The Dominion of the Air Part 8

It seemed as if the travellers would have to face the chance of crossing the Channel, and while, already in the car, they were actually discussing this point, their restraining rope broke, and they were launched unceremoniously into the skies. This occasioned an unexpected lurch to the car, which threw Mr. Glaisher among his instruments, to the immediate destruction of some of them.

Another result of this abrupt departure was a very rapid rise, which took the balloon a height of 3,000 feet in three minutes' s.p.a.ce, and another 4,000 feet higher in six minutes more. Seven thousand feet vertically in nine minutes is fast pace; but the voyagers were to know higher speed yet that day when the vertical motion was to be in the reverse and wrong direction. At the height now reached they were in cloud, and while thus enveloped the temperature, as often happens, remained practically stationary at about 32 degrees, while that of the dew point increased several degrees. But, on pa.s.sing out of the cloud, the two temperatures were very suddenly separated, the latter decreasing rapidly under a deep blue upper sky that was now without a cloud.

Shortly after this the temperature dropped suddenly some 8 degrees, and then, during the next 12,000 feet, crept slowly down by small stages.

Presently the balloon, reaching more than twenty thousand feet, or, roughly, four miles, and still ascending, the thermometer was taken with small fits of rising and falling alternately till an alt.i.tude of 24,000 feet was recorded, at which point other and more serious matters intruded themselves.

The earth had been for a considerable time lost to view, and the rate and direction of recent progress had become merely conjectural. What might be taking place in these obscured and lofty regions? It would be as well to discover. So the valve was opened rather freely, with the result that the balloon dropped a mile in three minutes. Then another mile slower, by a shade. Then at 12,000 feet a cloud layer was reached, and shortly after the voyagers broke through into the clear below.

At that moment Mr. Glaisher, who was busy with his instruments, heard Mr. c.o.xwell make an exclamation which caused him to look over the car, and he writes, "The sea seemed to be under us. Mr. c.o.xwell again exclaimed, 'There's not a moment to spare: we must save the land at all risks. Leave the instruments.' Mr. c.o.xwell almost hung to the valve line, and told me to do the same, and not to mind its cutting my hand.

It was a bold decision opening the valve in this way, and it was boldly carried out." As may be supposed, the bold decision ended with a crash.

The whole time of descending the four and a quarter miles was a quarter of an hour, the last two miles taking four minutes only. For all that, there was no penalty beyond a few bruises and the wrecking of the instruments, and when land was reached there was no rebound; the balloon simply lay inert hard by the margin of the sea. This terrific experience in its salient details is strangely similar to that already recorded by Albert Smith.

In further experimental labours conducted during the summer of this year, many interesting facts stand out prominently among a voluminous ma.s.s of observations. In an ascent in an east wind from the Crystal Palace in early July it was found that the upper limit of that wind was reached at 2,400 feet, at which level an air-stream from the north was encountered; but at 3,000 feet higher the wind again changed to a current from the N.N.W. At the height, then, of little more than half a mile, these upper currents were travelling leisurely; but what was more noteworthy was their humidity, which greatly increased with alt.i.tude, and a fact which may often be noted here obtruded itself, namely, when the aeronauts were at the upperlimits of the east wind, flat-bottomed c.u.mulus clouds were floating at their level. These clouds were entirely within the influence of the upper or north wind, so that their under sides were in contact with the east wind, i.e. with a much drier air, which at once dissipated all vapour in contact with it, and thus presented the appearance of flat-bottomed clouds. It is a common experience to find the lower surface of a cloud mowed off flat by an east wind blowing beneath it.

At the end of June a voyage from Wolverton was accomplished, which yielded remarkable results of much real value and interest. The previous night had been perfectly calm, and through nearly the whole morning the sun shone in a clear blue sky, without a symptom of wind or coming change. Shortly before noon, however, clouds appeared aloft, and the sky a.s.sumed an altered aspect. Then the state of things quickly changed.

Wind currents reached the earth blowing strongly, and the half-filled balloon began to lurch to such an extent that the inflation could only with difficulty be proceeded with. Fifty men were unable to hold it in sufficient restraint to prevent rude b.u.mping of the car on the ground, and when, at length, arrangements were complete and release effected, rapid discharge of ballast alone saved collision with neighbouring buildings.

