Evening star. [volume] (Washington, D.C.) 1854-1972, 1901-02-23

ton will not be greatly changed henceforth.
The dimensions of the bridges Will be In
creased. even multiplied; materials will be
improved and strained much higher than
is now allowed. Steel truss bridge spans
may reach. but will hardly exceed, 5000
feet. Suspension bridges can be built long
er. Fifty years ago iron had strength of
barely $1,000 pounds per square inch. The
latest steel specifications call for 200,o0o
pounds and this will be exceeded by metals
of still greater strength. While limits may
be set to the length of single spans, they
cannot for bridges as a whole. The long
proposed bridge across the English chan
mel only needs political and financial au-
thorization to be possible. The second larg-
est and much the grandest bridge in the
world is well under way to connect the
boroughs of Manhattan and Brooklyn. 1t
will have a river span of LOO feet,
width of 11S feet, twice as great as an
ordinary street; will carry six lines of rail-
road track and have a total weight of more
than a hundred million pounds.
Steel buildings are the notifications of
bridge work., and their sudden appearance,
giants at BIRTH is the most remarkable ex-
ample of a whole class of great structures
coming to perfection without a slow de-
velopment The heights of the thirty-one
story Park Row building in New York city,
which is 424 feet, will hardly again be
eQualed, unless for mere notoriety, because
1t is unnecessary and undesirable, but the
greatest existing roof span will doubtless be
much exceeded, and can even be multiplied
almost ten fold If any reason should JUS
tify such vast expense. Structural freaks,
like the ZOO feet high Eiffel tower and the
Ferris wheel, $50 feet in diameter, will be
limited only by the range of ingenuity and
the strength of materials.
The construction of massive foundations
under water for bridge piers and in treach-
erous soils for tall buildings has developed
special designs of steel and concrete, and
ingenious scientific methods of pile driving.
pneumatic caisson work, ETC., which nave
reached a high degree of perfection, but
of 1hSfr1 1rt1l will ".
and new methods and appliances will surely,
be invented.
The Municipal Engineer.
| In two or three years Manhattan Islands
present daily supply of 200,000,OO0 gallons
| of water will be increased by the storage Of
80 600, DOC, 000 gallons of water in a reservoir
| fifteen miles long and 157 feet deep. This
will be formed by the building of the world s
| greatest dam, which will cost S6,0OO,00O Its
| vast mass of masonry will rise about 800
| feet above it's foundations which have been
sunk 40 feet below the bottom of the river
which they cross.
In municipal engineering feats such as
| this there will be vast advances in the years
| to come. Unpoluted drinking water will be
supplied to the public, and if it is not avail
| able without 1t will be filtered on a great
| scale. Vile sewage will be filtered, chem
| ically precipitated, or made a valuable irri-
CANT. Garbage and solid refuse will not be
| left to putrefy in the streets or burned at
| dill eApeHSe, out Will De TeUuceQ IN large
| plants, whose product will yield a profit
| Heat and cold, light and power will be dis
| seminated from central stations as water
and gas now are. Real rapid transit will be
| secured by complete tunnel and viaduct sys-
| TENS in great cities, and the trains will be
| drawn by SILENT smokeless speedy motors
Already the displacement of draught ami
| mails in cities by automobiles has COM
menced. Improved methods and economies
| in generating, Transforming and storing
| power will more and more supplant human
| labor as well as multiply automatic We
| hicleS for business and pleasure on land
and water. There is as yet, however no
| sign of discoveries revolutionary enough to
realize that allurng mirage, aerial naviga-
| ton. No single invention will accomplish
It, and the slow development which leads to
| great engineering possibilities does not yet
| predicate for this.
| The Work of Publication.
| The field of the sanitary engineer has
| been almost entirely comprehended in that
| of the municipal engineer. His part will
| to be aerate, OXidize filter water sup
| plies; to protect them, sometimes in vast
covered reservoirs He will drain swamps
and reclaim poisonous marshes. He will
| so proportion great sewers that the COM
paratively clean floods from storms will
| be safely carried away by them and harm
| lessly discharge into rivers, while the
smaller flow of sewage is taken to the dis
pOSal grounds. Where the city is too low
ana nat LOT sewer grades ne VIII eSlaDllSn
wells and pump their contents to its final
destination. His will be the task to wash
out foul rivers, as in Milwaukee, where the
| contents of a large tunnel are continually
| forced by a great pump, from the lake, to
flush out an otherwise stagnant river. In
his hands will lie in large measure the
health and comfort of millions of people
| in all cities.
In general, the results of engineering will
continue to increase in geometrical pro-
| gression. Improved methods will permit
larger and larger scale constructions, most
of them will change in quality, rather than
in kind, and new discoveries and inven-
lions will bring about developments rather
than sudden transformations. Within the
limits of scientific and mathematical laws
and the strengths of materials almost any
great constructions that can be accurately
designed may now be built If unlimited
time, money and opportunity be granted
| The criterion of what will be done will
| generally be, "Is 1t humanely or politically
necessary or is 1t financially justfied?"
.