PETROLEUM. 
59 
do with the formation of iron as they did with the 
production of coal. In boggy places I have often 
seen rusty sediment; sometimes this sediment had 
hardened into “ bog-iron.” In all geological ages 
there are rocks colored brown or red by the iron in 
them, but in the neighborhood of iron beds there are 
no such colored rocks. It would seem, then, that in 
some way, by means of water, plants leached the iron 
out of the rocks, and that water carried it down into 
low, swampy places, where it settled on clay beds and 
formed iron ore. 
There is here a wise provision which looks for¬ 
ward to the time when man discovers the iron and 
makes it contribute to his civilization. The nearness 
of coal to iron enables man to smelt the ore at the 
lowest possible cost. The rapid industrial develop¬ 
ment of the western part of England is due to the 
coal and iron beds which are found there side by side. 
PETROLEUM. 
In many parts of the world spring-water has been 
found covered with a film of oil. Some springs con¬ 
tained a large proportion of oil. Such a spring was 
discovered near Titusville, Pa. Accordingly a com¬ 
pany was organized, and a well sunk in 1859, which 
reached oil at a depth of thirty-five feet. Since then 
many other wells have been bored, not only in that 
State but in many other parts of the world ; and the 
total output has increased to 155,000,000 barrels an¬ 
nually. From some of these wells the flow was very 
great. Some in Ohio yielded 5,000 barrels a day, 
