openings, and extends above and below the bridge, to the extremities of the cut-waters, and on these are placed the transverse bearers of the piers. The whole of the foundation is of white deal. The following are the principal dimensions:

The castings were made at the foundry of Messrs. Dixon & Co., at Amsterdam.

The cost of the bridge was 83,000 florins (= £6916 13s. 4d.) All the details of dimensions and cost are given.

The timber bridge at Vogelenzang is built on the American trelliswork system; it is 54 metres (≈ 177 feet 2 inches English) long by 9.92 metres (= 32 feet 6 inches English) wide, and spans the high road and the canal, with its towing path, at an angle of 30° with the latter. The piers are of masonry upon piles.

The timber-work consists of three ribs of lattice-work, one on each outer side of the platform and one in the centre, between the two lines of rails. Each series consists of battens of red Riga deal, 3 inches thick and 12 inches wide, crossed at an angle of 45° with the horizon, and therefore at right angles with each other, as shown in the elevation, and well fastened at each crossing, with oak trenails. More than one-third of the depth of the lattices is below the platform; and its general stability is very much increased, and lateral vibration is prevented, by the diagonal trussing shown in the transverse section and plan of the platform. The transverse oak bearers, 10 inches square, on which the planking of the platform is laid, are placed at intervals of about 3 feet, every alternate one being trussed, as shown in the section, and the truss bound together by a pair of iron screw-bolts, 4 feet long, placed between the longitudinal bearers of the rails. The planking of the platform is of white deal, 3 inches thick and 20 inches wide; and, excepting this and the oak bearers of the platform, the whole of the timber-work is of red Riga deal.

The following are the principal dimensions of the parts:

This construction is stated to be very satisfactory, and to have cost only 46,000 florins (= £3832 6s. 8d.)

The trussed timber bridge over the Warmonder Leede, crosses the river at an angle of 50°. It has five openings of 6.30 metres (= 20 feet 8 inches English) each; through one of these, the navigation is carried on, and it is closed when the trains pass, by a sliding platform moving diagonally upon rollers, which is worked by one man, and by very simple mechanism, like that of the double platform bridge at Vink.

The heads of the piles for this bridge require to be cut off, and a tenon to be worked upon each, below the water line; this was done by a simple apparatus, consisting of a deal box, well put together and caulked, so as to be water tight; it was 2 metres (= 6 feet 6 inches English) long, 1.30 metre (= 4 feet 3 inches English) wide, and 1 metre ( 3 feet 3 inches English) deep. Through the centre of the bottom there was a hole large enough to admit the head of a pile. Around this hole was nailed the open bottom of a sack of stout canvas, strengthened with leather. Two cords were made fast, by one end of each, to the box, and the others were passed through pulleys

=

in the sides.

When a pile was required to be cut off, the box was put over it, and by weights within, it was caused to descend as low as was requisite; by means of the two cords, the lower end of the sack was then drawn round the pile, so as to form a water-tight joint; by a small pump, the water was then emptied from the box, into which a workman descended, turned back the canvas sack, and after sawing off the pile, cut the head into any desired form.

This system is stated to have been used wherever the piles were required to be cut off under water, and to have been very successful. The cost of the bridge over the Warmonder Leede was 44,600 florins (= £3716 13s. 4d.)

The trussed timber bridge, which crosses the canal and the towing path near Leyden, at an angle of 60°, is fixed, and has a span of 17.20 metres (36 feet 5 inches English.) Its cost, with some accessory works, was 34,800 florins (= £2900.)

The trussed timber bridge over the Rhine, near Vink, beyond Leyden is at an angle of S2° with the stream; it has five arches, three of which have openings of 10 metres (= 32 feet 10 inches English) each, and the two side arches are 6 metres (= 19 feet 8 inches English) each; one of these latter, which is intended for the navigation, is closed by two parallel platforms which slide diagonally in opposite directions; when opening, they are moved simultaneously by one man, with very simple machinery. The cost of this bridge was 41,200 florins (= £3433 6s. 8d.)

The single swivel bridge over the Delft canal at the Hague, is of cast iron, and spans the canal at the angle of 72°, with only one opening of 8 metres (26 feet 3 inches English.) The piers are of masonry, founded on piles. Its cost was 31,000 florins (£2583.)

The railway necessarily passes over numerous canals, whose traffic must be provided for; it was consequently requisite to provide a cheap and simple mode of crossing them; the author therefore devised a peculiar form of bridge, and has called it the "turn rail bridge."

