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“all Safe, Gentlemen, All Safe!”
The ups and downs of the invention that forever altered the American skyline
August/September 1978 | Volume 29, Issue 5
Ten stories was about the limit for an office building put up in the traditional way, that is, by piling brick on brick, or stone on stone. As W. A. Starrett, a leading New York builder, pointed out many years later, “Masonry structures of ten stories and more demanded lower walls of such fortresslike thickness and sparse window vents that the ground-floor space, most valuable of all, was devoured and the sunlight all but excluded.” This difficulty was overcome, however, when Chicago engineers and architects, soon followed by their counterparts in other cities, began designing buildings whose walls did not have to bear any weight, but were simply curtains of glass and brick, uniformly thin from bottom to top, hung on a hidden iron or steel skeleton that held the building up. The first of these buildings was completed in 1885, and five years later New York had a genuine skyscraper, the golden-domed, twenty-two-story building erected by Joseph Pulitzer to house his New York World .
Steam elevators were not well adapted to even quite modest skyscrapers. Not only were they slow, but the drums around which their hoisting cables were wound took up an enormous amount of room when they had to be made wide enough to accommodate the hundreds of feet of cable needed to haul an elevator to the top of a fifteen- or twenty-story building. But as it turned out, the Otises and their competitors were ready with a new kind of elevator, the hydraulic, which took up relatively little space and which could be made to travel at six or seven hundred feet a minute, nearly three times the speed of the fastest Otis steam elevators. This was still less than half the speed at which some modern elevators travel, yet it gave rise to talk of elevator sickness, whose principal symptoms were said to be dizziness and nausea. In 1890 Scientific American suggested, not altogether convincingly, that this new disease was caused by the fact that when an elevator stopped suddenly, some parts of one’s body stopped sooner than others. The best preventive medicine, the magazine advised, was to press one’s head and shoulders firmly against the wall or frame of the elevator car, so that all parts of the body would stop at once.
Many hydraulics were of the direct or plunger type. The elevator car sat on top of a long piston that slid up and down in an equally long cylinder sunk into the ground below the building. When the operator opened a valve letting water from a compression chamber shoot into the bottom of the cylinder, the piston was forced up, and the elevator rose. To bring it down again he opened another valve allowing the water to escape slowly and the piston to sink back into its sheath.
Hydraulic elevators had one disconcerting habit. When left unattended they sometimes took off on their own, slowly rising in their shafts until intercepted and brought back to earth. The usual cause of this creeping, or drifting, as it was known in the elevator business, was a leaky control valve that allowed water from the compression chamber to seep slowly into the driving cylinder. “Of course, if you get careless and don’t check your washers often enough, they creep on you,” the chief engineer of a twenty-six-story New York office building told a reporter some years ago. “Usually, it’s a matter of a floor or two, but over a weekend these babies can work right up to the top story.” Hydraulic elevators could not creep through the roof, however, since they were routinely fitted with safety valves that would let water out of the driving cylinder and halt the upward movement of the car before it reached the top of its shaft.
Water-powered hydraulics, most of which are now equipped with anticreeping devices to discourage nocturnal or weekend wandering, are still in use in some older buildings. They include the Gotham Hotel and Lord & Taylor in New York, Michael Reese Hospital in Chicago, and the Atheneum in Boston.
But for the past seventy years or so, most new buildings of more than five or six stories have been equipped with electrically powered traction elevators. One common variety, first put into use by Otis in 1903, is the gearless traction machine, powered by a variable-speed electric motor located at the top of the elevator shaft. This motor drives a large, deeply grooved sheave, over which pass a set of parallel cables that are fastened at one end to the top of the elevator and at the other to a heavy counterweight. When the sheave is rotated, the friction between grooves and cables causes the elevator to go up or down. In a really tall building an elevator of this sort had a big advantage over a plunger-type hydraulic—it obviated the expensive and tricky job of sinking a cluster of perfectly aligned cylinders hundreds of feet into the rock beneath the building.