speed led to the use of a pilot tunnel at the heading. This consisted of a 5- foot iron tube, which was carried forward on the line of the axis of the tunnel into the material ahead. This tube was used as a center from which struts were carried out radially, to support the surrounding wall of the… … Street, the distance between the two shafts being about 5,400 feet. Mr. Haskin commenced the construction of the tun- nel without the use of the customary shield and iron lining, believing that the silt through which the tun- There was a blowout, which resulted in -such a sudden inrush of water,…
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