( 80 ) 



of (he wind, and finally pUmned an exjjeiiition with a [)ur[)ose of 

 trying by experiment with kites on board a steamship to make 

 snre abont the movement of the air above the regions of the 

 trade- winds. 



Anotlier investigator, worlving nnder similar conditions with no 

 less skill and snccess, is L. Teissekenx' de Bort, the founder and 

 proprietor of the "Observatoire de Météorologie Dynamiqne" at 

 Trappes. Having been already for a long time organising ascents 

 for meteorological pnrj^oses this excellent investigator in later years 

 started his "ballons-sonde" in F'rance and in foreign countries in 

 large numbers, to record temperature and moisture of the atmosphere 

 at a height of 10 to 15 kilometers. In the meanwhile he was inde- 

 fatigably working at the improvement of the recording-apparatus.* 

 Now, for nearly a year, he is — supported by the Swedish and 

 Danish Governments — very successfully engaged in a systematic 

 examination, by means of kites and balloons, of the atmosphere 

 above Jutland and the Danish Isles. 



On the other side much respect and admiration are due to the 

 perseverance and talent, with which H. H. Hildebrandsson since 

 1873 has been trying by means of a large system of stations to make 

 simultaneous observations of clouds and to <ji^et from these the knowledge 

 of the movements of the upper air, necessary for a development of 

 the theory of general circulation. He began Avith observations in 

 Sweden, but knew by i)ointing to first results of obvious importance 

 how to rouse gradually interest for the labour with the meteorolo- 

 gists of nearly all nations, especially with the "International Meteoro- 

 logical Committee." This led to the nomination of an international 

 committee for (he ol)ser\ation of clouds and in consequence to the 

 publication of an international cloud-atlas, in which it was principally 

 his nomenclature of the different forms of clouds that was adopted 

 and elucidated by plain illustrations. Finally it led also to the 

 issuing of simultaneous observations all over the civilised world 

 during a whole year, the "cloud-year" 1896/'97. 



Very important are the results which have been derived by 

 Hildebrandsson from the materials gathered. Some current ideas 

 about the movements of the upper air seem to be entirely subverted. 

 They have shown e. g. that in the (northern) temperate zone both 

 the u])per and the lower air on an average perform a whirling 

 movement in the sense of the earth's rotation, round the pole as a 

 centre, but with a centripetal component in the lower, a centrifugal 

 component iji the higher layers, a movement, therefore quite different, 

 from the southwestern lower current and the northwestern higher 



