This class provides for (a) the obtaining of valuable, naturally occurring minerals from the earth in a solid state (the phrase "solid state" including a state in which the minerals are in the form of particles of larger size than colloidal), (b) the obtaining of ice from a naturally occurring bed of ice, (c) the obtaining of naturally occurring, nonhydrocarbon, solid, valuable, minerals from the earth in a fluid state (the phrase "fluid state" including a dissolved state or a state of colloidal dispersion or suspension) or (d) the obtaining of any naturally occurring valuable material from the earth in a solid or fluid state when this is accomplished by the claimed use of a substantially horizontal tunnel providing a working space for human beings.
This class also provides for cutting, severing or breaking up of naturally occurring solid, hard material. Such cutting, severing or breaking up of solid, hard material generally comprises, (a) recovering valuable material in desirable shapes or specific sized chunks, (b) forming an opening or cut in native material of larger cross-sectional surface area than the effective cutting area of the cutting means by movement of the means parallel to the exposed surface, or (c) forming a large horizontal passageway into the earth by continuously advancing a cutting device by means of a vehicle or the like which is limited to substantially horizontal operation, the cutting means forming the entire passageway in an uninterrupted advance movement as the vehicle or the like follows the cutting means into and along the passageway.
This class further includes miscellaneous subject matter which does not meet the criteria of the above, but which relates to forming or using a large underground passageway in the earth and is not elsewhere classifiable.
This class was partially formed from an unofficial classification that had been used by the Examiners for many years. While the schedule and definitions are intended to be employed as completely consistent with present rules of classification, the claims of the patents at the time of the formation of this class have not been analyzed to the degree necessary to guarantee exact technical, original or cross-reference classification of all patents.