Science and War (Moulton)

by John Fletcher Moulton

For works with similar titles, see Science and War.

SCIENCE AND WAR

The Rede Lecture 1919

BY

The Rt. Hon. LORD MOULTON

K.C.B., F.R.S.

CAMBRIDGE
AT THE UNIVERSITY PRESS
1919

SCIENCE AND WAR

IT is a trite remark to say that the War from which we are just emerging is unexampled in History. It has involved by far the greater part of the civilized world. It has been waged not only on land and sea but in the air and under the water. All the fighting forces of the nations engaged in it have been put into the field until the man-power remaining has been hardly sufficient to do the work necessary to support the actual combatants. Women have been dragged into the work almost as universally as men. The demands for materials have in many cases far exceeded the resources of the nations involved, if not of the whole world itself. It has cost the lives of millions and condemned millions more to face the struggle of life, sick and maimed. It has left the nations burdened with debts reckoned in thousands of millions of pounds. So overwhelming has been the strain of it that, now that it is over, the very reaction shakes and threatens to disintegrate the foundations of civilization.

I am reminding you of these things not as bearing upon the choice that as a nation we made in entering into the conflict. Not all these disastrous consequences can make us regret that choice. Gigantic as must evidently be the cost it was not for us to count it. From the first it was clear that the future of the whole world was at stake, that the conflict was between World Dominion and Liberty and the memory of our past and the hopes of our future combined to make our path clear. But my object is not to dwell on these matters but to impress upon you that, the choice once made, the issue became one of such surpassing importance that it inevitably called into action all the powers, known or latent, of those engaged in the struggle.

If, with regard to such a War, we ask ourselves—What does it owe to Science? one is tempted to reply that in the first place it owes its very possibility to it. But for the stupendous advances that Science has made in times within the memory of many here present no catastrophe at once so wide-spreading and so deep-reaching could have happened. In scale and in intensity alike, this War represents the results of the totality of scientific progress—it is the realization of all that which the accumulated powers with which Science has endowed mankind can effect when used for destruction. We must be on our guard against treating the word Science in such a connection as though it included only the more recent advances that Science has made. Her Old and her New gifts have alike been put under contribution. The development of the human race has been the result of its increase in knowledge of the world around us, of the properties of the substances that it contains and the laws that govern them. Each such increase of knowledge has brought with it an increase of power. Man has learned more fully the resources of the world in which he lives and what assistance he can procure for himself therefrom when he seeks to effect something which is beyond his unaided powers. Thus, step by step, he has increased his capacities to an almost limitless extent. Gifted with only mediocre vision the telescope enables him to see the almost immeasurably distant and the microscope to see the almost immeasurably small. In spite of his little strength he can shatter in pieces the hardest rocks and lift the most stupendous weights. If we would learn to what he can attain in speed we must look to his skates, his cycles, his motors and his aeroplanes. The whole world is not too big for his powers of communicating instantaneously with his fellow man either by sign or speech. In short, although there is little ground for thinking that a man comes into the world endowed in any wise differently from his ancestors of many thousand years ago, the accumulated gifts of Science have opened out to the adult civilized mind of to-day the possibility of a life which covers a realm and which is endowed with powers wholly transcending those for which Nature framed him as an individual.

It is to men thus endowed that this War has come with all its overpowering motives and wild stimulus and to its service they have devoted all these acquired powers. To understand, therefore, what part Science has played in the War we must not only look at the new discoveries that have been made in direct connection with it but we must have regard also to the advances which had already begun to play their part in Peace, and which under the stress of War have been pressed into its service. Indeed we shall find that these have played at least an equal part among the great formative influences which made this War what it has been. That which has rendered the burden of the War so crushing has been the huge scale on which it has been waged and this has been the direct consequence of the extent to which the machinery of Peace has been utilized in it. Man mastered Transport, Aviation, Telegraphy and the like in order to add to the conveniences of Peace. It was a result though not a motive that he thereby revolutionized War.

There is one further consideration to be borne in mind if we would rightly appreciate the relation of Science to War as evidenced by the fateful years through which we have just passed. All these advances in knowledge and power of which I have spoken concern intellect only and not character, and we are learning to our cost that no development of intellect necessarily brings with it moral growth. No better proof could have been vouchsafed to us than our recent experiences. For at least half a century Germany had stood first among the great nations in its care for the education of its people. Science was everywhere cultivated and made accessible to the whole nation. Even allowing for the exaggeration of its claims due to its persistent self-glorification I do not doubt that the boast of the Germans that their country could shew a larger proportion of men of scientific attainments than any other was substantially justified and no doubt the influence of these men on the thought of their country was proportionately great. Yet we find Germany during a period of at least twenty years consciously and deliberately making preparations for a War to be waged upon its neighbours solely for the purpose of self-aggrandisement. When the War was at last commenced it was acclaimed and universally supported by the Nation. That it opened with a flagrant and undisguised breach of national faith affected the people not at all. At no time did they seek in any way to mitigate its horrors but made it their aim to increase them. Common soldiers co-operated with their officers and the higher commands in carrying it out with calculated and revolting brutality to the civilian populations of the invaded countries. Finally they introduced the use of asphyxiating gas and all the tortures of so-called Chemical Warfare. They thus realized the image which has been before my mind throughout this War when thinking of their ideal of the individual and of the Nation—that which they would have Science and Education make them. It is the monster which the Frankenstein of Mary Wolstencroft created—a human being with his powers magnified to those of a giant but destitute of moral sense. In setting the note of the horrors of this War the Germans have sought to imitate such a being—to deify Superior Force and to proclaim that it is all that is to be respected or to be striven for. That this National religion has brought them disaster is due to the fact that their supposed superiority was an illusion. Even with all the advantages of their long preparation and our unpreparedness we find that they had but little to teach us and that so soon as time had permitted us to organize our powers we were industrially and intellectually their equals if not their masters all along the line. But their conduct has taught us one lesson, viz. to put no faith in human perfectibility but to realize that in War one must be prepared to face the uncontrolled use of all the powers that Science, for good or evil, has given to mankind. There is no ground for thinking that from advance in knowledge there will come any increase in those restraining forces—call them honour, chivalry, humanity, respect for the laws of War or what you will—which operate to mitigate the horrors of War.

