The times. [volume] (Washington [D.C.]) 1897-1901, 1901-03-17
By THOMAS C. CLARKE.

I engines can now draw on level 100 steel
cars weighing $500 tons. In the one case
| the paying load of an engine was 40
tons; now, it is 5000 tons.
Steep grades soon developed better
! brake system, and these heavier trains
have led to the invention OF the auto
matte brake worked from the engine, and
also automatic couplers, saving time and
many lives. The capacity of our railways
has been greatly increased by the use
of electric block signals.
The perfecting of both the railway and
its rolling stock has led to remarkable
results
We have no accurate statistics of the
early operation of American railways. In
1867 "Poor's Manual estimated their to-
tai freight tonnage at 75,O00.0 600 tons, and
the total freight receipts at 500, 000f0o.
This was an average rate per ton of IS. 33.
In 1899 Poor gives the total freight tom
mage at 9757S9,94l tons and the freight
receipts at 1920, AZ. 314, or an average rate
per ton of IS cents. Had the rates of
1867 prevailed, the additional yearly cost
to the public would have been i.275, o00, eco.
or sufficient to replace the whole railway
This is an illustration only, but Il very
striking one. Everybody knows that such
high rates of freight as those of 1867
would have checked traffic. This much
can surely be said: The reduction in cost
of operating our railways and the conse-
quent fall in freight rates have been po-
tent factors in enabling the United States
to send abroad last year $l,456 600, 900
with our food and manufactured prod
ucts.
BRIDGE BUILDING.
In early days the building of a bridge
was matter of great ceremony, and ii
was consecrated to protect it from evil
spirits It's construction was controlled
by priests, as the title of the Pope of
Rome. "PontIfex Maximus.' indicates.
Railways changed all this. Instead OF
the picturesque stone bridge. whose long
line of low arches harmonized with the
landscape there came the straight girder
or high truss. ugly indeed, but quickly
built. and costing much less.
Bridge construction has made greater
progress in the United States than
abroad. The heavy trains that We have
described called for stronger bridges. The
large American rolling stock is not used
in England, and but little on the Cont
nent of Europe, the width of tunnels
and other obstacles will not allow of it. |
1t is said that there is an average of one
bridge for every three miles Of railway
in the United States, making $500
bridges, most OF which have been re-
placed by new and stronger ones during
the last twenty years.
This demand has brought into existence |
many bridse-building companies. some of |
whom make the whole bridge, from the |
ore to the finished product.
Before the advent of railways, highway |
bridges In America We're made of wood, |
and called trusses. Few of them existed |
before railways. The large rivers and |
were crossed in horse boats a |
trip more dangerous than an Atlantic
voyage now is. A few smaller rivers had |
wooden truss bridges. Although origi- |
nally invented by Leonardo da Vinci, in |
the sixteenth century, they were re-
invented by American carpenters. Some i
Of Burr's bridges are still standing after
more than one hundred years use This |
shows what wood can do when not over
strained and protected from weather and |
fire.
The coming Of railways required a
stronger type Of bridge TO carry con-
centrated loads, and the Howe truss
with vertical iron rods vas invented
capable of 150-foot spans.
About 1853 iron bridges began to take
The place of wooden bridges Die-forgod
eyebars and pin connections allowed of
longer panels and longer spans- The first
ong-span bridge was a single-track rail-
way bridge of 4O0-foot span over the
Ohio at Cincinnati, which was considered
to be a great achievement in 1870.
The f1nzua Viaduct, $40 feet high and
over half mile long, belongs to this
era 1t is the type Of the numerous high
1iaducts now so common.
About 1855 a new material was given to
engineers, having greater strength and
-enacity than iron, and commercially
AVAILABLE from its low cost. This is basic
steel. After many experiments. the |
proper proportions Of carbon. phosphorus,
sulphur, and manganese were ascer-
aimed, and uniformity resulted The
1pen-hearth process is now generally
ised. This new chemical metal, for such
I is, is 20 per cent stronger than iron.
md can be tied in a knot when cold.
The effect of improved devices and the
Use Of steel is shown by the weights of
he lO0-foot Ohio River iron bridge built
n 1870 and bridge at the same place.
quilt in 1856.
The bridge Of 1870 was of iron. had
panels z feet long. and its height was IS
Get. and span 100 feet.
The bridge Of 1856 was Of steel. had
'anels 20 feet long, and its height was 50
eet. Its span was $50 feet The weights
# the two were nearly alike
The cantiIever design, which is a revival
# a very ancient type. came into use.
The great Forth Bridge. in Scotland.
,60Jfoot span. is Of this style, rs are the
oo-foot spans at Poughkeepsie. and now
new one is being designed to cross the
It. Lawrence near Quebec, of ,s00-foot
pan.
This is probably near the economic limit
+ cantilevcr construction, but the sus-
ension bridge can be extended much |
arther. as it carries no dead weight OF
impression members.
The Niagara Suspension Bridge Of $40 |
GOT span, built 10y Roebling, in 1852, and
he Brooklyn Bridge. of 600 feet. built
" Roeblng and his son, twenty years | {
fter. marked q wonderful advance in
ridge design.
Thirty years later, when a new bridge
Loo feet was wanted TO cross another
art of the East River at New York. the
anne lines of obstruction were followed, ]
nd they will be followed in the 2,7OO-foot !
pan, designed 10 cross the North River,
IL,