P3D Re: Mister Expert

[roberts@xxxxxxxxxxxxxxxxx (John W Roberts)]

>Date: Mon, 4 Jan 1999 21:26:45 -0700
>From: "Michael" <blue_jay@xxxxxxxxxxx>
>Subject: P3D Re: Mister Expert

>>I would prefer to gently correct such errors, much as I prefer to gently
>>correct those who refer to Holmes stereoscopes as "stereopticons"...

>Ok, now I feel stupid.  Which is which?
>Michael (Bluejay) Henderson

To quote from "Webster's Encyclopedic Unabridged Dictionary of the
English Language", which I just happen to have handy:

stereoscope: "an optical instrument through which two pictures of the same
  object, taken from slightly different points of view, are viewed, one by
  each eye, producing the effect of a single picture of the object, with the
  appearance of depth or relief" [1830-40]

stereopticon: "a projector usually consisting of two complete lanterns
  arranged so that one picture appears to dissolve while the next is forming"
  [1860-65]

The origin of the confusion of the two terms is probably the similarity
of the names, the fact that they both have two optical paths, the record
that the two terms came into use within a few decades of one another,
and probably somebody not quite correctly recalling how things were in
"the good old days".

Note that the definition of "stereoscope" is very general - a slide viewer
might be regarded as a stereoscope, though that is not usually done. Further
specifying "Holmes stereoscope" narrows down the definition quite a bit
further, though I think there are also several versions of the Holmes
stereoscope. When people use the term "stereoscope", they are almost always
referring to the Holmes stereoscope.

Some people have suggested that the word "stereopticon" be redefined to
refer to the Holmes stereoscope, but I would consider this to be inadvisable,
since the functions of the two devices are so different, and since there
are still quite a few stereopticons (the old projectors with the dissolve
function) in existence.

John R


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