if possible be prepared for such an attack, should it be made in the future. Ample evidence of this was given by what was going on at Belfast and Glasgow at the commencement of 1896. One district asked for an advance, and thousands of men were locked out in the other district by the mandate of an employers' federation just previously formed. Later on in the year auother large centre threw in their lot with the said federation, with the result that whenever any trivial matter arose an instant threat was made of a general lock-out, which, if enforced, would affect numbers of families too numerous to conjecture. Some of the bolder spirits amongst the men treat this federation of employers quite lightly, but example shows that all other newlyformed trade unions are eager for a contest, and whilst we may expect this extensive employers' federation to stand together

D

for defensive purposes whilst trade is good, we must also expect them to be aggressive so soon as slackness shows itself.

"Beyond this, new local employers' associations are numerous, whilst evidence is not wanting of ardent advocates desirous of federating even these for offensive and defensive action in inland towns. Such being the case, it is very essential that every care should be exercised in dealing with trade matters, and whilst trade is good, only make such claims as can be defended when there is not such a briskness as at present exists. Above all, the funds should be carefully guarded, built up as much as possible in the meantime, and no factions dispute entered into that not only wastes capital, but weakens the fighting powers of the men, as these should only be brought into action when a real benefit is to be struggled for. Past results show the need of this. As years go on ordinary claims upon the society increase, whilst two years of bad trade, as a rule, swallows up the savings of

or

and finds extended employment for members. War vessels, ordnance work, and engines of destruction (which, we devoutly hope, will never need to be used), come in the same category, and the cycle trade is an important factor, that, by present appearances, may eventually be equalled by motor cars vehicles at no distant date. The tonnage of vessels launched in 1896 (1,326,822 tons) is the highest on record. 1897 bids fair to even exceed this, as without including war vessels, there are at this date 300 vessels of 784,711 tons now under construction. These causes have made a demand for members that has been in excess of the supply, end at the time of writing we have less than per cent. of unemployed members in receipt of donation in the United Kingdom, whilst offers of vacant situations are of daily occurrence. So long as this prosperity continues, our funds must increase, and it is to be hoped that, wherever possible, members will adopt a like course, and increase their little savings,

as even a limited banking account makes a man self-reliant, and the possessor of a spirit of independence, rather than act the part of a serf to a hard and callous taskmaster."

where machines are employed, is no doubt too wellknown to most of our readers to need much, if any explanation. The usual method adopted is to rough out the carvings, or to cut away all the heavier part of the cutting that has to be done in the machine, leaving subsequently to be finished off by hand. This means, of course, that all the artistic part of the work has to be done by a very expensive process, that of hand carving.

As a rule, undercut work cannot be attempted by ordinary carving machines, and this all has to be done

branch of shipbuilding, it is therefore with pleasure that we take the opportunity of describing one of the most remarkable processes for the reproduction of wood-carvings in wood pulp that have recently been brought forward. While visiting the offices of Mr. Leslie Robinson, of Westminster, in reference to some information about the well-known Normand water-tube boiler, we saw lying on his table, some specimens of wood-carving reproduced by this process, and at our request Mr. Robinson kindly permitted us to photograph one of them for the purpose of illustrating this article. Although it is but a small specimen of carving it is sufficient to show anyone who is conversant with this class of work, the great points of excellence possessed by this process.

The ordinary method of producing wood-carvings

by hand after the work leaves the machine, which naturally renders any carved work with heavy undercut work, a very costly matter, and one of the strong points of the process now under our consideration is that heavy relief work can be produced at the price of a third or a quarter the cost of a similar article in ordinary wood carving. The importance of this to a large shipbuilding or shipowning company, who has a distinctive mark, crest, or monogram that they wish to incorporate in the design for the decoration of their ships can easily be imagined. They can reproduce them in quantities at very much less cost than in wood, and at the same time procure a much more artistic pattern than could be done in ordinary wood-carving, except at a very large outlay.

