The daily union. [volume] (Washington [D.C.]) 1845-1857, 1846-06-01

FLOATING DRY DOCKS.

The debate ON the comparative claims Of the bal
snce and sectional docks has at last spproximated
apparently to the principles Of the "science Of fols
tation, !" in small pamphlet just published under
tile tide Of NM Gilbots reply 70 Mr.. .aisas ns.s
doctrine on The principle g stability In floating sirue
lures" Heretofore, the discussion has boon more
or less loose and obscure. "Flotation" is ranked
among the sciences as much geometry, and is de-
nionstrated by lines and angles AFTER the manner Of
Euclid's Elements. A person can no more under
stand "hotation" than Euclid, without passing
through the stages Of proof. The results admit Of
not particle more Of uncertainty or doubt in one
case than in the other. The principles Of "the
science Of fotation" strictly applicable TO the
question Of the r.laiUt and eOmpaaius stability Of
the balance and sectional docks. Mr.. Gilber's re-
ply shows Mr.. Allen to be, either ignorant Of the
science, or Intentionally perverse in misrepresenting
Its principles! The writer has witnessed the de-
monstrations by models prepared by the COMMITTEES
of a town meeting Of Philadelphia, which are now
being exhibited at the Capitol in this city, by the
chairman Of that committee. These demonstrations
prove that Mr.. Gilbert is right and Mr.. Allen
wrong-that the balance dock is a firm and stable
structure for is purposes, and that the sectional
dock Is comparatively unstable, fral and dangerous
The argument is purely scientific one, and every
experiment proves that the principles Of the science
arc correctly ascertained and immovably estab-
Iished.
The following letter from Commodore Stewart,
published at the end Of Mr.. 0ibers reply 10
Mr.. Allen, and coming, as il does, from a well
known naval officer, whose opinion on this subject
cannot but be the result Of long experience and thor
ough observation, is eminently worthy of consider.
alton:
Copy Of a letter FROM COuiutOdors slspsrt.
PHLADELrHIA, May q, 1876.
DEAR SIR: have received your letter Of the 23d
instant, with the enclosed BILL now before the House
OF Representatives, for the construction Of floating
balance dock at Philadelphia, and floating section
al dock at Pensacola; 70 all Of which have given
my most deliberate consideration.
There 3 no Pogtion az the Phladephis naval
station where sufficient depth Of water can be ro-
tanned al all times and in all tldes for the docking Of
ship of The line even ioilhoui her armament, Ia
sectional dock in CONSEQUENCE Of the greater draugh
Of water required by that kind Of dock, for the lift
ing or submerged tanks under H. As the bill pro-
vides very properly for the construction Of "baL
ance dock" at this station, Of these disadvan
tages viii accrue in consequence; and the balance
dock will not require permanent insular wet dock
for lis retention, II can be at all times removed to
any point place most venent for its purposes
and Will also possess the camel properties Of lifting
and bringing 10 any place In the river vessel draw
ing more water than the river admits OF. This is
highly important consideration, ard decided adj
vantage which the balance dock possesses over the
sectional one II is this account that regret the
balance dock not also contemplated for Pensaco-
la; and apprehend il will be found in practice at
that place, that the sectional dock will be rem
dered useless by the filling up Of the permanent wet
dock in which il is retained, the downward cur
rents constantly carrying moving sands and FL
ling up all recess places open to those waters. This
could not occur with the balance dock, which is
always capable Of being removed from any place
which may, from any cause, become unsafe, to one
more secure. Now, l deem this fact an important
consideration for the navy yard at Pensacola, be-
cause, as that place may be bombardcd from the sea
in its rear floating dock Of the sectional kind, with
ship Ia Il, would be liable to be set on fire, under
such circumstances, because il could be remov.
ed while the balance dock could be taken out of the
way, UP the EscaIba river, If necessary. Further:
without the camel properties Of the dock at Pensa-
COLA TO lin ships Of the line tie bd, there could be
no ships of the line to dock at that place.
I hope the committee or House will amend the
bill 30 that balance dock may be constructed at
both places.
Very truly your friend and obedient servant,
CHS. STEWART.
WoopsuRNE POTTER, ESQ,
. .. Washington, ID. c.