Actinograph

n. instrument used to chart actinic radiation

An actinograph is an instrument for measuring or estimating the amount of light available, in terms of its ability to expose photographic film. That is, it measures the actinic or chemical intensity of light, as opposed to radiometric or photometric amount of light.The earliest actinographs were 24-hour recording devices, using a rotating cylinder of photographic paper exposed through a wedged-shaped slit to record a graph of actinic light during the period of a day; hence the graph suffix in actinograph. Such devices were developed and described by Robert Hunt, secretrary of the Royal Cornwall Polytechnic Society in 1845, as an improvement on T. B. Jordan's 1839 Heliograph.
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(n.)
An instrument for measuring and recording the variations in the actinic or chemical force of rays of light.
  

n.
کرن ناپ

Eng: actinograph
Urdu: شُعاع نِگار ۔ شَمسی شُعاعوں کے کیمِیائی نَفُوذ کو ناپنے اور ثَبت کَرنے کا آلَہ ۔