Tobe brief, it is evident that the bridge-building of modern times—from the Renaissance to our own day—has been nothing more than a long series of experiments from which a good many important matters have been excluded. High artistic qualities were divorced from military forethought by the earlier pontists of the Renaissance;[139]then came the delicate swagger of a fidgety dilettantism, like that which built the Palladian Bridge in Prior Park, aboutA.D.1750; afterwards, by degrees, the industrial spirit began to assert itself; and in 1779 the first metal bridge was built in Europe. How different the history would have been, how much saner and finer, if bridge-builders had taken for their guide the all-sufficient principle that their work must be self-protective, not vulnerable and defenceless. From this principle the most wonderful varied work could have been evolved, generation after generation. By this time there would have been as much difference between an Elizabethan bridge and a modern stone bridge, as between Drake’s “Golden Hind” and a super-Dreadnought. But the sedulous ape has been active everywhere; and Europe to this day is proud when she builds in stone a few bridgesthat seem to be as good as their classic foreparents, though they break away from the classic principle of self-defence.
It is in metal bridges alone that we find a virile growth, a genuine evolution; not often artistic, and as sensitive to bombs as card castles are to a touch from your finger; but yet a great evolution because it represents modern times. If we could summon to earth the spirits of the greatest bridge-builders—Caius Julius Lacer, Apollodorus of Damascus, Isembert, Bénézet, Ammanati, and several others—they would learn nothing much from our stonework, whereas a metal bridge here and there could not fail to strike awe into these spiritual beholders. Even Lacer would be awed by the colossal newness of the Forth Bridge, whose technical inspiration might have come from Vulcan, the god of furnaces, after his annual festival on the 23rd of August. And cannot you imagine what Bénézet and Isembert would say to each other, in swift, excited French, when they gazed up and up at the airy film of road suspended over the wide Menai Straits? This would be enough to convince them that a few recent bridge-builders had forsaken ancient forms in order to give expression to generative ideas.
PONT DE TOURSPONT DE TOURS—A FAMOUS BRIDGE OF THEXVIIICENTURY. IT IS IN KEEPING WITH THE SPIRIT OF WATTEAU
PONT DE TOURS—A FAMOUS BRIDGE OF THEXVIIICENTURY. IT IS IN KEEPING WITH THE SPIRIT OF WATTEAU
The concept of metal bridges may have come to Europe from China. In the seventeenth century Kircher saw and described a Chinese bridge which seems to have been a genuine suspension bridge of metal, a true forerunner of the Pont de la Caille, over the Pass of Usses, and of the immense Pont de Beaucaire, which in four spans unitesBeaucaire to Tarascon, covering a distance of more than 438 metres.[140]Who can explain why backward China has hit upon many fertile ideas before the more enterprising nations? Why has she not learnt to rule the world? Perhaps her body has been too numerous for her brain. On my table lies the photograph of a bridge which may be similar to the one admired by Athanase Kircher. It is an iron swing bridge in Western China, near Auhsien. There are three piers, two of stone, and the other a makeshift of two timber piles joined together at top by a log upon which the footway rests. The carpentry of the footway is primitive: across the long bearing beams, which are not at all thick or heavy, a great many slim laths lie unevenly; and up the middle of the bridge, from end to end, is a narrow path made with long and flat planks which rest upon the transversetimbering. As for the iron suspension, it is a chain of thick and short rods which are linked firmly together. These rods, thus looped at each end and interlocked, run in two lines from abutment to abutment, making a sort of parapet at each side of the bridge. Bamboo rods suspend the footway to the iron chains, which pass over the abutments to be fastened securely on the ground.
