W.A Sheaffer pen

Hello all,

I came into possession this W.A. Sheaffer pen. To me, it seems to be in good condition and be able to write, however I have no idea how to add ink, or what to even search for to find information.

On the side of this pen is imprinted:

'W.A. Sheaffer Pen Co
Pat Aug 25 05 Fort Madison IA, USA
Dec 10 12- Jan 27- Oct 20-Nov 24 14

Does anyone have any idea where to start, or have any information about this pen type that could help me?

Thank you!