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To the President and Directors of the Alexandria Canal Company:

GENTLEMEN: . In compliance with your request, and by permission of the Board of Directors of the Chesapeake and Ohio Canal Company, I have made an examination, accompanied by Wilson M. C. Fairfax, Esq. civil engineer, of the several routes of your canal, as located by him. Commencing in the city of Georgetown, the Alexandria canal is to cross the Po. tomac by the proposed aqueduct, which is to be 1500 feet long, as located, about 100 yards above Mason's ferry. The roads from Mason's ferry and from Mason's island are to pass under the canal, through an arch, to the west side, and from thence to continue on the same side of the canal to the city of Alexandria. But little improvement can be made in the location as now made, from the point of divergency from the main canal in Georgetown, for the first three miles, nearly. At a point on Mr. Custis's land, a few hundred feet above Gravelly run, on the 5th section, two routes present; and from thence the lines diverge, and form two distinct routes for nearly three miles, one being located on the west, and the other on the east side of the Washington and Alexandria turnpike road, and each continuing on the different sides of said road, until crossing the Four Mile run, and south of which the west line crosses to the east side of said turnpike road; and both lines converge into one on the tenth section.

And having viewed the peculiarities of each line, thus located between the points above mentioned, and considered the calculations thereon, we have come to the following conclusions:

That the western line, although about 400 feet the shortest, presents much the greatest quantity of deep cutting which cannot be advantageously used in the embankments; and, as the cutting is much deeper, a greater proportionate hazard and expense may be expected from meeting with unseen rock, quicksands, and clay-slips, to all which such deep cuttings are more or less liable. And the western route also presents a greater inconvenience and additional expense of conducting the Four Mile run and Washington turnpike road under the canal, and the Columbia turnpike road over it.

On the eastern route, all these difficulties appear to be much reduced, and can be more economically surmounted. On this, there is but a small quantity of deep cutting which cannot be beneficially used in forming the adjacent embankments; and the canal being located along and near the margin of a slope, can be more conveniently drained in wet weather; and the Washington and Columbia turnpikes, near their present junction, are to pass through road arches (the ground being very conveniently situated for that purpose) under the canal; and the large culvert for the Four Mile run can be more conveniently and economically constructed than on the western line. These are the principal reasons, among others of some importance, which induce us to prefer the eastern line throughout, as being the cheapest and much the handsomest line of canal.

From the point of convergency on the tenth section, abovementioned, the line of the canal will be continued, by a beautiful combination of curves of large radii, and of straight lines, to the termination of the present examination, near the intersection of Oronoco and Pitt streets, in the city of Alexandria.

The length of this line of canal, from the main canal in Georgetown, (in. duding the aqueduct across the Potomae,) is 71 miles, to its proposed ter

mination at the Alexandria wharves; and as it is nearly two miles shorter than that located and reported by Judge Geddes, it may be satisfactory to state wherein the difference is made. The line by Judge Geddes (for economical purposes) crossed the Washington and Alexandria turnpike road twice before he arrived at the Four Mile run: the line was continued up the north side of the Four Mile run to near the head of the sheet of water, and then crossing over to the south side, and returning nearly parallel to the north side, and again crossing the said turnpike road, fell into the present route. Å line so extremely meandering and unsightly is shortened nearly twenty-five per cent. by the location herein recommended, which may be better compared by viewing the maps herewith presented.

This canal, as an important portion of the Chesapeake and Ohio canal, will complete the commercial thoroughfare between the cities of Alexandria, Georgetown, and Washington; thus forming these cities, as it were, into one great commercial depot. It is therefore highly important that the same depth and section of water should be preserved as in the main canal, which will secure to the city of Alexandria equal advantages of navigation, and of the surplus water, with the two other cities of the District.

That the supply of water for these canals will be amply sufficient for an extensive commerce, and will afford also an abundant surplus for other purposes, cannot be doubted, when it is considered that the Chesapeake and Ohio canal, as located, and nearly completed, has the full command of the waters of the Potomac at no less than three dams, now constructing across that river between Seneca and Georgetown, a distance not exceeding twenty-five miles. And when said dams are completed, and the banks of the canal become saturated, and all the works connected thereto are in complete order, it is believed that a small portion of the river taken in at Seneca dam, and at the High Falls dam, will be found amply sufficient for all the commerce of the canal, together with the expense of absorption and evaporation, quite to Georgetown and Alexandria, as both cities are on the same level, and will require no lockage water between them.

