The asphalt track and its equivalent will be the means of bringing much nearer to fulfilment the dream of having "a railway to every man's door". Many such tracks will be equipped with electric cables as well as guiding-rails, so that cars with electric motors will be available for running on them, and the power will be supplied from a publicly-maintained station. Some difficulty may at first be experienced in adjusting the rates and modes of payment for the facilities thus offered; but a convenient precedent is present to hand in the class of enactment under which tramway companies are at present protected from having their permanent ways used by vehicles owned by other persons. Practically the possession of a vehicle having a flanged wheel and a gauge exactly the same as that of the tram lines in the vicinity may be taken to indicate an intention to use the lines. Similarly a certain relation between the positions of guiding wheels and those of the connections with cables may be held to furnish evidence of liability to contribute towards the maintenance of motor-tracks.
Roads and railways will be much more closely inter-related in the future than they have been in the past. The competition of the automobile would in itself be practically sufficient to force the owners of railways into a more adaptive mood in regard to the true relations between the world's great highways. The way in which the course of evolution will work the problem out may be indicated thus:—First, the owners of automobiles will find it convenient in many instances to run by road to the nearest railway station which suits their purposes, leaving their machines in charge of the stationmaster and going on by train. In course of time the owners of "omnibus automobiles" will desire to secure the same advantage for their customers, and on this account the road cars will await the arrival and departure of every train just as horse vehicles do at present. The next step will be taken by the railway companies, or by the local authorities, when it becomes obvious that there is much more profit in motor traffic than there ever was in catering for the public by means of vehicles drawn by horses. Each important railway station will have its diverging lines of motor-traffic for the convenience of passengers, some of them owned and managed by the same authority as the railway line itself.
Rivalry will shortly enforce an improvement upon this system, because in the keen competition between railway lines those stations will attract the best parts of the trade at which the passengers are put to the smallest amount of inconvenience. The necessity for changing trains, with its attendant bustle of looking after luggage, perhaps during very inclement weather, always acts as a hindrance to the popularity of a line. When "motor-omnibuses" are running by road all the way into the city, setting people down almost at their doors and making wide circuits by road, the proprietors of these vehicles will make the most of their advantages in offering to travellers a cosy and comfortable retreat during the whole of their journey.
Road-motors, comfortably furnished, will therefore be mounted upon low railway trucks of special construction, designed to permit of their being run on and off the trucks from the level of the ground. The plan of mounting a road vehicle upon a truck suited to receive it has already been adopted for some purposes, notably for the removal of furniture and similar goods; and it is capable of immense extension. An express train will run through on the leading routes from which roads branch out in all directions, and as it approaches eachstation it will uncouple the truck and "motor-omnibus" intended for that destination. The latter will be shunted on to a loopline. The road-motor will be set free from its truck and will then proceed on its journey by road.
When a similar system has been fully adapted for the conveyance of goods by rail and road experiments will then be commenced, on a systematic basis, with the object of rendering possible the picking up of packages, and even of vehicles, without stopping the train. The most pressing problem which now awaits solution in the railway world is how to serve roadside stations by express trains. "Through" passengers demand a rapid service; while the roadside traffic goes largely to the line that offers the most frequent trains. In the violent strain and effort to combine these two desiderata the most successful means yet adopted have been those which rely upon the destruction of enormous quantities of costly engine-power by means of quick-acting brakes. The amount of power daily converted into the mischievous heat of friction by the brakes on some lines of railway would suffice to work the whole of the traffic several times over; but the sacrifice has been enforced by the public demand for a train that shall run fast and shall yet stop as frequently as possible.
Progress in this direction has reached its limit. A brake that shall conserve, instead of destroying, the power of the train's inertia on pulling up at a station is urgently required; but the efforts towards supplying the want have not, so far, proved very successful. Each carriage or truck must be fitted with an air-pump so arranged that, on the application of the brake by the engine-driver, it shall drive back a corresponding amount of air to that which has been liberated from the reservoir, and the energy thus stored must be rendered available for re-starting the train. Trials in this direction have been made through the application of strong springs which are caused to engage upon the wheels when the brake is applied, and thus are wound up, but which may then be reversed in position, so that for the starting of the vehicle the rebound of the spring offers material assistance. It is obvious, however, that the use of compressed air harmonises better with the railway system than any plan depending upon springs. The potential elasticity in an air-reservoir of portable dimensions is enormously greater than that of any metallic spring which could conveniently be carried.
In picking up and setting down mail-bags a system has been for some years in operationon certain railway lines indicating in a small way the possibilities of the future in the direction of obviating the need for stopping trains at stations. The bag is hung on a sliding rod outside of the platform, and on a corresponding part of the van is affixed a strong net, which comes in contact with the bag and catches it while the train goes past at full speed. Dropping a bag is, of course, a simpler matter.
The occasionally urgent demand for the sending of parcels in a similar manner has set many inventive brains to work on the problem of extending the possibilities of this system, and there seems no reason to doubt that before long it will be practicable to load some classes of small, and not readily broken, articles into trucks or vans while trains are in motion.
The root idea from which such an invention will spring may be borrowed from the sliding rail and tobogganing devices already introduced in pleasure grounds for the amusement of those who enjoy trying every novel excitement. A light and very small truck may be caused to run down an incline and to throw itself into one of the trucks comprising a goods train. The method of timing the descent, of course, will only be definitely ascertained after careful calculation and experiments designed to determine what length of time must elapse betweenthe liberation of the small descending truck and the passing of the vehicle into which its contents are to be projected.
Foot-bridges over railway lines at wayside stations will afford the first conveniences to serve as tentative appliances for the purpose indicated. From the overway of the bridge are built out two light frameworks carrying small tram-lines which are set at sharp declivities in the directions of the up and the down trains respectively, and which terminate at a point just high enough to clear the smoke-stack of the engine.
The small truck, into which the goods to be loaded are stowed with suitable packings to prevent undue concussion, is held at the top of its course by a catch, readily released by pressure on a lever from below. The guard's van is provided at its front end with a steel, upright rod carrying a cross-piece, which is easily elevated by the guard or his assistant in anticipation of passing any station where parcels are to be received by projection. At the rear of the van is an open receptacle communicating by a door or window with the van itself. At the instant when the steel cross-piece comes in contact with the lever of the catch, which holds the little truck in position on the elevated footbridge, the descent begins,and by the time that the receptacle behind the van has come directly under the end of the sloping track the truck has reached the latter point and is brought to a sudden standstill by buffers at the termination of the miniature "toboggan". The ends of the little truck being left open, its contents are discharged into the receptacle behind the van, from which the guard or assistant in charge removes them into the vehicle itself. For catching the parcels thrown out from the van a much simpler set of apparatus is sufficient.
