One blueprint is too large to be scanned.
file:///X|/Special%20Collections/purgatory/Phi%20Mu/Mothershead,%20Charles/blueprint.txt[5/4/2011 10:00:56 AM]
THE HISTORY AND CONSTRUCTION Of
CABIN JOHN BRIDGE, AT CABIN JOHN, MARYLAND.
A THESIS PREPAEED
CHARLES T. MOTHEESEAD
FOR INITIATION INTO TEE
BETA CHAPTER OE MAHYLASB
OF TAU BETA PI FRATERNITY
JANUARY 15, 1932.
The facts regarding Cabin John Bridge developed in this thesis may-
be "briefly summarized as follows:
Situated seven miles west of the City of Washington, D.C., and
spanning Cabin John Creek, is a bridge which, prior to 1903, was the longest
masonry span in the world. It was built by the War Department under the
supervision of General Montgomery C. Meigs, U. S. Corps of Engineers, during
the years 1857 - 1354, and was used to carry the Washington aqueduct across the
valley at Cabin John. The bridge derives its name from a hermit called John
who lived in a cabin on the bank of the creek.
The course of construction was interrupted for a short time during
the Civil War and it was feared the arch might be destroyed, but the work was
completed without mishap.
The granite arch has a span of 220 feet and a rise of 57.26 feet.
The abutments are constructed of Port Deposit granite and blue gneiss, and the
spandrels and parapet walls are built of Seneca sandstone. The conduit
through the bridge is formed by three brick rings and has an outside diameter
of 9 feet.
In repairing the bridge it has been necessary to line the conduit
with cast iron sectional tubing, place steel tie-rods across both ends, con-
struct a new roadway, and reset the coping.
1. Records of the Columbia Historical Society, Washington, D.C,
Volume II - 1899. (An article "by Mr. Wm. T. S. Curtis read before
the Society on November 1, 1897.)
2. C a Mn John Bridge, by Alex. J. Yowell. Ihird edition 1898, W a shingtoniana
Files, Carnegie Library.
3. Cabin John Bridge, By W. H. Brewton, Washington, D.C. From files at the
4. House of Representatives - Document Kb. 1329, - Sixty-first Congress,
5. Publication of The Confederate Southern Memorial Association of ITew
Orleans, La. - 1909 (Library of Congress) .
6. The original notes of G-eneral Meigs, Chief Engineer of Washington Aqueduct,
taken from his scrapbook in the Library of the War Department.
7 Ell A E D
In presenting this Thesis, the author wishes to ac'mowl edge the
aid and cooperation rendered "by Mr. Hardy of the Delecarlia Revervoir and Mr*
McQueen of the McMillan Heservoir, without which, much of the present niaterial
would be lacking.
CABIN JOHN BRIDGE
Seven miles from West Washington, District of Columbia, better
known as Georgetown, D.C., upon what is called Conduit Road, which follows the
line of the Washington Aqueduct from the City limits to the Great Falls of the
Potomac, is a structure which enjoys and deserves the distinction of being one
of the most noted bridges of its kind in the world. This bridge, built by the
United States Government, spans Cabin John Creek. The creek is a stream of
respectable size which rises at Rockville, Maryland, flows through one of the
most beautiful sections of the state, and pours its slowly moving waters into
the Potomac a few hundred feet below the great bridge bearing its name, - a
bridge of national reknown, which enjoys the distinction of being, prior to
1902, the largest single arch span of masonry in the world.
History records but one bridge, or stone arch built before 1902
which was greater in span than that of Cabin John. This bridge spanned the
Adda, a tributary of the Po, at Trezzo, in Northern Italy and is supposed to
have been built in the year A.D. 1380, by order of the Duke of llilan, but in
the year 1427 was destroyed by the Italian General Carmagnola. It consisted
of a single stone arch of granite with a span of 251 feet, a rise of 38 feet,
and at the crown was only 4 feet thick.
