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000 feet the temperature remains nearly constant； or even increases； the regular diminution being again resumed and generally maintained at a rate slightly less rapid than in the lower part of the atmosphere； and commencing from a higher temperature than would have existed but for the interruption noticed。〃 The analysis of the upper air showed the proportion of oxygen and nitrogen to vary scarcely more than at different spots on the earth。
As it is necessary at this point to take leave of the veteran Green as a practical aeronaut； we may here refer to one or two noteworthy facts and incidents relating to his eventful career。 In 1850 M。 Poitevin is said to have attracted 140；000 people to Paris to look at an exhibition of himself ascending in a balloon seated on horseback； after which Madame Poitevin ascended from Cremorne Gardens in the same manner； the exhibition being intended as a representation of 〃Europa on a Bull。〃 This； however； was discountenanced by the authorities and withdrawn。 The feats were； in reality； merely the repetitions of one that had been conceived and extremely well carried out by Green many years beforeas long ago； in fact； as 1828； when he arranged to make an ascent from the Eagle Tavern； City Road； seated on a pony。 To carry out his intention； he discarded the ordinary car； replacing it with a small platform； which was provided with places to receive the pony's feet； while straps attached to the hoop were passed under the animal's body； preventing it from lying down or from making any violent movement。 This the creature seemed in no way disposed to attempt； and when all had been successfully carried out and an easy descent effected at Beckenham； the pony was discovered eating a meal of beans with which it had been supplied。
Several interesting observations have been recorded by Green on different occasions； some of which are highly instructive from a practical or scientific point of view。 On an ascent from Vauxhall； in which he was accompanied by his friend Spencer and Mr。 Rush； he recorded how； as he constantly and somewhat rapidly rose； the wind changed its direction from N。W。 through N。 to N。E。； while he remained over the metropolis； the balloon all the while rotating on its axis。 This continual swinging or revolving of the balloon Green considers an accompaniment of either a rapid ascent or descent； but it may be questioned whether it is not merely a consequence of changing currents； or； sometimes； of an initial spin given inadvertently to the balloon at the moment of its being liberated。 The phenomenon of marked change which he describes in the upper currents is highly interesting； and tallies with what the writer has frequently experienced over London proper。 Such higher currents may be due to natural environment； and to conditions necessarily prevailing over so vast and varied a city； and they may be able to play an all…important part in the dispersal of London smoke or fog。 This point will be touched on later。 In this particular voyage Green records that as he was rising at the moment when his barometer reached 19 inches； the thermometer he carried registered 46 degrees； while on coming down； when the barometer again marked 19 inches； the same thermometer recorded only 22 degrees。 It will not fail to be recognised that there is doubtless here an example of the errors alluded to above； inseparable from readings taken in ascent and descent。
A calculation made by Green in his earlier years has a certain value。 By the time he had accomplished 200 ascents he was at pains to compute that he had travelled across country some 6；000 miles； which had been traversed in 240 hours。 From this it would follow that the mean rate of travel in aerial voyages will be about twenty…five miles per hour。 Towards the end of his career we find it stated by Lieutenant G。 Grover； R。E。； that 〃the Messrs。 Green； Father and Son； have made between them some 930 ascents； in none of which have they met with any material accident or failure。〃 This is wonderful testimony； indeed； and we may here add the fact that the father took up his own father； then at the age of eighty…three； in a balloon ascent of 1845； without any serious consequences。 But it is time that some account should be given of a particular occasion which at least provided the famous aeronaut with an adventure spiced with no small amount of risk。 It was on the 5th of July； 1850； that Green ascended； with Rush as his companion； from Vauxhall； at the somewhat late hour of 7。50 p。m。； using； as always； the great Nassau balloon。 The rate of rise must have been very considerable； and they presently record an altitude of no less than 20；000 feet； and a temperature of 12 degrees below freezing。 They were now above the clouds； where all view of earth was lost； and； not venturing to remain long in this situation； they commenced a rapid descent； and on emerging below found themselves sailing down Sea Reach in the direction of Nore Sands； when they observed a vessel。 Their chance of making land was； to say the least； uncertain； and Green； considering that his safety lay in bespeaking the vessel's assistance； opened the valve and brought the car down in the water some two miles north of Sheerness； the hour being 8。45； and only fifty…five minutes since the start。 The wind was blowing stiffly； and； catching the hollow of the half…inflated balloon； carried the voyagers rapidly down the river； too fast； indeed； to allow of the vessel's overtaking them。 This being soon apparent； Green cast out his anchor； and not without result； for it shortly became entangled in a sunken wreck； and the balloon was promptly 〃brought up；〃 though struggling and tossing in the broken water。 A neighbouring barge at once put off a boat to the rescue； and other boats were despatched by H。M。 cutter Fly； under Commander Gurling。 Green and Rush were speedily rescued； but the balloon itself was too restive and dangerous an object to approach with safety。 At Green's suggestion； therefore； a volley of musketry was fired into the silk' after which it became possible to pass a rope around it and expel the gas。 Green subsequently relates how it took a fortnight to restore the damage； consisting of sixty…two bullet rents and nineteen torn gores。
Green's name will always be famous； if only for the fact that it was he who first adopted the use of coal gas in his calling。 This； it will be remembered； was in 1821； and it should be borne in mind that at that time household gas had only recently been introduced。 In point of fact； it first lighted Pall Mall in 1805； and it was not used for the general lighting of London till 1814。
We are not surprised to find that the great aeronaut at one time turned his attention to the construction of models； and this with no inconsiderable success。 A model of his was exhibited in 1840 at the Polytechnic Institution； and is described in the Times as consisting of a miniature balloon of three feet diameter； inflated with coal gas。 It was acted on by fans； which were operated by mechanism placed in the car。 A series of three experiments was exhibited。 First； the balloon being weighted so as to remain poised in the still air of the building； t