On a larger scale, no doubt in course of time, a somewhat similar plan will be brought into operation for causing loaded trucks to run from elevated sidings and to join themselves on to trains in motion. One essential condition for the attainment of this object is that the rails of the siding should be set at such a steep declivity that, when the last van of the passing train has cleared the points and set the waiting truck in motion by liberating its catch, the rate of speed attained by the pursuing vehicle should be sufficiently high to enable it to catch the train by its own impetus.
It may be found more convenient on some lines to provide nearly level sidings and to impart the necessary momentum to the waiting truck, partly through the propelling agencyof compressed air. Any project for what will be described as "shooting a truck loaded with valuable goods after the retreating end of a train," in order to cause it to catch up with the moving vehicles, will no doubt give rise to alarm; and this feeling will be intensified when further proposals for projecting carriages full of passengers in a similar method come up for discussion. But these apprehensions will be met and answered in the light of the fact that in the earlier part of the nineteenth century critics of what was called "Stephenson's mad scheme" of making trains run twenty or even thirty miles an hour were gradually induced to calm their nerves sufficiently to try the new experience of a train journey!
The wire-rope tramway has hitherto been used principally in connection with mines situated in very hilly localities. Trestles are erected at intervals upon which a strong steel rope is stretched and this carries the buckets or trucks slung on pulley-blocks, contrived so as to pass the supports without interference. A system of this kind can be worked electrically, the wire-rope being employed also for the conveyance of the current. But an inherent defect in the principle lies in the fact that the wire-rope dips deeply when the weight passes over it, and thus the progress from one supportto another resolves itself into a series of sharp descents, followed by equally sharp ascents up a corresponding incline. The usual way of working the traffic is to haul the freight by means of a rope wound round a windlass driven by a stationary engine at the end. The constantly varying strain on the cable proves how large is the amount of power that must be wasted in jerking the buckets up one incline to let them jolt down another when the point of support has been passed.
Hitherto the wire-rope tramway has been usually adopted merely as presenting the lesser of two evils. If the nature of the hills to be traversed be so precipitous that ruinous cuttings and bridges would be needed for the construction of an ordinary railway or tramway line, the idea of conveyance by wire suggests itself as being, at least, a temporary mode of getting over the difficulty. But a great extension of the principle of overhead haulage may be expected as soon as the dipping of the load has been obviated, and the portion of the moving line upon which it is situated has been made rigid. A strong but light steel framework, placed in the line of the drawing-cable, and of sufficient length to reach across two of the intervals between thesupports, may be drawn over enlarged pulleys and remain quite rigid all the time.
The weight-carrying wire-rope is thus dispensed with, and the installation acquires a new character, becoming, in point of fact, a moving bridge which is drawn across its supports and fits into the grooves in the wheels surmounting the latter. The carriage or truck may be constructed on the plan adopted for the building of the longest type of modern bogie carriages for ordinary railways, the tensile strength of steel rods being largely utilised for imparting rigidity. We now find that instead of a railway we have the idea of what may be more appropriately called a "wheelway". The primitive application of the same principle is to be seen in the devices used in dockyards and workshops for moving heavy weights along the ground by skidding them on rollers. Practically the main precaution observed in carrying out this operation is the taking care that no two rollers are put so far apart that the centre of gravity of the object to be conveyed shall have passed over one before the end has come in contact with the next just ahead of it.
The "wheelway" itself will be economical in proportion as the length of the rigid carriage or truck which runs upon it is increased.The carrying of cheap freight will be the special province of the apparatus, and it will therefore be an object to secure the form of truck which will give, with the least expense, the greatest degree of rigidity over the longest stretch of span from one support to another. Some modification of the tubular principle will probably supply the most promising form for the purpose. The hope of this will be greatly enhanced through the recent advances in the art of tube-constructing by which wrought-iron and tough steel tubes can be made quite seamless and jointless, being practically forged at one operation in the required tubular shape.
For mining and other similar purposes, the long tubal "wheelway" trucks of this description can be drawn up an incline at the loading station so as to be partially "up-ended" in position for receiving the charges or loads of mineral or other freight. After this they can be despatched along the "wheelway" on the closing of the door at the loading end. In regard to the mode of application of the power in traction, the shorter-distance lines may serve their objects well enough by adopting the endless wire-rope system at present used on many mining properties.
But it is found in practice that for heavy freight this endless cable traction does notsuit over distances of more than about two miles. Mining men insist upon the caution that where this length of distance has to be exceeded in the haulage of ore from the mine over wire-rope tramways, there is need for two installations, the loaded trucks being passed along from one to the other by means of suitable appliances at the termini.
Electric traction must, in the near future, displace such a cumbrous system, and the plan upon which it will be applied will probably depend upon the use of a steel cable along which the motor-truck must haul itself in its progress. This cable will be kept stationary, but gripped by the wheels and other appliances of the electric motors with which the long trucks are provided. Besides this there must also be the conducting cables for the conveyance of the electric current.
For cheap means of transport in sparsely-developed country, as well as in regions of an exceptionally hilly contour, the "wheelway" has a great future before it. Ultimately the system can be worked out so as to present an almost exact converse of the railway. The rails are fixed on the lower part of the elongated truck, one on each side; while the wheels, placed at intervals upon suitable supports, constitute the permanent way. Theamount of constructional work required for each mile of track under this plan is a mere fraction of that which is needed for the permanent way and rolling stock of a railway, the almost entire absence of earth-works being, of course, a most important source of economy.
Probably the development of transport on the principles indicated by the evolution of the ropeway or wire-rope tramway will take place primarily in connection with mining properties, and for general transport purposes in country of a nature which renders it unsuitable for railway construction. This applies not merely to hilly regions, but particularly to those long stretches of sandy country which impede the transport of traffic in many rich mining regions, and in patches separating good country from the seaboard. In the "wheelway" for land of this character the wheels need not be elevated more than a very few feet above the ground, just enough to keep them clear of the drift sand which in some places is fatal to the carrying out of any ordinary railway project.
The conception of a truck or other vehicle that shall practically carry its own rail-road has been an attractive one to some inventive minds. In sandy regions, and in other places where a railway track is difficult to maintain,and where, at any rate, there would hardly be sufficient traffic to encourage expenditure in laying an iron road, a very great boon would be a kind of motor which would lay its own rails in front of its wheels and pick them up again as soon as they had passed.
A carriage of this kind was worked for some time on the Landes in France. The track was virtually a kind of endless band which ran round the four wheels, bearing a close resemblance to the ramp upon which the horse is made to tread in the "box" type of horse-gear. Several somewhat similar devices have been brought out, and a gradual approach seems to have been made towards a serviceable vehicle.
