A technique wind players use to produce uninterrupted tone, without pauses for breaths. The player puffs up the cheeks, storing air, then breathes in rapidly through the nose while using the cheeks to continue pushing air outwards. Instruction and method books One trumpet method is Jean-Baptiste Arban's Complete Conservatory Method for Trumpet (Cornet). Other well-known method books include Technical Studies by Herbert L. Clarke, Grand Method by Louis Saint-Jacome, Daily Drills and Technical Studies by Max Schlossberg, and methods by Ernest S. Williams, Claude Gordon, Charles Colin, James Stamp, and Louis Davidson. A common method book for beginners is the Walter Beeler's Method for the Cornet, and there have been several instruction books written by virtuoso Allen Vizzutti. Merri Franquin wrote a Complete Method for Modern Trumpet, which fell into obscurity for much of the twentieth century until public endorsements by Maurice André revived interest in this work. Players In early jazz, Louis Armstrong was well known for his virtuosity and his improvisations on the Hot Five and Hot Seven recordings, and his switch from cornet to trumpet is often cited as heralding the trumpet's dominance over the cornet in jazz. Dizzy Gillespie was a gifted improviser with an extremely high (but musical) range, building on the style of Roy Eldridge but adding new layers of harmonic complexity. Gillespie had an enormous impact on virtually every subsequent trumpeter, both by the example of his playing and as a mentor to younger musicians. Miles Davis is widely considered one of the most influential musicians of the 20th century—his style was distinctive and widely imitated. Davis' phrasing and sense of space in his solos have been models