of the car or to pass on to the next.  The length from end to end is 33 feet in the mixed cars, comprising two first-class and four second-class compartments, and 32 feet in cars of the third class, with six compartments.  The width of the compartments is 5.6 and 5 feet, according to the class.  The passageway is 28 inches in width in the mixed cars, and 24 in those of the third class.  The roof is so arranged as to afford a circulation of cool air in the interior.

[Illustration:  Fig. 2.—­PLAN.]

The application of the zigzag passageway has the inconvenience of slightly elongating the car, but it is advantageous to the passengers, who can thus enjoy a view of the landscape on both sides of the train.—­La Nature.

* * * * *

FOUNDATIONS OF THE CENTRAL VIADUCT OF CLEVELAND, O.

The Central viaduct, now under construction in the city of Cleveland, is probably the longest structure of the kind devoted entirely to street traffic.  The superstructure is in two distinct portions, separated by a point of high ground.  The main portion, extending across the river valley from Hill street to Jennings avenue, is 2,840 feet long on the floor line, including the river bridge, a swing 233 feet in length; the other portion, crossing Walworth run from Davidson street to Abbey street, is 1,093 feet long.  Add to these the earthwork and masonry approaches, 1,415 feet long, and we have a total length of 5,348 feet.  The width of roadway is 40 feet, sidewalks 8 feet each.  The elevation of the roadway above the water level at the river crossing is 102 feet.  The superstructure is of wrought iron, mainly trapezoidal trusses, varying in length from 45 feet to 150 feet.  The river piers are of first-class masonry, on pile and timber foundations.  The other supports of the viaduct are wrought iron trestles on masonry piers, resting on broad concrete foundations.  The pressure on the material beneath the concrete, which is plastic blue clay of varying degrees of stiffness mixed with fine sand, is about one ton per square foot.

The Cuyahoga valley, which the viaduct crosses from bluff to bluff, is composed mainly of blue clay to a depth of over 150 feet below the river level.  No attempt is made to carry the foundation to the rock.  White oak piles from 50 to 60 feet in length and 10 inches in diameter at small end are driven for the bridge piers either side of the river bed, and these are cut off with a circular saw 18 feet below the surface of the water.  Excavation by dredging was made to a depth of 3 feet below where the piles are cut off to allow for the rising of the clay during the driving of the piles.  The piles are spaced about 2 feet 5 inches each way, center to center.  The grillage or platform covering the piles consists of 14 courses of white oak timber, 12 inches by 12 inches, having a few pine timbers interspersed so as