The history of the last half-century furnishes us with excellent material for appreciating the part which Science has played in this War. Forty-four years elapsed between the outbreak of the first Franco-German War and that of the one which is just concluding. The circumstances of the two were strikingly alike. In both we find Germany choosing its own moment for making a deliberate and long planned attack on France. In both cases it had accumulated a vast Army furnished with abundant provision of all munitions prescribed by the Military Science of the time. In theory if not in fact France was similarly equipped. The tactics of the attacking party were the same in both Wars and the immediate result in each case was a successful invasion of France. Fortunately the parallel between the two Wars goes no further. But the duration of each was sufficient to shew the features of a War waged with all the knowledge and appliances of the time, and thus the earlier war furnishes a datum line from which we can measure the changes that have been due to the scientific progress that has been made in the intermediate period.

The novel features thus introduced into War are so many and so varied that, either in form or in substance, well-nigh everything has been changed. In 1870 neither barbed wire existed nor its remedy the Tanks. The guns then used were mainly field guns although we find associated with them a few early attempts at rapid firing by means of mechanical guns such as the French Mitrailleuse. In the late war, on the contrary, we find on the one hand both armies using in the field large numbers of guns of heavy calibre firing at long ranges and on the other hand a new war of position with its special armament of machine guns, trench mortars, Stokes guns and hand grenades, constituting a system of almost continuous hand-to-hand fighting. The old mechanically-operated quick-firing guns have now been superseded by automatic machine guns which load and fire themselves by means of the spent energy of the preceding discharge and which being no longer dependent on human manipulation can fire at any desired rate up to say ten shots a second. Aeroplanes continually report by wireless telegraphy particulars of the movements of the enemy and the location of his guns and thus almost destroy the element of surprise that was once the main object of strategy. Where sight fails to locate his batteries, sound is made to do its work. Bombing by airships and aeroplanes forms a new branch of tactics as does also the offensive by gas attacks and the corresponding defensive by gas masks. Add to these the use of submarines and the power of instantaneous communication between the supreme command and each unit of a fleet wherever located by means of wireless telegraphy and we realize that it is no empty phrase to say that we have entered into a new era in War.

We shall find, as I have indicated, that the novel developments which are so characteristic of the recent war have been by no means exclusively due to scientific work that has been intentionally directed to warlike ends. Still they have owed much to such work and before I examine cases in which War has appropriated discoveries not made directly for its purposes I wish to shew you what Science can do when it takes in hand a purely military subject. With this object I will take the subject of Explosives, the basis of all modern warfare, and ask you to examine with me its history and present position.

The Science of Explosives is merely a study of the phenomena of Combustion. An explosive is nothing other than a combustible substance that can burn rapidly without needing to be in communication with the external air. This may sound a very gentle definition of so terrifying a thing as an explosive, the very name of which suggests the possession of enormous force under uncertain control. People are prepared to credit such a substance with secret stores of power wholly surpassing those that are possessed by other bodies. This however is far from being the case. It may surprise many of my hearers yet it is true that there is not, and it may safely be said that there never will be, an explosive which can give out nearly as much energy as an equal weight of coal or petroleum. Nitroglycerine stands almost first of our most violent explosives, and yet the power it can generate is less than one sixth of that given by the combustion of an equal weight of good coal. The difference in the effects in the two cases is due to the fact that the coal needs the oxygen of the air for its combustion. It can therefore burn only when the air has access to it. Hence combustion can take place only at its surface and the power developed is dissipated in streams of hot gases which must pass off as fast as they are formed, so as to allow fresh supplies of air to come forward. To put it into a closed chamber is to stop its burning. In an explosive this is not so. This is not because the combustible is different—that which burns in nitroglycerine is the same as that which burns in coal. But the oxygen necessary to burn it is to be found in the explosive itself, it has not to be got from without. The explosive can therefore burn with rapidity and within closed walls, and the hot gases thus generated, which are many hundred or even thousand times the volume of the explosive itself, give the sudden pressure which bursts the containing walls or, in a gun, drives out the projectile.