It was now that the disturbance overhead came under investigation; and, considering the short period it had been in progress, proved most remarkable, the more so the further it was explored. At 4,000 feet they plunged into the cloud canopy, through which as it was painfully cold, they, sought to penetrate into the clear above, feeling confident of finding themselves, according to their usual experience, in bright blue sky, with the sun brilliantly shining. On the contrary, however, the region they now entered was further obscured with another canopy of cloud far up. It was while they were traversing this clear interval that a sound unwonted in balloon travel a.s.sailed their ears. This was the "sighing, or rather moaning, of the wind as preceding a storm." Rustling of the silk within the cordage is often heard aloft, being due to expansion of gas or similar cause; but the aeronauts soon convinced themselves that what they heard was attributable to nothing else than the actual conflict of air currents beneath. Then they reached fog--a dry fog--and, pa.s.sing through it, entered a further fog, but wetting this time, and within the next 1,000 feet they were once again in fog that was dry; and then, reaching three miles high and seeing struggling sunbeams, they looked around and saw cloud everywhere, below, above, and far clouds on their own level. The whole sky had filled in most completely since the hours but recently pa.s.sed, when they had been expatiating on the perfect serenity of the empty heavens.

Still they climbed upwards, and in the next 2,000 feet had entered further fog, dry at first, but turning wetter as they rose. At four miles high they found themselves on a level with clouds, whose dark ma.s.ses and fringed edges proved them to be veritable rain clouds; and, while still observing them, the fog surged up again and shut out the view, and by the time they had surmounted it they were no less than 23,000 feet up, or higher than the loftiest of the Andes. Even here, with cloud ma.s.ses still piling high overhead, the eager observer, bent on further quests, was for pursuing the voyage; but Mr. c.o.xwell interposed with an emphatic, "Too short of sand!" and the downward journey had to be commenced. Then phenomena similar to those already described were experienced again--fog banks (sometimes wet, sometimes dry), rain showers, and cloud strata of piercing cold. Presently, too, a new wonder for a midsummer afternoon--a snow scene all around, and spicules of ice settling and remaining frozen on the coatsleeve. Finally dropping to earth helplessly through the last 5,000 feet, with all ballast spent, Ely Cathedral was pa.s.sed at close quarters; yet even that vast pile was hidden in the gloom that now lay over all the land.

It was just a month later, and day broke with thoroughly dirty weather, a heavy sky, and falling showers. This was the day of all others that Mr. Glaisher was waiting for, having determined on making special investigations concerning the formation of rain in the clouds themselves. It had long been noticed that, in an ordinary way, if there be two rain gauges placed, one near the surface of the ground, and another at a somewhat higher elevation, then the lower gauge will collect most water. Does, then, rain condense in some appreciable quant.i.ty out of the lowest level? Again, during rain, is the air saturated completely, and what regulates the quality of rainfall, for rain sometimes falls in large drops and sometimes in minute particles?

These were questions which Mr. Glaisher sought to solve, and there was another.

Charles Green had stated as his conviction that whenever rain was falling from an overcast sky there would always be found a higher canopy of cloud over-hanging the lower stratum. On the day, then, which we are now describing, Mr. Glaisher wished to put this his theory to the test; and, if correct, then he desired to measure the s.p.a.ce between the cloud layers, to gauge their thickness, and to see if above the second stratum the sun was shining. The main details of the ascent read thus:--

In ten seconds they were in mist, and in ten seconds more were level with the cloud. At 1,200 feet they were out of the rain, though not yet out of the cloud. Emerging from the lower cloud at 2,300 feet, they saw, what Green would have foretold, an upper stratum of dark cloud above.

Then they made excursions up and down, trying high and low to verify these conditions, and pa.s.sing through fogs both wet and dry, at last drifting earthward, through squalls of wind and rain with drops as large as fourpenny pieces, to find that on the ground heavy wet had been ceaselessly falling.

A day trip over the eastern suburbs of London in the same year seems greatly to have impressed Mr. Glaisher. The noise of London streets as heard from above has much diminished during the last fifteen years'

probably owing to the introduction of wood paving. But, forty years ago, Mr. Glaisher describes the deep sound of London as resembling the roar of the sea, when at a mile high; while at greater elevations it was heard at a murmuring noise. But the view must have been yet more striking than the hearing, for in one direction the white cliffs from Margate to Dover were visible, while Brighton and the sea beyond were sighted, and again all the coast line up to Yarmouth yet the atmosphere that day, one might have thought, should have been in turmoil, by reason of a conflict of aircurrents; for, within two miles of the earth, the wind was from the east; between two and three miles high it was exactly opposite, being from the west; but at three miles it was N.E.; while, higher, it was again directly opposite, or S.W.

