THE NATIONAL GEOGRAPHIC MAGAZINE 



37 



The chemical causes the clay to coagulate 

 and settle to the bottom of the reservoir 

 while waiting its turn to pass into the 

 city-bound watermains. 



WHERE The water is "gassed" 



At the outlet of the Kensico Reservoir 

 there is a chlorination plant. Here the 

 Water Department practices the German 

 art of "gassing" on the germ tribe. A 

 very small quantity of this gas will kill 

 many millions of germs. Nowhere else 

 in the world, except on the battle front, 

 is "gassing" practiced as much as in the 

 battle against the disease germ armies 

 that seek to invade New York via its 

 water supply. 



After leaving Kensico Reservoir, the 

 Catskill Aqueduct flows another 17 miles 

 to Hill View Reservoir, used for equal- 

 izing day and night consumption of water. 

 This brings the water to the metropolis, 

 where the great 18-mile tunnel through 

 solid rock under the city begins. This 

 tunnel is the longest of its size in the 

 world. 



Starting at Hill View Reservoir it is 

 15 feet in diameter through Harlem and 

 under Harlem River to 135th street. It 

 is within three inches of being as large 

 in diameter as the Hudson Terminal 

 tunnels under North River. It crosses 

 the Harlem between High Bridge and the 

 Polo Grounds and extends through Cen- 

 tral Park and Madison Square to a point 

 between Williamsburg and Manhattan 

 bridges, where it dives under East River. 

 On the Manhattan bank of the river there 

 is a shaft in which the Woolworth Build- 

 ing could be buried, so far as depth is 

 concerned. 



HEEDLESS OE HUMAN MOLES BLASTING 

 THEIR WAY BENEATH THE CITY 



After passing under the river the tunnel 

 rises to the surface in Flatbush, where it 

 connects with the 5-foot-6-inch Brooklyn 

 main. Hence its water runs on to the 

 Narrows, where a three-foot ball-and- 

 socket pipe-line, with joints calked with 

 300 pounds of lead, was laid in a trench 

 cut in the floor of the inlet. This line 

 carries the water to Staten Island and 

 into Silver Take Reservoir, 119 miles 

 from the intake at Ashokan. 



Here we find how much an uncon- 



sidered thing in every-day experience may 

 count in a big project. Take a U-tube and 

 put water into it. The water rises to the 

 same level in both sides. But, although 

 Ashokan and Silver Lake are the two 

 terminals of the figurative Catskill U- 

 tube, their waters by no means reach the 

 same level. The surface of Silver Lake 

 is 362 feet lower than that of Ashokan 

 Reservoir, because of the friction in the 

 big waterway. When it is remembered 

 that a column of water 362 feet high 

 exerts a pressure of more than a thou- 

 sand tons per square foot, one can ap- 

 preciate the amount of friction the water 

 encounters in its journey to the city. 



Although, on an average, five tons of 

 dynamite were exploded daily during the 

 long period in which the city tunnel was 

 being built, New York might never have 

 known that rock-defying human moles 

 were boring their way through the big 

 town, from the Yonkers line to Flatbush, 

 except for the shafts sunk from the sur- 

 face at convenient spots. 



URBAN TRANSPORTATION 



As a completed project, the Catskill 

 Aqueduct stands as one of the wonders 

 of the engineering world. With a length 

 of 119 miles, with a capacity that exceeds 

 the combined flow of all the aqueducts 

 that imperial Rome ever built, with 35 

 miles of tunnel sunk deep in the primeval 

 rock, the great subterranean stream that 

 brings the life-giving, health-protecting, 

 industry-quickening waters of the moun- 

 tains to the people at the gateway to the 

 seas represents the indomitable spirit of 

 a municipality that is as virile as it is big, 

 ready to shoulder any burden its unceas- 

 ing growth imposes upon it. 



In no other phase of its complex life 

 has New York felt so acutely the prob- 

 lems that its size and peculiar geographic 

 situation involve as in the matter of ur- 

 ban transportation. With its own popu- 

 lation supplemented by the army of com- 

 muters living in Jersey, on Long Island, 

 and up the Hudson, twice as many people 

 are transported in a single day within the 

 confines of Greater Gotham as are moved 

 by all the steam railroads of the United 

 States. 



Go to Grand Central Station during 

 the rush hours of the morning and after- 