A large wheel offers less resistance to the traction of the weight upon it than a small one. The principal reason for this is that its outer periphery, being at any particular point comparatively straight, does not dip down into every hollow of the road, but strikes an average of the depressions and prominences which it meets. The pneumatic tyre accomplishes the same object, although in a different way, the weight being supported by an elastic surface which fits into the contour of the ground beneath it; and the downward pressure being balanced by the sum total of all the resistant forces offered by every part of the tyre whichtouches the ground, whether resting on hollows or on prominences.
Careful tests which have been made with pneumatic-tyred vehicles by means of various types of dynamometer have proved that, altogether apart from the question of comfort arising from absence of vibration, there is a very true and real saving of actual power in the driving of a vehicle on wheels fitted with inflated tubes, as compared with the quantity that is required to propel the same vehicle when resting on wheels having hard unyielding rims. So far as cycles and motor-cars are concerned, this is the best solution of the problem of averaging the inequalities of a road that has yet been presented; but when we come to consider the making of provision for goods traffic carried by traction engines along ordinary roadways, the difficulties which present themselves militating against the adoption of the pneumatic principle—at any rate so long as a cheap substitute for india-rubber is undiscovered—are practically insurmountable.
Large cart wheels of the ordinary type are much more difficult to construct than small ones, besides being more liable to get out of order. The advantages of a large over a small wheel in reducing the amount of resistance offered by rough roads have long been recognised,and the limit of height was soon attained. In looking for improvement in this direction, therefore, we must inquire what new types of wheel may be suggested, and whether an intermediate plan between the endless band, as already referred to, and the old-fashioned large wheel may not find a useful place.
Let the wheel consist of a very small truck-wheel running on the inside of a large, rigid steel hoop. The latter must be supported, to keep it from falling to either side, by means of a steel semi-circular framework rising from the sides of the vehicle and carrying small wheels to prevent friction. We now have a kind of rail which conforms to the condition already mentioned, namely, that of being capable of being laid down in front of the wheel of the truck or vehicle, and of being picked up again when the weight has passed over any particular part. The hoop, in fact, constitutes a rolling railway, and the larger it can with convenience be made, the nearer is the approach which it presents to a straight railway track as regards the absence of resistance to the passing of a loaded truck-wheel over it.
The method of applying the rolling hoop, more particularly as regards the question whether two or four shall be used for a vehicle,will depend upon the special work to be performed. Some vehicles, however, will have only two hoops, one on each side, but several small truck-wheels running on the inside of each. A vehicle of this pattern is not to be classed with a two-wheeled buggy, because it will maintain its equilibrium without being held in position by shafts or other similar means. So far as contact with the road is concerned it is two-wheeled; and yet, in its relation to the force of gravitation upon which its statical stability depends, it is a four or six-wheeler according to the number of the small truck-wheels with which it is fitted.
Traction engines carrying hoops twenty feet in height, or at any rate as high as may be found compatible with stability when referred to the available width on the road, will be capable of transporting goods at a cost much below that of horse traction. The limit of available height may be increased by the bringing of the two hoops closer to each other at the top than they are at the roadway, because the application of the principle does not demand that the hoops should stand absolutely erect.
Similar means will, no doubt, be tried for the achievement of a modified form of what has been dreamt of by cyclists under the name of a unicycle. This machine will resemble abicycle running on the inner rim of a hoop, and will probably attain to a higher speed for show purposes than the safety high-geared bicycle of the usual pattern. But it is in the development of goods traffic along ordinary roads that the hoop-rail principle will make its most noticeable progress. By its agency not only will the transport of goods along well-made roads become less costly and more expeditious, but localities in sparsely settled countries—such as those beyond the Missouri in America and the interior regions of South Africa, Australia and China—will become much more readily accessible.
A traction-engine and automobile which can run across broad, almost trackless plains at the rate of fifteen miles an hour will bring within quick reach of civilisation many localities in which at present, for lack of such communication, rough men are apt to grow into semi-savages, while those who retain the instincts of civilisation look upon their exile as a living death. It will do more to enlighten the dark places of the earth than any other mechanical agency of the twentieth century.
The "cargo slave" and the "ocean greyhound" are already differentiated by marked characteristics, and in the twentieth century the divergence between the two types of vessels will become much accentuated. The object aimed at by the owners of cargo boats will be to secure the greatest possible economy of working, combined with a moderately good rate of speed, such as may ensure shippers against having to stand out of their capital locked up in the cargo for too long a period. Hence cheap power will become increasingly a desideratum, and the possible applications of natural sources of energy will be keenly scrutinised with a view to turning any feasible plan to advantage. The sailing ship, and the economic and constructive lines upon which it is built and worked, will be carefully overhauled with a view to finding how its deficiencies may be supplemented and its good points turned to account. One result of this renewed attention will be to confirm, for some little time,the movement which showed itself during the past decade of the nineteenth century for an increase of sailing tonnage. Sooner or later, however, it will be recognised that sail power must be largely supplemented, even on the "sailer," if it is to hold its own against steam.
For mails and passengers, on the other hand, steam must more and more decidedly assert its supremacy. Yet the mail-packet of the twentieth century will be very different from packets which have "made the running" towards the close of the nineteenth. She will carry little or no cargo excepting specie, and goods of exceptionally high value in proportion to their weight and bulk. Nearly all her below-deck capacity, indeed, will be filled with machinery and fuel. She will be in other respects more like a floating hotel than the old ideal of a ship, her cellars, so to speak, being crammed with coal and her upper stories fitted luxuriously for sitting and bed rooms and brilliant with the electric light. But in size she will not necessarily be any larger than the nineteenth century type of mail steamer. Indeed the probability is that, on the average, the twentieth century mail-packets will be smaller, being built for speed rather than for magnificence or carrying capacity.
The turbine-engine will be the main factorin working the approaching revolution in mail steamer construction. The special reason for this will consist in the fact that only by its adoption can the conditions mentioned above be fulfilled. With the ordinary reciprocating type of marine steam machinery it would be impossible to place, in a steamer of moderate tonnage, engines of a size suitable to enable it to attain a very high rate of speed, because the strain and vibration of the gigantic steel arms, pulling and pushing the huge cranks to turn the shafting, would knock the hull to pieces in a very short time. For this very reason, in fact, the marine architect and engineer have hitherto urged, with considerable force of argument, that high speed and large tonnage must go concomitantly. Practically, only a big steamer, with the old type of marine-engine, could be a very fast one, and, for ocean traffic at any rate, a smaller vessel must be regarded as out of the running. Very large tonnage being thus made a prime necessity, it followed that the space provided must be utilised, and this need has tended to perpetuate the combination of mail and passenger traffic with cargo carrying.
