8/18/2009:
In August of 1932, the home of Dr. J.A. Prescott was filled with eager visitors who came to witness the demonstration of a revolutionary new machine. After more than ten years of experimentation, Dr. Prescott successfully completed a machine-operated placer mining device called a "gamco." On this date in 1932, the Stutsman County Record announced the successful test of Prescott's invention, which flawlessly separated gold dust from sediment.
Dr. Prescott was the bandmaster of Jamestown College-an unlikely inventor who pursued his passion on the side. His crude invention made of old parts from automobiles, farm equipment, and a soda fountain must have looked truly bizarre to the spectators. But in spite of its odd appearance, the gamco worked wonders. The main body of the machine consisted of three ten-inch revolving pans with silver-plated bottoms. When gold-rich sediment was added to the machine, the dirt and sand was forced from one pan to the next and washed away with water. A small amount of liquid mercury-a substance which aids the extraction of loose gold from dirt-was automatically added to each pan as well. When the process was complete, pure gold lay in the bottom of the pans.
When compared to the old mining methods of sluicing and panning, the efficiency of Prescott's machine was astounding. During gold rushes like those in California, most gold was not found beneath the ground in mines, but above ground mixed in with sediment. To separate the "placer" gold from the undesirable dirt, prospectors either sifted through the piles one pan at a time or built large wooden troughs called sluices into natural sources of running water like creeks and streams. In sluicing, gold-rich sediment was poured into the boxes, and the flowing water swept away the dirt, leaving the heavier gold bits the bottom of the box. However, this method required massive amounts of water and polluted clear streams with silt. Also, mercury that was added during the process often leaked from the troughs.
However, Prescott's gamco eliminated most of the pollution caused by placer mining. The machine used small amounts of water that were recycled throughout the operation, and no mercury was lost during its mining process. Old fashioned panning was no match for the gamco either, as the machine could produce as much gold in one day as it took 100 men to pan. Prescott's mining machine was a triumph, and not long after its successful test, the gamco was sent to Long Beach California where Prescott hoped it would be reproduced and used in abandoned placer mines throughout the state.
Dakota Datebook written by Carol Wilson
Sources
http://www.britannica.com/EBchecked/topic/462603/placer-mining
Steele Ozone and Kidder County Farmers Press, August 11, 1932.
Stutsman County Record, August 18, 1932.
www.ca.water.usgs.gov/mercury/fs06100.html