On asking Mr. Robinson how this process was

carried out, he replied that he was not at liberty at this stage to divulge exactly how they were produced, but we understand that they are made from actual wood-carvings, of which a mould is taken, and the wood pulp is then pressed into the moulds. All the processes for dealing with wood pulp that have as yet been brought under our notice have always been remarkable for the blurred or rounded off appearance of the carving, a complete absence of undercut work, and clean cut or straight edges. The well-known Lincrusta-Walton and papier mache processes have been most effectively used for ship decoration, and this process, though not covering the same ground as the Lincrusta process, should be a valuable adjunct to them, as they excel in flat frieze or panel work, whereas the present process is "par excellence," suitable for heavy relief and undercut work.

slower though her propellers may be making almost as many revolutions.

The reason for this is that there is a backward current induced by the forward motion of the boat. In this current the boat floats and is carried with it, just as she would be if stemming or ascending the current of a river, or if moving against the tide in an estuary. In order to understand the decline in progress of a boat when in a narrow waterway, it is necessary to realize that this current of displacement is passing sternwards, and that as the boat floats in the current she must be subject to its influence and must be carried aft bodily at its velocity. Her progress through the water may remain as in open water or nearly so; but her progress over the ground will be no more than her open water progress minus the velocity of the induced backward current." The apparent slip is firstly. the open water slip, and secondly the velocity of the displacement current which is dependent upon the difference between the cross section of the boat and the cross section of the waterway.

On some shallow canals ordinary screws are used, and it is not uncommon to find that when the pitch and revolutions give say 10 miles an hour, the actual speed of the boat is only three, and with the displacement current added, a speed of not more than 4 or 43 miles an hour can be accounted for.

Part of the loss the author thinks should be attributed to the violent rush of water which shoots away from an ordinary screw;

Although the material is not wood in the ordinary acceptation of the word, yet it has every appearance of wood, and when combined with, for instance, walnut panelling, it is impossible to distinguish between the two. It works exactly like wood, but has the further advantage that it will not split, chip, or crack. The process is a French one, and the artis tic taste displayed does great credit to the inventor, in fact we have rarely, if ever seen a system with which more beautiful and artistic effect can be produced for a given outlay than the process under consideration.

А

PARTIALLY IMMERSED SCREW
PROPELLERS.

PAPER on partially immersed screw propellers for canal boats by Mr. Henry Barcroft, of Newry, was read at the annual general meeting of the Institute of Mechar.ical Engineers held in the theatre of the Institution of Civil Engineers.

The author dealt first with the question of screw propeller action, and claims that, as no part of the surface of his screws exceeds an angle of 45 deg. with the beam of the vessel, "a greater percentage of efficiency is obtained than with the ordinary screw in which a considerable area of blade near the boss has an inclination greater than the right angle." points out that these partially immersed propellers have no influence on the steering when placed 34 ins. out of centre. The lighter Agnes, when one of the propellers was taken off, kept a perfectly straight course, steaming only with the remaining

one.

He

He then goes on to the question of size of screw. In the screws he has applied to barges "the large diameter enables the large blade to be cut off as soon as the angle reaches 45 degs., while yet retaining blade surface enough for operating on a sufficient quantity of water to minimise the slip, which is so excessive in a small screw of high velocity driving a slow and heavy boat."

The author devotes the rest of his paper to the consideration of the question of waterway, and the effect that the restricted channel has on the propulsion of the boat. He points out that the propeller of a boat, when moving freely in open water, may have an ordinary percentage of slip, but as soon as she enters into a confined section of waterway her progress becomes

water should travel aft no faster than before, there would still be a loss due to the head of water in front of the boat. The sources of disappearance of power are therefore two: that absorbed in heaping up the water in front of the vessel, and the friction produced by the sternward current kept in motion by

this head.

The new partially immersed propellers are so large that the water acted upon refuses to move backwards and the power is exerted almost wholly in moving the boat forward. This, he thinks, is the explanation of the fact that no wash is observed on the bank when his propellers are at work.

