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XI. On the Joint-Systems of Ireland and Cornwall , and their Mechanical Origin. 
By the Rev. Samuel Haughton, M.D., Fellow of Trinity College , Dublin. 
Eeceived February 8, — Eead February 25, 1864. 
Contents. 
Introduction. 
Part I. On the Joint-Systems of the co. Donegal. 
Part II. On the Joint-Systems of the Mourne and Newry Mountains. 
Part III. On the Joint-Systems of Cornwall. 
Part IY. On the Joint-Systems of the co. Fermanagh. 
Part Y. General Conclusions from the foregoing Observations. 
Part VI. Mechanical Theory of Eock Joints, and its comparison with the conclusions drawn in Part Y. from 
observation. 
INTEODU CTION. 
In the Philosophical Transactions for 1858, I have given an account of the Joints of the 
Old Eed Sandstone of the co. Waterford, and demonstrated in it the existence of the 
following Systems of Joints (page 848) : — 
A . . 81 observations . 
C . . 49 
A' . .135 observations . 
a . . 47 
A" . . 14 observations . 
C" . . 12 
A'" . . 1 observation . 
C'" . . 6 observations . 
First Conjugate System. 
7° 46' N. of E. (Mag.) 
6° 57' W. of N. „ 
Second Conjugate System. 
38° 31' N. of E. (Mag.) 
35° 23' W. of N. „ 
Third Conjugate System. 
30° 30' S. of E. (Mag.) 
29° 10' E. of N. „ 
Fourth Conjugate System. 
10° 0' S. of E. (Mag.) 
9° 30' E. of N. „ 
32° 26' N. of E. (True.) 
31° 37' W. of N. „ 
58° 11' N. of E. (True.) 
60° 3' W. of N. „ 
5° 50' S. of E. (True.) 
4° 30' E. of N. „ 
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 
3 g 2 
s 