Admitting this view to be correct, it is reasonable to state that a quantity of surplus water equal to the whole quantity that can be drawn from the Potomac dam at the head of the Little Falls, through the canal, to Georgetown and to Alexandria, (being on the same level,) may, within a short time, be calculated upon as a power applicable to mechanical purposes; and as the sur. face of the canal is thirty-five feet above common high tide, and within a fèw feet of the highest parts of the city of Alexandria, a small portion of this surplus water may be conveniently conveyed from the canal to reservoirs, and thence to hydrants, for the great accommodation and safety of all parts of the city, especially in cases of fires.

Other portions of this surplus water would afford a power which, under a fall of 35 feet, * might be applied advantageously to various manufacturing purposes, and would, no doubt, be improved by enterprise and capital, and render important benefits, not only to the city of Alexandria, but to an extensive section of adjacent country.

The dimensions of the Alexandria canal are as follows, viz: The aqueduct over the Potomac is to be constructed with stone abutments and piers; the superstructure, of timber and iron; the water way, or passage for boats,

• The surface of the Chesapeake and Ohio canal above the foot of the four locks in Georgetown is 38.33 feet above low tide, and 35 feet above high tide; allowing the tides to rise 3.33 feet on the ayerage.

is to be 16 feet wide at botton, 15 feet at top, and 5 feet deep. The canal, from thence to the Four Mile run embankment, is to be in no place less than 32 feet wide at bottom, 50 feet at top, and 6 feet deep: at the embankment of Four Mile run, to be reduced to 18 feet bottom, 36 feet at surface, and 6 feet deep: after passing said embankment, to be enlarged, so that no part of the canal shall be of less dimensions than 42 feet at bottom, 60 feet at top, water line, and 6 feet in depth; and thus continued to its termination in Alexandria. The height and dimensions of the towing path and berm banks are to be the same in all respects as on the Chesapeake and Ohio canal; and there are to be no locks on this canal between Georgetown and Alexandria.

The following statement shows the length of each section, together with the amount of the grubbing, the excavations, and embankments, the number of culverts, road arches, and bridges, and such other expenses as are neces. sary in forming the canal, with the estimated price affixed, and the total cost of each, commencing at Georgetown, and ending at or near the site of the Alexandria basin.

The Potomac aqueduct, length 1,714 feet to the ends of wings. This has been variously estimated, but it is proposed to state here (a sum within ten per cent. of) the probable cost. .

. $140,000 00

The cost of the aqueduct is intended to include the foundations of the abut, ments and piers, the masonry, the superstructure, the sheet piling or planking, and puddling at each end, and the embankment at each end, as far as the ends of the wings of the abutments, where it connects with the banks of the canal, and about 92 yards of stone placed close around the edges of the foundations of each pier, and 46 yards next the face of each abutment and wings, to prevent the water from forming strong currents and undermin. ing the foundations.

First sectionLength 2,400 feet.

whole section cubie yardshiegards,

3,928 00

Extending from the south abutment of the aqueduct to No. 25, General: Mason's land. Grubbing, small cedar, pine, and oak; soil, sandy clay, and considerable rock. Grubbing and clearing the whole section

- $150 00 Excavation of earth among rocks, 7,152 cubic yards, at 12 cts. 858 24 Excavation of rock (including a little loose) 4,910 cubic yards, at 80 cts. -

3,928 00 Embankment, paid as excavation, moved 400 feet, 2,230 cubic yards, at 5 cts. -

111 50 Embankment, not paid as excavation, moved 400 feet, 40, 128 cubic yards, at 14 cts.

5,617 92 A culvert for the roads approaching Mason's ferry, (double arch,) 715 cubic yards, at $4

2,$60 00 Slope paving near culvert, made of stone already paid for as excavation, 148 yards, at 30 cts. .

44 40

$13,570 06

Second section-Length 2,700 feet. . Extending from No. 25 to No. 52, ending on Mr. Custis's land. Small pine and cedar; soil, sandy clay, and some granite rock. Grubbing and clearing the section

$50 00 Common excavation, 25,103 yards, at 11 cts.

- 2,761 33 Excavation of solid rock, requiring blasting, 488 yards, at 90 cts.

439 20 Embankment, not paid as excavation, moved 500 feet, 8,956 yards, at 15 cts.

