You need water while in use and the ability to empty the water immediately and let the stone dry thoroughly, when not in use. It appears in your photograph, that there is a M/F vertically slotted 'gate,' for just that purpose, to the right of the stone.
I used one, like yours, only larger with a foot pedal. while working on a farm, as a kid, back in 1960. Technology just simply hadn't replaced it yet and there are undoubtedly, today, places on this planet in which this tool/device would represent, for them, a 'state of the science.'
Nice find by-the-way. Should clean-up very nicely.