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north side of the docks; but nothing was done till 1870, when the Clyde trustees obtained an act for enlarged docks &c., and the railway company an act for the renewal of the site of the station.

Under their act the Clyde trustees purchased additional ground, to enable them to carry out the works now authorized. The large cartoon plan showed the general outline of the docks and the diversion of the l'ointhouse Road &c. The road is 55 feet wide, and extends from Sandyford Street to Stobeross Street, or a length of 989 yards; it has been formed entirely in cutting, the average depth being 29 feet, the greatest depth 43 feet, and the total quantity removed was nearly 300,000 cubic yards, of which about a fourth was boulder-clay. Only the immense power of dynamite enabled this to be removed. The cost of the road, including land, was about £45,000.

The docks will be tidal, and, when complete, will afford 334 acres of water space 20 feet deep at low water, and will comprise three basins. The entrance from the river is at the west end of the docks, and is 100 feet in width, communicating with an outer basin 695 feet wide at its widest part, and two inner basins, 270 feet and 230 feet wide respectively, the pier between being 195 feet wide. The total area of quay space will be 27 acres, and the length of quays about 3342 yards. The entrance will be spanned by a swing bridge, worked by hydraulic power, and capable of carrying a rolling load of 60 tons. There will also be four coalingcranes, each capable of lifting 20 tons, also worked by hydraulic power. The bridge, cranes, and the necessary hydraulic machinery are being constructed by Sir W. G. Armstrong & Co. The quays will also be provided with sheds, grainstores, &c., and lines of rails.

From the borings made on the line of the quay-walls, it was ascertained that the strata were of the worst possible kind in which to construct such works, consisting as they do (excepting at the north-west corner, where boulder-clay was found) of water-bearing gravel and sand, interspersed with pockets of mud, and that to reach the rock with the foundations, except along a portion of the north quay, would be out of the question. A longitudinal and a cross section of the site of the docks, showing the strata as ascertained from the bores, were shown on the

cartoons.

For the portion of north wall in the boulder-clay, and where the rock was within a depth of about 40 feet under cope level, the usual section of wall has been adopted; but for the remainder of the walls and bridge-seat, where the stratum is of sand and gravel &c., charged with an enormous quantity of water, especially under low-water level, and the rock at a depth of from 50 feet to 100 feet below copelevel, the system of cylinder substructure, recommended by Mr. Bateman and the author of this paper in 1869, and successfully carried into effect in the construction of Plantation Quay wall and 60-ton crane-seat there, in 1870-75, was again fixed upon. A small portion of the west wall of the dock is founded on sheet and bearing piles where the boulder-clay suddenly dips, and a timber-wharf outside of the dock-entrance, where the quay may be of a less permanent nature.

The cartoons showed the general details of the whole of these walls, as well as of the bridge-seat.

The first contract, embracing the entrance and western portion of the docks' walls, was let in August 1872, the amount being fully £160,000.

The whole of the cylinders are of concrete, composed of 5 of gravel or broken stones and sharp sand to 1 of Portland cement of the strongest description, mixed together by steam-power with the necessary water. The cylinders for the quaywalls are about 27 feet 6 inches in height, made up of rings 2 feet 6 inches deep, the thickness being 1 foot 11 inches. These rings are formed within wooden moulds, on a platform, and, to facilitate lifting and break bond when built into the cylinder, they are divided into three pieces and four pieces alternately. The dividing of the rings is effected by iron plates placed across the mould in the positions required. The corbelling or bevelling of the bottom ring is done by placing contracting pieces in the mould on which to shape the ring. The seat for the iron washer on the top of the first, or "corbelled ring," and the holes for the bolts to secure the same to the iron shoe are also formed in the moulding of the rings. The concrete, as it is filled into the moulds, is well rammed with rammers weighing

25 lb., so as to secure homogeneity and a smooth surface. Twelve hours after filling the moulds the division-plates are withdrawn, and two days thereafter the moulds are removed from the sides of the rings; and in a period varying from nine days in dry hot weather to three weeks in rainy weather, the rings are ready for removal and building. The content of one ring complete is 10 cubic yards and the weight 18 tons; the heaviest portion weighs about 6 tons.

