Richmond dispatch. [volume] (Richmond, Va.) 1884-1903, 1885-08-23
THE SCREW DOCK.
C. P. E. BURGWYNS REPORT.

pTQNemtHt AOlulnltttc ut}N tos~4N Ne+f
present, Chairman Crenshsw and
Messrs. Gum. Dickerson, Rose, Allen,
Dunlop, and Hawes-the following re-
port Of Colonel c. =. Z. Burgywn was
presented, read, and adopted as the re-
port Of the committee
RICHMOND, VA. August "a, 1850.
J. c. Dickerson, Esq, Chairman Sub
Committee Improvement cf James
Rirer
Dear Sir,-I have the honor 70 sub
nit the following report Of the opera
tons on the construction Of the screw
dock. which | have just turned over TO
your committee.
After the passage Of the apprOpris-
tion / was authorized TO prepare plans
and specifications preparatory to otier-
ing the iron-work TO contract. These
were duly prepared, examined, and ap-
proved by the committee, proposals
were invited. bids were received from
all the leading iron-men in the city, and
the contract was awarded to the Tan
ner q Delaney Engine Company they
beng the lowest bidders. When the
question Of location Of the dock arose 8
subcommittee was appointed 10 look
into this matter, and il was finally set
tied by the COMMITTEES leasing for
a period Of ten years from the Parker
estate tract Of land fronting
3l3 feet on the river north Of the old
Abraham S railway, and running back
400 feet between parallel lines. Work
was actively commenced on the dock on
the 18th Of June. and was completed
and q vessel hauled out on il on the llth
Of August. During this period, how
ever. the force at my disposal was also
utilized IL executing the works Of pro
lection" mentioned in previous re-
port as necessary for the site Of re
ceiving station. ] visited the several
docks at the North, taking notes and
sketches Of the various appliances there.
and the present dock is the result Of
these studies.
The weight Of the uplifted vessel is
borne by iron girders. which were sub
stituted for the wooden cirders Of the
original plan. the change being autho-
ri2ed by the committee at my request.
These iron cirders are SIX II number.
twelve feet from centre 10 centre. three
feet deep. OF plate glrder construction.
with q twelye-lnch tange on top and
bottom. They are supported bv iron
straps OF rectangular cross section. one
inch thick and eight inches wide. These
STRAPS hook over cast-iron blocks. which
IL turn tt on 10 the steel screws. These
screws are thirteen fee, long. with a
thread cut ten feet. aud work IL brass
nuts. These nuts are revolyed by
worm wheels OF three feet diameter.
The w0Ims have leverage arms Of
seventeen inches. The weigh, is trans
mitted from the iron structure on TO
the piles through the agency of OAK
cap-pieces. These cap-pieces are l-4l2
inches. and ruu the entire length
Of the dock over three rows Of
piles. The weight on the cap-pleces
is distributed over l32 piles. Motion
sideways IS resisted by the dock being
Traced against tweuty-four piles. There
is q row Of piles driven outside the
dock. and disconnected with IL, 70 pro-
tect the dock against sudden shocks.
il takes seveuty-tive revolutions Of the
worm wheel 20 turn the nut around
once. This advances the screw three
quarters Of al inch. Il was calculated
that when worked by man-power the
rate OF raising q vessel would be one
foot per hour. Tie actual time was a.
follows First hour tweuty-four inches
second hour. ten inches; third hour.
eight inches. OF an average OF one foot
two inches per hour. The Leverage IS
so great that the screws were worked
with the power resident II the little
finger, even when the entire weight o.
the vessel was upon the screws. The
dock Is - feet long aud thirty feet
wide II can be heightened readily,
and with additional straps can take NJ
any vessel that the depth Of water vii
allow at the locality: or. ID other
words. the dock is capable Of indefinite
extension as TO length and depth.
The amount appropriated for the con-
strucuon Of the screw dock was s2.500,
and the amount placed al my disposal
for the works Of protection e200,
making In all s2,7O0. BY an arrange
ment sanctioned by the committee the
works Of protection were executed in a
different manner from the original IN
tenuon. and the 500 were devoted to
the screw dock.
Tie total cost TO The city was as iol-
lows
Bis foi screws as per cuntract..-.sI .Z25 100
Bile ior g.rders a. ler contract. l.l4n 600
bl,ls foi strap a. per coutuct.... @-- 900
Total lccst.......................... O0
A mount appTopr.s 7Ou
Amount expended ...............-.... z.ist
Amount lef. over.....................-..-s lo7
or. the dock was completed at cost 10
TIE city Of SlQ- less than the estimates.
Owing 10 reasons that % Is unneces-
sary for Int mention here. II is de-
sired by the officer OF the United
States Engineer Corps in charge
Of the James-riyer Improvement
that the expenses Of the office in
Richmond be cut down. and according
ly after the lst Of September ! viii not
be able 10 take the active part IN the
affairs OF the river that have pre-
viOusly done In this connection il
may lot be injudicious IN me 70 suggest
that there are certain accessories 10 the
screw dock that, had remained ID &c
tive charge Of the works. might have
been able to provide for but under the
existing circumstances ! will not be
able 10 90 so. The accessories 10 which
I alludge are additional straps. certain
fxings for readily changing the worm
wheel in and out OF gear, painting the
iron. and bilge-blocks for vessels Of
curved bottom.
In turning over the screw dock to
abe committee Of which you are chair
man, hope you will allow me TO ex-
press ny qualification Of the courtesy I
have received at their hands and for
their ready acquiescence IL my plans.
] regret the necessity Of terminating my