Transcribed from press release attached to back of photo: "PENETRATES EARTH 16,000 FEET A surface approaching the hardness of the diamond is applied by a new atomic-hydrogen welding process to the teeth of a rock bit drill at the Hughes Tool Company plant in Houston, Texas, owned by Howard Hughes, noted aircraft designer-flyer. The first Hughes rock bit revolutionized oil drilling practices in this nation several decades ago, making possible recovery of oil beneath hard rock formations at great depths. Most recent models have penetrated the earth below 16,000 feet. Hughes drills are used in 50 foreign countries. NOTE: The atomic-hydrogen process differs from other arc-welding processes in that the arc is formed between two electrodes, rather than one electrode and the work." The patent on the atomic-hydrogen process was awarded October 29, 1929.
39 x 62 cm. Relief shown by hachures and spot heights. Prime meridian: Greenwich and Washington. Hand colored. Shows natural features, populated places, routes of mail steamships, routes of explorers, locations of Indian tribes, railroad routes, and proposed railroad routes. In top margin: No. 80-81. On verso: New Mexico, Arizona, Colorado, Idaho, Dakota (statistics and other information) and The state of California (statistics and other information). Original publisher: G.W. and C.B. Colton.