Marvels of Scientific Invention Part 19

These chosen men then repair at intervals to the station to undergo a proper course of instruction. The instructor, often an ex-non-commissioned officer in the Royal Engineers, accustomed, therefore, to engineering matters, and also to systematic discipline, there puts them through a course of drill the object of which is to teach them to work together as a squad under the orders of a properly const.i.tuted chief. Thus when called upon in some emergency there will be no confusion, but each man will know what to do, and a few short words of command from the chief will serve better than the long explanations which would be necessary with an undisciplined body. It welds the individual men, as it were, into a smoothly working machine, thereby increasing the efficiency of the whole.

And arrangements are made whereby, should the leader fail, another man steps into his place of authority at once and without question.

Then, having thus brought them under a suitable discipline, the instructor takes his men into the experimental gallery. This may be described as a long, low, narrow shed, in which are timber props and beams, rails on the floor, heaps of coal, all things, in fact, which may tend to make it closely resemble the actual workings of a coal-mine after they have been shaken and shattered by the force of an explosion.

The great difficulty, in a real disaster, arises from what are known as "falls." The roof of the mine is normally supported by timbers, and these the explosion moves, so that in places many tons of the earth of which the roof of the mine consists will fall and block completely the "roads" or tunnels which communicate from the shaft to the places where the men are at work. These, of course, have to be removed or burrowed through before the men imprisoned in the distant workings can be reached. The rescue party do not, of course, wait to clear away the whole of this debris, only just enough to enable them to crawl through or over it, but even then it often represents the waste of precious hours, and the expenditure of great exertions, to get past a "fall." So at intervals "falls" are made in the gallery, in order that men may be practised in dealing with them.

[Ill.u.s.tration: _By permission of W. E. Garforth, Esq., Pontefract_

AN ARTIFICIAL COAL MINE

These two photographs show the clouds of flame and smoke issuing from the mouth of the "Artificial Coal Mine" during the experiments described in the text]

It may be interesting to give a brief statement of the training undergone by the men at the Mansfield Rescue Station. In that case, it should be stated, the gallery is made double, so that men can go one way and return the other back to their starting-point. Having donned their breathing apparatus, they enter the gallery, which, by the way, is filled with smoke and foul gas. Pa.s.sing along it, they encounter two falls, which they must get over or through; then they have to set twelve timber props as might be necessary to maintain the safety of a damaged road in the mine; all that they do three times over. Then they are required to bring up and lay 250 bricks, a thing which might also be necessary in an actual emergency, after which they have to fix up "brattice cloth" in a part of the gallery. One of the first duties, of course, for a rescue party is to restore the circulation of air in the mine, and brattice cloth is a rough kind of cloth which is put to guide the air currents. That done, they have to take a dummy representing a man of 14 stone, put it on a stretcher, and carry it round the gallery and over the falls. Finally, they restore the timber, bricks and cloth, and their turn of work is done. The total time required for this is two hours, and during the whole of that period they are, of course, breathing not the natural air, but the artificial atmosphere provided for them by the apparatus with which each man is provided. The chief point of this part of the training, as has been remarked already, is to accustom the men to the wearing of the apparatus and to doing work in it. By this means they gain confidence in it, and get to know that it will not fail them in the time of trial.

The course of instruction consists of ten drills such as has been described, after which the men are called up twice a year, just to refresh their memories.

One side of the gallery is glazed, so that the instructor can watch his men at work without of necessity being inside himself, and there are emergency doors as well, which can be opened to let a man out should the ordeal be too much for him. The necessary "fumes" are generated in a stove and driven into the gallery by a fan. The stations are beautifully fitted up, with baths for the men to wash after their somewhat dirty experience in the gallery, and everything is done for their convenience and welfare.

The advantage of this systematic training of a great number of men is that there are men at each colliery who can be called upon when needed.

The team of strangers, as has been remarked, partially failed at Courrieres, largely because they were strangers, but when every colliery has a team ready, composed of its own men, then clearly there is the greatest chance of success. The central station of the district is the training-ground where the men go from all the collieries to get the experience and instruction, and where a reserve store of appliances is kept. In many cases, of course, the collieries have their own appliances, so that work can be begun at once, without having to wait for that from the rescue station, but the latter forms a reserve in case of need, and, being kept under the care of an expert, it is naturally always in the best possible working order.

To give an idea of the cost of these stations, it may be stated that the one at Porth, in the Rhondda Valley, cost, including equipment, 7000, while the one at Mansfield cost 3000. This first cost and the expense of maintenance is borne by the collieries of the district in proportion to the quant.i.ty of coal which they raise.

And now we can turn to the apparatus itself, without which the organisation already described would be of little value.

