The Montgomery advertiser., 1906-09-02

fr I but the majority of the workers are il
 the anskillod class---the men who pu I In place the iron plates that form tn tubes. Each plate weighs ton O
 more, and eleven of them with key l piece form complete ring of iron r. I feet wide. Hydraulic erectors lift th' I Iron Into place, and hold 1t while | l is boited to the ring that has gone he. I fore: hydraulic rams braced against tns newest ring force the shield forware l another ring, This Is the routine o1 the tunrel worker. The record is fiv, | rings 12 1-2 feet--in eight hours. But the danger of the work? Dan, I gers there are. or certain risk oi I injury, but not enough to worry any man in good health who will observe the rules that stare him in the face I from every wall.
 For to make it as safe under the bed \ of river as 1t is on the lands sur l face is the aim of the Pennsylvania i tunnel builders. The old Hudson Iiv- CT tunnel. which crosses the Hudson at Morton Street, was abandoned at one time because so many lives were lost The main difficulty was to keep the river from coming into the tube and drowning the workmen. The air under the heavy pressure required to keep the water from sweeping in, sometimes Flew the roof off the tunnel altogether and then the water poured in in such volume that there was lit- tie or no time for escape.
 Emergency Curtain for "Bi0w Outs.S
 But nowadays the life of the sand
 hog" is at least as safe as that of the surface worker. Except at times,
 when 1t is necessary to send few men
 out back of the shield, the workers are
 protected by the massive rings of iron
 which form the tube, and in front is
 the still more massive shield. Stfli
 there remains the possibility that the
 water will break in and so wherever
 this disaster is at all likely to occur, steel emergency curtains surrounding
 an air lock. are dropped from the roof
 of the tunnel They reach from tne
 roof to point just above the centre, and the emergency gangway running
 from the heading of the tunnel to. the curtain makes this isle of safety svail- able at all times. The theory of the curtain is the same as that of the div
 ing bell Once the men get behind It they know that the water will not rise above the edge of the curtain, and so while they may be wet to the waist, they will always have breathing space
 Recently in one of thsrEast River tunnels pocket of wet sand suddenly dropped upon the back of the shield. and, given this avenue of escape. the air at pressure of thirty-four pounds
 to the inch, burst through the bed Of the river. Within few minutes tire tunnel was flooded to a depth of sew enteen feet, but all the workers except
 two wedged each other in one of the shield compartments, made their cs. cape without difficultv to the emergen- cy curtain.
 There remains the fact that hard work under high air pressure produces
 inside the workers a danger that IS perhaps more to be feared than the dangers from without. Medical men are still disputing over the exact na- ture of ''caisson disease, or the bends" Some of them say that the disease is nothing more than bubbles of air in the veins or arteries--more air than the blood can absorb. Others say that the bends" Is congestion or blood produced by coming out of high pressure too quickly. What every body admits Is that the bends is disease not to be trtfled with, although 1t is by no means necessarily fatal On the contrary, the medical staffs of the Pennsylvania tunnel builders now have such thorough knowledge of the disease and such excellent facilities for treating it, that not man has been lost on the North River tunnels, and very few on the East River--nOhS IT recent months
 What complicates the difficulty of safeguarding the tunnel worker is chat a man to labor with absolute safety in compressed air should not use liq- or or tobacco excessively. There are only a small number who can be in- duced to give up drinking while they are working in compressed aire. Anoth- CT trouble that the tunnel builders have to deal with is that workmen, unless they are very carefully watched, will not obey the rules made for their safe ty,
 The most important of these rules Is one that requires the men to come slow ly through the air locks The rule is to take a minute for about two pounds of pressure; in other words, in coming out of a pressure of thirty-four pouads a man should spend not less than fif- teen minutes In the lock. Finding that this rule was ignored, Henry Japp. managing engineer of the contractors who are building the East River tubes. has devised valve which enables the lock tender to regulate the change Of pressure with mechanical exaetness.
 The "ReeOmpresalOn" Care.
 But notwithstanding all the precau- tions taken to safeguard the men, tll- ness now and then develops, and through provision is made for the care of workers on the sick list The most the patient into an air loc'l, raise the pressure as high as that L..der which he has been working, a.ll then reduce it very gradually. The medical air lock is part of the office equipment of the medical staffs which are main tained on both sides of North and East Rivers wherever any subaqueous work is going on.
 Before a man Is permitted to work in the under river tunnels, he is put through severe exan1tlJtton for heart and lung troubles and general condi- tion. If he passes the medical inspec- tors he is sent down in he ali" for an hour or two, and then re-eXaEalned If the second examinations !@ catistac- torily passed he is put on short shift for a week, and than |, te shows no Ill effects is given a steady job.
 Coffee is the mainstay of the tunnel worker. and 1t is to he had a all times and at all places. EveFy tunnel Is eqipped with a coffee machine and the hot beverage Is on tap at all hours oi the day and night without enlarge Science Searching for More Knowledge.
 Although the Pennsylvania tunnel builders believe that they now have all means for protecting the lives and the health of their workers, investigation is constantly going on to find out If there Is anything more that could be | done to reduce the dangers of cais- son work Pearson and Son, who hold l the East River contract and have by l far the most difficult part of the work | to be performed, have employed Eng l fish scientists to make an exhaustive | study of the effect of air pressure, with | a view to suggesting methods of avoid- | ing caisson disease altogether.
 Two of these scientists recently spent | three hours under a pressure of nine | ty-two pounds without any apparent | effect. except that if they held an arm | or leg in one position 1t became stiff. |