Tides. Variation of the compass. Between Napakiang and the Sugar Loaf there is no place for ships to lie in safety; the bay immediately to the north was examined by Mr. Mayne, master of his Majesty's ship Alceste, when two shallow harbours were found. The flood runs to the northward and eastward, along shore, and the ebb in an opposite direction. The rise and fall is about nine feet perpendicular. High water at full and change IX. The variation of the compass, determined with great precision by the transit azimuth instrument, was 52′ westerly. The longitude of the Lyra's observatory at Napakiang by the mean of thirty-six lunar observations on both sides. of the moon, is 127° 37′ 28′′ east; by four chronometers, agreeing nearly, 127° 38' 30' east. The latitude is 26° 13′ 39′′ north. Mean by sextant 127. 34. 58 W. Mean 127. 35. 37 by circle. Mean longitude by 36 lunars 127. 37. 28 Longitude by chronometers 127. 38. 30 east of Greenwich. LATITUDE OF NAPAKIANG. By Meridian Altitudes of the Sun and Altitudes taken near Noon. 22d mean 2 A.M.&2 P.M. 26.13.24) 26.13.29} circle. Latitude by mean of 3 meridian altitudes 26°. 13′. 39" sextant and circle. mean of 5 altitudes near noon 26 13. 50 sextant. 26. 13. 28 circle. 26. 13. 39 north. VARIATION OF THE COMPASS AT NAPAKIANG. The declination of the magnetic meridian was ascertained with considerable precision by means of the transit azimuth instrument: the needle seldom showed the same variation, as it oscillated about ten minutes, but the mean position of the magnetic meridian was 52' 10" west of the true. A coral reef was selected for the place of these observations, in order to avoid the attraction arising from buildings, or from inequalities in the ground. Variation observed on board by Walker's Azimuth Compass. 29th Sept. 1816, P. M. ship's head W. by S. variation by 0°. 51′. 30" west. 0 53 . 30 1. 17. 30 1st azimuth 2nd 3rd Amplitude 1st azimuth 1. 15.00 55. 30 34 0.37 .00 0 48.00 0.52. 39 west. TABLE OF OBSERVATIONS MADE WITH DR. WOLLASTON'S DIP SECTOR: WITH AN ENGRAVING, AND A DESCRIPTION OF THE INSTRUMENT, AND DIRECTIONS FOR ITS USE. |