John F Mascher (? - 1863) was an American watchmaker and inventor. Mascher lived in Philadelphia and was an elected member of the City Council.

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Mascher also experimented with daguerreotypes and stereoscopic daguerreotypes. When in the beginning of May 1852 the Scientific American reprinted a short notice on the invention of stereoscope from the London Mining Journal, Mascher responded with a letter that stated:

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"Messrs. Editors - Directly after seeing the extract from the "London Mining Journal" in No. 34 of the Scientific American, I succeeded in re-producing the solid daguerreotype. My stereoscope is 9 inches long, 6 high, and 5 deep; my daguerreotypes are half sizes, placed upright in each end of the box (stereoscope); I have two mirrors, diverging at an angle of sixty degrees from the centre of the front of the box; there are two sight holes, two inches apart, in the middle of the front of the box; the light is admitted from the back. The instrument produces the most astonishing effect; it brings out the picture in bold relief, just as if the subject were standing before you in reality. It requires to be sen to be fully appreciated.

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I have made a decided improvement on the above instrument: I take two pictures on one plate, two and a quarter inches apart; or, what is still better, on two plates joined together afterwards. I always place my two cameras at an angle of thirty degrees, in taking the pictures, keeping the eye of the subject directed in a line drawn directly between the two cameras, thereby producing what we might call a right and a left pictures.

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When I wish to produce the solid pictures, I simiply look at the so arranged plate, through a common opera-glass, having the concave glasses taken out and convex ones put in their place, although the latter are not absolutely necessary...

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I expect that our leading daguerreotypists have taken the matter in hand, and I expect to see them produce beautiful pictures which will rapidly take the place of the old kind."

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Based on these early experiments in 1853 Mascher patented a special device that allowed to combine the lenses of a stereoscope and a daguerreotype case containing two portraits taken at different angles. This device was extremely popular during the 1850s, especially in America. Below is a newspaper report from the National Fair in Washington D. C. on the exhibit of Mascher:

 

"In no part of the building is te crowd more dense than where Mr. Mascher exhibits his stereoscopic daguerreotype cases. By looking through the lenses in these cases, one sees the otherwise ordinary daguerreotypes, raised out from the background, as though breathing before him.

 

Indeed, so great is the illusion produced, that a lady on looking through the lenses at the picture of a lady holding music notes in her hand, gazed so intently that the gentleman accompanying her, wished to know what rivetted her attention so. "Hush!" said shi, half reproachingly, "She was just going to sing."

 

These cases are not larger than the ordinary daguerreotype case, and there is but a trifling difference in the cost."

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In 1855 J. F. Mascher also invented a stereoscopic "medallion". These were also exhibited at the national fair. The same newspaper noted:

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"What draws the attention of the ladies most, is the collection of stereoscopic medallions which Mr. Mascher has on exhibition, for which he obtained a patent on the 16th of january last. Some of these medallions (of gold) are note quite as large as ordiary sized watches, yet containing pictures as large as the quarter sized case.

 

Ladies may by this invention have the counterpart of the object of their affection constantly by their side, though the orginal may sometimes be truant."

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