Remarks on Atmospheric Dust. 135 
referred to, are doubtless true, but, as I apprehend, attribu- 
ted to wrong causes. Iam not disposed to question that 
m which there is not a sufficient breeze sometim 
course of the twenty-four hours, to set in motion what we 
call atmospheric dust. And occasionally immense quan- 
tities are raised. In the stillest times, vegetables and 
trees are constantly depositing decayed matter, and some 
accompany it there. Besides, the dust which is visible at 
Sea, is visible only when the ship is nearly or quite becalm- 
ed ; and may it not then arise in a great measure from the 
deck of the ship? : : 
Mr. R. “calculates that on an average, from six to 
twelve inches are accumulated over the ground in one hun- 
dred years.” Taking his lowest estimate, six inches for 
