NEPTICULA SERELLA AT INGLEBOROUGH. 



pursued by the blast is not the return, but the intake air-ways ; and 

 yet there are those who wall persist in attributing such explosions to 

 gas, and not to the manifestly true cause — dust. 



Nearly all dusts include yellowish, reddish, or purplish fragments, 

 very often triangular in shape, and with more or less clearly marked 

 conchoidal fractures. They are tolerably abundant — for example in 

 the Herrington Maudlin Coal. If these coloured bodies originate in 

 Lycopodian spores (and they certainly closely resemble those seen in 

 the well-known spore coals of the Bradford 'Better bed' and Leicester- 

 shire ' Moira ') they may play an important part in the production of 

 explosions, for the resinous nature of the spores of the Selaginella 

 selaginoides of our northern hills is so well known that they were 

 formerly used in theatres to produce artificial lightning. Recent 

 German experiments have conclusively shown that some dusts are 

 exceptionally dangerous, and in such these spores may play a by no 

 means unimportant part. 



The following conclusions seem to be warranted by the foregoing 

 facts and experiments. All dusts are not alike dangerous. The 

 most dangerous dust really is the finest^ viz., the flocculent and 

 upper, less because of its composition than on account of its fineness. 

 This, therefore, should be watered rather than the bottom dust. 

 Dant always enters largely into the composition of such dust, but 

 the most dangerous contain a high percentage of exceedingly fine 

 coal, and even other more combustible matters as Lycopodian fossil 

 spores. The flint and steel of olden times finds its counterpart 

 in modern coal-pits, in the shot-flame or other start-point of an 

 explosion, as it finds in the dant of dry dusts a natural tinder to catch 

 the spark and hand it on to the sulphur match — the coal dust. 



Bottom dust, both from its coarseness and its very mixed 

 character, is much less dangerous. All parts of the pit are not alike 

 dangerous. The most dangerous parts of pits, as regards dust explo- 

 siofis, are the haulage-ways, and as regards gas explosio7is^ the working 

 face and the returns. This should be remembered in watering. 



The formation and accumulation of dust may be largely checked 

 by improved tubs or slower hauling, and by saturation of the intake 

 air-current with aqueous vapour, which latter means too will render 

 dust already formed innocuous and easy of removal. 



NO TE—LEPID OPTERA . 



Nepticula serella. — This is the name under which Mr. Stainton describes 

 the Poteiitilla iormeutilla feeding insect taken by Mr. E. R. Bankes at Ingle- 

 borough (see Nntnralist, March 1888, p. 82), in the current (April) number of 

 the ' Entomologists' Monthly Magazine,' at p. 260. —('.KG. T. Porri tt, Iludilers- 

 fiel d, Apr il 1888. 

 M.-iy 1 888. 