The shoes are of cast-iron, 2 feet deep, of the same external shape as the bottom of the cylinder, of 1-inch metal, with a bevelled inner shelf on which the corbelled ring of the cylinder rests, and to which it is secured with a malleable iron ring or washer, 5 inches by inch thick, held down by 14-inch bolts. The shoes of the ordinary triune cylinders weigh about 4 tons each, and, for convenience in handling, are made in six parts.

In the construction of the cylinder substructure, a trench is made in the line of the foundation (the bottom being about low-water level), of the necessary width, and slopes of about 1 horizontal to 1 perpendicular, over which, or alongside, is erected the necessary staging to carry the travelling cranes and digging apparatus. The shoes are placed on the bottom of the trench in proper line and position; the concrete rings are then built up in rings of three and four pieces alternately, pointed in cement, and the digging out of the sand or gravel &c. within the cylinder-wells is commenced. Special diggers or excavators have been designed for this purpose.

A load of from 300 to 400 tons of cast-iron weights is generally required during the sinking of each triune group of cylinders, to assist in sinking it to the proper depth, which is 48 feet 7 inches from the cope-level of the quay to the bottom of the shoe. The average rate of sinking is about 12 inches per hour in good working sand; however, as much as 3 feet per hour has been attained.

When each group of cylinders is sunk to the proper depth, the wells are filled to the top with Portland-cement concrete, lowered to its place carefully.

To effectually close up the apertures formed by the joining of each two groups of cylinders, a timber chock-pile, 25 feet long by 9 inches square, is driven behind, anglewise, so that a sharp corner may bear hard against each of the cylinders.

The foundation for the swing-bridge consists of twelve concrete cylinders, each 9 feet in external diameter, 29 feet in depth by 23 inches thick, formed in rings, and resting on cast-iron shoes, as described for the quay-wall foundations. After the cylinders were sunk, they and the interstices between them were cleaned out and filled to the top with concrete, chock-piles being driven where required. On the cylinder-foundation thus formed, a stepped ashlar pier, 16 feet square at the bottom and 10 feet square at the top, by 7 feet high, is erected, with a block of granite 7 feet square by 3 feet 6 inches deep, on which the centre lifting-press of the bridge rests. This pier is surrounded by concrete rubble, the whole forming a mass of masonry 36 feet 6 inches by 32 feet 6 inches by 10 feet 6 inches high.

The foundations for the hydraulic rams, capstans, and side walls of the bridge-pit are formed on single concrete cylinders placed apart and spanned between by brick arches. The cartoons showed the details of the foundations.

The first of the ground acquired for the docks was bought in 1845, at 68. 6d. per square yard, and the last in 1872, at 35s.

The total cost of the docks, when fully equipped, will approach £1,500,000.

Improved Safety-Apparatus for Mine-Hoists and Warchouse-Lifts.
By THOMAS DOBSON.

This apparatus, for checking the downward movement of the cage, or hoist-box, in case of the breaking of the suspending-rope or gear, consists of a mechanical arrangement of levers, which expand through the intervention of a spring acting upon the inner end of such levers through a sliding-sleeve, and so "strutting out," as it were, against the guides, or by gripping the guide-ropes, where ropes are employed instead of upright timbers.

On the Application of Spring Fenders to Pier-heads. By MORTIMER EVANS.

On a Safety-Lock for Facing-points. By MORTIMER Evans.

On the Experiments made at the Camp at Aldershot with a new form of Military Field-Railway, for rapid construction in war time. By J. B. FELL.

Field-railways are now recognized as being amongst the most important appliances in modern warfare; but hitherto it has been found impossible to have them constructed with such rapidity as to be available for the transport-service at the commencement of a war.

The Crimean war was far advanced before the Balaclava railway was finished. The Abyssinian war was over about the same time as the railway from Zoolla to the Koomaglee Pass was completed.

The railway made by the German army in the Franco-German war was not ready for working until within a few days of the fall of Metz, when it became useless.

The railway sent out to the Gold Coast was absolutely useless, and the difficulties and dangers of the expedition were much increased by want of the means of transport which the railway might have afforded for the first 30 miles on the road to Coomassie. Consequently the use of field-railways to a great extent depends upon the rapidity with which they can be constructed.

The cause of the partial failure of the military railways hitherto made is to be found in the impossibility of executing the works of which ordinary railways consist, such as cuttings, embankments, and masonry, with the rapidity necessary for laying down a field-railway at the commencement, or even in the early part of

a war.

