75 



shock ? This is a question of difficult solution. 

 Is it a slight augmentation of temperature which 

 favours the phosphorescence? or does the light re- 

 turn, because the surface is renewed, by putting 

 the animal parts proper to disengage the phos- 

 phoric hydrogen in contact with the oxygen of 

 the atmospheric air ? I have proved by experi- 

 ments published in 1797, that the shining of 

 wood is extinguished in hydrogen gas, and in 

 pure azotic gas, and that it's light reappears 

 whenever we mix with it the smallest bubble of 

 oxygen gas. These facts, to which we shall here- 

 after add several others, lead to the discovery of 

 the causes of the phosphorescence of the sea, 

 and of that peculiar influence, which the shock 

 of the waves exercises on the production of 

 light. 



When we were between the Isle of Madeira 

 and the coasts of Africa, we had slight breezes 

 and dead calms, very favourable for the magnetic 

 observations, which occupied me during this pas- 

 sage. We were never wearied of admiring the 

 beauty of the nights ; nothing can be compared 

 to the transparency and serenity of an African 

 sky. We were struck with the innumerable 

 quantity of falling stars, which appeared at 

 every instant. The farther progress we made 

 toward the south, the more frequent was this 

 phenomenon, especially near the Canaries. I 

 have observed during my excursions, that these 



