Show A Ticklish Bit of Tun Tunneling A A very Int Interesting bit of tunneling was rec recently done on the Fourteenth street tube under the East river New York The heading was being run in rock and at one point test holes showed showed show ed a av a thickness of only eight Inches of sound dry rock above the li line e along which the top of the tunnel was to run As the tunnel was being driven without the the- use of ot compressed air ir it was VaS decide l to drop the upper headIng head head- Ing tag four feet until this thin cover of rock was passed The Tha The cast cast iron lIning was set in place at each at-each each side of this section and aid the rock was removed very carefully by using a great many holes each loaded with about one- one eighth of a stick of dynamite As each bit of rock was ws removed the arch of th the h tunnel lining was set In place By this means the n was vu t tunneled without br breaking g through I Ithe the the thin shell |