SECT. XXVIII. PHOSPHORESCENCE. 295 



light at pleasure, no doubt to enable them to pursue their prey 

 at depths where the sunbeams cannot penetrate. Flashes of light 

 are frequently seen to dart along a shoal of herrings or pilchards ; 

 and the Medusa tribes are noted for their phosphorescent bril- 

 liancy, many of which are extremely small, and so numerous as 

 to make the wake of a vessel look like a stream of silver. 

 Nevertheless, the luminous appearance which is frequently ob- 

 served in the sea during the summer months cannot always be 

 attributed to marine animalcule, as the following narrative will 

 show : 



Captain Bonnycastle, coming up the Gulf of St. Lawrence 

 on the 7th of September, 1826, was roused by the mate of the 

 vessel in great alarm from an unusual appearance. It was 

 a starlight night, when suddenly the sky became overcast in 

 the direction of the high land, and an instantaneous and in- 

 tensely vivid light, resembling the aurora, shot out of the 

 hitherto gloomy and dark sea on the lee bow, which was so bril- 

 liant that it lighted everything distinctly even to the mast-head. 

 The light spread over the whole sea between the two shores, and 

 the waves, which before had been tranquil, now began to be agi- 

 tated. Captain Bonnycastle describes the scene as that of a 

 blazing sheet of awful and most brilliant light. A long and 

 vivid line of light, superior in brightness to the parts of the sea 

 not immediately near the vessel, showed the base of the high, 

 frowning, and dark land abreast ; the sky became lowering and 

 more intensely obscure. Long tortuous lines of light showed 

 immense numbers of very large fish darting about as if in con- 

 sternation. The sprit-sail yard and mizen-boom were lighted 

 by the glare, as if gaslights had been burning directly below 

 them ; and until just before daybreak, at four o'clock, the most 

 minute objects were distinctly visible. Day broke very slowly, 

 and the sun rose of a fiery and threatening aspect. Eain fol- 

 lowed. Captain Bonnycastle caused a bucket of this fiery water 

 to be drawn up ; it was one mass of light when stirred by the 

 hand, and not in sparks as usual, but in actual coruscations. A 

 portion of the water preserved its luminosity for seven nights. 

 On the third night, the scintillations of the sea reappeared ; the 

 sun went down very singularly, exhibiting in its descent a 

 double sun ; and, when only a few degrees high, its spherical 

 figure changed into that of a long cylinder, which reached the 



