130 CRITICAL NOTICES OP NEW PUBLICATIONS. 



With respect to the danger usually considered as liable to occur in 

 the exercise of Aerostation, much is not required, in Mr. M.'s estima- 

 tion, to prove the fallacy of such fears. Mr. Green's two hundred 

 and twenty-six ascents, undertaken at all periods of the year, without 

 one disappointment to the public, and without one solitary instance of 

 fatal consequences, or even of an accident having disagreeable results, 

 Mr. M. thinks, ought to be a sufficient proof of how little danger is 

 to be apprehended in the practice of Aerostation, when managed by 

 a skilful leader, with the aid of those improvements which Mr. 

 Green's experience originated and successfully applied. 



Mr. M. M. abstains from making observations on the state of the 

 aerostatic art, in respect of the power of guiding a balloon according 

 to a given direction ; the want of which is said by him to be generally 

 considered as the greatest obstacle to its farther progress, and adap- 

 tation to the ordinary purposes of human life. As, however, the dis- 

 cussion of this question would extend to a considerable length, and 

 as it formed no part of the project in pursuance of which the late aerial 

 expedition was undertaken, he reserves the subject for a future and 

 more elaborate investigation. 



Mr. Green's previous discoveries are held, by their historian, as 

 yielding in importance to that whereby he has succeeded in enabling 

 the aeronaut to maintain the power of his balloon undiminished during 

 the most protracted voyage he may be required to perform. Mr. 

 Monqk Mason describes this highly-appreciated discovery in the fol- 

 lowing terms : — 



" In order fully to comprehend the value of this discovery, it is necessary 

 that some idea should be had of the difficulties the late enterprize was in- 

 tended to obviate, and of the eifects they were calculated to jjroduce upon 

 the farther progress of Aerostation. When a balloon ascends to navigate 

 the atmosphere, independent of a loss of power occasioned by its own imper- 

 fections, an incessant waste of its resources in gas and ballast becomes the in- 

 evitable consequence of its situation. No sooner has it quitted the earth 

 than it is immediately subjected to the influence of a variety of circum- 

 stances tending to create a difference in its weight ; augmenting or diminish- 

 ing, as the case may be, the power by the means of which it is supported. 

 The deposition or evaporation of humidity to the extent, in proportion to its 

 size, of several hundred weight ; the alternate heating and cooling of its gas- 

 eous contents by the remotion or interposition of clouds between the object 

 itself and the influence of the solar rays, with a variety of other more secret, 

 though not less powerful agencies, all so combine to destroy the equilibrivuu 

 which it is the main object of the aeronaut to preserve, that scarcely a mo- 

 ment passess without some call for his interposition, either to check the 

 descent of the balloon by the rejection of ballast, or to control its ascent by 

 the proportionate discharge of gas ; a process by which the whole power of 

 the balloon, however great its dimensions, must in time be exhausted, and 

 sooner or later terminate its career by succumbing to the laws of terrestrial 

 gravitation. By the simple contrivance of a rope of the requisite magnitude 

 and extent trailing on the ground beneath, (and if over the sea, with a suffi- 

 cient quantity of liquid ballast contained in vessels floating on its surface), 

 have all these difficulties been overcome, and all the features of the art com- 

 pletely and effectually reversed. Harnessed to the earth or ocean by a pow- 

 er too great for lier to resist, it is in vain the balloon endeavours to change 



