Miscellanies. 397 
23. Mean Height of the Continents above the Surface of the Sea; 
by Baron von Humsotpr.—Since immense and lofty chains of moun- 
tains occupy our imaginations, by presenting themselves as evidences of 
vast terrestrial revolutions, as the boundaries of climates, as great water- 
sheds, or as the bearers of different vegetable worlds; it becomes so 
much the more necessary to show, by a correct numerical estimate of 
their volume,’ how small the whole quantity of the elevated masses is in 
comparison with the area of entire countries. The mass of the Pyrenees, 
for example—a chain, the mean height of whose summits, and the su- 
perficial extent of whose base, are known by accurate measurements— 
would, if distributed over the area of France, increase the height of that 
country only 115 English feet. ‘The mass of the eastern and western 
chains of the Alps would, in the same manner, raise the height of the 
flat country of Europe by only 21°3 English feet. By means of a labo- 
rious investigation, which, from its very nature, only gives the upper limit, 
i. e. a number which may be smaller, but cannot be larger, I have ascer- 
tained that the centre of gravity of the volume of the land which rises 
above the present level of the sea, is situated at a height of 671 and 748 
English feet in Europe and North America, and 1131°8 and 1151 Eng- 
lish feet in Asia and South America.* These calculations indicate the 
lowness of the northern regions; the great steppes of the plains of Sibe- 
ria are counterbalanced by the enormous swellings of the surface of Asia 
between lat. 283° and 40°, between the Himalaya, the northern Thibe- 
tian Kuen-Lun, and the Sky Mountains. We can, to a certain extent, 
determine, from the estimated amounts, where the plutonic force of the 
interior of the globe has operated with greatest power in elevating con- 
tinental masses. The mean height of the non-mountainous portion of 
France does not exceed 512 English feet.—Jameson’s Jour., July, 1845. 
24. Infusoria.—Ehrenberg has examined various tufas and other beds 
in volcanic regions, and finds that they often consist largely of infusoria. 
His investigations were made upon specimens from Patagonia, Ascen- 
sion Island, the Rhine, Pompeu, Mexico, Chili, and other regions, and 
he shows their connection with the formation of opal and other siliceous 
deposits. The tufaceous rocks of the Hochsimmer volcanic hill, near the 
Laacher-Sea, contains the infusoria in a ‘roasted’ condition, and of thirty 
eight species found, only two were new. 
Ehrenberg proposes to distinguish rocks without infusoria by the gen- 
eral term Stechiolitic, alluding to their pure or simple character; but 
when they contain infusoria, they are styled Hydrobiolitic :—or if connect- 
* The corresponding amount for the whole globe will consequently be some- 
what less than 1000 feet. 
Vol. xu1x, No. 2.—July-Sept. 1845. 51 
