Sunset (magazine)/Volume 32/Can the Panama Canal be destroyed from the air?
This remarkable photograph was taken by Ray A. Duhem from the hydro-aeroplane of the noted aviator, Robert G. Fowler. Under unusual difficulties Fowler made a daring flight across the Isthmus from the Pacific to the Atlantic, so far the only aviator to make the journey. Shortly afterward, President Wilson issued an executive order forbidding such, flights, under heavy penalty. The photographs made on this flight, in themselves a notable achievement in motion photography, are probably the only pictures that will ever be taken of the Canal from the air, except for purposes of war. This page in Sunset Magazine is the first publication of any of the photographic records of that unique flight.
Can the Panama Canal Be Destroyed From the Air?
By RILEY E. SCOTT
Colonel Goethals is reported as saying, in February: "The Canal fortifications are entirely adequate and I do not think there is the slightest danger of the Canal being captured by any enemy." The great canal builder might have added, in a paraphrase of Paul Revere: "None, if by land, and none, if by sea." But how, if by air? The man who asks this question in the following article is a graduate of West Point and for several years has made a special study of the aeroplane as an instrument of warfare. He is the inventor of a scientific range-finder for accurately dropping bombs from aeroplanes and his device has been adopted by several European armies. In 1912, in competition with the crack military aviators of France, under the auspices of the French army, he won all prizes offered for dropping bombs from aeroplanes. In Europe he is considered an authority as well as a pioneer in this field. At this time he is conducting experiments at San Diego for the War Department, dropping explosives from an aeroplane under war conditions. Mr. Scott believes that the United States, having fortified the Canal against attack by land and sea, must eventually protect it from attack by an aerial foe.
THE Panama Canal—the most stupendous engineering feat of an engineering age—is nearing completion. The shriek and hiss of a thousand locomotives, the monotonous purr of compressed-air drills, the boom of blasts and the creak and groan of giant cranes and shovels have almost ceased. Soon the healing hand of Nature will bind up the scars of conflict and the commerce of a world will float between picturesque tropical hills. Naturally, the American people are proud of the job and proud of the men who have consummated this great undertaking without hitch and without taint of graft or scandal, where hundreds of millions have been involved. It is a magnificent achievement and we have reason to be proud.
The most vital and probably the most vulnerable points of the Canal are the great locks. These have dividing walls, double gates, operated by delicate electrical machinery, emergency dams and floating caissons—all offering an admirable and non-coverable target from the air
Canal has been constructed largely to remedy this weakness.
As early as 1901, the Isthmian Canal Commission said in its report: "It is the opinion of the Commission that a neutral canal, operated and controlled by American citizens, would materially add to the military strength of the United States; that a canal, whether neutral or not, controlled by foreigners, would be a source of weakness to the United States, rather than of strength; and that a canal not neutral, to be defended by the United States, whether by fortifications by land, or by the navy at sea, would be a source of weakness."
Whether right or wrong, we have decided to make the Canal non-neutral and to strongly fortify it. Thus the Canal be comes probably the most important strategic part of our coast-line, and it does not require military training to see that, in case of war with a first-class power, the enemy would very likely strike first at the Canal and attempt to keep our naval forces divided. Even now, it is necessary to keep a fleet on each ocean and, doubtless, after the Canal is opened, these fleets will be greatly augmented and of about equal strength.
