318 FAIRY RINGS. 



by it, but just the external ring of this cylinder, where the grass can 

 have access to the air ; since without air nothing can be calcined. 

 This earth after having been so calcined becomes a richer soil, and 

 either funguses or a bluer grass for many years mark the place. 

 That lightning displaces the air in its passage is evinced by the loud 

 crack that succeeds it ; which is owing to the sides of the aerial va- 

 cuum clapping together when the lightning is withdrawn. That 

 nothing will calcine without air is well understood, from the acids 

 produced in the burning of phlogistic substances, and may be agree- 

 ably seen by suspending a paper on an iron prong, and putting it 

 into the centre of the blaze of an iron furnace ; it may be held 

 there some seconds, and may be again withdrawn, without its being 

 burnt, if it be passed quickly into the flame, and out again, through 

 the external part of it which is in contact with the air. I know 

 some circles of many yards diameter of this kind near Foremark, in 

 Derbyshire, which annually produce large white funguses and 

 stronger grass ; and have done so, I am informed, above thirty years. 

 This increased fertility of the ground by calcination or charring, and 

 its continuing to operate so many years, is well worth the attention 

 of the farmer ; and shews the use of paring and burning new turf in 

 agriculture, which produces its effect, not so much by the ashes of 

 the vegetable fibres, as by charring the soil which adheres to them. 

 These situations, whether from eminence or from moisture, which 

 were proper once to attract and discharge a thunder-cloud, are 

 more liable again to experience the same. Hence many fairy-rings 

 are often seen near each other, either without intersecting each 

 other, as I saw this summer in a garden in Nottinghamshire, or in- 

 tersecting each other, as described on Arthur's seat, near Edinburgh, 

 in the Edinb. Trans. Vol. II. p. 3." 



[Bot. Gard. Additional Note xiii. p. 26. 



There are, nevertheless, various objections to this hypothesis ; 

 and which seem rather to establish the opinion that these singular 

 patches are the result of the insidious operation of the agaricus 

 orcades, a fungus common to the moist wastes of our own country. 

 Mr. Gilbert White first observed, with his usual correctness, that 

 the cau^e of the Fairy-rings exists in the turf, and is conveyable 

 with it ; " for the turf of my garden walks," says he, " brought 

 from the down above, abounds with these appearances, which vary 