Several large masonry arches have been constructed in Europe, but
none exceeded or equalled the length of span of Cabin John Bridge. The
Grosvenor 3 ridge over the River Dee at Chester, England, has a span of 200feet
and a rise of 42 feet. Within the last few years a single span stone bridge
very similar in design to that of Cabin John has been built over the River
Pruth, at Jaranese on the line of the Austrian Stanislaw, Woronieka Railroad in
- 2 -
Galicia. It has a single span of 213 feet, seven feet less than that of
At the present time, Cabin John Bridge, although not the longest
single span of masonry in the world, has not been excelled in the United States*
Its length of span is exceeded in Europe by the Sidi Kached Bridge, at Constan-
tine, Algiers, completed in 1915. This bridge has a total length of 1,468
feet, a main span of 227 feet, and a height of 300 feet. The longest masonry
arch in the world is the Plaaen Bridge, located at Plauen, Saxony. It was
completed in 1903 and has a total length of 492 feet, a single arch span of
?95^ feet, and a height of 58 feet. It was built at a cost of $125,000.
Cabin John Bridge was primarily constructed for the purpose of
carrying the Washington Aqueduct across the ravine of Cabin John Creek. Frior
to the building of the conduit, Washington depended entirely upon wells and
cisterns for the water supply. As the District of Columbia was under Federal
jurisdiction, the work of bringing into the city the additional water supply
from the Potomac at Great Falls was placed in the hands of the Corps of
Engineers of the War Department. Work was started early in 1857, and the
bridge was completed in 1864.
QHiaiN OF THE SAME "CAB III JOHN BRIDGE"
The origin of the name "Cabin John" as applied to the creek, and
likewise to the bridge which spans it, is somewhat shadowy and uncertain.
There is a story to the effect that at an early date, in the 19th century, a
mysterious character occupied a rough cabin on the banks of the creek a short
distance above the present site of the bridge. Ee is stated to have led the
life of a hermit; fishing in the stream, and hunting in the surrounding
- s -
forests. The only name he was known by was "John"; sometimes he was spoken
of as "John of the Cabin"; and also as "Captain John". Upon some of the
old records of Montgomery County, Maryland, the name of the creek is given as
"Captain John". The present name "Cabin John" is either a corruption of
"Captain John" , (of "John of the Cabin". After dwelling in his cabin by the
creek for a number of years he disappeared in the same mysterious manner in
which he came, and nothing was ever known of his fate. Proof that there was
such a mysterious character and that he lived in a cabin on the banks of the
creek which bears his name, has come from two sources ;-
1. Captain Fyles, an aged resident, who as well as his father
before him, had lived in the vicinity of Cabin John Bridge for a good many
years, stated that when a boy, he had played in and about the Cabin and had
also gathered arrow and spear heads which were nearby*
2. In the year 1825, the following lines were found under a de-
lapidated grainbin in an old mill located on the banks of Cabin John Creek:
"John of the Cabin" - a curious wight -
Sprang out of the river one dark stormy night,
He built a warm hut in a lonely retreat,
And lived many years upon fishes and meat.
When the last lone raccoon on the creek he had slain.
It is said he jumped into the river again.
As no name to the Creek liy the ancients was given,
It was called "Cabin John", after John went to Heaven.
- 4 -
The Initial step in the construction of the Washington Aqueduct
was taken on April 21, 1853, when Congress, in the appropriation act of that
date, inserted the following provision!
- To enable the President to cause the necessary surveys, projects, and
estimates to be made for determining the "best means of affording the
cities of Washington and Georgetown an unfailing and abundant supply of
good and wholesome water, report thereof to be made to Congress at its
next session, the sum of $5,000 or so much thereof as may be necessary
(10 Stat. 92). -
On March 3, 1853, an appropriation of $100,000 was made to be ex-
pended under the direction of the President of the United States for the pur-
pose of bringing water into the city (10 Stat. 306). The following addition-
al appropriations were made in the succeeding years as the work progressed;
on March 3, 1355 an appropriation of $250,000 (10 Stat. SS4) ; August 18,1856
an appropriation of $250,000; March 3, 185.7 an appropriation of $1,000,000
was made for continuing the Washington Aqueduct, and on June 13, 1858, an
additional sum of $800,000 was granted.
The first work on the Washington Aqueduct was begun in 1853 during
the administration of President Buchanan whose Secretary of Wax was Jefferson
Davis. The engineer of the aqueduct from its inception and including the con-
struction of Cabin John Bridge was Captain Montgomery C. Meigs, U* S. Corps of
Engineers. He assumed charge of the work immediately after the appropriation
of $5,000 was made in 1852, and the surveys, projects, and estimates for the
- 5 -
general system of water supply were prepared by him. Many difficulties arose
in the construction and carrying out of the original plans for the aqueduct -
valleys had to be spanned and hills had to be tunneled to provide for the
The most serious obstacle encountered was at Cabin John Hun. The
ravine was too wide and too deep to fill, and the only remaining solution was
to construct an aqueduct over the valley. At first it was decided to span it
with a bridge of masonry, supported on a series of piers and arches, at an
estimated cost of $72,409. This original plan was changed and it was deter-
mined that a bridge should be constructed to excel any of its kind on earth
and at the same time to be a lasting and imperishable monument to the genius
of its engineer and to the possibilities of modern "bridge building.
