230 Atmospheric Electricity [April, 



Till something more is known, however, and known more 

 definitely, as to the nature of cloud and fog constituents, we can 

 scarcely expect much progress in this department; and I would 

 commend the subject to aeronauts and microscopists. Mr. Proctor, 

 in an interesting paper on the subject of rain,* quotes De Saussure, 

 Kamptz, &c, against Sir J. Herschel and Tyndall, appearing to 

 incline to the views of the latter writers. He does not, however, 

 allude to electrical action in enumerating the causes of rain. Yet 

 it seems to me there is no reason to believe that the aggregation 

 or dissociation of clouds and the condensation of their particles is 

 greatly due to the influence of this force. That the movements of 

 cloud and mist are accompanied by strong electrical action has been 

 shown by the experiments of Mr. Crosse, of Bromfield, and 

 Mr. Eonalds ;f and it is but reasonable to think that this action may 

 have great influence on contiguous vapour, though unaccompanied 

 by a disruptive discharge, or any luminous appearance. My 

 observations induce me to think that electricity is also indirectly 

 the cause of those peculiarities of refraction which depend upon the 

 molecular condition of the vapour mediae through which the light 

 passes, viz. — Halos, Parhelia, Paraselense, &c. ; and I may here 

 remark that these phenomena appear to have been unusually 

 abundant during the past year, which has also afforded such 

 exceptional displays of aurora, &c. 



On the 21st September, a halo, of large diameter, say 60°, 

 corresponded in position with the cirrhus clouds which formed the 

 refracting medium. This halo followed the irregularities of the 

 cloud to a considerable extent. Its disappearance was almost 

 instantaneous, being caused apparently by the approach of a large 

 mass of cumulus in the lower region of the sky. Almost as soon as 

 the latter touched the lower part of the circle, the halo vanished. 

 The irregularities in the circle of light at one time took the form of 

 a series of separate arcs, which bent inwards, and appeared to be 

 composed of half-dissolved cirrhus. These irregularities of form 

 were also very conspicuous in a remarkable halo which was seen on 

 Friday evening, December 19th. This assumed a spheroidal form, 

 and was intersected by streaks of cirrhus, which changed their 

 form rapidly, and showed a prismatic refraction like that of the 

 halo itself. The vanishing of the first-mentioned halo was perhaps 

 caused by an alteration in the constitution of its crystals or vesicles 

 resulting from the electric action of the cloud below. 



The next appearance I have to describe was of a singularly 

 beautiful form and perfect definition. It appeared imbedded in a 

 mass of homogeneous vapour, and consisted of two distinct rings, 

 the inner one of a deep cobalt blue. This ring was distant from 



* 'Intellectual Observer,' December, 1867. 

 f Tide Sir S. Harris's < Electricity.' 



