a city; and after great toil, and at the cost of the lives of unnumbered
labourers, the work was done--so well done, in fact, that much of it is
still standing, and some is still doing service.

In much the same regal way the managers of a railroad order a steel
bridge flung across a chasm in the midst of a wilderness far from
civilisation, or command that a new structure shall be substituted for
an old one without disturbing traffic; and, lo and behold, it is done in
a surprisingly short time. But the new bridges, in contrast to the old
ones, are as spider webs compared to the overarching branches of a great
tree. The old type, built of solid masonry, is massive, ponderous, while
the new, slender, graceful, is built of steel.

One day a bridge-building company in Pennsylvania received the
specifications giving the dimensions and particulars of a bridge that an
English railway company wished to build in far-off Burma, above a great
gorge more than eight hundred feet deep and about a half-mile wide. From
the meagre description of the conditions and requirements, and from the
measurements furnished by the railroad, the engineers of the American
bridge company created a viaduct. Just as an author creates a story or a
painter a picture, so these engineers built a bridge on paper, except
that the work of the engineers' imagination had to be figured out
mathematically, proved, and reproved. Not only was the soaring structure
created out of bare facts and dry statistics, but the thickness of every
bolt and the strain to be borne by every rod were predetermined
accurately.

And when the plans of the great viaduct were completed the engineers
knew the cost of every part, and felt so sure that the actual bridge in
far-off Burma could be built for the estimated amount, that they put in