ANAGLY PHS 171Unfortunately, at the time this is written the Vectograph chem-
icals are not available, but it is to be hoped that they will again
be offered in the near future. If for any reason that is not done, we
hope the formulae will be made public. This process is far too
valuable to be lost to the stereo world, We have been informed by
Mr. Joseph Mahler, the originator of the process that some de-
cided improvements have been made in the process, and that these
will make 16mm motion picture film production wholly practical.
It will also have added possibilities for the makers of trans-
parencies.
Anuglyphic Spacing.-In printing the anaglyph it must be re-
membered that this is a true print, held in the hand. We are
fully aware of that fact, and the eyes naturally converge upon the
physical sheet which bears the image. For this reason it is usually
advisable to print the anaglyph so that objects in the plane of
primary interest shall be registered as nearly as parallax will per-
mit, leaving greater differences to be exhibited by images of less
important objects.
See Chapter 14 for general discussion of polarized light in
stereoscopy, and additional material about the Vectograph.
Integrated AnagZyphs.-A third type of stereogram which prop-
erly falls into the anaglyphic classification is one in which the
two images are divided into narrow vertical strips in which right
and left elements alternate. These stereograms are made to be
viewed without any filters, viewers or other accessories.
Such stereograms have been made in several types. The original
consists of alternate strips set behind a grid of alternating opaque
and transparent bars. In theory the right eye sees past a bar
obliquely to perceive a “right” element, while the left sees past
the bar from the other side to see a “left” element.
In the resulting stereogram, a certain degree of stereo relief is
apparent when the eyes are within a certain restricted area. Mov-
ing the head to one side or the other introduces either neutral re-
lief or definite pseudoscopy.
To overcome inherent defects, the black bar grid was replaced
by lenticular elements so the alternating ray paths could be pro-
duced without wasting half the brilliance upon opaque bars and
to remove the unsightly grid.
The lenticular film considerably improved the unsightly