146 ROCHESTER ACADEMY OF SCIENCE. [May 9, 



ing altitudes. There appears to be a dip downward of a stratum of 

 very cold air instead of the projection upward of warm air. The 

 limits of this cold are sharply defined and do not shade off gradually 

 as would be the case if it were cooling due to the expansion of a 

 rising column of air from which the pressure is being moved. In the 

 case of thunderstorms which have been held to be typical examples 

 of the indraught and uprush idea, the projection downward of cold air 

 is so extreme that it reaches the surface of the earth and presents so 

 sharp a margin that the temperature commonly falls fifteen or twenty 

 degrees in two or three minutes as the storm breaks and rises again 

 as it passes away. Moreover in such storms the wind at the surface 

 of the earth blows briskly outward in every direction as well as that 

 of the storm's advance, which is the very reverse of an indraught. 

 This has been noticed even when there has been little or no precipi- 

 tation, so that the projection downward cannot be due to entanglement 

 with rain drops. Indeed the rain itself not unfrequently appears to 

 be upborne and whirled along by the gust, and it is precisely in those 

 storms where the downpour is heaviest that the lines of descent of 

 the rain drops are most nearly vertical and there is no gust at all. 

 In like manner in the case of a waterspout which came aboard of a 

 ship there was found to be snow at its center, so that here also there 

 must have been a very decided dipping downward of cold air. In 

 view of facts such as these it is difficult to see how the vertical com- 

 ponent of motion in cyclones can be heat. 



So likewise in the case of anti-cyclones the temperatures at 

 different altitudes do not account for the direction of movement. 

 The writer has made a list of instances in which the temperature on 

 Mt. Washington was higher than at surrounding stations at lower 

 levels, from which it appears that as a rule this happens during the 

 passage of centers of high barometer. Thus the out-flowing air cur- 

 rents from such centers are compelled to derive their supply from the 

 descent of masses of air relatively warmer than that at the surface 

 of the earth. Such air being warmer ought not to descend at all, or 

 if compelled to descend in virtue of the general circulation of the 

 atmosphere, it ought to be warmed in the process by virtue of increas- 

 ing compression by superincumbent air strata as it reaches lower levels. 

 But instead of becoming warmer it becomes colder. Thus in the case 

 of anti-cyclones also it is difficult to see how the vertical component 

 of motion can depend upon temperature. 



Again air leaving centers of high barometer or approaching cen- 

 ters of low barometer does not advance in a radial direction. 



