The Sudbury conduit, of Boston Water-Works, is sixteen miles long, with a grade of 1.056 feet per mile. The top is a semicircle of nine feet diameter, and the bottom is an arc of 13.22 feet radius, struck from a center 5.53 feet above the crown of the arch. The sectional area is 56.75 square feet. The foundation is of concrete; the side walls and spandrel backing of rubble stone masonry; the lining of brick, four inches thick, and the arch of brick, twelve inches thick. The Charles River is crossed by a granite bridge, 475 feet long and 75 feet high, with two segmental and five semicircle arches.
On the line of the Vanne conduit there is an aqueduct made entirely of “beton,” which spans the valleys and quicksands in the great forest of Fontainebleau, between La Vanne River and Paris.
CONDUIT DATA.—(From Fanning.)
| Locality. | DEPTH OF | HYDRAULIC | SINE OF | ||
| WIDTH | HEIGHT | WATER | MEAN | INCLINATION OF | |
| IN FEET. | IN FEET. | IN FEET. | RADIUS. | WATER SURFACE. | |
| Cochituate, Boston | 5. | 6.333 | 6.333 | 1.417 | .0000496 |
| Croton, New York | 7.47 | 8.458 | 6.083 | 2.341 | .00021 |
| Washington | 9. | 9. | 3.465 | 1.873 | .00015 |
| Brooklyn | 10. | 8.667 | 5. | 2.524 | .0001 |
| Sudbury, Boston | 9. | 7.667 | 5.3 | — | .0002 |
| Baltimore | 9. | 9. | — | — | — |
| Loch Katrine, Glasgow | 8. | 8. | 6.85 | 2.525 | .0001587 |
| Canal of Isabel III, Mad. | 7.052 | 9.184 | — | — | — |
| Vanne, Paris | 6.6 | 6.6 | 5. | — | .0001 |
| Dhues, “ | 2.3 | 3.5 | — | — | .0001 |
| Pont du Gard, Nismes | 4. | — | 3.333 | — | .0004 |
| Pont Pyla, Lyons | 1.833 | — | 1.833 | — | .00166 |
| Metz | 3.167 | — | 2.167 | — | .001 |
| Locality. | VELOCITY | COEFFIC- | DAILY DELIVERY | TOTAL DAILY |
| PER SECOND | IENT M. | AT GIVEN DEPTH, | CAPACITY, | |
| IN FEET. | U.S. GALLONS. | U.S. GALLONS. | ||
| Cochituate, Boston | 1. | .00452 | 16,398,000 | 16,500,000 |
| Croton, New York | 2.218 | .00643 | 59,340,000 | 100,000,000 |
| Washington | 1.893 | .00505 | 27,560,000 | 100,000,000 |
| Brooklyn | — | — | — | 70,000,000 |
| Sudbury, Boston | — | — | — | 70,000,000 |
| Baltimore | — | — | — | 170,000,000 |
| Loch Katrine, Glasgow | 1.7126 | .00876 | 60,000,000 | 60,000,000 |
| Canal of Isabel III, Mad. | — | — | — | 52,000,000 |
| Vanne, Paris | — | — | — | 23,500,000 |
| Dhues, “ | — | — | — | 5,500,000 |
| Pont du Gard, Nismes | 2. | — | — | 14,000,000 |
| Pont Pyla, Lyons | 2.95 | — | — | — |
| Metz | 2.738 | — | — | — |
DAMS.
The disastrous failures of earth dams has excited suspicion as to the stability of such structures; but when we consider the immensity of the dams in India, our concern should be only for the care and attention given to their construction. There the material used is well puddled; then a drove of cattle is turned loose on the fill, to stamp the earth thoroughly. This method is repeated in layers until the required height is reached. Often the Sepoys do the stamping.
The Veranun reservoir dam is twelve miles in length; and the amount of earth, of which it is composed, will encircle the globe with a belt six feet in thickness.
There is a dam on the island of Ceylon made of huge stone blocks strongly cemented together and covered over with turf, making a solid barrier of fifteen miles in length, one hundred feet wide at the base, sloping at top to forty feet, and extending across the lower end of a spacious valley.
DIMENSIONS OR RESERVOIR DAMS.—(From C. H. Beloe.)