102 THE REIGN OF LAW. 



actually serving the same use. The little Bar- 

 nacles which crust the rocks at low tide, and 

 which to live there at all must be able to resist 

 the surf, have the building of their shells con- 

 structed strictly with reference to this necessity. 

 It is a structure all hollowed and chambered 

 on the plan which engineers have so lately dis- 

 covered as an arrangement of material by which 

 the power of resisting strain or pressure is multi- 

 plied in a extraordinary degree. That shell is 

 as pure a bit of mechanics as the bridge, both 

 being structures in which the same arrangement 

 is adapted to the same end. 



" Small, but a work divine; 

 Frail, but of force to withstand, 

 Year upon year, the shock 

 Of cataract seas that snap 

 The three-decker's oaken spine." * 



This is but one instance out of a number which 

 no man can count. So far as we know, no Law — 

 that is, no elementary Force — of Nature is liable 

 to change. But every Law of Nature is liable 

 to counteraction ; and the rule is, that laws are 

 habitually made to counteract each other in pre- 



* "Maud." 



