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Having been dismembered of its nuisances, London, Bridge at present affords a conclusive proof of national improvement; and when an inhabitant of London reflects on the absurd idea of a street upon a bridge, without wondering that his ancestors should, for ages, voluntarily obstruct their only communication from shore to shore? What must have been the thronged passage for carriages, horses, and pedestrians, saved from a space of forty feet, incumbered by buildings, and the weight pressing upon the piers and arches!

Although the revenues of the structure were considerable, the demands for constant repairs were more so; and the embarrassments arising from this circumstance, added to those attending the difficulties and dangers, occasioned by a vast increase of population and trade, rendered repeated applications to the legislature necessary *.

London Bridge forms one grand street across the river, having on each side a broad foot pavement, and a massy stone balustrade, at once affording safety to the passenger, and extensive views of the river and country. These are supported by nineteen strong arches; but on account of the heavy fall of water, occasioned in a great degree by the broad sterlings, and the contracted space of free water way, many accidents have happened, and the obstruction to the navigation of the river has been considerable. Such cogent reasons have induced the interference of the city and the legislature; several plans have been suggested for the removal of the present bridge, and building another.

The present structure is nine hundred and fifteen feet long, and forty-five broad; but the widest arches, except the centre, are only twenty feet wide. Two of those arches, on the London side; and one on the Southwark side, are filled by the machinery of

THE WATER WORKS.

Having in our first volume + given an account of the invention of this great undertaking, and its history, to the year

* Malcolm's Londinium Redivivum.

VOL. D. No. 41.

S s

+ P. 150.

1701,

1701, when the proprietors were formed into a company, as they at present, continue, we shall in this place describe the properties of these wonderful pieces of machinery, in the language of the late learned Dr. Desaguliers:

"The wheels placed under the arches are moved by the common stream of the tide-water of the river Thames. The axle-tree of the water wheel is nineteen feet long, and three feet diameter; in which are four sets of arms, eight in each place, whereon are fixed four rings on sets of felloes, twenty feet in diameter, and twenty-six floats, fourteen inches long, and eighteen inches deep.

"The wheel lies, with its two gudgeons or center pins, upon two brasses, fixed on two great levers, whose fulcrum or top,, is an arched piece of, timber, the levers being made circular on their lower sides to an arch, and kept in their places by two arching studs, fixed with a sock through two mortifes in the lever.

"By these levers the wheel is thus made to rise and fall with the tide the levers are sixteen feet long, that is, from the! fulcrum to the gudgeon of the water wheel six feet, and thence to the arch ten feet. To the bottom of this arch is fixed a strong triple chain, made like a watch chain, but the links are arched to a circle of one foot diameter, having notches or teeth to take hold of the leaves of a pinion of cast iron, ten inches diameter, with eight teeth in it, moving on an axis. The other loose end of this chain has a large weight hanging at it, to help to counterpoise the wheel, and to preserve the chain from sliding on the pinion. On the same axis is fixed a cog-wheel, six feet in diameter, with fortyeight cogs; to this is applied a trundle or pinion of six rounds or teeth; and upon the same axis is fixed another cog-wheel of fifty-one cogs, into which a trundle of six rounds works, on whose axis is a winch or windlass, by which one man with the two windlasses raises or lets down the wheel, as there is occasion.

"By means of this machine, the strength of an ordinary man will raise about fifty tons weight. But, besides these levers and wheels, there is a cog-wheel eight feet diameter,

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fixed near the end of the great axis, and working into a trundle of four feet and a half diameter, and twenty rounds; whose axis or spindle is of cast iron, four inches diameter, and lying in brass at each end: a quadruple crank of cast iron, six inches square, each of the necks being turned one foot from the center, which is fixed in brass at each end, in two head-stocks fastened down by caps. The end of one of these cranks is placed close abutting to the end of the axle-tree last mentioned, and fixed thereunto by an iron wedge drove through a slit in them both for that purpose. The four necks of the crank have each an iron spear or rod fixed at their upper ends to the respective lever, within three feet of the end; which levers are twenty-four feet long, moving on centers in a frame, at the end of which are jointed four rods, with their forcing-plugs, working into four iron cylinders, cast four feet three quarters long, seven inches bore above, and nine below, where the valves lie, fastened by screwed flanches over the four holes of a hollow trunk of cast iron, having four valves in it, just at the joining-on at the bottom of the barrels or cylinders, and at one end a sucking pipe or grate, going into the water, which supplies all the four cylinders alternately.

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"From the lower part of these cylinders come out necks, turning upwards arch-wise, whose upper parts are cast with flanches to screw up to a trunk; which necks have bores of seven inches diameter, and holes in the trunk above, communicating with each of them; at which joining are placed four valves. This trunk is cast with four bosses, or protuberances, standing out against the valves, to give room for their opening and shutting; and on the upper side are four holes stopped with plugs, which take out, on occasion, to cleanse the valves. One end of the trunk is stopped by a plug; and iron pipes are joined by flanches to the other end, through which the water is forced up to any height or place required.

"Besides these four forcers, there are four more placed at the other ends of the levers, which work in the same manner, with rods and cylinders, as above. And the same works are

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repeated

repeated at the other end of the water-wheel, viz. a cogwheel, a trundle, a spindle, a crank, sucking-pipes, four levers, eight forcing-rods, eight cylinders, &c. four trunks, and two forcing-pipes: so that one single wheel works sixteen pumps.

"In the first arch next the city, is one wheel with double work of sixteen forcers. In the third arch, where the first wheel has double work at the one end, and single at the other, there are twelve forcers: the second wheel, placed in the middle, has eight forcers; and the third wheel sixteen forcers. In all fifty-two forcers.

"One turn of the four wheels makes one hundred and fourteen strokes; and when the river is at best, the wheels go six times round in a minute, and but four and a half at middle water; so that the number of strokes in a minute are six hundred and eighty-four; and as the stroke is two feet and a half in a seven inch bore, which raises three ale gallons, they raise two thousand and fifty-two gallons in a minute; that is, one hundred and twenty-three thousand one hundred and twenty gallons, or one thousand nine hundred and fifty-four hogsheads in an hour, which is at the rate of forty-six thousand eight hundred and ninety-six hogsheads per day, to the height of one hundred and twenty feet, including the waste, which may be settled at a fifth part of the whole."

Returning from the bridge, the most striking object is

THE MONUMENT.

This is a noble fluted column, erected by order of parliament, in commemoration of the burning and rebuilding of the city, after its destruction by fire in the fatal year 1666.

It was designed by Sir Christopher Wren, and is of the Doric Order; its altitude is two hundred and two feet from the ground, the greatest diameter of the shaft (or body) of the column is fifteen feet, the ground bounded by the plinth or lowest part of the pedestal twenty-eight feet square, and. the pedestal is in altitude forty feet, all of Portland stone; within is a large stair-case of black marble, containing three

hundred

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