12 

 I turn now to the special part of this address. 



WiLL-o'-THE-WlSP. 



1 wish to devote a few minutes to-nigbt to the consideration of 

 a subject to which I alluded in a paper on "Luminous Insects," 

 read before this Society a few years ago''', viz. : the phenomenon 

 known variously as Will-o'-the-Wisp, Jack-o'-Lantern, Ignis 

 Fatuus, etc. 



We must all be familiar with the popular superstition 

 concerning this mysterious light, regarding it as a mischievous 

 sprite dancing before the wayfarer, deliberately luring him on into 

 the marsh or bog to which he ultimately falls a victim. It is 

 important that we should bear this idea in mind when considering 

 the accounts of its appearance that I am going to put before you, 

 for you will see that some of these accounts obviously relate to 

 phenomena of a different nature. In order to have definite 

 authority that the above is a correct statement of the generally 

 accepted idea of the meaning of the term, I will quote the Oxford 

 Dictionari/ : — ''■ Ljnh Fatuus. A phosphorescent light seen hovering 

 or flitting over marshy ground, and supposed to be due to the 

 spontaneous combustion of an inflammable gas (Phosphoretted 

 Hydrogen) derived from decaying organic matter. 



" It seems to have been formerly a common phenomenon, but is 

 now exceedingly rare. When approached the Ignis Fatuus appears 

 to recede and finally to vanish, sometimes re-appearing in another 

 direction. This led to the notion that it was the work of a 

 mischievous sprite intentionally leading benighted travellers astray." 



Probably you will all agree that this is a substantially correct 

 resume of the actual appearance, the theoretical cause, and the 

 hypothetical purpose of the phenomenon we know as the Will-o'-the- 

 Wisp. 



Now just note its appearance : — a phosphorescent light seen 

 hovering or flitting over marshy ground. (We will not cavil for the 

 moment over the term ' phosphorescent ; ' it looks like a phosphorescent 

 light, whether it is so or not). Obviously then it must be visible 

 for some measurable time during which it moves irregularly about 

 (hovering or flitting), details which quite accord with, and indeed 

 are essential to its hypothetical purpose, viz., to lead benighted 

 travellers astray. But what about its theoretical cause: — ' supposed 

 to be due to the spontaneous combustion of an inflammable gas 



♦ May 28th, 1914. 



