376 Astronomical Society. 
which have been traced in Germany, Scotland, &e. This enor- 
mous lake, or rather insulated portion of the ocean, must have 
extended in the north, from Hudson’s Bay to below Quebec: 
the eastern boundary being the Allighany range: the western 
the diluvial hills near the Rivers St. Peter, Red, and Missouri: 
whilst the waters contained therein must have stood at 1000 
feet above the level of the sea. : 
That the fluid of this great reservoir was saline, is inferred 
from. many genera of fish, of marine origin, bemg now the in- 
habitants of the lakes; which latter are presumed to have been 
converted into fresh-water by various operations of drainage, 
&e. Large fresh-water deposits are instanced, as occurring on 
Lakes Huron and Simcoe, extending to Ontario and Erie. 
Some of the higher beds of these, in the interior, contain 
Uniones, like those of the present lakes: they are never in a 
fossil state, and are associated with Planorbes, Physa, Lymnee, 
Melania, &c. The banks of the lakes are usually constituted 
‘of several steps or terraces, which the author attributes to the 
various depressions of the waters, occasioned by excessive 
injuries to the embankments ; but with respect to the great 
primary lake, he inclines to the belief of its reduction to a 
group by one great disruption. The chaudieres, or pot-like 
cavities, are described in many situations, and the fluted’ 
chanmnellings of various rocks are further adduced, as exhibit 
ing the abrasive power of water. * 
The 3d class, or the alluvial depositions, offer nothing 
remarkable.—The 4th class, or the native debris, is derived 
from the disintegration of the subjacent, or primitive rocks. 
The Nipissing, Lake Huron, &c. offer many examples, the’ 
materials composing which appear never to have travelled far, 
but always to have been derived from the contiguous rocks, 
unaltered in their outline and angles. 
The paper concludes by the description of a limestone cave 
near New Lanark, in Upper Canada, containing bones of va~ 
rious quadrupeds, the larger of which are’ supposed to have 
been carried in by a smaller animal, and of the effects of whose 
teeth there are evident marks. 
May 19.—A paper was read, entitled, Notes on the Geo- 
logical Position of some of the Rocks of the North-East of 
Ireland; by Lieut. Portlock, Roy. Eng. F.G.S. 
ASTRONOMICAL SOCIETY. 
April 14.—At this meeting there was read “ A Comparison 
of Observations made on Double Stars.” Communicated in a 
letter to J. ¥.W. Herschel, Esq. Foreign Secretary to this So- 
ciety, by Professor Struve, of Dorpat: Addressing himself to 
Mr. 
