In addition, these laws present a compositional process similar to serialism. He also wrote Pre-Sonido 13: Rectificación básica al sistema musical clásico—Análisis físico musical (Pre-Thirteenth Sound: Essential Rectification to classical musical system—Physical musical analysis) and Teoría lógica de la música (Logical Theory of Music). When he came back to Mexico, State of San Luis Potosí's government honored him for the Thirteenth Sound. It declared July 13 (anniversary of the 1895 experiment) as State Day of Honor. The National Flag was raised over Carrillo's house from 6 am to 6 pm. Despite governmental recognition, Carrillo didn't receive economic support for his musical revolution. Opponents put obstacles to his working as a conductor and professor of music. After that, he rarely was invited to conduct in Mexico and his music seldom performed. The former Principal of the National Musical Conservatory and titular Conductor of the National Symphony never obtained similar jobs again, in spite of his abilities and experience. He had to pay for his own musical research, making musical instruments, publishing his compositions, et cetera. In 1930, Carrillo organized the Thirteenth Sound Symphony Orchestra, in which all the musical instruments could perform microtones. From 1930 to 1931 Carrillo and Leopold Stokowski conducted this orchestra. In New York City on February 7, 1930, Ángel Reyes, principal of the Thirteenth Sound Group of Havana, recorded the Preludio a Colón (Prelude to Christopher Columbus) for the Columbia label. That year, the town of Ahualulco was officially renamed Ahualulco del Sonido 13. In 1934, Carrillo published La revolución musical del Sonido 13 (The Thirteenth Sound Musical Revolution), which gave the historical background of his revolution. In 1940 he published another book, Génesis de la Revolución Musical del Sonido 13 (Genesis of the Thirteenth-Sound Musical Revolution). Pianos and metamorphosis In 1940, Carrillo patented fifteen metamorphoser pianos for producing whole tones, third-tones, quarter-tones, fifth-, sixth-, seventh-, eighth-, ninth-, tenth-, eleventh-, twelfth-, thirteenth- fourteenth-, fifteenth-, and sixteenth-tones. Each piano produced one set of intervals but all of these pianos have sets of 96 keys unlike common pianos. The piano with quarter-tones could produce four full octaves and the piano with sixteenth-tones only one. In contrast, Wyshnegradsky's piano for quarter-tones has three sets of 88 keys. In 1941 Carrillo published Método racional de solfeo (Rational method of solfeggio). Its guiding idea is that a person has to proceed from known things to discover new things. So his exercises for