Most commonly known as the Stirn Vest Pocket Camera, it can occasionally appear as Gray’s Vest Camera or under other names.

Describing it as “a rigid, disc-like camera, to be worn in conjunction with a specially-constructed false vest,” A Century of Cameras (by PHSNE member Eaton S. Lothrop, Jr., Morgan & Morgan, 1973) offers this history:

It was invented by Robert D. Gray of New York, patented in 1886, and manufactured by Western Electric Co. of New York. It produced “6 exposures, 1 5/8 in. diameter, on a 5 1/2 in. diameter dry plate.” The fake half-vest (front only) was short-lived. The shutter release and knob “protruded through an opening in the upper front section of the vest,” with the knob resembling a button.

By May of 1886, the camera could be worn under a regular vest. The camera was thinner, and more of it was easily concealed. The original octagonal plate had morphed into a circular shape. Months later, manufacturing rights were purchased by C. P. Stirn (of Stirn & Lyons in NYC).

Improvements were made, a German patent obtained, and production of the Stirn Vest Pocket Camera began. As a result of the changes made by Stirn, “the back was hinged at the bottom and had a knob at the top for fastening it shut. From this point on the camera was called ‘C.P. Stirn’s Patent Concealed Vest Camera,’” Stirn vest cameras were produced through 1892.

“The round brass body with the exposure dial (with or without clock hand) and the funnel type lens barrel gave it a unique appearance. Two main types were made, one for making four 6cm wide round exposures on a round film plate with a diameter of 17cm, the other with smaller lens funnel, for making six 4cm wide round exposures on a round plate with a diameter of 14cm.

This camera type fits not only in a vest pocket, it can be hidden in it so that the narrow lens opening looks through the vest pocket’s buttonhole. Thus the camera got its popular type name ‘buttonhole camera’, but also a detective camera, spy camera, and last not least, vest pocket camera.” (https://camerapedia.fandom.com/wiki/Stirn_Concealed_Vest_Camera ).