NATURAL HISTORY. 



G37 



Captain Horsburgh, in the notes 

 he gave to Sir Joseph Banks, says, 

 there is a peculiar phaenomenon 

 sometimes seen within a few de- 

 grees distance of the coast of Ma- 

 labar, during the rainy monsoon, 

 which he had an opportunity of 

 observing. At midnight the wea- 

 ther was cloudV) and the sea was 

 particularly dark, when suddenly 

 it changed to a white flaming co- 

 lour all around. This bore no re- 

 semblance to the sparkling or 

 glowing appearance he had ob- 

 served on other occasions in seas 

 near the equator, but was a regular 

 white colour like milk, and did 

 not continue more than ten mi- 

 nutes. A similar phaenomenon, 

 he says is frequently seen in the 

 Banda sea, and is very alarming to 

 those who have never perceived or 

 heard of such an appearance be- 

 fore. 



This singular phaenomenon ap- 

 pears to be explained by some ob- 

 servations communicated to me by 

 Mr. Langstaff, a surgeon in the 

 city, who formerly made several 

 voyages. In going from New Hol- 

 land to China, about half an hour 

 after sun-set, every person on 

 board was astonished by a milky 

 appearance of the sea: the ship 

 seemed to be surrounded by ice 

 covered with snow. Some of the 

 company supposed they were in 

 soundings, and that the coral bot- 

 tom gave this curious reflection ; 

 but on sounding with 70 fathoms 

 of line no bottom was met with. 

 A bucket of water being hauled 

 up, Mr. Langstaff examined it in 

 the dark ; and discovered a great 

 number of globular bodies, each 

 about the size of a pin's head, 

 linked together. The chains thus 

 formed did not exceed three inches 



inlength, and emitted a pale phos- 

 phoric light. By introducing his 

 hand into the water, Mr. Lang- 

 staff raised upon it several chains 

 of the luminous globules, which 

 were separated by opening the fin- 

 gers, but readily re-united on be- 

 ing brought again into contact, 

 like globules of quicksilver. The 

 globules, he says, were so trans- 

 parent, that theycould not be per- 

 ceived when the hand was taken 

 into the light. 



This extraordinary appearance 

 of the sea was visible for two 

 nights. As soon as the moon ex- 

 erted her influence, the sea chang- 

 ed to its natural dark colour, and 

 exhibited distinct glittering points, 

 as at other times. The phaenome- 

 non, he says, had never been wit- 

 nessed before by any of the com- 

 pany on board, although some of 

 the crew had been two or three 

 times round the globe. 



I consider this acount of Mr. 

 Langstafl'very interesting and im- 

 portant, as it proves that the dif- 

 fused light of the sea is produced 

 by an assemblage of minute me- 

 dusae on the surface of the water. 



In June 1806, I found the sea 

 at Margate more richly stored with 

 the small luminous medusae than 

 I have ever seen it. A bucket of 

 the water being set by for some 

 time, the animals sought the sur- 

 face, and kept up a continual 

 sparkling, which must have been 

 occasioned by the motions of in- 

 dividuals, as the water was per- 

 fectly at rest. A small quantity 

 of the luminous water was put 

 into a glass jar, and on standing 

 some time, the medusae collected 

 at the top of the jar, and formed a 

 gelatinous mass, one inch and a 

 half thick, and of a reddish or 