During his researches so far Mr. Glaisher had found much that was anomalous in the way of the winds, and in other elements of weather. He was destined to find much more. It had been commonly accepted that the temperature of the air decreases at the average rate of 10 degrees for every 300 feet of elevation, and various computations, as, for example, those which relate to the co-efficient of refraction, have been founded on this basis; but Mr. Glaisher soon established that the above generalisation had to be much modified. The following, gathered from his notes is a typical example of such surprises as the aeronaut with due instrumental equipment may not unfrequently meet with.

It was the 12th of January, 1864, with an air-current on the ground from the S.E., of temperature 41 degrees,, which very slowly decreased up to 1,600 feet when a warm S.W. current was met with, and at 3,000 feet the temperature was 3 1/2 degrees higher than on the earth. Above the S.W.

stream the air became dry, and here the temperature decreased reasonably and consistently with alt.i.tude; while fine snow was found falling out of this upper s.p.a.ce into the warmer stream below. Mr. Glaisher discusses the peculiarity and formation of this stream in terms which will repay consideration.

"The meeting with this S.W. current is of the highest importance, for it goes far to explain why England possesses a winter temperature so much higher than is due to her northern lat.i.tude. Our high winter temperature has. .h.i.therto been mostly referred to the influence of the Gulf Stream.

Without doubting the influence of this natural agent, it is necessary to add the effect of a parallel atmospheric current to the oceanic current coming from the same region--a true aerial Gulf Stream. This great energetic current meets with no obstruction in coming to us, or to Norway, but pa.s.ses over the level Atlantic without interruption from mountains. It cannot, however, reach France without crossing Spain and the lofty range of the Pyrenees, and the effect of these cold mountains in reducing its temperature is so great that the former country derives but little warmth from it."

An ascent from Woolwich, arranged as near the equinox of that year as could be managed, supplied some further remarkable results. The temperature, which was 45 degrees to begin with, at 4.7 p.m., crept down fairly steadily till 4,000 feet alt.i.tude was registered, when, in a region of warm fog, it commenced rising abruptly, and at 7,500 feet, in blue sky, stood at the same reading as when the balloon had risen only 1,500 feet. Then, amid many anomalous vicissitudes, the most curious, perhaps, was that recorded late in the afternoon, when, at 10,000 feet, the air was actually warmer than when the ascent began.

That the temperature of the upper air commonly commences to rise after nightfall as the warmth radiated through day hours off the earth collects aloft, is a fact well known to the balloonist, and Mr. Glaisher carried out with considerable success a well-arranged programme for investigating the facts of the case. Starting from Windsor on an afternoon of late May, he so arranged matters that his departure from earth took place about an hour and three quarters before sunset, his intention being to rise to a definite height, and with as uniform a speed as possible to time his descent so as to reach earth at the moment of sundown; and then to re-ascend and descend again m a precisely similar manner during an hour and three-quarters after sunset, taking observations all the way. Ascending for the first flight, he left a temperature of 58 degrees on the earth, and found it 55 degrees at 1,200 feet, then 43 degrees at 3,600 feet, and 29 1/2 degrees at the culminating point of 6,200 feet. Then, during the descent, the temperature increased, though not uniformly, till he was nearly brushing the tops of the trees, where it was some 3 degrees colder than at starting.

It was now that the balloon, showing a little waywardness, slightly upset a portion of the experiment, for, instead of getting to the neighbourhood of earth just at the moment of sunset, the travellers found themselves at that epoch 600 feet above the ground, and over the ridge of a hill, on pa.s.sing which the balloon became sucked down with a down draught, necessitating a liberal discharge of sand to prevent contact with the ground. This circ.u.mstance, slight in itself, caused the lowest point of the descent to be reached some minutes late, and, still more unfortunate, occasioned the ascent which immediately followed to be a rapid one, too rapid, doubtless, to give the registering instruments a fair chance; but one princ.i.p.al record aimed at was obtained at least with sufficient truth, namely, that at the culminating point, which again was 6,200 feet, the temperature read 35 degrees, or about 6 degrees warmer than when the balloon was at the same alt.i.tude a little more than an hour before. This comparatively warm temperature was practically maintained for a considerable portion of the descent.

