494 DEVELOPMENT OF ILLUMINATION. 



earned on by moonlight in order to escape the heat <>t' the day. While 

 moonlight is 450,000 times less bright than daylight, under certain 

 favorable conditions the lighl seems intense and ample for many 

 purposes. 



The well-known phosphorescence <>)' lichens has been found to give 

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

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

 and moonflower. 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 yielded by the animal kingdom. 



When the animal kingdom is reached, numerous examples of light 

 phenomena connected with vital processes are found. The familiar 

 firefly of northern latitudes frequently renders summer nights lumi- 

 nous, while the tropical noctilucidae yield 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 tree- like a fiery 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 1 have read the finest print of 

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

 under a common glass tumbler, and with distinctness 1 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 <d' 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 bysenoritas for adorning their tresses. 

 Prescotl narrates the terror they inspired in the Spaniards in L520. 

 "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 t«> read by it. These wandering fires seen in the darkness 

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

 locks,' so -ays Bernal Diaz."" 



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

 very important, and the investigations carried on at the Smithsonian 

 Institution a few year- 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 id' the light emitted by 

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

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

 refrangibility. The heat given out is scarcely appreciable, being less 

 than one-half of 1 percent of that produced by an equal amount of 



'Kidder and Fletcher, Brazil an. I the Brazilians, Phila., 1857, p. 293. 



