"I can do Plane, Traverse, Middle-Latitude, and Mercator's Sailing," I answered.  "I can also do a Day's Work; I can use my quadrant with accuracy; can find the Latitude by a meridian altitude of the sun, moon, or a star; can find the error and rate of the chronometer, and also the longitude by it; can determine the variation of the compass; can find the longitude by a `lunar'; can do the Pole Star problem; and--well, I think that is about all, sir, thus far."