Zoeppritz was not the first to mathematically describe this phenomenon as the British seismologist Cargill Gilston Knott used a different approach to derive Knott 's equations in 1899 .
This was still unknown in Germany by the 1920s .
Zoeppritz was not the first to mathematically describe this phenomenon as the British seismologist Cargill Gilston Knott used a different approach to derive Knott 's equations in 1899 , but this was still unknown in Germany by the 1920s .