Pronunciation: [hˈɛlɪˌɒɡɹaf] (IPA) 
The word "heliograph" is spelled as [ˈhɛliəˌɡræf], with three syllables and a silent "h" in the beginning. The IPA transcription shows that the first syllable is pronounced with a short "e" sound followed by a "l" sound. The second syllable has a stressed "i" sound and the third syllable ends with a "graph" sound. A heliograph is a device used for signaling in which sunlight is reflected from a mirror to produce flashes of light.
heliograph noun | hel·io·graph | \ ˈhē-lē-ə-ˌgraf \
Definition:
A heliograph is a signaling device or instrument that uses the reflection of sunlight to transmit messages between distant points. It consists of a small mirror mounted on a tripod or a similar stand, which can be tilted to reflect sunlight in a controlled manner. The heliograph was historically used as a communication tool when other means of long-distance communication were limited or unavailable.
The term "heliograph" is composed of two Greek words: "helios," meaning "sun," and "graph," meaning "to write" or "to draw." It captures the essence of how this device operates, by writing or drawing messages with sunlight. In order to transmit a message, the sender tilts the mirror to catch the sunlight and directs it towards the recipient. By adjusting the mirror’s angle, they can create a series of flashes and interruptions, which can be deciphered by a trained operator or by Morse code experts who interpret the system of long and short reflections.
Heliographs were widely employed in military applications, especially during the 19th and early 20th centuries, as a means of transmitting valuable information across long distances. They provided a faster and more reliable method of communication compared to couriers or smoke signals. The use of heliographs gradually declined with advancements in telecommunications technologies, but they remain historically significant as one of the early forms of long-distance optical communication.
An instr. devised for obtaining photographs of the sun.
Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874.
The word heliograph is derived from two Greek roots: helio, meaning sun, and graph, meaning to write or to record. Therefore, heliograph can be understood as the combination of these two roots to mean to write with the sun or to record using the sun.