The author refers, in concluding his paper, to the objections which were taken to the partial immersion of his screw propeller owing to the loss of efficiency due to air being drawn down. He doubted very much if this loss was due to that fact; he thought it was due to part of the propeller being out of the water and the blade ceasing at that moment to propeller.

act

as a

At the conclusion of the paper the President called upon Mr. Thornycroft to open the discussion. Mr. Thornycroft, however, said that he should prefer to defer his remarks until Mr. Barnaby had spoken.

Mr. Sydney Barnaby said that he was very much obliged to Mr. Thornycroft for allowing him to say what he had to say first, as he knew, if Mr. Thornycroft had spoken, there would be very little left for him to talk about. A good deal was said as to the comparative merits of large and small screws. Large and small were, however, only relative terms. Having regard to the resistance of the canal boat and the speed of propulsion, about 3 knots, he should not call a pair of 4 ft. 10 in. screws large even if they were fully immersed; but partially immersed, as they were, he should call them very small screws, and he was surprised they propelled as well as they did. He took exception to the statement that with large propellers the water refuses to move away backwards. All that can be said is that a larger amount of water is moved at a less speed.

As to the wash on the bank of the canal he should think the form of propeller used would have very little influence upon it. It must surely depend upon the form of the boat and the speed at which it is driven. If the speaker had a patent propeller he would never claim that it reduced the wash upon the bank of the canal, as he thought it could only do so by driving the boat slower than the screw it replaced. He would, however, like to design not only the screw but the barge as well if he wanted to reduce the wash on the bank; indeed, he would like to have had a finger in the cutting of the canal also. As to the effect of air being drawn down, he could speak with some authority, having a few years ago assisted Mr. Thornycroft in making a number of experiments with screws, some of which were for the purpose of determining this very point. It was found that the effect of air was very great indeed, and far more than could be accounted for by the reduction of ares due to the partial emergence of the screw. In these experiments the relation of the power used for driving the screw to the then-t dalivered by it was greatly changed by

the admission of air. The same effect, although to a less extent, was obtained without lifting the screw out of the water at all. It was only necessary to convey air to the propeller by means of a tube from the water surface. The thrust of the screw fell off at once. The submerged screw propels partly by thrusting water away, and partly by drawing it towards the forward face of the blade. To do the latter the pressure of the atmosphere must be called into play to assist the pressure due to head of water over the screw, otherwise the speed of the water flowing to the screw is small. If air be admitted to the screw blades the atmospheric pressure is balanced, and that due tofhead alone can operate. The screw blades act then like the floats of a paddle wheel and propel almost entirely by thrusting. A paddle wheel should have its propelling surface much larger than that of a screw to give the same thrust and the same efficiency, and therefore if partially immersed screws were used for any but very slow speeds they should be considered to be inclined paddle wheels and should have a proportionally larger surface. At a depth of 1 ft., which is the mean depth of immersion of the author's screws, water will flow at a velocity of

29 h

or about 6 knots. As this is above the velocity with which a portion of the blade below the water level moves through in the case of the Tyrone, very little if any air will get down. He was quite prepared to believe that the author suffered very little disadvantage on this score, and that his screws were much more efficient than would at first sight appear probable.

Mr. Thornycroft said there was one point he should like to speak on, and that was the displacement current. He thought that Froude's work was so well known that it was unnecessary to dwell upon it now. If he might be allowed to continue the water-line of Mr. Barnaby's diagram on the black board he would illustrate this point. The author had said the water was piled up in front, and that was so, but he quite spoilt Froude's diagram by leaving out the following current, which must not be ignored. He quite agreed with what Mr. Barnaby had said as to air getting down, but it must be remembered that at high speeds a different state of affairs prevailed: personally he had not had much experience of speeds of two miles an hour. He had seen a boat with an inclined paddle wheel which was something between a screw and a paddle. He himself had designed (some years ago) a screw tug-boat for a canal. Perbaps it was rather expensive, but, however, it was not accepted. He was informed afterwards that the directors had decided to put in donkey power as they cost practically nothing to keep, picking up all they wanted as the boats passed through the locks. He had designed some boats for the Bridgewater Canal where the water is only 3 ft. deep, and had put in a screw 5 ft. in diameter. This was reported upon by a local engineer, who said it would not work, but since then he had found it would.

