398 EAMBLES OF A NATURALIST. [Ch. XXIH. 



extinguished by moonlight, even when the moon is young. 

 It was exhibited, only less marked, on the two following 

 eveniags, and on the third we left False Bay, a locality 

 which has been remarked as very frequently exhibiting this 

 beautiful phenomenon. 



On the 7th of July, in lat. 28°, on the coast of China, 

 only two days after the occurrence of this form of lumiuo- 

 sity as first described, a heavy sweU. coming in from the 

 south-west was met by a north-east wind, and the ship 

 . rolled tremendously. The sea was beautifully luminous, 

 every wave breaking with a pale light, which was visible 

 at a considerable distance, so that the whole sea was 

 streaked with light ; and again that peculiar phenomenon, 

 of the ship sailing in a luminous sheath, was visible (see 

 page 142). I mention this case, because it was one of the 

 most striking instances of general luminosity which had 

 come under my notice : it appeared to be compounded of 

 the. two forms I have already described. 



The third form of limainosity to be described, consists 

 of moon-shaped patches of steady white light, which I have 

 found to be a very common phenomenon under certain cir- 

 cumstances. Next to the occurrence of sparks, and always 

 accompanied by them, this form of luminosity is most fre- 

 quently seen, and does not appear to be confined to any 

 particular locality. I first observed it in the Mediterranean, 

 on the first night on which the absence of the moon allowed 

 it to be visible ; and I have since found it to be no less 

 frequent in the Red Sea, the Indian Ocean, the China Sea, 

 and the Atlantic north and south of the Equator. It is 

 most commonly visible in the wake of the ship, and consists 

 of numerous round patches of light, closely resembling the 

 appearance of white-hot shot, of various sizes, beneath the 