Our Government have therefore had under consideration the practicability of adopting some other method of construction by which the difficulties hitherto experienced might be overcome. For this object the Royal Engineer Committee at Chatham have had a series of experiments carried out at the camp at Aldershot, of which Captain Luard, R.E., and the writer of this paper had charge. The experimental railway consisted of a succession of timber viaducts, which supplied the place of earthworks, culverts, and bridges, and which, when the materials had been prepared, could be erected with great rapidity. The conditions the Committee desired to have fulfilled in the trials were, that an engine, not exceeding six tons in weight, should take a train of thirty tons up an incline of 1 in 50, and travel at an average speed of 10 miles and maximum of 20 miles an hour. The waggons were required to carry a load of three tons of dead weight each, and from 300 to 500 cubic feet of bulky articles, such as tents, hay, and commissariat stores. A seven-ton siege-gun was to be carried on two waggons; and it was to be shown to be practicable to construct one mile of railway per day over such ground as was selected by the Committee at Aldershot, by the labour of 500 men.

The experimental railway was one mile in length, the gauge 18 inches; steepest gradient 1 in 50, the sharpest curve 3 chains radius, and one of the viaducts was 660 feet in length and 24 feet in height. The structure was of a simple form, and consisted of two beams, which were bolted to a kind of trestle-work supports, which were sunk to a depth of 12 inches and firmly fixed in the ground; the rails being laid on the beams, completed the railway, for the construction of which no other than military labour was required.

The experiments occupied at intervals a period of twelve months, and the Committee came to the conclusion that the result of the trials had proved that the above-named conditions had been in every respect complied with and exceeded. It had been shown that a single line of field-railway, constructed on the system employed at Aldershot, would be capable of carrying ammunition and commissariat stores sufficient for the supply of an army of 100,000 men; that a double line, and day and night service, would be capable of supplying an army of 300,000 men; that a single line of railway could be made, over ground similar to that at Aldershot, at the rate of 2 miles a day by 500 men; and that, if it should ever be required, it

would be possible to construct a field-railway at the speed at which an army of 100,000 men could march.

Besides the Royal Engineer Committee, a considerable number of civil and military engineers, both English and foreign, were present at the experiments.

In the course of the trials and subsequently improvements have been made in the form, materials, and details of the structure, by which the carrying powers and the efficiency of the railway have been considerably increased.

An ordinary transport ship accompanying an expedition would carry the materials and rolling-stock for 12 miles of field-railway, and the 'Great Eastern' steam-ship would carry from 70 to 80 miles.

The cost of the mile of railway at Aldershot, with sidings, stations, and rollingstock was £3500, and a similar railway of 2 feet 6 inches or 3 feet gauge, to be worked by engines of ten tons weight, and waggons carrying loads of six tons each, could be made for about £5000 per mile, the cost of erecting included.

Although a railway made on the system above described could not be expected to carry the same amount of traffic as one 4 feet 8 inches gauge, made in the ordinary way, it would be quite capable of performing the whole of the transport service for a large army in the field in a more efficient manner than it could be done by horses, at a much less cost to the country, and, in the opinion of military authorities, the value of such an improved method of transport in war-time could scarcely be overestimated. A difficulty, and perhaps the principal one remaining to be overcome, in practically carrying out this or any similar improved form of field-railway, is the necessity of incurring the expense in peace time of making provision for a future war; and no Administration would willingly assume the responsibility of such increased expenditure unless it were approved and required by the public opinion of the country. It is therefore desirable that publicity should be given to the experiments already carried out by the Government at Aldershot, and that the subject of the best method for the rapid construction of field-railways in war-time should be fully and freely discussed.

Railways on Three-foot Gauge in the United States.
By Capt. DOUGLAS GALTON, C.B., F.R.S.

In recent years a considerable development of these lines has taken place. The railway in the United States is the pioneer road; it must be made as cheaply as possible at first, and improved as population increases.

There are at present 7973 miles projected and 2700 completed. The Denver and Rio Grande is intended to be 1700 miles long, of which 210 miles are completed. The estimate of cost of a narrow-gauge line in a prairie country is given by the promotors at £1900 per mile for line and £758 per mile for rolling-stock. I ascertained that the cost of the Montrose railway (28 miles long) was £2300 per mile, with two locomotives, two passenger-cars, one baggage-car, and thirteen freight-cars. This is a purely agricultural line, running up into a country up a high elevation, and with small traffic. The Parker and Karns City railway cost £5500 a mile; but it is only 10 miles long at present, and has an equipment of four locomotives, five passenger-cars, forty-six freight-cars, and a viaduct 400 feet long and 74 feet high. This line is for opening out an oil district.

