Try changing the latitude in the applet to the right and see how the hour marks change. There are several ways to overcome these problems. The hour marks can then be drawn by trigonometric calculations, correcting for the sundial's latitude. Another solution is an equatorial sundial, where the base plate is titled at an angle equal to the latitude, and the style is perpendicular to the base, which will align it with the earth's axis. Oh, yes, there's one more problem.
Sundials only measure local solar time.
If a friend had a sundial 5 degrees longitude to the west of your sundial, his sundial would read a different time than yours. This difference is only affected by longitude, not latitude. To standardize things, the earth was divided into 24 time zones in the 1840's, each to be one hour different from the next. The Egyptians worshipped the god Horus , son of Osiris and Isis, as the god of dawn. The tilt of the earth's axis is the reason for our seasons.