124 Contributions to Meteorology. 



Whence it appears that the island is deficient in the north- 

 ern families of the Saxifrages, Amentaceoz, Caryophyllea?, 

 in the first of these especially. It is poor likewise in the pre- 

 dominant families of the tropics, the Euphorbiacea:, Malvaceae 

 and Corymbifera?, which latter are only in the proportion of 

 1 to 19, but at the Cape 1 to 5, and in other countries of the 

 equator 1 to 6. But the Cichoracew, which belong to the 

 temperate zone, are here numerous. 



In our walks, we found upon the shore whole banks of 

 Fuci : but it is at the Cape we hope to meet with treasures in 

 this department. 



Dr H. Kuhl. 



Art. XXIV— CONTRIBUTIONS TO METEOROLOGY. 



1. On the Negative Electricity of Showers. By Mr John Foggo. 



Sudden and copious precipitations of moisture from the at- 

 mosphere, whether in form of rain or hail, are generally at- 

 tributed to the agency of electricity. Hail showers appear 

 to be always accompanied by indications of electricity, amount- 

 ing frequently to discharges of lightning with thunder. In 

 every fall of rain, indeed, electrical indications more or less 

 strong may be discovered ; but, in those extensive rains which 

 spread over vast tracts of country, the electrometer is seldom 

 affected to a greater degree than may be easily considered as 

 the spontaneous electricity of a moist atmosphere. But the 

 showers, in which the influence of this element appears more 

 decided, have characters different from general rains, and even 

 from the heavy showers which occur in boisterous weather. 

 They are more local, or circumscribed, of short duration, and 

 the precipitation is most violent at the commencement ; and 

 when they have been preceded by dry and cold weather, 

 their effects are discernible in the rapidity with which vegeta- 

 tion acquires a renewed freshness and vigour which cannot be 

 imparted by artificial watering, or an ordinary shower of 

 equal amount. They are also distinguished by the regulari- 

 ty with which the variations in the kind of electricity succeed 

 each other. When negative electricity occurs in broken wca- 





