 Complete the following phrase:  In 1859, Koenig both published his first catalog, and inverted the phonograph which would play a crucial role for the graphical analysis of sound. By inverting the phonograph, Rudolph made it easier to record and store sounds made by the vibrations of air particles. Around 1860, along with Hermann von Helmholtz, Rudolph Koenig worked to devise an electronically controlled sound. After working alongside him, Koenig became the main maker and seller of Helmholtzs instruments. Two years following this in 1862, he began to exhibit the o-metric flame apparatus see attached image and description for more information at the 