And, as a geodesist, it would be remiss of me not to point out that the
heliograph was preceded by the heliotrope, a device to make survey stations
more visible from long distances, invented by the father of modern geodesy,
Carl Friedrich Gauss, in the early 1800s.
-- Richard Langley
Professor of Geodesy and Precision Navigation
On Wed, 23 Jun 1999, Peter Mayer wrote:
>Fernando Cabral wrote:
>
>>As far as I know, what you call "heliograph" we just call
>>"mirror". Nevertheless, there can be other names and usages
>>if you check with the different armed forces and other people
>>with survival training.
>>
>>As to me, the only name I know is really "mirror", even for
>>those especially-made mirrors with a small hole in the centre
>>(to be used to collimate the light ray).
>>
>>Again, since you can clearly use such a device to send
>>Morse code you can say you "write" with the sunlight,
>>than calling it "heliograph" should not be unacceptable.
>
> I'm attaching a tiny JPEG illustration, taken from an ancient
>dictionary, which accompanies the definition of 'heliograph'. The
>instrument definitely has a mirror! But as you'll see, it also incorporates
>a telegraph key and a sighting vane. My recollection is that they were
>used by military forces in the 19th century in places like India. (I have
>a half-baked recollection that Kipling refers to one in a poem...?Is that a
>source?!)
>
> cheers,
>
> Peter
>
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Richard B. Langley E-mail: [EMAIL PROTECTED]
Geodetic Research Laboratory Web: http://www.unb.ca/GGE/
Dept. of Geodesy and Geomatics Engineering Phone: +1 506 453-5142
University of New Brunswick Fax: +1 506 453-4943
Fredericton, N.B., Canada E3B 5A3
Fredericton? Where's that? See: http://www.city.fredericton.nb.ca/
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