He replied;—"While we have had no land marks we have the heavenly bodies to guide us in the same way as your ships used to be steered by the observations of the sun's position at mid-day, and the stars by night. Besides this we have a very beautiful apparatus that was indeed foreshadowed in your day by the gyroscopic compass. This apparatus consists of a geographical globe, that after the principle of a gyroscope is set in motion, and is so arranged that it keeps in motion at a uniform speed for three months; this globe is provided with a pointer that points to a position on its surface corresponding to the position that the vessel is in, in relation to the earth, so that at all times we can tell within a mile or two the exact position in which we are. The steersman has simply to look at his globe, and by working handles, one controlling the earth's attraction, and the other two controlling the action of the lines of force see that his pointer is following the course laid down on the globe before him.
