r 
Geology and Mineralogy. 151 
of Vienna the mean height of the Continent is 296°838 meters, 
instead of 205 meters as made by Humboldt. The mean heights 
of the several countries are also given in the “‘ Revue de Géologie.” 
Temperature of the Earth’s crust.—According to M. Ludovic 
Ville, a deep boring in Algeria, west of Sebkha d’Oran, the 
temperature of 49°-7 C. was reached at a depth of 578 meters, 
making the mean increase downward 1° for 7°56 meters. The 
place, according to M. Ville, was 1° C. for 23 meters of descent. In 
the Sahara toward the latitude of Oued Rhir, the increase down- 
ward is about 1° for 17°55 meters; showing a diminution toward 
the south, or with the latitude. 
iffect ‘of moisture or dryness in rocks on the facility of 
crushing. —M. Tournaire, Mining Engineer and M. Michelot have 
experimented on chalk, dried in a stove (d), wet (¢), and air-dried 
te and found that cubes 3 decimeters each way, were crushed, as 
ollows:—when stove-dried it was crushed under 80-925 kilo- 
grams (mean 86:2); when air-dried, 16°5 to 35 (mean n 
wet, 13°9 to 26 (mean 18°6). lesse gives also the results of 
ious experiments of his own on ¢ and the Calcaire 
of Issy, ee stove dried, Bie crushed with 36°4 kilograms; when 
air-dried, 23°6; when wet, 12°9; and the Calcaire Grossier of 
trials with the Caleaire Grossier are given, all confirming the 
en result here exhibite 
13. Mémoires sur a“ Terrains Crétacés et Tertiares, préparé 
bar feu Anprk& Dumont, edités Micuet Movrton, Conserva- 
teur au Musée Royals + "Histoire Naturelle. Tome 1. Zerrains 
Crétacés, 556 pp. 8vo. Brussels, 1878.—The late M. Dumont, 
the distinguished Belgian geologist, prepared in 1849 a geological 
map of Belgium. He died in 1857, tarts forty-eight years old, 
leaving his Reports illustrating the subject in part still i shores 
Script, and other unfinished work. The Belgian government has 
Tecently ordered a new edition of the map, and also the onbliage 
issued. It is a very valuable contribution to European geology. 
Hees Sigillaria | lepidodendrifot ia a Brgt.—Mr. H. L. Farrcuixp, 
Scie ea (vol. i, no. 5), gives reasons for believing that the Sigil- 
> sa ‘rhomboid (with S. obligua), S. Brardii, 8S. Menardi, 8. 
ancit of Bronguiaet and 8. seulpta of Aen 
a use Taontica species with S, lepidodendrifolia, and adds that 
