206 THREE-DIMENSIONAL PHOTOGRAPHY
be printed in periodicals, the method has perhaps greater po-
tential commercial value than any other. But it has only the
slightest resemblance to that result which the stereographer knows
as stereoscopy.
The stereoscopic effect in the bar-screen is considerably less
realistic than it is in the Vectograph, for example. The Vecto-
graph presents an unmistakable, an unchanging, and normally
undistorted true stereoscopic image. The only objections are the
resemblance to a miniature model, the absence of orthostereo-
scopic dimensions, and the absence of visual isolation. For these
reasons not even the Vectograph can replace the conventional
stereogram and stereoscope among stereographers. When one sur-
rounds his eyes with the hood of the viewer, it is like opening
a door to distant places. There is almost a bodily transportation,
something which the hand-held free-vision image can never
imitate.
Still, the bar-screen is an ingenious method, and one follows
the history of the work by Ives, Lumiitre, Bessiitre, Draper and
Winneck with deep interest. The mere fact that for our specific
purposes the method is inferior is no reason why these men
should not receive our admiration and respect.
The original suggestion for the use of the grid came from
Berthier in 1896. Acting upon his suggestion, Ives in 1903 in-
vented the system, giving it practical design. This was greatly
improved by Estanave in 1906, and upon his improvements were
based the Autostereo plates of 1907. To overcome the necessity
for viewing the print from the one correct viewing angle, Lipp-
mann suggested the lenticular base in 1908, and proceeded to
make grid stereograms, using the lenticular grid.
Estanave elaborated the use of the bar screen and in igio
introduced the “magic picture” which by a slight side shift
changed its nature, but later he went back to stereoscopic effects
and greatly improved Lippmann’s lenticular process in 1925,
the same year in which Bessiitre made use of the same process.
Brewster in 1860 suggested that the parallax involved in images
made by different portions of a large lens was sufficient for stereo-
scopic effects. Lehmann in 1878 produced such effects, and in
1 goo Boisonas made some improvements upon the dimensions of
the apertures used. Thus the lens was waiting when the grid