The curves on the lines are in some places 120 feet radius, and some gradients are as much as 1 in 40.

The rolling-stock is as follows:-Engines for passenger traffic have a rigid wheel-base of 6 feet 6 inches, with four driving-wheels (coupled) of from 3 feet to 3 feet 4 inches diameter; the weight on each driving-wheel from 2 tous 4 cwt. to 2 tons 8 cwt.; total weight of engine from 24,000 lb. to 32,500 lb.

Freight-engines have six wheels coupled, and the wheels are from 33 inches diameter in some patterns to 40 inches diameter in others, and the weight on each driving-wheel is from 1 to 2 tons; the total weight of these engines is 20,000 lb. to 38,000 lb.

In the cars, the wheels are 24 inches diameter; they weigh from 15,000 lb. to 17,000 lb., and carry thirty-six passengers; they weigh from 410 lb. to 470 lb.

per passenger. The 4 feet 8 inch gauge cars weigh from 28,000 lb. to 33,000 lb., and carry from fifty to seventy passengers, or from 550 lb. to 600 lb. per passenger. The 3-foot gauge cars are 7 feet wide, which allows double seats on one side and single seats on the other, with an aisle down the centre. Recently the cars have been increased to 8 feet in width, which allows of four seats abreast, or a total of forty-seven passengers.

The freight-cars have wheels of 20 inches diameter. The covered freight-car weighs 10,000 lb. as against 17,000 lb. or 18,000 lb. for similar cars on the 4 foot 8 inch gauge; and the narrow-gauge cars carry 8 tons as compared with 10 tons carried on the standard gauge. Thus a train of sixteen cars of the standard gauge would load twenty cars on the narrow gauge, and the total weight of the narrow-gauge train would be 260 tons against 296 tons for the standard gauge, i. e. a saving of 36 tons, equivalent to 22 tons of additional freight.

Thus on the narrow gauge the paying load bears a greater proportion to the dead weight than on the standard gauge.

But the heavy weight of cars on the standard gauge has been brought about by necessity of strength to resist shocks received in course of traffic.

The narrow gauge has been hitherto constructed so as to be as light as possible, and the scantlings have been made in proportion to gauge; but evidence is already given of a desire to increase the weight; and the weights carried on the cars show that it is probable increased strength, i. e. weight, will have to be resorted to.

The great width which is coming into use for the cars, e. g. 8 feet on a base of 3 feet, must be unstable; and I do not think that this mode of increasing the proportion of paying weight can stand. But if cars of 8 feet wide are run, but little economy can be claimed for the 3-foot gauge on the ground of diminished width of railway.

The longer tracks of the United-States railways enable all the plant to pass easily round curves, and the use of radial axles also contributes to that end; and there was at the Exhibition the Miltimow axle, of which a specimen which had run 12,000 miles was shown, in which the wheels move on the axle independently of the axle; this materially diminishes friction on curves. A train with these axles has been running on the 3-foot railway in the Centennial grounds. These appliances enable the standard gauge to be constructed with curves practically as sharp as those on the 3-foot gauge.

The weight of rails depends on weight of engine: a standard-gauge engine can be made as light as the 3-foot-gauge engine; but the light engine will not draw heavy weights up the steep inclines necessary for a line which follows the contours of the ground. In the United States the 3-foot gauge has the conveyance of cars which can be more easily moved at stations than the cumbrous cars of the standard gauge.

The break of gauge entails a cost for transhipment of from 10d. a ton where the traffic is regular to 18. 6d. to 28. a ton where it is intermittent. The line may be useful as a pioneer line; but when the traffic becomes large it will have to be converted to the standard gauge. A standard-gauge line would answer all purposes, if made with a light rolling-stock.

On an Improved Grain-sieve. By J. H. GREENHILL.

On Improvements in Railway Appliances. By R. R. HARPER.

Dock- and Quay-Walls, Foundations, &c. By T. S. HUNTER.

In this paper the author described the construction of dock- and quay-walls, foundations of bridges, subways or tunnels, sewers, and works of a similar nature, and also the means used to facilitate such works.

In carrying on operations where the sinking of foundations has to be effected in situations where water permeates the sand or soil so as to flood the works, a dam

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