Page:Great Neapolitan Earthquake of 1857 Vol 2.djvu/61

30 observation, though not trustworthy, merely because the great change of declination given by it, occurs near the same region where in passing southward, I had found the local action of the ferruginous rocks so great, and as an indication to some future traveller, of the desirableness of ascertaining afresh, the declination upon these iron shot rocks.

The point of observation was at north lat. 40° 13', E. long. 15° 23', at 3h 16', Greenwich time, by chronometer (19th February, 1858), sun bore 76° 3' W. of N.

Hour angle Sun's azimuth Sun's bearing by compass    Western declination

= 61° 44' 12"·45 = 62° 34' . . . . W. = 76° 30' . . . . W. of N. 138° 37' 180°  41° 23' W.

13° to 15° W. being the usual declination everywhere else hereabouts. Although I cannot rely upon the observation itself, made through a thick haze, it yet derives I find, a strong confirmation as to its truth, from the only possible observation of a terrestrial azimuth. The town of Buonabitacola was the only one visible, and it bore from this spot, by compass, 84° 30' W. of north. Referring to its bearing from the true meridian, by Zannoni's map, I find it = 136° W. of N.

and 136° 0'

84° 30'

41° 30' difference = declination.