There are several makes of these, but a description of the particular apparatus used at the two stations mentioned will serve as an ill.u.s.tration. The purpose, of course, is to give the wearer an atmosphere of his own, which he can carry about with him, and which will render him quite independent of the ordinary atmosphere and quite indifferent to the poisonous nature of the gases around him. To this end his mouth and nostrils must be cut off from the outer world altogether.

There are two ways of doing this. In the one there is used a helmet, or perhaps mask would be the better term. This fits right over the man's face, an air-tight joint being made between the helmet and his head by means of a rubber washer which can be inflated with air. The inflation is accomplished by squeezing a rubber ball on the right-hand side of the helmet. In the centre is a gla.s.s window through which he can see easily, and since this is apt to become clouded by the dampness of his breath there is a wiper inside, which can be turned by a k.n.o.b on the outside, so that by simply turning his k.n.o.b with his hand he can clean the window at any time that may be necessary. Two soft pads inside the helmet bear one on the man's forehead and the other on his chin, and these, working in conjunction with a strap which pa.s.ses right round the back of his head, keep the thing firmly in position. In addition there is combined with the helmet a leather skull-cap which, being continued down behind, gives good protection to the head and neck.

The other form of apparatus consists of a mouth-piece and nose-clip. The mouth-piece, as its name implies, fits in the man's mouth, being supported and kept in position by a strap pa.s.sing behind the back of his head. Combined with it is a little screw clip which closes his nostrils.

The man also wears a leather skull-cap, from which straps depend to bear the weight of the mouth-piece and its attached tubes, so that the weight does not fall upon his mouth.

Either of these arrangements, it is clear, cuts him off from communication with the outer air, but that is only half the problem, for he must be given a subst.i.tute or he will be suffocated.

This part of the appliance he carries, knapsack fas.h.i.+on, upon his back.

First there is a rectangular case, called the regenerator, with, below it, two small cylinders of compressed oxygen. A suitable arrangement of pipes connects these together, and to the helmet or mouth-piece as the case may be.

When the man exhales, as we all know, the air which he then discharges from his lungs is deficient in oxygen and instead contains carbonic acid gas. The latter must be got rid of and replaced by pure oxygen. The exhaled air is therefore led down a pipe to the regenerator, where it comes into contact with several trays of caustic soda, a chemical which has a great affinity for carbonic acid. The result is that the latter gas is extracted from the impure air, finding a more congenial home in the caustic soda. It is then necessary to restore the normal quant.i.ty of oxygen, and so, as the air pa.s.ses on, it meets, in a little apparatus known as an injector, a spray of pure oxygen from the cylinders. Thus, after being purified and re-oxygenated, the air pa.s.ses on through more pipes to the helmet or mouth-piece, to be breathed once more. The apparatus contains sufficient oxygen and caustic soda for this to go on for a s.p.a.ce of two hours.

But during times of extra exertion a man needs more air than at others, for which provision has to be made, and so on his chest the rescuer carries a flexible bag divided into two compartments. Through one of these the exhaled air pa.s.ses on its way to the regenerator, while through the other the oxygenated air flows on its way to the man's mouth. When he is breathing hard, then, during a moment of extra exertion, and when, therefore, he is turning out bad air faster than it can be purified, and drawing in pure air faster than it can be produced, this bag comes to his aid. From the store of oxygenated air in one side of it he draws the extra which he requires, while the other side stores up temporarily the excess of vitiated air, until the regenerator is able to overtake its work. Thus at all times, whether breathing ordinarily or heavily, the apparatus can respond to his demands.

The spray of oxygen as it escapes from the cylinders into the injector has the effect of driving the air along, so that the circulation through the tubes and the regenerator is automatic, and the foul air flows away from the man's mouth and the new air comes back to him quite without effort on his part. As time goes on, of course, and the stored oxygen becomes used up, the pressure in the cylinders falls, which fall, shown upon a little pressure-gauge, tells the man how much longer time he has before he must return for fresh supplies of oxygen and soda. Fresh cylinders of oxygen can be connected up very quickly in place of the empty ones, while a fresh regenerator can be put in, or new caustic soda supplied, in a very short time.

The superintendent of the Mansfield station has invented what is termed a "self-rescue" apparatus, to be used in conjunction with that which has been described above. It is simpler and lighter than the rescue apparatus, and will not keep a man supplied with air for more than an hour or an hour and a quarter. Moreover, it is not automatic, since the flow of oxygen has to be controlled by the man himself. Since, however, it consists only of a mouth-piece, a breathing-bag and a cylinder of oxygen, it is very portable, and may well be carried by a rescue party for the use of any men who may be discovered alive beyond the danger zone. It may well happen, indeed it often has happened, that a remote part of a mine, although cut off from the shaft by pa.s.sages full of "after-damp," as the foul gases caused by the explosion are termed, may itself contain fairly pure air in which men can live for a long time. If such men be reached, the difficulty is to get them through the pa.s.sages containing the bad air. Consequently a rescue party which carried one or two of these light forms of apparatus could equip such men with them and then they could pa.s.s out with safety.

