Thus far the route had lain over the beaten track between the continent and the Canaries, along the coast of Africa. As they now launched into the open sea, and as the Peak of Teneriffe sank under the horizon behind them, the heart of Columbus beat high with joy, while the courage of his officers and men died away within them. The Admiral kept two logs, one for himself and one for the crew, the latter scoring a distance less than that which they had really made, and thus keeping them in ignorance of their actual distance from home. His course was to the southwest. The sky, the stars, the horizon, the water, changed visibly as they advanced. Familiar constellations disappeared, others took their place. On the 13th of September, Columbus observed a strange and fearful phenomenon. The needle, which till then had been infallible, swerved from the Polar star, and tremblingly diverged to the northwest. The next day, this variation was still more marked. Columbus took every precaution to conceal a discovery so discouraging from the fleet, and one which alarmed even him. The water now became more limpid, the climate more bland, and the sky more transparent. There was a delicate haze in the air, and a fragrance peculiar to the sea in the fresh breeze. Aquatic plants, apparently newly detached from the rocks or the bed of the ocean, floated upon the waves. For the first time in the history of the world, the tranquil beauties and the solemn splendors of the tropical Atlantic were passing before the gaze of human beings. According to the journal of Columbus, "nothing was wanting in the scene except the song of the nightingale to remind him of Andalusia in April."