The actual work on Cabin John Bridge was started early in 185?.
Before the work was started, Captain Meigs selected Mr, Charles T. Curtis to
act as general superintendent and inspector. Ur. Curtis had had training
under Col. Thayer in the building of Fort Warren, Boston Harbor and afterwards
in connection with the Boston Aqueduct.
The work was rapidly pushed, so that on December 4, 1858, the arch
was keyed, and by July 1, 1859, the arch stones, as well as a considerable
portion of the abutments were in position. In July 1860, Captain Meigs was
detailed to Fort Jefferson, Tortugas, Florida to supervise the public works at
that place. In the latter part of February 1861, he returned and resumed
charge of Cabin John Bridge. It is of interest to note why Captain Meigs was
detailed away from the bridge at such a critical time in its construction and
also for so short a oeriod.
- 6 -
On June 25, 1860, the following provision was embodied in the
appropriation act of that date:
For the completion of the Washington Aqueduct, $500,000 to he ex-
pended according to the plans and estimates of Captain Meigs and under.
Congress by the use of the language in the act intended thus to ex-
press its approval of the work of Captain Meigs.
President Buchanan transmitted a message to Congress wherein he
complained that the clause in the act providing that the money should he ex-
pended under the superintendence of Captain Meigs, was an interference with
the prerogatives and rights of the President "to he Commander-in-Chief of the
Army and Navy of the United States" as it virtually directed that the money
could not he expended unless Captain Meigs superintended its dishureement.
The President contended he had the right to send Captain Meigs away from
Washington to any part of the Union to superintend the erection of fortifica-
tions or other public works. Thus, it was that Captain Meigs was relieved of
the charge of the aqueduct and in July 1860, was ordered to Fort Jefferson.
Puring the six months absence of Captain Meigs at Fort Jefferson, the const ruc-
tion of the aqueduct was in charge of Captain Henry W. Benhara and Lieut. James
St.C. Morton, United States Corps of Engineers, and the work was continued by
them according to the plans of Captain Meigs, which had received the sanction
Captain Meigs returned from Fort Jefferson in February 1861, and
resumed charge of the construction. Shortly afterward Civil War broke out and
considerable anxiety was felt lest the Confederates should set fire to the wood
- 7 -
centering and. so destroy the arch.. But this did not come to pass. However,
from about May 1861 until July 1863, active work on the "bridge was suspended
due to the War.
In May 1861, Captain Meigs became Quartermaster- General with his
headquarters in Washington. When work was resumed on the bridge in the
summer of 1863, the control of the Washington Aqueduct was transferred from
the War Department to the charge of Caleb B. Smith, Secretary of the Interior
Department, under a joint resolution of Congress. General Meigs, therefore
ceased to have further charge of the work. Although General Meigs was the
Chief Engineer, most of the working plans and drawings of Cabin John Bridge
were prepared by Mr. Alfred L. Hives, the assistant engineer, who was a grad-
uate of the Ecole des Ponts et Chaussces in Paris. At the outbreak of Civil
War, Mr. Rives resigned his position and went South to join the Confederacy.
After the resignation of Mr. Elves in 1861, he was succeeded by Mr. Wm. R.
Button. Mr. Hut ton is best known in connection with the construction of the
Washington Bridge over the Harlem Eiver, Hew York. When the Interior Depart-
ment resumed work on the aqueduct, Mr. Hutton was appointed Chief Engineer.
He held this position until July 1863, at which time he was succeeded by Mr*
Mr. Seymour in his annual report to the Hon. John P. Usher, Secre-
tary of Interior under date of October 1, 1863, states:
"The work, so far as executed (with exception of a portion of
the dam in the Potomac, and the water facings of the district reservoir)
has been done in accordance with the plans and specifications prepared by
General Meigs and generally under his own supervision".
- 8 -
On December 5, 1863, water was turned into the aqueduct hut it
was not until the following year that the roadway surface of the bridge was
In 1867, the charge of the aqueduct was again transferred to the
War Department under Captain D. Dub. Gaillard, and is under the supervision of
the War Department at the present time.
