On the theory of the Variations of Atmospherical Phcenomena. 295 



The establishment of meteorological stations in distant parts 

 of the globe had, generally speaking, for its immediate object, so 

 to complete the partial knowledge we already possessed of the 

 phsenomena over a considerable portion of its surface, as to 

 enable us to take a general view of their course over the whole 

 globe ; the result of those endeavours has even exceeded what 

 was hoped for, as besides the information obtained respecting 

 regions where our knowledge was most defective, fresh light has 

 been thrown on those with which we had supposed ourselves 

 already completely acquainted. 



Meteorology commenced with us by the study of European 

 phsenomena, and its next principal extension was to phsenomena 

 observed in the tropical parts of America. If what is true of 

 Europe were equally true of the temperate and cold zones of the 

 earth in all longitudes, and if tropical America in like manner 

 afforded a perfect example of the tropical zone generally, it would 

 be of little consequence where the science of meteorology had 

 been first cultivated ; but this is not the case, and a too hasty 

 generalization has led to the neglect of important problems, 

 while others less important have been regarded as essential and 

 placed in the foremost rank. It was necessary that the science 

 should be freed from these youthful trammels, and this needful 

 enfranchisement has been effected by the Russian and by the 

 English system of observations. Russia has done her part in 

 freeing the meteorology of the temperate and cold zones from 

 impressions derived exclusively from the limited European type ; 

 and England, which by its Indian stations had undertaken for 

 the torrid zone the same task of enlarging and rectifying the 

 views previously entertained, has besides, by its African and 

 Australian stations (Cape of Good Hope and Hofearton), opened 

 to us the southern hemisphere, and first rendered it possible to 

 treat of the atmosphere as a whole. I will now endeavour to 

 show the importance of being enabled to take such general views, 

 selecting as an example the annual variation of the barometer. 



The study of the annual barometric variation had long been 

 singularly neglected, while the diurnal barometric variation had 

 had devoted to it an attention quite disproportioned to its subor- 

 dinate interest in reference to the general movements of the 

 atmosphere. This otherwise incomprehensible mistake is excused 

 by the localities where nature had been first interrogated. As 

 the diurnal variation had manifested itself with great distinctness 

 and regularity in tropical America, it naturally presented itself 

 as an object of interest in Europe also. The annual variation, 

 on the other hand, is inconsiderable, both in Europe and the 

 tropical parts of America ; and thus, while atmospheric phseno- 

 mena were treated simply as facts of which the periodicity alone 



