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 ?
In 1888, a new heliograph was developed that was strong, portable, and used a square rather than round mirror offering more surface space.
In England, the word was first presented in a lecture at the Royal Society, eventually winning out over its contemporary rivals photogene and heliograph.
These range from a machine to turn sea water into drinking water, a new lightweight heliograph signalling device and a shark repellent, tested and approved by the US navy.
From Kitchener's headquarters orders were flashed by telegraph and heliograph links across the veldt to a total of fifteen columns to intercept, contain and trap the rampaging Boers.
After Bauer's death in 1841, the heliograph passed from one person to another.
Their black and gray domes strain against the sky like balloons; their gilded crosses heliograph important messages to one another whenever the sun allows.
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.
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.
American stores issued them to preferred customers enabling them to buy goods on their credit-worthiness rather than any funds on deposit; # Final battle of the American Civil War on May 12 at Palmito Ranch, Brownsville, Texas; # 27 American states ratified the 13th amendment of the US Constitution abolishing slavery; # Henry Christopher Mance, of the British Army Signal Corps, built a heliograph, an optical sunlight based signalling device.
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.
Volkmar reported: Signal stations were soon established on both sides of the Monongahela River and communication constantly maintained between the separated forces by flag, heliograph, and lantern.
In this process, the heliograph, a glass or metal plate, is given a coat of lavender impregnated with bitumen of Judea to provide a stain.