The furnace was initially heated with mesquite and cottonwood. However, Perry hired geologist Johan August Udden to prospect for coal on his property in 1926. The resultant coal was used to generate producer gas. Water was supplied by Mexican freighters hauling water from the Rio Grande 12 miles away. Some water was also obtained from a dam built on the Terlingua Creek and was hauled 10 miles from springs discovered in the Christmas Mountains and Cigar Mountain. By the mid-1920s, water came from the 800-foot level of the Chisos mine, which was pumped to the surface. Udden was also responsible for discovering the great ore body located in the limestone under the Del Rio clay.: