About thirteen years ago, when officer of a vessel trading from London to Australia, and in the daily practice of verifying the error of the compass by azimuth's declination, the idea first occurred to me of projecting the sun's path on the plane of the horizon; and during the voyage I succeeded in solving the problem, and constructed a diagram which I used daily while at sea for several years, until I gave up long voyages, and had no further occasion to trouble about azimuths.