56 Mr HOPKINS, ON RESEARCHES IN PHYSICAL GEOLOGY. 



the manner I have indicated,) will be still parallel to this axis (in the 

 sense in which one curve line may be said to be parallel to another) 

 and every fissure of the transverse system will be perpendicular to 

 each fissure of the former system at the points of their intersections, 

 and consequently the fissures in this transverse system will not be 

 parallel. Again, if we suppose the superficies of our elevated mass 

 to be of finite length, and to be bounded for instance by a line 

 approximating to the form of an elongated ellipse, the directions of 

 the fissures in the transverse system, as we approach towards either 

 extremity of the elevated range, will gradually change from perpen- 

 dicularity with the major axis (the axis of elevation) till they become 

 parallel to it, at the extremities of the ellipse, always preserving their ap- 

 proximate coincidence with the directions of the lines of greatest incli- 

 nation of the general surface of the mass. The fissures of the other 

 system wiU be approximately perpendicular to these lines. In this case 

 then, the two sj'stems will be no longer characterized by any constant 

 relations which their directions bear to that of the axis of elevation, 

 and therefore the terms longifud'mal and transverse will cease to desig- 

 nate them so correctly as in other cases; and still more is this the 

 case, where the elevation approximates to the conical form, in which all 

 the fissures analogous to those we have termed transverse, diverge from 

 the vertex of the cone. I have not, however, thought it necessary to 

 supersede these terms by others, since they are very generally applicable 

 with great propriety. It is highly important, however, as respects the 

 application of this theory of elevation, to distinguish these two systems 

 carefully from each other. It has been pointed out (Art. 56) how much 

 the transverse fissures exceed the others in regularity of formation, and 

 it seems not improbable, that this fact may be in some way connected 

 with that of their containing mineral veins, so much more continuous than 

 those found in the more irregular fissures of the other system, (Introd. 

 II. S. p. 3.) The most general rule will probably be, whatever be the 

 form of the elevated mass, that the direction of a transverse fissure 

 approximates to that of the dip of the strata, (supposing the mass stratified) 

 the direction of a longitudinal one, consequently, approximating to that 

 of the strike of the stratified beds. It should be observed, however, 

 that the present form of the elevated mass may in some cases diiFer 



