124 An Essay on Rents. (Fes. 
parts which differ from one another in appearance; and the essen- 
ally differmg paris ave arranged into completely concentric layers. 
That the concrete earthy matter is a great and universally conti- 
nuous mass, I will now endeavour to show. The visible parts of 
this matter are generally situated on the highest parts of the dr 
land; ona lower level, the concrete lime-stone puts on; and below 
it the stratified matter commences. Were we to draw a sectional 
line through a large visible part of this matter, in any direction 
except the longitudinal one, the centre of the part would be the 
highest point, and from this place the line would bend downwards 
in a regular and easy curve, till either the lime-stone or the strati- 
fied formations were met with; and if the former, the line would 
still descend, but easier than before, till it reached the stratified 
formations ; it would then incline a little, but would be nearly 
horizontal: if we pursued this line straight ferward, it would, 
ascend easily the contrary way, while it passed through the stratified 
ground; then steeper over the concreted lime-stone; and still 
steeper over the concrete earthy matter, to the summit of the 
ground. After observing this line again descend for a certain dis- 
tance, it would re-ascend ; thus passing over a visible portion of 
earth-stone; then over the lime-stone, or the stratified formations, 
or both; and then over another part of the earth-stone; and so on 
alternately. When we observe the curve of the earth-stone, and 
examine how the lime-stone and stratified matter put on, we at 
once give the negative to the idea that the earth-stone terminates 
where the lime-stone or stratified matter commences, and conclude 
that it continues under them ; and as a proof that this conclusion 
is just, we actually find some of the earth-stone’s great eminences 
reaching above them. Again, when we have traced the descending 
part of a series of stratified formations, and meet with another 
elevated part of the earth-stone, it appears as if it rose from under 
the stratified formations near it; in other words, its surface inclines 
to the other portion in such a way as to show that these portions are 
only the visible parts of the same mass. Hence we may infer that 
the earth-stene is an universally continuous mass that exists every 
where in low as well as in high situations; of course it envelopes 
the inner part of the earth, and contains in its surface-hollows the 
lime-stone and stratified matter. 
The earth-stone is divisible into parts which differ in externa. 
characters. . Such parts, however, are firmly united together. The 
parts that differ essentially from one another are arranged in con- 
centric layers. There are two layers exposed at the surface, and 
found in mines. The lower layer is granulated, or grained, and 
consists of granite, sienite, &c.; the upper layer is compact, and 
is composed of clay-slate, mica-slate, &c. The concentric arrange- 
ment of these layers will be evident from what follows. In every 
extensive part of the earth-stone we find at least one variety of 
grained earth-stone. Now if we make observations on the shape 
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