heliograph


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heliograph

(hē`lēəgrăf) [Gr.,=sun-writer], signaling device using flashes of sunlight. It has two mirrors that are used to reflect sunlight on a distant point and a shutter through which the sunlight passes so that messages may be transmitted in telegraphic code by means of long and short flashes. It was used in ancient times and as recently as the 19th cent. by the U.S. army in the SW United States and by the British army in India.

Heliograph

 

(1) In meteorology, an instrument for automatically registering the duration of sunshine, that is, the time when the sun is above the horizon and not covered by clouds. There are many types of heliographs. The most widespread in the USSR is the Campbell-Stokes heliograph, in which a stationary sphere serves as a lens that gathers the rays of the sun onto a cardboard strip marked off by hour lines. The strip is burned through by the sun’s rays if irradiation exceeds 0.3 to 0.4 calories per sq cm per min. Because of the apparent daily motion of the sun, the burn is in the form of a line, the length of which serves to measure the duration of the sunshine. A continuously registering actinograph can also function as a heliograph.

REFERENCE

Sternzat, M. S. Meteorologicheskie pribory i nabliudeniia. Leningrad, 1968. Page 209.
(2) In astronomy, a telescope adapted for photographing the sun. It is used to obtain photographs of all or part of the solar disk in a wide range of wave lengths. A heliograph can be used in combination with a coelostat. Because of the tremendous illumination generated by the sun, the aperture ratio of the heliograph objective can be minimal. In order to obtain pictures of the sun with large linear dimensions, as large a focal length is chosen for the heliograph as possible. At the same time, so as not to increase the size of the instrument, additional magnification systems are used. The heliograph is equipped with a fast-action shutter (usually of the curtain type), giving exposure times of from 0.02 to 0.001 seconds. One of the first heliographs was installed by the Russian astrophysicist M. M. Gusev at Wilno (Vilnius) in 1854.
(3) In military affairs in the 19th and early 20th centuries, a light-signaling device for transmitting messages (by Morse code) with a mirror used to reflect light rays. The heliograph is effective over distances of 18 to 40 km in daytime and 3 to 8 km at night.

heliograph

[′hē·lē·ə‚graf]
(communications)
An instrument for sending telegraphic messages by reflecting the sun's rays from a mirror.
(engineering)
An instrument that records the duration of sunshine and gives a qualitative measure of its amount by action of sun's rays on blueprint paper.

heliograph

1. an instrument with mirrors and a shutter used for sending messages in Morse code by reflecting the sun's rays
2. a device used to photograph the sun
References in periodicals archive ?
Sales and service of all products will be handled by the sales and service hubs of the Wifag-Polytype Group and the Heliograph Group in their respective market/product application segments.
In 1888, a new heliograph was developed that was strong, portable, and used a square rather than round mirror offering more surface space.
Gernsheim rushed to London, where he discovered that the tarnished mirror indeed was Niepce's heliograph.
Their black and gray domes strain against the sky like balloons; their gilded crosses heliograph important messages to one another whenever the sun allows.
65) A method of communication introduced in the last century in the sunny climes of Africa and India by the British army was the heliograph, which used the reflection of the sun's rays to communicate over distances of even 100 miles.
telegraph Pneumatic transfer tubes Giovanni Caselli's facsimile pantelegraph The Edison wax cylinder The heliograph The teleharmonium Early twentieth-century electric searchlight
Heliographic Peak is named for the Army heliograph network used during the last year of the wars, when signals from mirrors were reflected across southern Arizona.
No telephones would be carried and our station would receive messages by flag from the signallers with the attacking force; which we would transmit to Brigade by heliograph or flag.
The Corps also pursued the use of other novel signaling methods to include the heliograph, which used mirrors to reflect sunlight, and the carrier pigeon.
So we went up and set up a heliograph, which reflects the rays of the sun, to establish communications with the whole of The Punjab.
Multicolored birds perch and chirp from the small antennas of an old heliograph, inactive for many years.