"Research and experiments at the largest plants devoted to underground gasification of coal in the USSR indicate that underground generators will be a very good source of gas. Recently, mining has become an area in which there has been a great deal of mechanization and many of the methods of mining that were difficult, dangerous, and harsh have been replaced. This accounts for the great advantage of underground gasification by the percolation method, in which underground work will be completely replaced by trained work on the surface, with resultant utilization of complex mechanization and automation."