Seismic reflection exploration grew out of the seismic refraction exploration method, which was used to find oil associated with salt domes. Ludger Mintrop, a German mine surveyor, devised a mechanical seismograph in 1914 that he successfully used to detect salt domes in Germany. He applied for a German patent in 1919 that was issued in 1926. In 1921 he founded the company Seismos, which was hired to conduct seismic exploration in Texas and Mexico, resulting in the first commercial discovery of oil using the refraction seismic method in 1924. The 1924 discovery of the Orchard salt dome in Texas led to a boom in seismic refraction exploration along the Gulf Coast, but by 1930 the method had led to the discovery of most of the shallow Louann Salt domes, and the refraction seismic method faded.