Patented Aug 18, 1891 and Nov. 10 1896, Edgar Manufacturing Co.  Slide action, the barrel turns to vary grind, spring loaded chimney to hold a chunk or block of chocolate. It was rubbed back and forth in the same manner as the "Edgar" nutmeg grater.

"Rare: except in ads, I've never seen one for sale." pg. 10, Franklin, Linda Campbell 300 Years of Kitchen Collectibles. Florence, Al:  Books Americana, 1991.

Tin and cast iron, overall length 8-3/4", height 5-1/2" to top of ring, chocolate holder is 2-7/8" x 2" x 1-7/8".