The history of Explosives is therefore the history of the means of laying up this oxygen close by the side of the combustible. It was first accomplished in the invention of Gunpowder. Here the combustible was a mixture of charcoal and sulphur, and the oxygen was contained in saltpetre which is the best known member of a class of bodies that contain large quantities of oxygen which is readily given off when they are heated to a high temperature in the presence of combustible matter. Gunpowder is a remarkable instance of successful invention. Whether it was Roger Bacon or some unknown Chinese forerunner who first devised it may be doubtful, but the ingredients were rightly chosen from the first, and the proportions have practically remained the same from early in the 14th century to the present day. It can boast of having satisfied all military requirements for five and a half centuries and is even now very far from being superseded.

Excellence in the Explosive was attained in the case of gunpowder by grinding the materials to fine powder and thoroughly incorporating them. Thus each particle of combustible had its necessary oxygen close at hand and when the combustion was started at some one point by a spark it rushed through the mass with a speed sufficient to cause the explosion. But some eighty years ago chemists found that it was possible to get a yet more perfect intermingling. They discovered substances in which the combustible and the oxygen are present in one and the same molecule. Like the lion and the lamb, of which the prophet speaks, they lie down together and it is not until the molecule is shattered by heat or shock or some other like agency that they rush together into combustion. As might be expected such a combustion is instantaneous, and the explosion it produces is very violent, far exceeding all that had previously been known. These bodies were the earliest forms of what are now known as High Explosives.

Such a discovery was sure to be seized upon for the use of War. But its employment was delayed from the very magnitude of its success. The explosions were too violent. These explosives could not be used in guns because they would burst the gun, nor in shells because even if they would stand the shock of firing, they would shatter the shell into too small fragments to be effective. So the use of these early high explosives in War except for blasting or like destructive purposes made little advance for many years until it was discovered that by dissolving them in some volatile solvent and subsequently driving it off, there was left a substance resembling gelatin which could be cut into pieces of any desired shape or size. It possessed all the power of the original explosive but its rate of burning was wholly different. You will understand the reason of this when I say that though it was a true explosive, burning with extreme rapidity, it was a poor conductor of heat. When the charge was fired all the pieces commenced to burn on the surface, and the combustion was so rapid that it spread itself through each piece of the material more quickly than the high temperature could arrive at the centre of that piece by conduction of heat. Hence it followed that the piece always burnt from the outside inwards and the explosion never commenced inside the piece, so that by changing the shape and size of the pieces into which the material was cut and thus making the extent of their surface large or small compared with their bulk, you could make a powder which would burn more or less quickly. For instance, a favourite method of increasing the rapidity of burning is by perforating the pieces so as to increase the surface without increasing the bulk. In this way there can be made out of the same substance powders suitable for small arms which require a very rapidly burning powder and others suitable for large guns which require a slowly burning powder. You must understand that I am using the words quick and slow in a comparative sense only. The actual time required is always small. In the biggest gun loaded with the coarsest powder the time of the burning of the charge would be something of the nature of one twenty-fifth of a second.

But that which caused the discovery of these gelatinized powders to revolutionize tactics both by land and sea was the fact that they were smokeless. In gunpowder there is much that takes no part in the combustion, and is expelled as fine dust. It is this which causes the smoke which always accompanies the use of gunpowder, and which not only fouls the gun but in olden times must have made aiming an impossibility after the first volley in continued firing. The great feat of Admiral de Saumarez, the local hero of Guernsey, was that he drove his frigate by night between two French Men-of-War that were lying parallel to one another, and fired simultaneously both his broadsides at them, and then sailed away leaving each to blow the other out of the water in the belief that it was firing at the adversary that had dared to attack it. The clouds of smoke prevented either discovering its mistake. But in the new powders nothing is left unconsumed. The whole is turned into invisible gas. Aiming therefore continues possible; indeed each shot is a sighting shot for the next. This makes it imperative that the position of guns should not be altered by firing, in order that they may correct their aim by previous results and they are therefore mounted in cradles with arrangements to take up the recoil, and return the gun to its original position after firing. Quickfiring and machine guns can be used With accuracy, and their use is now the fundamental consideration in much of our military tactics. It would indeed be hard to exaggerate the extent to which military science has been changed by this invention of smokeless powder.

But Science had not completed its service to War in respect of Explosives when it had thus endowed it with a perfect propellant. There remained the High Explosives with their tremendous pressures. Pressure in Explosives is measured by estimating the number of tons which each square inch of the containing wall has to bear when the explosion takes place. The pressures produced by the propellants of which I have been speaking may be taken to be of the order of 10 to 20 tons to the square inch. Recent measurements of those produced instantaneously by High Explosives point to a figure of 300 tons per square inch. But this inadequately expresses the contrast between them. It takes no notice of the rate at which the pressure rises. The rate at which that pressure comes on when a six inch gun is fired has been found to be about 10,000 tons per second so that it rises to the full pressure of 15 to 20 tons in something under the five hundredth part of a second. In a rifle the rate of rise is perhaps ten times as great but the period is proportionately shorter. But in a good high explosive the rate of rise per second is several millions of tons per square inch and the period is a fraction of a thousandth part of a second. Hence the shattering effect of these High Explosives.

