Cosmography

Concerning the Latitude of the Earth, or of Places.

Chapter VIII.

The latitude of a region or habitation is a segment of the same meridian, defined by the vertex, or pole of the horizon, and the circle of the equator; and it is always equal to the altitude or elevation of the pole above the horizon: yet they differ from one another in a certain respect. For the elevation or altitude of the pole is the arc of the meridian intercepted between the pole of the world and the horizon. But the latitude of a place is the arc of the meridian contained between the zenith of the heads and the circle of the equator. Now these two portions of the meridian (as the author of the Sphere demonstrates) are equal. Therefore, the number of the latitude of the earth, as well northern as southern, is written on the solid and the plane by tens (as is the custom); and similarly for longitude.

A woodcut diagram of a terrestrial or celestial sphere showing a grid of parallels. The diagram is labeled with cardinal directions: ORIENS (East) on the left, OCCIDENS (West) on the right, MERIDIES (South) at the top, and SEPTENTRIO (North) at the bottom. The outer ring is graduated with degrees from 10 to 90. The text "PARALLELI" is written vertically across the horizontal lines. The right side of the circular frame contains the text "LATITUDO MERIDI" and "LATITUDO SEPTEN". Decorative figures of wind-blowers or putti are positioned at the corners outside the circle.

Furthermore, lest anything be lacking to our calculation, we have deliberately appended this instrument, in which we have decided to show the equality of the latitude of any town and the elevation of the pole. You have here, therefore, most pleasant Reader, a movable horizon, which you may either depress or elevate from the North side, according to the number of degrees of the elevation of the pole, for a certain: