Mineralogy and Geology. 119 
course of the Ganges lies to the Equator than the Mississippi, and con- 
sequently the enormous quantity of rain which falls in the hydrograph- 
ical basin of the Indian river. We must also attend not only to the 
number of inches which descend annually, but also to the extraordinary 
quantity which sometimes pours down ina single day in Bengal. If 
some of your numerous correspondents would ascertain the annual 
amount of rain in different parts of the valley of the Mississippi and its 
tributaries, and would publish the same in your Journal, together with 
all the facts hitherto known on the subject, they would render an ae- 
ceptable service, not merely to the meteorologist. 
5. On the Origin of the Coal of Silesia, (Proc. Brit. Assoc., from 
the Athenzeum, Sept. 19, 1846.)—Prof. Gérrert, in his elaborate essay, 
endeavored to show from the number and condition of the coal fossils, 
and the character of the strata, that the material was tranquilly depos- 
line. Its stratification is nearly horizontal, having in this neighbor 
a slight inclination to the north or northeast. Its whole thickness may 
between two and three hundred feet. The coal-bearing strata overlie 
It; below, directly upon the limestone sandy, and above 4 
unctuous clay or shale, the whole about forty feet thick On this shale 
rests a coa of three to five feet, the only workable one in this 
ighbor , covered 
by ten or fifteen feet of a blue or brown limestone, the uppermost palwozo- 
1c stratum in our region. The clay near our coal stratum is nearly des- 
titute of vegetable fossils. — 
_ The St. Louis limestone forms the uppermost bed of the carboniferous 
or mountain limestone on the Mississippi. It is divided from the lower 
beds by a sandstone formation and another thin seam of coal, which here 
out mica; it forms thick banks, and may be seen in perpendicular cliffs 
forty-five to fifty miles below St. Louis, near Prairie du Rocher in Illinois, 
where its strata show a southerly dip. In its upper part, or rather between 
it and the St. Louis limestone, occurs the lowest bed of coal. | It may be 
seen in Prairie du Long, 40 miles southeast of St. Louis, in Illinois, where 
a small stream, the Richland creek, which higher up, near Belleville, has 
denuded the workable upper coal bed and the overlying limestone, expo- 
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