The first step towards the revolution was taken many years ago when the screw propeller was substituted for the paddle-wheel. Thelatter means of propulsion caused shock and vibration not only owing to the thrusts of the piston-rod from the steam-engine itself, but also from the impact of the paddles upon the water one after the other. A great increase in the smoothness of running was attained when the screw was invented—a propeller which was entirely sunk in the water and therefore exercised its force, not in shocks, but in gentle constant pressure upon the fluid around it. Such as the windmill is for wind and the turbine water-wheel for water was the screw propeller, although adapted, not as a generator, but as an application of power. Having made the work and stress continuous, the next thing to be accomplished was to effect a similar reform in the engines supplying the power. This is accomplished in the turbine steam-engine by causing the steam to play in strong jets continuously and steadily upon vanes which form virtually a number of small windmills. Thus, while the screw outside of the hull is applying the force continuously, the steam in the inside is driving the shafting with equal evenness and regularity.
The steam turbine does not appear to have by any means reached finality in its form, such questions as the angle of impact which the jet should make with the surface of the vane, andthe size of the orifice through which the steam should be ejected, being still debatable points. But on one matter there is hardly any room for doubt, and that is that the best way to secure the benefit of the expansive power of steam is to permit it to escape from a pipe having a long series of orifices and to impinge upon a correspondingly numerous series of vanes, or, perhaps, upon a number of vanes arranged so that each one is long enough to receive the impact of many jets.
Hitherto the steam supply-pipe emitting the jet has been placed outside of the circle of the wheel; but the future form seems likely to be one in which the axis of the wheel is itself the pipe which contains the steam, but which permits it to escape outwards to the circumference of the wheel. The latter is, in this form of turbine, made in the shape of a paddle-wheel of very small circumference but considerable length, the paddles being set at such an inclination as to obtain the greatest possible rotative impulse from the outward-rushing steam. The pipe must be turned true at intervals to enable it to carry a number of diminutive wheels upon which these long vanes are mounted, and a very strong connection must be made between these wheels and the shaft of the screw. Inasmuch as a high speedof rotation is to be maintained, the pitch of the screw in the water is set so as to offer but slight opposition to the water at each turn. The immense speed attained is thus due, not to the actual power with which the water is struck by the screw at each revolution, but to the extraordinary rapidity with which the shaft rotates.
The twin screw, with which the best and safest of modern steam-ships are all fitted, will soon develop into what may be called "the twin stern". Each screw requires a separate set of engines and the main object of the duplication is to lessen the risk of the vessel being left helpless in case of accident to one or other. The advisability of placing each engine and shafting in a separate water-tight compartment has therefore been seen. At this point there presents itself for consideration the advisability of separating the two screws by as wide a distance as may be convenient and placing the rudder between the two. Practically, therefore, it will be found best to build out a steel framework from each side of the stern for holding the bearings of each screw in connection with the twin water-tight compartments holding the shafting; and thus will be evolved what will practically represent a twin, or double, stern.
In the case of the turbine steamer several of the forms of screw which were first proposed when that type of propeller was invented will again come up for examination, notably the Archimedean screw, wound round a fairly long piece of shafting. The larger the circular area of this screw is the less will be the risk of "smashing" the water, or of losing hold of it entirely in rough weather. With twin screws of the large Archimedean type the propelling apparatus of a turbine steamer will—if the screws are left open—be objected to on the ground of liability to foul or to get broken in crowded fairways. Hence will arise a demand for accommodation for each screw in a tube forming part of the lower hull itself and open at the side for the taking in of water, while the stern part is equally free. In this way there is evolved a kind of compromise between the two principles of marine propulsion, by a screw and by a jet of water thrown to sternward. The water-jet is already very successfully employed for the propulsion of steam lifeboats in which, owing to the danger of fouling the life-saving and other tackle, an open screw is objectionable.
The final extermination of the sailing ship is popularly expected as one of the first developments of the twentieth century in maritimetraffic. Steam, which for oversea trade made its entrance cautiously in the shape of a mere auxiliary to sail power, had taken up a much more self-assertive position long before the close of the nineteenth century, and has driven its former ally almost out of the field in large departments of the shipping industry. Yet a curious and interesting counter movement is now taking place on the Pacific Coast of America, as well as among the South Sea Islands and in several other places where coal is exceptionally dear. Trading schooners and barques used in these localities are often fitted with petroleum oil engines, which enable them to continue their voyages during calm or adverse weather. For the owners of the smaller grade of craft it was a material point in recommendation of this movement that, having no boiler or other parts liable to explode and wreck the vessel, an oil engine may be worked without the attendance of a certificated engineer. As soon as this legal question was settled a considerable impetus was given to the extension of the auxiliary principle for sailing ships. The shorter duration of the average voyage made by the sail-and-oil power vessels had the effect of enabling shippers to realise upon the goods carried more speedily than would have been possibleunder the old system of sail-power alone.
It is already found that in the matter of economy of working, including interest on cost of vessel and cargo, these oil-auxiliary ships can well hold their own against the ordinary steam cargo slave. Up to a certain point, the policy of relying upon steam entirely, unaided by any natural cheap source of power, has been successful; but the rate of speed which the best types of marine engines impart to this kind of vessel is strictly limited, owing to considerations of the enormous increase of fuel-consumption after passing the twelve or fourteen mile grade. For ocean greyhounds carrying mails and passengers the prime necessity of high speed has to a large extent obliterated any such separating line between waste and economy. It is, however, a mistake to imagine that the cargo steamer of the future will be in any sense a replica of the mail-boat of to-day. The opposition presented by the water to the passage of a vessel increases by leaps and bounds as soon as the rate now adopted by the cargo steamer is passed, and thus presents a natural barrier beyond which it will not be economically feasible to advance much further.
If then we recognise clearly that steam cargotransport across the ocean can only be done remuneratively at about one half the speed now attained by the very fastest mail-boats, we shall soon perceive also that the chances of the auxiliary principle, if wisely introduced, placing the "sailer" on a level with the cargo ship worked by steam alone, are by no means hopeless. A type of vessel which can be trusted to make some ten or twelve knots regularly, and which can also take advantage of the power of the wind whenever it is in its favour, must inevitably possess a material advantage over the steam cargo slave in economy of working, while making almost the same average passages as its rival.
Then, also, the sailless cargo slave, in the keen competition that must arise, will be fitted with such appliances as human ingenuity can in future devise, or has already tentatively suggested, for invoking the aid of natural powers in order to supplement the steam-engine and effect a saving in fuel. One of these will no doubt be the adoption of the heavy pendulum with universal joint movement in a special hold of the vessel so connected with an air-compression plant that its movements may continually work to fill a reservoir of air at a high pressure. The marine engines of the ordinary type will then be adaptedto work with compressed air, and the true steam-engine itself will be used for operating an air compressor on the system adopted in mines.