There are four abutments, but my photograph shows only one; and it omits also the main thing of all—the means by which the metal chains are anchored. Still, the abutment is entertaining. It is a stone pillar about five feet high, perhaps a little more or less; it seems to be old, and from two holes pierced through it we learn that several experiments were made before the right leverage was obtained. The first hole was too low down, so another was drilled about 12 inches above it, and through this second hole the chain was passed, then tugged down to its anchorage. Even then the suspension was not effective, the hole or “saddle” being still not high enough above the footway, and the builders knew not what to do. Not only was there insufficient space for a third hole, but very few makers of suspension bridges have been reasonable enough to pass their metal chainsover the summitsof stone pillars and towers. The Chinese workmen at Auhsien were not more foolish than many European engineers have been, for their perforated pillars are not a bit worse than the perforated towers through which suspension chains pass at Clifton and at Budapest, not to mention many other familiar examples.So determined were the Chinese to overcome their difficulties without using the summit of their pillar, that they cut away the stone until they came to the second hole or saddle, and then they thrust a lump of iron under the taut chain. Next, to increase the tension still more, they put up a smaller pillar perhaps a yard from the first one, forcing it under the iron rods, which at this point strain downward to their anchorage. Curiously enough, the lesser pillar—a sort of understudy—is used as an architect would employ it: along the top a groove is hollowed, and the chain rests in the groove and then dips down at a sharp angle. Perhaps, then, the smaller pillar is fairly new, while the larger one is old.
TheRev.O. M. Jackson[141]knows this bridge very well; he lived for five years at Auhsien, and on one occasion the whole bridge was washed away by a spate. For months the iron chains lay here and there on the river-bed; and as floods are frequent, and the bridge is not a high one, very little of the workmanship has had a chance of growing hoar. The pillars have the best chance; and I suppose the iron chains are worth saving from the river whenever the bridge is reconstructed.
I have lingered over Auhsien Suspension Bridge not because of its craftsmanship, but because it marks a primitive phase in the evolution of metal bridges. Perhaps the example seen by Kircher was less rude; and perhaps the principle of its construction may have been precisely likethat in the bamboo swing bridges of Western China. In these there are four huge cables of twisted bamboo[142]: two of them carry the footway, while the upper ones serve a double purpose: a strong netting on each side braces them to the lower cables, giving another support to the footway, and forming a sort of hammock a good deal taller than an average man. It is within this deep hammock that everybody walks across a bamboo swing bridge, which in a high wind is as enjoyable as a rowing-boat. At each abutment there is a gabled entrance gate, where the four cables are screwed up.[143]Displace the bamboo cables for iron chains, and we get at once, perhaps, an idea of the bridge that Kircher regarded as “merveilleux.”
As Kircher’s book was published in 1670, an iron bridge ought to have been built in Europe before the middle of the eighteenth century. An attempt to build one was made in 1755 at Lyons, but it failed. An arch was put together in a builder’s yard and then the project was abandoned as too costly! But the idea was handed on somehow to an English ironmaster, Abraham Darby, of Coalbrookdale, who in 1779 won a great success by bridging the Severn with a very useful arch of cast-iron, having a rise of 50 feet, and a span of 100ft.6ins.The cost of it is not known, but the weightof metal employed was 378½ tons. The design is bold, and the arch handsome. Every pontist should get a photograph of Coalbrookdale Bridge. Already it is out of date, and its value as history will not save it from destruction.
A few years later, in 1796, Rowland Burdon followed the example set by Abraham Darby, but not as a mere copyist, his Wearmouth Bridge being an arch of open cast-iron panels, which act as voussoirs. The span is 236 feet, with a rise of 34 feet; the springings are 95 feet above the river-bed; at first the footway was rather narrow, but in 1858 it was widened by Robert Stephenson. Rowland Burdon used 260 tons of iron, and his work cost only £27,000.
Soon afterwards, in a great cast-iron arch thrown over the Spey, Telford made new experiments, and, as Professor Fleeming Jenkin has said, his bridge at Craigellachie marked “a great advance in the conception of what was the safest form in which to apply cast-iron to an arch.” But more than this was expected from an engineer of Telford’s reputation, and nothing more came from him, unfortunately. In fact, Telford divorced his work from the good sense of good design, which Darby and Burdon had endeavoured to respect. At each abutment he put up a silly tower pierced with arrow-slits and armed with battlements, advertising a farce of warlike make-believe which scores of foolish engineers would copy and adapt, while leaving their bridges entirely unfortified.
A bridge here and there is supposed to be all right.Take, for instance, the Forth Bridge, with his 51,000 tons of steel, and his amazing cost, about £3,000,000; he is looked upon as a “safe” bridge, and safe he is if we forget what bombs and shells can do in a few seconds. At each end of this bridge the railway is carried by trivial columns forming the approach viaducts, and these a naval gun would blow to smithereens. A bomb falling upon them from an airship might put the whole bridge out of action. Further, the columns are comically out of scale with those gigantic pyramids of steel bars which counterbalance the centre girders, and yet seem to play at leapfrog in two bounds of 1710ft.each, and in two lesser jumps of 680ft.each. Yes, the Forth Bridge looks formidably alive and active; he is to modern engineering what the Ichthyosaurus became to our knowledge of prehistoric animals: a semi-marine colossus, fit to be kept for ever as a tremendous danger happily extinct.
