182 M. de Quatrefages on the Phosphorescence of 



Never, in the regions of which I speak, have I seen the waves 

 breaking on a shore presenting the appearance described by 

 ti'avellers. 



B. The second kind of phosphorescence I saw for the first time 

 near StromboU. Here the effects of the hght were heightened 

 by the dark hue of the waves around the volcanic cone ; more- 

 over, at Boulogne, and probably at Havre, Dieppe, Ostend, &c., 

 this phsenomenon is as complete and interesting as at Stromboli. 



At Boulogne, the phosphorescence is apparent throughout the 

 harbour, except where the waters of the Liane flow into it. It is 

 diminished and perhaps destroyed towards the entrance, between 

 the two dykes. It is very decided through the whole port pro- 

 perly so called, in the basin, and especially in the little cove 

 named the "Pare aux huitres." The last locality, being very 

 accessible, afforded opportunity for studying all the details of 

 the phsenomenon. 



However favourable the circumstances for observation, the 

 water when quiet was always perfectly dark ; but the least move- 

 ment drew forth light. A grain of sand cast upon the dark sur- 

 face produced a luminous spot, and the undulations of the water 

 were so many bright circles. A stone as large as the fist pro- 

 duced the same results in a more intense degree, and moi-eover 

 each splashing occasioned a scintillation like that of a bar of 

 iron at a white heat when struck upon an anvil. The entrance 

 of a steamboat when the phsenomenon was most apparent, was 

 a magnificent sight, and recalled to mind the descriptions of 

 travellers. 



The " Pare aux huitres " was always bordered by a phospho- 

 rescent girdle, resulting from the incessant undulations of the sea, 

 which reached the shore under the form of small waves ; but in 

 perfectly fair weather this light was too feeble to be distinguished 

 at a distance. When these undulations were only 3 to 4 inches 

 high, the ring might easily be seen from the pier, throughout 

 its whole extent, and was especially marked in the inner part of 

 this little harbour. 



At Boulogne, as at Stromboli, these luminous waves, seen from 

 a distance, presented a uniform tint of a pale dull white. It might 

 be called almost a froth, resulting from the action of the waves 

 against the shore ; and seen at mid-day under the most favour- 

 able circumstances, that was all I could distinguish at a distance 

 of seventy to eighty yards. In proportion as you advance the 

 appearance changes ; the waves, as they near the shore, seem 

 crowned with a light bluish flame, which M. Becquerel has 

 justly compared to that of a bowl of punch. When they strike, 

 this brightness becomes whiter and more vivid. On reaching 

 the bank, you often see these same waves under the aspect of 