We may summarise the princ.i.p.al of Mr. Glaisher's generalisations thus, using as nearly as possible his own words:--

"The decrease of temperature, with increase of elevation, has a diurnal range, and depends upon the hour of the day, the changes being the greatest at mid-day and the early part of the afternoon, and decreasing to about sunset, when, with a clear sky, there is little or no change of temperature for several hundred feet from the earth; whilst, with a cloudy sky, the change decreases from the mid-day hours at a less rapid rate to about sunset, when the decrease is nearly uniform and at the rate of 1 degree in 2,000 feet.

"Air currents differing in direction are almost always to be met with.

The thicknesses of these were found to vary greatly. The direction of the wind on the earth was sometimes that of the whole ma.s.s of air up to 20,000 feet nearly, whilst at other times the direction changed within 500 feet of the earth Sometimes directly opposite currents were met with."

With regard to the velocity of upper currents, as shown by the travel of balloons, when the distances between the places of ascent and descent are measured, it was always found that these distances were very much greater than the horizontal movement of the air, as measured by anemometers near the ground.

CHAPTER XVI. SOME FAMOUS FRENCH AERONAUTS.

By this period a revival of aeronautics in the land of its birth had fairly set in. Since the last ascents of Gay Lussac, in 1804, already recorded, there had been a lull in ballooning enterprise in France, and no serious scientific expeditions are recorded until the year 1850, when MM. Baral and Bixio undertook some investigations respecting the upper air, which were to deal with its laws of temperature and humidity, with the proportion of carbonic acid present in it, with solar heat at different alt.i.tudes, with radiation and the polarisation of light, and certain other interesting enquiries.

The first ascent, made in June from the Paris Observatory, though a lofty one, was attended with so much danger and confusion as to be barren of results. The departure, owing to stormy weather, was hurried and illordered, so that the velocity in rising was excessive, the net constricted the rapidly-swelling globe, and the volumes of out-rushing gas half-suffocated the voyagers. Then a large rent occurred, which caused an alarmingly rapid fall, and the two philosophers were reduced to the necessity of flinging away all they possessed, their instruments only excepted. The landing, in a vineyard, was happily not attended with disaster, and within a month the same two colleagues attempted a second aerial excursion, again in wet weather.

It would seem as if on this occasion, as on the former one, there was some lack of due management, for the car, suspended at a long distance from the balloon proper, acquired violent oscillations on leaving the ground, and dashing first against a tree, and then against a mast, broke some of the instruments. A little later there occurred a repet.i.tion on a minor scale of the aeronauts' previous mishap, for a rent appeared in the silk, though, luckily, so low down in the balloon as to be of small consequence, and eventually an alt.i.tude of some 19,000 feet was attained. At one time needles of ice were encountered settling abundantly with a crackling sound upon their notebooks. But the most remarkable observation made during this voyage related to an extraordinary fall of temperature which, as recorded, is without parallel. It took place in a cloud ma.s.s, 15,000 feet thick, and amounted to a drop of from 15 degrees to -39 degrees.

In 1867 M. C. Flammarion made a few balloon ascents, ostensibly for scientific research. His account of these, translated by Dr. T. L.

Phipson, is edited by Mr. Glaisher, and many of the experiences he relates will be found to contrast with those of others. His physical symptoms alone were remarkable, for on one occasion, at an alt.i.tude of apparently little over 10,000 feet, he became unwell being affected with a sensation of drowsiness, palpitation, shortness of breath, and singing in the ears, which, after landing gave place to a "fit of incessant gaping" while he states that in later voyages, at but slightly greater alt.i.tudes, his throat and lungs became affected, and he was troubled with presence of blood upon the lips. This draws forth a footnote from Mr. Glaisher, which should be commended to all would-be sky voyagers.

It runs thus:--"I have never experienced any of these effects till I had long pa.s.sed the heights reached by M. Flammarion, and at no elevation was there the presence of blood." However, M. Flammarion adduces, at least, one rea.s.suring fact, which will be read with interest. Once, having, against the entreaties of his friends, ascended with an attack of influenza upon him, he came down to earth again an hour or two afterwards with this troublesome complaint completely cured.

