In the Philosophical Transactions for 1858, I have given an account of the Joints of the Old Red Sandstone of the co. Waterford, and demonstrated in it the existence of the following Systems of Joints (page 348):—
First Conjugate System
. A . . 81 observations . . 7° 46' N. of E. (Mag.) . . 32° 26' N. of E. (True.) C . . 49 observations . . 6° 57' W. of N. (Mag.) . . 31° 37' W. of N. (True.)
Second Conjugate System
. A' . . 135 observations . . 33° 31' N. of E. (Mag.) . . 58° 11' N. of E. (True.) C' . . 47 observations . . 35° 23' W. Of N. (Mag.) . . 60° 3' W. of N. (True.)
Third Conjugate System
. A" . . 14 observations . . 30° 30'S. of E. (Mag.) . . 5° 50' S. of E. (True.) C" . . 12 observations . . 29° 10' E. of N. (Mag.) . . 4° 30' E. of N.(True.)
Fourth Conjugate System
. A'" . . 1 observations . . 10° 0' S. of E. (Mag.) C'" . . 6 observations . . 9° 30' E. of N. (Mag.) Since the publication of the foregoing account, I have found the system (A, C) in Donegal, Mourne, Cornwall and elsewhere, and have reason to believe it to be the most important of all the joint-systems of Waterford. I shall therefore call it the Primary System of Conjugate Joints, and the systems (A', C') and (A", C") I shall call correlated Secondary Systems of Conjugate Joints, as I believe that they can be shown to be simple mechanical consequences of the Primary System (A, C).
Fission product plateout and liftoff in the MHTGR primary system: A review