134 REPORT — 1891. 



Class C— Damage by Lightning. 



Nos. 1-4. Rear-Admiral Maclear. 

 „ 5-6. Seuor Don Augusto Arcimis. 

 „ 7-10. Mr. J. Hopkinson. 



Class D.— Damage by Stoems. 

 Nos. 1 and 2. EflEect of hailstorms of August' 2 and 3, 1879, from Mr. G. 

 W. Whipple. 



Class E.— Electric Spaeks. 



Nos. 1-10. lUustrating forms of discharge, from Mr. A. W. Clayden. 

 „ 11-18. Explaining dark flashes, from Mr. A. W. Clayden. 



Class F. — Snowfall, &c. 



Nos. 1 and 2. Snow-crystals, from Mr. A.. W. Clayden. 

 „ 3 and 4. Drifts, March 11, 1891, from Mr. R. G. Dnrrant. 



Class G. — Glaciers. 



No. 1. Ice-cliffs of the empty Meerjelensee, 1889, from Mr. Greenwood Pim, 

 Nos. 2-7. Various glaciers from Mr. Greenwood Pim. 



Class H.— Hoae-feost. 

 Nos. 1-8. From Mr. A. W. Clayden. 



Class M. — Mi.scellaneous. 

 Nos. 1-3. Shadows of a camera on fog, from Mr. A. W. Clayden. 



Registration of Photographs in other Collections. 



This section of tbe work has hardly been commenced. Several pro- 

 minent firms of professional photographers have been approached with a 

 view to tabulating the pictures they possess, but they have not offered 

 any special facilities. This is to be regretted in some ways, but there 

 seems x-eason to hope that another year something of the kind might 

 be done. 



The fine collection in the possession of the Royal Meteorological 

 Society has been examined. It contains a large number of very beautiful 

 cloud studies by Dr. Riggenbach and M. Paul Garnier, but information 

 as to the methods adopted by these observers and as to the conditions 

 under which the pictures were taken is at present wanting. Neverthe- 

 less the work of registering these photographs would have been taken 

 in hand had it not been all but impossible to' describe them properly. 

 The chaotic condition of cloud nomenclature seems to render it impossible 

 to describe the minute diSerences of structure so admirably shown in the 

 pictures in terms which would be generally intelligible. Many cloud 

 forms, especiallj' among the thinner types, are intimately related to one 

 another, some being only transitional phenomena during the passage of 

 one stable form into another. Tour committee have therefore laid special 

 stress in their instructions to observers upon the importance of securing 

 series of cloud jjictures at short intervals delineating cloud changes and 

 showing, as far as possible, the relations between various forms. Until 

 some satisfactory system of nomenclature has been devised, or until your 



