Dick was greatly astonished when papa came on deck with the sextant in his hand, and "shot" the sun, as it is called; that is to say, he ascertained our exact latitude by observing through the instrument the height of the sun at noon.  Placing it to his eye, he watched it until it ceased to rise, the indicator showing the number of degrees it was above the horizon.  The _Nautical Almanack_ gives the height it would be at noon on that day along every parallel so that a few figures enabled him to ascertain how far north we had sailed.  The way to find the longitude, he explained to us, was by means of the chronometer.  An observation is then taken of the sun, moon, or a star, which would appear at a certain height above the horizon at that particular hour.