Navigation, I may be permitted to repeat, is the mathematical science of finding ships’ positions at sea and of laying down courses to be followed. For the designation of positions latitude and longitude are used, latitude being measured north and south from the equator to the north and south poles, the equator being zero degrees of latitude, the poles being ninety degrees north and ninety degrees south latitude. Longitude is measured from zero degrees to 180 degrees east and west from the meridian running from the North Pole to the South through Greenwich, England, 180 degrees east longitude marking the same meridian as 180 degrees west longitude. For instance, Three Kings Island, the tiny island which is the northernmost land of the New Zealand group, is located as follows: Latitude 34° South; Longitude 172° East. This means that this island is 34 degrees south of the equator and 172 degrees east of the meridian of Greenwich. Actually navigation is a problem in spherical trigonometry and astronomy, depending principally, nowadays, upon an instrument called a sextant, which is used to measure the altitude above the horizon of a celestial body (sun, moon, or stars), and upon a very accurate timepiece, called a chronometer, which shows the time of a given meridian—generally the meridian of Greenwich, England. In practice, however, it is necessary to know no mathematics other than arithmetic, for the formulas have been simplified and handbooks have been compiled which eliminate any necessity for the practical navigator to delve into the intricacies of spherical trigonometry, a subject that would frighten most sea captains more than all the other perils of the deep. There is another but less accurate method, called “dead reckoning,” which is used in connection with the more accurate science, and is used by itself when clouds obscure the sky or fogs hide the horizon. When land is in sight both these methods largely or entirely give way to “piloting,” which makes possible the accurate finding of a ship’s position by reference to known objects ashore. I shall not attempt to explain all the intricacies of navigation, for even a simplified complete explanation would in itself become a small book. There are many books on navigation. Nathaniel Bowditch’s exhaustive treatises have been revised many times and the whole compilation is kept up to date so that, while Bowditch himself died in 1838, the book bearing his name, and still referred to almost universally as “Bowditch,” is accepted as a peerless authority. But it is a huge tome, and other practical books, such as “Elements of Navigation,” by W. J. Henderson, are available for the person who wishes to profit by a simpler, if less exhaustive, explanation. To these two books, and to a dozen others, I refer the interested reader anxious to learn what, after all, is beyond the range of this outline.