That looks like the radius grinding attachment for the Cincinnati #2 tool and cutter grinder, with an incomplete work head mounted on it. Here's a scan from page 73 of Cincinnati publication M-737-9 (from sometime after July 1949 when M-737-7 was published).
Added in edit: This is a #2 radius grinding attachment, intended to put 0-1" radii on shell mills and face mills up to 12" diameter. (Manual says "the ingenious operator" can find ways to grind larger radii.) There is also a #1 radius grinding attachment intended for smaller ball nose milling cutters, which does not have the large "pivot well" which hangs off the back of the TC grinder table. Both the #1 and #2 radius grinding attachments work with the #2 tool and cutter grinder, or any similar machine such as a KO Lee, or indeed Oliver.