Phosphorescence of the Sea 515 



saw the southern sea during a voyage to Siam luminescent with 

 sparkles which attached themselves to linen, resembling a glowworm, 

 alive and bluish. He also noted larger masses of light, a foot in 

 diameter, " which might come from fish which shine naturally." 



Regarding the origin of the light, Tachard (1688) wrote: " I do 

 not believe one errs in searching anywhere for the cause of this light 

 than in the nature of sea water, which is salt, nitre, and all the other 

 materials of which chemists make those phosphors which inflame 

 immediately on being agitated and become luminous. . , ." Tachard 

 then continued. 



It is not only when the sea is agitated that it becomes brilliant but we 

 have seen more [lights] toward the equator during the calm after the 

 sun sets. They appear to us as an infinity of little flashes, rather feeble, 

 which go out of the sea and disappear. We attribute the cause to the 

 heat of the sun, which has, as it were, impregnated and filled the sea 

 during the day with an infinity of fiery and luminous spirits [d'esprits]. 

 These spirits after dark reunite to pass out in a violent state [from the 

 sea], where the sun has put them, attempting in its absence to be set at 

 liberty and fashioning these little flashes in escaping under the cover of 

 the night. 



The idea that phosphorescence of the sea came from the sun per- 

 sisted for many years. 



Worms' (1709) speculations, as quoted by C. G. Ehrenberg (1834: 

 422) , will serve to climax the series. After describing the entire sur- 

 face of tropical seas sparkling with light, observed during a voyage 

 to Persia and the East Indies, he suggested that the light came from 

 the salt and saltpeter of the sea water which, by rapid movement, 

 kindled themselves and became luminous. This was actually a com- 

 bination of Papinian and Cartesian ideas, but for good measure 

 Worms also surmised that during the day the sunlight impregnated 

 the sea water with an infinite number of fiery ghosts which in the 

 evening combined with each other as a great many small lightnings 

 which vanished as they came out of the sea. The comparison with 

 lightning indicates a very definite Aristotelian influence (see Chap- 

 ter I) , since Worms did rely chiefly on the opinion of others in sug- 

 gesting an explanation. It is quite obvious that the light of the sea 

 was completely unexplained in the early eighteenth century. 



It is rather surprising that greater interest was not taken in the 

 study of sea luminescence by men primarily dealing with biological 

 matters, for example the great microscopists of the period. Marcello 

 Malpighi (1628-1694) , Jan Swammerdam (1629-1682) , Antony van 

 Leeuwenhoek (1632-1723) Robert Hooke (1635-1702) , and Nehe- 

 miah Grew (1641-1712) all overlooked the many microscopic lumi- 



