PART 1.] 
Annual Report for 1871. 
black soil. “In very many places, when a large dylco is traceable through a valley, with ridges 
of gneissose rocks on either side, it frequently forms a marked lane of black clay up to the 
base rocks hounding it. And the dyke may often he traced across alluvial ground by this lane¬ 
shaped band of black clay, although no rock is visible.” Another fact in the physical con¬ 
figuration of the country arises from the resistance to decomposition of these trap dykes, which, 
therefore, very frequently occur along the top of the minor watersheds, where also most of 
the villages are placed. 
During the present season, Mr. Willson continues this examination to the east, complet¬ 
ing the northern portion of Dumoh district, for which no maps were available in former years. 
Mr. Fred. Mallet had been deputed towards the close of last year, when returning 
from Europe, to visit and examine the vicinity of Aden, with especial reference to the possi¬ 
bility of obtaining a good supply of pure water for the inhabitants of that important station. 
The results of this examination wore published immediately on his return. He showed that 
there was an abundance of water nearer to the foot of the hills a short distance from Aden, 
but that this became absorbed in the sands that intervened between these streams and the 
sea ; in other words, that there was an abundance of good water, but that artificial means 
of conducting it into Aden would be requisite. There seemed nowhere such a structure 
as would justify the expectation of procuring water by wells sunk on the artesian 
principle. 
Immediately on his return to India from this duty, Mr. Mallet was despatched to complete 
the geological examination of the southern part of the Mirzapur district which had been left 
unfinished. This would carry our knowledge of the geological structure of that country 
southwards to the long known coal-pits of Kota, which were to be examined in greater detail 
so soon as the maps of the adjoining country were available. This duty Mr. Mallet effectively 
performed. During the recess he has been engaged in working up his maps, &c., and in a 
careful examination of some interesting minerals he met with in that district in connection 
with extensive masses of Corundum, and of which a brief account is given in the present 
number of the “ Records of the Survey.” 
To Mr. Mallet I also entrusted the entire remodelling of our collection of minerals. 
When first the Museum was opened, the best series which our collection then afforded was 
brought together, and was arranged by Mr. H. F. Blanford for exhibition. This was unfor¬ 
tunately a very incomplete and poor series, but such as it was it proved useful. During subse¬ 
quent years, this collection has been steadily kept in view, as opportunity offered of acquiring 
additional specimens. And as a large number of additions bad been brought together by 
donation, by occasional purchase, and by exchange, it was determined to have the whole series 
remodelled. The collections had been arranged in accordance with the fourth edition of 
Dana’s system of Mineralogy (1854), but was now brought into agreement with the last or 
fifth edition, 1869. Up to last year the arranged collection represented 224 species by 1,460 
specimens. It now represents 358 species by 2,239 specimens. The number of specimens 
used to illustrate each species remains therefore about the same (6to7),but the actual number 
has been increased by 779. But as, in addition to this increase in number, many inferior speci¬ 
mens have been eliminated and better ones introduced in their stead, and a few which had been 
misnamed removed, the actual number of new specimens added has considerably exceeded this 
addition to tbe'total number. These new specimens have been selected from the various 
collections stored from time to time in the Museum ; from others purchased from Professors 
Klipstein, Krantz, &o., and from others presented by various persons or obtained in exchange, 
as well as from those collected in various parts of the country by the officers of the Survey. 
