EXPLANATION OF THE FIGURES.

Since the brevity of a hurried composition has left not a few things less clearly explained, especially where angular bodies and the strata of the earth are concerned, I have decided to append here the following figures, selected from many others, to apply some sort of remedy to this defect.

The thirteen preceding figures, intended for the explanation of angular crystal bodies, are reduced to two classes.

The first class contains seven differences of the plane in which the axis of the crystal lies. In figures 1, 2, and 3, the axes of the parts from which the crystal body is composed form a single straight line, but the intermediate column, which is missing in the first figure, appears shorter in the second and longer in the third. In the fourth figure, the axes of the parts constituting the crystal body do not form a single straight line. The fifth and sixth figures are of the kind that I could have claimed to be infinite, in order to prove that in the plane of the axis, the number and length of the sides can be varied without changing the angles, and that various cavities can be left in the crystal itself, and various lamellae thin plates or layers can be formed. The seventh figure indicates in the plane of the axis how, through new crystalline matter added upon the planes of the pyramids, the number and length of the sides are variously increased or decreased.

The second class contains six differences of the plane of the base. In figures 8, 9, 10, and 11, only six sides are counted, yet with the difference that in figure 8 all sides are equal; in figures 9 and 11, not all sides, but only the opposite ones are equal; in figure 10, however, any opposite sides are unequal. In the twelfth figure, the plane of the base, which should be a hexagonum hexagon, is contained by twelve sides. The thirteenth figure indicates how, while new crystalline matter is imposed on the planes of the pyramids, the length and number of the sides in the plane of the base are sometimes varied without changing the angles.

The six following figures explain two different types of angular iron bodies. Figures 14, 15, and 16 serve to explain those angular iron bodies which are comprised of twelve planes: figure 14 shows all those twelve planes unfolded into a single plane, of which six are triangular and polished, and the remaining six are pentagonal and striated. Figure 15 is the plane of the base of the same body. Figure 16 is the plane of the axis of the same body.

Figures 17, 18, and 19 serve to explain those angular iron bodies which are comprised of 30 planes; figure 17 shows all those 30 planes unfolded into a single plane, of which 6 are pentagonal and polished, 12 are triangular and likewise polished, 6 are triangular and striated, and 6 are oblong quadrilaterals and polished. Figure 18 is the plane of the base of the same body; figure 19 is the plane of the axis of the same body.

The last six figures, while indicating how we deduce six distinct phases of Etruria from the present face of Etruria, simultaneously serve to explain more easily those things which we have said about the strata of the earth. Lines marked with dots represent sandy strata of the earth, so named from the more prevalent material, even though various clay and stony strata are mixed in with them. The remaining lines represent stony strata, likewise so named from the more prevalent material, since sometimes there are other strata of a softer substance situated between them. In the Dissertation itself, I have explained the letters of the figures, in the order in which the figures follow one another; here I will briefly recount the order of change. Figure 25 shows a perpendicular plane of Etruria at the time when the stony strata were still intact and parallel to the horizon. Figure 24 shows huge cavities, hollowed out by the force of either fires or waters, with the upper strata left intact. Figure 23 shows mountains and valleys arisen from the disrupted upper strata. Figure 22 shows new strata made by the sea in said valleys. Figure 21 shows a portion of the lower strata consumed from the new strata, while the upper ones remained intact. Figure 20 shows hills and valleys produced there after the upper sandy strata were disrupted.

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