The St. Louis Republic. [volume] (St. Louis, Mo.) 1888-1919, 1901-03-17

, built q bridge over Charles River at Boston
/, lao feet long by forty-si1 feet wide. Thi
! bridge was of wood supported on piles. HI
work gained for him such renown tina
he was called to Ireland and built q sim
liar bridge at Belfast.
Tunnelins by compressed air ID . horizon
tai application OF compressed-air founda'
lions. The earth IL supported by an iroI
tube. which is added to in rings, which arr
pushed forward by hydraulic Jacks.
A tunnel Is now being made under an arm
OF tho sea between Boston and East Bos'
ton. some Loo feet long and sixty-fve fee
below tide. TIT interior lining Of iron tubing
Is not used. Tho tunnel II built of concrete
REINFORCED BY steel rods. This will sffeot
considerable economy. Success in modern
engineering means doing a thing In the
most economical way consistent with safety
The St. Clair Tunnel, which carries the
Grand Trunk Railway Of Canada under the
outlet Of Lake Huron, 10 a successful ex-
ample Of such work. Had the North Rivel
Tunnel, at New York. been designed on
equally scientific principles. 1t would prob
ably have been finished. which now seems
problematical.
The construction of rapid-transit railways
In cities Is another branch Of engineering.
covering structural. mechanical and cleo
trical engineering. Some Of these railways
are elevated. and are merely railway via
ducts. but the favorite type now Is that Of
subways. There are two kinds. those near
the surface. like the district railways of
London. the subways in Paris, Berlin and
Boston. and that now building in New York.
The South London and Central London. and
other London projects. are tubes sunk fifty
to eighty feet below the surface and requir-
ing elevators for access. These are made
on u plan devised by Greathead. and consist
Of cast-iron tubes pushed forward by by
draulic rams. and having the space outside
OF the tube filled with liquid cement pumped
into place.
The construction Of the Boston subway
was difficult on account OF the small width
Of the streets. their great traffic and the ne
cessity of underpinning the foundations of
buildings. All of this was successfully done
without disturbing the traffic for a single
day. and reflects great credit on the engi-
neer. Owing to the great width of New
York streets. the problem is simpler in that
! respect, but requires skill in design and or
ganization. to complete the work in a short
time. Although many ines as long as the
Boston subway. it will be built in nearly
the same time. The design. where in earth.
may be compared to that of a steel office
building twenty miles long. laid fiat on one
of its sides. The reduplication of parts
saves time and labor. and Is the key to
the anticipated rapid progress. Near the
surface this subway is built in open excava-
ton, and tunneling is confined to rock.
The construction of power-houses Tor de-
veloping energy from coal and from falling
water requires much structural besides cleo
trical and mechanical engineering ability.
The Niagara pOwer-houSe is intended to de-
velop 100. 600 horsepower; that at the Saulte
| ste. Marie as much; that on the st. Law
renee. at Massena, 1900 horsepower. These
are huge works. requiring tunnels. rock-cut
chambers and masonry and concrete in
walls and dams. They cover large extents
Of territory.
The contrast in size of the confusing
power-houses Is interesting. The new pow
er-house now building by the Manhattan
Elevated hallway. in New York. develops
in the small space of 200 by 400 feet 10o.N0
horsepower. or as much power as that
utilized at Niagara Falls.
One of the most useful materials which
mouern engineers now make use OF Is con-
crete, which can be put into confined
spaces and laid under water. 1t costs less
than masonry, while as strong. This Is the
revival of the use of a material used by
the Romans. The writer was once allowed
to climb a ladder and look at the construc-
tlon OF q dome Of the Pantheon. at Rome.
He found it a monolithic mass of concrete. J
and hence without thrust. 1t Is a better
piece of engineering construction than the I
dome of st. Peters. built 1.5O years later.
The dome Of Columbia College Library, in
New York, is built of concrete.
Concrete is a mixture of broken stone or
gravel, sand. and Portland cementA Its vir-
tue depends upon the uniform good quality !
of the cement. The use of the rotary kiln,
which exposes all the contained material to
a Uniform and constant inteIse heat. has
revolutioniZed the manufacture Of Port
land cement. The engineer can now depend
upon its unifority of strength.
Wheels. axles. bridges and r Ills have all
been strengthened to carry their increased |
-. 49, A. --,, ~ rlt-~ Ill 4
hold in place the ends Of the rails, and
which are really short-span bridges. are
now the weakest part of a railway. The
angle-bar splice has but onesthird of the
strength of the rail. and its strength can
not be increased. owing to its want Of
depth. Joints so down under every passing
wheel. and the ends of the rails wear out
long before the rest.
This is not an insignificant detail. It has |
been estimated by the officers of one of the
trunk lines that a splice of proper design
and strength would save yearly enough in |
track labor (most of which is expended in
tamping up low joints to buy all the new |
rails and fastenings required in same time.
1t &ould save much moro than that in the
wear of rolling-stOck. A perfect joint would
be an economic device next in value to the
Eessemer steel rail. Here Is a place for
scientific and practical skill.
HYDRAULIC ENGINEERING.
This is one of the Oldest branches Of en-
cheering, and was developed before the
last century. The irrigation works of Asia. |
Africa, Spain, Italy. the Roman aQue- |
ducts. and the canals of Europe. are ex-
amp.es. Hydraulic works cannot be con- |
structed In ignorance OF the avs which !
govern the flow of water. The action Of
water Is relentless, as ruined canals, OBJ |
structed rivers and washed-out dams do
testify.
The principal additions Of the Nineteenth
Century to hydraulic engineering are the
collection of larger statistics of the flow
OF water in pipes and channels. of rainfall, |
run-of, and available supply. 1t is now
known that the germs of disease can he
retained by ordinary sand filters. and it is
now an established fact that pure drinking
water and proper drainage are a sure pre-
ventive of typhoid and similar fevers. Very
foul water can be made potable. Experi-
ments show that the water of the Schuyl-
400, 600 germs in the space of less than a
cubic inch. was SO much purified by filter
ing that only sixty remained. This is O
discovery of sanitary science, but the ap-
piication of it is through structural en-
cheering. which designs and executes the
filter beds with great economy.
The removal of sewage, after having been
done by the Etruscans before the foun-
dation of Rome. became a lost art during
the dirty Dark Ages, when fifth and piety
were deemed to be connected In some mys-
terious way.
John Wesley on Cleanliness and
Its Relation tn SEWERAGE Systems.