LUMINOUS INSECTS. 



341 



of phosphureted hydrogen, as has been suggested by some, 

 which must necessarily have been momentary. But that the 

 ignis fatuus mentioned by Derham as having been seen by 

 himself, and which he describes as flitting about a thistle 1 , 

 was, though he seems of a different opinion, no other than 

 some luminous insect, I have little doubt. Mr. Sheppard 

 informs me that, travelling one night between Stamford and 

 Grantham on the top of the stage, he observed for more than 

 ten minutes a very large ignis fatuus in the low marshy 

 grounds, which had every appearance of being an insect. The 

 wind was very high : consequently, had it been a vapour, it 

 must have been carried forward in a direct line ; but this was 

 not the case. It had the same motions as a Tipula, flying 

 upwards and downwards, backwards and forwards, sometimes 

 appearing as settled, and sometimes as hovering in the air. — 

 Whatever be the true nature of these meteors, of which so 

 much is said and so little known, it is singular how few 

 modern instances of their having been observed are on record. 

 Dr. Darwin declares, that though in the course of a long life 

 he had been out in the night, and in the places where they 

 are said to appear, times without number, he had never seen 

 any thing of the kind : and from the silence of other philoso- 

 phers of our own times, it should seem that their experience 

 is similar. 2 



1 Phil. Trans. 1729, 204. 



2 A paper by Richard Chambers, Esq., in the Magazine of Nat. Hist. (New 

 Series, i. 353.), relates several facts observed by the celebrated botanists Mr. 

 James Dickson, and Mr. Curtis, author of the Flora Londinensis, T. Stothard, 

 Esq. R. A. (who was, as before mentioned, a zealous entomologist), his father, 

 Mr. A. Chambers, and Joseph Simpson, a fisherman, at Frieston near Boston, all 

 strongly corroborating the above statements as to the probability that at least some 

 ignis fatui are caused by luminous insects. George Wailes, Esq., on the other 

 hand, has given in the Entom. Mag. i. 351. the result of his father's observations 

 and his own, and has also quoted those of Major Blesson, from Jameson's Edinb. 

 New Phil. Journ. for Jan. 1833, in proof " that the moving ignis fatuus of this 

 country always owes its origin to the spontaneous ignition of gaseous partieles" 

 (meaning, I presume, phosphureted or carbureted hydrogen gas), and conse- 

 quently cannot be an insect. Without pretending to deny that these gases may 

 be a cause of stationary ignes fatui, I confess myself quite unable to conceive of 

 a small mass of these inflammable materials " about the size of the hand " 

 moving at the height of " three feet from the surface of the ground " and " for 

 the distance of fifty yards nearly parallel with the road," as in the instance seen 

 by Mr. Wailes's father, and being luminous all the time. A mass of hydrogen 

 gas and its compounds, as is well known, whether large or small, when once in- 

 flamed (and if not inflamed it cannot be luminous), burns but for an instant ex- 

 cept renewed by a fresh supply. In passing the Appenines between Bologna 



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