One of the interesting sidelights on the history of Cabin John
Bridge, relates to the erasure and restoration of Jefferson Davis 1 name on
the tablet of the west abutment.
Mr. Montgomery ffeigs, son of the late General Meigs wrote the
Washington Star as follows, September 8, 1892:
"Permit me, through your collars in the Interest of truth, to
correct the statement lately published in some newspaper, that the name
of Jefferson Davis, as Secretary of War, inscribed on Cabin John Bridge
at the time of its erection was erased by order of my father, General
Meigs. My father, referring to a similar statement published a year
or two ago, wrote a member of my family that the erasure was made without
consultation with him, without his iorowledge, and at a time when he no
longer had any nontrol whatever over the aqueduct".
After the death of General Meigs in 1892, Mr. Wm. R. Button,
former Chief Engineer of the Washington Aqueduct wrote the Star endorsing the
above newspaper clipping:
"The above clipping was sent to me from Washington some months
ago. A recent conversation with Col. Elliott, in charge of the Washing-
ton Aqueduct induces me to give facts concerning the removal of Jefferson
- 9 -
Davis 1 name from Cabin John Bridge, which it seems has "been attributed to
General Meigs, wholly without reason, he being at the time Quartermaster-
General. In June 1862, at the request of the Secretary of Interior, the
Hon. Caleb B. Smith, to whose Department the aqueduct had just been trans-
ferred, I accompanied the Secretary and a number of Members of Congress on
a tour of inspection of the aqueduct. Opposite Cabin John Bridge several
of the party walked to the bridge for a nearer view. Returning in haste,
the Hon. Galusha Grow complained that General Meigs had put Jefferson
Davis' name on the bridge. Turning to me the Secretary said, 'The first
order I give you is to cut Jefferson Davis' name off the bridge.' A
few days later I was appointed Chief Engineer of the aqueduct. Hot taking
seriously the Secretary' s remark,.' I did nothing in the matter. A week
later Mr. Robert Mclntyre, the contractor, arrived to resume work upon the
bridge, and called to pay his respects to the Secretary of Interior. The
Secretary told him that Jefferson Davis' name had been put on the bridge
and he wished he would cut if off, Mr. Mcl n tyre's first work was to re-
move Mr. Davis' name."
On February 16, 1909, President Roosevelt ordered the name of Jeff-
erson Davis restored to Cabin John Bridge ~by the War Department. Four days
later, February 20, 1909, the S e cretary of War, General Luke E. Wright, repeat-
ed this order to Ms Chief of Engineers, The entire face of the tablet was re-
moved and resurfaced without moving it from its position, and the original in-
scription, including the name of Jefferson Davis, recarved. The work was done
by J. B. Home, a stone cutter from Moss Point, Miss, for the sum of $127,75.
He began on Tuesday April 13, 1909, and completed the work on Friday May 14,
- 10 -.
1909. The tablet Is five feet high and, eleven feet long.
Shortly before he was ordered to Port Jefferson, Captain Meigs, be-
ing apprehensive lest some action might he taken looking to hie removal, and
desiring to perpetuate his own naroe as Chief Engineer of the bridge, caused the
following inscription to be cut in deep, imperishable letters upon two of the
arch stones near the east abutment:
M. C, Meigs,
A. D. 1859
In the Spring of 1861, the following inscription was cut upon the
tablet in the east ahutment:
Chief Engineer - Captain Montgomery
C. Meigs, U. S. Corps of Engineers,
Cabin John Bridge, in the Official B e cords of the War Department, is known as
Union Arch, by reason of having been constructed "by the Union Corps of Engineers
and during the Civil War.
luring the absence of Captain Meigs at Fort Jefferson as previously
mentioned, Lieut. Morton caused his own name and that of Captain Benham to be
cut on the face of two of the arch or ring stones near the east abutment imme-
diately under the name of Captain Meigs,' which had been inscribed there previous-
ly. Upon his return in February, 1861, Captain Meigs, observing what had beer,
done, directed that their names should be erased contending that he was Chief
Engineer, and that it was improper for their names to appear on the bridge as
Chief Engineers, particularly as they had merely carried out his plans. This
order was carried out and the erasures are still visible on the arch stones.
