Pneumatic Telescope Commutator of 1889
By Robbie Rhodes
I enjoyed the concise history of programmed machines provided by Fritz Gellerman (digest 960225). Here is another unique machine, described in the book "Stars and Telescopes" by David P. Todd; Boston: Little, Brown & Co., 1899, p. 360.
"An arrangement of multiple cameras for observation of solar eclipses was first worked out by the writer for the total eclipse of 22 December, 1889, at Cape Ledo in West Africa. In all, 23 instru- ments, chiefly photographic, were attached to a massive polar axis, and pointed parallel to each other, following accurately on the eclipsed Sun.
"The engraving opposite illustrates many of them; also in the foreground are the pneumatic contrivances by which exposing shutters, plate-holders, and all other moving devices for eclipse observation were operated automatically.
"The control was effected by a perforated strip of paper, similar to the music sheets now commonly used in automatic organs. Each perforation in the eclipse sheet represented, not a musical note, but a mechanical movement of some particular device.
" ... The set-up worked perfectly but, unfortunately, on the day of the eclipse the Sun was totally obscured by clouds."
The engraving apparently was produced by a non-astronomer: although the rendering of the player pump-organ seems accurate (the artist probably visited a local organ store), the astronomical devices seem contrived, and the paper-roll "eclipse sheet" looks like it was the target of a shotgun blast! The caption says: "The Pneumatic Commutator and Photographic Battery of Eclipse Instruments (Todd)"
-- Robbie Rhodes
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(Message sent Wed 28 Feb 1996, 03:49:23 GMT, from time zone GMT-0800.) |
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