Engineering Wonders of the World
Volume I

.366 ENGINEERING WONDERS OF THE WORLD. carried from one office to another under- ground, they scouted the idea, saying that any such connection would undermine the building, cause a settlement, and probably result in its entire collapse. To prove that they were wrong, the engineer constructed a subway right under the centre of the structure. In places this tunnel had to go through the could not find a crack or a piece of plaster that had been disturbed. The post office still rests as solidly on its foundations as does the rock of Gibraltar. Not long after- wards the tunnel people secured the contract spoken of. For this mail work the railway employs 66 electric motors and 115 cars. In 1907 the MAIL BAGS BEING TRANSFERRED FROM THE CHICAGO POST OFFICE TO THE SUBWAY. BELT CONVEYOR DISCHARGING MAIL BAGS FROM SUBWAY ON TO PLATFORM AT THE UNITED STATES POST OFFICE, CHICAGO. piles on which the building rests, and the result is that the subway actually rests on the bottom por- tions of these piles, and the top parts of the piles on the crown of the tunnel. After this work had been completed, the engineer in- vited the postal officials to take a trip through the tunnels as his guests. They accepted the invita- tion, and one can imagine their sur- prise when the car was suddenly stopped, and they were informed that they were then right under the post office building. For two days, it is said, th© leading surveyors of Chicago were busy examining the edifice critically, but electric trains made 337.060 trips with mails through the subways to the various branch offices, railway stations, etc., transporting 10,659,567 bags, pouches, and packages of postal matter. The record for this tremen- dous service was “ 99'51 per cent, perfect”—that is to say, in this proportion of cases the mail was delivered at the proper stations in time. Last Christmas Eve the Com- pany handled, without a hitch, 44,341 bags of mails, 5,911 pouches, and 195 packages—a total of 50,447. In the construction of the tunnels the Company has burrowed under the river in fourteen places. Its lines now reach from Armour Avenue and Archer Avenue on the