The pendulum apparatus, of course, is really a device for enabling a vessel to derive, from the power of the waves which raise her and roll her, an impetus in the desired direction of her course. Inventions of this description will at first be only very cautiously and partially adopted, because if there is one thing which the master mariner fears more than another it is any heavy moving weight in the hold, the motions of which during a storm might possibly become uncontrollable. When steam was first applied to the propulsion of ships the common argument against it was that any machine worked by steam and having sufficient power to propel a vessel would also develop so much vibration as to pull her to pieces—to say nothing of the risk of having her hull shattered at one fell blow by the explosion of the steam boiler. These undoubtedly are dangers which have to be provided against, and probably the occasional lack of care has been the cause of many an unreported loss, as well as of recorded mishaps from broken tail-shafts and screws, or from explosions far out at sea.
The air-compressing pendulum will no doubtbe constructed on such a principle that, whenever there is any danger of its weighty movements getting beyond control or doing any damage to the vessel, its force can be instantly removed at will, and the apparatus can be brought to a standstill by the application of friction brakes and other means. The weight may be made up of comparatively small pigs of iron, which, through the opening of a valve controlled from the deck by the stem of the pendulum, can be let fall out into the hold separately. The swinging framework would then be steadied by the friction brake gripping it gradually.
Auxiliary machinery of this class can only be made use of, as already indicated, to a certain strictly limited extent, owing to the tendency of any swinging weight in a vessel to aggravate the rolling during heavy weather. Some tentative schemes have been put forward for tapping a source of wave-power by providing a vessel with flippers, resting upon the surface of the water outside her hull, and actuating suitable internal machinery with the object of propulsion. A certain amount of encouragement has been given by the performances of small craft fitted in this way; but it is objected by sea-faring men that the behaviour of a large vessel, encumbered with outlying parts movingon the waves independently, would probably be very erratic during a storm and would endanger the safety of the ship itself. No kind of floating appendage, moving independently of the vessel, could exercise any actual force by the uprising of a wave in lifting it without being to some extent sunk in the water; and, accordingly, when the waves were running high there would be imminent risk that heavy volumes of water would get upon the apparatus and prevent the ship from righting itself. Many of the schemes that have been put forward, by patent and otherwise, for the automatic propulsion of ships have entirely failed to commend themselves by reason of their taking little or no account of the behaviour of a ship, fitted with the proposed inventions, during very rough and trying weather.
The swinging pendulum, with connected apparatus for compressing air or, perhaps, for generating the electric current, seems to be the most controllable and therefore the safest of the various types of apparatus which are applicable to the utilisation of wave-power for propulsion. In the construction of connecting machinery by which the movements of a pendulum hanging up from a universal joint may be transmitted to wheels or pistons operating compressors or dynamos, it is necessaryto transform all motions passing in any direction through the spherical or bowl-shaped figure traced out by the end of the pendulum in the course of its swinging. This may be effected, for instance, in the case of a pendulum working air-compressors, by mounting the latter on bearings like those of the gun-carriage in a field piece, and having two of them operating one at right angles to the other. The rods which carry the air-compressing pistons are then connected to the end of the pendulum by universal joints, and the parts which have been likened to a gun-carriage are fixed on pivots so as to be able to move horizontally. Air-tight joints in the pipes which lead to the compressed air reservoir are placed in the bearings of this mounting. We thus have the same kind of provision for taking advantage of a universal movement in space as is made in solid geometry by three co-ordinates at right angles to one another for measuring such movements.
Another plan is to have the pendulum swung in a strong steel collar and carrying at its end three or more air-compressing pumps set radially, with the piston-rods thrust outwards by a strong spring on each, but with the ends perfectly free from any attachment, yet fitted with a buffer or wheel. As the pendulummoves it throws one or more of these piston-rod ends into contact with the inner surface of the ring, driving it into the compressing pump. At the top of the pendulum there is a double or universal pipe-joint through which the air under pressure is driven to the reservoir, and by which the apparatus is also hung. This is the simplest, and in some respects the best, form.
A very simple type of the wave-power motor as applied to marine propulsion is based upon an idea taken from the mode of progression adopted by certain crustaceans, namely the possession of the means for drawing in and rapidly ejecting the water. Something of the kind will most probably be made available for assisting in the propulsion of sailing ships which are not furnished with machinery of any type suitable for the driving of a screw. A very much simplified form of the pendulous or rocking weight is applicable in this case. A considerable amount of cargo is stowed away in an inner hull, taking the shape of what is practically a gigantic cradle rocking upon semicircular lines of railway iron laid down in the form of ribs of the ship. To the sides of these large rocking receptacles are connected the rods carrying, at their other ends, the pistons of large force-pumps which draw thewater in at one stroke and force it out to sternwards, below the water line, at the other.
In this arrangement it is obvious that only the "roll" and not the "pitch" of the vessel can be utilised as the medium through which to obtain propulsive force. But it is probable that fully eighty per cent. of the movements of a vessel during a long voyage—as indicated, say, by the direction and sweep of its mast-heads—consists of the roll. Each ton of goods moved through a vertical distance of one foot in relation to the hull of the vessel, has in it the potentiality of developing, when fourteen or fifteen movements occur per minute, about one horse-power. A cradle containing 200 tons, as may therefore be imagined, can be made to afford very material assistance in helping forward a sailing ship during a calm. In such tantalising weather the "ground-swell" of the ocean usually carries past a becalmed vessel more waste energy than is ever utilised by its sails in the briskest and most propitious breeze.
For sailing ships especially, the rocking form of wave-motor as an aid to propulsion will be recommended on account of the fact that when the weather is "on the beam" both of its sources of power can be kept in full use. The sailing vessel must tack at any rate withthe object of giving its sail power a fair chance, and thus, when it has not a fair "wind that follows free," it must always seek to get the breeze on its beam, and therefore usually the swell must be taking it sideways. It would be only on rare occasions that a sailing vessel, if furnished with rocking gear for using the wave-power, would be set to go nearer to the teeth of the wind than she would under present conditions of using sail-power alone. The advantage of the wave-power, however, would be seen mainly during the calm and desultory weather which has virtually been the means of forcing sail-power to resign its supremacy to steam.
For checking the rocker in time of heavy weather special appliances are necessary, which, of course, must be easily operated from the deck. Wedge-shaped pieces with rails attached may be driven down by screws upon the sides of the vessel, thus having the effect of gradually narrowing the amplitude of the rocking motion until a condition of stability with reference to the hull has been attained.
