geognostic phenomena indicate a periodical alteration of activity in the
interior of our planet. Probability of new elevations of ridges -- p.
293-301 and notes.

g. The solid surface of the earth has two envelopes, one liquid, and the
other aeriform. Contrasts and analogies which these envelopes -- the sea
and the atmosphere -- present in their conditions of aggregation and
electricity, and in their relations of currents and temperature. Depths of
the ocean and of the atmosphere, the shoals of which constitute our
highlands and mountain chains. The degree of heat at the surface of the sea
in different latitudes and in the lower strata. Tendency of the sea to
maintain the temperature of the surface in the strata nearest to the
atmosphere, in consequence of the mobility of its particles and the
alteration in its density. Maximum of the density of salt water. Position
of the zones of the hottest water, and of those having the greatest saline
contents. Thermic influence of the lower polar current and the counter
currents in the straits of the sea -- p. 302-304 and notes. General level
of the sea, and permanent local disturbances of equilibrium; the periodic
disturbances manifested as tides. Oceanic currents; the equatorial or
rotation current, the Atlantic warm Gulf Stream, and the further impulse
which it receives; the cold Peruvian stream in the eastern portion of the
Pacific Ocean of the southern zone. Temperature of shoals. The universal
diffusion of life in the ocean. Influence of the small submarine sylvan
region at the bottom of beds of rooted algae, or on far-extending floating
layers of fucus -- p. 302-311 and notes.

h. The gaseous envelope of our planet, the atmosphere. Chemical
composition of the atmosphere, its transparency, its polarization, pressure,
temperature, humidity, and electric tension. Relation of oxygen to
nitrogen; amount of carbonic acid; carbureted hydrogen; ammoniacal vapors.