i816.] Geological Society. 887 
March 1.—A letter was read from M. Coquebert Monitbert ad- 
dressed to G. B. Greenough, Esq. V.P.G.S.; in which the writer 
suggests the propriety of preserving specimens of the earthy matter 
brought up from the bottom of the sea by the sounding line, and 
of applying the knowledge thus collected to determine the sub- 
marine extent of the different strata. 
A paper by Thomas Weaver, Esq. M.R.I.A. entitled Observa~ 
tions on the distinctive Characters of the principal Classes of Rocks, 
which was commenced at the preceding meeting, was now con- 
cluded. 
Mr. W. begins his paper by controverting the Wernerian doc- 
trine of the entire absence of mechanical deposits from the class of 
primary rocks, by showing, from the writings of Saussure and Von 
Buch, that rocks of decidedly mechanical structure alternate, and 
are interstratified with clay-slate, one of the primitive rocks, and 
even with granite, gneiss, and mica-slate. He next examines, and 
denies, the validity of the arguments by which certain geologists 
have attempted to evade this difficulty, by referring all supposed 
primary rocks so circumstanced to the class of transition rocks, and 
concludes this part of his subject by maintaining, on the evidence 
adduced, that rocks exhibiting unequivocal marks of a mechanical 
structure, as breccias and conglomerates, occur, not merely in for- 
mations of a secondary nature, but also in those of primary cha- 
racter. 
In the second section of his paper, the author maintains that the 
overlying formations of porphyry, granite, sienite, and trap, which 
have been referred partly to the primary, and partly to the transition, 
class, do in fact belong to the newest floet trap formation; and 
this opinion he supports by an examination of the appearances re- 
corded by M. Von Buch in his Travels in Norway ; by Professor 
Jameson, and others, in Scotland ; by M. Giesécké, in Greenland ; 
by Mr. Humboldt, and by himself, in Ireland. 
WERNERIAN NATURAL HISTORY SOCIETY. 
At the first meeting in the present session (Nov. 25, 1815,) the 
Secretary read a short communication from Mr. Da Costa, on the 
discovery of native iron in the lead-mines of Leadhills. Specimens 
of the iron were exhibited, and an analysis by Mr. Da Costa was 
also read. 
On the same day was read a communication from Capt. Brown, 
of the Forfarshire Militia, describing several new species of shells 
found by him in Ireland. 
At the next meeting (Dec. 16,) a° model and description of a 
new rain-gage, invented by Mr. Kerr, mathematical instrument- 
maker, were laid before the Society. 
As the mouth of the common rain-gage is often projected into an 
ellipsis, and varies its area according to the inclination of the fall of 
rain; it must, therefore, be a very inaccurate instrument, ‘The 
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