O'Eeilt.y — On Jointing in Rocks about Dublin, 8fc. 137 



No. of Magnetic LOCALITY OF OCCURRENCE. OBSERVATIONS. 



Jointing. Bearing. 



428 25° 30' W. Giant's HiU, Rush. Coast. — 



479 22° 30' W. ClonsiUa Bridge. — 



543 25° 30' W. Eathgar Quarry. — 



Number of Directions observed, 7. 



171° 30' ^ 7 = 24° 30' W. mean value. True bearing, 46° 10' "W. 



258 



8° 30' 



W. 



Sandyford. — 



259 



10° 30' 



vv. 



,, — 



270 



9° 



w. 



Malahide Station Quarry. — 



291 



8° 



w. 



,, ,, ,, — 



304 



6° 



w. 



Malahide Coast. — 



367 



7° 30' 



w. 



,, ,, — 



459 



8° 30' 



w. 



Lough Shinney Coast. — 



460 



6° 30' 



w. 



;; ,, ,, 



481 



7° 30' 



w. 



Dodder River (Milltown). — 

 Number of Directions observed, 9. 





72 



'^9 = 



= 8° W. mean value. True bearing, 29° 20' W. 



457 14° 30' W. Skerries Coast. — 



353 12° W. Malahide Coast. — 



373 14° 30' W. „ „ — 



Number of Directions observed, 3. 



41° ^ 3 = 13° 39' W. mean value. True bearing, 34° 59' W. 



340 19° W. Malahide Shore. — 



482 16° 30' W. ClonsiUa Bridge. — 



391 20° W. Donabate Coast. — 



Number of Directions observed, 3. 



55° 50' ^ 3 = 18° 30' W. mean value. True bearing, 39° 50' W. 



332 3° 30' W. Malahide Coast. — 



351 



3° 30' 



W. 





352 



1° 



w. 





360 



4° 



w. 





369 



3° 



w. 





416 



4° 30' 



w. 



Donabate Coast. 



494 



4° 30' 



w. 



Gollarstown Bridge 



520 



2° 30' 



w. 



Lucan. 



Number of Directions observed, 8. 

 26° 30' ^ 8 = 3° 18' W. mean value. True bearing, 24° 38' W. 



Summarizing these results, comparing them with those obtained 

 in 1880, and taking the mean directions for the two series of observa- 

 tions, the annexed Table is obtained, relative to which the following 

 observations may be made : — 



