How is it possible to erect such building--how is it possible to erect
a sky-scraper at all? A partial answer may be given in one
word--_steel_.

Generally speaking the method of building all these huge structures
is much the same. Massive piers or pillars are erected, inside which
are usually strong steel columns; crosswise from column to column great
girders are placed forming a base for the floor, and then upon the
first pillars are raised other steel columns slightly decreased in
size, upon which girders are again fixed for the next floor; and so
on this process is continued floor after floor. There seems no reason
why buildings should not be reared like this for even a hundred stories,
provided the foundations are laid deep enough and broad enough.

The walls are not really the support of the buildings. The essential
elements are the columns and girders of steel forming the skeleton
framework of the whole. The masonry may assist, but the piers and
girders carry the principal weight. If, therefore, everything depends
upon these piers, which are often of steel and masonry combined, the
immense importance will be seen of basing them upon adequate
foundations. And thus it comes about that to build high we must dig
deep, which fact may be construed as an aphorism to fit more subjects
than the building of sky-scrapers.

To attempt to build a sky-scraper without a suitable foundation would
be tantamount to endeavoring to build a house on a marsh without
draining the marsh,--it would count failure at the very beginning. The
formation depends on the height, the calculated weight the frame work
will carry, the amount of air pressure, the vibrations from the running