Several years ago, in the “Builder,” I drew attention to the defenceless character of this huge viaduct over a strategic waterway, and now I return to this topic at the beginning of a war that may well be the most terrible in all history. To-day is the 3rd of August, 1914; and the world knows that Germany has occupied Luxemburg, a neutral State, has poured her troops into Belgium, the naval key of Great Britain, and has violated the French frontier without declaring war. Here is the swift “morality” of lightning. In the strategy of war, non-moral Powers may gain over us a horrible advantage. England talks so much about peaceand honour that felon Germany is able to plan at her ease great military movements of surprise as fateful as victories on stricken fields. Before this little book is published “the black bullets of Destiny” will have been cast in several countries; and not a battle will be won, nor a skirmish fought, without either help or hindrance from those soldiers unprepared that we call viaducts and bridges. Already many have been blown up in Belgium and in Servia; and by night and day, throughout Europe, men are trying to guard every bridge of vital importance to the concentration of troops. Here in England this protection is not always as alert and thorough as it ought to be. I am writing in Hampshire, near by the main line from Aldershot; within a walk of three minutes there is a high railway bridge over a road, and a few hours ago it was unguarded from the road. Yesterday evening, after dark, a German spy could have destroyed it, for I passed under its vault and found no one keeping watch and ward.[144]Instead, I encountered that supine national folly which has withheld our young men from national service, because of the rich liberty which we are supposed to get somehow from cooing claptrap, and Norman Angells, and the future pacification of mankind.
Whatever this fateful war may bring to us and to others, the defenceless bridge will have to be reconsidered; and for this reason its evolution attracts me even now, despite the darkling uncertainty that encompasses every hour of the day. The Forth Bridge, all shatterable bulk and no beautyand grace, does full justice to our industrialism, but yet he belongs, not to the public spirit of Great Britain, but to the spirit of the age everywhere; for in other lands he has a great many rivals not a whit less huge and vulnerable. As an example, we will take the Illinois andSt.Louis Bridge, really a fine work of his kind, dating from 1873. He crosses the Mississippi, which atSt.Louis flows in a single channel 534 yards wide and 8 feet deep at extreme low water. The greatest range between high and low water is 41 feet. There are three ribbed arches of cast steel, the middle one with a span of 520 feet, while the others are 18 feet narrower. If it was worth while for the sake of public convenience to erect this great highway above a wide and dangerous river, it was also worth while for the sake of public convenience that the width of the arches should be determined by the probable dangers to which the bridge would be exposed in commercial strikes and in other wars. Human gunpowder is not a rare thing in the United States of America. The black race there has a population that increases rapidly, and some day it may breed a great soldier, a dark Napoleon, who will find it no difficult task to organise a widespread society of bridge-wreckers. No truisms are more common than unexpected events. Let us then ask whether it would be possible swiftly to repair a metal arch having a span of 520 feet. If not, why build a huge and costly structure with steel-ribbed arches which are much too wide? What if one of them was destroyed at a time when the double railway track over the river, and the wide roadwayabove for other traffic, were necessary to bring reinforcements to a stricken army?
TARN AT MILLAUON THE TARN AT MILLAU IN SOUTHERN FRANCE. THIS DRAWING, A COMPANION PICTURE TO GIRTIN’S “BRIDGNORTH,” REPRESENTS THE BROKEN END OF AN OLD BRIDGE WITH A MILL BUILT ON IT; BEHIND IS AN ARCH OF THE NEW BRIDGE
ON THE TARN AT MILLAU IN SOUTHERN FRANCE. THIS DRAWING, A COMPANION PICTURE TO GIRTIN’S “BRIDGNORTH,” REPRESENTS THE BROKEN END OF AN OLD BRIDGE WITH A MILL BUILT ON IT; BEHIND IS AN ARCH OF THE NEW BRIDGE
These questions were too unmercantile to be considered by the chief engineer, Captain James B. Eads, a very scientific person, who was entirely of a piece with our European pontists. Not a scrap of attention did he pay to military matters. Every account of Captain Eads and his bridge bombards us with technical details. We are expected to gape with admiration because £60 per ton of 2000 lbs. was the price paid for 2500 tons of cast-steel. Wrought-iron in a ton of 2000 lbs. cost £40, and 500 tons at this price were used. Rolled-iron in a ton of 2000 lbs. cost £28, and 1000 tons at this price were employed, together with 200 tons of cast-iron at £16 per ton, the ton in this case being 2240 lbs. Here indeed is a golden target for bombs and for modern artillery!