Another use, the one, in fact, from which the appliance draws its name, is the facility with which, by its aid, a man could set right a chance defect in his ordinary rescue apparatus. Suppose, for example, that a fully equipped man found something wrong, whereby he was prevented from getting his proper supply of purified air. Then, if the party had one of the self-rescue sets with them, he could slip off his helmet or mouth-piece, quickly replacing it, for a time, with the self-rescue mouth-piece. This might enable him to reach safety, or even to put the other apparatus right and then don it once more. The whole thing can be packed up into a small tin case which can be slung over one shoulder, and with the oxygen cylinder slung over the other one the complete outfit can be carried quite easily by a man in addition to what he is wearing himself.

Still another form of breathing appliance may well be taken on these rescue expeditions, and that is the reviving apparatus, for use upon those who have apparently ceased to breathe. In this case a mask is put over the sufferer's mouth and nose, and then the turning of a lever into a certain position causes oxygen to escape from a cylinder in such a way as to cause a suction which empties the man's lungs of the bad gases which have laid him low. That done, another movement of the lever and a deep breath of oxygen flows into his lungs in their place. Thus by alternating the positions of the lever an artificial respiration is set up far more effective than can possibly be attained by the ordinary method of moving the man's arms and pressing his chest. Indeed there are cases, such as when his arms or ribs are injured, when the ordinary method is impossible, but it is hard to imagine an instance when this beneficent apparatus could not be used, and so long as there be any spark of life left in the poor fellow there seems to be every reason to expect a complete revival as the result of its use.

Of course there are many other places where poisonous gases are likely to be met with, such as gas-works, chemical-works, limeworks, and so on, where this apparatus may be kept with advantage, in case of accident.

Indeed all that has been described above has its use apart from colliery explosions, although they are the outstanding opportunities for its employment. Old workings, tunnels which have been empty for a time, sewers--all these have, on occasion, to be entered, not to mention houses full of smoke, or factories full of chemical fumes, all of which form cases in which the rescue apparatus would find useful employment.

CHAPTER XIX

HOW SCIENCE HELPS TO KEEP US WELL

One branch of science--medical science--concerns itself almost entirely with health, but it would be out of place to refer to such matters here, even if the present writer were capable of doing justice to the subject.

A new medicine or a new method of operating upon a suffering patient would be quite correctly described as a scientific marvel, but it is not of such that this chapter deals, but rather with those great works by which the engineer, often taught by the medical man, promotes the health of a whole community.

Most important of these, perhaps, is the provision of pure water. Some places are more fortunately situated than others in this respect, being near streams flowing down from mountains clear and unpolluted, which can be drunk after the minimum of purification. Others have to make use of the waters of a moderately clean river, as London does those of the Thames and Lea, in which cases the greatest care has to be exercised in the filtration of the liquid before it can be sent out through the mains for domestic consumption.

In this particular domain invention has been comparatively slow. There are novel pumps, it is true, for handling the water, such as the Humphrey Gas Pump, which the Metropolitan Water Board (London) have installed for filling their great reservoirs at Chingford. In these an explosion of gas is the motive force. Water flows by gravitation into a huge iron pipe closed at the top but open at the bottom. It is so arranged that a quant.i.ty of gas shall be entrapped in the upper end, which, being exploded by an electric spark, drives the ma.s.s of water out. Some of it, together with a quant.i.ty of fresh water, presently comes surging back, entrapping a fresh supply of gas and causing a new explosion; and so it goes on over and over again. The particular pumps at the waterworks referred to discharge about fourteen tons of water at each explosion, of which there are nine every minute.

The special effect of these machines, however, is not to improve the public health so much as to relieve the public pocket, for their chief feature is that they work more economically than any other kind of pump.

The filters, by which the water is purified, are simply layers of sand, much the same as have been in use for many years, although in some cases chemistry is brought in and the work of the filters aided by the action of precipitants. These are substances which combine in some way with the impurities in the water, and carry them to the bottom of the tank or reservoir, while the pure water remains to be drawn off from the top.

This is also the most usual method by which water is softened. Hardness in water is due to the presence of certain salts which are dissolved out of the ground as the water percolates through it, and which are absent from rain-water. To get rid of these the hard water has chemicals mixed with it in a tank, from which it flows slowly through another tank. The effect of the added chemicals is to convert the soluble salts in the water into insoluble particles, which then tend to fall down to the bottom of the containing vessel. The slow pa.s.sage through the second tank is intended to give the particles time to settle.