The main fortifications are being placed on islands near the Pacific entrance to the Canal and on a headland near the Atlantic entrance, in order that an enemy's fleet may not approach the shore within bombarding distance of the locks and dams. These fortifications are among the strongest in the world, and comprise batteries of 14-inch mortars and disappearing guns, supplemented with a 16-inch gun, the most powerful weapon of any army. Auxiliary batteries of light rapid-fire guns probably will be located on the hills near the locks and dams, as a precaution against land attacks. In addition to troops to man the fortifications, it will undoubtedly be necessary to maintain a large force of troops there on a war footing, in order to police the Canal Zone and to provide against attacks by land, for modern warfare strikes quickly and it might be difficult or impossible to transport troops from the United States, after the breaking out of hostilities. Our neighbors to the north and south of the Canal are none too friendly and, if the Zone were not thoroughly policed, partisans of the enemy might produce havoc to locks and dams with dynamite. Colonel Goethals, 
The Cucuracha slide, in the Culebra cut, is ample proof of the unstable nature of the volcanic soil of the Cut. It presents an effective barrier across the Canal, created suddenly and removed only by long effort. Could such a slide be created from the air? The means already exist
it is said, estimates the number of troops eventually necessary for this purpose as 20,000, which will require the construction of one or more of the largest army posts in our service.
For the past six years, at least, the problem of fortifying the Panama Canal has engaged the attention of our ablest military authorities and, naturally, every precaution has been taken to insure, as far as possible, its impregnability. But, during this time, a new factor in warfare has gradually been developed—a factor whose vast importance is just beginning to be realized by even the most progressive strategists and tacticians. I refer to what the French call "the Fourth Arm"—the aeroplane.
When we stop to consider it, the progress that aviation has made during the past five years is simply amazing. At the end of 1908, not over half a dozen machines were flying, with a duration record of about an hour and a half, a speed of some forty miles per hour and a height record of 320 feet. At this writing, the duration record is over sixteen hours without landing, a height of three and eight-tenths miles has been attained, a speed record of 126 miles per hour has been made, continents have been crossed, seas have been traversed, mountain ranges and deserts have been flown over and the number of machines is legion. France alone has over 800 military aeroplanes ready for service and is making a desperate effort to maintain the mastery of the air; while Germany, Russia, Great Britain, Austria, Italy and Japan are training aviators and providing machines as fast as possible. In short, military experts are coming to realize that the aeroplane is not only a factor in warfare, but may become a decisive factor.
It is not of their use as "the eyes of the army" in securing and transmitting in formation that I wish to speak here, how ever, but of a newer and, some believe, more important development—as carriers of incendiary bombs and high explosives.
Over a year ago, in France, the writer demonstrated, beyond doubt, that remarkable accuracy can be attained in dropping bombs from an aeroplane by placing twelve out of fifteen bombs within a square of about 120 feet from a height of over one half mile and at a speed of nearly a mile a 
minute. During these experiments, a weight of 225 pounds was dropped at a single time from a light machine, and, at the present time, aeroplanes exist that are capable of carrying and dropping bombs of five hundred pounds without difficulty. It is safe to predict that the next year or two will develop machines capable of carrying one thousand pounds of high explosives.
While other nations are straining every resource in developing military aeronautics; while secret experiments are being made in dropping bombs and firing at aerial targets; while aeroplanes are being armored and equipped with rapid-fire guns; while the latest dreadnaughts are being designed to carry aeroplanes and have their stacks and other vulnerable parts screened from aerial attack; in short, while millions are being spent in developing what a noted tactician has called the greatest military invention since gunpowder, we, the United States, are doing practically nothing. In this respect, as in several others, we are totally unprepared for war.their stacks and other vulnerable
Without discussing the possibility of destroying our coastal cities—even the capital itself—by aeroplanes from an enemy's fleet, let us consider the vulnerability of the Panama Canal from the air. This discussion assumes that, in the near future, battleships and cruisers will be equipped with aeroplanes, which assumption is
supported by the opinions of high naval authorities.
A study of the Canal reveals to us several vital and vulnerable points which, in the writer's opinion, could easily be destroyed from the air. The most vital and probably the most vulnerable of these are the great concrete locks which will lift vessels over the continental divide. They are six in number—three at Gatun, about eight miles from deep water on the Atlantic side of the Canal, and three at the west end of Culebra Cut, about the same distance from the Pacific.
The lock-gates are colossal built-up steel leaves, thick enough to drive an automobile on top. They are mounted in pairs and are opened and closed by electrical machinery. The upper gates of each lock are double, as a precaution against accident, and have an ingenious arrangement of emergency dams and floating steel caissons, designed to stem the torrent, in case a gate should be smashed, and to allow the gate to be repaired. These locks—especially the double gates, emergency dams and floating caissons—offer an admirable target from the air.
