58 Geographical Collections. 
The other specimens teach us the following facts, which geologists may use as 
s¢ many new data :— 
1. The rare rock, which we call logite, and which is a compound of feldspar 
and hypersthene, shews itself upon a sufficiently great extent of land near Treri- 
caré, several leagues from Pondicherry, in the interior. This very ancient rock 
serves as a point of repose to tertiary sandstones, which, in this place, contain an 
immense quantity of fossil wood entirely silicified. 
2. This silicified wood, as well as all that of this part of the coast of Coroman- 
del, belongs to great stems of monocotyledonous trees,—a remarkable fact with 
respect to the actual vegetation of India. 
3. About twenty leagues to the north of Pondicherry, there exist quarries of 
a calcair grossier, often very hard, and which, by the fossil shells which it con. 
tains, would appear to characterize a deposit of nearly the same age as the Pa-« 
risian limestone. 
4, The environs of Rangoon, upon the coast of Pegu, present tertiary sand- 
stones, identical with those of the coast of Coromandel, though they are separated 
by 400 leagues of sea, which indicates that the causes which produced both the 
one and the other, were more or less general. 
Lastly, A madreporitic limestone, cellular, and very hard, containing fossil 
shells, which all belong to genera actually alive and common, occupies an im- 
mense extent of territory on the coasts of the province of Jaffnapatnam, in the 
northern part of the island of Ceylon. This limestone, which appears to belong 
to the last tertiary period, has the greatest relations with most of the ancient lime. 
stones which form a part of the islands of Oceanica. It may be said that its pre- 
sence, at the extremity of the peninsula of India, gives greater antiquity to the 
limits of the ante-diluvian portion of the madreporic crust, which is so promi- 
nent a feature in the southern hemisphere. 
Besides the series of rocks, of which we have just spoken, the officers of the 
Chevrette have brought home specimens of fresh water, taken from one of the 
branches of the Ganges, from the Irraouaddy, and from the river of Jacatra, in the 
island of Java; and specimens of several mineral waters, partly from the vicinity 
of the celebrated Pagoda of Dagon, near Rangoon, and from the environs of Trin- 
comalee, in Ceylon. The analysis of these different waters will be interesting : it 
will not perhaps be useless to verify, whether the superstitious prejudices of the 
Hindoos relative to the waters of the Ganges, may not in the origin have been sug- 
gested by some peculiarity of constitution. It will be equally curious to know 
the nature of the principles contained in the mineral waters of Trincomalee ; for 
four species of fish, and one species of turtle, live without inconvenience in these 
waters, though their temperature attains 41 degrees of the centigrade thermometer.” 
We are obliged, for want of space, to defer the report of the labours relating to 
mathematical science to our next number. 

Voyage of Caillé 
THE journey of young René Caillé, in which, alone and unprotected, he ace 
complished what, since the days of Houghton and Ledyard, has been a rock on 
which the most enterprising travellers have been wrecked, and whose journey par- 
took so much of the marvellous, that our learned countryman, Mr John Barrow, 
could not prevent a little scepticism, has excited much and universal interest. 
There can be no doubt of his having traversed the Joliba, or Niger, and of his 
having reached Tombuctoo a very short time after the death of the unfortunate 
Major Laing, and the coincidence between the name of Osman, which he applies 
‘to the chief of Tombuctoo, and an Arabian decument, containing information of 
a letter having been sent from the Sultan Ahmed-ben-Mohammed-Laboo, to his 
Zieutenant-Governor Osman, commanding him to prevent the entrance of the 