In the building of steel ships, as well as in the construction of bridges and other erections demanding much metal-work, great economies will be introduced by the reduction of the extent to which riveting will be requiredwhen the full advantages of hydraulic pressure are realised. The plates used in the building of a ship will be "knocked-up" at one side and split at the other, with the object of making joints without the need for using rivets to anything like the extent at present required. In putting the plates thus treated together to form the hull of a vessel the swollen side of one plate is inserted between the split portions of another and the latter parts are then clamped down by heavy hydraulic pressure. This important principle is already successfully used in the making of rivetless pipes, and its application to ships and bridges will be only a matter of a comparatively short time. Through this reform, and the further use of steel ribs for imparting strength and thus admitting of the employment of thinner steel plates for the actual shell, the cost of shipbuilding will be very greatly reduced.
Hoisting and unloading machines will play a notable part in minimising the expenses of handling goods carried by sea. The grain-elevator system is only the beginning of a revolution in this department which will not end until the loading and unloading of ships have become almost entirely the work of machinery. The principle of the miner's tool known as the "sand-auger" may prove itselfvery useful in this connection. From a heap of tailings the miner can select a sample, by boring into it with a thin tube, inside of which revolves a shaft carrying at its end a flat steel rotary scoop. The auger, after working its way to the bottom of the heap, is raised, and, of course, it contains a fair sample of the sand at all depths from the top downwards. On a somewhat similar principle the unloading of ships laden with grain, ore, coal, and all other articles which can be handled in bulk and divided, will be carried out by machines which, by rotary action, will work their way down to the bottom of the hull and will then be elevated by powerful lifting cranes. For other classes of goods permanent packages and tramways will be provided in each ship, and trucks will be supplied at the wharf.
For coastal passages across shallow but rough water like the English Channel, the services of moving bridges will be called into requisition. One of these has been at work at St. Malo on the French coast opposite Jersey, and another was more recently constructed on the English coast near Brighton. For the longer and much more important service across the Channel submarine rails may be laid down as in the cases mentioned, but in addition it will be necessary to provide for static stability byfixing a flounder-shaped pontoon just below the greatest depth of wave disturbance, and just sufficient in buoyancy to take the great bulk of the weight of the structure off the rails. In this way passengers may be conveyed across straits like the Channel without the discomforts of sea-sickness.
The stoking difficulties on large ocean-going steamers have become so acute that they now suggest the conclusion that, notwithstanding repeated failures, a really effective mechanical stoker will be so imperatively called for as to enforce the adoption of any reasonably good device. The heat, grime, and general misery of the stoke-hole have become so deterrent that the difficulty of securing men to undertake the work grows greater year by year, and in recruiting the ranks of the stokers resort had to be had more and more to those unfortunate men whose principal motive for labour is the insatiable desire for a drinking bout. On the occasions of several shipwrecks in the latter part of the nineteenth century disquieting revelations took place showing how savagely bitter was the feeling of the stoke-hole towards the first saloon. As soon as the mechanical fuel-shifter has been adopted, and the boilers have been properly insulated in order to prevent the overheating of the stoke-hole, thestoker will be raised to the rank of a secondary engineer, and his work will cease to be looked upon as in any sense degrading.
On the cargo-slave steamer and sailer a similar social revolution will be brought about by the amelioration of the conditions under which the men live and work. Already some owners and masters have begun to mitigate, to a certain extent, the embargo which the choice of a sea-faring life has in times past been understood to place upon married men. Positions are found for women as stewardesses and in other capacities, and it is coming to be increasingly recognised that there is a large amount of women's work to be done on board a ship.
By and by, when it is found that the best and steadiest men can be secured by making some little concessions to their desire for a settled life and their objections to the crimp and the "girl at every port," and all the other squalid accessories so generally attached in the popular mind to the seaman's career, there will be a serious effort on the part of owners to remodel the community on board of a ship on the lines of a village. There will be the "Ship's Shop" and the "Ship's School," the "Ship's Church" and various other institutions and societies.
Thus in the twentieth century the sea willno longer be regarded, to the same extent as in the past, as the refuge for the ne'er-do-well of the land-living populace; and this, more than perhaps anything else, will help to render travelling by the great ocean highways safe and comfortable. It is a common complaint on the part of owners that by far the larger part of maritime disasters are directly traceable to misconduct or neglect of duty on the part of masters, officers or crew; but they have the remedy in their own hands.
Muscular power still carries out all the most laborious work of the farm and of the garden—work which, of course, consists, in the main, of turning the land over and breaking up the sods. In the operations of ploughing, harrowing, rolling, and so forth, the agency almost exclusively employed is the muscular power of the horse guided by man-power; with the accompaniment of a very large and exhausting expenditure of muscular effort on the part of the farmer or farm labourer. On the fruit and vegetable garden the great preponderance of the power usefully exercised must, under existing conditions, come direct from the muscles of men. Spade and plough represent the badges of the rural workers' servitude, and to rescue the country residents from this old-world bondage must be one of the chief objects to which invention will in the near future apply itself.
The miner has to a very large extent escaped from the thraldom of mere brute-work, orhardening muscular effort. He drills the holes in the face of the rock at which he is working by means of compressed air or power conveyed by the electric current; and then he performs the work of breaking it down by the agency of dynamite or some other high explosive. Much heavy bodily labour, no doubt, remains to be done by some classes of workers in mines; but the significance of the march of improvement is shown by the fact that a larger and larger proportion of those who work under the surface of the ground, or in ore-reduction works, consists of men who are gradually being enrolled among the ranks of the more highly skilled and intelligent workers, whose duty it is to understand and to superintend pieces of mechanism driven by mechanical power.
In farming and horticulture the field of labour is not so narrowly localised as it is in mining. Work representing an expenditure of hundreds of thousands of pounds may be carried out in mines whose area does not exceed two or three acres; and it is therefore highly remunerative to concentrate mechanical power upon such enterprises in the most up-to-date machinery. But the farmer ranges from side to side of his wide fields, covering hundreds, or even thousands, of acres withhis operations. He is better situated than the miner in respect of the economical and healthy application of horse-power, but far worse in regard to the immediate possibilities of steam-power and electrically-conducted energy. No one can feed draught stock more cheaply than he, and no one can secure able-bodied men to work from sunrise till evening at a lower wage.
Yet the course of industrial evolution, which has made so much progress in the mine and the factory, must very soon powerfully affect agriculture. Already, in farming districts contiguous to unlimited supplies of cheap power from waterfalls, schemes have been set on foot for the supply of power on co-operative principles to the farmers of fertile land in America, Germany, France, and Great Britain. One necessity which will most materially aid in spurring forward the movement for the distribution of power for rural work is the requirement of special means for lifting water for irrigation, more particularly in those places where good land lies very close to the area that is naturally irrigable, by some scheme already in operation but just a little too high. Here it is seen at once that power means fertility and consequent wealth, while the lack of it—if the climate be really dry, as in thePacific States of America—means loss and dearth. But the presence of a source of power which can easily be shifted about from place to place on the farm for the purpose of watering the ground must very soon suggest the applicability of the same mechanical energy to the digging or ploughing of the soil.
