144 PHOSPHORESCENCE. 



upon them, there are materials and means enough 

 for the production of ten times the number of ignes 

 fatui that ever were observed. Church-yards are 

 very favourable for their appearance; and hence 

 probably the reason why they have been associated 

 with spirits, and considered objects of terror, while 

 they are in themselves not only perfectly harmless, 

 but exceedingly beautiful, especially when seen in 

 lonely places and through between trees. 



In tropical countries, where the action of the sun 

 is more powerful during the day, and longer sus- 

 pended during the night than with us, and where 

 consequently both growth and decomposition go on 

 much more rapidly, those airy meteors of the night 

 are much more common than they are with us. 

 They are more common at sea too than they are on 

 land ; though there they seldom rise above the sur- 

 face unless the water is agitated. But when that is 

 done, in certain states of the weather, namely, after 

 long calms, when the water has not been much dis- 

 turbed, there is a ripple of light at the bows of the 

 vessel, and her wake bears some resemblance to the 

 tail of a comet. Every splash of the oars fling? 



