HAMMOND, JOHN HAYS (1855-1936). Mining engineer, called "America's greatest miner"; Financier. "No other figure in history ever added so much to mankind's supplies of gold and silver. Through his efforts mines in the United States, Africa, Mexico, South America, Central America, and Russia have added hundreds of millions of dollars [in 1916 dollars] to the world's wealth." (Men Who are Making America by B.C. Forbes). Hammond began his career in mining working for George Hearst in 1879 and soon thereafter began collecting statistics on gold mining for the United States Geological Survey, an experience which proved invaluable to his future. In the 1890s Hammond was hired by Cecil Rhodes to be his chief mining engineer of the Consolidated Gold Fields of South Africa, the company controlling the Rhodes interests on the Rand. It was Hammond who recommended Rhodes sell his outcropping mines and change to deep level development, a move which proved extremely successful. In 1896, Hammond was sentenced to death following the "Jameson Raid", resulting from the Transvaal mining interests belief that they were being treated unfairly by South African president Paul Kruger. Hammond was ultimately released after five months and a payment of $125,000.00. Upon returning to the United States in 1899, Hammond was the consulting engineer for a who's who of famous American mining and railroad financiers including: E. H. Harriman, William C. Whitney, the Guggenheims and Guggenheim Exploration Company and numerous others. He was active in recommending and securing many of the Guggenheim mining properties. He retired in 1907 due to poor health but continue many activities. Truly an important figure in mining and financial history, with the information merely providing a small sample of his activities. Card signed with sentiment. 5" x 3 1/4". "With my best wishes, John Hays Hammond, Washington D.C., Nov. 1923". Excellent.