Rock Island daily Argus. (Rock Island, Ill.) 1886-1893, 1892-11-07

bility. IL is now Il question IF mat leIila--
les rather than Of personal experience. Il
is now a matter Of apple: se-raee and rot
one of fortunate gue~ % The con
structor in these days do, y TX t.,. scale
of the inclined plano co-A mich ti.c YES
| sci will glide by his experience IL such
matters; does not smear the tSl.ov- on ti.=
| ways until il seems 70 }e croHgn: does Tot
| adjust the size of the ways 20 suit his
! fancy. Vessels that cost from $1.CS1.0s50 20
s., oO0, 600 are too valuable for the running,
of large risks, ard hence the equal ion. the
| formula, the methods Of applied rnathe-
! matics, have sUpplanted old time ways Of
! trusting to individual Judgment and good
! luck.
| Three things are absolutely necessary in
| launching a vessel in tidal waters-the
| launch must take place on time. must be
| Of moderate speed, and all straining of tie
| vessel must be avoided. 1t Is in this last
particular that the greatest responsibility
| rests nowadays. a wooden vessel may be
| subjected to a great strain, her seams may
open and, as a naval constructor recently
| put it, she may almost be stood on her
head" and yet escape serious damage in
| launching The seams will close again
| and the tim bers and plsnks adjust them
! selves. Not so with iron or steel vessels
| Ii the plates are strained, the rivets bent
| or broken, the injury is permanent and a
matter OF the Cravest Importance.
Preparations -OE X lduf-tL are begun De
fore the keel is laid. The incline Of the
plane has first TO be figured out. 1t gen
orally varies from one-half inch 10 one inch
TO the foot. Vessels Of a large tonnage
! have less inclination than smaller ones.
The City of Paris had only one-haif an inch
inclination when she was launched. The
cruiser Columbia 50 long known as the
Pirate, and recently launched at Cramps
shipyard in Philadelphia, glided into the
water at an inclination OF thirteen-six-
teenths of an inch to the foot. She went
down he ways like a race horse. Mr.. Nixon.
the constructing engineer of the Cramps.
planned 10 have her in the water in thirty
seconds after she started. She uad. il IN
enty-DIue. More vessels are launched
AZ an inclination Of three-quartos - OF al
inch TO tie foot, however. than At any other g.,
plane.
The ways d j. generally known. con
SYST Of two parts the ways TcCsag and til
cradle lie ways q ger are stationary
.-' i.rU-iE saSS-s.t. 20 tlc ground. Tie
,-aoIe rests on tas oi Jae ways aEo. up
gains, tie vessel and slides .utot.e water
with the snip Be; 9Veen TLe way proper
and TIE cradle the tsilCT Is s0selrec. This
i generally spread Evc-ei-a,a~ q an inch
thick and must la OF the highest grade
That used by tie Cramps ! made in Phil
adelphis ana costs from seven 10 eight
cents pound. About L 900 pounds was
a.
heated ia biz, kettles III the shipyard and
spread on by hand In the case of the
Pirate the wcst her was 50 warm that there
was serious danger that the tailow would
melt and r1ln away. Mr.. = jXou therefore
mixed - per cent. sJcarire with it. lie
also played hose on the talloye, and went
so far Is to sit up nights with the mixture
to watch the effect of the weather on it.
The stearine hardened the tallow and the
launch was successful
Perhaps the most important element TO
be considered in the launch of today is the
buoyancy of the water and its effect on
that part of the vessel which is still on the
stocks after probably half of the vessel
is in the water. Recently one of the new
English battleships of the Il, 000-ton class
was wrecked at her launch The buoyancy
of the water lifted her up at the heels and |
threw her immense weight forward on her
shoulders, crushing the frames and the |
launching ways, and running the boat. |
The modern naval constructor reduces this |
question of buoyancy to a matter of mathe- |
matlcs at once. He starts with the cues |
ton of specific gravity of the vessel. IL |
there were no water for the ship to slide |
into she would continue in the line of the |
ways until the center of gravity would get |
over the end of the ways, and then she |
would tilt. But the water keeps her from |
dropping down and holds the vessel in the |
line of the ways. This water is the safety |
valve of the launch, but it must not be too |
safe. While the moment of buoyancy |
must always be greater than the moment |
of weight, 1t must not be so much greater |
as to throw terrible pressure on the for
ward end of the vessel and wreck ii.
Having arranged all these things, day
and hour are set for the launch, the
time of the high tide being the chief factor
to be considered. Most of the props are |
taken down and the vessel rests Ga the keel
blocks nd or ryr1 Of 81 Is nj ha
sides. The ways and cradle have been fixed
in place, and wedges have been adjusted /
above the cradle and under the poppet
blocks on which she rests. 4 battering
ram consists of four men to n piece of stout
timber. These four men take care of four
wedges. The signal is given and an i'm
mense clatter begins the men drive
home the wedges for five minutes The
vessel is lifted just clear of the keel blocks
and now rests on the ways. Alternate keel
blocks now knocked away, beginning
ut the stern Another ''wedging up'' fol-
lows, and then all the props at the sides
are removed.
After rest the third wedging comes,
and then all the keel blocks are knocked
down, the word Is given. and the planks
that hold the cradle to the ways proper at
the bow are sawed off, and the vessel starts
down to the water. This is the supreme
moment in the shipbuilder's career. In
thirty seconds all the responsibility of his
past and his future is crowded upon him. |
Those who know the intense strain that
rested on Mr.. Nixon at the launch Of the |
New York. the gayest occasion in ship |
building this country has ever known, and
of the Columbia, realized what the big |
sigh meant that he drew when the vessels
got off safely. Had he been a woman in |
charge of SO grave an occasion he probably |
would have swooned after it passed off sue |
1t took about 600 men to launch |
these boats and their services and the tai