Every bridge in the United States of America is a target of this sort in one form or another. There are bonfire timber bridges, for example, exceedingly deft and excessively high; sometimes their piers are nothing more than large wooden frames piled one on top of another, up and up and up, till at last they are tall enough to be known as great sky-ticklers. One example is 234 feet high. It is the great Portage Bridge spanning the Genesee River, in the State of New York, on a railroad between New York and Buffalo. It looks like a miracle of carpentry, this wonderful bridge of frames; its length is 240 metres, and the piers—sixteen romantic scaffoldings—form immense triangles with flattenedsummits upon which a double gallery rests as a firm support for the railway. Each scaffolding rises from a pile of masonry nine metres higher than water-level, so that floods do not break their force against the timber frames. Good heavens above, how this bridge would burn! But it has a quite modern fascination: its cost of production wascheap!—cheap in comparison with the estimated price of a stone bridge with the same length and aviated height. This wooden structure cost about £36,000, for the pride of trade likes to pay as little as possible for the largest amount of very perishable insecurity.
Then, of course, there are sky-tickling metal bridges, and these spindle-shanked devotees of peace are popular also in Canada. All this work is nothing but industrial engineering, like the mighty bridges at New York, though these do try to look somewhat architectural. One specimen, indeed, a vast structure called the New Manhattan Bridge, has marvellously long suspension cables which donotgothrougha tower or gateway; they actually passovertheir supports in a logical manner. What a blessing! On the other hand, Brooklyn Bridge at New York has the same mistake as our suspension bridge at Clifton (p.346); and the pierced towers, each with two lancet-shaped openings, are affected and trivial. Brooklyn Bridge has a total length of nearly 1141 yards, and between the two towers there is a span of 1595 feet. The roadway is upheld by four galvanised steel cables not less than sixteen inches in diameter. Think of that! Try to imagine a span 1595 feet wide! Suppose anairship crippled it with some large bombs, how in the world could repairs be made?
Briefly, then, modern bridges everywhere are anti-social. When war is afoot, they imperil the best-made plans of strategists; and even in strikes they have to be guarded by soldiers, as if they were convents where dethroned queens lived unhappily with suffragette princesses. Though we have lived for many years on the brink of war, every highway in Europe as in America is at the mercy of bridge-wreckers. Is it not dumbfounding that no respect has been paid anywhere to the social guardianship that bridges and roads ought to perform? Why has this all-important matter been forgotten? It has been made memorable a great many times in history, ever since Horatius Cocles and his two companions held the Pons Sublicius against the whole Etruscan Army under Porsena,—a lesson never forgotten by Roman citizens.
When Lord Surrey, before the battle of Flodden Field, outwitted the Scotch by throwing his army across the Till by the beautiful old Twizel Bridge; or when Charles the Second, routed at Worcester, fled by Old Pershore Bridge into the Bredon Hills, England received one of many warnings that a secure passage over rivers might be to her at any moment as valuable as an army corps. Why has she failed to take this lesson to heart? No railway is protected by two or three branch lines over an important river, so that two or three bridges—not near together, but separated by a mile or two—would have to be destroyed before the river would beclosed to the passage of troops and of food supplies. Understudy lines and bridges would be invaluable to defensive strategy.