It is from this direction, rather than from the wide introduction of steam-ploughs and diggers, that the first great impetus to the employment of mechanical power on the farm may be looked for. The steam-plough, no doubt, has before it a future full of usefulness; and yet the slow progress that has been made by it during a quarter of a century suggests that, in its present form—that is to say while built on lines imitating the locomotive and the traction-engine—it cannot very successfully challenge the plough drawn by horse-power. More probable is it—as has already been indicated—that the analogy of the rock-drill in mining work will be followed. The farmer will use an implement much smaller and handier than a movable steam-engine, but supplied with power from a central station, either on his own land or in some place maintained by co-operative or public agency. Just as the miner pounds away at the rock by means of compressed air or electricity, brought to hishands through a pipe or a wire, so the farmer will work his land by spades or ploughs by the same kind of mechanical power. The advantages of electrical transmission of energy will greatly favour this kind of installation on the farm, as compared with any other method of distribution which is as yet in sight.
For the ploughing of a field by the electric plough a cable will be required capable of being stretched along one side of the area to be worked. On this will run loosely a link or wheel connected with another wire wound upon a drum carried on the plough and paid out as the latter proceeds across the field. For different grades of land, of course, different modes of working are advisable, the ordinary plough of a multifurrow pattern, with stump-jumping springs or weights, being used for land which is not too heavy or clayey; a disc plough or harrow being applicable to light, well-worked ground; and the mechanical spade or fork-digger—reciprocating in its motion very much like the rock-drill—having its special sphere of usefulness in wet and heavy land. In any case a wide, gripping wheel is required in front to carry the machine forward and to turn it on reaching the end of the furrow. The wire-wound drum is actuated by a spring which tends to keep it constantly wound up,and when the plough has turned and is heading again towards the cable at the side of the field, this drum automatically winds up the wire. So also when each pair of furrows has been completed, the supply-wire is automatically shifted along upon the fixed cable to a position suitable for the next pair.
Not only in the working, but also in the manuring, of the soil the electric current will play an important part in the revolution in agriculture. The fixing of the nitrogen from the atmosphere in order to form nitrates available as manure depends, from the physical point of view, upon the creation of a sufficient heat to set fire to it. The economic bearings of this fact upon the future of agriculture, especially in its relation to wheat-growing, seemed so important to Sir William Crookes that he made the subject the principal topic of his Presidential Address before the British Association in 1898.
The feasibility of the electrical mode of fixing atmospheric nitrogen for plant-food has been demonstrated by eminent electricians, the famous Hungarian inventor, Nikola Tesla, being among the foremost. The electric furnace is just as readily applicable for forcing the combination of an intractable element, such as nitrogen, with other materials suitablefor forming a manurial base, as it is for making calcium carbide by bringing about the union of two such unsociable constituents as lime and carbon.
Cheap power is, in this view, the great essential for economically enriching the soil, as well as for turning it over and preparing it for the reception of seed. Nor is the fact a matter of slight importance that this power is specially demanded for the production of an electric current for heating purposes, because the transmission of such a current over long distances to the places at which the manurial product is required will save the cost of much transport of heavy material.
The agricultural chemist and the microbiologist of the latter end of the nineteenth century have laid considerable stress upon the prospects of using the minute organisms which attach themselves to the roots of some plants—particularly those of the leguminaceæ—as the means of fixing the nitrogen of the atmosphere, and rendering it available for the plant-food of cereals which are not endowed with the faculty of encouraging those bacteria which fix nitrogen. High hopes have been based upon the prospects of inoculating the soil over wide areas of land with small quantities of sandy loam, taken from patchescultivated for leguminous plants which have been permitted to run to seed, thus multiplying the nitrogen-fixing bacteria enormously. The main idea has been to encourage the rapid production of these minute organisms in places where they may be specially useful, but in which they do not find a particularly congenial breeding ground.
The hope that any striking revolution may be brought about in the practice of agriculture by a device of this kind must be viewed in the light of the fact that, while the scientists of the nineteenth century have demonstrated, partially at least, the true reason for the beneficial effects of growing leguminous plants upon soil intended to be afterwards laid down in cereals, they were not by any means the first to observe the fact that such benefits accrued from the practice indicated. Several references in the writings of ancient Greek and Latin poets prove definitely that the good results of a rotation of crops, regulated by the introduction of leguminous plants at certain stages, were empirically understood. In that more primitive process of reasoning which proceeds upon the assumptionpost hoc, ergo propter hoc, the ancient agriculturist was a past-master, and the chance of gleaning something valuable from the field of common observationover which he has trod is not very great.
Modern improvements in agriculture will probably be, in the main, such as are based upon fundamental processes unknown to the ancients. By the word "processes" it is intended to indicate not those methods the scientific reasons for which were understood—for these in ancient times were very few—but simply those which from long experience were noticed to be beneficial. Good husbandry was in olden times clearly understood to include the practice of the rotation of crops, and the beneficial results to be expected from the introduction of those crops which are now discovered to act as hosts to the microbes which fix atmospheric nitrogen were not only observed, but insisted upon.
From a scientific point of view this concurrence of the results of ancient and of modern observation may only serve to render the bacteriology of the soil more interesting; but, from the standpoint of an estimate of the practical openings for agriculture improvements in the near future, it greatly dwarfs the prospect of any epoch-making change actually founded upon the principle of the rotation of crops. It is, indeed, conceivable that fresh light on the life habits of the minute organismsof the soil may lead to practical results quite new; but hardly any such light is yet within the inventor's field of vision.
This view of the limited prospects of practical microbiology for the fixing of nitrogen in plant-food was corroborated by Sir William Crookes in the Presidential Address already cited. He said that "practice has for a very long time been ahead of science in respect of this department of husbandry". For ages what is known as the four course rotation had been practised, the crops following one another in this order—turnips, barley, clover and wheat—a sequence which was popular more than two thousand years ago. His summing up of the position was to the effect that "our present knowledge leads to the conclusion that the much more frequent growth of clover on the same land, even with successful microbe-seeding and proper mineral supplies, would be attended with uncertainties and difficulties, because the land soon becomes what is called clover-sick, and turns barren".
In regard to any practical application of microbe-seeding, the farmers of the United Kingdom at the end of the nineteenth century had not, in the opinion of this eminent chemist, reached even the experimental stage, although on the Continent there had been some extensionof microbe cultivation. To this it may fairly be added that some of the attention attracted to the subject on the Continent has been due to the natural tendency of the German mind to discover fine differences between things which are not radically distinct. Under the title of "microbe-cultivation" the long-familiar practice of the rotation of crops may to some continental enthusiasts seem to be quite an innovation!
