192 PROCEEDINGS OF THE CALIFORNIA 



subjected to a very careful chemical and microscopic examination. 

 It revealed silicious matter, and also a peculiar cellular formation, 

 ■which burned somewhat like asphaltum. 



He had no evidence that the silicious matter was a portion of the 

 sediment. It might have been a portion of the dust on the deck 

 before the peculiar deposit fell. What the other substance was 

 could not be determined, as the quantity of sediment furnished 

 was so small that the reactionary effects of the acids could only be 

 observed under a microscope. Mr. Hanks regretted that the sample 

 furnished him was so small in quantity as to preclude better results. 



Dr. KelloiTir thought that the difference in showers might to a 

 certain extent account for the deposit. It was not impossible that 

 showers of various substances formed in the atmosphere, somewhat 

 in the same manner as do rain showers. 



Mr. Hanks said the existence of cosmical dust was established 

 beyond a doubt ; and also the fact that this dust is constantly set- 

 tling on the tops of mountains. 



Dr. Cooper alluded to the fact that the meteorites which have 

 fallen within the last few years were more composed of carbona- 

 ceous matter and less of iron than formerly. He thought a possible 

 explanation of the sedimentary shower might be found in the frequent 

 burning of lignite beds, which takes place on Whidby's Island, near 

 the Straits of Fuca. These burning beds are sometimes covered 

 by sand. It might be that the dense smoke arising from the fires 

 would bear upwards with it fine silicious particles, which it caught 

 passing upward through the sand. 



Dr. Gibbons said he had no doubt that there were extraneous 

 substances in solid form, but in a state of minute division, carried 

 through the atmosphere to an immense height. They are also 

 carried by winds and by smoke. All these are sources of atmos- 

 pheric cloud. The lower strata of the atmosphere being heavier 

 than the upper, they would seem to be better adapted to floating 

 these particles. But yet they are carried and do remain an im- 

 mense distance up in the atmosphere. Winds take up sand and 

 carry it hundreds, perhaps thousands of miles. Immense quanti- 

 ties of sand are in this way borne from the coast of Africa, five 

 hundred or a thousand miles. The presence of silica in the sedi- 

 ment tested by Mr. Hanks was, therefore, easily accounted for. 



