The navigators could, however, manage this all very well, provided they could be sure of seeing the sun every day at proper times, particularly at noon. The sun passes through different portions of the sky every different day of the year, rising to a higher point at noon in the summer, and to a lower one in the winter. The place of the sun, too, in the sky, is different according as the observer is more to the northward or southward. For inasmuch as the sun, to the inhabitants of northern latitudes, always passes through the southern part of the sky, if one person stands at a place one hundred or five hundred miles to the southward of another, the sun will, of course, appear to be much higher over his head to the former than to the latter. The farther north, therefore, a ship is at sea, the lower in the sky, that is, the farther down toward the south, the sun will be at noon. Navigators, then, at sea, always go out upon the deck at noon, if the sun is out, with a very curious and complicated instrument, called a sextant, in their hands; and with this instrument they measure exactly the distance from the sun at noon down to the southern horizon. This is called making an observation. When the observation is made, the captain takes the number of degrees and minutes, and goes into his state room; and there, by the help of certain tables contained in books which he always keeps there for the purpose, he makes a calculation, and finds out the exact latitude of the ship; that is, where she is, in respect to north and south. There are other observations and calculations by which he determines the longitude; that is, where the ship is in respect to east and west. When both these are determined, he can find the precise place on the chart where the vessel is, and so--inasmuch as he had ascertained by the same means where she was the day before--he can easily calculate how far she has come during the twenty-four hours between one noon and another. These calculations are always made at noon, because that is the time for making the observations on the sun. It takes about an hour to make the calculations. The passengers on board the ship during this interval are generally full of interest and curiosity to know the result. They come out from their lunch at half past twelve, and then they wait the remaining half hour with great impatience. They are eager to know how far they have advanced on their voyage since noon of the day before. In order to let the passengers know the result, when it is determined, the captain puts up a written notice, thus:-- Latitude, 44 deg. 26'. Longitude, 16 deg. 31'. Distance, 270. The passengers, on seeing this notice, which is called a _bulletin_, know at once, from the first two items, whereabouts on the ocean they are; and from the last they learn that the distance which the ship has come since the day before is 270 miles.