6. ENGINEERING-CIVIL AND MECHANICAL.

THE subject which has generally attracted the most interest during the past quarter has been the trial of H.M.S. Waterwitch,' which has been fitted with a Ruthven's hydraulic propeller. The results as to speed proved, however, anything but satisfactory. With an indicated engine power of 750 horses, scarcely more than one-third of that power was ascertained to have acted effectively in propelling the vessel, and the speed attained was but nine knots an hour. The mode of propulsion is by the ejection of jets from the sides of the vessel, a short distance above water line, the reaction of which upon the water causes the ship to be propelled forward in a direction opposite to that in which the jets act.

The great question of guns versus armour-plates, is still undecided; for whilst, on the one hand, guns can now be made that will pierce any thickness of metal hitherto employed as armour for ships, it is still possible to increase that thickness to 15 or even 20 inches, if necessary, which would defy the largest guns yet manufactured. Two iron-clads are at present under construction for the British Navy, namely, the Hercules' and the Monarch,' and their armour-plates will vary from four to nine inches in thickness.

Recent experiments at Shoeburyness have sealed the fate of steel shot and shells, and resulted in the final approval of Major Palliser's projectiles for battering purposes; and chilled-iron projectiles will henceforth be exclusively employed by sea and land for penetrating iron-plated defences.

The Armstrong Gun would appear to have had its day, for land purposes at least, and the Royal Gun Factories at Woolwich are now principally employed in the manufacture of large numbers of the Fraser guns. The Ordnance Select Committee has recently recommended that we should revert to muzzle-loading guns for field use, and that the existing store of breech-loading Armstrongs should be converted, if possible, into muzzle-loaders on the Woolwich principle. With regard to small arms, the Sneider principle of converting our Enfields into breech-loaders, does not, apparently, quite satisfy our military authorities. The Secretary of State for War has invited proposals for breech-loaders to replace the present service rifles, offering four prizes for the best guns and cartridges, and a sum of 3007. is to be allowed to each accepted competitor for expenses,

Constant improvements are now taking place in the construction of locomotives. Attempts are being made to roll locomotive boilers in one single tube, which would have neither seam nor joint, and several patents have recently been taken out with that object. Should the attempt prove successful, we may count upon a consider

able direct gain in the strength of boilers, and, probably, upon the disappearance of" furrowing," which generally appears to be localized in the near neighbourhood of a seam of rivets. A few years ago the safe limit of steam pressure in a locomotive boiler was considered to be but 50 lbs., and now many engines on the lines about London are worked at 160 lbs. Great advantage would follow the use of a higher pressure, as it would enable the steam to be worked more expansively, and this may probably soon be accomplished, since a small steel boiler has recently been made for Mr. Salt, of Saltaire, which has not one rivet in it; all the joints are welded, and it has been proved to 300 lbs., and is intended to work at 250 lbs. There is a growing tendency greatly to increase the weight of locomotives, as there is a constant demand for engines of greater and greater tractive power, and Mr. Fairlie is building one of 72 tons weight for the Paris Exhibition. By his plan of double bogies of coupled wheels, each driven by a separate pair of cylinders, he not only distributes the weight of the engine upon eight or twelve points, as required, but he obtains great ease of working round very short curves, the governing wheel base being that only of each bogie. On the Northern Railway of France four-cylinder engines have been in use since 1863, and it has been proved, by experience, that the cost of maintenance of a four-cylinder locomotive is less than that of ordinary engines in proportion to the power developed.

Two very useful little machines have lately been designed by Mr. R. Angus, Locomotive Superintendent, North Staffordshire Railway, the one being for the purpose of planing the valve-faces, and the other for boring the cylinders, of locomotives whilst they remain fixed on the engine, thus saving a large amount of manual labour and time.

