274 A. LIVERSIDGE. 



Dr. H. B. Guppy, in "Nature," June 9th 1881, says that 

 in the spring of 1878 his attention was directed to the 

 dust-winds which are of frequent occurrence in the valley 

 of the Yang-tse in the warm and dry season of the year. 

 According to his observations at Hankow, they sometimes 

 had the appearance of a dense mist, and at other times the 

 air seemed to be penetrated by a fine haze, and in all cases 

 a fine and impalpable dust was deposited, which was with 

 difficulty excluded from the interior of the houses. Their 

 duration lasted from a few hours to two days. He con- 

 cluded that they are not local phenomenon from the fact 

 that one was experienced simultaneously from Hankow to 

 Chinkiang a distance of nearly 450 miles. The dust resem- 

 bles the loess of the alluvial plains of the Yang-tse, and is 

 generally made up of siliceous or calcareous particles from 

 toVo to t^o inch in size, and vegetable debris. From a 

 study of the meteorological and electrical conditions of the 

 atmosphere, he does not think they are due to sudden 

 breezes. 



Prof. S. P. Langley, of the Allegheny Observatory, Penn., 

 in speaking of the red sunsets seen all over the world, says 

 ("Nature," 31/1/84) "we know of but two likely causes: 

 one is the advent of an unusual amount of meteoric dust. 

 While something over ten millions of meteorites are known 

 to enter our atmosphere daily, which are dissipated in dust 

 and vapour in the upper atmosphere, the total mass is small, 

 compared with the bulk of the atmosphere itself, although 

 absolutely large. It is difficult to state precisely what 

 this amount is . . . approximately not greatly more 

 than 100 tons nor greatly less than 1,000 tons a day. 



"Taking the largest estimate as still below the truth, 

 we must suppose an enormously greater accession than this 

 to supply a quantity, sufficient to produce the phenomenon 

 in question ; and it is hardly possible to imagine such a 



