19.182 dry and wet photography

               Humanist Discussion Group, Vol. 19, No. 182.
       Centre for Computing in the Humanities, King's College London
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   [1] From: Elisabeth Long <elong_at_uchicago.edu> (43)
         Subject: Re: 19.173 "dry photography"?

   [2] From: Willard McCarty <willard.mccarty_at_kcl.ac.uk> (24)
         Subject: wet photography used as computer storage

--[1]------------------------------------------------------------------
         Date: Fri, 29 Jul 2005 06:47:47 +0100
         From: Elisabeth Long <elong_at_uchicago.edu>
         Subject: Re: 19.173 "dry photography"?

Dry photography, like the memex machine, was more an imagined technology
than an actual existing process, though Bush does cite a couple of existing
technologies that were close to what he had in mind. The problem Vannevar
Bush was struggling with was that his imagined memex machine needed to copy
books and notes and instantly store the resulting images, but all
photography at the time required some sort of wet processing in order to
develop the final image and so was not practical as a technical solution for
the memex. For anyone unfamiliar with 'As We May Think', it is commonly
cited as the conceptual origin of hypertext and provides amazingly prescient
descriptions of modern-day computing coupled with quaint ideas of how this
might technically be brought about. The article is available in the archive
of The Atlantic where it was first published in 1945:
http://www.theatlantic.com/doc/194507/bush

The first technology Bush cites in this regard is 'dry plate photography'
which is not quite the same as dry photography. Originally, photographic
plates needed to be exposed while the chemical coating was still wet which
severely limited the portability of the camera. The invention of dry plate
photography in which the wet part of the process occurred *after* the plate
was exposed was a significant technological advance, but was still not
sufficient for Bush's needs. He nevertheless cites this as indicative of
the possibility that true dry photography may be the next technological
advancement.

The second technology that Bush cites is facsimile transmission which,
amazingly enough, existed in 1945. The process was fundamentally an analog
process, though the image was transmitted line by line in a manner similar
to how a scanner works today. Besides the poor quality of the image, the
other problem with this technology for Bush's purposes was that it produced
a paper end product, whereas he wanted the resulting copy to be on microfilm
(in order to compactly store the vast quantities of data that he imagined
the memex would hold).

The Polaroid camera, which was introduced three years after Bush wrote his
article, did provide the instant development that Bush wanted, though it was
not actually a dry process until the introduction of the SX-70 in 1972.
Before that it consisted of a peel-apart wet process. At any rate, it would
still have fallen short in that it didn't produce microfilm.

Xerography was also in the works at the time that Bush was writing (it was
publicly described in concept by 1948 though not brought to market until the
1960s). The etymology of the word, according to the OED is [f. XERO- +
-GRAPHY, after photography.] ('xero' meaning dry, fyi) and so comes quite
close to the literal meaning of what Bush was calling for (though again it
problematically produced paper copies instead of film).

Digital scanners/cameras are, of course, the true realization of Bush's
dream - they capture faithfully, store instantly and in a format that allows
reams of data be held within a small space. And they don't use any water!

--[2]------------------------------------------------------------------
         Date: Fri, 29 Jul 2005 07:12:14 +0100
         From: Willard McCarty <willard.mccarty_at_kcl.ac.uk>
         Subject: wet photography used as computer storage

The ongoing discussion of "dry photography" stirred my memory of a
wet-photographic device used as a mass-storage medium for computing
in the 1960s. This was the IBM Photostore device (IBM 1360),
installed and operational for a time at the Lawrence Radiation
Laboratory in Berkeley, California. At the time, as a young student
in physics at Berkeley, I worked at the Lab in the computing centre
and saw its installation and operation. We called it "chip store"
because its recording medium comprised small pieces of film
("chips"), about 3-4 inches by 1 inch, stored 32 to a box. Chips were
written by an electron beam, then developed in a chemical processor,
washed, dried, and put back in their box for reading when the data on
them was needed. All operations were performed robotically. The
device was a marvel of the time. A detailed technical description may
be found
at
http://mail2.computerhistory.org/pipermail/inforoots/2004-February/000611.html
and some photographs at
http://www.computerhistory.org/VirtualVisibleStorage/artifact_main.php?tax_id=02.07.01.00.

Yours,
WM

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Received on Fri Jul 29 2005 - 02:29:50 EDT