2 Remarks on tlie Lianinosity of the Sea, 



This extract refers to a passage across the Menai Strait, 

 between Garth Ferry and Bangor, in company with my friend 

 Wilson of Warrington, about eleven o'clock in the evening 

 of the 27th of July, 1830. The day had been very hot, the 

 night was dark for that season, and the sea perfectly smooth 

 and calm. I regretted that I had neither leisure nor oppor- 

 tunity to bring away some of the water for microscopical 

 examination : but we had no phial at hand, and were quite 

 exhausted with a long and difficult, though delightful, ramble 

 over the sea rocks between Red Wharf Bay and Penmon 

 Point, and thence to Beaumaris, along the loose sand and 

 shingles of the coast ; and were, besides, loaded with a rich 

 harvest of plants, which required all our time and atten- 

 tion. But, though not then a stranger to the phenomenon, its 

 singularly vivid appearance struck me forcibly ; and I was 

 quite convinced that the luminous matter floated, as it were, 

 upon the surface like a thin coat of oil, for it was dispersed 

 or repelled by the motion of a stick or the finger, and was 

 confined to the circumference of an irregular circle around 

 them. I can scarcely agree with Mr. Westwood that it is 

 rendered visible by mere contact with the atmosphere, since it 

 must always be in contact from its lying on the surface ; yet 

 we have abundant proof that it is only excited by disturb- 

 ance. It struck me strongly, at the time, that it was elicited 

 hy friction, to which, I see, others have attributed it ; yet it 

 must be as sensibly alive to that agent as the iodide of nitro- 

 gen, for it was produced when I leaned over the boat and blew 

 upon the water. 



It is a well known fact, that dead fishes and MoUusca ge- 

 nerate phosphorescence during the incipient stages of putre- 

 faction ; and chemical experiments have ascertained that it is 

 increased, if it be not in some way caused, by the immersion 

 of such substances in a solution of some neutral salt. In sea 

 water, therefore, it is probably produced by muriate of soda 

 [common salt] ; and may not its situation on the surface be 

 explained by its uniting with the oleaginous matter disen- 

 gaged from decomposing animal substances, which, in a qui- 

 escent state of the sea, would rise and float like a film ? I 

 throw this out as mere conjecture, but it may help the philo- 

 sophic enquirer to solve the problem. 



This luminous matter, however, which often marks the 

 wake of a vessel in the night, and crests the waves with a 

 splendour not their own, is certainly not the only kind of 

 phosphorescence which the ocean exhibits. During the mild 

 nights of summer and autumn, innumerable Medus<^ (the 

 glowworms of the deep) may often be seen spangling its dark 



