Page:A Treatise on Geology, volume 2.djvu/345

 CHAP. XI. and gritstone have perished in churches and houses in less than 100 years. The reason is, that the different beds of a rock are of very unequal value, and here the geologist or scientific mason will have their claim to attention.

As certain trees will bear the ocean air even in our unfavourable climate and others not, so with stone; it is not equally durable in all situations, but yields variously and unequally to carbonic acid, smoke, dampness, and salt vapours. Most wisely, therefore, has a commission been issued to determine, in the case of the new houses of parliament, the best material for this national work, and we trust that this symptom of reviving attention to the importance of scientific advice in guiding the skill of our workmen, may be the harbinger of a more frequent reference of questions unsuited for the decision of statesmen, to those persons who have, by a life of study, qualified themselves to give opinions useful to their country.

Two things have been established by geological research in opposition to the contracted "experience" of colliers, and it is difficult to say which is most important. First, it is perfectly ascertained that coal is limited in Europe and America, almost absolutely, to one portion of the series of strata. Secondly, it is demonstrated, that coal occurs in abundance and of excellent quality beneath large tracts of country where few or no indications of its existence appear at the surface. In the practical working of coal which has been discovered, geological principles may often be useful in determining its probable extent, but their main value is in the discovery of coal in new situations, and the arresting of costly and fruitless trials for coal, where it cannot be found.

In both of these points of view, geology appears in that favourable light when, compared with mere "