332 



busy for a while, discharging a volume 

 of water as great as the daily supply 

 required for a city the size of Atlanta. 

 Care had to be taken, meanwhile, not to 

 pump out sand along with the water, or 

 the adjacent buildings would have come 

 tumbling down, just as in a certain en- 

 gineer's vision of the most effective way 

 of destroying the city of Boston: 



"An e n e m y need not 

 bother mustering battleships 

 or waste his time bombard- 

 ing from afar the intellec- 

 tual Hub of this land of 

 ours. In time of peace let him 

 have his spies build a big 

 pumping station right in the 

 middle of that city, and at 

 the proper time start draw- 

 ing indiscriminately from 

 the ground below the water 

 saturating the subsoil. You 

 know a large number of 

 Boston's big buildings rest 

 upon floating foundations. 

 Pmnp out the water in the 

 supporting quicksand, and 

 down those structures would 

 t u m b 1 e into the yawning 

 cavities so created. It would 

 be far more effective in its 

 demolition than the projec- 

 tiles of a hostile fleet !" 



Up near the north end of 

 Manhattan Island, at Lex- 

 ington Avenue and One 

 hundred and Twenty-ninth 

 Street, the subway diggers 

 had to construct another 

 stout waterproof floor when 

 they encountered what evi- 

 dently was once a swamp. 



We mentioned, in passing. 

 the razing of the old Astor 

 Flouse, which was built upon 

 sand. The tunnel which 

 comes up Vesey Street and 

 cuts under the site of the 

 old hotel curves around into 

 Broadway through big cylin- 

 ders of cast iron. 



Underground swamps and 

 watercourses, sand, quick- 

 sand, sand mixed with boul- 

 ders (as in Brooklyn) — all 

 these the diggers encounter 

 and vanquish. But what the 



Popular Science Monthly 



subway builders fear most is something 

 dift'erent from all of these: a material 

 known to the geologist as Manhattan 

 Schist and to the rest of us as "rotten 

 rock." No material is more treacherous 

 than this, for along' with layers of ex- 

 treme hardness are pockets and seams 

 of disintegrated stuff", some of it so soft 

 that, after it has been exposed a little 



Under the old Astor House, which has been torn down 

 because an underground swamp made it extremely 

 hazardous to tunnel beneath the building. The illus- 

 tration shows an underground dinner of celebration 

 when a section of the iron tubes for one of the subway 

 lines was completed. The arch of the big tubes shows 

 in back of the posts at the left of the picture 