1,343 40 A road culvert for General Mason's land, 364 yards, at $4, - *1,456 CO Blasting away rock to prepare road and deepen the way under

the culvert, 80 yards, at 90 cts. - - - - 72

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Third sectionLength 2,700 feet. Extending from station No. 52 to No. 79, ending opposite Mr. Custis's houses. A few scattering cedar and other small trees; soil, sandy loam, and clay, with gravel. Grubbing and clearing the section

$20 00 Common (shallow) excavation, 20,286 cubic yards, at 11 cts. 2,231 46 Common (deep) excavation, 17,318 cubic yards, at 14 cts. - 2,424 52 Embankment, paid as excavation, and moved 400 feet, 1,760 cubic yards, at 4 cts.

70 40 Embankment, paid as excavation, moved 300 feet, 4,494 cubic yards, at 3 cts.

134 82 Esnbankment, not paid as excavation, moved 200 feet, 4,911 cubic yards, at 13 cts.

638 43 Embankment, paid as excavation, and moved 800 feet, 17,318 cubic yards, at 8 cts.

1,345 44 Embankment, not paid as excavation, and moved 400 feet, 9,000 cubic yards, at 14 cts.

1,260 00 1 culvert of 6 feet chord, containing 469 yards, at 84 12 or 3 1,932 28 Excavation of culvert pit, 361 yards, at 12 cts.

43 22

$10,140 57

Fourth sectionLength 2,643 feet. Extending from Mr. Custis's office to near Gravelly run. S oil, sandy loam and clay. Grubbing and clearing locust trees, &c.

$15 00 Common excavation, 29,208 cubic yards, at 11 cts.

3,212 88 Embankment, paid as excavation, and moved 500 feet, 14,978 cubic yards, at 5 cts.

748 90 Culvert for Mr. Custis's farm road, 581 cubic yards, at $4 . 2,324 00 Excavation of culvert pit, 482 yards, at 10 cts.

48 20

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Perhaps the land between the canal and river may be purchased at less than this sum, as the slip is very narrow, though a small culvert would be still necessary.

Fifth section-Length 2,700 feet. Extending from No. 106 to No. 134, on Mr. Mason's land. Soil, gravelly clay and saħdy loam: favorable excavation. Grubbing and clearing scattering trees

$20 00 Common excavation, 36,468 cubic yards, at 11 cts. .

4,011 48 Embankment, paid as excavation, and moved 200 feet, 635 cubic yards, at 3 cts.

19 05 Enibankment, paid as excavation, and moved 500 feet, 1,987 cubic yards, at 5 cts.

99 35 Embankment, paid as excavation, and moved 600 feet, 15,642 cubic yards, at 6 cts.

938 52 Embankment of earth, not paid as excavation, and moved 600 feet, 19,318 cubic yards, at 17 cts.

3,284 06 @ulvert over Gravelly run, 8 feet span, contains 972 cubic yards, at $4 25, -

4,131 00 Excavation of pit for the above culvert, 296 cubic yards, at 12 cts.

35 52

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Sixth section-Length 2,100 feet. Extending across the Washington, and Alexandria, and Fairfax turnpike roads, from No. 134 to No. 155. Soil, loam and clay, with gravel. Grubbing and clearing, preparatory .

$15 00 Common excavation, 19,831 cubic yards, at 11 cts. - • 2,181 41 Embankment, paid for as excavation, and moved 400 feet, 11,322 cubic yards, at 4 cts.

452 88 Embankment, paid for as'excavation, transported 200 feet, 3,292 cubic yards, at 3 cts.

98 76 Embankment, not paid as excavation, transported 500 feet, 20,765 cubic yards, at 14 cts. ..

- 2,907 10 A road culvert of 2 arches of 10 feet span each, for the pass

age of the Washington and Columbia turnpike roads, 772

yards, at $4, - - - - After giving a proper direction of said roads to the arches, extra work in gravelling them anew, &c.,

150 00 A farm bridge for accommodation of Mr. Mason, .

500 00

sine passione 3,088 OC

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Seventh sectionLength 3,000 feet. Extending from No. 155 to No. 185. Grubbing, thick pines whole sec. tion; soil, loam and gravelly clay, stony. Grubbing and clearing the section, thick pines,

- $ 150 00 Common excavation, a little stony, 30,668 cub. yds. at 12 cts. 3,680 16 Embankment, paid as excavation, and transported 400 feet, 12,037 cubic yards, at 4 cents, -

* 481 48 Embankment, not paid as excavation, and transported 400 feet, 17,151 cubic yards, at 14 cents,

2,401 14

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