Blaslus.] -^0^ [Feb. 18, 



the moon indicates rain, since its cause is tlie partial obsciiration of the 

 moon by the first haz}' clouds of an approaching Northeast storm. With a 

 knowledge of the connection between the clouds and movements of the 

 air, it will be comparatively easy for any one to i)redict for his own locality 

 the weather he is to expect from day to day. That this is practicable, is 

 proved by the experience of many, and by an able article on the subject 

 in the (xalaxy Magazine for November, by Mr. F Whittaker. 



In connection with the importance of clouds in practical meteorology is 

 the following statement in the scientific record of Harper's Monthly for 

 August, 1875, edited, I believe, by Prof Spencer P. Baird, of "Washington. 



"Dr. Ilildebrandsson, of Upsala, has published the results of a careful 

 study of observati(ms of cirrus clouds. Having secured by personal cor- 

 respondence a number of careful observers throughout Europe, he has com- 

 pared the observed movements of cirri with the prevailing clouds and 

 isobars at the surface of the earth. He finds that the cirrus clouds, in a 

 large majority of cases, flow out from areas of low barometer, and in toward 

 areas of high pressure, and, as he succinctly expresses it, the movement of 

 these clouds is toward a point some distance to the right of that toward 

 which the lower clouds move. "We had occasion, a few years ago, to an- 

 nounce precisely the same law, as deduced by Prof. Abbe for the United 

 States. It would seem, therefore, a law applicable to the whole of the 

 northern temperate zone, and is entirely in accordance with the mechanical 

 theory developed by Mr. Ferrel in a memoir published in 1860." 



The same fact is referred to in Harper's Weekly, January 15, 1876, as 

 follows : "Clement Ley so well known by his investigations into the move- 

 ments of storms, states, in reference to the movements of cirrus clouds, 

 whose laws have been investigated by Hildebrandsson and others, that his 

 own ol)servations fully confirm those of the latter as to the motion of the 

 upper clouds, with only this modification, that the vertical axis of a revol- 

 ving storm, about which the whole mass of air may be supposed to rotate 

 is not exactly vertical, but inclined backward." 



The writer evidently considers this isolated fact a very important discov- 

 ery, and it really is the first attempt on the part of the cyclonists to con- 

 sider the motion of clouds as well as their forms, and I might almost say 

 the first step towards bringing the clouds into connection with storms. 



As the cyclonists see the storm in the "area of low barometer," and the 

 opposite of the storm in the •' area of high barometer " their " rt/i,<i-cy clone." 

 it is natural that tliey should describe the motion of cirrus clouds in rela- 

 tion to these phenomena. But as the origin and nature of these phenomena 

 are as yet unknown to them, the cause of the motion of the cirrus clouds in 

 th§ direction described remains also unknown, and forms thus another puz- 

 zle besides the many we have already in the science. 



As to the precedency in the discovery of the fact in question, I would 

 draw your attention to my article — "New Theory of Storms," in the New 

 York Times, November 18, 1853, reprinted and more fully elaborated in 

 my recently published work — "Storms, their Nature, Classification and 