Gatun Dam is built across the valley of the Chagres river, one and one-half miles, and is buttressed at either end by the hills. Its most vulnerable part, outside of the locks, is naturally the "Spillway"—a weir twelve hundred feet long with a slope three hundred feet in width over which the surplus
Culebra Cut is an immense trench, nine miles long, cut through the back-bone of the Isthmus, and has a minimum width of three hundred feet at the bottom and an average depth of one hundred and twenty feet. Its greatest depth is about three hundred and seventy-five feet at the water shed between the two oceans. Immense slides have frequently occurred in the cut, due to the peculiarly unstable nature of the soil, which is of volcanic origin. Also, some of the lower layers are so soft that they have been squeezed out by the weight above. These slides have not only greatly interfered with the construction work, but, it is feared, may seriously embarrass the operation of the Canal.
Beyond Culebra are three double locks, as before mentioned, and also two dams forming a small artificial lake. Further on, near the Pacific end of the Canal, is the American town of Balboa, where wharves, piers, warehouses and sheds for merchandise and extensive railway yards will be located.
These, in brief, are the most vital parts of the Canal, scattered along a route of about fifty miles from deep water to deep water. The pertinent question of this discussion is, can any or all of them be destroyed from the air? To which the writer unhesitatingly replies in the affirmative, all of them. The means already exist— powerful aeroplanes, accurate range-finding instruments, high explosives that can be handled safely, audacious pilots—to effect such destruction, but, for argument's sake, let us allow five years for the application and improvement of these means.
Suppose that war has been declared between the United States and one or more first-class European powers and that the American fleet is divided on the two oceans. Such a war would, in the first stages, at least, be a naval war and it would surely be the policy of the enemy to keep our fleet divided and to strike each division separately. In order to do that, the enemy would quickly mass his naval strength in the Caribbean and attempt to destroy the Canal.
Granting that the fortifications in process of construction are sufficient to keep any probable combination of fleets at bay, we will suppose that the enemy decides to bombard the Canal from the air. Maneuvering just outside of the range of the big guns of the forts, the bomb-carrying aeroplanes are assembled and launched, each machine carrying, say, five hundred pounds of high explosive. Each aviator is given a particular target, whose location and elevation above sea-level are known.
Suppose that there are twenty aeroplanes and that it is decided to concentrate the fire on the upper Gatun lock. The distance from the fleet to the locks would be some thirty miles, a half hour's flight. Circling around the fleet until a height of a mile or over is reached, each aviator, in turn, speeds toward the locks and places his charge more or less accurately upon the target. Assuming that half of the bombs are accurately placed, is it not reasonable to suppose that two and one-half tons of high explosive would play havoc with the double gates, emergency dams and floating caissons, not to speak of the outer and middle walls of the locks?
In the meantime, other machines have been taken from the holds and assembled and are ready to take the places of the units that have gone down in the fight. Within three or four hours, the air fleet, re-assembled and re-inforced, is again on its way, with the power-house and the Spillway gates as objectives. A few well placed bombs would undoubtedly wreck the power house and, the writer believes, put the Spillway-gates out of commission and seriously injure the weir itself.
