the span one hundred feet, and the spring one-sixth of the span. First, three segments of a circle, each in three pieces about thirty-six feet long, eight inches by four diameter, to be united as at A. Second, three straight bars, to extend from one pier to the other, to be of the above diameters, may also be cast in three pieces; which bars are to extend along the top of the segments to the piers, and form a line parallel to the horizon: the bars and segments to be united by perpendicular stirrups like B, ten or fifteen feet distant from each other. The mortice in the lower end of the stirrup being thirteen inches long, will be sufficient to secure the segment, and leave room for a hole two inches square, through which a cross-brace, C, is to pass, and fasten the segments at proper distances: the brace to have a mortice cast on each side of the stirrup, in order to tighten the work by wedges. On the top of the stirrup, the square hole to receive the cross-brace may be beneath the mortices, as in the figure; by which means the whole may be combined, and form an iron stage to support the troughs. The trough plates should be at least one inch thick, the side plates six feet broad, and as great a length as can conveniently be cast; which may be performed twelve feet, and perhaps more in length: the flange to be outside on these plates. The bottom plates may be six feet wide, thirteen feet long, seven feet plate, and four arms projecting, each three feet long, in order to support the horse-path and braces, as exhibited at D. Two of these plates laid across the stage, and screwed together, with a flange under, will compose a length equal to one of the side plates, which may either meet or break joint, as is thought proper. The whole may, in this manner, be screwed together on packing of wool and tar, and have the seams pitched like those of a ship. On the plates composing one side of the trough, small brackets, about three feet from the top, must be cast, as at E, in order to support the horse-path: perpendicular rails, eight feet long, being raised from the arms of the bottom plates, will sup

port the outside of the horse-path-also the iron railing, as in the section. By this mode, two patterns will answer for the whole of the trough plates, and but few will be required for the springs, rails, and spurs; while the saving in time and expense will be considerable particularly where it is necessary to bring the stone by long land carriage; for the arches being dispensed with, and the piers not more than one-third of the dimensions necessary to an aqueduct of stone, will most materially reduce the quantity of masonry.

"In aqueducts of stone, one of the great difficulties is to line and puddle so tight as to prevent the water penetrating into and injuring the masonry; but in one of iron, should a leak take place, it will instantly appear; and, on shutting the stop-gates at each end, and discharging the water, it may be stopped in a few hours, if not minutes: this circumstance in aqueducts is, perhaps, one of the greatest preservatives - they are consequently less liable to injury, and only subject to the corroding tooth of time."

A short time after this, a most stupendous work of this kind (a Fulton cast-iron aqueduct) was undertaken and completed for crossing the DEE river, in Scotland, at PONTCYSYLTEE, about twenty miles south-west of Chester; where nineteen massive conical pillars of stone, at fifty-two feet from each other, the middlemost of which is no less than one hundred and twenty-six feet in height, support between the top of every pair a number of elliptical cast-iron ribs, which, by means of uprights and horizontal bars, support a cast-iron aqueduct about three hundred and twenty-nine yards long, twenty feet wide, and six in depth, composed of massive

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sheets of cast-iron, cemented and riveted together, having on its south side an iron platform and railing for the towing-path.

It was foretold that the effects of heat and cold would destroy it, but no expansion or contraction of the metal is as yet visible; and notwithstanding the summer's heat, the winter's ice, and numerous floods, this cast-iron aqueduct still remains an evidence of Fulton's practical engineering.

Bridges.

Mr. Fulton also submitted his PLANS, DRAWINGS, and MODELS of bridges, to the British Board of Agriculture; and his different kinds of cast-iron bridges for passing railways over valleys, either level across, down one slope and up the other of the valley, or rising obliquely up: in the first and last of which he proposed to avoid any solid platform or top for carrying the horse-path, and to tow or drag the wagons over this open railway by an endless rope or chain, passing over a pulley at each end, which can be set in motion by a windlass, a descending weight, or other power. On the approach to a river or yard where considerable quantities of coals or other minerals are to be discharged, it will be proper to keep the railway upon a high level, by embankment, or on arches, or on a stage

of timber, that the wagons may be discharged from the top of a staith or stage into ships or boats, or into carts and wagons, without being moved by manual labour. Rivers, brooks, or hollow roads, must be crossed on bridges whose tops are formed to the regular slope of the plane; and where roads cross the intended railway, they must either be raised so as to be carried over, or sunk so as to pass under the same, or be made up the same height; and the rails must, in that part, have ribs of less height and greater strength, and the whole must be so firmly embedded in masonry, that the heaviest carriages, in crossing, cannot damage it.

The Board was highly pleased, and approved of Mr. Fulton's plans; and one of his bridges was erected in Wandsworth town, and at several other places on the SURREY IRON RAILWAY.

Mr. Fulton's designs fully explained the principles of his different bridges of cast-iron; also for bridges for newly settled and woody countries, wherein large timbers dowelled together supply the place of keystone, above which the platform for the road was to be supported.

He never completed a model until he had first designed and projected a perfect drawing, according to the proper scale; and for canals and railways his specifications, descriptions, and calculations, are

most remarkable for their accuracy, and quite voluminous; showing the cost of every foot of the work, its complete proportions and dimensions, the average number of tons to a horse, the rate of miles per hour, from one ton and upwards, according to the speed, and the clear amount of revenue and profits on each and every ton or article of transportation-evincing the practical knowledge of a most experienced and perfect civil engineer.

Inclined-Planes.

On the 8th of May, 1794, Mr. Fulton obtained a patent in England for the use of a DOUBLE INCLINED-PLANE, with cradles having cisterns or caissons under them, that the boats were in some cases to be taken on to the cradles sideways instead of lengthways: this was proposed to be accomplished by short Inclined-Planes, on which the boats, upon wheeled carriages, were to be dragged out of the upper and lower canals by means of ropes working on the axles of water-wheels: a brake is to be used for regulating the motion of the boats and cisterns when brought nearly to an equilibrium by the valves: brace-locks or pulleys to be used for shortening or lengthening the large ropes when necessary.

He recommended the general adoption of fords