28 
Performance of the Dence. 
[Jan. 
clay ; when examined more carefully, it is evident that this appearance is owing to 
a peculiar modification of the concretionary structure, developed by decomposition. 
Nuclei, of various sizes, are enveloped by concentric lamella?, which peel off as de- 
composition destroys their cohesion. They are consequently seen in various states 
of decay, and of sizes, varying from several feet in diameter to several inches. But 
their true nature is easily discovered by the mutual indentation of the different la- 
mellae, which surround their respective nuclei, the centres from which this pseudo- 
crystallization has proceeded. The existence of the vertical and waved fissures 
need scarcely be adduced as farther proof that they are not the product of alluvial 
detritus. 
It appears most probable that they owe their forms to molecular magnetic attrac- 
tion, since they contain a very large proportion of oxide of iron, (nearly twenty-five 
per cent.) as may be perceived by the great specific gravity of band specimens. 
The nodular wacken or basalt, is one of the most common forms of trap in the 
extensive districts, composed of tbe rocks of this family, south of the Nermada. 
It occurs perpetually in the extensive and lofty range of mountains situated be- 
tween thePurnea and Tapti rivers, and appears to form their principal mass. It is 
found equally abundant throughout the whole of Berar, part of tbe provinces of Hy- 
derabad, Beder, and Sholapur, and appears to form the basis of the great western 
range of trap hills, which separate the Kenkan from the interior of the Dekhin. 
It is probably one of the main sources, when decomposed, of the black diluvial 
soil to which Hindoostan owes so much of its fertility. The valley or extended 
plain of Berar, that of Hasanabad, of Seronj, of Nandiala, south of Krishna, of the 
Palnad, bordering the Krishna, and numerous others, all lie near the course of ri- 
vers, which at some former period have covered these plains and formed their ex- 
tensive deposits of alluvium. Whether the deposition originated in some sudden 
and partial inundation, or whether it was owing to the gradual subsidence of the 
waters of the great deluge, I think may be determined by cautious investigation. 
I am at present inclined to think that the most probable cause was the latter. 
The hill of Sitabaldi offers favorable opportunities, if the quarries are extended, 
of ascertaining positively whether the basalt is merely a superficial deposit, or is 
deeply connected with a mass beneath. It is surrounded on all sides bv gneiss or 
slaty granite, which is found at the base of the hill a few feet deep. Perhaps Nag- 
pur affords more opportunities than any other part of India, of studying the geolo^m 
cal history of these rocRs, as it is situated near the junction of the primary and over- 
lying rocks. Numerous opportunities must arise during the excavation of wells 
and baths, of ascertaining the connexion of the strata beneath. A well in Mr Alex. 
Gordon s garden, near the base of the hill, of about forty feet depth penetrates 
through three or four feet of black soil, succeeded by a magnesian si ’ 
which appears to owe its origin to the decomposition of the gneiss bv 
immediately followed, and which continues to the bottom of the well * 
„Jt r ° m i the SUmmlt ° f tl ?f, hiU of Sitabaldi the difference in the outline of the rocks 
fiattCn t efl SU r‘ itS and lot * «at outl?ne With t 
g - P * the trap lulls, are exchanged for the ridgy, peaked sh irn out- 
line of the primary rocks. At Ramtek and its vicinitv the I’ slu, P> out 
gneiss. At Dungari, at Palora and ParSmi are found cr y'umlT ° JP™* ^ 
into gneiss, capable of receiving a fine nolisl • tnnTTtf U lzed . tnarb,es P ass,n ? 
tity of carbonate of magnesia. At Khorari a dolomite ‘n Contam a . sma ** < l aan ' 
found, also in gneiss. At Nayakund, Parshni ’and 'the bed of T' "- n marble ‘ S 
and gneiss of various kinds, also quartz rock . i l l! , 1 esh nver > gramt f 
manganese ore is in great quantity 1 * ’ d sandbtone i and foliated black 
liceous 
which 
clay, 
it is 
Sir, 
IX.— 0,» the Quantity of \Vuter raised by the Deuce. 
To the Editor of the Gleanings in Science. 
It is with much gratification that I have seen , i 
correspondents devoted to the most effir tn* ° SC “ uch of the Mention of vo 
the fertility „f the valley of tl “oa^es ' ° t ““ ° water > believing tli 
tion to an extent beyond present Credibility Y The ^ ! m P rovc, »«m» Irn ? 
improvement is to settle the value of tl,n 7 ' , ie point, however, towards ai 
tives for raising water, and 1 haVe nlen« In ° P ^ n . ,a ^ unes now employed by then 
the enclosed extracts from the observation 16 J” )ein ^ able to communicate to yi 
and Behar on the comparative merits of'iT -°1 .!• ^ ent 1 eman during a tour in Pat 
consider as in general much underrated 1 vv ! cr awl ^ The former I shou 
unaei rated. When water is to be raised from she 
