The Montgomery advertiser., 1906-12-09

1 ing through its sides. Into this cham be was pumped compressed air. which alao served to keep out the water. As
 the men inside dug away the earth the i chamber sank steadily towards rock bottom, forced down by the. ever in- | cFeasing weight of the great concrete
 column which was being nodded on | top of it. Through the center of this | column ran a cylindrical steel shaft about three feet in diameter, This shaft gave the workmen access to the graduallSS sinking chamber. and also | served as passage for removing the cxcavated material. ,t
 When at last the working chamber had reached the solid rock. 1t was filled with concrete, the sand hogs" working up as before they had worked down, and the termination of their task left completed shaft of a ma terial as solid as rock and capable of bearing ap enormous weight. The av- craze depth of one of these caissons In Manhattan is from seventy-five to eighty feet below the water level, and as result most of the work of ex- cayation must be done under a con siderable air pressure. Mdch has been
 written about the herolsm of the men who bore tunnels under river beds or ] sink caissons to support massive | bridges, but the sand hog" in the building trade shows nerve equally as great and runs equally as great risk considerably more, in fact, than the av- craze citizen would care to take in | earning a living. The trade of the sand hog" has | grown to such importance that it's | members are bound together by a un- ion, which has drawn up, with expe- l rience as a basis, set of rules the
 most important of which regulates the | T .f nrlr nm der various degrees of air pressure l The normal pressure Of the atmos- phere is approximately sixteen pounds I to the square inch. In caisson sink I ing the pressure is artifieially in- | creased one-half pound to every foot added to the depth of the excavation. | In ratio to the pressure, the strain on while the sand hogs" may work for eight hours under no more thHn twen- | ty pounds pressure, when the pres- sure rises as high as twenty-five, four | shifts of men work in every twenty ] four hours. and the working periods
 decrease with the increasing pressure | until fifty pounds Is reached. which | is the limit beyond which no man could work with safety
 l The immediate welfare of the sand hog" IS guarded by q lad who sits just outside the caisson with his eyes | glued for hours at time on an air gauge, on the dial of which is regis | tered the slightest fluctuation of the l pressure inside. It is hls business, by
 means of valves, to keep the pressure
 steady and to notice and give warnings of any unusual conditions
 Inside the caisson. the heat is so | great that it would be uncomfortable l for men not hardened to the work. The sand hog,' in shifts of four, ufa- aF | into the earth hour after hour, day after day, in an atmosphere in which | hot moisture drips from the walls and an occasional draft of cooler air fills blfnding steam. Like gnomes, stripped to the waist, they dig on stolidlyi with | apparently no thought of their de- | pendence on the lad outside, or upon 1 inc timbers of the chamber which 1 might give way under some unex- f pected pressure and bring about a I wild scramble up the caisson smart
 in a mad race with the inrushing water.
 Many caissons must be sunk to sup l port a single buildings But the work
 has been so systematized and sate-
 guarded that the foundation company
 which, in addition to sinking the caissons for the Trust Company of Americas new buildings was engaged l at the same time in a number or oth- | or foundation problems. III LhS SlCS' reports but two fatalities within the last six years, both of which occurred
 to men engaged on work preliminary | to the actual caisson sinking. The occupation is one which seems to have | A fascination for the sand hogs. Otherwise it would be hard to explain a mans return to such a job after an
 accident like that which befeh the
 workman who. when engaged in the | EtlnnelinE work under the Hudson RiV- CT. was blown through number or feet of river bed and then up through the water into the air above. He was nicked up by some boatmen and has since been holding the position Of foreman in a shift of sand hogs at
 work sinking caissons on lower Broadway. ...
 When the first of the Wall street slxyscrapers is completed, the work which has been done during the past wear will be largely hidden from sight 1 but it is the process of sinking the great concrete shafts which makes 1t Possible to pile story on story, and 1 in the case of an institution like the | Trust Company of America, the water tipht fortresslike basement becomes a nlace where millions may be Kept
 without danger that thieves will break through and steal or that moth ana