More than a century has gone over since Perronet warned France that bridges across great rivers ought to be of a kind which would facilitate makeshift repairs after mishaps in war. He spoke earnestly, but in vain; for the conception of trade as war had not yet been forced upon the world by modernised industrialism, with its civil strikes and its international competitions. If Perronet had been able to add his foresight to the great traditions of thePonts et Chaussées, his countrymen, probably, would have been loyal to his excellent advice, because the French have a Roman logic and they love their roads and bridges. But in France, as in other countries, a craze for engineering feats took possession of the public mind, excluding many other considerations. I know not how many perishable bridges exist at this moment in France, but I can give the figures for 1873. In that year there were one thousand nine hundred and eighty-two. Their total length was 106 kilometres, and their total cost was 286,507,761 francs. Here are some of the more expensiveexamples:—
Compare these figures with those of some Britishbridges:—
We see, then, that the bridges of civilization, when viewed merely as financial investments, are valuable enough to be made self-defensive.[145]Yet it happens that I am the only writer who has tried to draw public attention to the ease with which any bridge in England could be crippled. And the trouble is that engineers hold the field, because the man of business finds in their work a hard routine that looks practical and mercantile. What we need is the influence of architects. For capable architects have the genius of artists, and when artists give their minds to practical affairs they show a range of common sense that men of trade rarelyequal. It is in their nature to look at a question from all sides till they see it amply and as a whole, while men of trade isolate two or three things from many, and accept them tenaciously as the only things that merit attention.
But in our social life and strife there are certain newcomers that will compel the world to reconsider its wrong attitude to bridge-building. I refer to airships and to aviation, with their threatened wars from overhead. A good many bridges over strategical waterways can be displaced by tunnels, but many others must be armoured with cone-shaped roofs. Art and science have done wonderful things for the modern battleship, and now—now they must invent and perfect a new battle-bridge, fit to protect arterial highways from “progress.”
It is the morning of the 4th of August, and I have just read the latest war news. The whole life of Europe is a note of interrogation, infinitely sinister and tragic. What is destined to happen? Which nations are doomed to perish? What navy will go down into the deep? Which airmen will make the most successful attacks on those bridges that govern the distribution of food supplies? Will the equity of Europe triumph, or will German felony succeed?
Three months have passed, and I add a few lines to my page proofs. Many events have illustrated and confirmedthe main arguments of this monograph. Everywhere defenceless bridges have been the cause of much anxiety, and dozens have been destroyed because they could not be turned into rearguard defences. Wellington said that his sappers in five minutes could blow up a modern bridge. In the present campaign sappers have done this work under fire, mining strategic highways being a simple job. How ludicrously tragic is the contrast between the building of a modern bridge and its easy demolition! A little common sense would have flanked each entrance with a Brialmont fort, and would have given to the bridge itself an armoured efficiency. Every bridge between the French frontiers and Paris ought to have been as effective as a super-Dreadnought. So the use of battleship steel in bridge-building is one thing that engineers must consider with the utmost care after Germany has been overthrown. If they do no more than follow their foolish old routine, then their work will be a crime against patriotism.
In other respects the Great War has been a wondrous varied surprise, bringing weakness to the strong and power to the weak. Germany has been humbled both by little Belgium and by the little British army; her prestige has dwindled so much that fighting mechanisms are regarded no longer as superior to fighting men. In true discipline there is an art of humane pride, and Germany has crushed it out of her automatic battalions, preferring an organised cruelty as insensitive as a railway accident, and a system of lying that rivals Munchausen’s. Even her learnedprofessors fill current history with explosive lies, just as her seamen before the declaration of hostilities dropped mines in the North Sea from trawlers that flew the British flag. If victory could be won by vile misdeeds, Germany would be unconquerable. Never before has a powerful nation been so corrupted by forty years of unscrupulous vainglory. Her ambition is to Europe what cancer is to a human body—a ravaging disease which may break out again after the best surgeons have finished their work. Already she has tried to postpone the operation by making overtures to stop the necessary bloodshed. Germany wants to give in before the British Empire can put a million troops in the field, because she knows not only that Allies often quarrel during the negotiations that rearrange maps, but that such quarrels occur most often when a great country has a little army in absolute antagonism with widespread interests of a vital sort. And this, moreover, is not the only peril. In the British Isles many thousands of peace-fanatics bide their time; some of them are active already as pro-Germans; many others declare that they have no wish to humble the German people, who now approve every act of a Hunnish despotism elaborated by their Government; and when our British sentimentalists, aided by several Radical newspapers, begin a campaign of shrieking claptrap, a just resentment will be felt by France and Russia. So the warfare of diplomacy may be more dangerous to the Allies than the warfare of stricken fields. We must wait and see. But the present position confirmsanother argument in this monograph: namely, that those who decline to see the perpetual strife that reigns in all human affairs, and who babble in a routine of fixed ideas about the illusion called peace, are quite as perilous to a country as were the creeds of bloodshed which many German writers advertised, taking liberties with the ingenuous pacifism coddled by British Governments.
