774 
enty dollars, was two hundred and fifty dol- 
lars per ton. Now steel is produced at less 
than thirty dollars; single steel firms pro- 
duce millions of tons each year, and the 
annual product of the world is nearly thirty 
million tons. To show the great growth of 
this interest, Sir Henry Bessemer illustrated 
the total production of Bessemer steel of 
the world by saying that if the product of a 
single month were made into a solid shaft 
of one hundred feet diameter it would reach 
557 feet high. This illustration of the 
world’s production eight years ago is now 
equally applicable to the United States 
alone, nor does it include the production of 
open-hearth steel, or wrought or pig iron, 
the total for the world approaching eighty 
million tons annually. There is hardly 
any personal, municipal or corporate life, 
or hardly an enterprise of war or peace, 
that has not more or less closely connected 
with its development the use of this re- 
markable engineering material. 
In the domain of the civil engineer prog- 
ress is none the less marked. Within a 
score of years there has been developed the 
tall office and other buildings of the steel 
skeleton type, where the engineer has had 
to so design the steel frame that it will 
support sixteen, eighteen or twenty stories, 
crowded with busy life and industry, as 
well as to bear the weight of the walls and 
the great wind pressures that such high 
buildings sometimes must sustain; and not 
only this, but he has so considered and con- 
trolled methods and materials in the design 
and in protecting this all-important steel 
skeleton from fire that the occupants are 
safer in them than in the older style of 
building. Steel bridges have had a longer 
reign, though less than forty years ago it 
was considered a very remarkable feat to 
build an iron bridge whose length of span 
was 320 feet. Thirty years ago the magni- 
ficent steel-arch bridge of our own city, 
consisting of three spans, with the central 
SCIENCE. 
[N. 8S. Vou. XIII. No. 333. 
one 520 feet in length, was erected by Cap- 
tain Eads. Twenty years ago the Brooklyn 
suspension bridge, of 1,600 feet length of 
span, was being constructed. Ten years 
ago the great cantilever bridge across the 
Firth of Fourth was built, containing two 
spans of 1,710 feet each. And now there are 
plans, perfectly practicable, for a suspension 
span of 3,200 feet, to carry eight railway 
tracks across New York harbor and to weigh 
between sixty and seventy thousand tons. 
In railway affairs the engineer has perfected 
the problems of transportation as we have 
seen, until the total mileage of the century 
is great enough to girdle the world fourteen 
times. In questions of water supply and 
sewage all our cities provide systems as a 
necessity, where a hundred years ago they 
were the luxuries of the very few, and woe- 
fully inadequate at that ; and the engineer 
and the biologist have been colaborers in 
developing successful methods of prevent- 
ing danger of contagion from these public 
utilities. Harbors’and docks have been 
constructed and improved consonant to the 
spirit of the age. Foundations for great 
bridges and towering buildings are carried 
to depths requiring methods and inventions 
of particular resourcefulness, including the 
famous pneumatic processes. The develop- 
ment of hydraulic principles has made pos- 
sible a varied series of achievements of far- 
reaching significance. Irrigation enter- 
prise, which had been dead for centuries in 
its ancient home and was dormant even in 
India, has spread over the arid regions of 
the globe and is making oases of the waste 
places of the earth. In only two-thirds of 
the year one of the small canals of the cen- 
tury transports merchandise of a greater 
value than have the imports of China, for 
which the great world powers are so stren- 
uously alert. The construction of the pro- 
posed canal from ocean to ocean across 
Central America will be a stupendous 
undertaking ; humanity has never ceased to 