Four timber bearers, 12 inches deep by six inches wide, carry the two lines of rails; they are jointed on to heel posts of oak, shod with iron, which turn upon centres, on plates set in the masonry of the abutment. The bearers are further supported by brackets of cast iron; and each pair is connected by two bars, turning on joints, to preserve the parallelism of the rails. Each pair opens outwards, for the passage of the boats; and when they are closed, the ends of the bearers rest in recesses, prepared in the masonry for their reception, in order that the ends of the movable rails shall coincide with those of the fixed ones. This form of bridge is very cheap, and is found to answer well for a span not exceeding 16 feet.

The population of the towns through which the railway passes, is stated thus:

A tabular statement is given of the number of travelers, and the amount of the receipts since the opening of the railway.

There is also a statement of the number of locomotives employed, their power, sizes, and number of wheels, the makers' names, the number of miles run over, with many other particulars.

A detailed statement is also given of the lengths and height, above the datum line (AP)* of every portion of the three divisions of the railway which are opened, with particulars of all the bridges and other constructions.

This communication is illustrated by a section and plan of the line of railway; a map of part of Holland; and one of the city of Amsterdam; also, a series of lithographic drawings of the bridges and other works on the line; and a model of the turn-rail bridges, to be seen in the society's library.

In a letter to the Secretary Inst. C. E., dated May 4, 1844, Mr. Conrad says: "At the last meeting of the shareholders, on the 26th April, we were authorized to borrow 2,500,000 florins (= £211,750) for finishing the fourth division of the railway, or that part between the Hague and Rotterdam. I shall therefore commence immediately the execution of the works, the plans for which I have already laid down. We expect that a new law of expropriation will be passed, and when the States General have conferred upon us that benefit, we shall see the works carried on with increased vigor.

"Since the opening of the railway, as far as the Hague, the improvement in the value of the shares has been very great; the price in December, 1843, was 56 florins, and is now from 98 florins to 99 florins; and the shares will speedily be at a premium.

"The comparison of the number of travelers and of the amount of receipts in similar months of 1843 and 1844, is curious.

"The tariff of fares is also altered to the following rate :

d.

66

First class, 5 cents per kilometre per passenger=1.66 per mile.
Second "
Third << 21

4

66

66

= = 1.33

=0.83 66

This alteration has been found very profitable, as a greater number of passengers now travel in the first class carriages."

Trans. Inst. Civ. Eng'rs.-London Jour. Arts and Sci.

• AP. (Amsterdam Pile,) a fixed water level adopted by the Government as a datum line

in all the bydraulic works in Holland.

The Hungerford Suspension Bridge.

This bridge was opened as a public thoroughfare across the Thames, from Hungerford market to Lambeth, on the 1st of May. The following particulars of the bridge, are from a lecture at the Royal Institution, delivered by Mr. Cowper in April. We extract from the Athenæum. This bridge is for foot passengers only: it consists of four broad chains, viz., two chains, one above the other, on each side of the platform; each chain consists of ten and eleven links alternately, and, near the piers, of eleven and twelve. This increased strength is to meet the increased strain which takes place near the piers. The chain of the Menai Bridge is only five links wide, and the chain of the Hammersmith only six links wide; but the great breadth of the Hungerford chain (viz., eleven links, or about two feet,) gives them great power to resist the effects of the wind, and thus to prevent vibration. Two brick piers, in the Italian style, are built in the river, over which the chains are carried, forming thus a central and two side spans.

The two piers are in height,

The central span between the piers, (being 110 feet

wider than the Menai Bridge,)

The length between the abutments,

Deflection of the chain,

80 feet.

676 feet.

13524 feet.

50 feet.

24 feet.

Length of each link, (7 in. wide, 1 in. thick,)

Weight of each link,

(The connecting pins are 4 inches diameter.) The whole number of links,

Their weight, .

Width of the platform,

near the piers,

Height above high water at the centre of centre span,

(Giving a rise of four feet in the centre. This gives
additional height for the river traffic, and produces
a graceful curve, and prevents any appearance of
swagging.)

The section of the chains at the centre of centre span is
near the piers,

54 cwt.

2600

715 tons.

14 feet.

324 feet. 284 feet.

296 sq. in. 312 sq. in. 17 tons is

A square inch of iron breaks with 27 or 29 tons, but taken as the impairing weight, i. e. the weight at which it begins to stretch; we have, therefore, for the weight the bridge will actually bear,

296 x 17 tons=5180 tons, while 296 X 5 tous=1480 tons,

is the greatest load that can be put upon it. This is taking a crowd standing close together to be 1000lb. per square foot. The entire weight of the chain, the platform, and a full load upon it, would make a load of about 1000 tons on each pier, being about S1⁄2 tons on each square foot of brick-work, or not quite 14 cwt. on each square inch. The chains are attached to large wrought-iron vertical plates