126 Appendix. 



feet thick ; and ships sailing over 1,200 miles away, were covered 

 by the rain of ashes. The mass of matter sent forth was esti- 

 mated to be 65,000,000 cubic yards, and the distance covered 

 was estimated to be two million square miles. The Sandwich 

 Island volcano of Mouna Lea furnishes also some remarkable in- 

 stances of this character, and the ashes, together with what is 

 known as Pelix hair or spun glass, have been carried to immense 

 distances. According to Sir Charles Lyell, from an eruption 

 which took place on the island of Tambawa, lying east of 

 Jamaica, ashes were carried over 1,000 miles, forming a mass two 

 feet thick, through which vessels passed with difficulty. Notices 

 and accounts of the fall of dust traceable to a volcanic origin, 

 throughout Europe, are numerous, and are easil} found. 



Before concluding the mention of these cases, however, it 

 will be well to note one which is mentioned in the Jour. Chem. 

 Soc., Vol. X. 



A cyclone which passed over Africa on the 28th of Febru- 

 ary, 1872, appeared in Sicily on March 5th. The wind blowing 

 violently on the 9th, loth and nth, rain fell, mixed with fine 

 dust. The dried dust consisted of 75 parts argillaceous particles 

 colored by iron, n.6 parts calcareous matter, and 13.19 parts 

 nitrogenous organic matter. Its specific gravity was 2.52. Ex- 

 amined microscopically, the dust was found to contain an abun- 

 dance of such organic matter as hairs, fibres, etc., together with 

 five classes of organisms. To the suggestion that the sand might 

 have been derived from the African Sahara, the author replies 

 that his examination of the sand of that desert shows that it has 

 an entirely different composition, no organisms are present, and 

 therefore, in spite of the similarity of specific gravity, and not- 

 withstanding that the latter contains many objects well known in 

 the vicinity, such as the hairs of the olive leaf, etc., he concludes 

 that the volcanic dust was not of African origin, and gives his 

 reason for thinking it to be derived from South America. 



We have thus presented, in a very incomplete manner, the 

 facts and circumstances bearing upon the fall of snow colored 

 with dust, in Michigan and the West, and also those relating to 



