The New York herald. [volume] (New York [N.Y.]) 1840-1920, 1879-01-29

Whlie We may Justly congratulate our
selves on the progress made in naval archi-
lecture, by which the comfort of the pas
senger and the carrying capacity of the
ship are increased. it is question whether
we have also secured in proportionate
degree the all-important condition of safety.
without which luxurious accommodations
and superior capacity for cargo are but
nominal advantages. Since the virtual
Abandonment of wood as the chief material
In the construction of steamships the skill
of the naval architect has been directed
toward giving the substitute, iron. power
Of hotation which would wholly justify the
change. Iron, as we all know, is q sub
stance whose specific gravity is vastly
greater than that of most kinds OF
wood used in shipbuilding. 1t pos
sesses, however, an enormous tensile
strength consequently the dimensions
Of ships parts can be reduced
in iron SO as to make the relative weights
of the material employed about one-third
less in favor Of iron-that is to say, a wooden
ship Of one thousand tons cargo capacity
weighs in the dock about one-third more
than one of the Same capacity built of iron.
AS the Aotation of ship is governed by her
displacement, which is always equal to her
dead weight and that of her cargo, the iron
vessel possesses the primary advantage of a
smaller displacement, and consequently a
greater carrying capacity, than ship of the
same exterior dimensions built of wood.
1t is, however, more important to the
safety Of an iron ship that her construction
should be perfect than to that of
wooden vessel. How is that perfection
of construction secured for an iron ship?
First. by rendering her walls OF sides and
bottom absolutely impermeable to the
water, which always seeks to fill her with
pressure that increases from the load or
water line to the keel Second, by pro-
viding sufficient pumping power on board
to overcome any leakage due to defective
construction or caused by damage to the
immersed part of the hull. Third, by what
are termed watertight partitions, which
divide the ship into o number of Sec
tons, and SO localize the influence
of the leak or it's cause, the rup-
ture of the sides or bottom. Let us explain
in few words how these operate. Take q
bowl made of light wood and set it afloat.
1t will sink just to the depth whereat the
weight of the wood will be equal to that of
the water displaced by the bowl. Now,
take an iron bowl of the same dimensions,
and it will sink until the weight Of the
water displaced is equal to the weight of
the iron in the bowl. Suppose We fill the
wooden bowl to the brim with water; it
will sink until there is just so much
water displaced by the bulk of the
wood rs is equal to it's weight plus
the weight of the added water until the
contained and exterior surfaces of water
coincide, when the displacement becomes
only that Of the volume of the material in
the bowl. Then it will float with its
brim on the surface like a water
logged ship. If this last experiment is
tried with the iron bowl the moment the
interior and exterior water surfaces coincide
the bowl sinks to the bottom, because its
volume displaces a less weight Of water
than that of the bowl itself Now, suppose
we divide the iron bowl into sections by
two interesting partitions, and that we fill
to the top two of these; the bowl will sink
deeper in the water, but will not be SUBJ
merged, because of the support afforded by
the empty sections, which naturally keep
the displacement within the limit of buoy
ancy.
Referring to the important questions in
volved, we print elsewhere to-day brief
communication from Passenger" who
complains that the watertight bulkheads or
transverse partitions, which steamship
owners claim to be guarantees against
danger at sea, are too frequently the causes
of disaster, because while relying on them
the officers of such vessels fail to adopt
measures for making them reliable 1t is
well known that there are openings or
sluice ways between these sections or COM
partments, and that these, either through
neglect or indifference to danger, IRE not
closed by sluices or gates during
the time the ship is exposed to danger from
collisions or other casualties of the seas. II
these sluices are open there is no longer q
watertight bulkhead in the ship, and if her
bow or side is stove in she will fill from
stem to stern and 60 down. Nothing can
be moro absurd than to build these heavy
bulkheads in vessel unless they are made
to serve their proper purpose. Without
their closed gates, shutting off all posi-
BILE communication between the compart-
ments, thcy are as useless as projections
against disaster rs tho uncovered ribs
and stick of n skeleton umbrella
would be as q shelter against the rays of
MONDAY sun. Unfortunately, familiarity
with an ever present danger is calculated
to breed contempt for it. and the fata!
moment arrives when that which is looked
upon as only remotely possible occurs.
Then the contempt for danger becomes On
equally senscless fear of il, INDIGESTION sue