Such violence of explosive force is just what is needed for shells, provided that the explosives are not too sensitive, or in other words that they can stand the shock of the discharge of the gun without exploding. But here a strange peculiarity shews itself. They have two ways of exploding. The one gives a comparatively mild explosion comparable say with that of gunpowder, the other a fierce detonation the violence of which is akin to that of guncotton. No one has penetrated the mystery of this. It undoubtedly depends on the initial disturbance which sets the explosive off. If that is of a sufficiently intense type and is rightly communicated to the mass of the explosive it produces detonation, and the shell is rent to pieces. If not we have only an explosion of ordinary violence which opens out the shell but does little more. It needed much research to give us practical control of high explosives in this respect. In the Boer War we used Lyddite in our shells—a high explosive of the finest quality—but we did not then know how to detonate it with certainty and in only one type of shell was it of substantial value. By the commencement of the late War we had however learnt how to detonate with fair but not absolute certainty the High Explosives then used in the service. But soon afterwards the prospect that our supply of toluol might fail to equal the enormous demands of our shells necessitated a change of high explosive and the one that was taken required special study before detonation could be ensured. It was achieved through the unremitting labour of those scientific workers who, little known to the public, have had to face and solve the innumerable problems that have presented themselves in the preparation and use of explosives during the War and to whom personally I feel deeply grateful. Through their labours we ultimately arrived at a degree of excellence which reduced the proportion of the shells which failed to detonate from all causes to so small a figure that it was, I believe, little more than one fifth of that of our adversaries.

It would take an artillerist to explain to you all the changes in tactics brought about by the scientific work that has given us these reliable explosives. It has endowed us with heavy guns of great accuracy having ranges of twenty to thirty miles and with the even more important Howitzers which have been so effective at shorter ranges. We have for instance had Howitzers which at ranges such as eight to fifteen miles could be relied on to fire shot after shot with a variation of a few yards. Consider what perfection of propellant, projectile and gun is required to enable a gun to repeat itself to that degree of accuracy. All this has been attained by scientific research into the causes of variation in the behaviour of the propellant and the gun and the determination of the right practice to be followed in their manufacture, and the history of our advance in artillery is a fascinating tale of difficulties met and overcome. But I must not linger on this subject and will content myself with a reference to the most striking example of the power placed in the hand of man by this complete control over propellants.

In the early part of last year, the world was thrown into amazement by the report that Paris was being bombarded by the Germans who could not be firing from a point less than 70 miles from it. It was at first incredulous. Then, as usual, it credited the Germans with having invented some new propellant of marvellous efficiency. But our artillerists knew better. They realized that thanks to the control of pressures and rates of burning in our present smokeless powders, such a range could be obtained in a gun of determinable dimensions if it were worth our while to do it. Indeed the whole details of the gun and the powder necessary to accomplish the feat were at once worked out, and such a gun would have been manufactured by us if it had possessed sufficient military value to warrant the work and expense. But it did not. The glory of firing at a city of say 100 square miles in extent, so that missing the target was impossible, merely for the sake of killing or frightening civilians had no attractions for us. The occurrence however possesses great interest for us because it shews the pitch to which Science has brought artillery by its work upon explosives. In its flight the projectile from Big Bertha must have reached a height four times as great as Mount Everest, the highest mountain in the world. It owed its long range to the fact that during two thirds of its flight it was passing through regions where the air was so rarefied that its resistance was negligible. And finally the distance passed over by the projectile was so great that if the Germans had taken the trouble to aim at any particular building they must have allowed nearly half a mile for the fact that during the flight the rotation of the earth would to that extent carry the target further towards the east than it would carry the gun.

So much for the help of Science in the realm of explosives. But I have said that the special formative factors of the late war were not the result of purely military science but of the advances made in peaceful pursuits, and to illustrate this I will take the case of the Internal Combustion Engine.

This is an application of our old friend "explosive combustion" to a very homely and peaceable purpose. The intimate mixture of combustible and oxygen is obtained by rapidly drawing into the cylinder a charge of petroleum vapour and the air requisite for its combustion with a rapidity that ensures their being churned up together and intimately mixed. The mixture is then lighted and the explosion that ensues drives the piston forward and makes the stroke. Such an engine therefore needs no supply from outside except the petrol that it burns. Boilers with their fires and their water supply (or its equivalent—their condenser system) disappear and this change is accompanied by a gain and not a loss of efficiency. This type of motor was in far too undeveloped a state to figure in the War of 1870 but it has been made the subject of years of highly scientific work in the hands of Sir Dugald Clerk and others until it has attained a degree of perfection which has enabled it to play a role of unparalleled importance in the late War. To it we owe the aeroplane, the tank, the submarine, the motor cycle and the possibility of a road motor service which has shewn itself capable of rivalling even railway transport.

Consider for a moment the requirements of the aeroplane. It is supported by inclined planes which must be driven through the air at such a velocity that the upward pressure on those planes is sufficient to lift the weight of the machine together with the engine, the petrol it requires, the passengers and any extra load such as bombs which it needs for its special work. All the power necessary for driving the planes against the air with sufficient speed for this purpose must be derived from the engines. The essential therefore of the engine of an aeroplane is extreme lightness together with economy of fuel as compared with the power produced. The improvements effected in the petrol engine during the war have brought the weight of the engine down to about two pounds per horse-power and the weight of the fuel required to about half a pound per horse-power hour. Even with these reduced weights the burden that has to be supported by an aeroplane starting on a long flight or on a bombing expedition is most formidable though it may be completely satisfactory for the aeroplanes which have to discharge their ordinary functions at the front. The weight of a fully equipped aeroplane varies from half a ton to several tons and its speed may go up to 100 miles or even 120 miles per hour. No one could suggest that any form of motor would be capable of discharging such duties other than the internal combustion engine.