It would seem as if the soil of France supplied the aeronaut with certain phenomena not known in England, one of these apparently being the occasional presence of b.u.t.terflies hovering round the car when at considerable heights. M. Flammarion mentions more than one occasion when he thus saw them, and found them to be without sense of alarm at the balloon or its pa.s.sengers. Again, the French observer seems seldom to have detected those opposite airstreams which English balloonists may frequently observe, and have such cause to be wary of. His words, as translated, are:--"It appears to me that two or more currents, flowing in different directions, are very rarely met with as we rise in the air, and when two layers of cloud appear to travel in opposite directions the effect is generally caused by the motion of one layer being more rapid than the other, when the latter appears to be moving in a contrary direction." In continuation of these experiences, he speaks of an occasion when, speeding through the air at the rate of an ordinary express train, he was drawn towards a tempest by a species of attraction.

The French aeronaut's estimate of what const.i.tutes a terrific rate of fall differs somewhat from that of others whose testimony we have been recording. In one descent, falling (without reaching earth, however) a distance of 2,130 feet in two minutes, he describes the earth rising up with frightful rapidity, though, as will be observed, this is not nearly half the speed at which either Mr. Glaisher or Albert Smith and his companions were precipitated on to bare ground. Very many cases which we have cited go to show that the knowledge of the great elasticity of a well-made wicker car may rob a fall otherwise alarming of its terrors, while the practical certainty that a balloon descending headlong will form itself into a natural parachute, if properly managed, reduces enormously the risk attending any mere impact with earth. It will be allowed by all experienced aeronauts that far worse chances lie in some awkward alighting ground, or in the dragging against dangerous obstacles after the balloon has fallen.

Many of M. Flammarion's experiments are remarkable for their simplicity.

Indeed, in some cases he would seem to have applied himself to making trials the result of which could not have been seriously questioned.

The following, quoting from Dr. Phipson's translation, will serve as an example:--

"Another mechanical experiment was made in the evening, and renewed next day. I wished to verify Galileo's principle of the independence of simultaneous motions. According to this principle, a body which is allowed to fall from another body in motion partic.i.p.ates in the motion of the latter; thus, if we drop a marble from the masthead of a ship, it preserves during its fall the rate of motion of the vessel, and falls at the foot of the mast as if the ship were still. Now, if a body falls from a balloon, does it also follow the motion of the latter, or does it fall directly to the earth in a line which is perpendicular to the point at which we let it fall? In the first case its fall would be described by an oblique line. The latter was found to be the fact, as we proved by letting a bottle fall. During its descent it partakes of the balloon's motion, and until it reaches the earth is always seen perpendicularly below the car."

An interesting phenomenon, relating to the formation of fog was witnessed by M. Flammarion in one of his voyages. He was flying low with a fast wind, and while traversing a forest he noticed here and there patches of light clouds, which, remaining motionless in defiance of the strong wind, continued to hang above the summits of the trees.

The explanation of this can hardly be doubtful, being a.n.a.logous to the formation of a night-cap on a mountain peak where warm moist air-currents become chilled against the cold rock surface, forming, momentarily, a patch of cloud which, though constantly being blown away, is as constantly re-formed, and thus is made to appear as if stationary.

The above instructive phenomenon could hardly have been noticed save by an aeronaut, and the same may be said of the following. Pa.s.sing in a clear sky over the spot where the Marne flows into the Seine, M.

Flammarion notes that the water of the Marne, which, as he says, is as yellow now as it was in the time of Julius Caesar, does not mix with the green water of the Seine, which flows to the left of the current, nor with the blue water of the ca.n.a.l, which flows to the right. Thus, a yellow river was seen flowing between two distinct brooks, green and blue respectively.

