70 THE GEOLOGICAL HISTORY OF THE HORSE. 
2d. That the revolution of a planetary body on its axis, and in 
its orbit round the sun as a primary body, being universal also, de* 
finite effects are thereby produced. 
3d. That these effects are, a priori, light diffused, which light 
being atomical, although immeasurably minute, the excitation of 
the atoms being greatest where the recipient body revolves most 
rapidly, or traverses the greater medium in space, namely, the 
equatorial parts ; hence it follows, as a necessary consequence, 
that the greater heat will be diffused on its central or equatorial 
zones, gradually decreasing towards both poles, where the motion 
of course is slower. 
4th. That all parts of the earth’s surface partake of the genial 
influence (so to speak) in regular successive order, requiring im- 
mense periods of time to accomplish it ; and that our planet is, 
therefore, constantly and universally progressing, with reference to 
beings existing on its surface. 
5th. That the elevation and depression of the oceanic waters in 
both hemispheres are also regular and constant, and most probably 
the effect of motion, although it may be distinct and subject to 
other laws than the changes of climate before alluded to. 
6th. From these facts the conclusion naturally follows, — that 
our planet is regularly changing its position, en masse, with refer- 
ence to the centre of the system, the sun; that is, although polar 
axes will always exist, yet that their position cannot be constant, 
but variable, producing those great changes of position, and conse- 
quently of temperature — requiring periods of time almost beyond 
our calculations, but which, by astronomical investigation, will no 
doubt ultimately be established. 
These are the principles on which Mr. Saull establishes his 
theory, and which he satisfactorily proves by examining the va- 
rious strata of the earth. Through all the primitive rocks, from 
the granite up to the clay state inclusive, no organic remains are 
found — hence their term protozoic, that is, before life; but the 
calcareous matter has gone on increasing, and in the next stage, 
in what was heretofore called granwacke, but now the upper Silu- 
rian, we find life first developed in a few varieties of shell fish 
only: other beds intervene, almost destitute of organic remains, 
succeeded by strata of great thickness, containing corals in abun- 
dance, and exhibiting, for the first time, their masses in the form 
and pattern as they grew, with trilobites, orthroceratites, leptera, 
eyathrocrinites, orphis, euomphalus, &c. & c. Abundance of other 
fossils are found in these beds, indicative of a tropical climate and 
the preponderance of saline waters. 
Above this appears the old red sandstone, in some places up- 
wards of 3000 feet thick, in which are no corals and but few fishes 
and shells, which he considers to be proof that a cold northern cli- 