- 11 -
Cabin John Bridge was "bfu.il t mainly of Seneca sandstone, 'blue gneiss,
^nincy granite and hard well-burned brick laid in cement mortar. In order to
provide for the transportation by water of the stone and other materials, a
large dam was built across Cabin John Creek a short di stance above the Chesa-
peake and Ohio Canal, and a lock was constructed at that point to permit the
boats to be floated into the pond which at that time filled the valley beneath
the bridge. The contract for the cut stone for the arch was given to Frederics
and Field of Quincy, Mass., and called for the delivery to be completed by June
30, 1858. The granite was shipped to G-eorgetown by vessels, and thence to the
bridge by way of the Chesapeake and Ohio Canal,
The first work on the bridge proper began early in 1957. The soil
was removed until rock foundation was reached, and this rock in turn was blast-
ed away until the solid ledge of the hill was exposed. All disintegrated por-
tions of the ledge were removed, the surface smoothed off, and a proper face
made for the reception of the arch by a bed of cement and broken stone. The
abutments below the spring line were constructed of dressed Port Deposit granite,
and the abutment walls were of rock faced ashlar with rubble backing. The cut
stone arch was backed by a rubble arch of gray Seneca sandstone flagging* in
slabs not more than ten inches thick, and laid radially to the arch. The con-
tract for quarrying and cutting the stone in the United States quarry at Seneca,
Maryland was given to H* L. Sallaher. The spandrels were constructed of rock
faced ashlar and also had a rubble backing. The abutments and spandrels were
built hollow with relieving arches and piers in the center. The abutment
- 12 -
walls "below the water table were built of blue gneiss. All the remainder of
the face work, the arched backing, the water table, and the platform were con-
structed of Seneca sandstone. The backing of walls was done with blue gneiss
quarried at the site of the bridge* The platform or roof of the bridge was
constructed of slabs of Seneca gray sandstone, nine inches in thickness and
two and a half to four feet in width, cut and laid according to the drawings
with close joints, and secured by dowels and cramps at the ends and sides.
Grooves were cut on the upper surface to carry off the water from the joints.
The conduit through the bridge was constructed of brick.
As the super structure was very massive, it required a corresponding-
ly heavy wood centering to support it during construction. This structure
rested upon a series of stone piers, which piers still remain. In addition to
the rnain centering a further framework was constructed to carry a system of
travelling cranes by which means the stone was transported to various portions
of the structure as it was used. The remains of the piers carrying this frame-
work for the cranes can also be seen in the valley, just outside of the lines
of the bridge.
From 1864 to 1872, the only protection for pedestrians and vehicles
was a low wooden goard-rail constructed of logs and timbers. The present para-
pet walls of red Seneca sandstone were built between 1372 and 1873.
The dimensions of the bridge are as follows;
length - 450 feet over all, including abutments.
Length of span - 220 feet.
Else - 57.26 feet.
- 13 -.
Radius of intrados - 134.285 feet.
Radius of extrados - 143.269 feet.
Thickness at crown - 4.2 feet.
Width - 20.4 feet.
Diameter of conduit - 9 feet.
Surface of roadway above ravine - 100 feet.
The arch or ring stones are each 2 feet thick, 4 feet deep at the
crown and 6.2 feet at the spring line.
There are 11,914.8 cubic yards of masonry, 352.66 cubic yards of
concrete, and 516 yaards of brickwork used in the construction of the bridge.
The total cost including the parapet walls was $254,000.
PRESEBVATION AND REPAIR OF CABIF JOHIT BRIDGE
In a letter written on January 28, 1911 by C. D. Hilles, acting
Sgcretary of the Treasury, to be presented before the House of Representatives;
the matter of the preservation and repair of Cabin John Bridge is introduced
"I have the honor to transmit herewith, for the consideration of
Congress, copy of a communication of the president of the Board of Commissioners
of the District of Columbia, of this date, submitting an urgent estimate of
appropriation recommended by the Chief of Engineers, U.S. Array, and transmitted
through the Secretary of War, required for the Washington Aqueduct for the
preservation and repair of Cabin John Bridge, $35,000 of which the sum of
$20,000 is to be immediately available -
The necessity for the appropriation can be explained by excerpts
taken from a letter writtin by W. C. Langfitt, Chief of Engineers, TJ. S. Army,
Washington, D.C., on January 21, 1911.
- 14 -
" - When the water was first admitted to the conduit from Great
Falls in 1863 a number of leaks were found in the Cabin John 3ridge when there
was about seven feet of water in the conduit which is nine feet in diameter.
