Walter O'Reilly's patent number 18,823 of 26 July 1888 briefly described an instantaneous camera with ground glass screen where the plates are transferred to and from the darkslide by an opaque bag which is slipped over the carrier. The Demon was made in Birmingham by W. Philips and sold by the American Camera Company of London. It was remarkably successful with advertising claiming an average sale of 2000 per week and 100,000 sold in twelve months.

Two versions of the camera were made. The original model, later designated the number 1, was produced in a 2¼ inch square plate size and the number 2 for 3¾ inch square negatives and an achromatic doublet lens was announced in 1890.

The American Camera Company ceased trading in 1894.