In the same sense that the internal combustion engine made the aeroplane a practical proposition it must be said to have given us the Tanks. The essence of their success was their shape, the efficiency due to their compactness, and the perfect drive which they got from the endless tracks which ran round their periphery on each side. Many would protest against their invention being regarded as due to the scientist and would claim that they are wholly the product of the judgment and experience of the practical man. There may be much to say in favour of this view of the invention of the Tanks but it is clear that the very efficiency that secured their success could only have been obtained by making use of the internal combustion engine to drive them.

Without undervaluing the part played by the internal combustion engine in giving us the aeroplane and the tanks I must confess to a feeling that its greatest triumph has been in motor transport. It brought most of our heavy guns up to the front and fed them with their ammunition and indeed by its flexibility and adaptability to the varying needs and opportunities of the moment it was our main agent throughout the war in supplying our armies with necessaries. In one respect the Germans out-distanced the Allies throughout—viz. in the attention they paid to strategical railways which brought up to the front the vast supplies of ammunition and food needful by reason of the number of the troops employed and the unlimited use of heavy and field artillery in the warfare that constantly went on along the line of the trenches. In this part of their organization the Allies were inferior to the enemy and motor transport had to make up for their deficiencies. On one critical occasion it saved the war. We all remember how in 1916 the Germans concentrated their efforts upon Verdun. It may well be that one main reason for this was the inequality of the mechanism of supply of the combatants in that district. The Germans had ten strategic railways on their side. The French had but one second class railway and road communication. Yet their heroic defence was successful. The story was admirably told in an article in the Revue des deux Mondes in December last. Along the main road leading to Verdun the French organized a motor transport system which was a marvel. Two continuous lines of motor lorries moving in opposite directions operated day and night. Men stood all along the road with prepared rubble ready to mend it whenever and wherever it shewed signs of want of repair. Lorries that broke down were immediately thrown off the road so that the procession might go on uninterruptedly. In this way the necessary supplies were poured into Verdun continuously for months and the valour and the military skill of our Allies did the rest. This stands out as the greatest achievement of the internal combustion engine in making motor transport one of the most important factors in the war but it is only an illustration of the services it was rendering in lesser degree in all parts of the field.

I have left the case of the submarines to the last. It would hardly be correct to say that it was the internal combustion engine that made them possible. When the French first introduced submarines they used steam, though with indifferent success, and we ourselves are using steam for certain purposes on our largest submarines of the latest type. But it is correct to say that the internal combustion engine first made them practicable. They all use and must use such engines and they are usually though not necessarily of the Diesel type. To answer the requirements of a submarine its engines should be capable of being started in a moment and stopped in a moment and this condition is satisfied by the internal combustion engine alone. But though the value and efficiency of submarines are due to the use of the internal combustion engine it cannot claim the distinction of having made them possible. This belongs to a scientific invention of a yet more peaceful type. I well remember meeting at the Electrical Congress of Paris in 1881 a pale delicate looking man named Gaston Planté who took me into his laboratory to shew me the results of his patient work for years past. He had found that he could electrically oxidize the surface of lead plates in two degrees one more highly oxidized than the other and that when these were used as the plates of a galvanic battery they produced a current—the more highly oxidized plate losing some of its oxygen to the other. But the important part of his discovery was that after the battery had thus run down he could by passing a current from some external source through the battery in the opposite direction restore the plates to their former state so that the battery was ready once more to give out a current.

So long as the current necessary thus to restore his battery could only be derived from some other battery this invention had little value or promise. But the Dynamo had come and by means of it any form of motive power could be made to generate the necessary return current. The Planté battery therefore became a reservoir of electric power which could be filled by the use of motive power derived from any convenient source just as a reservoir of water can be filled from a brook or stream. Now it is necessary that a submarine when submerged in the open sea should be kept moving in order to maintain its longitudinal stability as well as to escape pursuit. The motive force necessary for this must be obtained from some source which requires no air and gives off no products of combustion. An electric current from a battery is the only source possible. The fact that the Planté battery requires recharging from time to time gives rise to no difficulty because the submarine spends most of its life on the surface of the water and can then charge the batteries from its engines. But with regard to the work below the surface, the secondary battery is alone capable of satisfying the necessary requirements of the submarine so that the laboratory work of this quiet scientist made possible the Submarine Menace.

The next great scientific discovery which has proved a formative factor in this War is Wireless Telegraphy. It is rightly regarded as a recent gift of Science to mankind. Yet in its essence it does not differ from the heliographic signals that are still sent from the hills to the plains in India and elsewhere. In both cases waves of electro-magnetic disturbance are sent and received. But when light is the transmitting agency these waves are generated by the heat of the sun and perceived by the human eye. Their path is straight and any obstacle in that path suffices to stop them. These are consequences of the extreme shortness of the waves transmitted. In wireless telegraphy the waves are perhaps a thousand million times as long as the waves of light; they can only be generated or received by special electric machinery and they are not stopped by obstacles in their path. Hence the sender can communicate freely with a station furnished with a receiver adapted to receive his signals just as could be done by the heliograph but with much more certainty and with less risk of the message being intercepted, and these signals can be made to lap round the convex surface of the globe and will doubtless before long be made to reach the Antipodes.

