The daily morning journal and courier., 1902-01-25


 rails piled on in overhanging crossed
 layers.
 One of the most important, interesting
 and remarkable engineering feats on
 this continent was the construction of the Chicago drainage canal canal
 twenty -eight miles long, dug at an eX- pense of over $50,000000, 1t taps the Chicago River some distance above its i mouth and causes it's foul waters mix
 ed with large quantity drawn from
 the lake, to flow short distance up
 stream and then through the canal into
 the Desplaines River, and thence to the Gulf of Mexico.
 The canal is cut to a depth of twenty
 two feet below the water level. and for | several miles through the prairie is
 nearly 300 feet wide on top and required i the excavation of over 2S0,000000 cubic
 yards of earth, which had to be dug
 up, lifted out and piled in great hills, 1 often hundreds of feet away from the edge of the canal bank.
 As the average price paid for excavat-
 ing, lifting and removing the earth was
 about one cent cubic foot, only frac- 1 tion of what is usually paid for ordin- i ary quantities of excavation, the con- ] tractors were obliged to invent cheap
 methods, and the great principle of sue
 cess was found to be in handling the earth in large quanties and keeping 1t continuously moving.
 Most of it was dug by steam shoVels working in the bottom of the trench, which could scoop up a wagon load at once, and do it on an average of once minute of oftener all day long. In one place the steam shovel worked back and forth across the canal, cutting 8 section ten feet wide and fourteen feet deep at each trip
 Each bucketful of ton or more of hard sticky clay was dumped by the shovel into the hopper of a grinding machine, which delivered it on top of an endless, wide rubber belt extended across the bottom of the canal
 A second belt reached up to the top of the slope and in turn Qverlapped the end of a third, which was carried along the floor of a 200-foot bridge elevated 90 feet above the ground on rolling towers at each end Each of the three belts was supported on rollers hollowed lit- tie in the center, like dice boxes, which made it sufficiently concave to retain the clay, like a trough.
 They were driven at a speed of about seven feet a second and ceaselessly car ried the clay away from the shovel, up the canal slope, on top of the bridge and over it to a variable point, where a diagonal scraper was set across it, and pushed the load off, to fall through the bridge floor and pile up on the ground underneath.
 When the steam shovel completed a cut across the canal, which perhaps re- quired two days, it's track the belts and the bridge were all moved ten feet ahead, and the process was kept up Many of the chunks of clay were as large as a mans head, and it was amusing to watch them ride quietly along until they began the as- cent of the steep bank, and then begin to roll and tumble and start down with an evident determination not to go up that slope under any circumstances.
 They would hurry and scramble as fast as possible, but it was not steep enough for them to fall quite as fast as the belt travelled, and it would keep picking them up again and again, each time lifting them a little higher before they would succeed in starting down, until at last they were landed on the evel belt on top.
 Blasting tunnel through the solid 'ock is usually considered an easy and l comparatively safe task eXcavating t in solid clay with a god depth of the same material overhead is sometimes still easier. Even quicksand may be oireced at the expense of sufficient time md money, but when it is necessary to tunnel through soft mud and silt very , lear the river bottom in deep water he task is one of the most difficult dangerous and costly that can be at empted. Such a tunnel with an inside diameter 1 f ten feet was recently built in a very novel manner. A high concrete tube, 25 feet long, lined inside and covered { outside with steel plates. was built on hore on regular inclined ways. ! The ends being closed, the 1,000-ten ( mass was launched like a ship lowed hirty miles to place, sunk between ows of guide piles driven on both sides if it, and one end connected by divers ' O the shore tunnel previously built to ( oin it. The most remarkable feature f the work was that a storm arose 7 nd threatened to injure the floating unnel before it was quite completed. l Large valves were hastily opened and { was allowed to fill and sink to a depth [ elow the storm action. When t was J alm again the water was pumped out nd the great pipe rose to the surface, yas completed, and again sunk this f ime permanently seating itself on the 0undation of piles cut off accurately V submerged steam saws at the re- uired level, far below the surface of , he river. - In sinking deep shafts through quick and it is often impossible to keep out x le water so men can work in the bot ln The sides will cave in continuous /, quicksand will enter like water : trough the smallest creVice in the lin- lg and tons of it will flow through a ,ng distance underground. so as to ause depressions in the surface at re- 4 lote places. Worst of all, the sand and water will SC up in the bottom as fast as it can Q pumped out and this added to the reat pressure on the sides and the diff culty of building a Watertight lining ( 'om the top down, makes the work ow and difficult Recently the eXpedient of freezing the