Abstract: In a method and apparatus for lifting gas streams, vertical streams of air and/or gases of a great height are artificially formed in the atmosphere, mainly for decontamination purposes, by heating the air throughout a circular area sufficient to produce a shaft effect, so as to form an ascending column of air and/or gases. The air and/or gases are then driven within the column to produce a rotatory movement thereof to form a vortex. Once a column of a sufficient height has been formed, the rotatory driving action on the air and/or gases is interrupted while the heating thereof is maintained so that the vortex is maintained by the lifting force induced by heat.

Abstract: A method of excavating tunnels comprises digging an excavation to form a tunnel, gradually pushing a casing inwardly of the excavation as the excavation proceeds, the cross-sectional area of the excavation being larger than the outer cross-sectional area of the casing in order to provide a hollow annular chamber between the same; arranging at least a seal at the inner end of the casing to seal the annular section between said casing and the excavation; arranging a seal at the entrance of the excavation to seal the annular section between the casing and the entrance to the excavation; and injecting under pressure a drilling mud to completely fill the annular space between the casing and the excavation as the excavation front advances, in order to provide a fluid support for the walls of the excavation and to float the casing within the excavation, whereby friction contact between said casing and the excavation is prevented as the casing is pushed inwardly of the excavation.