Hirschback method

Hirschback method

[′hərsh‚bak ‚meth·əd]
(mining engineering)
A method for draining firedamp from coal seams by means of superjacent entries located 80-138 feet (24-42 meters) above the seams and supplemented by boreholes drilled at right angles to the entry walls. Also known as superjacent roadway system.