Tunnels and tunneling

A tunnel is defined as a sub-terranean or sub-aqueous way, for purposes of passage. The term is also applied, in mining, to horizontal excavations, such as are commonly called drifts, headings, adits, etc., and used as underground roads, or passages for water or air. Tunneling, at the present day, has become of such importance, that it is in its-self a profession. The subject of Tunnels and Tunneling properly treated would require a large volume, but taking into consideration the time and space allotted to the preparation of this thesis, I shall be brief; and in order to treat it to the best advantage, I shall place it under the following heads = Historical and Descriptive; Explosives and Blasting; Drills and Drilling. The history of tunnels has been selected from the best authorities --page 3