Appendix. HI] 



six hundred square miles in Michigan, after crossing Lake 

 Michigan. 



Our informant also vouches for the statement that the same 

 phenomenon was noticed in Illinois, sixty miles south-west of 

 Chicago, and also at Janesville, Wis. The wind, at both of 

 these places, being in the same direction as in Michigan. 



In order to confirm this latter statement, I have written to 

 the Signal Service Bureaus at different points in Illinois, Missouri 

 and Wisconsin, but as yet no reply has been received. 



That some idea may be formed as to the amount of this 

 sediment which fell, a square yard was measured off at Holland 

 soon after the storm had ceased, and after evaporation the upper 

 layer of snow yielded 87 grains of solid matter. Assuming that 

 the fall took place over an extent of 400 square miles, and that 

 it was equal over the whole, we may easily calculate that with 

 this fall of snow there were precipitated about 7,000 tons of 

 solid or earthy matter. 



Having now the true facts of the case, it remains to account 

 for this, to say the least, singular phenomenon, in some rational 

 way. It is evident, both from appearance and from analysis, 

 that the sediment from either locality is identical in almost every 

 respect, and is without doubt of the same origin ; both have the 

 same color; both contain fibrous matter; and a description of 

 the one will to a great extent answer for the other. Under the 

 microscope the substance shows itself to be composed of organic 

 and inorganic matter. The inorganic portion apparently con- 

 sists of small particles of silica, some of which seem to be col 

 ored with iron and earthy matter. These particles of silica have 

 not the appearance of having been water worn, but the fracture 

 of them is sharp and well defined, having all the appearance of 

 being recently broken or reduced to powder, without the abrasive 

 action of water. There are also to be seen fine threads or fibres, 

 perfectly transparent, and having a resemblance to fine tubes of 

 glass or silica. These tubes present no appearance of organic 

 structure, and as a whole, nothing either of a vegetable or animal 

 structure is to be detected. Small particles of organic matter, 