Supposing that the enemy's fleet arrived during the night and that the first attack is made at daybreak, a single day would be sufficient to attack all vital points as far as the western locks. Culebra Cut would undoubtedly make a good target, providing the enemy had information concerning the points where slides were most likely to occur, which he probably would. By placing several tons of explosives where the walls are weakest, it is quite probable that a serious slide would be produced. If the slide were at all bad, it would stop traffic 
Fort Winfield Scott stand beside the Golden Gate at its narrowest part. Its cannon have long since been removed and the old fort is but a picturesque landmark, the haunt of lovers and the martial inspiration of small boys on happy Saturdays. The bristling breastworks which top the hill above its harmless ramparts would be quite as useless against the marksmen of the air
At Hunter's Point, on the southern edge of San Francisco, on the inner harbor, elaborate plans are under way for increased activity in the care and culture of men-of-war
From this shore the "Oregon" slid into the water and from here she made the famous journey that spurred the United States to the building of the Panama Canal
Warships at temporary rest in the most secluded harbor of the world, or dry-docked for emergency repairs along the Sequestered shores of inland waters, may face unequal and hopeless battle with aerial enemies unless both ships and shores are provided with adequate fleets of aerial destroyers, armed to repel invasion from the air and swifter in flight than the ammunition-laden emissaries from hostile ships off-shore
But why continue? We may rest assured that the enemy would make the destruction as complete as possible, under the circumstances. If it should take a whole day to batter down a single lock and if all the machines should be lost in the fight, would not the results justify the price paid?
But, you ask, is it not possible to bring down an aeroplane from a height of a mile by artillery or rifle fire? Opinion is divided on that point, but many authorities be lieve that it would be extremely difficult. The latest high-powered, small-winged ma chine offers a very elusive target when fly ing at a height of a mile at speeds of over a mile a minute. Moreover, recent experiments with transparent wing-coverings indicate that machines may be made almost invisible at even moderate heights. Undoubtedly, an occasional machine could be brought down at great expense of ammunition, but, so far, experiments along these lines have not been very satisfactory. The writer remembers watching French artillery firing at a free balloon floating in a stiff wind over the plains at Mourmelon, but the gas bag floated out of sight without mishap.
It will probably be necessary to fight aeroplanes with aeroplanes. For example, if we should have a preponderating air fleet of fast machines on the Isthmus, lightly armored underneath as a protection against rifle fire and armed with rapid-fire guns, it would be possible to meet and fly above the heavier, more slowly moving bomb-carriers and pick them off, one by one. The aerial battle of the future is not an improbability, and the writer ventures to predict that many a deed of heroism and daring will take place in the blue above contending armies.
Consider, for a moment, an enemy's fleet lying off New York, San Francisco or other large coastal city. A fleet of hostile aeroplanes, flying at a height of two miles, if necessary, and carrying high-explosive and incendiary bombs, could soon produce havoc in the business district, probably starting a conflagration that could not be checked. No great accuracy would be needed in the congested areas, and the loss of life from fire, high-explosive bombs and panic would be appalling. Without aerial defense, such a bombardment could be continued until the city were completely destroyed. Of what use would our present costly fortifications be, under such circumstances?
Has the picture been painted too strongly? The writer does not think so—that, however, is for others to. decide. He does not wish to be taken as an alarmist, but asks that the case be considered in the light of present aeronautical development and of what we may reasonably expect in the future. He does not wish to say that the danger is imminent, but considers it his duty to warn his countrymen that, in his opinion, a real menace does exist and that little has been done, so far, to meet it. Last year, six great powers spent nearly $25,000,ooo on military aeronautics, France leading with nearly eight millions and Japan forming the sixth with a million, while our beggarly appropriation was $140,000. Is it to be supposed that those nations, already overburdened with taxation, are spending this money foolishly? Nations, as well as individuals, may be "penny wise and pound foolish." Are we, in this case?
Within a decade after the terrible Russo-Japanese and Boer wars and on the morrow after the fratricidal Balkan struggle, while other nations are feverishly adding to military and naval armaments, is it wise to lull ourselves to sleep with melodies of world-peace? With more serious inter national questions than any other nation—the Panama Canal Policy, the Mexican Situation, the Japanese Alien Question, the enforcement of the Monroe Doctrine—is it not imperative that we be thoroughly prepared? Is that not the surest way of guaranteeing peace? All the world knows that, in our recent unpleasantness with a decadent power, we were fortunate rather than formidable. If, in the future, we should lie prostrate at a powerful enemy's feet, whose fault will it be? Surely not the fault of our brave officer-aviators who have begged Congress for a loaf and have been given a stone!