Delegates have, during the past quarter, arrived in London from Nova Scotia, New Brunswick, and Canada, for the purpose of arranging for the commencement of the Intercolonial Railway to complete the line of communication between Halifax and Quebec. By the shortest of the three routes that have been surveyed, the distance is 588 miles, of which 192 miles are already occupied by railways, leaving 396 miles to be constructed to complete the communication. The estimated cost of construction is 8,3007. per mile, or 3,286,8007. for the whole length, and it is understood that an Imperial guarantee of the interest upon 3,000,0007. has been conceded for the line.

A short line of railway has recently been opened in one of the most hilly outskirts of Paris, namely from Enghien to Montmorency. The length of this new line is less than two miles, and its peculiarity is that it consists almost entirely of curves of 300 metres radius, and inclines of 0.045, with the exception of a level bit of 150 metres at either end. The completion of the Chemin de Fer

de Ceinture, the circular line to connect all the Paris termini, and its continuation to the Champ de Mars, for the purposes of the Exhibition next year, is now in hand, and presents many features of interest. A curious and ingenious method of enlarging the postoffice carriages has been adopted by the Lyons Railway Company. Two vans are connected together by a strong junction of leather, arranged bellows-fashion, so that it expands and contracts with the movements of the buffers, and forms a safe means of communication between the two carriages.

A remarkable work is now in progress at the Place de l'Europe, in Paris. From that point, which is some 170 feet square, six roads, each 50 feet wide, diverge symmetrically, under which complication of thoroughfares the Chemin de Fer de l'Ouest passes through three openings, two of which are square, with spans of 98 feet 6 inches, and 82 feet respectively, and the remaining one skew, with a clear opening of 98 feet 6 inches, and a span of 102 feet.

In September last the opening took place of the section of the Madrid, Saragossa, and Alicante Railway, between Venta di Cardenas and Andujar, across the Sierra Morena, which was the only piece of line unfinished on the great route from Irun to Cadiz.

The Railways in Algeria conceded to the Lyons and the Mediterranean Railway Company are now actively in progress. The principal works being constructed at the present time are the prolongation of the Algiers and Blidah Railway to the valley of the Chetif, the Oran and Relizane Railway by Saint Denis-du-Sig, and the line from Phillippeville to Constantine.

From the last annual report on the Mont Cenis Tunnel, it appears that up to the end of last June the progress made at the Modane, or French side, amounted to 2,321 metres, of which 2,031 metres were completely finished. At Bardoneche, on the Italian side, the tunnelling was found to extend to 3,470 metres, of which 2,533 were finished. On the French side, the quartz rock had been met with at the exact spot anticipated by the geologists and engineers, and was not expected to extend beyond the 400 metres originally suggested. On the other hand, the work at the Italian end is reported to have made more rapid progress, in consequence of the softer character of the material to be passed through. The total length to be excavated is 12,220 metres, or about 7 miles.

In

In London, the works of the Metropolitan District Railway continue to make satisfactory progress, although they have been greatly impeded, owing to the numerous difficulties which beset the construction of an underground line through the metropolis. laying out such a line, not only have the levels of various streets passed under to be considered, but also those of the sewers, these latter often giving considerable trouble. At all points numbers of gas and water mains had to be dealt with, whilst at numerous

parts of the works special modes of construction must be adopted. The Metropolitan Extension Railway to Brompton and Notting Hill, passes in its course immediately beneath several fine and lofty houses at Pembridge Square. In order to avoid pulling these houses down, they have in the first place been underpinned; trenches were then dug, in which the side walls of the railway tunnel have been built, and wrought-iron girders are now being placed from wall to wall; the spaces between each girder will be arched over with brick in cement, and upon these the foundations of the houses will ultimately rest. The other principal works in progress in London are the Holborn Valley Improvement, the Thames Embankment, and the Metropolitan Main Drainage. With reference to the latter work, the quantity of sewage to be disposed of on the north and south sides of the Thames amounts to 10,000,000 and 4,000,000 cubic feet respectively, and the sewers have been proportioned for an increase up to 11,500,000 c. f., in addition to a rainfall of 28,500,000 c. f. per day on the north side, and up to 5,720,000 c. f., and a rainfall of 17,250,000 c. f. per day on the south side. Altogether there are now in London about 1,300 miles of sewers, and 82 miles of main intercepting sewers, and the pumping power amounts to 2,380-horse power nominal, whilst the execution of the main drainage works has involved the excavation of 3,500,000 cubic yards of earth, and the consumption of 880,000 cubic yards of concrete, and 318,000,000 of bricks.

