22 History of Luminescence 



wingless larva on the ground. The second is the low opinion of the 

 brightness of a firefly flash. Far from amazement at the ability of a 

 tiny creature to produce a light without accompanying heat, the 

 firefly was rated in Buddhist scriptures near the bottom of the list 

 of luminous objects. In this respect the attitude is similar to that of 

 the Arabs, whose name for a firefly is derived from that of a man so 

 stingy that he always kindled a fire too small to be of any value to 

 anyone (see Chapter II) . 



Knowledge of luminescence in ancient India must not be con- 

 cluded without mention of the luminous cobra-stone of India and 

 Ceylon, although the date of the legend is unknown, and the story 

 sounds highly improbable but completely fascinating. The best 

 account has been related by Professor H. Hensoldt,*^ who obtained 

 one of the stones, called " Naja-Kallu," during a stay at Point de 

 Galle, Ceylon. It is said that about one cobra in twenty carries 

 around in its mouth a small luminous stone that it places in the 

 grass at night to attract fireflies, which the cobra then proceeds to 

 eat. Hensoldt caught fifty cobras without finding a stone but one 

 night in the field with a Tamil coolie he saw a cobra resting by 

 what he thought was a luminous spot. He wished to kill the cobra 

 at once but the Tamil implored him not to because the snake is 

 alleged to be particularly dangerous when watching the Naja-Kallu. 

 However, on the next night the Tamil saw the cobra in the same 

 place and obtained the stone by climbing a tree and throwing ashes 

 over it. The ashes were collected and sifted after the snake had 

 left. The stone was " a semitransparent water worn pebble of yel- 

 lowish color, about the size of a small pea, which in the dark, espe- 

 cially when previously warmed, emitted a greenish phosphorescent 

 light." Chemically it was a fluorite, some varieties of which (chloro- 

 phane) are said to be sufficiently phosphorescent to shine all night 

 long after exposure to the sun's rays. The pebble no doubt existed 

 but the part played by the cobra is reminiscent of another more 

 recent story regarding the Indian baya-bird or bottle-bird (Ploceus 

 baya) , which is alleged *^ to stick fireflies in the mud-pellets of its 

 bottle-shaped nest in order to scare marauding animals from the 

 eggs and young birds. 



Greece 



Among the ancient Greek philosophers from Thales of Miletus 

 {ca. 640-ca. 546 b. c.) and his pupil Anaximander {ca. 611-547 b. c.) 



" H. Hensoldt, The Naja-Kallu, or cobra stone, Harpers Monthly Magazine, 80: 546- 

 540, March, 1890. 



*8H. A. Severn, Nature 24: 165, 1881. 



