22 WRITINGS OF JOSEPH HENRY. [1855- 



temperature, and the great movements of the atmosphere 

 of the globe, comparatively few stations of observation, of 

 the first class, are required ; but these should be properlj' 

 distributed, well furnished with instruments, and supj^lied 

 with a sufficient corps of observers, to record at all periods 

 of the day the prominent fluctuations. Such stations how- 

 ever can only be established and supported by the co-opera- 

 tion of a number of governments. 



A general plan of this kind for observing the meteoro- 

 logical and magnetical changes more extensively than had 

 ever before been undertaken, was digested by the British 

 Association in 1838, in which the principal governments of 

 Europe were induced to take an active part; and had that of 

 the United States and those of South America joined in 

 the enterprise, a series of watch-towers of nature would have 

 been distributed over every part of the earth. The follow- 

 ing were the stations of the several observatories estab- 

 lished : Those of the English Government were at Green- 

 wich, Dublin, Toronto, St. Helena, Cape of Good Hope, Van 

 Dieman's Land, Madras, Simla, Singapore, and Aden. The 

 Encsian observatories were at Boulowa, Helsingfors, Peters- 

 burg, Sitka, Catherineburg, Kasan, Barnaoul, NicolaiefF, 

 Nertschinsk, Tiflis, and Pekin. Those of Austria were at 

 Prague and Milan. In the United^States, an observatory 

 was established at Girard College, under the direction of 

 Professor Bache. The French Government had one at Al- 

 giers ; the Prussian Government, one at Breslau ; the Bava- 

 rian Government, one at Munich; and the Belgian, one at 

 Brussels. There was one at Cairo, supported by the Pasha 

 of Egypt, and one in India, at Travandrum. 



These observatories were established to carry out a series 

 of observations at the same moment of absolute time, every 

 two hours, day and night, during three years, together with 

 observations once every month, continuing 24 hours, at in- 

 tervals of five minutes each. They were all furnished with 

 standard instruments, and followed instructions adopted by 

 the directors of the general system. Operations were com- 

 menced in 1839, and in a number of cases, were continued 



