HUTTONIAN THEORY.

153

beds, the coal having been worked only at oneplace, and bv an open pit, without any extenfivefubterraneous excavation, nothing is known withcertainty.

In the Bovey coal too, I mull obferve, thoughits beds have the ligneous ftru&ure very diftind,the clay interpofed between thefe beds, whichis but little indurated, contains a great deal ofcoaly matter, in the form of thin Hakes, mter-fperfed through it. So far as I know, there areno mineral veins nor drifts, nor any bed of in-durated ftone, that accompany this coal •, fo that,though one cannot doubt of its vegetable origin,feme doubt may be entertained concerningthe nature of the mineralizing operations, towhich it has been fubjeCted. The coniiderationof thefe, however, does not belong to the prefentargument; and the peculiarities of this femi-mineralized coal, as it may be called, havenothing to do with the general queltion, whe-ther wood-coal and mineral-coal are the famefubftance ; about which queftion, if the grada-tions are properly confidered, I think, no rea-fonable doubt can remain.

141. One of Mr Kirwan’s objections to thevegetable origin of coal, is founded on this fact,that there is, in the mufeum at Fi >rence, a cel-lular fandftone. the cells of which are filled withgenuine mineral coal. “ Could this, (adds he)

have