LIFE OF JAMES DWIGHT DANA 



copy of the map, as large as the page. The map is a 

 very instructive one, orographically, and especially as 

 regards the Appalachian region. 



" I, too, feel age encroaching on old privileges. I used 

 to have a spring in my walk, and get delight out of it. 

 But for a little over a month, owing to a weakening of 

 some strings, my heart has compelled me to take what I 

 should before have called a creeping gait. Such en- 

 croachments are reminders that the end is coming. But 

 it will be peace, rest, and, I believe, joy unending. Life 

 were worth living if it were only for the end." 



The end of that man was peace. He continued his 

 work until almost the last day. Final proofs of one of his 

 books had been read and corrected. Four brief notices 

 from his pen appeared in the March number of the Jour- 

 nal of Science. A letter to Mr. Frank Leverett (on the 

 work of the wind in moving sand and pebbles) was dated 

 April 1 2th.* On that same day the venerable student 



* An extract from this letter is here given, to show the clearness of the 

 worker's mind until the very last. It is quoted from the Journal of 

 Geology : 



" With regard to the eolian work along valley plains, I think great cau- 

 tion is necessary, because eolian work is of a fitful kind. The more power- 

 ful 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 direc- 

 tion, 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 greatest force. It takes something of a breeze to even start the 

 dust of a road., because the dust is two thousand 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 windows sometimes broken in this way ; and perhaps their owners, if 

 reliable, could give some facts worth knowing." 



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