engines in England are now computed to perform annually, the work of four hundred millions of men! a number nearly double to that now living on the whole globe. Nor is the geology of the state to be disregarded. Ever since a careful examination of the materials of the earth's surface has been found to afford indications of its past changes, this science has been diligently and successfully cultivated in Europe, and has not been neglected in some parts of the United States. It is high time that Virginia should contribute her quota to its researches. We should be the more stimulated to cultivate this branch of science in the United States, in consequence of the remarkable regularity of the different formations on this continent. Thus along the coast below the falls, we have south of Long Island the tertiary formation; between the falls and the Blue Ridge, the primitive; and the great Mississippi Valley, from the Alleghany to the Rocky Mountains, if principally secondary. There are however, occasional exceptions to these general rules, and they should be noticed with care. As our useful minerals lie near the surface, our observations will, for a long time to come, be principally confined to that; but as there are instances of shafts being sunk in search of salt water or gold, the strata should be carefully noted; and where any pit of unusual depth is sunk, it would be well to make experiments on the heat of the earth, before the admission of the ordinary air has altered its temperature. It has long been asserted that there was an internal heat in the interior of the earth, and further observation seems to confirm it. This fact has lately had a seemingly conclusive verification in England. A shaft had been sunk there in pursuit of coal, to the extraordinary depth of nearly fifteen hundred feet; and by a number of careful experiments, the heat at the bottom was found to be 28° hotter than the average heat of the earth in this latitude, which would seem to show an increase at the rate of a degree of Fahrenheit for every sixty feet.[10] Should this correctly indicate the measure of the earth's internal heat, then at the depth of something less than two miles, we should come to the temperature of boiling water. When we recollect that this heat is not farther removed from us than a two thousandth part of the distance to the centre, (bearing about the same proportion to the earth as the parchment stretched over it, does to an ordinary globe,) it seems to afford a ready solution for volcanoes, earthquakes, and many geological phenomena; and may even excite our wonder, that some of these results of so mighty an agent are not more frequent and terrible than they are. And when we recollect that the confines between organized matter, and that form of it which is inconsistent with animal or vegetable life, approach so near each other, it is calculated to humble the pride of man, that he has been