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importance, and as we have no reason, from our knowledge of the other strata, to expect one so singu lar. We might therefore extend the general analogy, and expect to find the same series, if it should oc cur widely, following the lowest red sandstone, or at least inferior to the newer one, or to the saliferous strata. But ignorant as we are of the earth at large, and uncertain whether its greater revolutions have been all simultaneous and general, it might he dan gerous to make such a rule exclusive. Thus we must be content to wait for further information ; and at least till geologists have learnt to distinguish more accurately among the secondary strata, and to give their true places to all those deposits of coal which oc cur above the saliferous sandstone, here separated from the present series. I must only remark, that as the inferior strata are sometimes absent, and as the su perior ones are often similarly wanting where coal occurs, this series may still essentially correspond, in other countries, with that of Britain, even where the same exact order does not take place. It must remain for geologists to extend their examinations far more accurately and widely, before a satisfactory account of the subject, thus imperfectly sketched, can he produced. In an (economical light, founded on this view of the coal series, it is now proper to observe, that it must be fruitless to search for coal below the old red sandstone, and, generally speaking, beneath the moun tain limestone ; as, to mine after primary coal would he a wild project. It is almost equally useless to seek for it in those strata. It is also unadvisable to at tempt it, even in countries displaying the upper secon dary strata at the surface, where indications of coal do not exist; as it can rarely be known what the superincumbent depth is, or whether, even if that were VOL. II. x