342 Weld /OGIWINAUIL Ol? CIE CILOEIZ. 
letter to Mr. Leverett, only two days before his death, he added 
to the immediate purpose of his communication a discussion of 
the mode of deposition of the loess. By permission. this is here 
added because of its interest as one of the latest, possibly 
indeed the very last, scientific discussion which he committed to 
writing. C.. 
[Extract from a letter written by Professor James D, Dana to Mr. Frank 
Leverett, dated April 12, 1895, but two days before his death.| 
“With regard to the eolian work along valley plains, I think great caution 
is necessary because eolian work is of a fitful kind. The more powerful winds 
blow in gusts, or rather a succession of them, and each of the gusts is of 
rather narrow limit; and in each gust great velocity is succeeded by a decline 
in which the depositions vary accordingly as to coarse and fine and limit. 
Making loess— unstratified —by the winds would require a steady breeze 
sufficient to move the light earth or sand long in a common direction, but 
too near unvarying in force or velocity to produce alternations from coarse to 
fine. It is an even kind of work that winds are not often fit for. They heap 
up at the slightest provocation, strike the ground and glance off when of great- 
est force. It takes something of a breeze to even start the dust of a road, 
because the dust is 2000 times heavier than the air and the air near the 
ground slips over the surface readily without disturbing it. Excuse me for 
thus discoursing on wind work. 
“Do you know what is the size of the largest pebbles taken up by a storm 
wind from a level surface and carried, as it carries sand, for a few yards? 
The houses in the track of some of the great western gales must have win- 
dows sometimes broken in this way; and perhaps their owners, if reliable, 
could give some facts worth knowing.” 
eae 
AN additional loss has been suffered by geology in the recent 
passing of Professor Henry B. Nason. While primarily a chem- 
ist and mineralogist, Professor Nason was an earnest and con- 
scientious student and teacher of geological phenomena. An 
exceptionally wide traveler, his personal familiarity with Ameri- 
can and foreign deposits was unusually extensive, and gave to 
his instruction breadth and balance. His primary geological 
interest lay in the field of volcanic phenomena. Although an 
