www.nycsubway.org: Building New York's Subway (1903): Daylight was half a mile or more behind. In front a narrow arched passage, so low that the jagged roof just grazed one's head, followed a thin vista of hazy electric lamps farther into the solid rock. The heavy air was chilled with the breath of the under earth, and every now and then from under the tramway ties, or out of the indefinite darkness, came the drip-drip-drip and gurgle of water.
A thudding murmur in the distance suddenly grew more insistent and distinct. The shapes of men, of a swinging crane, of a tram-car mule, appeared under the flare of torches. The reverberations, locked between the narrow walls of rock, swelled into the deafening pounding of a steam-drill. Then a glimmer of daylight revealed the mouth of the shaft, and a moment later, clambering up into the open, I found myself in the lazy warmth of a summer afternoon and blinking at the velvet verdure of Central Park.