Unusual Sundial.

Came across this unusual object in Sidney Sussex College garden, Cambridge. It looks like a type of sundial and has faded markings around the centre circle. On each side of the plinth are barely readable words. It seems it is dedicated to Huw ? Arnold. Reader, Thinker, Listener. It also says the following :- No one can guarantee success, you only can deserve it. To have enjoyed the sun is reward enough. I liked these words. Everything else including the date had worn away.