10 GEOLOGY APPLIED TO CIVIL ENGINEERING. 



GEOLOGY APPLIED TO CIYIL ENGINEERING. At the 

 present day, when nearly the whole of the British Isles is 

 being intersected with railroads, a knowledge of the general 

 principles of the geology and physical geography of the 

 region which is to be the sphere of the undertaking, are 

 highly important to the engineer. The nature and composi- 

 tion of the different strata, varying as they do from loosely 

 coherent beds of gravel, sand, or clay, to rocks of crystalline 

 structure, will often determine the choice to be pursued in a 

 given district : for example, when the beds are loose and 

 porous, they are frequently to be avoided; while a rock, 

 though hard and crystalline, may present a valuable stone 

 for masonry, and repay the cost of penetrating. As regards 

 the construction of these and other public works, an 

 acquaintance with geology is found to be of such essential 

 importance, that it now constitutes a part of the education of 

 the engineer. 



CONNEXION OF GEOLOGY WITH AGRICULTURE. The 

 agriculturist is benefited by that insight into the struc- 

 ture of the globe which geology unfolds ; as the super- 

 ficial soil is usually derived from the disintegration of the 

 adjacent rocks, an acquaintance with the nature and chemical 

 composition of strata is of utility in pointing out the best 

 mode of cultivation. Those lands are most productive, and 

 least liable to exhaustion, which contain a due admixture of 

 clay, flint, and lime ; but as instances are few in which 

 nature has bestowed them in proportions best adapted for a 

 productive soil for the growth of the cerealia, it is the study 

 of the scientific agriculturist, by a rotation of crops, a mixture 

 of manures, and by adding the deficient mineral body, to 

 produce, by science, what nature has withheld. 



In the all-important operation of drainage a knowledge of 

 the strata of a district is of the first importance. 



ARTESIAN WELLS. A knowledge of geology enables the 

 engineer to obtain a copious supply of water under peculiar 

 conditions of certain districts by Artesian "Wells, so called 

 from their having been first introduced in the province of 

 Artois, the ancient Artesium, in France. These wells have 

 been so frequently brought before the notice of the public, 

 that the simplest outline will suflice to convey an idea of 

 the principle of their construction. The annexed diagram 