[Ill.u.s.tration: SECTIONAL VIEW OF HYDRAULIC BUFFER AND RUNNING-OUT PRESSES OF A 60-POUNDER GUN]

Finally, to make sure that these have been all got rid of, the water traverses a filter, and then it is for all practical purposes as soft as rain-water. Some people are frightened of this artificially softened water, on the ground that chemicals have been added to it, supposing, apparently, that when they use such water they are really employing a chemical solution. That is quite wrong, however, for the added chemicals, combining with the "hardness," form substances which are quite easily extracted from the water altogether. If we liken the hardness to a number of pickpockets in a crowd, and the added chemicals to a number of policemen who come in to arrest the said pickpockets, finally leaving the crowd free from both pickpockets and policemen, we get a simple ill.u.s.tration of what takes place.

But almost equally important as the provision of pure water is the effective dealing with the drainage of a large town. Much offensive matter flows under the streets of our towns and cities, and if it is not to become a nuisance it must be scientifically dealt with.

Years ago the drains of London simply emptied themselves into the Thames, until, in 1864, two large drains were constructed, one on each side of, and approximately parallel with, the river, to intercept the old drains and to carry their contents to points many miles down towards the sea. Even that, however, by no means abated the evil, for it simply transferred it to a new place. The river was as foul as ever.

William Morris, in _News from Nowhere_, pictures the catching of salmon in the Thames off Chelsea, while one of London's prominent citizens, referring to what was being done in the direction of purifying the river, jocosely promised the members of Parliament a little fly-fis.h.i.+ng at Westminster. Equally remote, it is to be feared, from actual accomplishment, these two prophecies do certainly indicate the tendency of events, for science has enabled the authorities to relieve the long-suffering river of much of the pollution which they used to thrust into it.

The first great step was the introduction, in 1887, of a treatment in principle very like that just described for softening water. The liquid from the drains is gathered into large reservoirs, where chemicals are added to it, causing the heavier matter to be precipitated in the form known as "sludge."

The liquid portion, or "effluent," as it is called, which is left is discharged into the river just as the tide is ebbing, so that it is carried right away, and, being comparatively inoffensive, it pollutes the river very little indeed. The sludge, on the other hand, is pumped into special steamers, which carry it down to a certain spot off the Thames Estuary, where they drop it into the sea. The currents at the particular spot chosen are such that none of it returns to the river.

For a similar purpose electrolysis has been employed. In this process the sewage is made to flow between two iron plates which are connected up to a source of electric current so that they form electrodes, while the sewage is the electrolyte. The current decomposes the liquid sewage, causing chlorine and oxygen to be deposited upon that plate which forms the anode. This deodorises and purifies the sewage, in addition to which iron salts are formed on the iron plates, the effect of which is to precipitate the solid particles. Thus the same result is achieved as when chemicals are used, the main difference being that instead of chemicals being added, they are produced by the pa.s.sage of the current.

But, from the scientific point of view, the most interesting process of all is that in which bacteria or microbes are brought into the service.

The fact is familiar to most people that there are certain minute organisms which cause terrible diseases. It is not so well known that there are still more of them whose action is extremely beneficent. The writer has seen these minute living things described in a popular book as "insects," but they really belong to a low order of plant life, and, as has been said in an earlier chapter, in spite of the lowliness of their status in the order of creation, they are able to accomplish certain chemical processes which baffle the cleverest men. They are particularly good, or some of them are at any rate, at forming compounds in which nitrogen forms a part. Further, they can be divided into two cla.s.ses, the aerobic and the anaerobic. The former work best in air, while the latter need an absence of air while they perform their functions. After which preliminary explanation we can proceed to describe how they are induced to carry on this valuable work for mankind.

The sewage flows first of all into a tank from which light and air are excluded as far as possible. There the anaerobic microbes flourish and multiply, and in the course of their life work they convert the sewage into an inoffensive liquid. After an appropriate interval the liquid pa.s.ses to filter-beds, where it trickles over and through beds of c.o.ke, the effect of which is to aerate it very thoroughly, whereby the aerobic microbes come into action, completing the good work, so that nothing is left except a clean, colourless and odourless liquid. Indeed it is more than that, for the microbes have turned the offensive matter into nitrogenous compounds which, as we have seen in a previous chapter, are the best fertilisers. Hence this effluent, if placed upon the soil, is of great value.

The advantage of this to towns which are not blessed, like London, with a broad river and the sea near at hand needs no explanation.

The bacteria necessary to carry on the process are always present in sewage, and after any particular plant has been in operation for a little while there results an acc.u.mulation of them, so that the process becomes more and more active as time goes on. Mechanical ingenuity has so arranged matters that a sewage disposal plant on this system can be made quite automatic, requiring little or no attention for months together, the raw sewage flowing in at one end, while the odourless, harmless effluent pours out at the other.