494 DEVELOPMENT OF ILLUMINATION. 



carried on l)y moonlight in order to escape the heat of the day. While 

 moonlio-ht is 450,000 times less bright than daylight, under certain 

 favorable conditions the light seems intense and ample for man}' 

 purposes. 



The well-known phosphorescence of lichens has been found to give 

 considerable light during warm, moist nights in the summer. Certain 

 flowers are phosphorescent, or emit Hashes of light, as the tuberose 

 and moonfiower. In the vegetable world there are numerous sources 

 of light whose faintness causes them to escape ordinary observation. 

 As an aid to man, however, the light from the vegetable kingdom is 

 far less useful than that 3aelded by the animal kingdom. 



When the animal kingdom is reached, numerous examples of light 

 phenomena connected with vital processes are found. The familiar 

 firefl}" of northern latitudes frequently renders summer nights lumi- 

 nous, while the tropical noctilucidte jaeld an actual and valuable 

 illumination which has been utilized as light in several interesting 

 ways by the inhabitants of regions in which the insects are found. 



The distinguished traveler Kaempfer described the fireflies of Siam 

 as "settling upon the trees like a tier}' cloud,"" and in Brazil Gardner 

 compares them in brilliancy with "stars that have fallen from the 

 firmament and are floating about without a resting place.'' Kidder 

 says: "In the mountains of Tijuca I have read the finest print of 

 Harper's Magazine by the light of one of these natural lamps placed 

 under a conmion glass tumbler, and with distinctness I could tell the 

 hour of the night and discern the very small figures which marked the 

 seconds of a little Swiss watch. The Indians formerly used them 

 instead of flambeaux in their hunting and fishing excursions, and when 

 traveling in the night they are accustomed to fasten them to their feet 

 and hands. And they are used by senoritas for adorning their tresses. 

 Prescott narrates the terror they inspired in the Spaniards in 1520, 

 'The air was filled with "cocuyos," a species of large beetle which 

 emits an intense phosphoric light from its body strong enough to 

 enable one to read by it. These wandering fires seen in the darkness 

 of the night were converted by the besieged into an army of match- 

 locks,' so says Bernal Diaz."" 



The bearing of the light of the firefly on the light of the future is 

 very important, and the investigations carried on at the Smithsonian 

 Institution a few years ago may introduce a new epoch in illumination. 

 A brief account in the Philadelphia American states that "some inter- 

 esting experiments upon the nature and origin of the light emitted by 

 the firefly have lately been made by Prof. S. P. Langley. From the 

 spectroscope he finds the light to be of exceedingly narrow range of 

 refrangil)ilit3". The heat given out is scarcely appreciable, l)eing less 

 than one-half of 1 per cent of that produced b}^ an equal amount of 



"Kidder and Fletflier, Brazil and the Brazilians, Phila., 1857, p. 293. 



