John Frederick Mascher was a German born clock and watchmaker in Philadelphia. He patented his stereoscopic viewing case on 8 March 1853 and it was the first American patent for a stereoscope. Stereo images were very popular from 1851 but viewing a stereo daguerreotype was challenging because of reflections. Viewing cases were introduced in Europe and the United States to create a good viewing experience.
Mascher aimed with his viewing case at the mass market and it was available in a variety of sizes and styles. He held a near-monopoly on the manufacturing of the cases and he sold tens of thousands in a brief period, as daguerreotypes disappeared in the early 1860s with the introduction of the wet collodion process. From that moment, the cases were made suitable for ambrotypes and tintypes, which were based on the collodion process.
Mascher's viewing case is a foldable viewer made of wood and covered by leather. The viewer consists of a plate on which the lens panel and the holder with the daguerreotype are placed. Both can't be locked, so viewing the image is a bit cumbersome. It's best to place the daguerreotype in your palm and hold the lens panel between your thumb and forefinger.
The daguerreotype is covered by a copper passepartout and a glass plate protects the passepartout and the image. The image is a quarter plate daguerreotype (8,1 x 10,8cm), made by an unknown photographer. The image is of good quality and offers an attractive stereo depth effect.
- Stereoscopes: the first one hundred years, Paul Wing, 1996