第53章 CHAPTER XV. FURTHER SCIENTIFIC VOYAGES OF GLAISHER

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 assailed 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, passing 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 passed, 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 masses 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 masses still piling high overhead, the eager observer, bent on further quests, was for pursuing the voyage; but Mr. Coxwell 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 passed 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 quantity 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 space 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 passing 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.