O'Reilly — On the Occurrence of Serpentine at Bray Head. 511 
may point out that, while the direction as stated by the Survey Memoir 
is roughly given as JN'.E./S.W., the true bearing is IST. 61° E., while 
that of the fault by which it is dislocated is JS". 57° E. (dip S. 70°) 
where determined, that is on the railway side ; the difference being 
only 4°, it is probable that both directions are the same. The interest 
of exact measurements in this case is, that taking both directions at 
the value IN". 61° E,, we have very correctly the line of the southern 
coast of Ireland, as also that of the faults shown as existing in the 
Kilkenny coal-field, both of which I brought before the Academy in 
the Paper written to prove the importance of coast-line directions on 
the physical and geological structure of a country. The inspection of 
the map of Ireland shows that this direction manifests itself in a series 
of faults and lines of structure extending between the south coast and 
a line parallel to it passing through the mouth of the Shannon. 
