228 NINTH ANNUAL REPORT OF 



CO operate, and thus an ascensional power be generated sufficient to 

 make it rise to the region of the clouds, where rarefaction so increases 

 the calorific capacity of the air, that it robs the aqueous vapor, exist- 

 ing in the air, of its heat, and thus condenses it into a cloud. Mean- 

 while the heat involved by the vapor m condensing keeps the tempera- 

 ture higher than if the moisture were not present, and, according to 

 Espy, should be productive of an upward force competent to produce a 

 tornado. But according to Wise's statements, the uprising current 

 does not reach the upper stratum of clouds. 



19. In the fifth paragraph of his synopsis it is alleged not to be con- 

 tinued higher than the lower cloud ; but in his narrative he alleges that 

 when " the balloon was half way down between the cloud and the 

 lower stratum, the uprising current arrested the descent." and was 

 rising and whirhng as he was in the margin of the storm. 



20. The fact that the balloon, instead of being carried ahead b}' the 

 current in which the " thunder gust," first noticed by our voyager, 

 floated, was carried towards it so as to be " involved in the outskirts of 

 its rain," and to be affected by its motion, can only be ascribed to cen- 

 tripetal currents ; and the whirl might be the natural consequence of 

 the conflicting concurrence of such currents. The rising of the air in 

 the axis of the whirl would require that there should be inblowing cur- 

 rents to supply the deficit created by this upward blast. It is difficult 

 to comprehend why the balloon was not drawn into the vortex and car- 

 ried round with it. 



21. I have never seen nor lieard an}^ evidence justifs'ing the idea 

 that an ordinary thunder gust involves the existence of a whirling mo- 

 tion about a vertical axis. The rushing together of two thunder gusts, 

 or clouds, to form a third, as stated in the narrative, and noticed in the 

 9th paragraph of the synopsis, indicates the existence of two currents 

 rushing towards an intermediate space, where a whirl might contin- 

 gently ensue, a result which is quite consistent with the inblowing theo- 

 ry, agreeably to which whirling is an incidental consequence, not a 

 cause nor an essential feature of storms. In these respects Wise's ob- 

 servations are irreconcilable with the rotatory theory, which assumes 

 the whole of the theatre of stormy reaction to whirl about a common 

 axis. Agreeabl}^ to this idea, the two thunder gusts, instead of rushing 

 towards each other, would have to be carried liirther apart by a cen- 

 trifugal motion, and the air, instead of rising about the axis, would 

 have been drawn downward to supply the centrifugal* currents. 



22. The persistence of the upper stratum, or ," cloud cap," as this 

 stratum is designated in the narrative, is inconsistent with the Espyan 

 hypothesis, which requires that in ever}^ thunder gust, no less tlian in a 

 tornado, that the whole mass of air, of which the commotions consti- 

 tute the storm, should be turned inside out, by an upward blast pro- 

 duced by the heat arising from condensing vapor. Of course, this 

 force could not come into existence below the level at which the con- 

 densation commences, in other words, that of the lower stratum of 

 clouds, and could not continue to operate further than the inferior level 

 of the upper stratum. Any buoyancy tlius created would tend to carry 

 ap the "cloud cap," while it could have no effect at any level below 



