Castles in the sky: how new York city's colossal skyscrapers were constructed

High above the streets of Manhattan, the teams of riveters worked to a set routine. As an enormous crane hoisted each steel beam into place on the growing Empire State Building, a workman called the "heater" warmed each rivet in a portable furnace until it glowed cherry-red, removed it with tongs and tossed it to a "catcher", perched precariously on the very edge of nothing. Usually he caught it in his "catching can", but sometimes he missed. Using tongs, the catcher knocked off the cinders and lodged the rivet in the prepared hole. Another workmate held it firmly with the aid of a heavy steel bar, while a third smashed the rivet into place with a compressed air hammer.

It took 60 000 tons of steel to build the Empire State. The beams and girders were cast in Pittsburgh, and within a day or two of being made, each numbered piece had been transported to Manhattan, hoisted into position and riveted into place. There was little storage space available on site, so elaborate charts and timetables were used to monitor progress and to ensure that deliveries kept precise pace with the erectors' and riveters' schedules.

316 I Английский языкдля студентов строительных специальностей

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Careful organisation builds a giant.

The charts listed every lorry due to arrive, what it would carry, who would be responsible for it and where it ought to go. Each beam was hoisted by crane to the appropriate floor, then transported to wherever it was required on a miniature railway system. This methodical approach worked exceptionally well and on occasions the building rose by more than a storey in a single day.

The Empire State 102 storeys were finished in record time. It took just six months to complete the 381 m building instead of the anticipated 18 months, feat that set new standards of efficiency for the construction industry. But it was 1931, in the early years of the Great Depression, and much of the space remained unlet. The building was dubbed "The Empire State Building". It had cost $24 million to construct, which was cheap at the time, but for the first few years a major source of income used by the developer to pay property taxes was ticket sales for the observatories on the 86th and 102nd floors. From the top on a clear day, it is possible to see 80 km away. A skyscraper made of steel.

The steel skeleton of the riveted structure means that it is immensely strong — the building sways less than 6 mm on the 85th floor in a strong wind. In July 1945 an off-course US Air Force bomber, travelling at a speed of 400 km/h in fog and rain, crashed into the 78th and 79th floors. The three man crew and 11 people in the building were killed, but the structure suffered no permanent damage. Survivors recall that the building simply rocked a couple of times.

Manhattan's distinctive skyline started to take shape when steel began to be used for tall buildings. Earlier buildings had been made from a variety of materials, including stone, brick, wood and cast iron. But a masonry building taller than about ten storeys would have required supporting walls so thick at the base that there would be hardly any floor space on the ground floor and, before lifts were invented, building height was limited to the number of steps people were prepared to climb. One of Manhattan's most striking early skyscrapers, built between 1901 and 1903 was Flatiron building. It owes its unique shape to the narrow triangular site it occupies at the junction of Broadway and 5th Avenue at 23rd Street.

Twenty storeys high, its riveted steel frame is clad in French Renaissance-style stonework.

Taller and taller.

The Flatiron may also have been the first building to create strange aerodynamic effects in the surrounding streets. Even today, Manhattan's tall buildings create unusual wind currents, causing snowflakes to float upwards. Before long, the Flatiron was dwarfed by other skyscrapers, including the Woolworlh Building, completed in 1913. The architect, Cass Gilbert, chose the Gothic style for the 60-storey tower. The structure itself was made from steel and the exterior completely clad in terracotta. It could house 14000 workers, serviced by 19 lifts and 2800 telephones — an astonishing number for the time.

When the building was finished it won immediate praise from the public — but some architectural purists were aghast, their sensibilities offended by Gilbert's use of Gothic detail purely for decorative effect, rather than for structural purposes. This was contrary to the modernist stricture that "form should follow function".

(Reader's Digest: How Was It Done? The Story of Human Ingenuity Through the Ages, 2000)

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