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to explain the origin of these formations; and, that further diligent 

 research, astronomically and otherwise, will bring to view more rational 

 conclusions as to the causes of these phenomena." The author next 

 proceeds to illustrate the practical uses of Mr. Smith's discovery — that 

 every stratum has its own peculiar fossil ; and to shew that, by observing 

 the particular fossil plants in the several strata, the miner is enabled to 

 trace the height or depth to which the dislocated measures may have 

 passed. Many of the alternating seams are so nearly alike in structure, 

 colour, and density, as to be scarcely distinguishable j but the fossil 

 plants or impressions, wherever they can be seen and examined care- 

 fully, indicate the particular stratum to which they belong ; so that, upon 

 finding a slip, although the hading might show whether the coal was 

 gone up or down, the distance could not be known : but, by driving an adit 

 in a right line through the slip, the regular measures are arrived at ; and, 

 upon proceeding a little way in them, it is soon ascertained to what 

 height or depth the seam of coal has slipped ; either by the decided 

 character of the stratum itself in which the adit is driven ; or, more 

 certainly, by the peculiar fossil impressions it contains. In speaking of 

 the fossiliferous measure, the author introduces the remarks — that " the 

 alternating beds which are liable to quick decomposition, do not retain 

 their impressions many days, particularly the delicate ones, unless covered 

 with varnish and protected from the atmosphere or water : in the sand- 

 stone beds, the impressions continue longer. The larger kinds of fossil 

 plants are much better preserved, as their interior is generally of the 

 same substance as the matrix in which they are imbedded, and they are 

 not so flattened as the same description of plants in the bind. Whether 

 in the stone, however, or in the bind, or in any stratum whatever, the 

 bark with all its minute tubercles, or forms, is preserved entire ; and 

 this bark, whether its thickness be one inch, or one-thousandth part of 

 an inch, is coal.*' Attached to this chapter, and its valuable inductions, 

 is an elaborate foot-note, p. 65, intended to shew "how deficient the 

 information is, from which the geologist can form just notions of the 

 constitution of the earth ; and that the inquiry must be pursued with 

 diligence and accurate delineations in all countries, until a mass of 

 evidence be brought together that shall establish a theory less liable 

 to objection than any yet established." Entertaining precisely the 

 same sentiments, we advise our readers to " pursue the inquiry;" and, 

 in their practical or experimental investigations, to profit by the multi- 

 tude of determinate principles, so graphically communicated in Mr. 

 Mammatt's ** Facts and Observations.'* 



Chap. X. — Not a few very curious facts are stated in this chapter, 

 which is entitled, ** On Ironstone, and its Existence in almost every 

 Stratum of this Field ; and on Fire-clay, with its uses." Ironstone 

 abounds in the alternating beds of clay, clunch, bind, and stony bind, 

 but rarely in the grit or sandstone : occasionally, it has a regular course 

 for some square miles in particular strata, about two inches thick ; in 

 others, it is divided into rounded portions varying in size, with a space 

 some inches between them. Generally, these portions, as well as their 

 layers, are solid, and shew few vegetable impressions. In other measures, 

 the ironstone is conglomerated, and consists of nodules not larger than 

 walnuts; but, where it is richest 'and most abundant, the nodules have 

 the size of potatoes, and often contain vegetable impressions. Others, 

 with a smooth compact exterior, are full of cracks within ; these are 

 wide at the centre of a nodule, but close before they reach its outside ; 

 sometimes they are empty, sometimes filled with lime or crystal of lime, 

 occasionally with water, which is very salt ; and they all appear to have 



