4:68 Mr. C. Tomlinson on the Ignis Fatuus, 



dark night. For there in a cold winter, and when the ground 

 is covered with snow, they are in greater plenty than in the 

 hottest summer. Those also are observed in winter, which 

 Gassendus says are seen at Rogon, a town of Provence. They 

 appear more frequently in hot than in cold countries. In 

 Italy near Bononia are the greatest, and in greatest plenty. 

 Sometimes they vanish on a sudden, and presently shine out 

 in another place. They are generally at the height of about 

 six feet from the ground. Now they dilate themselves, and 

 now contract. Now they go on like waves, and rain as it 

 were sparks of fire, but they burn nothing. They follow 

 those that run away, and fly from those that follow them. 

 Some that have heen catched were observed to consist of a 

 shining, viscous, and gelatinous matter, like the spawn of 

 frogs, not hot or burning, but only shining ; so that the 

 matter seems to be phosphorous, prepared and raised from 

 putrefied plants or carcases by the heat of the sun ; which is 

 condensed by the cold of the evening, and then shines. Yet 

 I do not think that the matter of all is the same, for without 

 doubt those of Bononia differ from those of Holland. It is a 

 mere fiction that these fires are evil spirits or wandering 

 ghosts, misleading travellers out of mere spite, to plunge 

 them into ditches and bogs as some trifling Philosophers have 

 told us/' 



In the above passage there is much admirable description 

 of the Ignis Fatuus, but the writer cannot reconcile the phe- 

 nomena as due to one source, for he does not think that " the 

 matter of all is the same.'"' It is clear that some of the 

 phenomena refer to gaseous meteors, others to electrical, and 

 others again to phosphorescent*, but further advances in natural 

 knowledge were required before these distinctions could be 

 made clear. 



The first step towards a true explanation of the Ignis Fatuus 

 was taken by Priestley, who, in 1767, began his " Experi- 

 ments and Observations on different kinds of Air," and thus 



* Iu the Philosophical Magazine for August and December 1888 I 

 have cited a number of examples of low lying electrical meteors. These 

 may he multiplied to almost any extent, but they must not be confounded 

 with the ignis fatuus. Whether phosphorescent lights are ever seen 

 hovering over graves, forming what are called " corpse candles," has not 

 been decided by scientific evidence unless the testimony of Reichenbach's 

 sensitive patients be taken as such. Some years ago the inhabitants of a 

 small town in Scotland were alarmed by a luminous appearance in the 

 neighbouring wood. It was seen during several evenings after sunset. 

 Most of the inhabitants were too timid to investigate the cause, but one 

 bo]d spirit ventured and found the light to proceed from a large putrescent 

 fish which some one had thrown up into a tree. 