Here was optical evidence of the way in which streams of water which actually unite may continue to maintain independent courses. We have seen that the same is true of streams of air, and, where these traverse one another in a copious and complex manner, we find, as will be shown, conditions produced that cause a great deadening of sound; thus, great differences in the travel of sound in the silent upper air can be noticed on different days, and, indeed, in different periods of the same aerial voyage. M. Flammarion bears undeniable testimony to the manner in which the equable condition of the atmosphere attending fog enhances, to the aeronaut, the hearing of sounds from below. But when he gives definite heights as the range limits of definite sounds it must be understood that these ranges will be found to vary greatly according to circ.u.mstances. Thus, where it is stated that a man's voice may make itself heard at 3,255 feet, it might be added that sometimes it cannot be heard at a considerably less alt.i.tude; and, again, the statement that the whistle of a locomotive rises to near 10,000 feet, and the noise of a railway train to 8,200 feet, should be qualified an additional note to the effect that both may be occasionally heard at distances vastly greater. But perhaps the most curious observation of M. Flammarion respecting sounds aloft relates to that of echo. To his fancy, this had a vague depth, appearing also to rise from the horizon with a curious tone, as if it came from another world. To the writer, on the contrary, and to many fellow observers who have specially experimented with this test of sound, the echo has always appeared to come very much from the right place--the spot nearly immediately below--and if this suggested its coming from another world then the same would have to be said of all echoes generally.

About the same period when M. Flammarion was conducting his early ascents, MM. de Fonvielle and Tissandier embarked on experimental voyages, which deserve some particular notice. Interest in the new revival of the art of aeronautics was manifestly be coming reestablished in France, and though we find enthusiasts more than once bitterly complaining of the lack of financial a.s.sistance, still ballooning exhibitions, wherever accomplished, never failed to arouse popular appreciation. But enthusiasm was by no means the universal att.i.tude with which the world regarded aerial enterprise. A remarkable and instructive instance is given to the contrary by M. W. de Fonvielle himself.

He records an original ballooning exploit, organised at Algiers, which one might have supposed would have caused a great sensation, and to which he himself had called public attention in the local journals. The brothers Braguet were to make an ascent from the Mustapha Plain in a small fire balloon heated with burning straw, and this risky performance was successfully carried out by the enterprising aeronauts. But, to the onlooker, the most striking feature of the proceeding was the fact that while the Europeans present regarded the spectacle with curiosity and pleasure, the native Mussulmans did not appear to take the slightest interest in it; "And this," remarked de Fonvielle, "was not the first time that ignorant and fanatic people have been noted as manifesting complete indifference to balloon ascents. After the taking of Cairo, when General Buonaparte wished to produce an effect upon the inhabitants, he not only made them a speech, but supplemented it with the ascent of a fire balloon. The attempt was a complete failure, for the French alone looked up to the clouds to see what became of the balloon."

In the summer of 1867 an attempt was made to revive the long extinct Aeronautic Company of France, established by De Guyton. The undertaking was worked with considerable energy. Some forty or fifty active recruits were pressed into the service, a suitable captive balloon was obtained, thousands of spectators came to watch the evolutions; and many were found to pay the handsome fee of 100 francs for a short excursion in the air. For all this, the effort was entirely abortive, and the ballooning corps, as such, dropped out of existence.

A little while after this de Fonvielle, on a visit to England, had a most pathetic interview with the veteran Charles Green, who was living in comfortable retirement at Upper Holloway. The grand old man pointed to a well-filled portfolio in the corner of his room, in which, he said, were accounts of all his travels, that would require a lifetime to peruse and put in order. Green then took his visitor to the end of the narrow court, and, opening the door of an outhouse, showed him the old Na.s.sau balloon. "Here is my car," he said, touching it with a kind of solemn respect, "which, like its old pilot, now reposes quietly after a long and active career. Here is the guide rope which I imagined in former years, and which has been found very useful to aeronauts.... Now my life has past and my time has gone by.... Though my hair is white and my body too weak to help you, I can still give you my advice, and you have my hearty wishes for your future."

It was but shortly after this, on March 26, 1870, that Charles Green pa.s.sed away in the 85th year of his age.

De Fonvielle's colleague, M. Gaston Tissandier, was on one occasion accidentally brought to visit the resting place of the earliest among aeronauts, whose tragic death occurred while Charles Green himself was yet a boy. In a stormy and hazardous descent Tissandier, under the guidance of M. Duruof, landed with difficulty on the sea coast of France, when one of the first to render help was a lightkeeper of the Griz-nez lighthouse, who gave the information that on the other side of the hills, a few hundred yards from the spot where they had landed, was the tomb of Pilatre de Rozier, whose tragical death has been recorded in an early chapter. A visit to the actual locality the next day revealed the fact that a humble stone still marked the spot.