The hour lines of the sun dial do not quite show what we now mean by hours. Instead the hour lines divide the time between sun rise and sun set into 12 equal parts. This means that one "hour" during summer is longer than one "hour" during winter.
More about Solarium Augusti on wikipedia.
Below is a second variant of the applet. In this case where the shadow would fall right now is shown instead.
These applets were originally made (java code by Joakim Linde and graphics by Susanne Fagerlund) for the web site Tidsdokumentet (the time document), but since that site has not been online for quite some time the applets can go online again here.
