224 



side, the visible effect is a drying up and clearing of the air, with a 

 rising barometer and falling thermometer ; while on the equatorial 

 side, overpowering quantities of warm moist air rushing from 

 comparatively inexhaustible tropical supplies push towards the 

 north-east as long as their impetus lasts (however originated), and 

 are successively chilled, dried, and intermingled with the always 

 resisting, though at first recoiling, polar current. After such 

 struggles these two currents unite in a varying intermediate state 

 and direction, one or other prevailing gradually. 



Very plain and practical conclusions are deducible from these 

 considerations : 



One, and the most important, is that in a gale which seems likely 

 to be near the central part of a storm, that should be (of course) 

 avoided by a ship which has sea room : a seaman, facing the 

 wind, knows that the centre is on his right hand in the northern 

 hemisphere, on his left in the southern ; he therefore is informed 

 how to steer. 



Another valuable result is that telegraphic communication can 

 give notice of a storm's approach, to places then some hundred miles 

 distant, and not otherwise forewarned. 



The Society adjourned to January 12, 1860. 



January 12, 1860. 

 Sir BENJAMIN C. BRODIE, Bart., President, in the Chair. 



The Right Hon. Edward Lord Stanley was admitted into the 

 Society. 



The following communications were read : 

 I. "Notes of Researches on the Poly- Ammonias." No. VII. 

 On the Diatomic Ammonias. By A. W. HOFMANN, LL.D., 

 F.R.S. Received December 14, 1859. 



In continuing my inquiries into the nature of the organic bases, 

 I was led in the commencement of the year 1858 to repeat some 

 experiments on the action of dibromide of ethylene upon ammonia, 



