I own many silver holloware pieces, but I have never seen anything like this!
Yes, that's such an interesting piece! When the knob was turned, those niches would open to reveal condiment bottles. I love that it's called a "magic" dinner caster, the word magic makes it seem so special!
What is this?
That is a magic caster! One is the object itself, and the other is a patent model that was submitted to the US Government by the manufacturer, R. Gleason & Sons, for a patent. This would be placed on a dinner table and when the knob at the top was rotated, it would spin and reveal condiment bottles in those little openings!
Why is the magic dinner caster made of silver plate?
Silver plate was an innovation in the late 18th century. It allowed for objects that looked like they were pure silver, which was very expensive, but could be purchased by middle class people. Because of this, affordable silver plate objects became very popular.