It is not necessary to dwell on the services of wireless telegraphy in the war. Without its assistance aeroplanes could not have produced the profound changes in tactics on land and sea that they did. Indeed it is doubtful whether but for it the labour and cost of bringing heavy artillery into the field would have repaid itself. If you bring heavy ordnance into the field with ranges of from 6 to 30 miles, and mount the guns so that they fire without any disturbing shock and supply them with powder and projectiles so uniform in character that you can rely on the gun repeating its performance with a deviation of at most a few yards in the point where the projectile strikes the ground, as I have described, it is not only an advantage to have effective observation of all that your guns are doing but it becomes an absolute necessity that you should have it in order to get an adequate return for the cost and labour of bringing the guns into the field. This service was rendered by wireless telegraphy.

To airships or long distance aeroplanes, wireless telegraphy has rendered special service. They are furnished with instruments which can not only receive wireless messages but can be made to indicate the directions from which they come. Now you must remember that the civilized parts of the globe are dotted over with powerful wireless installations which are continually pouring off into the ether messages that can be perceived at distances of hundreds of miles. Each such message must have some identifying signal or some characteristic feature to indicate its origin just as the sending station on a telegraphic line must wire its code name along the line to the receiving station. These messages can be picked up by the airships or aeroplanes and their source determined just as a sailor on seeing a flashing or revolving light can identify the lighthouse from which it comes. Thus the airship learns the bearing of a known land station and by repeating such observations can determine its position in space. This is the only known way of navigating trackless fields of air where you are unconscious of the currents in which you are moving even though they may have velocities comparable to your own.

Because I have dwelt on these broad formative factors of this War, it must not be thought that Science has failed us in satisfying its smaller and more special demands. I could spend hours in describing how it has helped us over difficulties of this kind. The sluggishness and unreliability of the compass in our submarines have been met by the adoption of the gyroscope. Special fuses have been designed for anti-airship use which will detonate even when they meet the flimsy covering of an airship. We have learnt how to select our airmen by tests which reveal their powers and their weaknesses to a degree quite unknown to themselves and how to supply them with the oxygen they need at their highest altitudes. When acting as scouts, aeroplanes have had at their command the accuracy that photography gives and their surveys—thanks to the work of Sir William Pope—could be continued when the light was too poor for observation by the naked eye. Powerful but slow-acting incendiary mixtures have been made to burst into full operation with the speed of an explosive. Sounds beyond our power of hearing have been made to convey signals. Alloys have been made to give strength with unheard of lightness. An airman sitting behind a propeller revolving at say 25 times a second has been able to fire through it at the rate of 1000 shots a minute with the same certainty as if it were not there, because the automatic gun which he is working is so controlled through the vibration of a column of liquid that it fires only during the period when the shot can pass clear of the revolving propeller blades although that interval of time must be less than the fiftieth of a second. These are but specimens of what Science can do in special cases. But I have preferred to dwell on what may seem to be less sensational matter because it is not these minor though brilliant inventions which have made the war what it has been. We can imagine them absent and yet the war would have been in essence unchanged—we could not eliminate the internal combustion engine, the secondary battery, wireless telegraphy and the improvements in explosives without going back to a war substantially the same as it would have been in 1870. But as an example of the yeoman service that Science is prepared to render in out-of-the-way lines when called upon to do so, I will spend a few moments in describing sound-ranging.

I have spoken of the excellent system of observation along the front that was carried on by our aeroplanes and captive balloons. But night, cloud and camouflage could do much to evade it and it was therefore desirable to get some means of observation that did not depend on light. Sound was chosen. When the sound of a heavy gun was heard at an observing post a microphone automatically telegraphed it to a head station so that the time of the arrival of the sound at the observing post was known and registered at the head station on a slip of paper moving at a definite rate. Two such records coming from different observing posts gave the difference between the time of the sound arriving at the two observing posts and—as the velocity of sound is known—this gave the difference of the distance of the gun from the two stations and enabled the observers at the head stations to draw on their maps by their instruments a curve on which the gun must be situated. A similar message from a third observing post gave them a second such curve and shewed that the gun must be situated at the point where those curves met. One interesting consequence was the following. Heavy guns are not frequently moved about. They remain in the same position for days and even weeks. So long as a particular gun belonging to the enemy remained in the same position it gave a precisely similar group of three points so that the observers quickly grew to recognize it as though it were a man's signature and thus knowing what particular gun had begun to be busy they could decide on the particular "strafing" that was suitable.

