Evening star. [volume] (Washington, D.C.) 1854-1972, 1907-09-26

Point, the natural DreakWater is CdlleO,
and who number from 1900 to 1900, ferry
was formerly maintained at the expense of
the city. 1t was inconvenient and, at times,
dangerous, and various plans were suggest
ed to improve the service. a tunnel was
proposed. but was abandoned on account
of Its prohibitory cost; a draw bridge,
lift, a roller bridge were in turn proposed,
but all failed to secure the necessary ap-
prevail of the War Department which would
not consent to any arrangement that would
obstruct traffic.
The Aerial Bridge.
Finally Mr.. Thomas F. McGilvray. city
engineer of Duluth, received a suggestion
which has since been carried out and that
was the adaptation OF the plan of unique
and novel aerial bridge which has been in
operation for century or more at the city
of Rouen, France.
A contract was made with the Steel Struc-
tural Company OF Waukesha, Wis, in 1904
to erect such structure of steel at cost
of slD,OOO and the work was completed un-
der the direction of Mr.. Z. X. Coe civil en-
gineer, in 1905. 1t is a sort OF travelling
crane. "A car capable Of carrying $50 pas
sengers, one loaded double-truck street car
and two loaded wagons with teams, which
are equivalent to a weight of 1854 900 pounds,
is suspended from an overhead bridge or
truss of steel and conveyed by electricity
wheels a distance of 4v5 feet across the
water from side TO side in less than half a
minute. The car platform is thirty-four by
fifty feet in size. In addition to the ample
space for one street car and two wagons
and plenty of deck room it has two cabins
one for men and one for women, each seven
by thirty feet in size.
The truss or overhead bridge is 400 feet
long and Is supported at either end by
skeleton steel towers $50 feet high which
enables any vessel upon the lakes to pass
under X without removing its mastS. The
motive power of the ferry is electricity and
is controlled by an engineer who sits In a
cabin and turns II on or off as 1t is needed.
The car fits into recess in the concrete
wall Of the canal with perfect exactness.
Everything Is set with such mathematical
accuracy that there has been no delay and
no difficulty in crossing from the day the
service began.
The car hangs Just above the water and
1t swings at such an altitude that its deck
Is even with the top of the concrete wall of
the canal Collision with passing ships Is
avoided by signals. And there Is seldom
any Interruption. because the crossing of
100 feet is made in less than minute.
During the last season of navigation more
than 5000 ships passed in and out while
the aerial bridge was in operation and an
average of 1000 passengers were handled
per day by the ferry. The maximum traf-
fc was on April o. 1905. when $1,000 pas
sengers crossed the canal. 7,IS1 in one hour,
and Sl4 in a single trip
The car averages twelve trips an hour
between O'Clock in the morning and
O'Clock at night, and four trips an hour
after 10 o'clock at night. No difficulty is ex-
perienCed from the wind blowing sixty miles
hour. The original cost of the aerial
ferry was 100000 and the cost of main
tenance averages $1,000 year.
People who interested in improving
the facilities for crossing Chicago river
would find 1t to their advantage to investi-
gate this unique bridge. AS have already
Saia. the idea was suggested by little
bridge at Rouen but the bridge at Duluth
is as much larger and finer and different as
the flower is from the seed.
The Ore and Coal Docks
The ore and coal docks of Duluth are not
unique like the aerial bridge. There are
similar structures at other ports on Lake
Superior. and they are also found at Cieve-
land, Ashtabula Conneaut and other Lake
Erie ports. but those here are as large and
complete and perfect as any. The Great
Northern railway. for example has three
enormous ore docks 1900 feet long and 20
feet high. They cost about $500 600 each
and you may judge of their dimensions
when | tell you that the bill for white
washing them this year was $500. White
wash is used as protection against the
weather and fire, and because II gives them
neat appearance. The docks are a net
work of timber. most of 1t eighteen inches
square.
The three Great Northern docks are
capable of handling 100000 tons of ore
during the average season of navigation
each year. This year they expect to han
dle about 100000 tons: an average OF So
each dock Sometimes the receipts and
discharges run up as high as 500 600 daily
and about 100000 tons OF ore Is regularly in
store
The ore is brought from the mines in
cars, which run along the top of the docks
and their contents are automatically
dumped into series of pockets There are
100 OF these pockets, holding go tons
each, on either side of dock-S25 on a
side. Each pocket has a chute made of
steel which projects out over the water SO
that IL can be lowered through the hatch
way Into the hold of a vessel When the
vessel Is brought alongside these chutes
ARE lowered into its hold the traps are
opened and the runs like an avalanche
through the chute by its own weight 1t
/ takes an average of fifteen minutes to
! empty a pocket of $50 TONS but 1t has
! been done in five. The ore is very often
| damp and adheres like clay. SO that men
| with long steel-shod pixies are going up and
down breaking the masses of ore so that
| they may be moved more freely. 1t costs
about 80 cents ton to mine the ore of the
| Mesaba range and place 1t in the hold of a
I vessel The cost OF handling il upon the
! docks, between the car and vessel Is about
| 10 cents a ton. The average earnings Of
} the Great Northern docks are $4,000 day
seven months in the year.
The history OF each car Of ore that comes
out of the Mesaba range is kept in q record
! book by the railway company that handles
y --' 40 settlement of accounts between