80 M. Keilhau's Theory of Granite and other Rocks, 



torn from the quarry, and fashioned into this splendid town, is 

 minute indeed, yet, undoubtedly, that transference has retard- 

 ed the rotation of the earth, although our senses, aided by 

 every contrivance of science and of art, be utterly unable to 

 discern a trace of the change. 



While, then, we zealously strive to improve our machines, 

 and to remove the friction from the inefficient to be concentra- 

 ted on the working parts, let us not repine that, after all our 

 exertions, we are still compelled to resign a tithe of our labour 

 to that influence under which alone it is possible for us or our 

 machines to exist; and let us console ourselves with the thought, 

 that, though our exertions be lost to us, nature has taken care 

 that they conduce to the maintenance and well-being of the 

 general system. 



Theory of Granite^ and the other Massive Rocks, together with 

 that of Crystalline Slate; pr-oposed in Lectures on Geology <i 

 in the University of Christiania in Norway, in the year 

 1836. By B. M. Keilhau, Professor of Mineralogy. 

 (Continued from Vol. XXIV. p. 403.) 



At several points on the boundaries of the great granite and 

 porphyry districts, it happens that granite and syenite on the 

 one side, and porphyry on the other, pass completely into each 

 other. Further, we find also in some places gradual changes 

 from the granite to the clay-slate. Moreover, we see the same 

 from granite to the primary gneiss, and also many other tran- 

 sitions. We shall here bring forward only some of the most 

 important. 



The boundaries between the porphyry and the granite dis- 

 tricts exhibit sometimes a confused intermixture of the respec- 

 tive masses, and sometimes true transitions ; the latter proceed 

 quite step by step, so that we pass perhaps for a distance of 

 two miles (more than one-fourth of a Norwegian mile) over a 

 rock intermediate between granite and porphyry, before we 

 reach the clearly exhibited type of the one from the distinct 

 type of the other. If the opinion be adopted, that the massive 