In the electrical manures-factory the operations will be simply an enlargement of laboratory experiments which have been familiar to the chemist for many years. Moist air, kept damp by steam, is traversed by strong electric sparks from an induction coil inside of a bottle or other liquor-tight receiver, and in a short time it is found that in the bottom of this receptacle a liquid has accumulated which, on being tested, proves to be nitric acid. There is also present a small quantity of ammonia from the atmosphere. Nitrate of ammonia thus formed would in itself be a manure; but, of course, on the large scale other nitrates will be formed by mixing the acid with cheap alkalies which are abundant in nature, soda from common salt, and lime from limestone.
In this process the excessive heat of the electric discharge really raises the nitrogenand oxygen of the atmosphere to a point of temperature at which chemical union is forced; or, in other words, the nitrogen is compelled to burn and to join in chemical combination with the oxygen with which formerly it was only in mechanical mixture. When nitrogen is burning, its flame is not in itself hot enough to ignite contiguous volumes of the same element;—otherwise indeed our atmosphere, after a discharge of lightning, would burn itself out!—but the continuance of an electric discharge forces into combination just a proportionate quantity of nitrogen. Practically, therefore, manure in the future will mean electricity, and therefore power; so that cheap sources of energy are of the greatest importance to the farmer.
With dynamos driven by steam-engines, the price of electrically-manufactured nitrate of soda would, according to the estimate of Sir William Crookes, be £26 per ton, but at Niagara, where water power is very cheap, not more than £5 per ton. Thus it will be seen that the cheapness of power due to the presence of the waterfall makes such a difference in the economic aspects of the problem of the electrical manufacture of manurial nitrates as to reduce the price to less than one-fifth! It must be remembered that at the closeof the nineteenth century the electric installation at Niagara is by very many persons looked upon as being in itself in the nature of an experiment, but at any rate there seems to be no room for doubt that the cost of natural power for electrical installations will very soon be materially reduced. Even at the price quoted, namely £5 per ton, the cost of nitrate of soda made with electrically combined atmospheric nitrogen compares very favourably with commercial nitrates as now imported for agriculture purposes. "Chili nitrate," in fact, is about fifty per cent. dearer.
When wave-power and other forms of the stored energy of the wind have been properly harnessed in the service of mankind, the region around Niagara will only be one of thousands of localities at which nitrogenous manures can be manufactured electrically at a price far below the present cost of natural deposits of nitrate of soda. From the power stations all around the coasts, as well as from those on waterfalls and windy heights among the mountains, electric cables will be employed to convey the current for fixing the nitrogen of the air at places where the manures are most wanted.
The rediscovery of the art of irrigation is one of the distinguishing features of modernindustrial progress in agriculture. Extensive ruins and other remains in Assyria, Egypt, India, China and Central America prove beyond question that irrigation played a vastly more important part in the industrial life of the ancients than it does in that of modern mankind. This is true in spite of the fact that power and dominion ultimately fell to the lot of those races which originally dwelt in colder and more hilly or thickly-wooded regions, where the instincts of hunting and of warfare were naturally developed, so that, by degrees, the peoples who understood irrigation fell under the sway of those who neither needed nor appreciated it. In the long interval vast forests have been cleared away and the warlike habits of the northern and mountainous races have been greatly modified, but manufacturing progress among them has enabled them to perpetuate the power originally secured by the bow and the spear. The irrigating races of mankind are now held in fear of the modern weapons which are the products of the iron and steel industries, just as they were thousands of years ago terrorised by the inroads of the wild hunting men from the North.
But the future of agriculture will very largely belong to a class of men who will combine in themselves the best attributes of the irrigationistand the man who knows how to use the iron weapon and the iron implement. As the manufacturing supremacy of the North becomes more and more assured by reason of the superior healthiness of a climate encouraging activity of muscle and brain, so the agricultural prospects of the warmer regions of the earth's surface will be improved by the comparative immunity of plant and of animal life from disease in a dry atmosphere. Sheep, cattle and horses thrive far better in a climate having but a scanty rainfall than in one having an abundance of wet; and so, also, does the wheat plant when the limited rains happen to be timed to suit its growth, and the best kinds of fruit trees when the same conditions prevail.
All this points to an immense recrudescence of irrigation in the near future. Already the Californians and other Americans of the Pacific Slope have demonstrated that irrigation is a practice fully as well suited to the requirements of a thoroughly up-to-date people as it has been for long ages to those of the "unchanging East". But here again the question of cheap power obtrudes itself. The Chinese, Hindoos and Egyptians have long ago passed the stage at which the limited areas which were irrigable by gravitation, without advanced methods ofengineering, have been occupied; and the lifting of water for the supplying of their paddy fields has been for thousands of years a laborious occupation for the poorest and most degraded of the rural population.
In a system of civilisation in which transport costs so little as it does in railway and steam-ship freights, the patches of territory which can be irrigated by water brought by gravitation from the hills or from the upper reaches of rivers are comparatively easy of access to a market. This fact retards the advent of the time when colossal installations for the throwing of water upon the land will be demanded. When that epoch arrives, as it assuredly will before the first half of the twentieth century has been nearly past, the pumping plants devoted to the purposes of irrigation will present as great a contrast to the lifting appliances of the East as does a fully loaded freight train or a mammoth steam cargo-slave to a coolie carrier.
At the same time there must inevitably be a great extension of the useful purposes to which small motors can be applied in irrigation. Year by year the importance of the sprinkler, not only for ornamental grounds such as lawns and flower-beds, but also for the vegetable patch and the fruit garden, becomes more apparent,and efforts are being made towards the enlargement of the arms of sprinkling contrivances to such an extent as to enable them to throw a fine shower of water over a very large area of ground. Sometimes a windmill is used for pumping river or well-water into high tanks from which it descends by gravitation into the sprinklers, the latter being operated by the power of the liquid as it descends. This mode of working is convenient in many cases; but a more important, because a more widely applicable, method in the future will be that in which the wind-motor not only lifts the water, but scatters it around in the same operation. Long helical-shaped screws, horizontally fixed between uprights or set on a swivel on a single high tower, can be used for loading the breeze with a finely divided shower of water and thus projecting the moisture to very long distances. A windmill of the ordinary pattern, as used for gardens, may be fitted with a long perforated pipe, supported by wire guys instead of a vane, a connection being made by a water-tight swivel-joint between this pipe and that which carries the liquid from the pump. In this way every stroke of the machine sends innumerable jets of water out upon the wind, to be carried far afield.