How much higher, could be determined by the angle formed by a stick pointing to the pole-star, in relation to one held horizontally.

If, instead of two sticks, we cut out a piece of metal or wood to fill up the enclosed angle, we get the earliest form of the sun-dial, known as the _gnomon_, and according to the shape of the gnomon the latitude of a place is determined.

Accordingly, it is not surprising to find that the invention of the gnomon is also attributed to Anaximander, for without some such instrument it would have been impossible for him to have made any map worthy of the name.

But it is probable that Anaximander did not so much invent as introduce the gnomon, and, indeed, Herodotus, expressly states that this instrument was derived from the Babylonians, who were the earliest astronomers, so far as we know.

A curious point confirms this, for the measurement of angles is by degrees, and degrees are divided into sixty seconds, just as minutes are.