Mr. Wicksteed said he had made a trip on the Pioneer, which is fitted with these adjustable propellers during the Belfast meeting last year, and he had a very good opportunity of studying the action of these propellers in the water. They entered it without a splash.

With regard to the employment of submerged and partially submerged propellers, Mr. Wicksteed thought that a larger cross-sectional area of blade would be obtained with a partially immersed propeller than with a totally submerged one, both being immersed to the same depth.

He thought that most probably the reason why the Admiralty coefficient of 62, given by Mr. Barnaby for the Tyrone, was not particularly high was probably due to the absorption of power by the gearing.

Mr. Scott made some remarks upon the New Mayne electric rudder motor, one of which was shown in the theatre. He said a high efficiency was obtained with this motor because it was cooled down by passing through the water. One advantage claimed for this motor is that the inclination of the propeller could be easily altered to prevent the settling down of the boat at the stern. They obtained their power from accumulators, but he hoped that the overhead wire and trolley might be introduced. They require 3 tons of accumulators for every 30 tons carried. The motor has a stationary armature, the field revolving.

Mr. Schonbeyder said that the inclined paddles mentioned by Mr. Thornycroft were the same in principle as the skew gear used in the Sellers planing machine.

Mr. Leslie S. Robinson said that he had had an opportunity of seeing the boats mentioned by the author at work, and he thought Mr. Thornycroft's and Mr. Barnaby's criticism was due to the fact that they had had more experience with boats of 30 knots speed than with boats having a speed of 2 knots. With regard to the falling off of the efficiency of the screw due to air being sucked down, M. Normand had also made some tests on the efficiency of screw propellers at varying depths of immersion. He suspended a torpedo boat over the quay at Havre, with her nose against the quay wall, and took readings of the thrust with a dynamometer. No sooner did the tip of the blade emerge from the water than the efficiency curve dropped very considerably.

He referred to the diagrams on the wall, which showed the enormous influence that the ratio of cross section of boat to canal had upon the tractive force. For a very small decrease in this ratio the effort of traction was tremendously increased. Nearly all the speakers had given the results of their experiences in open water; but it was absolutely impossible to argue from observation in open water as to what would happen in a canal. Mr. Barcroft, replying to the discussion, said he had not intended to put himself in opposition to generally accepted principles, as nearly all his own theoretical knowledge was taken from Mr. Barnaby's book. He was also aware of the experiments Mr. Thornycroft and Mr. Barnaby had carried out. What held good for high speeds did rot, however, apply to slow speeds. With regard to the drawing down of air, that might probably occur at high speeds, but he had not experienced it at those he was working at.

Mr. Leslie S. Robinson's paper on Canal Propulsion was adjourned till the next meeting. The proceedings were then concluded with the customary votes of thanks.

LAUNCH OF H.M.S. "NIOBE."

O ed, launched from

from sticking fast to the seat, but failure may happen from a wrong design, or the make or quality of materials used may be equally to blame. We all know, for instance, of arrangements which wiredraw the steam by preventing its free passage, spindle and wing valves being in this category for example. If fitted with renewable seats these latter may become loose, or not being bedded level, cause undue strain on the spindle.

To obviate these defects there is nothing like the old screw-down valve, if of good strong proportions, and well and accurately finished, and it is to follow out these ideas that the makers have introduced the present method as a combination of the advantages of that system with those of the ball and full way valves. The disc is spherical, and therefore offers no obstruction to the free passage of steam. It revolves on the spindle, is readily renewable, and screwing down as it does on the edge of the seat, a tight joint is made with the least amount of friction. The edge is of course, slightly chamfered off, and the seat made double the usual thickness to allow of its being reinstated after wear. It is apparent, therefore, that here we have a valve that meets most of the objections that may be raised to the usual types, and when we add that the machining and finishing takes place at one operation, a still further proof is afforded of everything connected with it coming true.

