Rhythm Grid by Thomas Parker WilliamsThe numbers 1,2,3 and 4 were arranged in a grid with the vertical columns designated a,b,c and d. The seven formulas, in the chart next to the grid, were used to create the seven percussion parts in the Electronic Drum Kit and the Acoustic Drum Set using the numerical values of the horizontal rows corresponding to the letters of the vertical columns. These formulas were used four times to create the four measures shown in the musical transcription.