I now turn to the most hateful chapter of the work of Science in War—the introduction of Chemical Warfare. We are slow to realize that an adversary can be utterly destitute of good faith, that the obligations he has undertaken count as nothing in his eyes save as helping to lull the suspicions of others while he is maturing his plans. Hence the first gas attack on April 22nd, 1915 and the five others that followed within little more than a month found us wholly unprepared and it was not until the following September that we were able to retaliate in any way. But our immediate reply was one that did honour to Science. Due to the splendid work of English Chemists a system of defence by gas masks was established in which we were for the greater part of the war far ahead of our adversaries who only succeeded in coming up to us by learning and copying our methods. We produced for ourselves and our Allies no less than 55 millions of these masks and they were the true friend of the soldier and were felt to be such by him in spite of all the annoyance that wearing them necessarily caused. It is impossible to estimate what would have been the destruction caused by toxic gases but for these defensive measures.

The gases selected originally for this detestable warfare were well known chemical reagents of very active properties such as chlorine and phosgene. These were capable of attacking and combining with known substances and thus of being neutralized by the presence of these substances in the respirator of the gas mask. But others were less active in a purely chemical sense. Poisons differ widely in the relation between their chemical and physiological potency. Some of our most intense poisons are so inactive chemically that it is almost impossible to find a chemical test for them. They are too inert chemically to give any marked reaction although physiologically their effect may be to produce instant death. Toxic gases or fumes which are thus incapable of being chemically arrested by means of their readiness to enter into chemical combination must be stopped mechanically in the gas mask by absorption or by the filtration of the air that carries them. But it is evident that no process of this type can be relied on as a protection for a long time if the concentration of the toxic substance in the air be maintained. All defensive means therefore have no further object than the protection of the soldier until he can escape from the dangerous area, which is in fact as unoccupiable by his foe as by himself.

Fortunately the difficulty of maintaining a concentration of toxic substances in the air which is dangerous to life or health is very great. But the possibility of doing so is sufficient to make one take the gloomiest views of the work of Science in connection with the future of this type of warfare. The substances more recently favoured by the belligerents in this war are specially distinguished by their physiological effect. Mustard gas is an example. It cannot be said to be chemically inert but it is not specially active while its physiological action is terrible. A heavy liquid with a high boiling point and giving off a slight amount of very tenuous vapour it can yet render a position untenable for days and produces horrible mischief both in the breathing tract and on the skin for which no specific remedy is known. The many arsenical compounds that have been tried or proposed on the one side or the other have also the characteristic of special physiological virulence and inasmuch as they are but the first fruits of chemical research in this unsavoury domain we may well look forward with foreboding to what it will do in the future.

Thus far I have been treating of the aid that Science gives to the destructiveness of War. There is a brighter side to the picture. It comes to the assistance of the victims of its own devices. But here we come into a wider field of action. The ravages of War are not solely due to the destructiveness of the means of offence employed. Disease is as inseparable an accompaniment of War as wounds or death by violence and it used to be true that in War the loss of life and health due to disease was greater than that due to actual fighting. If this is changed for the better it is due to Science—the old causes are still present. Troops are sent into distant countries with different climates each with its special diseases and are thus placed in unaccustomed surroundings requiring different methods of life, and special hygiene if health is to be maintained. More important still are the unfavourable conditions of life in the field where the troops are crowded together in surroundings which are provocative of disease and fatally adapted to spread it when it appears. To this burden of suffering must be added the perpetual succession of wounds which the increased effectiveness of our weapons of offence makes more and more horrible in their nature and extent. The jagged bits of our high explosive shells with their high velocity, carry deep into the tissues fragments of clothes soaked with all the filth of the trenches, and the torn and mutilated limbs present problems to the surgeons of infinitely more complex a character than those that present themselves in civil life. No wonder that all the resources of modern civilization are taxed beyond their strength in coping with the accumulated mass of sick and wounded that stream in from the battle lines of a war under modern conditions.

But here Science has given no doubtful help in this war. The fruits of the experiments of Pasteur and the deductions his genius led him to draw from them are being reaped. We have learnt that except in the case where some vital organ has been destroyed or fatally injured so that it can no longer perform its functions, the struggle between life and death in the vast proportion of cases is a fight with our omnipresent enemies the microbes. Thanks to the diligent pursuit of knowledge by experiment there has grown up since his time a wealth of knowledge of the nature of these enemies and the means by which Nature defends us from their attacks. In some cases the body responds to the presence of the microbes by making changes in the blood which lead to their extinction and these changes remain after the attack which gave rise to them has passed away and thus the body is left more or less permanently secure from further attacks or to use the consecrated phrase "becomes immune." In other cases where the microbe kills by generating a definite chemical poison, the body generates an equally definite chemical antidote which neutralizes it and keeps the body unharmed until the invader has lost its virulence or has been got rid of by the ordinary methods of defence. In either case the microbe is beaten. Life or death then depends only on the answer to the question whether its progress had or had not done fatal damage before the turn of the tide arrived.

The long and patient study of these subjects by experimental methods to which I have referred has enabled us to come to the aid of Nature along both these lines of defence in this war and brilliant successes have been obtained. Formerly the most feared of camp diseases was typhoid or enteric fever which cost us the lives of so many brave men in the Boer War, and in India was more fatal even than cholera. By inoculating all our troops before they went into the War with vaccine consisting of many millions of the microbes of typhoid fever we induced the same changes in the blood as actually take place in an attack of the fever itself. This could be done without danger of bringing on the disease because fortunately Nature does not distinguish for this purpose between a living and a dead microbe of the same kind so that the vaccines which roused her to her protective efforts were composed of dead microbes which could do no harm. We had proved the efficacy of this treatment in peace time by our experiences in India and elsewhere but its employment in this War put it to a still severer test, and that it was successful is shewn by the fact that typhoid has played but a subordinate part in the losses by disease instead of being the formidable item that one might have anticipated.

