297 



aware. This wave was composed of seven oscillations, three 

 at each side of the central one ; and the barometric curve pre- 

 sented a very symmetrical character. It culminated on March 

 9th, when at 9 a. m. the barometer attained the height of 

 30-751 inches. The wind was easterly during the whole 

 transit, but varied very irregularly between SE. and NE. 



The barometric curve of March, 1847, is remarkable for 

 its regularity, and its near approach to symmetry. The 

 wave commenced its passage over Dublin Feb. 18, cul- 

 minated March 2, and passed off March 15, its transit oc- 

 cupying twenty-five days. The highest pressure (March 

 2, 7 p. M.) was 30-692 inches. The central portion of the 

 curve presenting a great regularity of form, and predomina- 

 ting greatly over the minor oscillations, this wave seems ad- 

 mirably suited to the examination of the relation between the 

 molecular movement of the air and the pressure. The principal 

 features of the phenomenon were a steady wind from SE. (Feb. 

 22-26), preceding the rise of the principal oscillation. This 

 was followed (Feb. 28-March 6) by a steady vvind from N E. 

 during its transit, and (March 7-8) by a NVV. wind after 

 its passage. The oscillation is also remarkable for a retro- 

 grade movement of the wind through nearly the whole com- 

 pass. The wave commenced and ended with a gale ; the 

 intensity of the wind increased also before and after the prin- 

 cipal oscillation. 



The writer concluded by some remarks upon the bearing 

 of the facts noticed upon the theory of wave-propagation. 



The following notice on the manufacture of sulphuric acid, 

 by Professor Edmund Davy, was communicated by Professor 

 Graves. 



" My attention has been for some time directed to the con- 

 sideration and examination of the different circumstances under 

 which sulphuric acid may be formed ; as by the use of the ni- 

 trates of potash or soda, and nitric acid or nitrous acid gas, 



