Page:First Voyage Round the World.djvu/251

 "The true meridian may also be ascertained, or rather the equinoctial line, which cuts the meridian at right angles, by observing the points where the sun rises and sets, and by observing how much they are distant from the equinoctial either to the north or to the south. For this purpose an astrolabe is formed with the globe; that is, a circle is made representing the earth's circumference, divided into 360 deg. At sunrise fix two pins in the circumference, in such a manner that a line drawn from one to the other should pass through the centre, and place the pins so that both should be in a line opposite the sun's center. Place two other pins in the same way in the circumference when the sun sets. You will thus see how much the sun declines from the equinoctial line, either to the north or to the south. And as many degrees as the pins are distant from the equinoctial, so many degrees the the sun's declination. Having found the sun's rising and setting, you will also find the medium distance; that is, the meridian line, and afterwards you will see how much the compass or magnetic needle north-easts or north-wests. You will infer from this how far you are from the Fortunate islands; that is, from Tenerife towards the east or the west. This method has been tried by experience.