An improved machine for tunnelling through soft ground has been invented by Mr. R. Morton, of London. It consists of a tube the size of the tunnel, formed of rings of cast iron, in front of which a large wrought-iron wedge-shaped shield is pushed by hydraulic pressure. This shield is made at the back of a similar section to the tube, over which it makes a movable but watertight joint; the pointed shield having been thrust forward a few feet, another ring of segments is added to the tube inside the shield, and the work goes on as before.

On the 11th October the inauguration of a graving dock at Suez took place. The dimensions of the dock are sufficient for it to contain ships of the largest tonnage, its length being 492 feet, its breadth 95 feet, and depth, 32 8 feet. The total cost of the work amounted to 360,0007.

Mr. Richardson's experiments in Woolwich Dockyard on the use of petroleum as fuel are likely to lead to very important results. Already we hear that one of the locomotives on the Scinde Railway is about to be fitted with apparatus on this gentleman's plan, and in the event of the experiment proving successful, it is intended to take advantage of the large quantities of petroleum which are procurable from Assam.

One of the four great tubes of the Waterloo, and Whitehall

Railway is now completed at Messrs. Samuda's yard, Poplar. It is 230 feet long, 12 feet 9 inches internal diameter, and is formed of -inch boiler plate, surrounded by four rings of brickwork; its weight as it lies is nearly 1,000 tons, Bulkheads are to be fitted at each end, when it will be floated to its destination above Hungerford Bridge. Here an inner ring of brickwork will be built inside it, and it will then be sunk upon its piers, and its ends secured in a junction chamber.

A pneumatic despatch tube is now being laid down in Paris, from the telegraph office near the Grand Hôtel, to that in the Place de la Bourse, and others will shortly connect those with the central telegraphic office on the other side of the river, the head-quarters of the post-office, and other stations. The system adopted in Paris is the reverse of ours. While we exhaust the air in advance, our neighbours' system is to compress it behind the despatch truck, at a pressure of one atmosphere and a half.

The surveys for the Russo-American telegraph have been completed from Anadyrsk to the Amoor, a distance of 6,000 versts, and the direction of the line has been determined. As soon as the sea of Ohkhotsk shall be free, vessels belonging to the Telegraph Company are expected to arrive at Guigiga from America with the necessary materials for commencing the works immediately. Already between Anadyrsk and Ohkhotsk the works have been commenced with the assistance of the inhabitants of the country, who are engaged in constructing houses and trimming trees to serve as telegraph posts.

An iron floating dock for Bermuda is now being constructed by Messrs. Campbell, Johnstone, & Co., of North Woolwich. It is to be capable of docking ships of the Bellerophon class when waterlogged; it is fitted with a caisson at each end, and has a double bottom and sides 20 feet apart. Its internal dimensions arelength, 330 feet; breadth, 84 feet; and depth, 52 feet.

The Norfolk Estuary Company have recently completed another embankment of a mile and a half in length, at Walferty, reclaiming another 300 acres of land in the “Wash.” This now makes a total of about 500 out of the 32,000 acres to be recovered from the sea.

The new Ladoga Canal has recently been opened for traffic. The first canal was commenced by Peter the Great, in order to develop the commerce of St Petersburg; it, however, proved inadequate to its purpose, owing to the defective system of locks. The new canal has no locks, and thus the project of Peter the Great, who intended that the first canal should be constructed without locks, is now realized.

The new screw pile pier at Brighton was opened on the 6th October last. The entire length of the structure is 1,115 feet; it is approached from the shore by an abutment 290 feet long and