228 Notices respecting New Boohs. 



Report on the Superinduced Structure of Modes, called Jointing ; and 



its relation to Slaty Cleavage. By Prof. W. King, Sc.D. fyc. 



(Trans. Royal Irish Acad. vol. xxv. pp. 605-662, with plates 



xxxiv. to xxxviii.) 4to. 1875. 



Joint-structure of rocks has necessarily commanded the attention 

 of geologists and others who deal with rock-masses, whether prac- 

 tically or theoretically, because it has to do with the mechanical 

 treatment of stone in quarries, and with the history of the rocks (as 

 a superinduced structure). The jointing of basalt, granite, coal, and 

 of various limestones and sandstones, the lamination of schists, and 

 the cleavage of slates have had, and still receive, much attention 

 from surveyors and physicists, many of whom are mentioned in the 

 first paragraph of Professor W. King's memoir. The Royal Irish 

 Academy has furthered the authors researches in this subject; and 

 his views are expressed and illustrated in this memoir under two 

 headings : — I. Jointing, its character, its extensions, its original 

 position, its dislocation, its development at different periods, its 

 origin ; and II. Its relation to slaty cleavage. 



1. Varieties of jointing and cleat, close or open, fine or rough, 

 irregular or geometrical, &c. are described. 2. The apparently 

 more or less meridional or equatorial directions and extension of 

 joints, and their original perpendicularity are insisted upon. 3. 

 The present oblique position of joints or coarse cleavage in some 

 strata lying between non-jointed beds is explained by the lateral 

 shift of such perpendicularly jointed strata. 4. The occurrence of 

 two or more sets of jointings at different angles, in successive groups 

 of strata, according to the successive jointing and occasional shift- 

 ing of some of the strata, illustrates the development of this struc- 

 ture during different periods, and accounts for the predominance 

 of some sets of joints and veins over others. 5. The origin of 

 joints is referred to as a physical phenomenon due to " divisional 

 forces akin to those which give rise to mineral cleavage ;" and, lastly, 

 slaty cleavage is said to be " essentially the result of pressure 

 exerted against divisional planes, chiefly belonging to jointing, that 

 existed in any given rock prior to its becoming affected by such 

 pressure." 



Fundamental Principles of Arctic Investigation. By Lieut. C. "Wet- 

 precht, /. M. Austrian Navy. In an Address to the Meeting of 

 German Naturalists at Gratz, Sept. 18, 1875. 

 Lieutenant Weyprecht points out the immense advantages that 

 would accrue to science and general well-being from a perfect know- 

 ledge of Terrestrial Magnetism and Meteorology, the real basis for 

 which is only to be found in regulated, continuous, and synchronous 

 observational study in circumpo]ar regions, and, for the northern he- 

 misphere, necessarily within the arctic circle. He fully appreciates 

 the value of polar investigation in astronomy and geodesy ; also the 

 importance of the polar flora and fauna, and the study of life, 

 whether migratory or fixed, under such extreme conditions ; also 

 geological phenomena and their bearings, and the interest felt ia geo- 

 graphical discovery. He regrets, however, that the race for the pole 



