290 American Scientific Association. 



poles, but that could not be true; on account of the convergence 

 of the meridians, there was not room for the air at the 

 poles. There were middle systems, of intermediate currents of air. 

 But these points were not fully established, There were excep- 

 tions in the general action which could be determined in their 

 general bearings only by long observation. 



One cause of the fitful disturbances of the atmosphere was 

 the conversion of water into vapor. During a single shower an 

 amount of water fell upon the Smithsonian Institute building equal 

 to 2<>,000 horse-power an hour; that is to say the heat necessary to 

 evaporate it would be equal to that required for working an engine of 

 twenty thousand horse-power one hour. Another cause of disturbance 

 was the motion of the earth itself upon its axis. In illustration, 

 diagrams were given showing that the currents of air moved in 

 circles, — that the same quantity of air that moved north must come 

 from the north, of course not in the same track. Observations 

 made tended to show a series of currents completely around the 

 earth, north and south of the equator, also in the temperate lati- 

 tudes, and in the Arctic circles. The calms at the equator, it was 

 shown, was caused by the upward currents of the air, — currents 

 coming from the north and south and rising over the equator, under 

 the influence of heat. 



In regard to the meteorology of our own continent, it was shown 

 that there were four circles, — two in the Atlantic, one of which the 

 G-ulf Stream complete its circle once in three years, one in the South- 

 ern Atlantic, one in the Northern Pacific, and one in the Southern 

 Pacific. These are sub-divided into minor currents. It is found 

 that the cold Arctic current setting south from the coast of Labra' 

 dor, passes through the G-ulf of St. Lawrence, while the ice which 

 comes down sets eastward towards Europe. Between these there 

 is produced the deposition of vapor or fog on the banks of New 

 foundland. 



He had been assured by Mr. Wise, the aeronaut, that out of 

 200 ascensions, he had always been enabled to move east on 

 reaching an upper stratum of air. He (Prof. H.) therefore did not 

 think it impossible that an aerial voyage could be made to Europe. 

 Success would greatly depend upon the ability to make the balloon 

 air-tight. If kept in the upper strata, it might succeed^ 

 although it was not certain there was not a reverse current in mid 

 ocean. In the lower strata there were irregularities which must 

 be avoided.. The balloon he considered as an important means of 



