388 Royal Society :— 
cooler latitudes condensation takes place nearer to the surface of the 
globe, and then reduction of pressure is confined to a smaller area ; 
but in parts on the surface within that area the reduction is great, 
because the lower and therefore heavier gases have been warmed and 
expanded ; hence the falls of the barometer in certain cool localities 
are the greatest. In very cold and dry regions, as a consequence of 
there being but little vapour in the air to be condensed, the barometer 
sinks only a little, and that sinking is generally confined to a small 
area. In accordance with this view, it was shown that, in certain 
places, where much continuous rain falls, the barometer has a low 
average ; and towards these areas winds blow from distant parts, as 
in the great trade- and other winds. Sea-breezes were also shown to 
be consequences of the condensation of vapour, which had been pro- 
duced by the morning sun ascending to sufficient elevations ; whilst 
the land-winds at night are attributable to the cooling of those ele- 
vated parts by evaporation during the absence of the sun. 
Various objectious that had been made to this theory of atmo- 
spheric disturbances were noticed by the author of the paper, which, 
though admitted to be plausible, were stated to be invalid, whilst the 
most important meteorological phenomena were asserted to be in 
accordance with it. 
“On the Serpentines of Canada and their associated Rocks.” By 
T. Sterry Hunt, Esq., of the Geological Survey of Canada. 
The origin and formation of serpentine is still regarded as an 
unsettled problem by chemical geologists, and Sir William Logan 
having shown from structural evidence the undoubted stratified cha- 
racter and sedimentary origin of the serpentine of the Green Moun- 
tains in Canada, I have been induced to make a chemical and mine- 
ralogical investigation of these serpentines and the rocks associated 
with them. In the present note I propose to indicate briefly some 
of the results obtained, reserving for another occasion the details of 
my examination. 
The serpentines of the Green Mountains, which have been traced 
for 150 miles in Canada, have been found by Sir William to belong 
to the upper portion of the Lower Silurian system, whose disturbance 
and metamorphism have given rise to the great Apallachian chain, 
of which the Green Mountains are the north-eastern prolongation. 
These mountains are composed of gneissoid, micaceous, argillaceous, 
taleose, and chloritic schists, with quartzite, limestone, dolomite, 
serpentine, pyroxenite, and the other rocks about to be mentioned. 
The serpentines, which form immense beds, and often cover large 
areas, are sometimes homogeneous, and at other times conglomerate 
in their character, the cement being a ferruginous dolomite, or more 
rarely a carbonate of magnesia, exempt from lime but containing 
carbonate of iron. In some cases the serpentine is intimately mixed 
with a large amount of carbonate of lime. Chromic and magnetic 
iron, ilmenite, diallage, with the ordinary lamellar and fibrous varie- 
ties, picrolite and chrysotile, are common in these serpentine rocks. 
The results of a great number of analyses show a uniformity of com- 
