390 Tlie American Geologist June, isqo 
and to lead them to join him in drilling for a larger supply. In March 
1883 Dr. Oesterlin organized the Findlay Natural Gas Co. with a capi- 
tal stock of $5,000. The drilling of the Pioneer well developed several 
minor gas horizons but at 1,092 feet a horizon of solid highly crystalline 
limestone was reached, which proved a reservoir of high-pressure gas. 
The gas was lighted, and its blaze at night illuminated a circle of coun- 
try 20 miles in diameter. The Pioneer well was successful. A new 
horizon of gas and oil, not dreamed of before, was brought to light and 
Findlay became the centre of inspiration of development of fossil power 
scarcely, if at all, inferior in value to the great petroleum reservoirs of 
western Pennsylvania and New York. The flow from this first well is 
estimated at 300,000 cubic feet per day. This much we condense from 
the account of the development of the new field. 
The fourth chapter embraces the discussion of the geological ele- 
ments in the problem. Incidentally this chapter illustrates the short- 
sighted policy of legislative action in aiding only what is speciously 
termed practical geology and discriminating against paleontology* 
Even the most minute fossils may have an important practical bearing. 
Excellent specimens of the almost microscopic shell Leptobolus insignis 
H. were brought up in fragments of shale from a depth of 1,200 feet 
and positively locate the horizon of the Utica slate. The fact that fos- 
sils are the only indubitable indices of the age of a rock cannot be too 
often reiterated. Attention is called to the petroliferous character of 
the Clinton which may yet acquire as great importance in the North 
as an oil-bearer as in the South as a source of iron. 
As open to criticism we note the use of the term "Devonian shale' 
to include the Cleveland, Erie, and Huron shales. Prof. Orton states 
that "the belief that the great shale system would everywhere admit 
of the convenient and easily-applied system of division above stated 
has not proved well-founded." On the other hand Dr. Newberry forci- 
bly claims that these three shales have nothing in common and Prof. 
C L. Herrick has sought to indicate the nature of the conditions which 
locally combined elements of them all and interblended them in places 
with horizons of Hamilton habitus. 
A very interesting generalization is stated in the concluding chapter 
viz., that the porous character of the limestone in the petroliferous 
district is due to a process of dolomitization which resulted in complete 
crystallization leaving interstitial pores and spaces capable of carrying 
large quantities of oil, gas, or water. This dolomitization of the Tren- 
ton limestone seems to have been in the main regional and confined to 
the upper portions of the limestone. A warping of the formation has 
resulted in the differentiation of the contents of the porous portions, 
the gas and oils seeking the highest levels and the salt water remain- 
ing at a lower but definite elevation in every field. Prof. Orton con- 
cludes "it is unsafe to count the Trenton limestone an oil rock or a gas 
rock in any locality unless it can be shown to have undergone the dol- 
omitic replacement by which its porosity is assured. Even in case it has 
