Solar Eclipse Telescope Controlled
by Music Roll
by Robbie Rhodes (990812 MMDigest)
Over 100 years ago a punched paper "music roll" was used to control
a complex telescope built to photograph a total eclipse of the sun.
It is described on page 360 in the book, "Stars and Telescopes", by David
P. Todd, published in 1899 by Little, Brown & Co., Boston.
| An arrangement of multiple cameras
for observation of total solar eclipses was first worked out by the writer
in 1889, for the eclipse of the 22d December in West Africa.
In all, 23 instruments, 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 sleets 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 obscured by clouds.
The caption says: The Pneumatic Commutator and Photographic Battery
of Eclipse Instruments (Todd) (As mounted at Cape Ledo, Africa, for the
total eclipse of December 1889)
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
High resolution image: solartelescope2.jpg
12 Aug 1999