Let us delete from every dictionary the lying word peace; and let us believe firmly in the simple truth that strife everywhere is the historian of life. The strife in all its phases ought to be well trained and chivalric, of course; and it needs vast improvements in the campaigns of business warfare. Every slum, for example, is very much worse than the longest battle with firearms, because it endures for ages; and what chivalry in the wars of trade is as noble as that which grants to young men the privilege of defending the old age of their country from danger and dishonour?
[136]It is worth noting, as an example of British apathy in home defence, that the railway from Aldershot toward Southampton is for many miles a single line only, and that it passes over a good many gimcrack bridges and between some narrow and steep embankments, as in the neighbourhood of Medstead. The line is an open trap; it could be shut up in a dozen places by a few intelligent spies, if spying did not generate an excessive caution as futile as cowardice.
[137]This bridge is 250 metres long, and the five arches have equal spans of 40 metres. Perronet died in 1791, at the age of eighty-three, and we study his best work at Mantes, Orléans, Nogent-sur-Seine, Pont-Saint-Maxence, Château-Thierry, and Neuilly-sur-Seine.
[138]His words run as follows: “I think that it may be prudent, when designing bridges for rivers of great width, to introduce some strong piers, which in case of need may serve as abutments, putting them at distances of three or four arches apart. Moreover, this arrangement will enable us to construct long bridges in different parts successively, and each part may be considered as a complete bridge, having its own independent abutments; but strict care should be taken not to contract the beds of rivers by using too many thick piers.” One of Perronet’s immediate predecessors, the engineer Gabriel, built a bridge of this sort, over the Loire at Blois. He spaced his plan into eleven fine arches, and erected two abutment piers, placing them at four bays from each bankside, and leaving three bays between them. By this means his bridge was divided into three independent parts.
[139]Examples: See the index under the headings“Trezzo,”“Ticino,”“Pavia,”and“Ammanati’s Trinità at Florence.”
[140]See Degrand’s“Ponts en Maçonnerie,”Tom.2,p.24, note 3. See also Dalquié’s translation of Kircher’s book, published at Amsterdam in 1670. There is a reference to iron in a bridge onp.288, but Degrand’s information must be taken from the following passage:“L’on voit un pont dans la Province de Junnan, qu’on a basti sur un torrent, lequel roule ses flots impetueux dans le panchant d’une profonde vallée. C’est un commun sentiment qu’il fût basti en l’an 65 après la naissance de Jesus Christ par l’ordre de l’Empereur Mingus, sorti de la famille Hame; il n’est pas fait de brique ny de pierre; mais on a attaché de grosses chaisnes [chaînes] à ces deux montagnes qui vont d’une extremité à l’autre, au-dessus desquelles on a mis des ais pour faciliter le passage des voyageurs. Ce pont, qui a vingt chaisnes, a 20 perches de long qui font 140 pieds: l’on dit que quand beaucoup de personnes passent dessus, ou qu’il y a quelque grand fardeau, il branle si fort qu’il fait peur à ceux qui y sont”(p.289). This description is vivid, and M. Degrand regards the chains as chains of iron. He says:“Kircher mentionne l’existence ... d’un pont composé de chaînes de fer supportant, en travers d’une vallée profonde, un tablier en charpente d’une grande longueur, c’est-à-dire un véritable pont suspendu, ayant précédé sans doute de plusieurs siècles les ponts du même genre construits à l’époque moderne en Europe et aux États-Unis.”
[141]See Index for other references to Mr. Jackson.
[142]Marco Polo describes very well how the bamboo in China is twisted or plaited into cordage. He says: “They have canes of the length of fifteen paces, which they split, in their whole length, into very thin pieces, and these, by twisting them together, they form into ropes three hundred paces long. So skilfully are they manufactured, that they are equal in strength to cordage made of hemp.”
[143]I take this description from two photographs belonging to the Church Missionary Society.
[144]On the 4th of August this important bridge was guarded by Territorials.
[145]Notallbridges should be military, of course, since those near a frontier may have to be destroyed at a moment’s notice in order to check the advance of a surprise attack.