Besides the foregoing details, which will be appreciated by engineers generally, we are assured by the

SIR WILLIAM WHITE ON ADMIRALTY CRITICISMS. N Saturday, February 20th, the Naval Construction and yard at Barrow-in-Furness, H.M.S. Niobe, first-class cruiser. This vessel is one of eight, six of which are being built by contract, four on the Clyde, and two at Barrow and the other two at Pembroke Dockyard. The Niobe is,35 ft. in length, between perpendiculars, but the overhanging stern and the projecting ram make the length, over all, 463 ft. The breadth, over sheathing, is 69 ft., and her moulded depth to the upper deck 39 ft. 9 in. The mean load draught of the vessel is 25 ft. 3 in., at which draught the displacement is 11,000 tons. The hull of the vessel is constructed of Siemen'sMartin steel, the heavy external framing of the ends, stem, and stern post, and propeller brackets, and the rudder frame being, as is usual in sheathed vessels, phosphor bronze castings.

The rudder is of the balanced type, and the stem curved outwards under the water, so as to form a formidable ram. Up to a height of about 9 ft. above the water-line, the steel shell of the vessel is sheathed with teak planking, and coppered. Two long bilge keels, to prevent rolling, are also fitted amidships. the vessel's bottom is constructed on the cellular principle, the inner skin being carried from the protective deck at one side down, and up to the protective deck at the other side. The double bottom, or the space between the two skine, is minutely subdivided into water-tight compartments, which are partly used for the carrying of water, and which afford security against sinking should the outer skin be pierced. By water-tight bulkheads and water-tight flats the vessel is throughout closely subdivided. The protection consists of an armoured deck of steel plating 4 in. thick at the crown, which extends the whole length of the vessel. It is arched in section, rising from well under the water-line at the side of the vessel, to considerably above the water-line at the crown of the arch. Under the deck, which is raised for the purpose, in way of the engines are placed the propelling machinery, the steering engines and gear, the capstan engines, the air compressing machinery, and all the magazines, shell-rooms, and torpedo-rooms. The coal bunkers, which have capacity for over 2,000 tons of coal, are arranged along the sides of the boiler-rooms and along the sides of the vessel on the protective deck above the engines and boilers, thus affording most satisfactory coal protection to the machinery of the vessel. The armament of the vessel, as will be seen from the following, is of a most powerful description. There are 16 6-in. quick-firing guns; 12 12-pounder-quiok firing guns: 3 3-pounder quick firing guns; 2 12-pounder boat and field guns, and 8 45-in. Maxim machine guns.

The 6-inch guns are mounted as follows:- two on the forecastle head, two on the upper deck aft, the remaining. 12 being mounted on the broadside in armoured casemates,, constructed of Harveyed steel armour 6 in. thick. Of these 12 casemates eight are on the main deck level and four on the upper deck level.

The 12-pounder guns are mounted four an each broadside on the upper deck, two on the upper deck under the fourcastle, and two right aft on the main deck.

The 3-pounder guns are mounted on the boat platform deck.

The Niobe is supplied with three torpedo tubes, one of them firing right aft above the water-line, and two broadside under water-line; tubes placed under the protective deck in a special compartment forward.

The 6-inch guns, and 12-pounder guns will be supplied with ammunition through armoured tubes, extending from the protective deck to the deck on which the guns are worked.

An ammunition passage is arranged on each side of the ship, extending for the whole length of machinery space below the protective deck. The passage is completely protected by coal on top sides and bottom, so that the ammunition need never be exposed to fire in its course from the magazines to the guas. The conning tower, fi o n which the vessel is steered and directed when in action, is placed forward, and is built of Harveyed armour 12 in. thick. From it are led voice tubes, telegraphs, &c., down through a forged steel tube 7 in. thick, to the protective deck, and forward and aft underneath this deck to the engine-rcom, the guns, torpedo-rooms and steering positions.