Theory of the Earth

THE fact to be proved with regard to these iron-stones is this, That they have acquired their solid state from fusion, and not in concreting from any aqueous solution.

TO abridge this disquisition, no argument is to be taken from contingent circumstances, (which, however, are often found here as well as in the case of marbles); such only are to be employed as are general to the subject, and arise necessarily from the nature of the operation.

IT will be proper to describe a species of these stones, which is remarkably regular in its form. It is that found at Aberlady in East Lothian.

THE form of these iron-stones is that of an oblate or much compressed sphere, and the size from two or three inches diameter to more than a foot. In the circular or horizontal section, they present the most elegant septarium *; and, from the examination of this particular structure, the following conclusions may be drawn.

First, THAT the septa have been formed by the uniform contraction of the internal parts of the stone, the volume of the central parts diminishing more than that of the circumference; by this means, the separations of the stone diminish, in a progression from the centre towards the circumference.

2d, THAT there are only two ways in which the septa must have received the spar with which they are filled, more or less, either, first, By insinuation into the cavity of the septa after these were formed; or, 2dly, By separation from the substance of the stone, at the same time that the septa were forming.

WERE the first supposition true, appearances would be observable, shewing that the sparry substance had been admitted, either through the porous structure of the stone, or through proper apertures communicating from without. Now, if either one or other of these had been the case, and that the stone had been consolidated from no other cause than concretion from a

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