Equally brilliant has been the success of the other method, in which we directly assist Nature in her provision of an adequate quantity of the antidote to the poison which the special microbe generates and by which it kills. To do this we have to use Nature's own methods of production of the antidote. Its preparation defies our chemical skill. But we can get her to manufacture it for us by injecting the poison into the blood of some other animal under conditions which make her specially bountiful in generating it. The serum of the blood of such an animal is so rich in the antidote that if it be injected into the veins of the sufferer it reinforces the supplies that Nature affords and counteracts the poison that is being formed by the microbe. It is in this way that diphtheria has lost its worst terrors. A like treatment had been found to be successful in tetanus (lockjaw) before the War. This fearful disease is comparatively rare in civil life but we found to our dismay that it was far from being so in this War. Whether or not it was due to the intensive cultivation in Flanders and Northern France, the dirt carried into wounds was found to be highly charged with tetanus microbes and the mortality from this cause threatened to be heavy. But the remedy bore the strain of this test. The use of the anti-tetanus serum became a routine treatment and proved so successful that (unless it was administered too late, so that the work of the microbe was already too far advanced) it might be relied on to prevent any development of the disease.

This is not a solitary instance of success of this kind. Another example is of grave importance alike in Peace and War. The mysterious disease known as spotted fever has excited great attention from the high mortality attending its sudden and unaccountable outbreaks in isolated localities in this country. It it clearly communicable by infection or contagion and the mortality in spite of careful treatment has been at least 40 per cent. It appeared among our troops and a special study was made of it, resulting in the production of a curative serum which so far as present statistics go seems to reduce the rate of mortality to about one tenth of its former figure.

Time would fail me to enumerate the other advances that Science has made in the special problems of disease that have been imperatively brought to its attention under the stress of the war. It is true perhaps that the theory of the treatment of extensive or deepseated wounds remains still a subject of discussion and divided opinion but there is no doubt of the improvement in practice. Most important also has been the growth of our knowledge of the transmission of disease especially the part played therein by carriers. The crowning triumph in this field is the complete elucidation of the mode of transmission of Bilharzia, a disease with which we were faced through the presence of large contingents of our troops in Lower Egypt. It is a disease which is present in a chronic form in some three fourths of the male population of Lower Egypt, has existed there since the days of the Pharaohs and extends from the South of Africa to Mesopotamia on the one hand and the West Indies on the other. We have obtained full knowledge of its mode of transmission and its life conditions and they are such as point the way to effective action in the direction of its extirpation. If we succeed in checking its spread it will be indirectly due to the strain of the war which makes us alive to the necessity for prompt action and creates not merely a willingness but an eagerness to accept all the aid that Science can give us in dealing with the emergencies that so continually arise and which permit of no delay.

In all these instances both combatants have to a more or less equal degree shared in the help that Science has given. But there is a glaring exception to which I must now refer. All explosives with a few unimportant exceptions depend on the use of Nitrates and until a few years ago these Nitrates were universally obtained from the natural deposits found in Chili. Science then shewed that they could be made directly from the Nitrogen of the atmosphere. Our Government and our Industrials took no heed of these discoveries. It involved less trouble and less expense to continue to get them from Chili and that contented them. It was otherwise with Germany. The German Government realized that to be able to make their Nitrates at home rendered them independent of the command of the sea for a substance essential to their production of explosives. They therefore developed the processes in Germany in factories designed on a huge scale and it was not until these factories were actually at work that they ventured to declare war. But for the existence of those factories the war could not have lasted six months. The existence of these factories changed everything. Throughout the war the Germans were comfortably making their Nitrates at home while we were bringing ours by a perilous journey across the seas from the Pacific coast of South America. That advantage they still retain but it will be an unpardonable act of folly on the part of our Government and our people if it is allowed to exist any longer, now that Peace has set free the man power of the nation and made it possible for us to atone for our past neglect of these scientific discoveries so vitally important to our country's safety in time of War.

To my mind there is one over-mastering lesson to be derived from the contemplation of all that Science has done for War She has made mankind too formidable a being to be permitted to have recourse to it. Uncontrolled indulgence either on the part of a nation or of an individual in the exercise of the powers that Science has placed within its reach is directly fatal to civilization itself. It is easy to criticize the League of Nations and to point out the difficulties and even impossibilities with which it is faced but let us never forget, that some combined action of that type is an imperative necessity. Another such War as this has been would wreck all that Humanity has built up through long ages past with so much toil and patience and would create a well-founded despair of any enduring future. Mankind endowed with all the powers that Science has given him will be self-destructive unless his social instincts, his love and sympathy for his fellow man become sufficiently strong to induce him voluntarily to submit to those powers being fettered when otherwise they would be used for destruction.

CAMBRIDGE: PRINTED BY
J. B. PEACE, M.A.,
AT THE UNIVERSITY PRESS