Combination cameras were manufactured in Boston by the Blair Tourograph & Dry Plate Company from 1882 to 1894 and “are traditional field designs offered with a unique [patented] accessory plate-holder extension mounted at the rear” (https://www.collectorsweekly.com/stories/226546-blaircombination-camera-1882). In an 1882 pamphlet,

From time-to-time, PHSNE’s warehouse crew comes across an unusual camera as they sift through donations and prepare for auctions. One recent find was a Minolta Maxxum 7000, destined for Photographica 89, PHSNE’s one-day dealer show, sale, and auction for everything