662 
delight, that when Humboldt appeared among us he received the 
universal homage which is so justly his due, and which his enlight- 
ened and benevolent monarch must have been proud to acknow- 
ledge as one of the highest compliments we could offer to himself 
and to his people. 
In explaining the motives which induced the Council to award the 
medal of this year to M. von Buch, I have necessarily dwelt not 
only upon the former great services rendered by that eminent geo- 
logist, but also to his recent paleontological works. So actively 
indeed is he employed, that even whilst I write he is preparing a 
monograph on the genus Productus, thus offermg fresh evidence 
of his sagacity and indefatigable research. 
Ehrenberg, to whom I have elsewhere alluded, is daily adding to 
his conquests over the invisible realms of nature, and Gustaf Rose has 
written on the metamorphism and mineral structure of the Ural 
with so much ability, that it will be my special business to dwell at 
some length on this topic on another occasion. 
In the construction of improved geological maps of various parts 
of the Prussian dominions, Professor von Dechen still pursues his 
useful and meritorious career. His large and detailed map of the 
Rhenish provinces, in-which he has been aided by Erbreich and 
other good geologists of the Prussian school of mines, is I be- 
lieve completed. Two years ago M. von Dechen kindly furnished 
me with an unfinished copy, which has served as the model, from 
which has been taken the small map prepared for the Transac- 
tions to illustrate the memoir on the Rhenish provinces by Professor 
Sedgwick and myself. You must not, however, Gentlemen, judge 
of the very high merits of the original from the reduced skeleton 
map which we publish, and I beg you to consult the former as one 
of the most valuable documents of this nature yet offered to. the 
public, particularly in the elaborate delineation of every variety of 
igneous, metalliferous, and metamorphic rocks, in a region so stri- 
kingly replete with them. Silesia has also occupied much of the time ~ 
of M. von Dechen, in some districts of which he has marked the 
existence of bands of carboniferous limestone as distinguished from 
the Devonian, Silurian, and older members of the paleozoic series. 
Oeynhausen, the old associate of Von Dechen, and so well remem- 
bered by many of us, has recently bored in search ef salt springs 
through upwards of 1000 feet of lias near Pyrmont, a fact which 
ought to teach us great caution in estimating what may be the 
maximum thickness of deposits. In our own country, the accu- 
rate method which Mr. De la Beche employs to test the thick- 
ness of deposits, will eventually give us, I trust, close approxima- 
tions to the facts; and I learn from him that some of the ancient 
strata (the carbonilerous for example) which have been aceumu- 
lated in basins are enormously more thick than we had supposed, 
whilst others extending, like the Old Red Sandstone, over wide 
areas in lofty escarpments, will not prove to have those dimensions 
we had assigned to them. When, indeed, we consider that all 
shales, sandstones, &e. were once nothing more than the blue and 
