V 



134 Natural History of the Ockan, ^C, 



1. Absorbed solar light. Wilson of Edinburgh madf* 

 many experiments to ascertain if this was true. He found 

 that water retained this property when it had been covered^ 

 with oil, or when drawn from a great depth. Surface water 

 exposed to the sun's rays retained it. The electronometer 

 did not affect it- 

 Many substances on land absorb light, and trav^ellers in 



warm cUmates are often benefitted by the emission of it. 



Gregg mentions a man who could read in the dark — and 

 another who could do the same after drinking wine. 



2. Marine animals. Dr. Forster, Oct. 29, 1772, off the 

 Cape of Good Hope, near the shore in a storm, observed 

 eTcry wave to present a luminous crest; and that there 

 was a phosphoric line on the sides of the ship where the 

 weaves broke. He also saw large luminous bodies moving 

 in the water, and found that they were fishes; and that 

 when near each other, the small ones swam from the largerv 

 On examining a bucket of water, the luminous particles sub- 

 sided ; but the same property was manifested on agitation. 

 These particles were animals, globular, gelatinoo's, brown- 

 ish, and transparent. On the coast of Malabar they are verf 

 Williaflf. There are several species of animals engaged in 

 this phenomenon : but chiefly two — the Medusa and Acfi- 

 nia* The former are microscopic, and abundant in tvarrtr 

 climates' — ^the latter occasionally exhibit a remarkably strong 

 phosphorescence. Sir Jos. Banks mentions a Crustacea 

 which emitted light equal in quantity and lustre to ttiat of 

 the glow worm, 



3. Electric lumu^ousness is seen in the wake of ships, 

 Ittcc stars and globoles : sometimes extending: dver a great 

 part of the ocean. In the Indian seas, it forebodes a change 

 of weather. 



4. Decayed animal and vegetable snbstances frequently 

 become phosphorescent; and produce on agitation, the 

 most brilliant I^f, It i^ useless to specify, where so ma- 

 ny possess this property.* 



* Sin«e fmifehin* tliis paper, F have s*;eB in the Edinburgh Philo?, Journal 

 a notice of a paper on the "Luminosity on the s*a," by Dr. MacCuHooh, 

 published in the Quarterly Joofnal of Science and Arts :— and of another 

 paper on the same subject by Dt. Murrav, in the 3d Vol. of the Trans, of 

 the Wemerian Society; which I believe have- not yet reached this coun- 

 try: — ^at least I ba\-e noihad ail onnftrtunitv of sppmo- thAm. 