The water was drawn off, the lower half of the conduit plastered, and after the
water was again admitted no leakage was observed; the flow being below the
upper limits of the plastered section. As the consumption of water in the city-
has increased, requiring the extension and raising of the dam at Great Falls,
the conduit has been running fuller. As the amount of water passing through
the conduit increased, the upper portion of the conduit through the Cabin John
Bridge not having been plastered, it was discovered that the mortar between the
bricks had worn away to a depth of one inch in some places, and the leakage be-
gan again. In 1905, the interior was carefully cleaned and all cracks were
filled with cement mortar. Thus about 90 per cent of the leakage was stopped.
In 1908 the complete plastering of the upper portion of the conduit was commenced
and by 1909, 134 feet of the conduit through the bridge had been plastered com-
pletely with Portland cement mortar. The work was finished late in 1910 and
stopped the leakage in the center of the bridge, but did not affect the leakage
between the center and the ahutmBnts" ,
"During inspection, long cracks in the masonry of the conduit were
noted, on both sides of the center, the axis of the bridge lying almost due east
and west. These joints were kept carefully filled with mortar and it was felt
assured that most of the lea ka ge did not come through the joints of the brick
crown of the conduit. These long cracks lie in the lower quadrant on the
north side and undoubtedly have been caused by unequal expansion of the two
sides of the bridge, the south side being exposed throughout the day to the
direct rays of the sun and the north side always in the shade. This unequal
- 15 -
expansion has broken the three brick rings of which the conduit is constructed,
along the length of the cracks, and the upper quadrant of the ring is moving
over the lower quadrant at the rate of l/8 inch a year by recent measurments.
As the masonry of the bridge contracts during cold weather, the cracks in the
conduit open up, the extent of opening depending upon the degree of cold. It
has been estimated that the leakage of water through the masonry of the bridge
in December, 1910 was not less than 2,000,000 gallons per day. The maximum
capacity of the conduit is 90,000,000 gallons per day."
"It is proposed to place within the bridge a metal lining either of
steel or iron tube 8 feet six inches in diameter, surrounded by concrete, or by
placing of cast iron sectional lining 8 feet in diameter, similar to that used
in the Washington Aqueduct tunnel under Eock Creek. Either method would be
satisfactory and render the bridge water- tight, thus preventing the disintegra-
tion of the masonry in the faqe of the bridge caused by the freezing of water
in the joints and interstices."
These recommendations for preservation and repair were endorsed by
W. H. Bixby, Chief of Engineers, U> S. Array and J» M. Dickinson, S e cretary of
War. Commissioners of the District of Columbia, Amo H* Rudolph, John A. John-
ston, and W. V. Judson transmitted to the S e cretary of Treasury, Hon. Frank: l!c-
Veagh, an estimate of appropriation of $35,000 needed for the Washington Aqueduct,
for the District of Columbia for the fiscal year ending June 30, 1912, along
with a letter bearing the President's approval. The result was the letter
read before Congress written by C. D. Hi lies, acting S e cretary of Treasury. The
appropriation was approved by Congress on March 2, 1911, The recommended re-
pairs were completed and consisted of a cast iron lining through the bridge,
- 16 -
steel tie rods across "both ends, a new roadway, and a reset coping. The old
brick roadway over the "bridge was replaced with asphalt blocks by contract for
$2,012.40. In order to make this surface impervious to water, it was treated
wi th Tarvia A.
Years have cone and gone since the completion of the bridge, and
still it is as solid and immovable as the hills upon which it rests, and, as so
aptly inscribed on the abutment, - esto perpefrua - it will live forever and r e-
main for the eyes of generations yet unborn, a momument to the genius and in-
spiration of its engineer, Montgomery C. Meigs.
CABIN JOHN BRIDGE
Span * BW
"mwWftffltf f iff ft f /.-// r :
SCALE, OP FEET
HOR. SECTION C"D
Construct ion Commented tB57
Const r uchon Completed 1304
Parapet Watts Constructed I87HS73
Cut Stone Arch-(juwcy Granite
ffubble Arch- Seneca Sandstone
Spandnk- Seneca Sana's font
Parapet Walls- Sen&CQ Sandstone
Abutments - Gneiss from Montgomery Co, Md.
SECTION AT KEY
SCALE OF FEET
Tablet on East abutment
Tablet on West abutment
Remains of dam built to float boats into pond under
Part of lock at dam
Iron door leading to interior of
afcutment and spandrel